How important is protein for recovery in cycling?

Consuming large amounts of protein after training is part of the mythology of elite athletes. But what does the science say? And aren’t there supplements for this? Dr Brendan O'Brien takes us into the science behind protein and its relationship to recovery and performance.

How much protein does your body need?

Protein is an important structural component for our cells and organs. There are at least 20,000 kinds of proteins in the human body, formed by different combinations of only 20 amino acids – the basic building blocks of all proteins.

An average adult body contains 10-12 kilograms of protein, with 6-8 kilograms (60-75 per cent) in muscles.

Due to metabolism, the body degrades and synthesises about 1-2 per cent of the body’s total protein each day, and to ensure muscle mass is maintained, people need to regularly consume protein to replace the protein that is degraded.

If not undertaking heavy training, it’s generally recommended people eat about 0.8 grams of protein per kilogram of body mass each day. For example, a 70-kilogram person should aim to eat 56 grams of protein a day.

When resting, most of our energy is derived from burning fat and carbohydrate. However, protein metabolism also contributes to between 2-5 per cent of our body’s energy requirements.

The body also uses up fat and carbohydrate to sustain output when undertaking prolonged exercise such as cycling, but as the carbohydrate stored in muscles diminishes, the body uses up more protein from muscles.

This type of protein metabolism may contribute 10-15 per cent of the energy requirements during four hours of continuous cycling, so extra protein is required by cyclists who ride for prolonged periods.

Protein intake recommendations for endurance athletes are 1.2-1.4 grams per kilogram of body mass per day. However, Grand Tour riders aim to eat 2-3 grams of protein per kilogram of body mass per day, so a 65-kilogram Grand Tour cyclist would potentially eat 195 grams of protein each day.

For perspective, a 150-gram steak contains 40 grams of protein. A 100-gram chicken breast contains 30 grams, while three large eggs contain approximately 20 grams, as does 600ml of dairy milk.

Most recreational cyclists do not require the protein requirements of a Grand Tour rider, but should aim more for 1.2-1.4 grams of protein per kilogram of body mass per day.

Timing is essential

While dietary protein supplementation during cycling generally doesn’t provide additional benefits beyond what carbohydrates provide, there appears to be benefits in ingesting protein after cycling for several hours, to compensate for elevated protein metabolism and muscle degradation.

A 2018 study compared the recovery performance of two groups of cyclists after they cycled to exhaustion. The first group consumed carbohydrates only after cycling, while the second group consumed carbohydrates and proteins.

Eighteen hours after eating, all participants completed a 10-second sprint test and a 26-kilometre cycling time trial.

Compared with the carbohydrate-only group, the power output of the carbohydrate and protein group was 3.7 per cent higher during the 10-second sprint, and their time was 8.5 per cent faster in the 26-kilometre time trial, suggesting there are clear advantages in consuming protein after an exhaustive training session to enhance recovery and performance the next day.

There also appears to be a limit in how much dietary protein is required to maximise protein synthesis, with another study showing that 30 grams of milk protein during recovery stimulates muscle protein synthesis, but increasing the amount to 45 grams did not result in additional muscle protein synthesis.

Accordingly, it is recommended that daily protein consumption be dispersed over three to four meals every 24 hours to optimise muscle synthesis and recovery.

No all proteins are created equal

Figuring out the best kind of protein to enhance recovery is an ongoing area of research. Generally, meat, egg and dairy products are superior to plant-based proteins, as they contain the most anabolic amino acid, called leucine. However, for many people, supplements are the most convenient method of loading their body with protein.

The most common protein supplements are powders derived from whey and casein proteins, which are by-products from converting cow’s milk to cheese.

Many vegetarians opt for protein powder derived from soybeans. Soy protein has shown to be potentially just as effective as whey for enhancing muscle synthesis when matched for leucine content.

However, cyclists should be cautious of protein supplements.

The potential harm of supplements was revealed by The Clean Label Project in 2018, which tested 134 of the top-selling protein powder products according to Amazon.com.

Disconcertingly, the project found that approximately 75 per cent of the tested supplements had measurable amounts of lead, and that plant-based protein powders contained twice the amount of lead per serving than other protein powders.

Additionally, many plant-based protein powders contained mercury, cadmium, and arsenic, in several cases above health-based guidelines, and 55 per cent of the protein powders tested had measurable amounts of BPA, an established endocrine disruptor.

So, what red flags should you look for when considering a protein supplement? To protect your health, the Australian Therapeutic Goods Administration (TGA) advises:

• Don't buy from overseas websites
• Look for an AUST number on the label, which confirms it is a TGA regulated product
• Seek advice from a health professional before using a new product
• Consider alternative options when aiming to enhance your fitness or physique

In 2020, the TGA cracked down on the then-poorly regulated sports supplement industry to improve the health and safety of the public.

Therapeutic supplements promoting sport and physical performance capabilities are no longer to be supplied unless they comply with TGA legislative requirements, and the Australian Sports Anti-Doping Authority (now Sport Integrity Australia) recommends that athletes only use supplements that have been tested by an independent body.

Accordingly, the importance of consuming nutrient and protein-dense whole foods should not be under-estimated, as whole food is more likely to result in workout success than protein ingested through isolated or “deconstructed” protein supplement powders.

Dr Brendan O'Brien is a Senior Lecturer in exercise physiology and exercise prescription at Federation University.

His current research interest is in optimisation of exercise prescription based on individual differences in physiology. In particular, Brendan is focusing on identifying reliable and sensitive physiological biomarkers that can predict the “trainability” of individuals to endurance and resistance training. He has published more than 40 journal articles in Exercise Physiology.

This article was first published by AusCycling. Click here for the original article and the full list of references. This content is part of a series by Federation University experts in the lead-up to the 2023 Federation University Road National Championships which will be held in Ballarat and Buninyong from January 6-10. For more information, visit the Road Nationals website.