Nerd Lab: Are All High-Intensity Intervals Created Equal?

Physiologist Rob Pickels nerds out with Trevor Connor on four recent studies that span a wide range of topics, from the benefits of percussive massagers for strength work to the impact of pregnancy on elite runners. Tune in to find out more.

high intensity runner in the mountains

In this week’s show, exercise physiologist Rob Pickels and Coach Trevor Connor pick some interesting new studies and discuss what they mean. The four studies include a comparison of six weeks of different high-intensity interval sessions, insights into the benefits of percussive massage on strength work, what are exerkines, and the impact of pregnancy on elite runners. Though the findings of these studies may not always directly apply to your weekly training plan, we boil down the most important messages and help explain what you can take from this research to be a healthier and stronger athlete.  

Comparing Six Weeks of Different High-Intensity Interval Sessions

We have frequently discussed on the show whether all high-intensity interval protocols are the same or if they produce different results. This interesting study titled Effects of 6 Weeks of Different High-Intensity Interval and Moderate Continuous Training on Aerobic and Anaerobic Performance explores this question from a team sports perspective.  

The study found that there were differences between short very high-intensity intervals and longer VO2max style intervals. However, that wasn’t the only interesting takeaway from this packed study. Listen in to find out more.

Does Percussive Massage Help Strength Work?

Imagine you’re in the gym and you notice an athlete in the corner stopping between sets to pull out a percussive massager to work their muscles before doing their next set. You might think they’re a little weird, but the question is: Are they on to something?  A recent study, Acute Effects of a Percussive Massage Treatment on Movement Velocity During Resistance Training, addresses that question. If you can handle people looking at you a little funny, this research might motivate you to change your own routine.  

What Are Exerkines and Why Are They Important?

The term exerkines was only coined in 2016, but the idea has become so important that a large consortium of scientists are scheduled to meet this year and will be making it the focus of their meeting. Many of those participants just released the review,  Exerkines in Health, Resilience, and Disease. The term simply refers to the signaling molecules in our body that are released due to exercise and have an impact on our health. This impact is proving to be highly varied and important, as it’s affecting everything from diabetes to heart disease, bone health and gut functioning. As athletes, exerkines may be one of the most important things in your body that you’ve never heard of. 

What is the Impact of Pregnancy on High-Level Runners?

Rob surprises the team with a study that was published last month, Impact of Pregnancy in 42 Elite to World-Class Runners on Training and Performance. This study explores not only the impact while female athletes are pregnant, but how quickly these high-level athletes can return to their previous level, and any potential long-term effects of pregnancy. 


Cavar, M., Marsic, T., Corluka, M., Culjak, Z., Zovko, I. C., Müller, A., … Hofmann, P. (2019). Effects of 6 Weeks of Different High-Intensity Interval and Moderate Continuous Training on Aerobic and Anaerobic Performance. Journal of Strength and Conditioning Research, 33(1), 44–56. Retrieved from 

Chow, L. S., Gerszten, R. E., Taylor, J. M., Pedersen, B. K., Praag, H. van, Trappe, S., … Snyder, M. P. (2022). Exerkines in health, resilience and disease. Nature Reviews Endocrinology, 18(5), 273–289. Retrieved from 

Darroch, F., Schneeberg, A., Brodie, R., Ferraro, Z. M., Wykes, D., Hira, S., … Stellingwerff, T. (2022). Impact of Pregnancy in 42 Elite to World-class Runners on Training and Performance Outcomes. Medicine & Science in Sports & Exercise, Publish Ahead of Print. Retrieved from 

García-Sillero, M., Jurado-Castro, J. M., Benítez-Porres, J., & Vargas-Molina, S. (2021). Acute Effects of a Percussive Massage Treatment on Movement Velocity during Resistance Training. International Journal of Environmental Research and Public Health, 18(15), 7726. Retrieved from 

Episode Transcript

Trevor Connor  00:05

Hello, and welcome to Fast Talk, your source for the science of endurance performance. I’m your host, Trevor Connor here with Rob Pickels, and Rob, it’s time for another Nerd Lab. Which means that half of our listeners probably just stopped this episode and moved on to the next podcast.

Rob Pickels  00:21

And the other half probably got their notebooks out and are writing everything down. There we go, which half do you like better?

Trevor Connor  00:27

Oh, boy. Are we picking favorites on the show now?

Rob Pickels  00:29

As long as they’re not Canadian.

Trevor Connor  00:31

Yeah, you haven’t done a Canada joke?

Rob Pickels  00:33

I haven’t, and actually one, one study that I might spring on you later, Trevor, I’ll give you a little teaser that you might not be prepared for this, is actually a Canadian study that Canada did something good. So, I might bring that to the table, if we got time.

Trevor Connor  00:49


Rob Pickels  00:52

If you’ve been listening to Fast Talk for a while, you know that we’re big supporters of Dr. Stephen Seiler and the polarized training method. We believe in polarized training, because the science supporting it is strong. So we’re pleased to announce the release of part two of our new guide to polarized training. Our polarized training pathway now offers five new stories that will guide you to creating your own, custom polarized training approach. Make this the year that you master polarized training and unlock your elite. Learn more at

Trevor Connor  01:30

Where do you want to start? So we got a few studies here. And they’re kind of all over the map, which is gonna make them really interesting. I don’t think we’re gonna get heavy on explaining all the methodology here. But really get into what you can take out of these studies. But we got one on strength training, we got one and intervals we’ve got one on, ready for the term, extra kins. Extra kins, and then you got something to spring on me, which I don’t even know what it is. I’m excited.

Rob Pickels  01:55

All right, Trevor. Let’s see, I think that if I remember correctly, you were a big fan of this study by caviar effects of six weeks of different high intensity interval and moderate continuous training on aerobic and anaerobic performance.

Trevor Connor  02:11

Yeah, I was interested this study. And there’s a lot to this study. So I don’t think we’re going to dive into everything. The Lisa, which was this was actually really focused more on soccer players, tennis players, athletes like that, who have a lot of change in motion. So they were trying to do intervals where you actually do a shuttle run, which is you run to a point, stop, run backwards, go to a point and just keep going back and forth, to see the effects of that change of movement. But what I found really interesting about the study was they were looking at high intensity intervals, and they did a traditional high intensity interval that’s a little longer, so about four minutes in length. And then they did a really short intensity intervals, less than 60 seconds, basically, for the intervals to see the impact. And we’ve had that conversation about, you know, high intensity intervals. Do they all basically get you to the same place? Or do they have different impacts? And we certainly had some very high level coaches come on the show and say 32nd, intervals, 22nd intervals, one minute intervals, they’re all basically the same. Pick what you find to be fun.

Rob Pickels  03:20

Yeah, you know, you bring up this study, and and one really interesting point for me was the fact that it was a team sports based study. And for me to look at how many acronyms I did not understand in this paper, oh, my God, no, it was like ma SSMVTMM something or other, I actually had to convert everything into into cycling terms. And so they’re longer their standard one, I equated very much to a vo two max effort, like we would sort of define that Right? Kind of about as hard as you can go for that four to six minute period. And then the other the shorter one, I equated that to basically being like a 90% sprint effort where you’re going really hard, maybe you could go a little bit harder. But essentially, for us in the cycling world, it was as if we were doing say 3030s Or maybe a Tabata where you can’t fool sprinting because the recovery is so short that, you know your performance would would decrease. So yeah, it was really interesting to see that they did these two different high intensity ones in this team sports world. But Trevor, they compared these two to continuous training, right, which I found really interesting because the continuous training they did was essentially 35 minutes of sub threshold running in a shuttle it 25 meters at a time back and forth, going in this zone two out of a three zone model intensity, and that was the same throughout the entire test period.

Trevor Connor  04:52

They admitted that they had issues with that they knew it really wasn’t long enough to get any sort of training effects and then just basically said If we were using students, students who were doing this between class, they really only had 35 minutes. So they admitted that was a weakness of the study. So I didn’t really the conclusions they drew about the high intensity versus moderate intensity training. And I went, Yeah, let’s, let’s not look at that. Because even they said, didn’t really test true continuous training.

Rob Pickels  05:24

I don’t know.

Trevor Connor  05:28

Drop this, gave me this look, well, he quietly reach for a coaster,

Rob Pickels  05:35

scarf and then loudly put the coaster on the table. So

Trevor Connor  05:39

the whole time not looking at what he’s doing just looking at me. It’s like, give me this look like, Did he notice me is he seen me do this right now my

Rob Pickels  05:48

dog does this all the time, just you see me trying to eat this out of the garbage.

Trevor Connor  05:55

What I think was really interesting about the study was taking these two protocols for training. So a six weeks of training, the as we said, the one that was what they called standard high intensity trainings about four minute intervals, again, doing a shutter on so it’s 25 meters turn changed directions, 25 meters, change directions, and then a much shorter, harder, you know, pretty close to max intensity interval, where you just did 15 reps. And they didn’t give time because they tried to make it individual. But it would have been under a minute for each person. And what they found was that the people doing the short intervals, saw much greater gains in the test that looked more at your anaerobic capacity.

Rob Pickels  06:43

And that test was a 300 yard shuttle run. And this is the most team sports thing in the world to do because one test was based in yards and the other was based in meters. But essentially that 300 yards shuttle run took people about 60 seconds to complete. So I’m like as a 40, meter hurdler. You know, I was like, I was like one lap around the track, you know, in in terms of effort, and that’s pretty hard.

Trevor Connor  07:09

Yep. And then the other group, which is that beep test, which as we said, it was kind of an approximation of a vo two max test. And it was interesting, the protocol behind that. But you found the group that did the longer intervals saw much greater gains in the beep test results. So the basically, they saw more aerobic gains that people do in the short, really high intensity intervals, saw greater gains in the on the anaerobic side.

Rob Pickels  07:37

Yeah. So to put that into perspective, on the beep test, which is the A robic approximation, the approximation for vo two Max, that short training group went from 95 to 103 shuttles. And the longer group that did, the longer the continuous the four minute efforts, they went from 96 to 108. So kind of five more shuttles than the other high intensity group. And to put that into perspective, that continuous control group we had mentioned, they went from 95 to about 95 shuttle. So really no change there. Both of these groups are doing 10 additional shuttle repetitions with the high intensity training.

Trevor Connor  08:16

Yep. The other thing I found interesting out of this is when you look at the people doing the long interval work, and the impact on that anaerobic side, so the anaerobic test, they did see improvements, just not as much improvement, but they saw fairly consistent improvement. On the other side, their group doing the very short, the short, very high intensity intervals. When you looked at their improvement on the aerobic test, the beep test, it was quite variable, about half saw improvement, a whole bunch didn’t see improvement, and two actually performed worse.

Rob Pickels  08:52

And I love research that does this, because they have graphs that show pre posts for every single subject. And this is a really important aspect of research that we don’t always talk about. Usually we just talk about group means and one group did better than the other group, therefore, it was a worthwhile treatment. But if 50% of that group did better, and 50% didn’t do better at all, it wasn’t worthwhile for everyone. So it was interesting to look at that. And yeah, you’re right on that beep test the longer group, universally, I’m looking at it right now. There was basically two people in that group that didn’t change much and everyone else improved quite a bit. Yep.

Trevor Connor  09:33

So to be this is actually some confirmation of things I’ve heard some really good coaches talk about so I saw something was similar with Dean Gulledge. I’ve seen this with Neil Henderson. Where local can do my bad where I opt in with athletes just immediately move into those really high intensity two bodice type intervals short, super high intensity and I go well, it’s going to improve both your aerobic side and your anaerobic side. Well, as we’re seeing here, that’s true and about half of people, but the other half, maybe not so much, you’re just gonna get that anaerobic capacity improvement. So I have seen coaches that as they’re moving closer into the season, they’ll first do that more traditional, or what they’re calling the standard high intensity here, to really hit that aerobic side, and then move into a few weeks of the super high intensity to hit that anaerobic side. And what I’m seeing here is a justification for that, because certainly everybody doing the standard intervals, those four minute intervals, saw improvements on the aerobic side. And everybody saw improvements on the anaerobic side with the short intensity. So most consistent gains is going to be do the aerobic, then do the super high intensity. Yeah, it’s interesting.

Rob Pickels  10:47

For me, I’m just thinking about this personally, I typically actually start with the shorter, shorter recovery intervals, because I find them a little bit easier. So when I’m working up towards, you know, a higher continuous consumption of vO to max with my workouts and trying to push that aerobic capacity. Yeah, it is a little bit easier for me to do 3030s and 2010s. And that’s almost like the half step to get me to these four to eight minute intervals, which for somebody who is a natural sprinters are pretty tough, and no fun to tell you the truth, in my opinion. Well, I’ve

Trevor Connor  11:27

certainly seen that with even a lot of coaches who liked the more traditional approach to training that, in that very early season, they’re gonna give their athletes some of that super high intensity work. And the arguments I’ve heard for that are, this is not the scientific way to put it

Rob Pickels  11:43

to say you haven’t heard a good argument or no, it’s just more it kind

Trevor Connor  11:47

of opens you up, it gives you that ability to tolerate the pain a little more. So then when you move into threshold intervals or something a little more aerobic, you can do them a little harder, just because that anaerobic system has been turned around here, you still little pain.

Rob Pickels  12:03

Yeah, I do think that that is the undermining of a lot of the longer view to intervals. Yeah. And we had a big discussion about this whole concept with with Hunter Allen a few weeks back if people want to listen to that episode, but I know for me motivation, the place I am mentally, my ability to handle that suffering really affects the quality of those intervals that I’m able to do. And there’s just something in my mind that says, Well, if I just go for 30 seconds, or 20 seconds, or whatever it is, and then I take a break. Sometimes it’s hard to start the next interval, but I can pretty much always finish an interval once I get going. Okay, so,

Trevor Connor  12:39

Rob, anything else that we want out of the study?

Rob Pickels  12:42

Yeah, you know, I think it’s interesting. I did look at a couple other pieces of research with this. There was a meta analysis in 2013. From just and I looked at some of Izumi Tabata is work on this, just to see if it was consistent the results that we have here and in some regard, it is the sprint interval training in this meta analysis, it increased a robic capacity and healthy untrained individuals. And in my opinion, that’s a lot of who these people were they were students who had maybe had a soccer background, but we’re not talking endurance athletes here, not high level athletes. Exactly. And then also on the Izumi Tabata side of things. Yeah, maybe similar there, they actually saw a little bit of more improvement in vo two Max. But again, I think that that’s maybe because of the the Tabata protocol is a shorter work with a very short rest interval, which really limits the workload that people are able to do that out. So maybe kind of the the protocol that they’re talking about here to a little bit more of an extreme and actually pulling that workload down. Maybe targeting more of that vo two level.

Trevor Connor  13:46

Yeah, well, going back to what you said at the very beginning, they even say in this study that the results they saw, particularly on that aerobic side were less than what you’ve seen in other studies, because other studies were continuous. Yep. Meaning if you did that four minute interval, you’re on a trainer or you’re running and you’re just kind of going in a straight line. Being consistent. When you’re doing the Shuttle Run. You’re constantly have to stop and then go again, and then stop and go again.

Rob Pickels  14:11

I will give props to these researchers real quick before we move on because I had my assumption was that they had these continuous people. In my opinion, they were just setting the continuous people up for failure the whole time. And I was like, I bet you they had those continuous people just do continuous runs. And they didn’t those poor continuous people had to do as Trevor said earlier, shuttle runs back and forth with his 13 us. Good Lord. That’s an interval workout. I

Trevor Connor  14:37

don’t want to do I think I did that in high school football. Not perfect, but I’ve tried to block it out of my memory.

Rob Pickels  14:43

Well in high school football to Trevor, did you do any weightlifting? Yes, I did. You did? Did you know that? If you used percussive massage treatment on your pec muscles. When you were weightlifting, it might have improved your performance.

Trevor Connor  14:59

Good attempt To throw to the next study,

Rob Pickels  15:01

I think that was a great throw. So let’s talk about

Trevor Connor  15:03

it before we move on, just just just because you brought it up. Here’s something you probably didn’t know. I was a lineman in Canada in high school football in Canada. Yeah, it was in Canada. That’s where I went to high school. Yeah. We actually didn’t call

Rob Pickels  15:19

it high school. But that’s a whole different discussion, like secondary school or something.

Trevor Connor  15:23

I went to a college this.

Rob Pickels  15:26

Wow. Trevor graduated college at 18. You heard it here first.

Trevor Connor  15:31

No, I started grade five in a college. Perfect. So but yes, I was alignment was also 220 pounds. But that’s a whole different story. Wow.

Rob Pickels  15:39

Man, you might have been a real lineman at that weight. I’ll let the listeners determine what they think of that.

Trevor Connor  15:45

People bounced off me. It was fun. Now they would roll over me.

Rob Pickels  15:49

And yeah, exactly. And now you bounce off them. Yeah. And by

Trevor Connor  15:52

the way, that’s how I’m gonna die. I still think of myself as 220 pounds. One these days, I’m gonna go into a bar and pick a fight with a guy this size. That wasn’t sciency at all. What’s our next study?

Rob Pickels  16:02

acute effects of percussive massage treatment on movement velocity during resistance training, this came out when did this come out? 2021. So relatively new, by Garcia Solero. And I think this was out of Spain.

Trevor Connor  16:17

I know you’re really excited about this one. Because you love your percussive massage.

Rob Pickels  16:21

I do. And this episode is not sponsored by anyone. But I have pretty much all the percussive massage therapy devices out there. I love them all for their unique qualities. I love them all the same, just like my kids.

Trevor Connor  16:34

There you go. But so which is your true favorite? We won’t tell it.

Rob Pickels  16:37

Um, I’m into the theragun Right now I am. But I do have the hypervolt as well. My wife uses the hypervolt more than I do. Okay, now, I’ve got two other Thera guns. Nice. So Trevor, this study, I’m going to name it because it’s in this study, they use the Thera gun device. But I do want to say that it was not sponsored, they received no outside funding, and they didn’t, they didn’t announce any conflicts of interest, which I like to see. Not that I don’t trust research that’s sponsored by companies, because I think that some really good research comes out. But at the same time, something in the back of your mind has a hard time trusting it, whether or not it should. So anyway, I thought that was awesome to see with this.

Trevor Connor  17:16

Yeah. And they had to pick one of the devices, even if they weren’t funded. So

Rob Pickels  17:20

So let’s give some background info on this. I got to scroll through my notes to actually find where they are. So yeah, they were looking at evaluating percussive massage treatment for improvement during weightlifting. And something I found really unique in this is that they were using movement velocity. So they that was actually probably my favorite part of the study, you know, right. And this really showed me we know a lot about endurance training and science. And this was, in some regard a new concept to me in some regard not. And so I’ll expand on that in a second movement velocity. For the purpose of this study, they were essentially timing how long it took for the athletes to complete a benchpress. And the single bench press Correct? Yes, one single repetition. With the thinking being as you lift heavier and heavier, your movement slows down, right, so a one rep max, you’re moving slower than if you lift five pounds. But also throughout the course of a training session, as you do one rep, two reps, three reps, four reps, so on and so forth. As you fatigue, your movement slows down as well. And so they were saying, independent research of this has shown that you can be specific about adaptations, if you stay within a range of movement velocity. And if you stop the exercise, when your movement velocity slows down beyond a certain point, so instead of doing three sets of 12 repetitions, it would be three sets of repetitions until you slowed down too much. Yeah, that

Trevor Connor  18:56

was actually the biggest thing I took out of it, which I said that might be the better way to promote adaptations. Because for one person, 10 reps might be right for another person. 15 reps might be right. So instead of just giving a random number, go until you can’t keep the speed anymore. And I

Rob Pickels  19:13

think it was a really great and I don’t want to say attempt, I think it was a great execution of of being able to put metrics to what’s happening here. And we have metrics that surround us in the cycling in the running world, but not so much in weightlifting. So that was very unique to me. Yeah.

Trevor Connor  19:30

So what I loved about this study is it actually gave some really good advice. I found some great results. But if you follow everything in here, you are going to be that guy in the gym that everybody’s going to stare at and give a wide berth because you’ve could not even that is going to be weird. Basically what they had these people do is benchpress until they couldn’t maintain the velocity anymore. They did four sets, and in between each set, they would get on the ground. take out their theragun, use the theragun on their chest, 15 seconds per side, I believe, yep, and then do their next set. And the idea was to see how many reps they could do in each of the four sets with the theragun. And the results were the group that did not use the theragun, they saw the number of reps, they were doing decline from set to set the set, the theragun group in all four sets did the same number. So they were able to resist that fatigue with the theragun.

Rob Pickels  20:31

Yeah, and that fatigue resistance is really important here. So the sets were at 70% of their one rep max, just to give people an idea. And we’re talking a range of 11.4 to 10.3 reps on the percussion gun. And then in the control group, they went from about 11.3, down to eight reps at the end, so a lot of fatigue there. But the researchers note in this, that the percussive therapy has not been shown to improve jump height, it hasn’t been shown to improve strength necessarily. Nobody in this study was quote unquote, stronger or lift more not that they were looking for that. But what it did do was it perhaps decreased the fatigue that people were experiencing, allowing them to do more repetitions, which probably hopefully leads to them getting stronger, better adaptation.

Rob Pickels  21:23

Exactly bigger load.

Trevor Connor  21:25

So I admit, I found this really fascinating. And when I get back into the weight room next year, I’m actually going to try some of this. So

Rob Pickels  21:33

you can do this tomorrow. If I go into the weight room? Well, you know, yes, I don’t want to be 220 pounds now, do you?

Trevor Connor  21:40

Yeah, that wasn’t I’ll do the waiver. Let’s face Max,

Rob Pickels  21:45

I have a latte in my mouth that almost exited quickly. But

Trevor Connor  21:48

no, I want to try this. Fortunately, I work out my basement. So not going to get weird looks. But I think when I hit that heavy strength phase, my hypertrophy phase as well, I’ll get to try this go till decline in velocity. So I think that’s really interesting, and might try a little theragun. In between my sets on the more important lifts. Yeah, Trevor, I

Rob Pickels  22:09

actually think that we should look a little bit deeper into this movement velocity side of things, because they’re, they’re talking millisecond differences. And I wonder if we’re able to perceive or quantify that without some sort of external equipment. So I want to know more about what equipment they were using. And frankly, I just didn’t have time to dive into the supporting research that really outlined the movement velocity side of things.

Trevor Connor  22:34

Yeah, that would actually be a really interesting thing to dive into. Actually, what I found really interesting about this study, and the previous study is, again, as you point out, as cyclists, even runners who are on a treadmill, we have this advantage that we have a lot of metrics, we can control pace, like if you do a vo two max test on a treadmill or a bike or domitor, you can control the power or the pace. And in a vo two max test, you want to keep ramping it up. So when I read that previous study, and they said, Well, we use a beep test where you’re going back and forth between these cones and you slowly increase your pace and like how do they figure out the pace? How do they keep up with the pace and literally what they were doing was they had a table of each time you go between the cones, here’s how quickly it has to take you and they they had a device that would be but the athletes of when they had the hit the next cone. So it was up to the athlete to find the pace. And basically they failed at the VO two max test when they couldn’t get to the next cone right in time. Yep. But still, the athlete has to control the pace. And it’s the same thing here. You got somebody literally sitting there trying to time their their lifts and the pace. It’s much harder in a lot of these other sports to find these metrics that are so easy in cycling or running.

Rob Pickels  23:53

It is and so I’d love to take this to the place that I feel safe. And that’s cycling. Right. Trevor? What is the application in your mind? How can a cyclist use this outside of the weight room? Is there any application there?

Trevor Connor  24:05

Do intervals of about theragun? In your jersey pocket? Yeah,

Rob Pickels  24:09

that’s kind of kind of what I’m thinking you go in there?

Trevor Connor  24:12

Is that what you’re thinking to do it

Rob Pickels  24:13

I am kind of going there. Is there a way Okay, so So backup backup come come on a journey with me. Everybody close your eyes. If we think about what’s what are watts, watts are the force multiplied by the speed that you’re applying that force right I mean, Bryce very simple equation for watts. And if we look through, and I did, I did a little bit of supporting research for this, you know, Rutelli in 1996. And we can link to this paper as well. Maximum Power degradation in a cyclist doing short intervals is due to both a drop in force and a drop in speed. So if we know that whacking yourself with a percussive massage therapy device helps maintain the speed is something like this applicable for between reps or Between sprint interval training which we were talking about in the previous study and is becoming more and more popular. If you’re sitting on the trainer, you do your 22nd Tabata or whatever you know maybe a Tabata is not hard enough. But do you massage your quads or your butt or your calves whenever you want whatever slowing you down? Do you massage them between these all out efforts? Maintain that sprint power again and again and again. And can we turn somebody like you into a sprinter? Oh, that’s

Trevor Connor  25:29

a big asked her name had to be more than the theragun. To do that.

Rob Pickels  25:34

You need the weightlifting that also goes along with this perhaps a

Trevor Connor  25:38

weightlifting certainly going to help my answer to you is we often get accused of being nerds. Boy, do we deserve that if we are going to be sitting there out on the trail, doing sprints and then fold over to the side of the road and hitting ourselves at the theragun.

Rob Pickels  25:52

Alright, let’s solve this problem. I’m a product guy. Let’s solve this problem. Somebody out there invent. I want a pair of bib shorts that have percussive massager built into Trevor almost spit out his T. We’ve done it to each other at this point. I want bib shorts that have this built in and immediately upon stopping an interval, I want them to detect that maybe through EMG. That’d be a great, great way to do it. And then start to massage between intervals. And then as soon as you go again, it turns off. It’s a million dollar idea.

Trevor Connor  26:23

So some poor commuter on the trail is going to pass a cyclist passing cycle. electrodes attached to their legs and their shorts are doing strange movements that they can’t explain or

Rob Pickels  26:35

there’s like a dance going on to Putin, Putin Putin. That’d be awesome. Let’s do it.

Trevor Connor  26:41

That is not the conclusion I draw.

Rob Pickels  26:44

No, let’s, let’s shut down fast talk and put everything into this idea.

Trevor Connor  26:47

Okay, yeah, that is not a million dollar idea. But let’s try. So no, I mean, I get out of this exactly what they were going for us this in the weight room. Yeah, I mean, if you’re in your basement on a trainer, and you want to try this in between some short high intensity intervals, there might be something to that. I certainly think a track rider who’s doing a hard sprint and then getting down on the grass and resting, they should have that theragun there or whatever their devices and hit their legs before they do their next sprint.

Rob Pickels  27:18

Yeah, maybe track and field athletes runners as well. This might be a little bit more applicable in between intervals a little bit easier there when you’re doing it on the track instead of pulling it out of your jersey pocket on the on the old bike path.

Ryan Kohler  27:37

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Trevor Connor  28:07

So what’s the next one?

Rob Pickels  28:09

The next one is it’s a big one. I don’t even want to list the 22 different authors that are on this. But the title is nice and short. Lucia

Trevor Connor  28:17

was big name and Exercise Physiology, and he is one of the authors.

Rob Pickels  28:21

So this is extra kins in Health Resilience and disease. And Trevor, this is this is your baby. I think, Trevor, I think you might need to explain this to me a little bit. I think I missed the point. So I

Trevor Connor  28:34

love the fact that I pick this one rubs like why? Read it. The first thing you said to me after you read it was why?

Rob Pickels  28:44

I tried to I tried to talk to her out of doing this research. But I like I say sometimes and this is what’s important, right? Sometimes research just doesn’t speak to you and it speaks to somebody else. So it doesn’t mean it’s not valid. And what I want to do, Trevor is I want to hear your interpretation from this because I do truly think that I missed the point of this research paper

Trevor Connor  29:04

well, so good. I have an immunology background. So I saw this one I was really excited about it. I just read through the whole thing and they’re bringing up all these cytokines that I’ve spent years studying and their impact and just went out that’s cool. So to me this was a really fun study I will say if you have that immunology background, if you know what the various cytokines are and chemokine czar This is a great study to read your review it’s actually not a study you’re gonna find this really interesting if you don’t love terms like aisle six and dip a nektan and Apple in and all those sorts of terms and maybe move on to something else read some more percussive

Rob Pickels  29:48

Yeah, shorts. Yeah, this is this is this is boring. Oh, poor Wheaton. Yeah.

Trevor Connor  29:55

I was riveted by this. What but we’re not going to go into all these different molecules. I’m not going to bore you with this. But the idea and why I think this is really interesting for anybody to listen, this is not a performance study, this is not, you’re going to get faster or better. This is much more a health study. And this term extra Kim is basically referring to signaling molecules that are upregulated, or impacted by exercise. So it’s not these are molecules that only exist, are created when we exercise. They’re used for other things. So for example, the first one that really sparked this research, they discover that exercise upregulated, something called Il six, that’s a cytokine. Il six is a very important cytokine in our immune system. And it’s very interesting because it has both inflammatory and anti inflammatory effects. And they showed that exercise when you exercise hard, your muscles will upregulate il six, so they went, Wow, exercise, using your muscles seems to have an impact on the immune system.

Rob Pickels  30:59

I’m just picturing a researcher in a lab going, Wow, look at that. Cool. And the problem sometimes is that, when you’re doing research on new things, you see the effect, you see the thing that changes, but it’s maybe another step or two removed to understand why that actually matters. So the big picture

Trevor Connor  31:19

of this is, I think, sometimes when we exercise, all we’re focused on is adaptations. So you go, Okay, I’m gonna go out and do some hard work. And that’s going to improve the mitochondria, my muscle cells, that’s going to make my muscles bigger, it’s going to improve my heart, and you don’t really think beyond there. Yeah. And what they are showing with these extra skins, and there’s a large list of them that are impacted by exercise, is they have huge impacts systemically throughout our body. And it’s just it was fascinating going through the list and seen both the number of molecules that are impacted by exercise and the effects that they have. So they went through cardiovascular health and showed that there are several these extra skins that can really help with the the hearts function, they went through the adipose tissue and showed that these extra skins can promote breakdown of fat and also actually promote something called brown adipose tissue. So short explanation of that, as we have white and brown white tissue, basically think of it as dead, it doesn’t do anything except store fat. brown adipose tissue is actually metabolically active, it burns calories. And there’s benefits to having brown adipose tissue. They looked at the liver and gut function, I actually found it really fascinating showing that some of these extra skins can change the gut microbiome in beneficial ways.

Rob Pickels  32:38

And so this is something to point out when we’re talking about this, we’re seeing an extra skin that is released from a totally different area, you’re working muscle is secreting these little molecules in these vesicles. And they’re floating throughout your body and they’re landing in your gut, and they’re causing changes elsewhere that are kind of unrelated,

Trevor Connor  32:56

not just the muscles that’s really slim. So they said in the early research of Aster cams, they really focused on extra guns that were released by muscles. But they’re finding that they’re further Mexicans that are actually released by other tissues released by the liver, or at least by the indoctrinate system that are promoted by exercise and have these benefits. Yeah, just to continue with the quickly with the the overall benefits and avoiding all the terms. They showed that big improvements in glucose homeostasis. So basically, if you are at risk of diabetes, exercise improves insulin sensitivity. So it can help reverse some of those effects. big impacts on the immune system. We’ve talked about this before. And it’s really interesting, you get this kind of duality, where moderate exercise seems to aid the immune system will really heavy exercise seems to blunt the immune system. Likewise, acute exercise is very inflammatory. But chronic exercise if you’re exercising regularly, every single day, seems to be more anti inflammatory. So when you are rested when you’re sitting on the couch, brings inflammation down, which is really good thing. And

Rob Pickels  34:04

I think that this is why I in some regard struggled with this research. Because I think in my mind with my schooling and my background, all of this information is known, right? We know that exercise improves insulin sensitivity, but I guess in the whole scheme of things that’s like the first step and the last step, and maybe what this research is doing is filling in that middle step of how is it doing that? These are the molecules that are doing that? Yeah, exactly

Trevor Connor  34:31

that we’ve known for a long time. exercise improves insulin sensitivity as exercise improves bone health exercise helps the heart and there’s no studies you know, you have a group that does exercise you have a control group that doesn’t you see these benefits, etc, etc. that research has been for a while these extra kins. I mean, this term was only coined to what 2016 Yeah, and it’s basically saying there are these group of molecules that produce this effect signaling molecules that produces Fact. And we’ve really never studied them as a group. So let’s create this group called extra kins. And look at the molecules, the signaling molecules that are impacted by exercise that are either upregulated or downregulated. And see the various effects I have see how they produce these results that we know we get from exercise, because understanding that is going to allow us to improve how we use exercise for health, and even bring up at the end when you have somebody who’s has mobility issues who might not be able to exercise, we might be able to use these extra cans to give them some of the benefits of exercise without them be able to exercise. Yeah, and

Rob Pickels  35:39

that’s if God do I hate to say this, my mind when I was reading to this went immediately to which one of these can we put in a pill? And which one of these will make me a faster cyclist? I’m not going to lie.

Trevor Connor  35:51

Yep, can put in a pill, your body’s probably not going to absorb it.

Rob Pickels  35:54

I think that this is interesting, though, right? Because Saito Max has lactate in it as an ingredient. Don’t get me. Trevor’s literally rubbing his face right now.

Trevor Connor  36:07

It was my favorite drink mix of all time was one that included lactic acid, because if you consume lactic acid, yeah, your body is going to improve its buffering so that when you exercise, the lactic acid isn’t going to impact you. So let’s let’s address all the various issues with that. For one thing, we are way off topic. Now. I could never pronounce this. But we have a type of gut bacteria, the lacto. Basilica, sir, whatever it is, like so I could never pronounce it, that our name so because they produce lactic acid. So there’s already a lot of lactic acid in your gut, you do not absorb it, you might convert it to a sugar molecule first and absorb it. But at no point is that lactic acid get into your blood. Lactic acid does not exist in the human body systemically that is a myth that we continue to seem to perpetuate. So there’s no tolerance to lactic acid needed.

Rob Pickels  37:04

All right, fine, grumpy Trevor, instead of putting these things into a capsule, what if I put them into a syringe? Well, that’s what you have to do. And don’t do that people don’t do that. Don’t. I liked

Trevor Connor  37:15

that they didn’t go down the path of, well, let’s start injecting all these things at ourselves and make those better for farmers brought up the fact that we basically the theme of this is there are huge benefits to exercise to our health. Yep, we’re looking at what produces those benefits to health. Yep. And if you have somebody who is not able to exercise, the argument here is they can’t be fully healthy. So in them, put in a syringing. And injecting it might give them some of the benefits and allow them to live a healthier life, which is

Rob Pickels  37:47

important. Yeah. And at the same time, I think that this is talking about the holistic side of things that exercises is up regulating, or at least affecting, gosh, I think they have over 50 named you know, and this is where, you know, we say, hey, health and nutrients from Whole Foods is significantly better than buying that pill off the shelf. If you’re magnesium deficient, sure, you can take a magnesium supplement, but you’re not getting the whole benefit of getting magnesium from green leafy vegetables or other things that are high in it. Is that right? I just pulled that out of him. That you’re What magazine? I pulled that out of my pantry. The magnesium. Yeah, green leafy vegetables, right? It wasn’t what I was thinking

Trevor Connor  38:28

we were gonna go yes, you have it. Right. Okay, perfect. Good source, magnesium, also good source of calcium. Yeah, there you go. So I think the other key message of this study is there are so many of these extra cans, these molecules that we know have health benefits in the body that are elevated or impacted in a positive way by exercise. This is really the evidence that you cannot be healthy, in my opinion, without having physical activity in your life. Your body is designed to have regular physical activity to keep it functioning correctly. Yeah, if

Rob Pickels  39:02

physical activity is affecting so many different things, then it must be integral to what’s going on.

Trevor Connor  39:09

So does that answer your question? Are you still like why?

Rob Pickels  39:11

No it does. I do I get the importance in the fact that this is filling in the middle. You know, and I think that in some regard, a lot of my background is more as a clinical individual that the middle doesn’t matter so much. I just need to know the what and the endpoint. But you being the immunology background, I can understand why a definitely spoke to you. I’m just two steps ahead of you, basically.

Trevor Connor  39:35

Yeah, there we go. Always. You always are. By other favorite part of the study. They brought in PGC one Alpha.

Rob Pickels  39:41

Oh my god, I saw that. I know. You know, I

Trevor Connor  39:44

was excited at that point.

Rob Pickels  39:45

I was excited too.

Trevor Connor  39:49

All right, Rob, you’re good at Spring one on me.

Rob Pickels  39:52

Yeah, Trevor. I thought this was really an interesting study, especially based off of what we had just talked about with Doc for Stacey Sims, that episode on coaching, the female athlete has done really well. We’ve gotten so much great feedback in it. And I was reviewing some research in general and I came across this, that’s actually I have a published ahead of print. This was accepted for publication on August 5 of this year. So it’s a month old. And its impact of pregnancy in 42, elite to world class runners on training and performance outcomes, which is just, frankly, kind of a novel research. You know, that’s been done, there’s certainly been some research into how women in general should perform exercise, because it has benefits across all sorts of different things. Gestational diabetes, decreases the risk of preeclampsia, all of these things. But if you look at the WH O, their guidelines, basically just say, hey, get 150 minutes, which is about two and a half hours of moderate intensity exercise a week. That’s it, just just go for that. And they have no guidance on what happens if you do more, is it safe to do more Is it beneficial to do more. And frankly, we know that a lot of women are probably doing more than that. Some are definitely doing less, but a lot of probably doing more. So this study, and I do want to say right at the get go. This was this was a retro analysis, it’s just an understanding of what these 42 women did. I don’t know that we can draw safety recommendations or anything out of this. I don’t even know that we can draw training information out of this. I’m not saying this is what’s best, it’s just a description of what people did. So they had these 42 Women complete a questionnaire of pregnancy in the past. So obviously, all of them had gone through pregnancy, they had returned to competition. And we’re looking at a retrospective thing here. So they broke it up. And I’m just going to describe the study real quick. They broke it up into five periods, they asked about the year prior to being pregnant. They asked about each trimester individually. And then they followed up a year after they were pregnant. I will say one limitation from this, all of the females involved in here were white. And they were from Australia, Canada, Ireland, Lithuania, Monaco, the UK in the US. So I don’t know if that is different. If we look at other maybe Asian or African populations, I don’t know. So I don’t know the the universal application of this. Anyway, not much to go into on methods on this tell you the truth. But let’s just talk about what they found. About 24% of the women in this study, decreased their training load prior to conception to help improve the chances of conception, interesting, their total training definitely decreased from pre pregnancy into pregnancy. And then when we go from pregnancy to post pregnancy, within about 14 weeks, 80% of the training load was back to what the women were doing. So relatively quickly, the women were able to get back to pretty much their highest level of trading before that, there really wasn’t a difference in the frequency of training from pre pregnancy, the women trained about nine times a week this is running and cross training, that came down to about six sessions per week throughout. And I’m pretty sure it was all running at that point, cross training was kind of cut out once women were in this pregnancy phase. But once they were in the pregnancy phase, all the women continued essentially six sessions per week. So they’re taking one day off of running, regardless of the trimester that didn’t change throughout pregnancy, volume definitely decreased very quickly. On average, they were running about 114 kilometers before. And that came down to 63 in the first trimester, and then down to 57. And then down to 30 in the third trimester. So big jump from free pregnancy into the first trimester, and then kind of relatively flat thereafter. So trading volume, you know, stayed relatively consistent in terms of frequency, and then relatively consistent throughout. But what did change a lot was intensity. And this was something that we had talked about with Dr. Sims previously, that intensity basically disappeared, as soon as individuals got pregnant. You know, they were, they were doing two hard runs, and three medium runs per week, that came down to one medium run and no hard runs once individuals got pregnant, and then rebounded again in that postpartum sort of phase. So just like Dr. Sims, was saying, the intensity side of things is definitely potentially hard, especially because nausea and other factors can maybe decrease the caloric intake that women have, which makes it hard to do this high intensity interval. The thing that I found really interesting so that that’s sort of done describing changes that they had in training. For me though, what was really interesting was the return to competition after about 60% of the women had planned to return to elite level competition, at least as good as they were prior. And essentially all of them were able to, in fact, there was a 5% 50% of the women saw a 5% improvement in their IWF ranking, meaning they were a better overall ranked athlete in the world based on IWF points after being pregnant. Really interesting. And I think that that is correlated with a lot of the anecdotes that I’ve heard that people return, if anything stronger. And, Trevor, I think that what Dr. Sims had mentioned, increased plasma volume, there are some other things that are physiologically are playing into why that is. Now the women did race a lot less after even though they returned to this elite competition, I guess being a mom’s pretty hard instead of

Trevor Connor  45:43

I don’t think that’s physiological. You think that they have a child? Exactly. It’s time. Yeah. So

Rob Pickels  45:49

they went from racing seven times a year to racing three times a year after which I hope that that’s a good thing. I hope that’s not an unfortunate thing that they’re missing four of these races, and husbands, you got to get out there and support your wives a little more, if that’s the case. So

Trevor Connor  46:04

I still remember, Chris loved Ray’s cross, and his wife was a cross racer, too. So when their daughter was a baby, they would split where fortunately, her race would always be right before his race. So while she was raising, he’d sit there and take care of the daughter. And then they would literally have like five minutes between the race to hand off the kid, and then Chris would go and raise so they figured out how to make it work. But it does add additional challenges. So

Rob Pickels  46:30

huge challenges. One of the biggest challenges that these women faced in this return to sport 50% of them. So that was 21 50% reported having an injury postpartum of that it was six bone stress fractures, no good 11, musculoskeletal injuries, to sciatic and to other injuries. And this was one of the biggest factors in individuals who are able to improve their performance postpartum, essentially, all of them who were able to be stronger after being pregnant, did not experience these postpartum injuries.

Trevor Connor  47:08

So they have an explanation or a thought on why that is, it’s a great

Rob Pickels  47:12

question, it was not correlated to any of the metrics that they, they they looked at in here. So it wasn’t the training volume after it wasn’t the frequency of high intensity, it wasn’t any event that they could draw correlation to. So frankly, I don’t know why personally,

Trevor Connor  47:29

just throwing this out there. What would be interesting, obviously, almost impossible to do at this point, would be to look at the nutritional habits, particularly during the pregnancy, as we talked about with Dr. Sims, when a woman is pregnant, priority is always given to the child. So if your diet is not great, and you’re not getting sufficient nutrients, it’s going to go to the child. And that’s actually going to make the mother extremely nutrient deficient, which can have impact on bones can have impact on muscles. So it’d be interesting to see if there was a difference in the die between the women that later experience injuries and those who didn’t.

Rob Pickels  48:06

Yeah, and that’s Trevor, you know, now Now that I’ve explained the study to you, because you didn’t get a chance to read it. I’d love to talk about that. Next, I think that this is a very formative beginning of research on international competitive women, that we could probably extrapolate to women, competitors of all levels, hopefully, my question is, where do we go from here? What do we need to know next, as athletes and coaches to get worthwhile information to to write training or to keep people safe? What’s the next study that should be done?

Trevor Connor  48:40

Well, as you were explaining this, to me, what was really interesting to me, you first of all, you pointed out, yes, it is completely possible for a woman post pregnancy to return to her former level or better, and actually get there fairly quickly. So that’s an important question that a lot of women have had where they felt I get pregnant. That’s the end of my career. And the answer that is no, it doesn’t have to be.

Rob Pickels  49:03

And this was they were looking within a year after pregnancy. So that’s pretty fast.

Trevor Connor  49:08

So that’s an important question. But I think the question that isn’t answered is the best way to go through that pregnancy to optimize health, as you said, some ended up injured, some didn’t. So what’s the best nutritional support? But also, I would love to see this. That’d be a tough study to do. I don’t know how you would do it. But my guess is women who continue to exercise through pregnancy? Probably have a How would you put us a more successful pregnancy than those who don’t? If you’re talking about success in terms of the mother’s health, post pregnancy, and that would be a very interesting study to do to look at women who don’t exercise during pregnancy, see what sort of impact as in their body versus those who do and if I’m right about that, that exercising through pregnancy is actually a very good thing. Then I think what needs to be figured out is what is optimal? How much exercise? Should you be doing know high intensity? Or is a little high intensity? Okay, these are all the things that I think need to be researched and figured out. Yeah. And

Rob Pickels  50:11

I wonder you would have to do that from a very large study, like a heritage type study, right? That’s just looking at a lot of people over a length of time. But I do think that that’s a really interesting way to look at almost a stratification of of activity level or training load, or however we want to quantify it. And also look at the health outcomes to begin filling in that blank, right, because the WH o basically recommends to female athletes, anything beyond 150 minutes per week, you should really talk to your individual care provider. And I bet you a lot of individual care providers, they don’t have any better information themselves, what are they left to go off of, besides intuition and gut feel, and maybe what they’ve done with their patients before? So filling in that gap can be really, really beneficial?

Trevor Connor  50:59

Yeah, I got the sense Dr. Sims implied this a little bit when we were talking with her. But unfortunate, I think a lot of primary care when they’re making recommendations to women who are pregnant, it’s based on a lot of past beliefs that really have no science behind them. And probably a lot of those recommendations are getting outdated.

Rob Pickels  51:17

And I think the easiest thing to do here is to be conservative, right? Yep, in the name of the health of the fetus. But as we’re learning the health of the fetus might actually be improved through this activity, right. And so instead of just being conservative in recommending kind of a minimum level, maybe we do need to figure out exactly what more of an optimal level is,

Trevor Connor  51:39

right. And that’s what I was getting at. I think, optimizing the level of activity, optimizing nutrition during pregnancy can have such a big impact on the outcome post pregnancy in general,

Rob Pickels  51:50

I’m happy to see that this research is coming out now. I’m happy to see all of the traction and information that Dr. Sims has gotten out to the world. But you know, this was a pretty large research group that pulled this together. You know, Dr. Trent Stelling worth, I believe was was one of the authors on here, among others. And I hope that we can continue to fill in these gaps because as athletes and coaches This is hugely important.

Trevor Connor  52:14

Great. Well, good study to spray on me. Rob. It was really interesting to read that one.

Rob Pickels  52:18

I thought it was I thought it was a good one. You know, Trevor? Jeff on this nerd lab.

Trevor Connor  52:23

I think I did to do I think I did to to get through the extra cans. Okay,

Rob Pickels  52:26

I got through the extra cans. Okay. Do you know what’s really funny though, is today is the first relatively cool day in Boulder, Colorado, and I immediately put on like jeans and a sweatshirt and I’m over here sweating through it right now because it’s not nearly as cold as I thought it was.

Trevor Connor  52:40

I had the same thought I was gonna put a sweater this morning like, it’s still sort of summer it is.

Rob Pickels  52:46

So you know, Trevor, I think maybe we wrap it up here and I can get out of this little podcast room.

Trevor Connor  52:51

All right. That was another episode of Fast Talk. Subscribe to Fast Talk wherever you prefer to find your favorite podcast. Be sure to leave us a rating and a review. The thoughts and opinions expressed on Fast Talk are those of the individual. As always, we love your feedback. Join the conversation at to discuss each and every episode. Become a member of Fast Talk Laboratories at and become a part of our education and coaching community. For Rob Pickels. I’m Trevor Connor. Thanks for listening!