Cereal and non-fat milk support muscle recovery after endurance exercise

Posted on June 09th, 2009 in Diet, Drink, Exercise, Food, Science, Training

cereal

It’s something I know I’m guilty of. Come back from a long run, get in the bath and forget all about eating and refuelling.

Endurance exercise affects skeletal muscle by reducing energy stores and increasing muscle protein breakdown. So after exercise it’s important to refuel and replace the bodies main source of stored energy, glycogen. During endurance exercise glycogen stored in skeletal muscle is reduced which can limit exercise duration and intensity. Therefore, it is important to replenishing these energy stores before your next training session or competition.

In addition, muscle protein breakdown is continuously occurring, even at rest, releasing amino acids to be used for protein synthesis. However, protein synthesis is stimulated by exercise and muscle protein breakdown is increased. So it’s important that consumption of food must offset breakdown to create a positive net muscle protein balance.

Taking these two facts into account suggests that the ideal recovery food must contain both carbohydrate and protein to provide substrate for glycogen synthesis and achieve net protein balance. But what’s the best fuel to use?

Commercial carbohydrate-electrolyte sports drinks are available for post exercise recovery, but how do they compare with eating regular food. A group of researchers from the University Texas have compared the effects of ingesting regular cereal and non-fat milk, with drinking carbohydrate-electrolyte sports drink immediately following endurance exercise, investigating muscle glycogen synthesis and the regulation of proteins controlling protein synthesis.

Whilst many studies use untrained subjects or exercise to exhaustion Dr Kammer’s study a more realistic training scenario. The study published in Journal of the International Society of Sports Nutrition involved trained cyclists and triathletes who completed 2 hours of cycling at 60-65% of their predetermined VO₂MAX (this is the maximum volume of oxygen that can be used during one minute of maximal exhaustive exercise).

Immediately after exercise the subjects consumed either a drink (containing 78.5 g carbohydrate) or cereal (77 g carbohydrate, 19.5 g protein and 2.7 g fat). The researchers found that after 60 min following refuelling with either the drink or cereal:

blood glucose levels was similar between both drink and cereal;
significant changes did occur in glycogen levels following both methods of refuelling;
glycogen and muscle proteins were not different between treatments.

BUT

after cereal blood insulin levels was significantly higher;
after cereal blood lactate was significantly lower;
only cereal significantly affected glycogen synthase.

The researchers were able to conclude that while the drink provided carbohydrate, only the cereal and milk provided carbohydrate and essential amino acids necessary to support both glycogen and protein synthesis. This is due to the cereal option also providing easily digestible and quality protein in the milk. The benefits of the findings to the everyday athlete is that cereal and non-fat milk provide a less expensive whole food option as compared to sports drinks.

Whilst Dr Kammer and colleagues now suggest cereal and non-fat milk as a potential option for athletes who refuel at home, the down side was that to eat the necessary amounts of carbohydrates required consuming the equivalent of two potions according to the recommended sizes on the box.

So now we know what to eat, I just need to schedule time for it straight after training, before I head for the bath.