Risk of consuming inadequate amounts of protein

Although many athletes focus on protein, some do not consume enough protein. This problem is common among endurance athletes, such as runners. These athletes focus not on building muscle mass, but on consuming excess calories and gaining weight. The most common North American diets, which are sources of protein, are often high in fat, which can be replaced by carbohydrates. Inadequate protein can put an athlete at risk of losing muscle mass. Inadequate protein intake means a lack of amino acids for tissue repair and synthesis, and puts the athlete at risk for injury. Chronic fatigue in these athletes also indicates muscle weakness.

Triad of female athletes

The triad of female athletes is characterized primarily by inadequate caloric intake followed by menstrual irregularities (amenorrhea) and finally osteoporosis. It has been suggested that inadequate protein intake may be associated with the occurrence of amenorrhea. It has been shown that menstrual irregularities and estrogen deficiency lead to inadequate calcium accumulation and, consequently, to bone defects including fractures and osteoporosis.

Clark et al. found that amenorrhoeic female runners consumed 300-500 kcal/day less than female athletes with normal menstrual cycles. Helson et al. showed that 82% of amenorrhoeic women had protein intakes below the RDI, while only 35% of subjects with normal menstrual cycles had protein intakes below the RDI. Calcium intake did not differ between the two groups. The diets of female runners, dancers, and gymnasts have been shown to be inadequate in many nutrients, including total calories and protein. The relationship between protein intake and menstrual function is not yet completely clear, but there is a risk of amenorrhea for athletes with insufficient protein intake. It is also interesting to know whether protein quality is related to the risk of amenorrhea.

Sample menu illustrating protein intake from food

• Vegetarians: Protein Quality

Protein utilization is more efficient when its quality is high. FAO/WHO use egg white as a standard against which the quality of other proteins is compared.

A diet without animal products calls into question the synthesis of all amino acids. The less animal protein in an athlete's diet, the more vegetable protein is needed to meet the needs for amino acids. Soy products are an exception. To assess protein quality, FAO/WHO use the "amino acid assessment" as an alternative to the older method - the protein efficiency ratio (PER). As an assessment, they use hydrolysates and concentrates of soy protein, equivalent to animal proteins in their ability to meet the long-term needs of children for amino acids.

Vegetarians who include dairy products, eggs, and soy products in their diets should have no difficulty meeting their amino acid and total protein needs.

• Women who care about their body weight

Many women consume inadequate amounts of protein to reduce caloric intake. Protein utilization decreases as energy levels fall below energy expenditure.

• Pregnant sportswomen

During pregnancy, protein requirements increase. Pregnant women require about 60 g of protein per day, compared to 45 g per day for non-pregnant women. Research on exercise during pregnancy is relatively new. Many athletes train throughout their pregnancy. The intensity and duration of the training, as well as its effect on pregnancy, depend on many factors, including the woman’s level of fitness. A pregnant woman’s exercise program should be discussed with her physician. Protein requirements for an exercising pregnant woman have not been established. Safe recommendations range from 1.0 to 1.4 g per kg of body weight.

• Older people

Protein utilization changes with age. As people become less active with age, their protein requirements require further study.

• Diabetes

Diabetics are advised not to exceed the RDA for protein. Diabetics who exercise should meet their increased protein needs as long as there are no kidney problems and consult their physician regularly.

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