Why Cyclists May Need More Protein On Rest Days?

As an athlete, a huge amount of our physiology, is largely made up of protein. From the individual muscle fibres which contract to turn the pedals, to the mitochondria, which provide the engine for the muscles, the blood vessels and blood cells carried within them, to the cells within the immune system that fend off illness and infections, they are all primarily made up the amino acids which we consume from protein-containing foods within our diet.

Protein not only provides the building blocks for these tissues but, in the case of the muscle, is a key trigger for the growth of new muscle tissue. As such, our protein intake is a critical dietary consideration to stay healthy and help maximise the adaptive response to training when looking to enhance our performance.

 As such, as a cyclist, we generally want to optimise our intake of protein in our diet to help maximise the benefits of training, with a key focus on the total amount of protein we consume, the timing of its intake and the type of protein that we consume within our diets.

Whilst much of the research to date on protein for athletes has focussed on resistance exercise and muscle hypertrophy (i.e. growing new muscle tissue), protein also plays a key role in supporting performance and recovery as a cyclist and there is growing interest in the impacts of protein on endurance training adaptations and protein needs for endurance athletes.

Endurance athletes actually tend to have elevated protein needs and may require more protein than gym-based athletes looking to maximise muscle building. As such, there is a need for specific recommendations for cyclists.

This greater requirement for protein in endurance athletes is largely down to the increased breakdown of protein that occurs during exercise, particularly when glycogen availability becomes limited (as is often the case on rides longer than a few hours), as protein is broken down into glucose to help fuel the exercise task.

As a nutritionists, when working with athletes, we generally look to keep protein intake fairly consistent across a week, with no major fluctuations on a day-to-day basis, beyond possibly slightly higher intakes on days where overall energy expenditure is much higher or during times of energy restriction to help preserve muscle mass. However, new research suggests this might not be optimal.

A recent study has looked to evaluate the impact of a rest day vs training days (consisting of either a 5km or 10km run) on an individual athlete’s protein needs. The study utilised a cool technique that, whilst it doesn’t allow us to determine the precise amount of protein that was needed for an athlete, did give an indicator as to whether or not a protein intake was sufficient for the exercise task.

The study showed that protein needs for endurance athletes may actually be higher on rest days (~12-24h after the last exercise bout) than on training days. Which may seem counterintuitive but is potentially a result of the requirement to replenish a greater negative muscle protein balance during the overnight fasted period (i.e. when an athlete is asleep and not digesting food). This has significant implications for how to structure an athletes protein intake to maximise the adaptive response to training.

From a practical perspective, rest days often have lower energy requirements (due to less training), and with training potentially sensitising the muscles to protein feedings for as much as 36 hours post-exercise, it is certainly worth prioritising the intake of protein on rest days. Protein foods also tend to be quite filling/satiating,his can help an athlete manage appetite on days where energy requirements may be lower.

As such, whilst we can’t yet give you a specific intake to aim for on a rest day, as an athlete it is certainly worth prioritising your intake of protein on rest days. For most endurance athletes,raining loads, intakes in the region of 1.6-2.2 grams of protein per kilogram of body weight should be sufficient. 

Coach Ben 

Reference

Moore, D. R., Gillen, J. B., West, D. W. D., Kato, H., & Volterman, K. A. (2024). Protein requirements may be lower on a training compared to rest day but are not influenced by moderate training volumes in endurance trained males. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme, 49(8), 1124–1128. https://doi.org/10.1139/apnm-2023-0297