Do you drink cow’s milk as a part of your daily diet? As an endurance athlete, unless you are allergic or intolerant to milk – more on this below – perhaps you should consider it. I’m not talking here about just adding milk to tea, coffee or cereal but actually drinking a glass of it, particularly after a training session. There have been quite a few studies now on the effect that drinking milk has on post-exercise recovery, and I will explore some of these shortly.
First, here’s some nutritional information on milk.
- A 250ml glass contains about 8g of the proteins whey and casein, which help to repair muscle damage after running. Whey protein is high in the amino acid leucine, needed for muscle synthesis. 250ml also contains 12g of carbohydrate in the form of lactose, the naturally-occurring sugar. This makes milk a good recovery drink, especially if it is combined with some additional carbohydrate, eg from fruit or chocolate, to help replenish glycogen stores. Drinking milk also helps you to rehydrate and restore your body’s fluid balance, especially as it contains electrolytes: 250ml will provide you with 110mg of sodium and 40mg of potassium
- 250ml of cow’s milk also gives you 310mg of calcium (40% of your daily recommended intake), 27.5mg of magnesium and 2.5 IU of vitamin D, all nutrients needed to maintain strong bones.
- Milk is a good source of vitamin B12, which is required for red blood cell production and your body’s use of iron, both very important for athletes. Other nutrients in cow’s milk include vitamin B2, needed to convert food to energy, vitamin A which supports immune and digestive health and iodine, required for thyroid hormone function.
- Cow’s milk also contains the amino acid tryptophan. This is converted in your body to the neurotransmitter serotonin and the hormone melatonin, both of which play a role in encouraging sleep, another benefit for endurance athletes.
Most of the studies that have looked at the effect of consuming milk on endurance performance and recovery have used chocolate milk, which contains additional carbohydrate from sugar, and compared this with a regular energy drink containing carbohydrate but no protein. Karp et al (2006) 1 gave 9 endurance trained cyclists either chocolate milk or an energy drink after an interval workout and two hours of recovery. After a further two hours, the cyclists undertook a time trial to exhaustion at 70% VO2max. This was repeated on three occasions. Those who had the chocolate milk cycled 49% further than those who had the energy drink, suggesting improved recovery. In a similar study three years later on 9 trained cyclists, Thomas et al (2009) 2 examined the effects of three recovery drinks on endurance performance following a glycogen depleting exercise and a 4 hour recovery period. After consuming chocolate milk, subjects cycled 51% longer than after having an energy drink and also 43% longer than after having a fluid replacement drink, suggesting that chocolate milk is the most effective recovery aid.
In 2011, Ferguson-Stegall et al 3 found that drinking chocolate milk after cycling sessions for 4.5 weeks resulted in improved both VO2 max and body composition in 32 untrained subjects compared with a carbohydrate energy drink and placebo. This suggests benefits from drinking milk beyond just improved recovery. Another study performed the same year by the same research group 4 looked at the effect of chocolate milk versus carbohydrate only and placebo on recovery and subsequent endurance performance. 10 cyclists performed three trials, cycling 1.5 hours at VO2 max plus 10 minutes of intervals. They ingested one of the drinks immediately after exercise and again after two hours of recovery. After a further two hours recovery, they performed a 40km time trial. Biopsies were taken 0, 45 and 240 mins after the initial exercise session to assess protein synthesis rates. This showed a greater intracellular stimulus for protein synthesis in those who had consumed the chocolate milk than those who consumed the carbohydrate alone. The chocolate milk group also performed significantly better in the time trial. Finally, another study in 2012 by Lunn et al on runners 5 showed that those who consumed fat free chocolate milk rather than a carbohydrate drink after a 45 minute run and subsequent recovery, and then undertook a run to exhaustion saw greater muscle protein synthesis and better performance. There was no difference in muscle glycogen levels between the two groups.
The evidence certainly appears to strongly suggest that drinking milk with some additional carbohydrate after exercise is beneficial, particularly if you will be training again later in the day. So you could buy chocolate milk from a supermarket or convenience store as a recovery drink. This is likely to be cheaper than purchasing a specialist carbohydrate-protein recovery drink for endurance athletes and have a similar effect. Or you could drink milk and eat a banana to provide some extra carbohydrate to further replenish glycogen stores. Or – my personal favourite – you could make your own milk-based recovery drink by blending frozen berries, a banana, a tablespoon of nut butter and 250 ml of milk. Delicious!
But what if you can’t drink cow’s milk? Its proteins, whey and casein, are one of the most common foods for people to be allergic to. Other people are lactose intolerant, meaning that they do not produce sufficient amounts of the enzyme lactase to digest lactose, the sugar found in milk. Drinking cow’s milk results in unpleasant digestive symptoms such as diarrhoea, bloating and abdominal discomfort. Other health issues such as rhinitis (runny nose), eczema and hives have also been linked to drinking cow’s milk.
There are many alternatives available: soya milk, coconut milk, almond milk and rice milk, for example. But do check the protein content. If this is shown as less than 3g per 100ml, I suggest adding a non-dairy protein powder such as soya, rice, pea or hemp to your post-exercise recovery drink. You should also check that your choice of non-dairy milk has been fortified with the nutrients calcium and vitamin B12. If you are lactose intolerant, it may be worth trying the Lactofree ® brand www.lactofree.co.uk. This is normal cow’s milk where half the lactose has been filtered out and the digestive enzyme lactase added to improve digestion. Please note that this product is not suitable for those with milk allergies. If you seem to experience unpleasant symptoms after drinking milk but have not been diagnosed as allergic to milk or lactose intolerant, it may be worth trying A2 Milk http://www.a2milk.co.uk/ which contains milk from cows that only produce the A2 casein protein, not the A1 casein protein found in most commercially available milk. A 2014 preliminary study 6 found that improved digestive symptoms were experienced by those consuming A2 Milk, which is becoming more widely available in the UK and is already very popular in Australia.
So in conclusion, the research suggests that drinking milk plus some additional carbohydrate improves recovery after exercise as shown by performance in a subsequent session. If you can tolerate milk, I do suggest including it in your post-training routine, and allow yourself to benefit from its nutritional profile as well as the recovery benefits. If milk simply does not agree with you, there are alternatives to explore, but take care to look at the nutritional content of non-dairy ‘milks’ which may not contain much protein or calcium or any vitamin B12 unless fortified.
Jo Scott-Dalgleish BSc (Hons) is a BANT Registered Nutritionist, writing and giving talks about nutrition for endurance sport. Based in London, she also works as a Registered Nutritional Therapist, conducting one–to–one consultations with triathletes, distance runners and cyclists to help them eat well, be healthy and perform better through the creation of an individual nutritional plan. To learn more about these consultations, please visit www.nutritionforendurancesports.co.uk
1 Karp et al. Chocolate milk as a post-exercise recovery aid. Int J Sport Nutr Exerc Metab. 2006. Feb; 16(1):78-91
2 Thomas K, Morris P, Stevenson E. Improved endurance capacity following chocolate milk consumption compared with two commercially available sports drinks. Appl Physiol Nutr Metab. 2009. Feb; 34(1): 78-82.
3 Ferguson-Stegall et al. Aerobic training adaptations are increased by post-exercise carbohydrate-protein supplementation. J Nutr Metab. 2011. E-pub http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136187/
4 Ferguson-Stegall et al. Post-exercise carbohydrate-protein supplementation improves subsequent exercise performance and intracellular signalling for protein synthesis. J Strength Cond Res. 2011. May; 25(5):1201-24.
5 Lunn et al. Chocolate milk and endurance exercise recovery: protein balance, glycogen and performance. Med Sci Spots Exerc 2012. Apr; 44(4): 682-91.
6 Ho et al. Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study. Eur J Clin Nutr. 2014. Sept; 68(9):994-1000.