Evidence Strong
Health risks of holding your breath while lifting - with cardiovascular expert Kate Drury
like really what we found was that the cardiovascular adaptations that were occurring in the power of things that we studied weren't necessarily a training adaptation per se. It was more a combination of they were already skilled at this particular task we were asking them to do. They already held a lot of trunk muscle mass, which then we know is correlated with respiratory muscle strength and the ability to generally take big breaths and generate a large amount of respiratory pressure. So I think that you know if people were just being generally helpful doing their cardio, like doing their cardio, keeping reasonably fit and well, I don't see how that would negatively impact your ability to continue to generate high intra thoracic pressures in order to splint to do a big lift. I mean if anything, if you had good cardiovascular fitness, I would speculate that you'd just be able to take bigger breaths and hold them for a longer amount of time and then thus generating more intra thoracic pressure. Okay Kate, welcome to evidence-strong show. It's my pleasure to have you and please introduce yourself briefly. Yeah sure, so my name is Kate Drury. I'm a cardiovascular cardiopomeric physiology researcher. I'm also a powerlifter so I've competed in powerlifting for about 10 years and so basically how I got into this type of research was I have quite a multidisciplinary clinical background. So I'm a clinical nurse specialist in emergency nursing and also an accredited exercise physiologist and basically why I was interested in vascular physiology was I was seeing it in a few different contexts. So we actually used our salvers in emergency to revert agrichneers and I was basically thinking wow we can have this profound impact on the cardiovascular system just by modifying our breathing. So I wonder how, you know, how that impacts the cardiovascular physiology of people who do it just in an athletic sense because you know powerlifters, weightlifters, people who resistance train use valsala minimus all the time. So that basically led to my Master's thesis which was looking at cardiovascular adaptations to repeated valsala minimus in palipas and basically the paper that we're going to discuss is the product of that study. So that's me. Cardiopulmonary clinical type stuff is my interest. Amazing. I have spent a few months looking for researcher like you so I'm super excited. I will just mention them explicitly the name of the paper, effects of intensity and training on cardiovascular responses to the valsala maneuver. So that's right. We are discussing and I think we have to start at the beginning and discuss physiologically what valsala maneuver is and what happens mechanically and in terms of reflexes or autonomic response. Let's go science. Yeah, absolutely. Cool. So I'm just going to share my screen to show you a diagram. Awesome. So for anybody who is wondering where this diagram came from we actually drew up an idealized response to valsala minimus based on our literature review and some of the pilot work that we were doing in the lab and this actually is pulled from one of our figures in the paper. So if you've read the paper you will recognize it from the methods. So basically what you're looking at here is on the y-axis you've got the cardiovascular response and we're looking at two different responses within the same plot. So the blood pressure which we about blood pressure globally they're both systolic and diastolic blood pressures behave the same way within the valsala maneuver. So your blood pressure there is the dotted line and that's obviously measured in millimeters of mercury. And then the solid line is the heart rate response measured in between the. Could you just clarify for everyone what is the stolic and diastolic blood pressure? Yeah, absolutely. So most people know that their blood pressure is made up of two different numbers. So the systolic blood pressure is the number on the top. So you might keep people talk about say their blood pressure being 120 over 80. So 120 is systolic blood pressure and systolic means that that's the you know the resistance exerted on the vessels when the heart's in systole or when it's ejecting blood and the diastolic blood pressure that what a number on that equation the 120 out of 80 is basically the same thing the amount of pressure exerted on the arteries but when the heart's in diastole so when it's relaxed and in its filling phase. So it just looks at the two different components of the cardiac cycle in ejection and relaxation. Thank you. So that's our y-axis and then along the x-axis down the bottom we're looking in time in seconds. So in the research context obviously we have to be super controlled in the methods that we take in doing stuff like this. So when I talk about valsalva physiology we're looking on a time force of about 15 seconds. Obviously when we're out in the gym and doing our different lifts and stuff our valsalvers can last for a varying amount of time but in the research context we just have to make everybody do it the exact same way every single time. So that is still a little bit of an unknown. We don't know a lot if the cardiovascular responses are exactly the same in shorter time forces or longer ones but if you look at the valsalva physiology research more broadly on 15 seconds is a really standardized time period. All right, cool. So if we have a look at our graph basically this flat line is before you've started the valsalva so you just normal breathing pattern in your you know your breathing and your heart rate and your blood pressure or controlled by respiratory sinus everything you are which is a normal physiological process where basically as you breathe in your heart rate trends up and as you breathe out your heart rate trends back down. So that's our baseline and what will happen is as all lift is know you take that really nice big breath in, fill your thorax and your abdomen with air and then you basically splint out isometrically in your abdomen and/or a belt. So that's when the valsalva begins when you begin that isometric hold and you're sort of doing a isometric isovalumic expiratory breath. So we've cut the valsalva into a few different phases here. So phase one if we look at the top here that's basically just a few cardiac cycles long so a few heartbeats and what's happening there is you're getting that big rise in intra-thoracic pressure and that is starting to build compression on the heart itself and the roots of the great vessels. So those are things like your aorta, your pulmonary trunk, your superior and inferior vena cava because they sit really nice and tightly around in your central circulation. So as we build that big intra-thoracic pressure the heart and those vessels start to get compressed. So because they're being compressed the aortic pressure goes up and then you get a little bit of a compensatory decrease. So that's kind of what we're seeing here is this increase in the blood pressure and a decrease in the heart rate. Then you're going to move into phase two. So remember that phase one is really short, only a couple of cardiac cycles. So we're into phase two now and then this is the main chunk of the vals of a maneuverate cell. Now because you've got that ongoing intra-thoracic pressure that compression on the vessels your vena should turn and your cardiac output are now compromised. So that amount of blood volume is becoming reduced and you can see between phase one and phase two there's now a reciprocal change. So the blood pressure is starting to turn down and the heart rate is starting to turn up. That's you know a result of aortic pressure now decreasing so that's why the blood pressure falls and then you get a compensatory behavior in the heart rate. That's you know reasonably transient. It's physiological not pathological so we don't need to worry too much. So as I said in the research context we're looking at this on a time course of about 15 seconds. So we told our participants to let go of their vals up and maneuver at the 15 second mark and that's what indicates that we're now into phase three. What's interesting about phase three is that the cardiovascular system is still responding even though we've taken the expiratory stimulus away. So we've got intra-thoracic pressure is now moving back down towards baseline. Not all the way back yet but it's on its way down. That means that that pressure on the aorta has come back down as well and you're seeing another drop in the blood pressure. It's a little bit goes down even further than what it was in phase two and again a nice little compensatory rise in the heart rate. Much like phase one this one is quite short too and what we see then is the movement into phase four. Now we don't know when I say we I mean like the royal we in terms of cardiovascular scientists nobody really quite knows exactly how long before phase four lasts for. It's kind of speculated that it might have something to do with the cardiovascular health of the participant at a baseline. So people who are generally a bit healthier have more elastic vessels would probably return to phase four a bit quicker but it's not kind of objectively saying like yeah at this time point you would be in phase four or return to baseline it's just a general trend back. So what happens by the time we get to phase four is the intra-thoracic pressure rise is basically totally dissipated. You're back on the way to your baseline however much pressure you would normally hold in your chest and what that means is then all that venous return that couldn't return before is going to surge back into the central circulation. So you get a nice big sweep up in the blood pressure and then the heart rate slows down to try to accommodate that excess blood volume. That being said you know there are some variables in depending on who you're looking at what kind of time it was but generally this is what we would expect to see in a normal healthy person lying down doing a controlled valsap in an era. One of the questions that I did have when we were kind of running this study is this doesn't actually have for any changes in postural. So in the research context obviously people are attached to a whole lot of different stuff you know we had 12ccg we had in the arterial blood pressure we were also doing echopardiography on all of our disciplines. So it meant that they were all lying in a semi-recomment position but people don't power lift or Olympic lift in the semi-recomment position. So there are still some remaining questions about if this cardiovascular behavior would change it or for example if the person was lying down doing a bench press or if they're bent over doing a deadlift because obviously your posture has a little bit to do with the way that your blood volume is distributed so that's still a question that's hanging in the air. Yes thank you so just to clarify face one is the face one starts from the moment that you hold the breath so the inspiration part kind of precedes that so the inspiration would kind of occur here before where that dotted line is that's when the expiration would start or the actual valsap and maneuver itself so all the things that are occurring between these two vertical dotted lines is the expiration or valsapha. Okay awesome and three and four is response after the maneuver is finished correct so face three starts as soon as you let go of that breath where you're trying to like return to your normal breathing pattern. Awesome okay this is clear so now could you tell us what you exactly did in the study who were the participants and all the details of metal section. Yeah absolutely so basically in the study what we did was recruit palletors who had at least three years training history we wanted the difference between the two groups to be as clear as possible so we excluded anybody who was kind of recreationally doing resistance training exercise because we know that you know when people go to the gym even if they're not trained in valsalva often subconsciously they'll find themselves holding their breath through the difficult part of a lift and we didn't want that at all so the sedentary group was made up of people who didn't exercise at all they could play kind of like recreational team sports you know go for a walk for general health and things like that but we didn't want them doing any kind of rigid exercise so the sedentary group were completely sedentary from a resistance training point of view and the palletors had a three-year training history couldn't be on any performance enhancing drugs or anything like that they also had to have a regular menstrual cycle so we could test them when in the first three days of their follicular phase no smoking no alcohol on a regular basis so participant wise what we wanted was you know 18 to 50 had been in the sport for at least three years were reasonably regular competitors so not somebody who kind of just casually participated in palleting but people who were very well versed in how to perform a vousalva maneuver you know we're aware of how uncomfortable it can be how long to hold it how to generate those really big expiratory pressures why we wanted them to have a regular menstrual cycle we basically just said it just needs to be regular enough that so you can predict when you're going to be in your follicular phase to come in and be tested because the reflex behavior in that particular part of the menstrual cycle is the closest to how male reflexes behave so we just wanted to use that to make sure there wasn't any deviation that we weren't controlling for because one of our questions was around if the cardiovascular changes were dependent on sex or not okay so how many power lifters and how many so we had eight palleters i think from every but eight palleters and six people in the control room okay so now we want to know they came to your lab and what did you ask them to do yeah okay so in the lab basically what the participants needed to do was come in for a familiarization session because when you run an experimental protocol especially when you're using people who are sedentary and naive to a very very specific pattern of breathing sometimes that can bring with it a lot of anxiety for people you know if you're not somebody who is a lifter time to think about breathing against resistance does actually take some training in and of itself so we didn't want the experimental results to be muddied by the skill deficit so basically people agreed to be part of this study and came in for the familiarization session where they were hooked up to all of our equipment and then basically taught how to do about salamu anuma on this funny breathing apparatus that we made to simulate the resistance that your abdomen would normally generate but we built a little mouthpiece with a piece of tubing and it was resisted to about 99 percent again so we were controlling every single control of all that we could and basically that just went the familiarization went for as long as it took them to develop that skill set most people didn't take any more than about 30 or 45 minutes and then they were just run through the experimental procedure knowing what to expect when they were going to come in for their actual testing session so when they returned for testing basically they just sat really really quietly in the lab it was pretty dark because we were doing ultrasound while we just collected all of their baseline data so as i said they were on 12 EDG things are arterial blood pressure and also echocardiographic images so we were doing chest heart ultrasound through their chest floor at the same time so once we had collected enough of their resting data they were on a little it's like a car seat built into a swing i'll see if i can find a picture for you but my supervisors have built it for the lab and basically they would sit in there amazing yeah so yeah they would basically sit kind of semi-reclined tilted to the left because we were collecting ultrasound so tilting them to the left meant that their anatomic restructures could move a little bit further towards the chest wall and it made getting the image easier and basically they in real time were shown their little target screen so i'd marked out the 30% and the 50% of their maximum expiratory pressures and basically they were asked to do a 15-second valve salvin maneuver at 30% then they would get a minute recovery then another one at 30 minute recovery then one at 50% recovery and another one at 50% again so yeah and for the sake of you know reliability and retesting then all of the participants were tested twice and anybody that kind of had any disruptions in their data those particular testing sessions were really done so not everybody needed to be retested three times but you know some people came in and it was just like a really hot day so they were sweaty so the electrodes wouldn't stick or they became a bit evasive and bagel so doing the breathing maneuver made them a bit dizzy so we needed to kind of account for that that stuff as well so a few of them had um yeah like retests or physiological glitches I say so our study kind of looked at two the two main questions were around training and intensity so obviously training was the power of this versus the sentry group in the pilot study what we found was that heart rate is a positive function increase effort and increased respiratory pressure which you know in the pilot study we were limited so we only looked at heart rate but we you can kind of draw a parallel between heart rate and blood pressure so heart rate is behaving in a certain way you kind of get an idea of what blood pressure is going to do so when we had the power lift design we were looking at their baseline measures so as I said statistically their baseline respiratory pressures were significantly higher than the sedentary group now when we looked at all of the data what we found was that there was significant differences in heart rate, cystolic blood pressure and diastolic blood pressure responses in the power of this versus the sedentary group now overall the cardiovascular passion was the same so kind of in that diagram that I was showing in the beginning the nature of the behavior was the same but they started from a lower low and went to a higher high in all of their cardiovascular variables what we basically found in terms of the power lifting difference is that it's basically the same as what other people have found in other contexts of isometric exercise when you're looking at cardiovascular parameters so you know there's a couple of landmark studies in exercise science that were done back in the 80s looking at group isometric contractions and hydrosympisometric contractions and the cardiovascular pattern that occurs in those kind of contexts is exactly the same as what we see in balsalvo livers so even though it's not a skeletal muscle task kind of per se the fact that it's a isometric muscular contraction in a different kind of way the cardiovascular system responds exactly the same we also didn't want to discount the contribution that skill had in that that outcome as well so you know along with the background in how they breathe generally have more you know trunk muscle mass and stronger respiratory muscles but in-spiritory and expiratory that was all contributing to this significant difference in their ability to generate respiratory pressure and then have a more kind of attenuated response in their cardiovascular system so some of what we found as well was like we could we were starting to see the a tendency for difference in one of our variables so in systolecular pressure in phase three I think it was we could see that there was some variation but then the sample size wasn't quite big enough to give us a definitive answer you know obviously our end total was only 14 we had the joy of having our lab experiment interrupted by covid so 14 was the number of people that we had recruited at the time the university said please stop coming like the university is closed so that was the data that we were kind of like left with to interpret so what was interesting about that though was because of that that was occurring in phase three so we know that the valsalaminobrist stopped but the cardiovascular system is still going and what was interesting about that is that that particular phase has a lot to do with how compliant your vessels are so resistance trained athletes as a general will have a bit more arterial stiffness than endurance athletes and even people who are a bit more sedentary this doesn't appear to be a problem thus far there's a stack of research on resistance trained athletes particularly in terms of vessel disease or like vascular behavior so it was really kind of difficult to draw some guidance from other researchers who'd potentially use you know bigger sample groups or had more specific expertise in vascular behavior but it was super interesting to find that you know there is some kind of weird systolic blood pressure behavior happening in that phase in a cohort that has historically known to have stiff vessels so that's just another another question so if anybody knows anything about um strength athlete vascular behavior i'd be really curious to hear everything so can we ask you to speculate though what what could be going on you think so i think that perhaps it's got something to do with like the vascular smooth muscle and its ability to stretch and relax but perhaps it's got to do with almost the relief felt on the vessel for one of a better word like you generated all this into thoracic pressure especially in lifters where it's significant amount of pressure on the on the vasculature in the chest throughout the vousalva so compressed to a greater degree than in the sedentary cohort and then the fact that you're just then releasing all of that pressure to me thinks maybe it has something to do with the response time in that very short window of phase three like those few cardiac cycles yeah like it's it's really curious like i know it wasn't a significant finding because of the sample size but i just found that really really interesting one of the more interesting things from the lifters perspective that's still like obviously a glaring hole in our research what was the the trend specifically was it longer was it more of it how the vessels relaxed more oh so the the magnitude of the systolic blood pressure response in phase three in the power lifters was generally quite a bit greater but kind of variable within the power of the group themselves so as i was saying it wasn't statistically significant to the point where we could report it you know as a as a significant finding but the fact that the phase three behavior wasn't quite the same as what we had seen in phase one and phase two and then that that interest was compounded by the fact that that's the point where the mechanical stimulus has been removed so the the cardiovascular system is going on in kind of this reflexive manner that's kind of what i was saying and i'm not sure yet i mean we we know that resistance training is is great for our skeletal muscle it's good for our bone mineral density um it's good for our sanity so i think something that you know a lot of kind of lifters get caught up in is really like tying their identity really strongly to the fact that i'm a lifter you know i'm not super familiar with the weightlifting culture but it's certainly the case in like powerlifting it's almost like a meme to be like it to be a fat stiff power lifter right so i mean my kind of point would be well we know to a certain extent that strength athletes do have stiffer vessels that's still an area that needs like a lot more work done but broadly that's what a lot of the literature currently says so if it was me i'd think well if i'm already got if i've already got slightly stiffer arteries then really it's in my best interest and my health to do more work on my cardiovascular fitness and not be so strongly tied to the fact that well i'm a powerlifter and i don't do cardio so i mean people get caught up in the interference effect and thinking well if i do you know 30 minutes of cardio a day like it's going to impact negatively on my lifting and i think that really unless you're going to you know you're in a peak for nationals only going to the olympics like really we don't need to worry about it we're all just here to have a good time get a bit stronger so i think doing a bit of cardio is probably not going to hurt your gains i mean if anything it would help because the fitter you are the harder you can train for a longer amount of time stay healthy enough to stay in the sport for long enough to get good because as we all know like strength sports are truly a delayed gratification process um you got to play the long game with them you know hashtag lifetime intermediate you know we're not always all going to be like lifters all the time like i really liked your own heights with my friends i would like to live past 80 being able to achieve those things and being able to live like a normal healthy life like a normal young active person is probably probably more important to me than being really stuck on this idea of will i'm a pallet or so i'm not going to do any cardio but from a purely cardiovascular like physiological point of view i would say given that we don't know enough about this arterial stiffness type thing like just keep your vessels in as good health as well as you possibly can so one more question related to that if if the athlete let's say will reverse the stiffness of arteries will it affect his ability to generate pressures during vaseva maneuver so i think what really what we found was that the cardiovascular adaptations that were occurring in the power difference that we studied weren't necessarily a training adaptation per se it was more a combination of they were already skilled at this particular task we were asking them to do they already held a lot of trunk muscle mass which then we know is correlated with respiratory muscle strength and the ability to generally take big breaths and generate a large amount of respiratory pressure so i think that you know if people were just being generally healthful doing their kind of like doing their cardio keeping reasonably fit and well i don't see how that would negatively impact your ability to continue to generate high intraothoracic pressures in order to you know splint to do a big lift i mean if anything if you had good cardiovascular fitness i would speculate that you'd just be able to take bigger breaths and hold them for a longer amount of time and then thus generating more intraothoracic pressure if that answers your question yes yes because i think the lift like if you are a lifter you will wonder oh okay i'm like it's good for my health but how it impacts my lifting so i think i had to ask this question yeah yeah i have one one more question in in weightlifting it it happens from time to time that the lifter is diving under the bar pushing it up so imagine front squat and then they black out that doesn't happen in powerlifting yeah definitely um people definitely blackout in powerlifting um people definitely do pass out when you know you have that big intraothoracic pressure and it's like quite stimulating for your vagal nerve and so sometimes when people have a bit of vagal sensitivity you know it'll just take a very small amount of difference even if they train all the time if they get particularly hyped or you know their position was slightly different something's just something's just a little bit more off than it normally would be um yeah people can blackout all the time it happened to one of my participants in the lab while they were lying down and it's just you know you're having these huge changes in your blood pressure um and then some people just aren't as adapted compensating with the heart rate sometimes okay is there anything the athlete or the coach can do when it happens not really to prevent but when it happens do you have any advice how to get the athlete to be left right like in weight lifting they have a chance if it's not the last lift they can go back within possibly two minutes so they can redo the lift or even go up with the weight what can the athlete and the coach do you think to improve the chances of succeeding the second done i would say like basically what you want to do is obviously expedite their recovery from the the dip in the blood pressure because presumably that's the part that makes them faint is that they've held their breath for so long and because that vessel compression they've impacted their venous return to a point where their brain isn't being confused and they get their blackout so i would say probably put them in a position to um like facilitate as much being as return as possible which is just to like lie them down on the ground legs in the air get as much blood volume into that central um central circulation as you can you can try and supplement with like drinking like drinking water or Gatorade or something like it's really hard to know if that's going to be impactful enough in the amount of time that you have available to you in a competition but even if this happened and they weren't going to go back out the best way for them to get more more volume is to use gravity to shun it centrally for you and then supplement it with external input so drinking more volume essentially i can't think of anything that would be timely enough to get them back on the platform personally yeah so what we're trying to do basically is is pulled or shift the blood from the legs back to the thoracic and abdominal thoracic and head yeah basically because you know when you're holding your breath and the vessel is compressed then you're not going to get the benefit of that venous return through the compressed vessel so you're just trying to reverse that part of it awesome thank you and the final advice you would have for the lifters i would definitely say like please do your cardio you know just general health i know you like love tying your identity to being a powerlifter but it's cooler to live to old age rather than being a fat powerlifter and i would probably say just like out of the blue like if you happen to see people who are recruiting for powerlifting lifting research or research more broadly really like give it a go because it's quite good fun to actually contribute something positive to our like our sports are so small and i think that obviously contributes to the really gross lack of scientific like robust scientific research in you know weightlifting and powerlifting so if you yeah if you happen to see the opportunity to volunteer for a study like please please please do it your participation is like absolute gold and it makes us you know one step better in doing evidence-based work for people who share the same passion as you thank you for that yeah that's such a good message what comes next for you will you do more research in powerlifting i will do more research i'm actually starting my PhD next week so thank you i'm super excited it's been a long time coming so i submitted my masters in the middle of 2021 and then because of covid and everything and there was you know some funding issues so i've been waiting 18 months to get started on my PhD so that's really exciting it's not necessarily in the powerlifting space anymore so my masters with a bit of a passion project for me because it was my first step into research so i really wanted to do something that i already knew i was interested in but my PhD will be looking at still exercise testing but in a clinical population so looking at heart failure patients and then maybe when i come out the other side of that i can come back to to more like healthy part type work please do please that we'll be waiting for you but i'll still be around like i'm in the powerthing space like i referee at competitions and stuff so it's still very much a like a big lot of mine awesome your favorite color my favorite color is yellow i've got a crocodile she's yellow oh here she is hello so she's my favorite color all right noted so i will make an infographic from your study and it will be in yellow that's a promise awesome thank you and the last question where people can find you and follow you and your work yeah so i'm on twitter at the moment so i think my username there is like physiologists so the word physiologists and then the letter k and the number eight so like physiologists k or so on research gate you know i put my i put the paper up there so if people want to contact the before text more than happy to to distribute it i'm also on instagram where i talk like a little bit about my research for this mostly like science memes and cockatiels um but if people want to follow me on there it's cateau which is just kat0.potato and then two underscore thank you so much it was a pleasure i learned a lot i'm sure people who will be listening will be will be very interested to listen to our conversation thank you so much and see you next time thank you so much me invite Alex appreciate it You [BLANK_AUDIO]