Measuring performance during the menstrual cycle: a model using oral contraceptives.

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Oral contraceptives (OCs) are widely used by female athletes.
• OCs create a consistent hormonal milieu, reducing variability in sex steroid levels.
• Understanding the impact of hormonal fluctuations on athletic performance is crucial.

Purpose of the Study:

• To investigate the relationship between steroid hormone concentrations during an oral contraceptive cycle and anaerobic performance.
• To assess if consistent hormone levels from a low-dose OC can be achieved.

Main Methods:

• Five female rowers using a low-dose OC were tested on anaerobic power and capacity.
• Tests were conducted at two phases of the OC cycle: high hormone (days 16-18) and low hormone (days 26-28).
• Blood samples analyzed for 17beta-estradiol (E2), progesterone (P4), glucose, triglyceride, and lactate.

Main Results:

• Anaerobic performance, including peak power output and 1000-m rowing time, improved during the low hormone phase (TDL).
• Glucose levels increased, while triglyceride levels decreased during the TDL phase.
• No significant differences in endogenous E2 and P4 concentrations were found between testing days or cycles.

Conclusions:

• Altered anaerobic performance was observed throughout the OC cycle, with improvements correlating with low estrogen and progestogen levels.
• The low-dose OC effectively standardized hormonal and metabolic variables, making it a suitable model for studying sex steroid effects.
• This research highlights the potential impact of hormonal fluctuations within OC cycles on female athletes' performance.