Power training: research shows increasing protein intake will improve performance

Power Athlete's Diet:

There are many protein and amino acid supplements on the market, but how do you know if you need them in addition to your normal diet? New research suggests that boosting protein intake could be beneficial to athletes.

In a recent study, competitive sprinters and jumpers completed two sets of two testing sessions, interspersed by a five-week training period, while the researchers measured the effects of the activity on a number of blood variables.

The first test was a short run session, comprising three sets of 4x60m sprints, two minutes between reps and six minutes between sets; the second test – performed the next day – was a long run session comprising short 20s treadmill sprints to exhaustion. The speed of the treadmill was increased slightly between each rep, separated by 100s rest.

The athletes’ blood levels of amino acids, testosterone, growth hormone and cortisol were measured on the morning of the tests (fasting level), then 10 minutes before and 10 minutes after the running workouts.

They then completed five weeks of typical off-season training, comprising sprints, speed endurance, plyometrics and free weights sessions, before repeating both testing sessions.

Throughout the study period, the athletes consumed their normal self-selected diets, which were made up, on average, of 53% carbohydrates, 32% fat and 15% protein.

Analysis of the athletes’ blood tests showed that fasting levels of amino acids were about 20% lower after the five-week training period than they had been before. By contrast, resting testosterone had increased by about 25%. And while the short run session led to reduced levels of certain amino acids – asparagine, valine and taurine – the long run session produced no significant changes.

The reduction in fasting levels of amino acids after the training period suggests that the athletes’ protein intake was inadequate to cope with the demands of power training, when the body increases its rate of protein synthesis by plundering its pool of free amino acids. The rise in testosterone and relatively low levels of cortisol after the training period showed that the athletes were in a healthy anabolic state – i.e. their bodies were ready to recover from training and build muscle. However, the implication is that they might have reaped greater benefits from their training programme if they had increased the level of ‘building materials’ (amino acids) in their diets and that a dietary intake of 15% protein (or 1.25g/kg) is too low for power athletes performing quality training.

The researchers suggest that 1.7g/kg of body weight might be more appropriate for maximising training benefits. Ideally power athletes should focus on low-fat protein foods, such as cottage cheese, turkey, egg whites, soya products, beans and pulses. This research also supports the use of protein supplements during exercise sessions; a practical method would be to mix them with carbohydrate and electrolytes in a drink.

Journal of Strength and Conditioning Research, 16(2), 390-398

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