Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Kinesiology

Supervisor

Belfry, Glen

Abstract

Fifteen females participated in an incremental ramp (RAMP) and severe intensity (SI) exercise protocol, both to volitional fatigue, during their follicular (FOL) and their luteal (LUT) phases of their menstrual cycle. Oxygen uptake (VO2), carbon dioxide production (VCO2), ventilation (VE), arterialized blood lactate [La-], and muscle deoxygenation (Δ[HHb]) were measured during testing. Throughout the duration of the RAMP (20-100%), VO2 was higher during the FOL phase (p=0.000850). However, VCO2, VE, La- and Δ[HHb] were unchanged between phases. For the SI (20-100%) protocol, there were no significant changes observed between phases for VO2, VCO2, VE, La-, or Δ[HHb]. Correlations between power output and VO2 during RAMP, in particular, were very high (0.90), suggesting, as others have suggested, that individual differences in menstrual phases symptoms may affect performance both positively and negatively in eumenorrheic females, despite no changes in the cardiorespiratory responses to maximal effort exercise bouts.

Summary for Lay Audience

Whether one is exercising for themself, or is participating in a sport, multiple human body systems are influencing the way in which one performs. Major body systems contributing to controlling physical performance shared between males and females, include the cardiovascular and respiratory systems. These are responsible for the transport of oxygen to the working muscles and acquiring oxygen from the atmosphere for use. However, in females, the reproductive system is a unique sex specific system that impacts hormones in the body that may influence exercise performance throughout the menstrual cycle. This is a monthly cycle that results in hormonal changes that may have both physical and psychological impacts in females, that may in turn affect exercise performance. However, research in this area has been limited. This research study investigated the responses of several cardiorespiratory variables during the menstrual cycle during high-intensity exercise. Each participant underwent a progressive cycle exercise test, beginning at a low resistance to high resistance, till the participants were unable to continue due to task failure. This was followed five minutes later, by a high-intensity bike exercise at a constant load, till volitional fatigue. These tests were performed at the onset of their period, and again approximately two weeks later. Observations showed that the body’s use of oxygen was slightly higher during the increasing work rate test during their periods, but there were no changes in any other variables. However, there were several participants that either performed poorly, or very well on the exercise tests. Previous research has suggested emotional or menstrual cycle symptoms may have caused these differences. Our results suggest that despite little physiological differences seen during this study throughout their monthly cycle, performance may be impacted by other, perhaps emotional symptoms that females experience during their monthly cycle.

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