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  • Author: Anthony C Hackney x
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Summary

Study aim: Evidence supports female sex hormones have an influencing effect on amultitude of physiological and psychological systems related to exercise. Little is known, however, whether is effect persist into the recovery from exercise. Our objective was to examine aspects of muscle damage/inflammation process during recovery in healthy, exercise-trained women following endurance activity at the mid-follicular (MF; low sex hormone level) and mid-luteal (ML; elevated sex hormone levels) phases of their menstrual cycle.

Material and methods: The MF and ML exercise sessions consisted of running for 90 minutes at 70% VO2max on atreadmill in a controlled laboratory environment. Menstrual cycle phase was hormonally confirmed, diet and physical activity was control throughout the study. Outcome measures were: blood creatine kinase (CK) and interleukin-6 (IL-6) assessed at immediate-post exercise (IP), 24-hour and 72-hour into recovery. Statistics involved ANOVA procedures.

Results: At 24-hours and 72-hour into recovery CK activity was greater in MF than ML (p < 0.05) while for IL-6 at IP, 24-hour and 72-hour responses were significantly greater at MF than at ML (p < 0.05).

Conclusions: Amore robust recovery CK and IL-6 response occur in the MF of the menstrual cycle when female sex hormones are reduced. This finding suggests female sex hormone changes due to menstrual cycle phase affect the physiologic responses during the extended recovery period from intensive exercise in eumenorrheic women.

Abstract

This study aimed to compare selected hormonal responses to a single session of high intensity interval training performed with an increased fraction of inspired oxygen (hyperoxia) and under normoxic conditions. Twelve recreationally trained men (age 24 ± 3 years) performed two sessions of high intensity interval training on a cycle ergometer, in randomized order with hyperoxia (4 L·min-1 with a flowrate of 94% O2) and normoxia. Each session consisted of 5 intervals of 3 minutes at 85% of the maximal power output, interspersed by 2 min at 40% of the maximal power output. Serum cortisol, prolactin and vascular endothelial growth factor (VEGF) were assessed both before and immediately after each high intensity interval training session. Statistically significant differences in cortisol were found between hyperoxic and normoxic conditions (p = 0.011), with a significant increase in hyperoxia (61.4 ± 73.2%, p = 0.013, ES = -1.03), but not in normoxia (-1.3 ± 33.5%, p > 0.05, ES = 0.1). Prolactin increased similarly in both hyperoxia (118.1 ± 145.1%, p = 0.019, ES = -0.99) and normoxia (62.14 ± 75.43%, p = 0.005, ES = -0.5). VEGF was not statistically altered in either of the conditions. Our findings indicate that a single session of high intensity interval training in low-dose hyperoxia significantly increased cortisol concentrations in recreationally trained individuals compared to normoxia, while the difference was smaller in prolactin and diminished in VEGF concentrations.