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B-61 Free Communication/Poster - Acute Exercise Wednesday, May 29, 2019, 1: 00 PM - 6: 00 PM Room: CC-Hall WA2

Menstrual Phase Differences In The Physiological Resolution Of Periodic Breath-holding During Heavy Intensity Fartlek Exercise

980 Board #214 May 29 2:00 PM - 3:30 PM

Brooke, Calaina1; Smith, Jordyn2; Belfry, Glen R.2

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Medicine & Science in Sports & Exercise: June 2019 - Volume 51 - Issue 6S - p 254
doi: 10.1249/01.mss.0000561270.19794.06
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PURPOSE: Fluctuations in ovarian hormones have been shown to affect the physiological responses to heavy-intensity exercise. These responses may be exacerbated during backstroke swimming during the underwater push-off phase where swimmers are required to perform breath holds (~5 s) while kicking to the surface. The purpose of this study was to compare the singular and combined effects of repeated cycles of 5 s breath holds (BH) and hi-power output (HPO), every 30 s, during heavy-intensity (HVY) exercise during follicular (FOL) and luteal (LUT) phases.

METHODS: Eight eumenorrheic women (22 ± 1 yr, VO2max 2.36 ± 0.4 L⋅min-1) performed four 6-min exercise bouts on a cycle ergometer at a power output of 50 % of the difference between vetilatory threshold and VO2max (α50%) in the FOL and LUT. A continuous HVY (CONT) with free breathing, and 3 intermittent conditions including, repeated cycles of 25 s free breathing and 5 s BH (BH), repeated cycles of 25s at α50% and 5s at peak aerobic power (HPO) and combining the BH and HPO (BH-HPO) perturbations were performed. Gas exchange and vastus lateralis deoxygenation (HHb) were recorded during all trials.

RESULTS: Mean Ventilation (VE) and total [hemoglobin] were higher in all conditions during LUT vs FOL (LUT 78.0 ± 10.7; FOL 75.1 ± 10.7 L⋅min-1 and FOL: 2.0 ± 2.2 μMol; LUT: 2.9 ± 1.9 μMol respectively p<0.05). Carbon dioxide production (VCO2) was higher during LUT BH-HPO (LUT: 2.41± 0.18 L⋅min-1; FOL: 2.19 ± 0.24 L⋅min-1p<0.05). Whereas %αHHb was greater during the 5s BH vs the 25s free-breathing period in both LUT (25s: 87 ± 9 %; 5s: 89 ± 8 % p<0.05) and FOL (25s: 86 ± 15 %; 5s: 89 ± 13 % p<0.05) phases. Further, %αHHb/%αVO2 was greater during BH (6%) and HPO-BH (7%) during the 5s BH vs the 25s free-breathing in both phases (FOL: 46.0 ± 18 %; LUT: 45 ± 14 % and FOL: 44 ± 18 %; LUT: 44 ± 15 % respectively p<0.05).

CONCLUSION: Low PO2 in the area of investigation (i.e. vastus lateralis) during heavy intensity exercise has been shown to increase CO2 transport by increasing the affinity of CO2 to Hb (Haldane effect). Moreover, the increased pulmonary diffusion capacity during the LUT phase suggested elsewhere would facilitate the observed increase in VCO2 and VE during the BH-HPO protocol of the present study. Finally, females show increased local muscle deoxygenation in both BH conditions during both the FOL and LUT phases.

Copyright © 2019 by the American College of Sports Medicine