Beyond the Zone: Protein Needs of Active Individuals

Abstract

There has been debate among athletes and nutritionists regarding dietary protein needs for centuries. Although contrary to traditional belief, recent scientific information collected on physically active individuals tends to indicate that regular exercise increases daily protein requirements; however, the precise details remain to be worked out. Based on laboratory measures, daily protein requirements are increased by perhaps as much as 100% vs. recommendations for sedentary individuals (1.6–1.8 vs. 0.8 g/kg). Yet even these intakes are much less than those reported by most athletes. This may mean that actual requirements are below what is needed to optimize athletic performance, and so the debate continues. Numerous interacting factors including energy intake, carbohydrate availability, exercise intensity, duration and type, dietary protein quality, training history, gender, age, timing of nutrient intake and the like make this topic extremely complex. Many questions remain to be resolved. At the present time, substantial data indicate that the current recommended protein intake should be adjusted upward for those who are physically active, especially in populations whose needs are elevated for other reasons, e.g., growing individuals, dieters, vegetarians, individuals with muscle disease-induced weakness and the elderly. For these latter groups, specific supplementation may be appropriate, but for most North Americans who consume a varied diet, including complete protein foods (meat, eggs, fish and dairy products), and sufficient energy the increased protein needs induced by a regular exercise program can be met in one’s diet.

• amino acids
• energy
• physically active
• exercise performance
• athletes

Key teaching points:

• Dietary protein needs for physically active individuals have been controversial for many years.

• Generally, athletes have felt their needs are substantially greater than the recommendation from scientists - both opinions could be correct as the latter is based on data from essentially sedentary subjects.

• Recent scientific study suggests a variety of factors need to be considered when determining protein requirements, including but probably not limited to total energy intake, carbohydrate availability, exercise intensity, exercise duration, exercise type, dietary protein quality, training history, gender, age and timing of nutrient intake.

• These studies indicate that for physically active individuals daily protein intake needs could be as high as 1.6–1.8 g/kg (about twice the current recommendation).

• Despite these increased protein needs, assuming energy intake is sufficient to match the additional expenditures of training and competition (which can be excessive), special protein supplementation is unnecessary for most who consume a varied diet containing complete protein foods (meat, fish, eggs and dairy products).

• Those at greatest risk of consuming insufficient protein are those whose lifestyle combines other factors known to increase protein needs with a regular exercise program, e.g., those with insufficient energy intake (dieters), growing individuals, vegetarians, the elderly, those with muscle diseases and so on.

Key teaching points:

• Dietary protein needs for physically active individuals have been controversial for many years.

• Generally, athletes have felt their needs are substantially greater than the recommendation from scientists - both opinions could be correct as the latter is based on data from essentially sedentary subjects.

• Recent scientific study suggests a variety of factors need to be considered when determining protein requirements, including but probably not limited to total energy intake, carbohydrate availability, exercise intensity, exercise duration, exercise type, dietary protein quality, training history, gender, age and timing of nutrient intake.

• These studies indicate that for physically active individuals daily protein intake needs could be as high as 1.6–1.8 g/kg (about twice the current recommendation).

• Despite these increased protein needs, assuming energy intake is sufficient to match the additional expenditures of training and competition (which can be excessive), special protein supplementation is unnecessary for most who consume a varied diet containing complete protein foods (meat, fish, eggs and dairy products).

• Those at greatest risk of consuming insufficient protein are those whose lifestyle combines other factors known to increase protein needs with a regular exercise program, e.g., those with insufficient energy intake (dieters), growing individuals, vegetarians, the elderly, those with muscle diseases and so on.

Notes

An honorarium was provided for support of this manuscript by the Egg Nutrition Center.

Presented, in part, at a meeting sponsored by the American Egg Board and Egg Nutrition Center held at Amelia Island, FL on February 25–27, 2000.