Menstrual cycle considerations in formulating for female athletes

Let’s get one thing clear—a HUGE issue exists in nutrition research: Scientists don’t like to use females in their research studies because it’s more difficult.

The reason? It’s much more challenging to determine if a particular nutrition intervention is having a true effect, or if the effect observed is a function of hormonal fluctuations.

This hindrance has had a profound trickle-down effect into the nutritional recommendations made in the public sphere. The research comes from a predominantly male population, and the typical recommendations from that research make the completely erroneous assumption that females are simply small males.

In good news, some researchers have realized the mistake and have started to redo the old stuff. Unsurprisingly, females respond QUITE differently than males.

Recent literature suggests key supplements have shown to be uniquely beneficial to females. A basic overview of the menstrual cycle can be helpful in understanding some of the physiological patterns at play.

The menstrual cycle can be broken up into three phases: early follicular phase, late follicular phase and luteal phase.¹

The early follicular phase corresponds with the onset of menstruation and is characterized by hormones being at their lowest levels. This phase typically lasts approximately five days.

The late follicular phase is characterized by a rise in the various hormone levels (estrogen, follicle-stimulating hormone and luteinizing hormone) and lasts until about day 14. The rise in hormones causes ovulation to occur.

The luteal phase begins after ovulation. Luteinizing hormone and follicle-stimulating hormone return to normal levels, while estrogen and progesterone continue to rise to ready the body for possible pregnancy. If no pregnancy occurs, hormone levels return to normal and menstruation begins.

The different phases correspond with unique metabolic shifts. Relevant to this discussion, the follicular phase corresponds with increased carbohydrate oxidation rates, while the luteal phase corresponds with increased protein oxidation rates and core body temperature. Again, awareness of these phases can play an important role in developing effective products for female athletes.

Hydration beverages

Core body temperature is elevated in females during the luteal phase. As such, onset of sweating occurs sooner and increased risk for overheating occurs.^2,3,4 Fluids become increasingly important during times of exercise, and females should take extra care that their hydration patterns are in agreement with sports nutrition guidelines.

As a quick rule, females should consume half their bodyweight (in pounds) in fluid ounces per day and add in sweat losses. For example, a 140-pound female should consume 70 oz. of water per day as a minimum.

Carbohydrate supplements

During the follicular phase, carbohydrate oxidation is higher. This phase is perfect for glycolytic exercises (like high-intensity circuits) that burn a lot of carbohydrates. Carbohydrate supplements can be useful during this time if carbohydrate needs are not otherwise being met.⁵

Editor’s note: The full version of this article—including more guidance about supplement ingredients ranging protein and omega-3s to creatine, caffeine, vitamins and minerals, among others—appears in the “Natural women’s health solutions for every stage” digital magazine. Click the link to access it and select “Feeding the unique phases of the female athlete” from the TOC.

Casey Thomas, RDN, owns Gamer Diet and works as a performance dietitian, writer and instructor. His unique research background has allowed him to implement protocols that have facilitated significant improvements in body composition, health and performance among athletes. Thomas has consulted with professional athletes and Olympians, esports programs, universities and businesses looking to gain a performance edge. Currently he’s focused on esports, working to bring high-level, research-backed performance nutrition to the gaming world.

References

1 Wohlgemuth KJ et al. “Sex differences and considerations for female specific nutritional strategies: a narrative review.” J Int Soc Sports Nutr. 2021;18(27).

2 Pivarnik JM et al. “Menstrual cycle phase affects temperature regulation during endurance exercise.” J Appl Physiol. 1992;72(2):543-548.

3 Grucza R et al. “Influence of the menstrual cycle and oral contraceptives on thermoregulatory responses to exercise in young women.” Eur J Appl Physiol Occup Physiol. 1993;67(3):279-285.

4 Inoue Y et al. “Sex- and menstrual cycle-related differences in sweating and cutaneous blood flow in response to passive heat exposure.” Eur J Appl Physiol. 2005;94:323-332.

5 Oosthuyse T and Bosch AN. “The effect of the menstrual cycle on exercise metabolism: implications for exercise performance in eumenorrhoeic women.” Sports Med. 2010;40:207-227.