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Four interesting aspects of nutrition are placed under the microscope. What are the consequences for female athletes?

This article is presented by the Swiss Sports Nutrition Society

The International Olympic Committee set itself the goal of achieving a female participation of almost 50% at the 2021 Olympic Games in Tokyo and speaks of the first «gender-balanced Olympic Games in history». But what do we in the sports and nutrition sciences know about training, menstrual cycles, and nutrition in women's sports? Only a small proportion of the scientific studies were conducted with female study participants. The reasons for this are multifaceted: menstrual cycle-dependent factors, lower power density, fewer female study participants. At present, it is therefore only possible to formulate evidence-based recommendations in very few disciplines. Recommendations from studies conducted with men frequently serve as the basis for both sexes. This article discusses four aspects of nutrition for female athletes.

Sufficient energy supply

Due to their smaller size, lower weight and lower proportion of fat-free mass, the energy requirement of female athletes is lower than that of their male colleagues. In order to be healthy and reproductive as well as achieve optimal training effects and performance, it is important for female athletes to have an energy supply that sufficiently meets their needs.

Around 22-58% of athletes do not cover their energy requirements, with female athletes being far more affected than male athletes. In order to prevent this, it is recommended that female athletes receive individual assistance and support in terms of their sport-specific nutrition. It is also important that trainers and mentors are aware of this problem and how to deal with it. The influence of social media or the pressure to conform to a certain body image should also not be overlooked. Both have an impact on physical and mental health.

Carbohydrates in sports

Until a larger number of new studies with female athletes are available that examine the intake of carbohydrates during an athletic performance depending on the scope of training and menstrual cycle, similar nutritional recommendations regarding the intake of carbohydrates apply to female athletes as well as to male athletes. It appears unclear as to what effect «Train Low», i.e., training with depleted glycogen reserves, can have on the performance capability of women as well as their health and training adaptation. Therefore, such training methods should still be used with caution at present.

Do women need less protein?

Due to an increased protein turnover, the recommended intake of protein for sports (1.2 to 2.0 g/kg/day) is much higher than that recommended for the «normal» population (0.8 g/kg/day). However, these sport-specific protein recommendations are mainly based on studies conducted with male study participants. It is assumed that female athletes with a normal menstrual cycle require more protein towards the end of the cycle, when the estrogen and progesterone levels are high. This can be seen by an increase in nitrogen excretion as well as protein breakdown. The extent to which this can have an influence on the intake of protein needs to be investigated in more detail in future before any cycle-dependent recommendations can be made.

Fluid balance in the female body

During the menstrual cycle, the thirst sensation and water balance are regulated in the body. In the process, water retention in the body increases due to the concentration of estrogen and the rising level of progesterone (second half of the cycle). The use of compression stockings, especially in the second half of the cycle, can help to prevent water retention in the legs. The female body is reportedly more prone to dehydration in the second phase of the cycle. And it is well known that dehydration has a negative impact on the endurance performance capability. However, to what extent this will change the fluid recommendations for female athletes has not yet been clarified.

Conclusion

Although some studies already describe the effects of the menstrual cycle on physiological parameters as well as the differences between men and women, there is generally little scientific evidence available to make specific recommendations. In general, female athletes are advised to work with a sports nutrition specialist to tailor their diet to their individual needs. Women-specific issues should also be addressed. It is also worth clarifying whether the female athlete uses hormonal contraception, whether the menstrual cycle is regular and which symptoms can be observed. All these facts help to optimise their nutrition, training, and health.