A glass of cow’s milk: is it the perfect recovery drink that it’s made out to be? Part 1

Posted by Simone do Carmo

In the past decade, milk has been widely researched as a workout recovery aid. It has a balanced ratio of protein, carbohydrates and fat, plus vitamins, minerals, water and electrolytes – in many ways, the perfect post-exercise beverage because it satisfies the key components of recovery by replacing fluid and nutrients after an intense training session. But is it suitable for everyone? And what about the quality of milk?

Let’s look at a glass of cow’s milk:

There’s roughly 10g of protein in a glass of milk. The whey protein in milk is high-quality because it contains an ideal balance of rapidly-digested essential amino acids and branched-chain amino acids, such as leucine, which promote muscle protein synthesis by stimulating the mTOR pathway. Milk further contains casein, which is also high-quality, but considered a ‘slow’ protein because it’s emptied at a slower rate into the stomach. This allows for a more prolonged rise in plasma amino acids and is why consuming casein before bedtime has become popular.

Milk provides roughly 5g of carbohydrate per 100 ml (similar to commercial recovery drinks) in the form of lactose, that stimulates insulin production. The increase in insulin activates glycogen synthase – the key enzyme involved in glycogen re-synthesis.

As milk comprises roughly 90 per cent water and electrolytes, such as sodium, potassium, calcium and magnesium, that are lost through sweat during exercise, it’s a suitable drink for rehydration. In a recent study, 12 male participants were randomised in a crossover manner to drink either water or low-fat milk equal to the volume of sweat lost during a moderate intensity cycle (1). They consumed these beverages at different times: 30min or 90min post-exercise. The results showed greater total fluid retention when milk was consumed, while no effect on drinking rate was observed. In addition, perceived fullness was higher at 90min after drinking low-fat milk compared to water. This may affect subsequent energy intake and thus promote positive body composition changes – an effective and subtle nutritional strategy for weight management.

The vitamins and minerals in milk are essential for maintaining good health: a pillar for optimal performance that we recognise here at the Centre for Integrative Sports Nutrition. It provides vitamin D with its myriad of bodily effects; namely, helping the body to utilise calcium and phosphorus for bone health. It’s also a source of iodine for thyroid health, vitamin B12 for healthy red blood cells and nerve functioning, and vitamin A for maintaining healthy tissue growth and vision. Milk is also well-known as one of the best sources of calcium for strong bones and proper muscle functioning.

So much is packed into a simple glass of cow’s milk. But how does this relate to athletic performance and recovery?

Various studies over the past decade have highlighted milk’s effectiveness for athletes. Rankin et al randomised 32 (16 males and 16 females) team-sport players into two groups: 500ml of semi-skimmed milk or 500ml of a isocaloric carbohydrate-based drink after exercise (2). The researchers found that consuming milk was likely beneficial for attenuating muscle function losses in females. Milk also reduced the increase in muscle damage markers and muscle soreness from baseline to 72 hours post-exercise. A more recent study by Rankin et al found that 500ml of milk limited muscle function losses after repeated sprinting and jumping in female team-sport athletes when compared to an energy-matched drink (3).

Other studies have supported milk’s effectiveness in recovery. Some have also shown improvements in aspects of performance. A study by Cockburn et al randomised 14 healthy males to drink either 500ml of semi-skimmed milk or 500ml water (control) after exercise (4). The researchers found that ingesting milk was effective at attenuating exercise-induced muscle damage and demonstrated improvements in agility, one-off sprinting, and repeated sprints during a validated test called the Loughborough Intermittent Shuttle Test, which simulates the physiological demands of field-based team sports. A downside of this study was the use of water as a control. Using an energy-matched drink would have eliminated any possible performance-enhancing benefits from the additional energy intake provided by milk. There is also a need for more cross-over studies to exclude any inter-individual variability among the participants as most studies use an independent group design.

Milk lastly contains bioactive compounds that are recognised for their specific immunomodulatory effects to promote an anti-inflammatory response. Whether this anti-inflammatory response plays a role in attenuating exercise-induced muscle damage would be interesting to know.

Nevertheless, from a performance nutrition standpoint, the research looks promising. It’s also been heavily advertised for athletes because it’s much cheaper than most commercial recovery drinks and supplements, which also helps reduce the risk of inadvertent doping. You can explore this topic further by reading the most recent review on cow’s milk as a recovery drink and its implications for athletes’ health and performance. But I would like to look closer at a glass of cow’s milk, through an integrative lens. This will be covered in Part 2 of this blog post.

References:

  1. Sayer et al (2018). Effect of drinking rate on retention of milk and water following exercise-induced dehydration [abstract]. ECSS.
  2. Rankin et al (2015). The effect of milk on the attenuation of exercise-induced muscle damage in males and females. Eur J Appl Physiol. 115(6):1245-61.
  3. Rankin et al (2018). Milk: An Effective Recovery Drink for Female Athletes. Nutrients. 10(2).
  4. Cockburn et al (2013). Effect of milk on team sport performance after exercise-induced muscle damage. Med Sci Sports Exerc. 45(8):1585-1592.