Intra-Session Protein for Performance; Yeah or Nah?

Cycling requires repetitive contractions of big muscle groups for hours on hours, so why isn’t anyone reaching for a protein shake mid-ride?

Image credit: 926663 via Pixabay

In my time working in gyms I’ve seen some a common occurrence amongst lifters – If someone’s hitting the gym for longer than an hour, a protein shake will likely be in hand between sets. Cycling can have ridiculous demands on the body and it raises the question of whether cyclists should be the ones with a protein shake mid-ride? Not only can cycling be taxing to the body, but, protein itself plays some interesting roles which suggest it could have a positive impact on performance.

  • Protein is a macronutrient (alongside carbohydrates, fats and alcohol).
  • protein can be converted to glucose (the form of carbs the body prefers).
  • protein will be oxidized (burnt) in endurance exercise.

Given these facts, it begs the question of whether mid-ride protein supps would have a positive effect on performance.

To be specific we are asking “what are the effects of intra-session protein supplementation on acute endurance cycling performance outcomes”. We aren’t looking at whether protein makes you recover for the next session or whether protein makes you feel less sore after a ride, etc etc. A bunch of that stuff we might tackle in the coming weeks.

Interestingly, there isn’t a great deal of data on endurance performance and intra-session protein supplementation. Don’t get me wrong searching for “effects of protein on endurance performance” will return heaps, but none of these results look at exactly what we are after.

There is so little out there that I couldn’t find a single paper that compared protein alone to placebo, carbs or carbs+protein. Not a single paper. Confirming my lack of results, a 2014 systematic review didn’t find a single paper on our topic. (Effects of Protein Supplements on Muscle Damage, Soreness and Recovery of Muscle Function and Physical Performance: A Systematic Review YEAR). The lack of research isn’t that surprising. The pathways of energy production in skeletal muscle are well known and, as we’ve seen, carbs are king. Researchers aren’t as likely to look at protein alone as carbs have such a well-documented effect on performance.

Image credit: jarmoluk via Pixabay

And with this we have an answer to our original question:

Q: “if I want to go faster in a long training ride or a long race should I swap out my carbohydrate sports drink for a protein supplement?”

A: “Probs not, stick with the carbs”

Or you could say “at this stage, it appears that intra-session protein supplementation alone is extremely unlikely to cause any significant improvement in performance. With that said, there are few if any good studies that directly compare protein to other supplements so there is a small chance that it does have a positive performance effect but, as of yet, it is unlikely.”

I did find another question which is relevant.

“What is the effect of intra-session supplementation of carbs AND protein on performance?”

This one has more research. Rather than go through all the papers I found, here is a nifty figure from a review on the topic which we’ll breakdown to look at some of the nuances of this topic. (Is There a Need for Protein Ingestion During Exercise? 2014)

figure 1 cal
Studies investigating improvement in performance with intra-session carbohydrate + protein supplementation compared with carbohydrate alone. White bars are studies that use Time To Exhaustion (TTE), black bars are studies that used Time Trial (TT) as a performance metric. Credit: Is There a Need for Protein Ingestion During Exercise? 2014

At first glance it looks like carbs + protein is amazing for performance! But, there is more than meets the eye. Before we break it down, lets chat carbs quickly. The body is great at getting carbs from your gob into your muscles (suss out the last blog for more on this). On average about 60gms of carbs can be ingested and used per hour, so an optimal carb supplement should provide about 60gms of carbs per hour.

In the trials from the graph, they all used a similar format: a cyclist would ride a TTE (time to exhaustion) or TT test. Once with a carb drink (C) and then another time a few days later with carbs + protein (C+P) and the researchers would compare the times from the (C) to the (C+P).

With our knowledge of optimal carb supps lets break the trials down into 2 groups

  • “Optimal” Trials that used 60gms of carbs per hour in both (C) and (C+P). (trials from the above graph that had optimal carb supps were: Breen et al (2010), Osterberg et al (2008), Sanders et al (2009), Valentine et al (2008), Van Essen and Gibala (2006)
  • “Sub-optimal” Trials that used less than 60gms of carbs per hour in both (C) and (C+P). (trials which had sub-optimal carb supplementation were: Ivy-et al (2003), Lee et al (2003), Martinez-Lagunas et al (2010), Romano-Ely et al (2006), Saunders et al (2004), Saunders (2007)

When I replot the graph without the “sub-optimal” trials(<60gms of carbs per hour) the graph tells a different story

figure 2 cal
First graph with studies using sub-optimal carb delivery rates taken out. Credit Is There a Need for Protein Ingestion During Exercise* I couldn’t work out carbs per hr for Madsen (1996) and G Van Hall et al (1995) so we’ll give them the benefit of the doubt and leave them in.

Crazy how much this changes the picture! The effect size goes from quite large to either very small or non-existent. It’s pretty clear that when there are enough carbs delivered (>=60grams  per hour) adding protein doesn’t improve performance.

This makes sense when you think about it, carbs (and fats) are the fuel/s for endurance work. The body is great at burning them, great at storing them and great at delivering them from the gut and liver to the muscle to keep the body moving. So when the fuel tanks get low and you’re filling it up with fuel via a carb + protein drink the body will be mostly using the carbs, assuming there are enough carbs provided by the supplement. We see the theory work out in practice here: when a trial compares an optimal carb supp (C) to an optimal carb supp plus protein (C+P), there is little difference in performance.

Image credit: IADE-Michoko via Pixabay

For something of more scientific merit than the homemade graph from above,  a systematic review on the topic concluded:

“it was also evident that when carbohydrate supplementation is delivered at or above 60 g·h−1, protein supplements provide no further ergogenic effect, regardless of the performance metric used”

Still, we saw that some of the “sub-optimal” trials had a performance improvement in the (C+P) group compared to the (C) group. The thing to remember is that in these “sub-optimal” trials the (C) and (C+P) were getting less than 60gms of carbs per hour, but the (C+P) group is getting extra calories from the protein and these extra calories might be helping fuel performance. Some of these trials delivered less total calories than an optimal carb supp would, this means that sub-optimal carbs intake + some protein may help performance more than just a sub-optimal carb supp. So you might get a small performance benefit from adding in protein if you’re short on carbs and there’s nothing else available.

Take home messages:

  • there isn’t much data on whether intra-session protein (alone) supplementation is good for performance, but, it is unlikely to help.
  • If you’re consuming less than 60gms of carbs per hour (ie trying to reduce caloric intake) adding protein may help you perform better
  • If you’re consuming the optimal level of equal to or more than 60gms of carbs per hour on a ride adding protein won’t help you go faster.

So intra-session protein for cycling performance?

The research says nah. Getting your 60gms of carbs in per hour is your best bet.

Image credit: maxmann via Pixabay

Callum Baker

PhD Candidate | Accredited Exercise Physiologist | Clinical Teaching Fellow
The University of Sydney


A huge thanks goes to Callum for producing this article for Cyclist or Scientist. Great to have a PhD Candidate writing for the website in an area of expertise and I hope you gained a few handy pointers from the article. As for myself, I’m in Australia for another few weeks of training in the sunshine before heading over to Europe to get stuck into some racing with EvoPro. Until then, I’ll keep reading the research papers so you can spend more time on the bike.



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3 thoughts on “Intra-Session Protein for Performance; Yeah or Nah?”

  1. Interesting article again. Like you point out, the research on protein intake during exercise seems to be none-existent. I used to believe the hypothesis that about 5-15% of your caloric utilisation comes from protein (gluconeogenesis), and if you don’t supply the needed protein, your body will catabolise it from your own muscle tissue, which could lead to premature muscle fatigue due to excess ammonia from the protein breakdown process. Soy protein apparently does not readily produce ammonia, whereas whey protein contains glutamine which metabolises increasing ammonia (before eventually scavenge ammonia, but it takes some time ~ 3hours). Soy protein also has a high level of aspartic acid, which plays an important role in energy production via the Krebs cycle high levels of phenylalanine and tyrosine, which may aid in maintaining alertness during extreme ultra distance races.

    More recently I’ve trended towards the glucose : fructose 2:1 based on Asker Jeukendrup research and the ability to train SGLT1 / GLUT-2 (glucose) and GLUT-5 (fructose) transporters. I suspect a protein source might (?) interfere with that process? But no research to confirm…possible PhD study right there…

    I’m not super familiar with absorption and assimilation but I remember that the small intestine has villi (like fingers), and I imagine with a load of food / bars and fats and protein those fingers will get all clogged and their surface area limited for CHO absorption and will therefore not be as effective as the stomach / intestine pH, enzymes, osmolity all struggle for the perfect equilibrium they need. That’s the way I think of it. I ain’t no medical person tho.


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