Leah:

Hello and welcome to the Ideal Nutrition Podcast. I am Leah Higl and I’m here with my co-host Aidan Muir. And today we’re going to be talking about pre-training nutrition, specifically in relation to answering the question, does eating before exercise actually improve performance and what does the research show? So we’ll talk about this both in relation to endurance training, endurance sports and resistance training.

It is a really common thing for dieticians to say you need to eat before training. Like if you eat before training, particularly having a high amount of carbs, you will perform better. But I think it would be great to just unpack the research around this and really talk about the context in which it really matters. And maybe the context in which maybe it doesn’t matter as much.

So starting with a little bit of theory, there are a few theoretical reasons why this could matter and could improve performance. So carbs before the session obviously can increase the amount of glucose you have access to and or glycogen, which could allow the body to train at a higher intensity for longer due to having more easily accessible fuel on board. There is even evidence that potentially things like mouth rinses with carbs can help with performance, like literally swinging carbs and sugary stuff around in your mouth and then like spitting it out can actually lead to improvements in performance, which I think definitely builds more of an argument around this concept and the several roles or ways in which pre-training carbs may help outside of even just having more energy and more fuel to pull from.

There could also be benefits related to electrolytes and even other nutrients that are contained in different foods. Again, outside of it just being carbs equal fuel, fuel is good for performance. So in saying that, how you feel prior to training and during your training session also plays a huge role in performance. Like if you feel good and you’re nice and full, but not too full and gastrointestinal, you’re feeling really good, you’ve got energy, you’re probably gonna perform better. So even again, not taking into account all that other stuff, but just feeling good can improve performance and food can play a role here. And then also the timing and the food choices come into play when kind of delving into that a little bit more deeply.

Aidan:

We’re going to split this up into endurance and resistance training because they’re kind of separate topics in a way with this. Like we’re talking about carbs like before exercise, but they both kind of deserve their own thing. So I’m going to start off with endurance stuff. So firstly, it’s very common for guidelines to recommend certain targets. Like I was looking for guidelines to kind of share. And the first one that came up for me is Academy of Nutrition and Dietetics.

basically recommend one to four grams per kilogram of body weight carbs one to four hours before a session. So it’s like a decent amount of carbs before the session. So that’s like the general recommendation, but like what does the research actually show? So I’m going to talk through a few studies. I didn’t cherry pick. I just went through like study after study after studying. It kind of got to a point that it was a very similar conclusion. So like the first study, 2.5 grams per kilogram of body weight carbs pre-exercise versus placebo during a time to exhaustion run at 70% of VO2 max found a noticeable improvement.

Study two, three grams per kilo carbs versus 0.5, so higher versus noticeably lower, three and a half hours before a time to exhaustion test. Once again, high carb group outperformed. Study three, 70 grams of carbs from rice two hours before, and then also 74 grams of carbs during a 21 kilometre run, so a half marathon. The carb group outperformed again versus like that no carb group. And it’s just this endless list of carbs before endurance activity, if it is long enough and hard enough, typically outperforms. But those are the kind of key points there. It has to be kind of both long enough and hard enough.

Because for example, if you were doing like a chill zone to run or ride or anything like that, even for quite a long duration, it’s not really going to matter for performance specifically. And in those ones, you’re not even trying to optimise performance. But it’s worth thinking about, like if you’re trying to do anything that is intentionally harder and you care about performance more, in the vast majority of cases, it helps, which makes sense because those are very glycogen intensive activities.

Leah:

Moving on to resistance training. So the same concepts definitely do apply. The only difference is that resistance training doesn’t have as much glycogen glucose utilisation as endurance training, especially like hard endurance training that’s happening for quite a prolonged period of time.

We often reference this particular study though, which had their participants do six sets of leg extensions to failure being kind of the key word there. And that depleted glycogen stores by around 40%. So there is obviously quite a bit of glycogen glucose utilisation in resistance training, particularly when we’re higher rep, like failure training, like your kind of bodybuilding style stuff. And that tells us two things.

One is that if you are fully carb loaded, so in the context of a quite a high carb diet in general, it’s probably rare to fully deplete glycogen stores by lifting weights and just doing resistance training, even if you are training quite hard. But if you had low glycogen stores in the concept of an overall or context of an overall, it may be low to moderate carb diet at baseline. Maybe this does start to matter more. So if you don’t have as much quote on quote fuel in the tank, and you’re depleting your stores during resistance training, there probably is a point where it does start to actually impact your performance, but you are obviously using less of this stuff in resistance training than endurance training.

Looking at the research. So there are two big meta-analysis on this topic that came out in 2022 that had different findings that caused quite a bit of discussion and arguments amongst people in this space. One by Menno Henselman that found there was no difference in performance when looking at resistance training and having pre-training nutrition versus none.

And another by Andrew King and colleagues that found a difference under specific circumstances. So there were differences found in that particular analysis with the circumstances being the sessions being over 45 minutes long and would otherwise have been occurring in a fasted state. So looking at the kind of breadth of research, there is obviously, it’s not quite as clear as the endurance training stuff but depending on the context that we’re talking in, it still matters.

Aidan:

I’m gonna share some other thoughts just in general. how you feel obviously matters heaps like that impacts the session more, like not more, it impacts the session alongside like the physiological stuff in terms of like how much glycogen you’ve gotten, everything like that. I’m really big on this. Like I’m really big on this.

From the resistance training perspective, the example I have very clearly in my head is how I felt after three sets of high rep sets on hack squats. Cause I feel like I want to throw up basically. If I did that same thing after eating too close to a session, I will feel like I want to throw up. If I have not eaten for a very long time going into that session, I typically would feel lightheaded much sooner and feel like I would assume on that third set, I would be getting noticeably less reps just because of how I feel.

And there’s kind of like that just right sweet spot in the middle. And I find the same thing with running as well. Like I find even the zone two stuff, some of it has really shocked me just being part of like the running scene in a way is that there’s been many like long duration zone two ones where I’m like, it doesn’t really matter if I’m like, if I’ve had enough carbs or anything like that. And then like I’m halfway through, I’m like, I feel trash.

And literally just eating a little bit more before like makes me feel great. like how I feel definitely, I think matters in terms of how it impacts the session. But also I don’t think it shows up in research anywhere near as much as you’d think just because in research you’re pushed to failure and how you feel seems to matter less when you’re giving a max effort than when you’re in a gym alone without any kind of like accountability in a way. That’s my own two cents. And it’s also what I see.

Other stuff though, back to the nutrition side of things really. We’ve largely focused on carbs, but obviously other nutrients matter. So one of the big ones I want to talk about was sodium. So we don’t have as much research as I’d like on sodium pre-workout, but a common one that both of us have spoken about is if somebody feels like lightheaded in the gym, sometimes having more salt or sodium pre-workout solves that. That’s an easy win. If you don’t feel lightheaded, you’ll probably get more reps out and stuff like that. People would often get better pumps as well in terms of like more blood flow and stuff like that.

And then for endurance stuff, a bit of an argument sometimes for like a sodium preload helping with hyper-hydration, which can also be relevant to another one that I don’t have an opinion on yet, but the research has shown that magnesium levels drop a lot during exercise. If somebody’s training intense and for long periods of time, is it worth taking steps to offset that? I don’t have an opinion on that yet, but we do have research showing that you can offset that by having magnesium before you train.

Maybe one day we’ll find out that that’s meaningful. Maybe we won’t. We’ll see how it plays out. And the other one that’s not as relevant, but it’s just an example of like, there’s so much you can do pre-worker that can help performance. Dietary nitrates. So often we’re often looking at like beetroot juice and stuff like that, but dietary nitrates help with vasodilation, blood flows more easily. And this clearly helps with endurance performance. And it also helps with higher rep resistance training as well. So I’m using that just as another example of like, even if we’re not even just looking at carbs, there’s some stuff in pre-workout nutrition that can help with performance.

Leah:

So what is our overall interpretation of this space? I think in most cases, it makes sense to distribute at least a portion of your calorie and carb intake pre-training, but there obviously can also be exceptions. So if you do prefer to train fasted and you’re not overly concerned about maximising performance in these sessions, then

Right. It matters a little less. It’s just not your overall goal. Maybe your goal is just to move your body in a way that feels enjoyable. Cool. Do that. But from a performance perspective, think at minimum ensuring that you at least have a decent amount of glycogen stores prior to training in terms of whether that’s endurance or resistance just makes sense if you care about performance.

Aidan:

This has been episode 195 of the Ideal Nutrition Podcast. As always, if you could please leave a rating review, that would be greatly appreciated.