Maximise Performance by Managing Fatigue | Dr Callum Brownstein | The Progress Theory Podcast

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Think fatigue is just about feeling tired? Think again. In this episode of The Progress Theory, Dr Phil Price sits down with Dr Callum Brownstein, physiologist at Newcastle University, to explore the real science behind fatigue—how it works, what drives it, and how to manage it to maximise your athletic performance.

Whether you’re a runner, cyclist, or general fitness enthusiast, understanding why you fatigue and how to recover properly could be the game-changing knowledge you’ve been missing. Dr Brownstein breaks down the difference between central fatigue (brain and nervous system) and peripheral fatigue (muscles), and how training type, intensity, and volume can impact both.

If you want to stop guessing and start training smarter, this episode is essential listening.

In this episode, we explore:
🧠 The difference between central and peripheral fatigue
🚴‍♂️ Why cycling and running create different fatigue profiles
📈 How intensity and volume affect recovery
🗓️ How to organise your training week to reduce overload
⚖️ Pre-fatigue strategies and training session sequencing

Episode breakdown:
0:53 Introduction
8:34 Central vs. Peripheral Fatigue Explained
12:15 How to Identify Your Type of Fatigue
16:42 Running vs. Cycling Fatigue Differences
21:29 Which Type of Fatigue Recovers Faster?
23:42 Structuring Session Order for Better Recovery
26:13 Impact of Intensity and Volume
30:47 Practical Training Recommendations
33:41 How to Build a Smarter Weekly Plan
35:32 Pre-Fatigue Training Explained

Key Takeaways:
🔬 Understanding Fatigue Mechanisms: Know the difference between brain-driven and muscle-driven fatigue to improve your recovery and planning.
🔁 Modality Matters: Running often leads to central fatigue, while cycling triggers more muscular (peripheral) fatigue. Train accordingly.
🧘 Discipline in Intensity: Keep easy days easy—going too hard too often is a one-way ticket to burnout.

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@drphilprice (https://www.instagram.com/drphilprice/)
Callum G Brownstein on X (https://twitter.com/CGBrownstein)
Newcastle University (https://www.ncl.ac.uk/)
David Bishop on Google Scholar (https://scholar.google.com/citations?user=dZLPqkoAAAAJ)

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#TrainingRecovery #ExerciseScience #HumanPerformance

hello and welcome to the progress theory where we discuss scientific principles for optimizing human performance i am Dr phil Price and on today’s episode we’re joined by a physiologist from Newcastle University Dr callum Brownstein now managing and recovering from fatigue is so important for the success of a training program and sporting performance so if it’s that important we really should understand the mechanisms behind fatigue and on top of that we need to understand how different sports different training modalities and different training intensities different training volumes all influence the type of mechanisms behind fatigue and if we can understand that we can make better training programming decisions as always follow the progress theory on Instagram and YouTube and check out all of our other content here is Dr callum Brownstein hi Callum how are you thank you for coming on to the Fergus Theory no problem thanks a lot for having me on really good to have you on i first heard of your work funnily enough uh we have uh a TMS at St mary’s University and I’ve been asking one of our researchers there Alex Woodhead all about it because I wanted to learn more about fatigue and then he provided me with some resources uh and it was some slides and a PhD and it was your PhD which you must have or a particular chapter from a PhD um okay and so I was like hm okay and then I heard your uh podcast on that triathlon show i was like okay this is my turn now right brilliant no happy happy to come on yeah absolutely for those who are not familiar with the fe fatigue and research do you want to just introduce yourself like um your sort of research background that type of thing yeah sure so uh I did my PhD at North Umbrea University uh so I finished that in 2018 and my PhD was in the area of I’ll call it neuromuscular fatigue ability so the acute impairments in neuromuscular function occurring as a result of exercise um and in particular was looking at recovery post exercise after highintensity intermittent team sport type exercise so we were looking at football match play the focus of the PhD was especially on changes occurring within the nervous system as a result of exercise uh how they can perhaps contributed to fatigue ability so to you know impairments in force and power generating capacity and how long they took to recover um post exercise because prior to that when we think about post exercise fatigue and recovery the focus had primarily been on sort of peripheral muscular changes and how long they take to recover so mechanisms like muscle damage and glycogen depletion and inflammation um whereas although we knew that the nervous system can contribute to fatigue ability to impairments in force generating capacity during exercise there hadn’t been much research looking at that in terms of recovery so how long those mechanisms took to to recover following exercise um so that was what my my PhD within so it was really a a kind of neuromuscular neurohysiology focus and then I moved across to France uh for four years where I worked uh under the supervision of professor Gam Mier so I’d never really planned to move abroad but the opportunity came up towards the end of my PhD uh I knew of Gam’s research really well i knew we had really similar interests and I knew that you know it was a great opportunity to work in his lab because I knew how productive his labs were um and yeah it was a really brilliant experience absolutely loved living in France and working in the lab and during my postto I probably transitioned a little bit so there’s there was probably a phase in my postto when I was like you know there was a lot of neuro kind of pure neurohysiology research going on in that lab as well as exercise physiology research so the neurohysiology research would be looking at kind of nervous system function and changes within the nervous system but not necessarily in response to exercise but it was really the exercise side of things that um that I was interested in and so I I probably transitioned a little bit away from just neurohysiology and starting to look more at the integrative responses to exercise with an emphasis on studying the neuromuscular system within a sort of integrative exercise physiology framework so since then uh my research sort of revolves around studying the acute responses to exercise what limits the physiological responses to exercise and again studying fatigue ability in a kind of integrative exercise physiology framework and now you’re at uh Newcastle University is that right yes yeah I should add that yeah yeah so I took up a lecturing role at Newcastle University in September 2022 so I’ve been there um going on two years now um so yeah usual lecturing post to do um teaching and and have plenty of time for research as well so um no it’s it’s been really good since I’ve started started here did you play any particular sport growing up that led you to well towards the research around sort of fatigue and physiology when it came to like starting your PhD i boxed competitively and amateur boxing when I was about 14 15 years old and it was probably that that really got me interested in I guess physiology and sport science and kind of um being curious about what were what are the sort of optimal ways to train because boxing’s an individual sport you obviously have to be very fit and I I did often think with some of the the training that I was doing back then when I was going to the boxing clubs that you know you’d spend say you’d have a 2-hour session you’d spend the first half hour skipping and you’d go on slow runs and stuff like that and then you you’d have a a bout and it would be you know three two-minute rounds very very high intensity so I was always like well what we what we’re doing in training doesn’t really replicate what we’re doing when we compete um so I I became kind of curious about it and um so decided to do an undergrad in sport science um when I started my undergrad I actually wanted to be a practitioner so I wanted to work with athletes and I especially wanted to work in football because I was a big football fan um so I kind of worked towards that during my undergrad and ended up working at a a football club in Edinburgh for a couple years so during the last year of my undergraduate and then I did a masters by research with the football club so that was at Harry W University where the the football team trains um and I enjoyed being a practitioner and kind of working with academy players but I really enjoyed doing research so whether that was you know with the players or uh or my undergrad dissertation project um and I felt that that was the route that I wanted to to go down and then the PhD position became available at North Umbrea and it was kind of there were similarities or overlap for what I was doing during my masters by research so yeah I felt like um yeah that was a career path that I wanted to to go down rather than being a practitioner m that’s cool to hear i when you said that your research really focused around sort of high intensity bouts of exercise and how uh what type of fatigue is generated from that and how well we can recover from that uh the first thing that came to my head is like you’ve done a particular sport which involves sort of like highintensity movements for a particular amount of time so when you talk about boxing and football I was like “Oh okay.” It’s sort of you can always understand where people sort of like research passions come from because something’s happened before so it’s like something’s there i was like “Okay yeah boxing makes a lot of sense especially if it’s like you know really intense bouts of work.” So well what happens from that you know cuz I realized earlier I said TMS and they’re not exactly frequent um so do you can we start at the beginning and then would you be able to just kind of give like a base understanding of the difference between let’s say central fatigue and peripheral fatigue all right so I suppose the way that I try and think about it and the way I try and encourage my uh students to think about it is there’s a lot sort of debate on how to define fatigue but let’s just say for the purposes of today that fatigue is uh a reduction in the force generating capacity of the muscle so you you ask someone to um contract with as much force as possible before and after exercise and there’s a reduction in how much force could be generated or maybe maximal power depending on how you’re measuring it so the way I I try and think about it is in order to understand what contributes to muscle fatigue in response to exercise you need to understand or what the mechanisms of a muscle contraction are because it’s the interference with those mechanisms that contributes to muscle fatigue reduction and force generating capacity and a muscle contraction begins in the nervous system that’s where those signals are initiated so we have an area of our brain called the motor cortex and that’s the area from which uh descending signals are sent from the brain to the spinal cord where they then activate what are called alpha motor neurons in the spinal cord and those motor neurons project to the muscle they kind of branch and they innovate a given number of muscle fibers um so a motor neuron and the muscle fibers that that motor neuron innovates are called a motor unit so for example if we’re talking about the quadriceps there’ll be you know several hundred motor units each motor unit will have several hundred sometimes you know maybe over a thousand muscle fibers within each motor unit so we’ve got the signal coming from the brain to the motor neuron to the motor units that signal then projects to the muscle it reaches the muscle and then it initiates a kind of cascade of events in the muscle which lead to muscle contraction so if we’re talking about central fatigue this refers to reductions in the capacity of the nervous system to activate the muscle the strength if you like of those neural signals going from the brain to the muscle are reduced and that means we’re we’re unable to activate the muscle completely and that can contribute to reductions in muscle force generating capacity so that’s what we would term central fatigue and then peripheral fatigue so impairments in contractile function this is a reduction in the capacity of the muscle to respond to those nervous system signals so once the nervous system signal arrives at the muscle fiber it initiates those you know that cascade of events which results in the the generation of force and if there’s impairments or changes occurring within the muscle itself uh then that can also contribute to a reduction in force generating capacity so those are the two general mechanisms of muscle fatigue but then there’s like I say they’re general mechanisms so there’s a lot of things going on there can be a lot of different mechanisms within the nervous system that could contribute to a reduction in voluntary activation and there’s a lot of different mechanisms going on within the muscle that could contribute to peripheral fatigue and impairment in contractile function and the way that we can measure that so we can measure those two general mechanisms uh and the way that we do that uh is using electrical stimulation of the motor nerve so usually if we’re looking at kind of whole body exercise like cycling or running uh the quadriceps are usually the muscles that we focus on terms of the knee extensor muscles because they play a central role in in activities like running and cycling and they incur a lot of fatigue in response to those types of exercise if they’re high intensity or prolonged so the way that we do that is we we stimulate the motor nerve and that would be the femoral nerve if we’re talking about the quadriceps because that’s the nerve through which signals are sent to activate the quadriceps muscles so the way that we measure voluntary activation is we ask participants or we have participants performance called an isometric contraction so that’s when they’re trying to extend their knee um but there’s there’s kind of it’s against an immovable object and you’re measuring how much force is generated during that isometric contraction so we have them produce as much force as they possibly can and when they’re at their peak force so when they’re at you see the plateau in the signal you then deliver an electrical stimulation to the motor nerve so to the femoral nerve if it’s the quadriceps if the nervous system isn’t activating the muscle completely through that voluntary contraction then when we stimulate there’ll be a uh what’s called a superimposed twitch so there’ll be additional force invoked on top of the voluntary force and that tells us that the the nervous system has been unable to activate the muscle completely and so that’s if we if if the size of that additional force that we get on top of the voluntary force with the stimulation increases for example in response to exercise that tells us that there’s been a reduction in the capacity of the nervous system to activate the muscle so that tells us about that nervous system component of u muscle fatigue and then what we do is we have participants relax straight after that maximal contraction and we deliver the same electrical stimulation but this time at rest and again that will evoke what’s what’s called a a resting twitch response so this time there’s no input from the nervous system because the participants are relaxing so there’s um you know they’re at rest and the stimulation is traveling from the motor nerve to the muscle uh and we get that twitch and if there’s a reduction in the size of that twitch then that tells us that there are there’s impairments in contractile function so that would be our measure of peripheral fatigue uh and so together we can use these methods to to quantify muscle fatigues through the reduction in um the maximal force and those two general mechanisms through voluntary activation and the breast to twit response now that’s really cool and this is this type of physiological testing and measuring fatigue and the you know both the central and peripheral uh mechanisms I mean that’s been done for quite some time in terms of looking at different sports and different volumes and intensities of work am I right yeah absolutely yeah I think especially in the you know the last 20 years there’s been a lot of research out there you know prior prior to uh kind of in the ‘9s and before that there had been plenty of research using these methods but they had primarily been done using isometric exercise so obviously when even if we’re looking at whole body exercise using these methods we’re quantifying muscle fatigue using isometric contractions because it’s a very valid and reliable way to measure muscle fatigue and we can implement these stimulation methods but kind of in the ‘9s and and before um it they were using isometric exercise to induce fatigue and it was probably only since the millennium that uh since after the millennium that a lot more research had gone into measuring muscle fatigue in response to more ecologically valid types of exercise like uh endurance running and cycling and team sports um and um yeah but take the types of activities that people would perform on a daily basis especially quite a lot of the literature that I’ve been particularly interested in have talked a lot around the differences in fatigue that’s been evoked if you did cycling over running so I guess I’ve been reading a lot around concurrent training and around you know the combination of strength and endurance training and there’s a lot around well if you don’t want to have some kind of interference effect maybe should choose cycling over running because of the the fatigue response um what are the like main differences in fatigue response if you compare cycling and running and I realize that’s quite a broad question because with each sport comes with different intensities and volumes but what are the main differences between those two modalities really one of the central areas in this in kind of research looking at fatigue ability in response to whole body exercise just any type of exercise really is what’s called task dependency uh and that basically refers to you know the magnitude of and mechanisms contributed to muscle fatigue differ depending on uh the characteristics of exercise that we perform so that can be you know the exercise intensity the exercise duration or like you’re referring to in cycling versus running the exercise modality so all of these factors can have an influence on again the magnitude and the mechanisms contributing to muscle fatigue so we did a study a couple years ago uh it was one of the last studies I did during my posttop where we tried to address that question of what are the differences in in fatigue or the magnitude and again magnitude and mechanisms of fatigue between running and cycling uh so we recruited uh they were primarily triathletes so they were people who were very much familiar with uh both modalities so we had two separate visits uh where they performed three hours of cycling for during one visit three hours of running during another visit uh and importantly we matched the intensity and obviously the duration was 3 hours but it was important to match the exercise intensity between the two modalities uh it kind of if we didn’t do that appropriately then you know you’re confounded by differences in the intensity so we had them cycle and run uh at uh it was just above the lactate threshold so it was 105% lactate threshold or we measured it using gas exchange so the gas exchange threshold uh and then we quantified using those methods that I described uh muscle fatigue and uh voluntary activation so that’s central fatigue element and contractile function that peripheral fatigue element we we measured that pre-ex exercise halfway through exercise so at an hour and a half uh and post exercise and so the results were quite interesting because we found that muscle fatigue so the the magnitude of the reduction in the force generating capacity of the knee extensors so muscle fatigue was very similar between the two modalities so there was no difference between the reduction in force generating capacity was something like 25% around about that but the mechanisms that contributed to that decrement were very much different between the two modalities so in cycling we found quite substantial reductions in the resting twitch response uh and some reduction uh in voluntary activation as well but it it looked like that the the fatigue incurred from cycling was primarily a result of mechanisms within the muscle and in contrast in response to running we actually found very little decrement in the resting twitch responses so that peripheral fatigue element but really quite substantial reductions in voluntary activation i guess the results suggested that you know both cycling and running at a given intensity and duration incur similar magnitudes of muscle fatigue but the mechanisms differ nervous system elements are relatively or nervous system contributors to muscle fatigue are relatively more important in response to running whereas those peripheral mechanisms seem to be more important in response to cycling so um yeah there was really quite clear differences there so it was interesting that’s really interesting how very different or different mechanisms or different proportion of mechanisms yet the output was still the same there’s still around that 25% decrement in force production i I I do wonder if this might be quite individual but is there a type of mechanism which we recover from more quickly so for example in that study you described where you had 3 hours of running and 3 hours of cycling because the cycling had more peripheral mechanisms would you recover faster because they are peripheral fatigue recovers quicker or the other way around more central factors recover quicker or is it more of the same it would have been interesting to have uh measured recovery we didn’t measure recovery in that study i mean I think that recovery is probably more prolonged in response to running versus cycling because you’ve got those it’s a much higher mechanical demand in response to running you incur quite a lot of muscle damage in response to running so I I suppose the way I try and think about recovery is what are the mechanisms that contribute to uh muscle fatigue and how long do those take to dissipate so I think that in response to cycling you know if you if we had taken a biopsy from the quadriceps after that 3 hours of cycling we probably would have found very low muscle glycogen levels and you know with you know appropriate nutrition and taken plenty of carbohydrates on board I would imagine that around 24 hours maybe 48 hours later that would have returned to baseline and that was probably I think one of the main mechanisms contributing to that impairment in contractile function that we were seeing in response to cycling again with appropriate nutrition I think after metabolically demanding exercise with a lower mechanical demand glycogen reynthesis is is relatively rapid and your recovery of neuromuscular function is relatively rapid whereas in response to running because you’re incurring one you’re occurring incurring a lot of muscle damage which takes much longer to recover you’ll still have a lot of glycogen depletion but that muscle damage that you’re incurring also interferes with glycogen reynthesis um so yeah I think definitely recovery is is more prolonged following running based exercise as a result of those higher mechanical demands yeah that does make sense like um I would always compare it to especially say concurrent training which have found like a decrement in strength performance and it kind of makes sense as yes you’ve got different I guess mechanisms at play when you’ve got different modalities when it comes to fatigue but uh I mean assuming and this is probably a follow-up question if you did very high intensity strength work that would place a large demand of possible fatigue mechanisms of of the central nervous system or more central uh factors so because there the mechanisms are similar for running and sort of high intensity strength work that’s why it might affect high intent high intensity strength work more than say cycling which the mechanisms are more geared towards peripheral i’m not an expert in this kind of resistance training research but um you do often hear about people sort of equating high intensity strength training and and the central fatigue induced by that but to be honest I’m not I don’t really know of any research that’s really looked at that or actually demonstrated that it’s the case um but I think you know heavy resistance exercise in this similar to running will um induce a lot of muscle damage which again will take more a more prolonged period to recover from and there is also research showing that muscle damage per se you know can have quite a strong influence inhibitory influence on the nervous system so you’ve got studies which use um you know eccentric damaging protocols so these are are protocols designed to destroy the muscle basically just um evoke as much damage as possible and then they use these sort of methods I’ve I’ve described um previously they quantify kind of central fatigue and reductions in voluntary activation can take quite a long time to recover um after that sort of exercise sometimes you know two to three days so yeah I think heavy the bounce of resistance exercise which uh induce a lot of muscle damage can induce you know quite substantial and quite prolonged impairments in nervous system function definitely is interesting that um that seems to be a direction of research which is yet to be trodden or we don’t fully understand at the moment that’s really cool there’s another particular study I I remember and it looked at cycling intervals and I guess peripheral and central fatigue uh factors were measured after each interval and I just remember this particular graph very clearly that after each interval peripheral mechanisms of fatigue were increasing kind of steadily and central fatigue mechanisms were kind of near zero they you know weren’t really contributing much and then once they reached almost like a certain threshold of number of intervals central factors just went like exponentially went up so and I I assumed there’s always this relationship between intensity and volume when it comes to different factors that play when it comes to fatigue is that something that you found in the research as well that when it comes to sort of low intensity versus high intensity you get different responses but when you do high volumes of high intensity all of a sudden both factors both peripheral and central mechanisms increase quite a lot yeah I think I know exactly the study that you’re referring to as well i think that was one of posttop supervisors uh where they looked at kind of fatigue during highs and intervals i couldn’t couldn’t remember the name but I just remember that graph vividly yeah yeah yeah so that’s a very much consistent finding throughout the literature kind of no matter where you look um studies that measure sort of the kinetics of of fatigue ability uh will during not necessarily prolonged because I wasn’t prolonged exercise but there were quite a few intervals you will almost always find that those peripheral mechanisms so those reductions in rested twitch responses they occur very early during exercise um and then they’ll often reach a kind of nadilla so they’ll stop decreasing and at at that point you then generally see you know reductions in voltry activation so the reductions in voluntary activation in that nervous system component of muscle fatigue are more kind of predominant when exercise is more prolonged so there’s a relationship between exercise duration and reductions in nervous system voluntary activation so the longer the exercise is generally um the greater the reductions in involuntary activation what’s interesting is that we we don’t really know why that’s the case at all i would say um you kind of people might speculate about different things but I would say that we don’t really know why that occurs the nervous system is not as easy to study as the muscle because you can take a biopsy of the muscle you can use other methods like magnetic resonance spectroscopy where you can look at what’s going on inside the muscle during exercise you can’t really you can’t take a biopsy of the nervous system obviously so it’s much harder to work out you know what’s going on we we can use other methods so one of them you mentioned earlier is um TMS transcradomagnetic stimulation um uh we can do spinal electrical stimulation and so we can kind of try and probe what’s going on within the nervous system by stimulating the nervous system at different sites but we don’t we don’t really know why it is that reduction of varyra activation occur um or become uh greater as exercise duration increases but there’s you know lots of evidence showing that that that’s the case and then in terms of those peripheral mechanisms they they certainly become more well they become greater as exercise intensity increases and sort of a very important threshold for peripheral fatigue is um the maximum metabolic steady state which we often measure with uh critical power so when we go above that critical power into the severe what what we call the severe intensity domain um because there’s these uh substantial and rapid uh metabolic perturbations so there’s these increases in metabolic concentrations so things like an organic phosphate or um ions like hydrogen which contribute to peripheral fatigue you know the muscle will fatigue at a rapid rate as a result of those mechanisms so um yeah definitely intensity and duration have an important influence over those kind of general mechanisms of muscle fatigue are there any practical recommendations that have come from that research to the point where you kind of want to train hard but not to the point of too intense or when you get to that nadier so that you can kind of train more frequently yeah has there been any practical recommendations come from your ability to recover from different mechanisms you know there’s a lot of stuff out there at the moment on how they call zone 2 training and all that and basically keep your easy days easy and make your hard days hard sort of thing and yeah some of the research we’ve done is looked at the relationship between exercise intensity and and muscle fatigue and we did a study a couple years ago looking at fatigue around the the lactic threshold or we measure it with gas exchange the gas exchange threshold so that’s the intensity above which lactate blood lactate will increase for the first time so it’s the boundary between moderate and heavy intensity exercise um and what we show so that would kind of be I guess well you’ve got all these different zone models but if zone two was just below the that threshold and then zone three was kind of in the heavy domain just above it so what we found was that when you cross that threshold quite early during exercise muscle fatigue is kind of compounded and quite substantially greater than when we’re just below that threshold um so even yeah being above that threshold for a really fairly brief period of time causes kind of exacerbated muscle fatigue so I guess a practical takeaway from that is it kind of re-emphasizes that keeping your easy days easy and if you’re on a sort of what you’d call a recovery run just being disciplined with your your exercise intensity to to kind of preserve your your energy and your physiological function if you like for those those higher intensity sessions um because probably the recovery cost of of crossing that threshold for even relatively brief periods of time is going to be greater versus if you if you stay below that threshold now that does line up with a lot of what is being perpetrated out there regarding keep your easy days easy uh and how many people especially in running they end up not running intensely but they run their easy days too hard so they’re like stuck in that zone three if it’s I guess a five zone model heavy domain uh and so they’re just compounding that fatigue and never really do anything easy so they’re trying to they think they’re doing their their they think their easy days are easy but they’re not they never actually have an easy day and so that companion fatigue just builds up over time and that’s where the problems happen absolutely it’s all coming together it seems all they’re saying and the research supports that you know yeah definitely do you have any other practical recommendations in terms of how to organize a training week uh based on you know your intense days and your easy days based on how well you know that we recover from certain exercises certain intensities that type of thing yeah I I think it’s just it’s probably doesn’t have to be rocket science to be honest i think um so myself I’m definitely not an endurance athlete but I will make sure that I’m as as fresh as possible for those high intensity days so for those days when I’m I’m you know I’m I’m spending time in the severe domain and I’m doing high intensity intervals or uh perhaps uh you know a 5k run I’ll make sure that I’m as fresh as possible going into those days um so it might be that the day before I’ll have a day off or it might be that again I I would do a sort of moderate intensity run uh in the days before that um so I think it’s just but some of it is trial and error knowing how long it takes you to recover from certain types of sessions and I think once you you kind of know yourself when how long it roughly takes to you to recover from certain times of uh sessions and um so that you feel at your best going into those high intensity sessions so it’s very individual though so I would say it’s hard to give you know very kind of prescribed guidance um but yeah I would say just ensuring that you’re as recovered as possible for those high intensity kind of red zone sessions um by yeah again making your easy days easier in the in the leadup to that really there’s something that’s quite popular in the training space at the moment where you are deliberately trying to elicit a form of fatigue which I believe is more of a peripheral uh fatigue where you would train movements which are similar to say running so you’re doing squats lunges all of those types of things and you’re kind of lightweights training to failure in in a circuit type of training and then you’re utilizing that fatigue to then do your long endurance session the next day so the idea is that you’re kind of like running on fatigued legs and it’s a strategy I’ve seen people use as a way of well I want to get better at my long-distance running but I don’t have the time to uh run as much as a long-distance runner and I’m usually a bit more heavy so I’m using this strategy of pre- fatigue to try and uh use that when I do my long runs and then once I sort of reach a particular race or something like that and I start to ease off the the pre- fatigue and stuff and I start to go in more fresh to these long runs I then carry that fitness and I’ve actually improved have you ever heard of uh sort of like a pre- fatiguing type of exercise strategy uh and do you think that would be beneficial for let’s say long-term endurance performance for athletes that might be a little bit heavier or you know they’re not just runners i can’t really say that I’ve heard that strategy in particular i suppose what it makes me think about is um there’s a lot of stuff coming from David Bishop’s lab so he does a lot of research on mitochondrial adaptations to endurance exercise and one of the things that he looked at was looking at kind of double sessions basically so so training twice within one day which I guess is somewhat similar because you’d be probably going into that session with um some degree of of fatigue so yeah I guess if and yeah I know that some of that research has shown that the mitochondrial adaptations can be enhanced um through doing double sessions so two sessions within one day relative to kind of performing this the same number of sessions in a week but not two in one day so more spread out so I guess what it makes me think is that um you know it’s maybe not any positive adaptations coming from that or maybe not as a result of fatigue per se of going into a session fatigue per se it’s probably just you’re increasing the kind of training volume becomes higher by by doing those sort of double sessions or or going into a session fatigue because you you’ve recently done a session and there there’s positive adaptations associated with that which probably aren’t as a result of of fatigue per se but probably as a result of the high training volume as a physiologist I always focus on the physiology obviously but maybe there could be some benefits in terms of um you know training under fatigue perhaps psychological benefits of that because you know eventually during a race especially if you’re doing more prolonged distances like ultramarathons at some point you’re going to you know have to run over quite extreme fatigue so there’s perhaps some psychological benefits of of having done that at certain phases of kind of your your training cycle i think there could be benefits there no that’s really interesting and you know you seeing it more and more with especially with elite athletes they’re getting so good but they seem to be able to recover so quickly for such high training volumes and training volumes are so high that they are doing like double session triple sessions per day you’re like is that fatigue just completely building and now people are utilizing it specifically because they believe that that’s going to lead to a specific adaptation so it’s interesting what you’re saying that you know you’re you’re deriving fatigue but isn’t the fatigue that might be causing the improvements it’s it’s just providing like an environment for something else so yeah that’s really interesting to start think about that’s really cool yeah yeah so I thought it’s you know fatigue is just an inevitable consequence of of having such a high training volume but I don’t think it’s the fatigue per se that’s eliciting the adaptation there’s perhaps like overlap between mechanisms that are contributing to muscle fatigue and mechanisms that are initiating those kind of intramuscular intracellular signals that are eliciting the adaptations if if that makes sense yeah definitely so so in order to so in order to you know improve and elicit those adaptations you know muscle fatigue is sort of inevitable callum that was absolutely amazing you really did answer my questions and I’ve got a list here that I’ve literally just gone through everything has been absolutely great thank you for all of that information um where can people uh reach you especially when it comes to like um you put up your research yes so I always uh put my research on Twitter uh so Twitter handle is CG Brownstein um so yeah you can find me on on Twitter and um yeah I always put all my research there uh you can find a link to my research gate there as well so um yeah those would be the main channels yeah brilliant if anyone’s wanting to learn more about fatigue and all of that please definitely check out uh those pages i I found a lot of great work on your Google Scholar page as well so um and yeah I recommend if you’re interested in fatigue especially around how you might be able to derive some practical applications in terms of how you orderize you order your training week etc etc definitely check out that workbook callum yeah thank you so much for coming on no problem thanks a lot for having me [Music] [Applause] [Music] on Heat [Music] [Applause] [Music] [Applause] [Music]