Recovery nutrition: is the window of opportunity real?

When it comes to post-exercise recovery, there are two key ingredients. The first of course is getting physical rest, which includes plenty of sleep. But without doubt, the next single most important thing you can do to boost performance is to improve your recovery nutrition! In broad-brush terms, there are four major nutritional requirements for rapid recovery after long and/or strenuous exercise (see box 1). Of these nutrients, carbohydrate is the most researched, and over recent years, much has been written about the benefits of consuming carbohydrate following exercise (see these articles). 

Box 1: Nutritional requirements for rapid recovery

• Carbohydrate – needed to synthesise and replenish muscle glycogen (the body’s premium grade fuel for strenuous exercise), and also to top up liver glycogen stores, which serve as a reserve to maintain correct blood sugar levels. Post-exercise carbohydrate also stimulates the release of a hormone called insulin, which helps to drive glucose (from carbohydrate) and amino acids (from protein – see below) into hungry muscle cells, accelerating recovery;
• Protein – needed to supply the amino acid building blocks required to repair and regenerate muscle fibres damaged during exercise, and to promote muscle hypertrophy (growth) and adaptation;
• Water – to replace fluid lost as sweat and to aid the process of glycogen storage in muscle (each gram of glycogen synthesised in muscle requires around three grams of water to ‘fix’ it in place;
• Electrolytes – to replenish minerals lost in sweat (eg sodium, chloride, calcium, magnesium).

However, protein is also known to be important for post-exercise recovery. While protein metabolism is more difficult to study, increasingly advanced scientific techniques over the past 15 years or so have helped to shine a light into post-exercise protein intake and its role in recovery. Importantly, sports scientists have begun to fully appreciate why protein is so important for endurance athletes such as runners, cyclists and triathletes. While it’s true that these sports don’t require high levels of muscle mass or brute strength, consuming adequate protein to regenerate muscle mass broken down during exercise is absolutely vital for all the reasons listed in box 2.

Box 2: The importance of muscle mass for endurance sports

• All other things being equal, a muscle with a larger cross-sectional area is able to generate more force and power (ie is stronger) – force needed to propel you forward whether swimming, cycling, rowing, running etc;
  The higher the peak force and power your muscles can produce, the easier it is for them to maintain a given workload (eg force applied to the cranks during cycling, or powering through the water when swimming) because they can do this by working at a lower % of their maximum force output;
  More muscular strength and power allows for better sprint performance (eg at the end of a race or to break away from your opponents);
  Stronger muscles are better able to withstand the stress and strains of repeated impact and loading – ie reduce your risk of injury.

The carbohydrate-protein recovery combination

While carbohydrate is absolutely essential for replenishing muscle glycogen – a key component of recovery - research has established that carbohydrate and protein work synergistically in the body, which means that better recovery is achieved when the two are combined in post-exercise feeding rather than either taken alone. In a study on cyclists, researchers looked at muscle protein synthesis and different recovery formulations after high-intensity cycling⁽¹⁾. 

Twelve cyclists completed 100 minutes of high-intensity cycling, then over the next four hours at hourly intervals, ingested one of three recovery drinks:

• 70g protein/180g carbohydrate/30g fat (high protein)
• 23g protein/180g carbohydrate/30g fat (low protein)
• 0g protein/274g carbohydrate/30g fat (zero protein)

All the drinks were effective at helping restore muscle glycogen (thanks to the carbohydrate content) but it was only the protein-containing drinks that were effective at promoting muscle tissue synthesis and recovery. Interestingly, the low-protein recovery drink containing only a third of the protein of the high-protein drink stimulated muscle tissue synthesis almost as well (see figure 1). This is likely because the protein used in these drinks (whey) was rich in the amino acid leucine, which plays a special role in muscle recovery – probably by acting as a ‘signalling molecule’, helping to switch on genes involved in muscle protein synthesis.

Figure 1: Muscle tissue synthesis: zero vs. low vs. high protein recovery drinks