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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Want to know the results of research on a particular topic of interest? Any questions about a supplement, food or intervention you’ve heard is the next big thing? Leave a question or a topic suggestion in the comments and I’ll sift through the papers for you.


Fuelling the engine. Competition carbohydrate consumption

Is doesn’t take a biochemist to know that carbohydrates are the MVP when it comes to fuelling high intensity exercise. But how much do we really need, and how do we know we’re putting in the right stuff?

Image credit: MabelaAmber via Pixabay

Our body has three main fuels to produce the energy required for the thousands of muscle contractions during an endurance sporting event. Carbohydrates are used predominantly when the pace is on, fats when the intensity is lower and once the carbs are gone and there’s less fat available the body will start burning muscle protein as a last resort.

In a high intensity event such as a bike race, where bursts of power could be required at any moment, readily available blood glucose is essential throughout a race to maximise performance. Endurance training prior to an event increases the mitochondria content in adipose tissue, essentially allowing greater energy production from fat sources over carbs. However, despite this being convenient for shedding some kg’s, fat oxidation is a much slower producer of energy than carbohydrate oxidation. Trying to race well off purely fat stores would be the equivalent of running a formula 1 car on diesel, the mileage may be better, but you’d be left behind easier than a phone charger in a hotel room.

Image credit: urv via Pixabay

We’ve established that we need carbs to go fast, but how many for a long race?

Quick answer: a lot.

Long answer: Carbohydrates ingested during a race aren’t the only ones that go into turning the pedals around, with glycogen stores in the muscles and liver playing an essential support role however one that will be addressed in a post in depth at a later date… To get an idea of how much to put in, first we need to calculate how much is going out (physicists get excited).

Say in a hard race a cyclist averages 292 watts (you’ll see why this number shortly…). The average power output on a bike is simply the total energy put into the pedals divided by the time taken to do it. In order to work backwards and find the energy spent the average watts are multiplied by the total seconds. So cycling at 292 watts for an hour (3600 seconds) requires 1,051,200 joules of energy (1051kJ more commonly). Unfortunately, our bodies aren’t 100% efficient, and only around a quarter of the energy spent by the body ends up making it into the pedals, with most lost as heat. This means that 1051kJ of energy into the pedals each hour requires about 4200kJ. Because we still haven’t made it to the metric system for measuring the energy in food that equates to a whopping 1000Cal per hour. A seven-hour race like the Melbourne to Warrnambool would therefore require more than twice the recommended daily calorie intake during the race to put in the same amount of energy that’s put out.

GP John Hannes Cup. A belgian Kermesse. I missed a few splits and spent a lot of time between groups this day averaging 294 Watts for 3h40min and burning close to 4000 calories

In terms of carbohydrates that 1000Cal per hour equates to around 250g of carbohydrate or 10 bananas. Before you go packing 70 bananas in your pocket it’s important to remember that carbohydrate isn’t the only fuel source during a bike race. A race with someone achieving a normalised power around 80% of their threshold will result in carbohydrates and fats providing close to an even share of the fuel supply. In the example above that would still require around 125g of carbs per hour, fortunately glycogen stores exist.

Image credit: durianrider

The task of putting in the same amount as you put out is made even harder by the fact that most people can only metabolise between 30-60g of carbohydrates per hour. Trained endurance athletes have been shown to reach 90g/h of carbohydrate metabolism but unfortunately this can’t be achieved as simply as shovelling down three or four muesli bars each hour.

To maximise absorption of carbohydrates in the gut it’s important to pay attention to which specific carbohydrates are put in. As one might expect, sugars are going to make their way into the bloodstream faster than complex carbohydrates, but there’s a few other tricks that can be used to max that carb absorption. Sugars make their way across the gut wall via a range of different specific transporters. The transporters can be thought of as gates that only let through their favourite sugars. If a mountain of glucose is poured into the system there’s only a certain few that can get through the gates into the blood at any time. But if some extra fructose is added then these have some unused gates to waltz through and get into the bloodstream, increasing the total carbohydrate absorption. (Before the biochemists send in the hate mail, it’s not quite this simple, with a bit more competition and a few more steps in the process but the principle is the same.)

Glucose molecules waiting to get through the gut wall. Image credit: skeeze via Pixabay

Studies have found that for maximum absorption a ratio of 0.7:1 of fructose to glucose is best. Rather than weighing up the ratios of apples to jelly beans during a race this is usually achieved with a pre-made drink mix. Increasing the absorption rate of carbohydrates in the gut by nailing these ratios doesn’t just help keep the blood-glucose at optimal levels but also allows for better fluid absorption and causes the gut to empty faster, preventing the bloating or discomfort riders often face when trying to stuff their faces with carbs mid-race.


With all this in mind, eating during a race can seem a lot harder than trying to rip the top off a gel without ending up with half of it on your top tube. Fortunately, our bodies are pretty good at keeping us going, particularly with training, and there are many other adaptions that help give those muscles their sugar hit when chasing those last few attacks. Well-planned carbohydrate loading and training the body to prioritise fat burning where possible allow endurance athletes to always have that little extra ready to go when they need it however good fuelling during the race is always important.

For races where you really want to be firing at the end (most I hope) try to get in around 60-90g per hour at a ratio of 0.7:1 fructose to glucose and you’re on the right track. Most importantly, work out what works best for you. It’s not always possible to smash 4 gels an hour and most people just prefer solid food so give a few different combos a try during some long training days and settle on a nutrition plan you can back in to have you feeling good and going fast.

National U23 Aus Champs 2018. I knew the race would only take around 2 hours and being well fuelled pre-race I did the race with one gel and some mineral water.

This topic had a lot to fit in, (fitting given the content) and ate into my Warrnie prep more than expected. Having loaded up on carbs the last few days and after a lot of fasted training to promote fat oxidation I’m confident I’ll be able to keep the blood sugar up throughout the race tomorrow. I won’t quite be aiming for the 90g/h mark on carb intake and given I’m racing solo with no team support I’ll be making do with whatever I can find out on the road in terms of bidons. Buying some fancy gels and drink mix would exceed my yearly salary of $0 so it will be a good chance to burn through all the leftover gels I’ve somehow accumulated over the past 12 months of racing. Hopefully they’ve got the sugar ratios I’m after and I can come home with some chocolates. Until then, I’ll keep reading the research papers so you can spend more time on the bike.



Request a Topic

Want to know the results of research on a particular topic of interest? Any questions about a supplement, food or intervention you’ve heard is the next big thing? Leave a question or a topic suggestion in the comments and I’ll sift through the papers for you.


Antioxidants or Antibenefits? Why Free Radicals are the unsung hero for athletes

‘Antioxidants’ is a word we see smattered all over breakfast cereal and juice packaging, but new research is telling us that athletes might need to lay off the goji berry extract if they want the most out of their training.

antioxidantsImage Credit:

The goodies

Antioxidants have received a more than decent wrap from the food and supplements industry. They’re talked up as being able to help with all kinds of medical conditions, from helping with eye-sight and joint function, to preventing Alzheimer’s disease and cancer.  This hype is great for the companies selling products rich in antioxidants, but it pays to know a little about just what antioxidants are and how they work before you buy a few hundred punnets of blueberries.

The baddies

Every hero needs a villain, and in this tale the villains are a type of free radical known as reactive oxygen species. Reactive oxygen species oxidise stuff, this is bad. Antioxidants antioxidize stuff, this is good.

The story should be straightforward, more heroes and less villains and the greater good prevails? Not quite, like any good superhero story this one has a twist… When it comes to exercise our radical villains play an important role, just enough to make you think twice about whether to barrack for them or the hero.

free radical‘Free Radical’ by Kelly Frew via Flickr

What happens when you train?

Radicals build up within the muscle during intense exercise. Basically, the more oxygen consumed by the muscle, the more oxidative stress from reactive oxygen species (radicals). The stress caused from the radicals then causes damage to the muscle. Now this damage isn’t exactly making our villain sound any more heroic, however, these small amounts of damage are crucial for athletes to see the benefits from their training.

Free Radicals are actually pretty radical

The presence of these radicals causes the release of signals within the muscle telling the muscle to repair itself and better prepare for future oxidative attacks. Think of it like a bunch of bad guys attacking a city. The bad guys don’t do enough to destroy the city completely, the city rallies together, fixes the broken buildings and builds some better walls to defend against the next attack.

Free Radicals do a little damage to the muscle during training so the muscle can repair and become better equipped for the main competition.

Castle.jpgImage Credit: Destinations Journey via Flickr

So, radicals aren’t all bad, but what’s wrong with antioxidants?

If there’s too many heroes around, the villains never make it to the city. This is fine if you’re happy in a small town that will never face attack. But if you’re an athlete you’re striving for a big, powerful fortress that can cope with anything. If the muscle never faces oxidative stress then there is nothing to promote repair and improvement. In the presence of too many antioxidants all that hard training could be going to waste!

I just ate a cranberry; will I have any muscle left by tomorrow?

As is the case with almost all nutrients in the diet: moderation is key. There is still a long list of benefits associated with antioxidants. This new research suggests for athletes to get the most out of their sessions it may be best to avoid overdoing the vitamin supplements and go easy on the goji berries in your post-workout smoothie.

goji berriesGoji Berries. Image Credit: Leslie Degner via Flickr

Further reading:


My first race with the team will be the Gravel and Tar Classic next week in New Zealand. Hopefully a good week of training and watching the antioxidant intake will have me ready to go! Until then, I’ll keep reading the research papers so you can spend more time on the bike.



© Cyrus Monk 2019