No Differences in Lactate Threshold Across the Menstrual Cycle in Untrained Females

Area of Science:

• Exercise Physiology
• Sports Science
• Human Physiology

Background:

• Lactate Threshold (LT) is a key determinant of aerobic exercise performance, alongside maximal oxygen consumption (VO2max).
• Understanding factors influencing LT is crucial for optimizing training and performance in athletes and recreational exercisers.
• The potential impact of the menstrual cycle (MC) on physiological markers like LT in untrained females requires investigation.

Purpose of the Study:

• To investigate the influence of different menstrual cycle phases on lactate threshold (LT) in untrained females.
• To compare LT performance across the early follicular, ovulatory, and mid-luteal phases of the MC.
• To establish whether hormonal fluctuations during the MC alter exercise capacity at LT.

Main Methods:

• Eight untrained females and eight untrained males (control) underwent lactate threshold (LT) testing on a cycle ergometer.
• Tests were conducted across three MC phases for females: early follicular (menses), ovulatory, and mid-luteal.
• Blood lactate levels were measured at 3-minute intervals, with LT determined by visual inspection (LTvis) and fixed concentrations (LT2.0mmol, LT4.0mmol).

Main Results:

• No statistically significant differences in power at LT were observed across the MC phases for the female participants, irrespective of the determination method used (p>0.05).
• Male participants, serving as controls, also showed no significant differences in LT power across equivalent time intervals (p>0.05).
• A trend indicated higher power at LT in males compared to females across all LT determination methods.

Conclusions:

• The menstrual cycle phase does not appear to significantly influence lactate threshold power in untrained, naturally menstruating females.
• These findings suggest that hormonal variations during the MC do not substantially alter submaximal exercise capacity at LT in this population.
• Further research may explore trained populations or different exercise modalities to confirm these observations.