There are sex differences in the cardiorespiratory and hemodynamic response to exercise due to inherent differences in heart size, blood volume, and hemoglobin mass that elicit a higher VO2max in men versus women. These alterations in cardiac structure and function may mediate changes in VO2max per the Fick Equation. However, existing data are inconclusive on whether sex differences in training responsiveness exist. PURPOSE: The purpose of this study is to investigate potential sex differences in the hemodynamic response to HIIE. If men and women reveal discrepant cardiovascular responses to HIIE, this may partially mediate sex differences in VO2max response to HIIT reported. METHODS: Subjects were habitually active men (n=7, age 28 ± 4 yr) and women (n=7, age 23 ± 3 yr). In this randomized, within-subjects crossover design, VO2max was initially tested followed by three subsequent sessions consisting of different HIIE paradigms. RESULTS: Results show a main effect of sex in peak absolute VO24x4 VO210x1 and VO2REHIT (p = 0.022, p = 0.009 and p = 0.005 respectively) and a significant difference in peak VO2 (%VO2max) between REHIT and 4x4 (p = 0.008) and 10x1 (p = 0.001). Results show a main effect of sex in peak absolute SV4x4 and SVREHIT (p = 0.008 and p = 0.006) and a significant difference in peak absolute SV and SV (%SVmax) between REHIT and 4x4 (p = 0.002 and p = 0.002). Results also show a main effect of sex in peak absolute COREHIT (p = 0.042) and a main effect of protocol in peak absolute and relative CO between REHIT and 4x4 (p = 0.022 and p = 0.017). Results show a main effect of sex in mean absolute VO24x4 VO210x1 and VO2REHIT (p = 0.013, p = 0.014 and p = 0.006) and a significant difference in mean absolute VO2 between REHIT and 4x4 (p = 0.018) and 10x1 (p = 0.019). A similar significant difference between REHIT and 4x4, and 10x1 is found when expressed as %VO2max (p = 0.016 and p = 0.010). Results show men reveal higher mean SV4x4, SV10x1 and SVREHIT values than women (p = 0.004, p = 0.019, p = 0.045) and higher CO10x1 values than women (p = 0.046). CONCLUSION: Other than the well-known differences in SV and CO between men and women, our data show no sex differences in acute hemodynamic response to three unique regimens of HIIE. This suggests that reported sex differences in the VO2max adaptation to exercise are not due to a difference in acute cardiac response.
Coe, Leah N.
"Sex Differences in Hemodynamic Response to High Intensity Interval Exercise (HIIE),"
International Journal of Exercise Science: Conference Proceedings: Vol. 14:
2, Article 8.
Available at: https://digitalcommons.wku.edu/ijesab/vol14/iss2/8