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By Don Heatrick
In this article I'm going to look at supporting your training efforts with adequate protein and carbohydrate intake. I've already discussed sources of these two macro nutrients in previous articles (please visit here for detail), now lets look at quantities required and timing.
Carbohydrates are the most important energy source for our training sessions, and protein is required for rebuilding and remodelling muscle tissue. A consequence of intense training is the breakdown of muscle protein and a loss of muscle tissue. This is bad news not only for those wishing to build muscle but also for those trying to lose fat – as muscle burns calories, the more you have the easier you'll lose fat. So nutritional protein must be made available to repair this breakdown and even sustain increased muscle mass. Before all the ladies and endurance athletes reading this tune out, lean, toned muscles require protein too – not just bulky, body building ones.
Protein Intake and Nitrogen Balance
Sports scientists measure nitrogen balance to determine if your body is losing or gaining protein. Your body is in nitrogen balance when the amount of protein eaten in your food equals the amount lost in faeces, urine and sweat. You should aim for a positive nitrogen balance, where more protein is ingested than is lost.
The World Health Organisation recommends that a sedentary person should consume around 0.8g/kg of body mass per day to achieve nitrogen balance. Whereas athletes engaged in resistance training should take at least 1.8g/kg body mass per day, and endurance trained athletes around 1.5 g/kg per day. This is because the protein turnover is greater when exercise is undertaken, especially resistance exercise.
The following graph shows the effect of a period of training for a group of sedentary individuals consuming 1g/kg of body mass per day, resulting in a negative nitrogen balance, i.e. insufficient protein to repair damage to muscles! Quite simply, if you're training you need more protein than your sedentary counterparts.
What and When
A number of studies have shown that nutritional intervention can reduce the breakdown of muscle protein following exercise and promote protein synthesis. These interventions include consuming carbohydrates and protein before exercise, consuming carbohydrates during exercise and consuming carbohydrates and protein after exercise. Carbohydrate intake is relevant as it helps spare muscle protein by provoking the release of insulin, which is an anabolic hormone stimulating protein synthesis. The only time carbohydrates may be avoided is when there's a need to reduce body fat – since excess carbohydrates are stored as fat.
So here's a general summary of the recommendations:
1) Ensure adequate amounts of daily carbohydrate are eaten i.e. 6-8 g/kg body mass per day when training intensely.
2) Ensure low/medium GI carbohydrate (1g/kg body mass) and up to 25g of protein (containing essential amino acids) are ingested 60 minutes before intense training.
3) For training sessions lasting less than 60 minutes it's unnecessary to take on carbohydrates during training.
4) Ingest high GI carbohydrates (1-2g/kg body mass) and protein in a 3:1 ratio in the hour after training.
5) Ensure protein intake levels are not lower than 1.5-1.8g/kg body mass a day.
Remember that all of these recommendations should also fit within your overall body mass goal, that is to either maintain, reduce or increase body mass. Daily calories should match your expenditure to maintain weight, be 500 kcals less to lose fat (while maintaining muscle mass) or 500 kcals higher than required to increase muscle mass while avoiding putting on fat.
Successfully apply these recommendations and your recovery and work capacity will sky rocket, and you'll progress swiftly toward your goals.
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