Bone Health for Ultrarunners with Craig Sale | KoopCast Episode 28

what's going on trail and ultra runners welcome to another episode of the KoopCast as always i'm your host Jason Koop and if you saw the title to this podcast bone health i guarantee you it perked up your ears because maybe you've had a stress fracture in the past maybe one of your training partners has had a stress fracture in the past and you realize what a huge issue this can be in ultra marathon running but you know what your bones play a bigger role in your health as an athlete and in your health as a person and it's not just something to avoid stress fractures and injury injuries to bone are not just something to avoid and so to get to the heart of the matter i brought in a bone expert and professor craig sale out of nottingham trent university craig is a professor of human physiology and the director for sport health and performance enhancement research center at nottingham trent university he is also a fellow of the american college of sports medicine he comes to us with a tremendous amount of experience in bone health for athletes he's written a number of different papers on the subject a lot of which i am going to link to in the show notes and we just had a just an absolutely fascinating conversation about all things related to bone the roles they play for athletes and in runners and what is bone health

you know a lot of times as athletes we can mark our physical capabilities or our physical fitness with a time trial or a set of intervals or a race but we don't have a really good way of determining what good bone health is we also talk about how diet can affect can affect bone health and we also talk about how loading or training can affect bone health as well and finally we get into some practical implementation for athletes and for endurance athletes out there so i hope you all find this podcast incredibly informative and without any further ado here we go here's my conversation with craig sale about all things related to bone health i appreciate uh you joining in advance uh i take it that microphone that i sent you didn't make it on time it's stuck somewhere in the nether nether regions of shipping i mean i think part of the issue is obviously with the lockdown and stuff um you know everything's a little bit disrupted and so you know something that would normally get there in in a in a day or two is taking a week and that kind of thing you know so it's funny because i've got a few of those i have a few of those microphones kind of floating around the uk and uh uh europe in fact yesterday i was uh i did a recording with uh glenn

davison uh you might be familiar with yeah yeah oh no okay yeah and uh getting usually getting them around from place to place it's only you know maybe a two or a five day ordeal right now yeah or you usually it's only a two or five day ordeal but now it's you know who knows i think everything's sort of much much slower at the moment i think you know even though there are essential businesses around and the couriers are still running back and forth and you know amazon and making billions um i think it's just i think it just depends on how you catch it whether they've got a light shift or whatever and it can just just throw things off a little bit but yeah my uh my amazon delivery person and ups delivery person who i i know very well because i get a lot of deliveries obviously for not only for the audio equipment but also for like athletic equipment running stuff or my coaching business and whatnot we used to hang out when they'd come by and drop stuff off and now because of you know probably a combination of fear and they're just too busy it's like they just drop stuff off at my porch and bolts yeah we're kind of similar i had a bit i had about a 20 minute conversation with the with the amazon uh delivery person the other day and you know they they were saying it's just very busy crazy right i i imagine that you're it you're people with um people with a specialty in bone health

they're they're kind of hot commodities in the endurance spectrum and that's just simply because of it's really because of two reasons is one is like there's a high rate of uh prevalence of bony stress injuries in the endurance community but also those types of injuries are killers i mean they tend to be season enders and they also tend to be very uh very repetitive and as a byproduct of that athletes get really hyper focused on bone specifically from this viewpoint of i'm trying to prevent a stress fracture yeah but in reality the bone plays a much bigger part in an athlete's health as a whole so before we like dive down the injury and the stress fracture rabbit hole too much let's like broaden the view up let's broaden the viewpoint up a little bit and just talk about what roles bone plays in an athlete's life in general yeah no that sounds good to me yeah we can we can definitely go down down all of those routes um i think you're absolutely right you know i think um you know quite often people do focus a little bit too much on the on the stress fracture injury thing now that's obvious you know but but i think you know from from my perspective i normally say there are two concerns really for the athlete and one is that longer term bone health perspective and the other one is the the bone stress injury you know and and what do we know about how how prevalent those bone injuries are and how

prevalent these like musculoskeletal injuries are in athletes these types of studies are always hard to do and typically they're done in like college uh types of uh settings where they're looking at a collegiate team or a group of collegiate athletes or a specific group of collegiate athletes like females or cross country runners or but can we like like style like stylize a little bit of the incidence rate a little bit amongst endurance athletes well i think you've summarized that really really well there actually it's very very difficult to get a um specific injury status of endurance athletes as a whole i mean i think generally speaking you know there's there's such a wide uh reported incidence rate from you know a couple of percent in in some groups right the way through to sort of 70 75 80 percent even of of people in in other um in studies and in other reported groups and generally speaking in people that have come through my lab and so these are not studies that are designed specifically to look at this but in in groups that have come through uh our lab here at nottingham trent university we've tended to see you know relatively small percentages of individuals um who perform um you know games play so rugby players for example tend to have quite a low incidence of bony stress injuries you know around the one two three percent mark um but right the way through to a group of triathletes that have come through the lab the incidence rate was up at 75 percent you know ballet dancers up 80 percent so i mean it there

really is a very very wide range and even within specific athlete groups i think it it often depends on when you when you capture the information how you capture the information a lot of people for example um don't necessarily record stress fractures or only those stress fractures that have been radiographically um confirmed you know through through imagery through through mri or whatever and they look to do athlete report which probably makes it exactly i mean you mentioned your lab and you you have a lot of tools available to to to diagnose these things and also to uh also uh using blood markers to look at some of the indices of bone health but we i i hear this term get thrown out a lot in the lay literature and also through the popular media we need to be concerned with our bone health but i'm not convinced that we have a really good working definition of that like athletes will kind of like look at their fitness and say okay i ran these intervals faster yesterday than i did the week before that and so i'm obviously more fit i'm more capable of producing a you know high quality result but when we're talking about when we're talking about this this word in quotes bone health is there a way that we can actually ascertain does a person have good better best poor type of bone health so that's a really good question and i think you're absolutely right is that i think you know what what

bone health tends to mean to people is probably uh different and it quite often you know depending on who is you're speaking to and what their focus is so you've already mentioned for example that um you know that the bony injury so somebody who's receiving or or getting a number of bone related injuries probably has poor bone health as far as that focus is concerned but that doesn't necessarily mean to say that that same individual also has low bone mass for example so i mean i think when you speak to a lot of people what they are talking about when you say bone health is is the the absence or the presence of known bone diseases which is osteopenia and osteoporosis so this is a disease that's characterized by largely low bone mass but also a micro architectural deterioration of the bone tissue and what that does is that leaves the individual susceptible to to fractures so osteoporotic fractures and then that can be quite serious but generally speaking you don't often see too many individuals that are you know younger individuals with osteopenia and osteoporosis you certainly can but it's it's far more prevalent and common in in the older population of course um because that's not necessarily health that's the absence of disease which is not quite the same thing so in terms of bone health i would say you know um you know it's having a sufficient bone structure and strength to cope with the demands

whatever they may be that you're you're putting upon the skeleton that's how i would sort of denote bone health um and of course that you know a lot of these things also depend on the number of different ways that you look to measure it as you as you mentioned so you can look at you know the one of the only ways to really look at an acute effect on bone health at the moment is through biochemical markers in the blood but interpretation of those responses is is fraught with difficulty um and one of the other you know i suppose the the most common way that the people look at bone health is by by looking at bone mass or bone mineral density via a dexa scan which i'm assuming many of your readers will be relatively familiar with and this this provides a an estimation of the amount of bone tissue bone mineral tissue that that you've got um but of course you know even that only predicts about 60 to 65 percent of bone strength so you also need to consider other elements of the bone including you know the the geometry of the bone its micro architectural structure so this is this is that the difference between this soft spongy bone and this one that's soft it's the this open spongy bone and this compact hard bone um and so you know there are a number of different parameters that would make up any measurement of bone and therefore what makes bone health so that's a rambling answer to the question no it's it's

complicated and i think that um there's a few things that have kind of done a disservice to determining bone health uh for athletes and one of them is kind of this commercial availability of using blood bowel markers to determine all different types of health of what one of which is bone so you go in you get a blood draw commercially the commercial lab and then you have some third party interpretation of all of those blood biomarkers and they try to they try to kind of compartmentalize them into your cardiovascular health your stress using cortisol and things like that and one of them is actually is actually bone health but as you really eloquently uh just displayed right there it has it has to do with several different things and even when you have all of those things available which you do in your lab it's still hard to tell a single person when you've done the dex scan when you've done the uh when you've done the biomarkers when you've looked at everything it's still hard to tell that one person yeah your bone health is excellent poor good you're not at risk of a stress fracture you are at more risk of a stress fracture it's just complicated yeah really complicated and i think you know using biochemical markers in particular and trying to extrapolate out an interpretation into overall bone health is fraught with problems i mean it is very very difficult and sometimes depending upon the situation it's it's quite hard to to necessarily say that having a high bone formation and a low bone

resorption is good and the opposite is bad because at any given time within a bone remodeling cycle those things might be quite important independently and of course the big problem you've got with that is you're you're you're taking these measurements from the circulation but of course you don't know where these markers are actually coming from so when people start talking about bone turnover markers it's it's a little bit um confusing because you're not really looking at direct bone turnover right i.e bone turnover at the level of the bone cell is a coupled process but obviously what you're measuring in the circulation is not necessarily directly reflective of that so in other words the the the bone formation marker responses that you're seeing could come from a completely different bone to the bone resorption marker responses that you're seeing so so that that's problematic of course and as far as athletes are concerned another interesting one even with dexa which most people would see as being you know the providing the providing the definitive answer on this is that you know quite often you compare these to normal scores so to t scores or z scores relative to age etc but of course there what you're really doing is that is comparing that individual's responses to a to a standard normal individual across a standard curve and of course athletes quite often don't exist um slap bang in the average person

category they're you know they're normally what you know one end or the other so you know you take a a marathon runner for example it might be you know 55 kilos and compare that to a rugby prop forward it might be 120 kilos you know there's there's the two extremes right there so yes you know is it is it relevant to compare or to analyze someone's bone house if they're an athlete or one of those athletes in particular relative to long values it might not be yeah and so what's starting to emerge is a little bit of this dichotomy right in order to it's very very difficult and complicated to tell somebody if they have good or poor bone health but the the practical solutions and i always try to drill these conversations back to the practical because we tend to get kind of we tend to get over focused on some of the nuance the practical ramifications for the athlete that the athlete can actually do to better ensure their bone health in a lot of ways is actually relatively quite simple and revolves around energy availability being one of if not the biggest driving force and ensuring athletes have adequate bone health why why don't we start to start to talk about how energy availability specifically affects bone health and then how critical it is to have those higher levels of just total caloric energy availability

yeah again i mean that's common if we can just go back a step i guess there are a couple of main you know modifiable factors i suppose that could influence bone health in the athlete and one of the important ones quite often which is is not often a a popular message for the athlete is to moderate training load of course so so of course one of the big problems may be you know the the training load or a novel present it well this is as far as bone injuries are concerned specifically but a novel presentation of a new training load or an increase in volume or a change in equipment a change in surface those kind of things can exacerbate the the bone injury risk um but of course you know same for military personnel and athletes that they don't often necessarily want to change their training regimen too much and so you look to other things and and diet and nutrition undoubtedly as well as sleep recovery and other factors like this uh will influence the boat um albeit maybe not as much as the mechanical load which is probably one of the largest effectors modifiable effectors of of of but i think you know if we then drill that down into to diet and nutrition and then certainly energy availability is a is a critical component for sure and there's this there's this number that's been floated around in a in a paper that uh you wrote to ensure adequate bone health and that's 45 kcals

per kilogram so why don't we dive in a little bit to to that recommendation that you propose like how it came about and then what are some of the nuances of the other levels of the caloric recommendations that are are listed in the paper and all of these these papers that we reference will be in the in the show notes for people to access afterwards yeah i i think i think it's an interesting one so i mean of course you know energy availability i mean we probably need to go back to maybe basics but it's it's calculated as the dietary energy intake minus the exercising energy expenditure and it's usually reported in kilocalories per kilogram of fat-free mass or lean body mass and nuance there but they're relatively similar terms and relatively similar amounts um so it's essentially what you're looking at is it's the amount of increased energy room um sorry the amount of ingested energy that's remaining available to support that basic bodily function um after the energy required for exercise has been taken into account if that makes sense so you know yeah you you are you are right then and one of the things that's been postulated is that energy balance seems to occur around 45 kilocalories per kilogram uh lean body muscle fat free mass per day and you're also absolutely right that you would struggle to see

any decent level or elite endurance athlete get anywhere near that um so there are reports that um you know amenorrheic female athlete endurance athletes are down around 15 kcal per kilogram lean body mass per day which is a fair way off the 45 energy balance uh consideration and so one of the things that people have started to to to sort of try to figure out i suppose is is there given that you're not going to get that endurance athlete 245 kcal per kilogram lean body mass per day is there a a threshold for want of a better word above which you will not necessarily see such detrimental effects on the bone and really we've only got one or two studies that point towards this kind of threshold and so you know i i definitely would not suggest that this is definitive in any way shape or form um but there is some suggestion that getting an athlete above 30 kcal per kilogram lean body mass per day would limit the potential negative effects of low energy availability on the bone but again that's that's based on a single study with an independent group's designs that means different athletes were in the different in different low energy availability groups um and so you know that's whilst that's a was a nice study that's still pretty thin evidence on

which to base a clear recommendation so i mean i think all we can really go on right now is is to try to keep the periods of low energy availability as short as possible and you know that's easier in some types of athletes than others very very difficult in a in a in an elite endurance population for sure um and and and the other one might be to try to periodize low energy availability periods in the training schedule such that you can have periods of low energy availability that can still support a lot of those training and competition goals that the athletes are focused upon but at the same time there are also periods of much higher energy availability to try and limit the negative impact on on the bone does that make some sense yeah absolutely and the this this concept that low energy availability isn't necessarily limited to a 24 hour period which a lot of athletes will look at a lot of athletes will look at okay here's the amount of energy expenditure i have in a day as you mentioned and here's how many calories i took in in that day really it needs to be broken down into smaller and smaller increments and that's where it starts to get really fuzzy but also extremely complicated for an ultra marathon athlete which is going to be primarily this audience because some of their training sessions last four six eight ten hours and so this entire period of low energy availability can stretch into the 12 or even 20 hours

even if they're trying to refeed uh the entire time so i'm i've always i've always kind of wondered when ultra marathon athletes are undertaking these extremely long arduous training sessions of which they might you know they they might require three or four or even more than that thousand calories to actually kind of complete the activity and there's no way that they can match that during the activity itself or even in the several hours afterwards because you can only tolerate so much food how like how much of a risk is that to bone health when we undertake those types of activities again it's a really great and and and quite complicated questions right um so i mean i think you're absolutely right one of the i don't have any experience in in in doing um any work on ultra marathon although i think that would be a great population of athletes to look at but but we have done a few studies on on triathletes on on some good level and elite level triathletes and certainly you know you're you're talking about athletes there that train two three or four times a day pretty much every day there isn't really a complete off day and you know we've done a doubly labeled water study in in some of those athletes and and they are sort of utilizing four five six seven thousand calories per day on average over

a 10 day period this is so you know that's a massive amount of of of energy expenditure um and it's going to be really difficult to to track that and certainly on a day where you're training four times in a day trying to eat enough food to ingest uh you know the required amount of energy is going to be you know very difficult if not you know virtually impossible so it practically it's very very challenging to to do that and i think in terms of negative effects on bone health again it's one of those things where i think what we're clear on is that consistent and prolonged low energy availability over time is definitely detrimental to bone so so those individuals who are in a consistent low energy availability state over weeks months years then then that is is definitely um not a good thing as far as the bone is concerned but in terms of for example those individuals that might um do that intermittently so if we think for example of a weight classified athlete who may go for periods of low energy availability for a few days or a week or so at a time and then refeed quite vigorously after that period of low energy availability it's not quite so clear cut as to whether that is you know negative or not but certainly you know certainly individual periods of low energy availability even if

they're quite severe sort of 24 48 72 hours is not generally a problem you might get some short-term perturbations of bone metabolism but you you know as far as the overall bone health over time is concerned it's not not a major problem problem is what happens if you continue to repeat that um again that that intermittent application of low energy availability is not quite as clear but my guess and it it is just a guess really is that that would not be as detrimental as something that was sort of continuous and prolonged yeah you talked a little bit about uh periodizing low energy availability which i think is a fascinating concept and i honestly think a lot of endurance athletes who are trying to use low energy availability to lose a little weight are actually doing that in the they're doing it in the opposite way of which they need to be doing it they're taking a big session four five six hours as we were just talking about and because there's such a high caloric expenditure on that particular session they're using that because of the heightened requirement for calories they're using that as the period of which they're inducing this low energy availability so therefore that they can lose weight with my athletes i almost i take the opposite approach with athletes that that are looking to lose a few pounds where i look at where the

training is the least intense we're doing the least amount of intervals the least amount of you know high volume super critical workouts and things like that and we try to shave off pounds during those particular time frames so that they have the adequate nutrition not only support bone health but also support all the other adaptations that we're trying to make during during those training sessions i'm wondering if you had any thoughts on how an athlete might actually go about like periodizing some of their nutrition specifically for low energy availability or weight loss in a in a healthy way like what would be the best way to do it yeah i mean i i think my my again my my guess is that the way you're proposing to do it makes the most sense to me and i think the only resource that i've seen and and this is what based my this is what i based my my recommendation on in that paper that we were talking about um was this study and it was a study by uh trent stellingworth i don't know if you know trent but um you're very very good um exercise physiologist and and you know dabbles in performance nutrition for sure as well but but he conducted a paper on a on a canadian elite athlete where they periodized some of these low energy available periodized some of this low energy availability and low carbohydrate availability and um um it seemed to be relatively successful in maintaining a number of health related parameters not only sort of bone but menstrual function and and other things as well so um i can certainly dig out

that paper and sent it to you it's probably the the best piece of evidence that i can i can point to towards how and why and and where you might look to periodize but but certainly this is not something that has been specifically looked at as far as bone is concerned as far as low energy availability and and bone is concerned at least not to my knowledge um and so i think that's that's work to be done and work in progress quite frankly yeah and this is just something once you mentioned it hasn't been done a lot and i'm familiar with that case study we'll link it in the uh we'll link it in the in the show notes certainly but i've always looked at it as low energy availability is always a risky proposition across a number of different parameters the one the one that we're talking about right now just happens to be bone health if i'm ever inducing that intentionally with an athlete i want to minimize the negative outcomes as much as possible then i look at what are the what are the training interventions that i'm using that have the least negative outcomes associated with them and it's typically lower volume training easier running maybe there's a period of three or four days where we're just doing you know one or two hour endurance runs or something like that i look at those as the opportunities because the risk isn't as high versus hey i'm going to go out and do an eight hour run and i know that you know i'm going to be in a two or three thousand calorie deficit after that run anyway so i'm going to use that to lose a little bit of weight i don't look at those as the opportunities because of all the other risk factors associated

with it yeah i i think that that makes that makes absolute sense to me and i think you know i i definitely understand some of the rationale behind looking towards low energy availability availability periods same with low carbohydrate availability periods in that some of these practices may well be seen to to drive some of the adaptations that you might want towards an endurance phenotype so i mean i think that there are definitely you know positive modifications as far as you know training performance goes that you might want to use these kind of strategies low energy low carbohydrate availability strategies for but um as you rightly point out there's there's a trade-off there and i think you know if you if you go too far with those then then there can be other detriments to to performance to health to immune function to all sorts of different things and and one of those things is is definitely going to be bone health if it's continued over a prolonged period of time well you gave me a perfect transition to the next topic there um we we can't let you off the hook here without start talk without to without talking about low carbohydrate and ketogenic diets because it as you're aware of it's it's a quote unquote thing and particularly in endurance circles and then more specifically in the ultra marathon circles it's even it's even a bigger thing and you know you might be able to characterize it as

contentious like people dig their heels in oh i'm in the high carb camp i'm in a low carb camp but there is this spectrum of strategies with which endurance athletes can use as you said to drive this endurance phenotype they can train with low carbohydrate availability through a number of different ways fasted way two-a-day training and things like that or they can adopt a low carb diet either a ketogenic diet with less than 50 grams of carbohydrates per day or a low carb diet where they're restricting their carbohydrates to 20 of their total macros or something like that a lot of those flavors are becoming popular in the ultra marathon scene certainly because they look at this proposition of i want to be able to drive as much fat burning as possible in order to fuel in order to fuel myself for this performance it it does as you mentioned come as a consequence regardless of whatever those strategy what whichever one of those strategies you want to undertake and i don't want to like peel apart each one because that would take five podcasts or so let's uh which we could do i'm i'd be up for that but let's let's let's just try to generalize what like how carbohydrate availability specifically can impact bone health and in certain cases when it might impact it more so than others yeah again it's another one of those sort of areas that that hasn't had too much specific research done on it um and i think you know

a coin of phrase from from some presentations i've seen by by james morton a friend of mine here from from liverpool in the uk and and he says it's not necessarily about high carbohydrate low carbohydrate it's about smart carbohydrate and what he tends to mean by that is that each one of those strategies has a potential place to either drive a training adaptation to drive an individual performance to drive a part of an individual performance quite possibly um and and that that seems to make some sense to me but of course you know people do uh i think it's definitely a contentious uh area of of consideration but i mean i think there are some sensible reasons why individuals would want to go low carbohydrate um at various points and and that makes that makes actual actually physiological sense to me um as well but i think again you know rigorously following any of those patterns without the understanding or following the nuances is is potentially problematic um for the bone as well as as many other things but but if we focus on the bone specifically there are a few studies that that suggest that the carbohydrate can influence um the the bone metabolism so there were some some original studies out of university of sheffield here in the uk um which um suggested that the carbohydrate could be important and feeding could be important in moderating

um bone metabolism but but we've also those weren't necessarily and what they weren't at all exercise studies and that's the other thing so i think when we've done some acute studies so cut we've done some studies with carbohydrate feeding um during exercise we've done a study with carbohydrate plus protein feeding post exercise there's been a recent study which was conducted by james morton um showing that low carbohydrate availability independently of low energy availability might influence short-term responses of the bone and of course there's a study or two now just coming out of the lab of louise burke where they've looked at the short-term ketogenic diets and and changes in bone metabolism and generally the exercise studies would suggest somewhat negative connotations from low carbohydrate availability as far as the bone is concerned the study of the bone is concerned but again a word of caution there i suppose in some respects is that most of those studies haven't been scaled up and conducted over more prolonged periods of time or what happens when um again you use or what happens if you switch from a low carbohydrate diet to a higher carbohydrate diet in a different phase of training or competition as some athletes may well do

um and so again it's it's one of those highly nuanced questions that we don't have an awful lot of um a lot of understanding of and it's probably something that will develop over the next few years we're just starting uh i'm just starting as as part of a team that's at university of limerick in in ireland we're just starting another a PhD program of work now on exactly this topic so hopefully we'll generate a bit more data over the coming few years on this but um yeah it's certainly an interesting one and i think you know you can counteract some of those claims as well by looking at the fact that generally for example diabetics tend to have poorer bone health than um the non-diabetics uh you can also characterize some of the studies in particularly younger populations who have been receiving low carbohydrate diets for for a number of different reasons they tend to show um either no detrimental or sometimes even positive effects of a low carbohydrate diet on the bone um so again highly problematic to try and give a definitive answer on this right now is it just isn't enough information but all we can say is that the majority of the acute studies um that have fed carbohydrate so not necessarily low carbohydrates that fed carbohydrate have shown positive effects on the bone and obviously those one or two studies out of louise's lab have shown potentially detrimental effects of ketogenic albeit short-term ketogenic type

diets on on bone health yeah the one uh the the one out of the burke lab is the one that i'm the most familiar with i found i found quite fascinating because they were able to control for all of the other variables all the other nutritional variables that you could try to control for including all of the micronutrients calcium vitamin d and things like that the thing that they that they that they can't control for because they're athletes is the training load so they still had an intensified training load when they switched some of the athletes over to a ketogenic diet and a lot of people will look at that and i do myself can look at that and go well it's the mismatch between the type of energy input and the type of energy output that the athlete is actually undertaking is what is a big part of any of the negative consequences that are going on in particular in in which would also include the bone health piece yeah exactly i mean you know any of these there's no such thing as a perfect study of course and right that was um you know to be honest that was a that was a heck of a study they did they did a very very good job at controlling as many different variables as they possibly could particularly over that time frame in elite elite athletes i mean that's that they need to be congratulated for that but yeah of course there's always going to be those you know there's that other question about is three and a half weeks on a ketogenic diet long enough etc etc but you know you try doing that study over a much

long longer period of time it takes an awful lot of effort to get the level of control that they exerted on that that experiment so try and do that over a much longer period of time for example would be very very difficult but yeah but i think that's probably the one of the best pieces of evidence we've got currently um yeah we need we need more and and you know we need probably more prolonged periods of carbohydrate um intake and um and and you know many other different factors to be considered but but one of the other interesting points you make if we go back to the low energy availability debate actually that that you just triggered in my mind there is that even then it's quite difficult because if you look at particularly from a dietary intake perspective if you look at the way in which a lot of individual studies have reduced the energy intake they've done it by taking an habitual diet and pretty much cutting it in half and of course what you get then is yes you get let's say a 50 reduction in energy intake but you also get reduced intake of things like calcium vitamin d protein carbohydrate so with a lot of those studies you can also question really whether it's energy of you know low low energy that's the issue or whether it's nutrient availability that's the issue and and so that's that's another avenue of nuance that that needs to be investigated is you know is it solely low low energy or is it low nutrient so let's pivot to that a little bit um and we're only

going to beat the nutrition horse so much here because i do want to train i do want to i do want to transition to the load part of the equation which you which you referenced earlier in terms of bone health but you're absolutely right it's not just energy availability that's the big one i think that's the big you know that's the big object in the room that we all need to pay attention to but there are also some critical nutrients that are also incredibly important for bone health why don't we just give a quick overview of what those what those nutrients are yeah so i mean there's there's a there's a whole long long list of nutrients that they generally support bone health and if you go to that nutrition and bone health paper that you're you're going to pop up there's a i think it's i think it's the first thing i think it's table one in that in that publication that lists a number of different nutrients that are important for the bone i mean obviously the ones that people will be most familiar with are going to be probably calcium vitamin d maybe phosphorus um but there are you know magnesium is important zinc copper potassium of course um vitamin k2 vitamin c vitamin a there there are a number of different micronutrients there that are relatively important for for bone health of course you know like i say that the big ones really that everyone would recognize probably are vitamin d and calcium and they they are vitally important for for the bone for sure um but you know there are a whole range of both direct

and indirect effects of different nutrients on on the bone and supporting bone uh metabolism and and so you know i think the things that would nutritionally support the skeleton of everybody is going to be you know the same if you're an athlete you know so you know getting that nutritional support for the the bone is going to be vitally important of course one of the things we again we're not particularly clear on is how you know the types of exercise and training that athletes perform how that influences the nutrient requirements the micronutrient requirements in particular of the athlete so you know what is what is um or what meets a recommended daily allowance for a a non-athlete might not necessarily be sufficient for an athlete um and of course one of the other things to think about is if you're just looking at recommended dietary intakes what you know whatever you know version of that you look to follow they're really designed to prevent a deficiency in a majority of the population what they're not there to do is optimize a situation and so we still don't really know what the optimal situation for an athlete would be as far as you know those the availability of those those micronutrients in particular um when we when we talk about micronutrients and vitamins a lot of

people are first going to turn their attention towards supplementation and one of the things is one of the things practitioners coaches and people like yourself always stress with athletes is a food first approach to fuel themselves with the calcium the vitamin d the iron and all those other things but as an athlete specifically in respects to bone health is there anything that they should be or would consider supplementing on top of a normal healthy diet that's going to cover their caloric requirements for the day well again it's one of those interesting things i mean we've covered a little bit about the practicalities of feeding an athlete who might be training for either a very long period of time in a given day or might be training multiple times in a day and obviously you know you know feeding whole food at any given time in that period might be quite tricky and so turning the supplementation whether that be via carbohydrates or protein or whether it be you know some calcium supplementation for example uh it is always a strategy worth considering once you've you've determined what you can and can't do via food alone i would definitely reiterate food first is the way forwards absolutely 100 percent um but then where other things um intervene so so for example if you're trying to correct

a deficiency and quite often in athletes the the two things we talk about there most often probably are vitamin d and iron so if you're trying to counteract a deficiency um then supplementation is worth considering um that there may be some acute effects and positive effects of supplementation around hard exercise training sessions for example so there's a little bit of a little bit of evidence around pre-exercise calcium supplementation to support um bone health particularly in sort of more prolonged endurance type activities um and of course we've shown that feeding some carbohydrate during the activity or feeding carbohydrate and protein after the activity can modify the the bone metabolic response but again these are quite acute studies and we we need to see really what happens to adaptations if you scale that up over time and that's by no means clear cut so i mean i think i think depends on on you know again what you mean by by supplements but i think those kind of you know those kind of consistent supplements with you know multivitamins and things like that are are worth considering where there's a dietary deficiency for example or insufficiency um because an athlete may not be able to eat the the food that you're talking about or or they may not necessarily like the the food that they need to consume to get a lot of these

uh micronutrients in so so where you're talking about correcting a deficiency in the diet or uh um some some other form of deficiency then supplementation is is always a consideration is there is there is there anything that athletes need to watch out for for supplementation because there's a lot of products on the market that and i think this is this is particularly relevant with bone health there's a lot of supplement products out on the market that will claim that they improve bone health when in fact if taken in excess or even sometimes taken to the dosage that is recommended on the label it can be detrimental to bone health and in an effort of full disclosure you're allowed to you're allowed to you're allowed to throw anybody under the bus on this podcast i always mentioned to my guests that there are no sponsors on this podcast there's intentionally no sponsorship on this podcast i don't look for it i turn them all down when i bring them in and one of the reasons is because i get solicited particularly from nutrition companies a lot to provide advertisement on uh on this podcast and i don't want that conflict of interest to ever to ever exist and i know that you're familiar with this area i know you're familiar with this area so is there anything that athletes specifically should watch out for in terms of supplementation things that might actually impair or be detrimental to their bone health well i mean i think again you know the the great rule of thumb with this is you

know you always beware of anybody bearing gifts right because because if it if it sounds too good to be true it usually is too good to be true um and so you know no i mean i i think generally speaking it there isn't any need to go for mega doses of of anything or to look at really extrapolating out um you know because there's always this danger that that you say you know you know so and so a is particularly good for bone health and and or whatever it may be or performance is even a bigger one and then the natural assumption of people looking at that is that more is always better and that most definitely isn't the case um and to a certain extent we've gone through a little bit of that with things like vitamin d for example where you you've now got people throwing in really really large high uh amounts of vitamin d to the system and and i think there is a little bit of evidence actually that these sort of mega doses that are designed to prop up the vitamin the circulating vitamin d concentration over over a prolonged period of time might actually be a little more detrimental to to the bone there are a couple of studies not in athletes at all but in older individuals where um the incidence of falls and fractures has gone up with really really high dose vitamin d supplementation again those studies are associational they're not necessarily causative but

um you know you can you can see you you you can see some potential there with these sort of mega dosing um and i don't necessarily think for the athlete that there is any need to do that um you can stay within relatively normal parameters you know maybe a little bit more than the recommended daily amount but like i said we don't really know what the what the position to optimize the bone health and the micronutrient availability of an athlete is yet so it's even difficult to say that but one of the big things that that i think you need to be careful about is is where you get your supplements from actually and what source and are they appropriately tested particularly if your athlete is um open to to drug testing as part of their their training and competition because um you would want to make sure that you're getting a you know a supplement from a reputable source that tests its products and gets them independently tested on a on a batch by batch basis because otherwise you could find yourself of course and you know inadvertently failing a drugs test and there's there's plenty of examples of that kicking around oh yeah you ain't kidding so usada is right around the quarter from me and we have a lot of mutual colleagues over there they that that's a battle that they fight daily yeah the contaminated supplement battle it is a it is a big big problem and i know it's worldwide but particularly because supplements are not regulated uh at all here in the us it is a it is a huge issue but i will i i i got a kick out of one of your comments um that we tend to think that if a little

bit is good mega doses are better yeah if there's any if there's any cohort that is subject to that fallacy it's the ultra marathon cohort if a little bit of mileage is good a whole lot of mileage is better and then mega mileage is our best and we tend to take that and translate it into other areas of our lives in vitamin and supplement might actually might actually be one of them um yeah quantity and quality are not necessarily the same thing exactly all right i appreciate that craig uh so let's let's pivot a little bit and talk about women and i know you're home because you're in quarantine right now so if you so if you need to if you need to bring your wife into the equation who you can mention to start to discuss some of this you're more you're more you're more than welcome to and we can explain while we're laughing about that a lot of listeners aren't going to be familiar with the connection there but there are certain things that women need to pay attention to uh in regards to bone health that are obviously different than men uh not only on the susceptibility side but also things having to do with their menstrual cycle and where they are in their mental menstrual cycle and any sort of uh contraceptives that they actually uh might be taking can you give us kind of a broad overview of some of the like the of the nuances that women might have to look at in terms of how to maintain proper bone health yeah you're definitely talking to the wrong sale as far as this conversation is concerned but um you know i mean i think certainly you know that there are some little bits of evidence

for example if we go back to one of our previous conversations that the women might be a little bit more susceptible to the effects of of um low energy availability on bone health for men such that maybe they they have a their bone has a bigger response at a at not such a severe low energy availability as you would need to induce in the men to see the same negative effect on the bone but again that's really only one or two studies and and that's not definitive by any stretch of the imagination but of course one of the things that that that is probably easiest to point to as far as this is concerned is the is the female athlete triad that most people will be you know familiar with that term i'm sure and this kind of links in um along a continuum between so it links in this this triad so essentially the the triad is is bone health is menstrual function and energy availability and and each one of those exists along a a continuum between sort of what is is normal you know so you've got you know energy replete normal menstrual function good bone health right the way through to a clinical manifestation which is you know problems with you know abnormal menstrual function um low energy availability and poor bone health stroke osteopenia osteoporosis and so you know this was a this was a a syndrome that was was initially described as the name would suggest specifically

in female athletes um although it has now moved on to consider whether there would be a male athlete triad and and of course there isn't that other syndrome the the red syndrome um that that kind of describes a very very similar thing will be on a on a wider set of symptoms um so yeah there are a number of things and of course um the the age associated reduction in in bone mass tends to be a little bit greater and a little bit quicker in women particularly post-menopause once those protective effects of the estrogen concentration um drops out so you know kind of around that age of 50 55 the there's a slightly accelerated bone loss in in females than than there is in males um of course that might not necessarily be particularly a problem for the age of many elite female athletes but but of course if they've got the age of many of these spots things that impinge upon the attainment of peak bone mass during childhood and adolescence and early adulthood for example then and and therefore their peak bone mass is lower then they've obviously got a potentially a bigger problem once the accelerated rate of age associated bone loss comes in so um i think there are a number of things there um you also mentioned sort of the use of hormonal contraception and and there are little bits and pieces of evidence around that

that certain types of approaches may negatively affect bone health um in particular we've got a little bit of of data that's suggesting that those individuals who um use the contraceptive injection so they down regulate their their estrogen concentrations over more prolonged periods of time so maybe two three months at a time that that is a little bit more detrimental to the bone than um than other contraceptive approaches but again it's small numbers it's only really one or two studies so that's by no means clear cut either but um yeah i'd say they're the main issues we'll have to so so for those of you who kind of were missing the inside joke here uh craig's wife christy has happens to have some domain expertise in female physiology and i've heard her on a number of podcasts and i've read a number of her articles so we'll have to we'll have to bring her on there very specifically maybe both of you in tandem to talk specifically about that do you guys talk about the at the dinner table or can you just like put all this stuff aside when you sit down and you have to have a normal yeah no we try and we try not to talk too much about that um the kids normally start rolling their eyes if we do that but um we normally sort of we are we we do we are we hold some some decent debates at times but um yeah we try and keep it to a minimum if we can

that's gotta be eating to be honest where the dinner table there i was about to say because it you know it always involves food and there's something around the dinner table and i just can't imagine it's just incredibly complicated and can get way out of control way too quickly yeah particularly as we quite often come from you know these sorts of things from very different perspectives so it can descend into an academic argument fairly quickly but uh yeah it's all it's all good okay all right well we'll we'll we'll broach that at some point we work together a lot so we're all right oh man okay let's go let's go on to the last topic so we we talked a whole lot during this podcast about how nutrition modulates bone health but as you were very quick to mention once i dove down that rabbit hole the other side of the equation is loading and this is actually something i think that more athletes uh put uh they just put a bigger magnifying glass on because they want they're looking at training load in terms of the performance outcome how much mileage can i pack on how quickly can i add intervals how quickly can i add speed work and things like that but we also know that training load in them and the rate at which you uh start to increase training load can negatively affect bone health and so much so there have been all these retrospective studies that have looked at athletes that have gotten injured and said okay what are some of the key indicators to uh that we can tease out of this process of an

athlete getting injured is it the amount of mileage that they did is it the rate that they ramped it up what can you tell us about how athletes can safely manage their training load to avoid this situation of having some sort of bone stress reaction or or bone fracture yeah it's it's again it's another really good question and um i think you know one of the things that you you you sort of pointed towards there in terms of of what you're talking about is is that kind of idea of whether it's the duration of load or the magnitude of load that really makes a difference um and and you know again that's that's a really really good consideration because um it's not immediately it's not immediately clear either in terms of whether it's you know that high intensity but relatively low duration that's the problem or whether it's the other way around whether it's that low consistent low produced over a prolonged period of time that's the problem um and and it and it could just as easily be either actually um yeah and and that i suppose is the problem i think in terms of a few clear um in terms of a few clear guidelines thinking about it um i think you tend to see more bone

stress injuries when you acutely significantly increase the load so if you if you for example increase mileage quite significantly so if we take or you you increase the intensity quite significantly or you change footwear or you change surface particularly if you do again you combine two or three of these things i think the prime example of that is you you tend to see quite a lot of bone stress injuries in in football players and soccer players when um they undergo that pre-season training phase right so so they've had a little bit of period of time off they come back and then you you go through this really intensive six eight week period of time where you you go almost from from the lowest loading that occurs during a season i.e the off-season period to probably the highest which is the pre-season period one one after the other so kind of acutely applying those significant changes in training volume and training load that's they're they're the times to start looking out for things for for bone stress injuries it's not it's not a it's not a one-to-one ratio by any stretch of the imagination so you can't necessarily say that they all occur during this time they definitely don't but um you've also got to sort of consider that that a stress fracture is not a stress

fracture is not a stress fracture and what i mean by that is the there are there might be different etiologies towards different types of stress fracture um so an example of that that i give quite often is that ribs let's say the rowers for example suffer quite a lot of rib stress fracture injuries and generally it's thought of that these things are quite biomechanical i.e they're technique driven such that you you're ending up by the technique that the individual is applying you're ending up putting a significant amount of load at a very specific point on quite a small bone within in in the rib but that might be quite a different um etiology and development to a mid-tibial stress fracture for example or a pelvic stress fracture or navicular stress fracture all other common sites in different types of athletes um so again it it gets complicated and of course you may have some genetic predisposition disposition in there and all sorts of different things so it's difficult to say but but definitely the things to look out for are changes in equipment changes in surface acute rapid increases in changes of either load or or duration or intensity um i think one of the other things as far as the bone is concerned that might be particularly pertinent to your um to your audience is is is whether these kind of long slow um relatively low load or lower load types of activity are more detrimental

because they induce a low mechanosensitivity to the bone so if you there are some some studies in rats that that suggest that actually the the bone maximally becomes maximally mechanosensitized quite quickly very short few number of loading cycles few minutes of activity so that the maximum amount of sensitivity of the bone to loading occurs quite quickly and there's also this suggestion that to restore that sensitivity of the bone to load takes maybe a rest period of about you know four five six hours something along along those kinds of lines so actually those kind of high intermittent loads and intermittent i mean with quite prolonged recovery periods might well be best for inducing positive adaptations to the bone um but of course that's that's quite the opposite to what a marathon runner an ultra marathon runner would do they would go out at probably a much lower load and they would just keep that going for a for you know tens of minutes hours etc so you know that there will be still a an initial benefit potentially to that but but do you reduce or minimize or even you know negatively change that adaptive signal by the prolonged low level loading yeah you you've you

you've hit on what i call the four villains that i've seen emerge in my coaching career and i and i've been coaching long enough to have the perspective that each one of these villains has emerged as the big villain at certain points and we've come we've now come to learn that there's a like a synergistic effect between all of them and the four villains are biomechanics as you mentioned when we when we see a bony stress injury we used to just go straight to the biomechanics we're going to throw an athlete on a treadmill we're going to look at their stride okay you know your right stride is longer than your left one or you're landing this way on your foot let's quote unquote fix that new shoes new stride kind of whatever but biomechanics another injury you know another injury quite often changes your your biomechanics and and so that sometimes is a red flag for a bone stress injury you know 100 from a knee injury quite often then leads to a stress fracture yeah 100 but that that was at a at one point in time almost the de facto way that we would look look at bone stress injuries is there was something biomechanically going on and we would try to quote unquote fix that this the second villain is high mileage meaning okay you can only run some magic number 120 miles per week 14 hours per week kind of whatever and we need to keep all athletes below that or when an when we saw an athlete get injured the automatic preventative measure or

countermeasure that we would take would be to reduce their mileage that that was the second villain the the the the third villain as you mentioned and i think that this is starting to get the complexity is starting to increase as we go down the line is the increase in training load or the week what we call that from a technical perspective is the training load ramp rate so you go from 40 miles so you go from 20 miles a week to 30 miles a week that's a 50 increase in load over one week 30 miles a week isn't bad but the 50 increase is that's the villain right we started to look at that and then after that like the final the final villain in this whole story and there might be another one maybe genetics is the fifth villain to emerge in another few years now that nutrigenomics is becoming uh becoming so popular but um uh the the fourth villain that emerged was really the training density so the impulses of the really high training stress whether it's like high intensity intervals or maybe two or three back-to-back long runs and things like that some concoction of that is what kind of produce the bone injury and what i've learned over the course of time that i think your perspective could be really interesting on is it's really a synergy between all of those so if you're going to increase training load you need to make sure that the biomechanical variable or the density variable is minimized so that you're not compiling stress on stress on stress if you

increase the density you do two back-to-back long runs you do two hard runs back to back and that's those are common training strategies amongst a lot of different athletes you need to limit the biomechanical variables you need to limit the mileage variables and you need to limit the the training ramp increase variable so that's like the only sort of mechanical loading stress that that the athlete is kind of undertaking the mismatches occur when you're trying to induce a biomechanical change trying to change their stride they change footwear and you're increasing mileage at the same time like those are the types of things that typically like undo the athletes more than anything else is is what from a practitioner perspective we're we're trying to start to learn it's not any one of those independent of all of them it's the combination of of two or three of them where things tend to go awry yeah exactly i think that's put very very nicely and very succinctly i mean i think yeah you're right i think you know there's there's quite likely to be a genetic predisposition to certain injuries certain types of bone injury and not all by any stretch but but i think you know a lot of these things in athletes can be modified by considering some of the things that we've talked about today i mean but doing that in a practical scenario can sometimes be quite difficult and and particularly in an athlete changing an athlete in a coach's mind particularly one who's maybe already successful doing what they're doing then becomes i i mean successful from a from from a performance point of view then obviously if

if that's the case then changing their mind or looking about something in a different way or you know saying look if you're going to get a stress fracture injury in competition year you're going to be in in trouble and all of those things you know need to need to be weighed up it's not a simple equation by any stretch of the imagination yeah and i've i've honestly i've always looked at uh stress reaction or stress fracture injuries i've always looked at looked at that through the lens of there's some there's some or a lot of human error that caused that very like with other types of injuries or illnesses and things like that like athlete when when an athlete loses training availability a lot of those you you can chalk up to dumb luck not to let coaches and athletes like off the hook with some of those other things but a lot of them like they get sick okay they were exposed to a virus and you know who knows how they got exposed sure they could increase their hygiene and things like that but with the bony bony stress injury you usually can walk back the training and the behavior and the nutrition three four or five weeks and start to look at the patterns and come up with a reasonable conclusion to why that actually happened it's obviously not apparent in real time because you wouldn't have done it in the first place but but when you retrospectively look back at it you're not going to have always the like most crystal clear answers but you can go ah man we really shouldn't have lost a pound while we

induce this type of training stress or kind of whatever it is that's the thing that i think becomes so frustrating with bony stress injuries is not only the lost training availability and as i mentioned on the onset of this podcast they tend to be like season killers because of the severity of them but also the fact that you can look back at it and go crap i really screwed this up yeah and i think that's you know i suppose in some respects they're called overuse injuries for a reason in that sense you can normally go back and think about it which is you know pretty different to a contact fracture for example which you think well it's not not really too much i could have done there's little things but again really as you say that's just dumb luck but no i think you're right i think there generally are things that you can go back and point to um but i suppose at that particular time that's not necessarily your primary focus when you're trying to do that it becomes your primary focus once your athlete has got a bone stress injury it's it's not it's not what you're looking at preventatively i guess right because we tend to look at training through the lens of improvement right how do i improve the athlete the most not through a defensive lens how do i keep them healthy and i think that when we lose that perspective that's when things start to go awry let's we gotta let you go let's leave the listeners with some of those big things though because you've been studying this area for a long period of time and i think that one of the perspectives that that you're kind of entitled to are what are like what are

the what are the big things what are the two or three really critical things that you keep seeing come through your lab and that you keep seeing in the research that if athletes get these few things right they understand these few concepts and they execute them in training they might not be perfect but they're going to prevent a lot of the negative outcomes in terms of bone health what would those be yeah so so i think in terms of what i know for sure not a lot what what i guess my my best guesses are right now i would say are um exactly like you said in terms of those four villains is is avoid kind of particularly those rapid increases in in training uh volume or intensity particularly if you're also trying to combine that with other things that might red flag a a um a bone stress injury risk um i think prolonged low energy availability consistent low energy availability should should be avoided if you if you can and i know that's difficult particularly in an elite endurance athlete population but one of the things that you might start to look at we need a lot more information on this but but i i i do think you know because because telling an elite endurance athlete not to do that it's never going to work

so you can't just say we'll just stop doing that and start eating five kcal pekili around anybody they're just not going to do that it's never going to happen right right so so that's pointless but but what i would maybe encourage people to start thinking about is whether they can periodize low low carbohydrate low energy availability around times where they want specific adaptations that can be brought about by those practices and at other times then then don't do that you know take take the restriction off a little bit and and and try to maintain a higher energy availability um and i guess the other thing is you know take a food first approach to a a normal healthy balanced diet make sure you're getting in plenty of those uh you know micronutrients lots of green leafy vegetables for example and where that isn't a popular dietary strategy then then maybe consider some appropriate supplementation um and i think you know that there may be some some value in considering specific feeding strategies around hard training um sessions and hard training periods um but we really don't know enough about that for me to give you specific guidance right now but but certainly sort of feed and fuel around those hard training sessions would be the best bits of advice i can probably give right now hey that's good enough man

well i i'd love i love it how you know this is dying kruger effect right once you know a whole heck of a lot about a subject you realize that you don't know that much about it but i think in in a lot of instances people like yourself who study this for a living you've been studying it for a long time you tend to under you tend to underplay the things that we have that we do have relatively decent degrees of certainty on they happen they just happen to be the reasonable pieces of advice which ain't sexy it's not gonna you know they're not gonna win an academy award for drama or anything like that i mean if you're saying train sensibly eat sensibly maybe consider some supplementation if things are going awry those are all really reasonable right yeah i mean it's one of those things that i've said before and one of the things i point to is that it's taken me 15 or 20 years of of studying this to realize that all the advice my grandma gave me was pretty much accurate right grandma's always right green leafy vegetable you know those sorts of things it's like yeah fair enough she was right all right man well listen to grandma maybe that's our final piece of advice always craig i really uh appreciate your time before we uh before we say goodbye where can people learn a little bit more about you and uh the research that you do yeah so obviously you can just perform the normal sort of searches for for the papers on pubme just put me in as is the author uh you can google me um i come up my my um institutional so i'm nottingham trent university

here in the uk my institutional link will come up and and you can get access to a lot of the papers and stuff via that direction if you want more information uh i'm on twitter as well so i think i'm at at sale underscore x not if you want to follow me um and and so you know i put out bits and pieces of information retweet papers and retweet you know people who say more sensible things than me and things on there so um yeah that's probably the main probably the main ways to get in touch uh yeah awesome craig well we appreciate your time we appreciate what you have done in the research area and we'll look forward to anything else that your lab and your university produces oh thanks very much for inviting me jason it's been very nice and uh hopefully your listeners get something out of it it'll be great yeah thanks for your time all right folks there you go what a great conversation with craig he was a good sport about it coming all the way from the uk to record this podcast remotely i've had a lot of people from the uk on recently and in the whole world of remote uh podcast recording that we're in right now this is just going to be more and more and more common craig i really appreciate your time and your expertise that you lent to the listeners today and we will look forward to having your wife kirstie on the podcast at some future point to talk about all things related to women's specific physiology had

hoot you guys i hope you did too if you like this podcast go on over to itunes and give it a like or a rating that helps the podcast out a tremendous amount appreciate the heck out of everybody listening today and as always we'll see you on the trails at some point until then stay happy stay healthy and stay safe out there folks