Effects of increased exercise intensity on the heart’s stroke volume in elite female cross country skiers
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Purpose: Previous research has shown that endurance trained (ET) males increase stroke volume (SV) progressively with increasing exercise intensity up to maximal oxygen uptake (VO2max). However, few investigations have included ET female subjects. The purpose of this study was to investigate the SV response to increased exercise intensity in ET women. Method: Thirteen elite female cross country skiers were tested for VO2max using the Metamax II. Cardiac output (Q) was measured at rest, 40%, 60%, 80% and 100 % of VO2max, using the single breath acetylene rebreathing method. SV was calculated by dividing Q with HR. Results: Mean VO2max was 67.1 ± 6.1 ml∙kg‐1∙min‐1, 4.072 ± 0.219 L∙min‐1. Mean SVrest was 72.3 ± 12.6 mL∙beat‐1 and mean SVmax was 129.1 ± 16.3 mL∙beat‐1. The SV increased from rest to 40% of VO2max, plataued from 40‐80 % of VO2max and then increased from 80‐100% of VO2max (P<0.05). Qrest was 6.6 ± 0.6 L∙min‐1 and Qmax was 23.5 ± 2.5 L∙min‐1. Q increased progressively with increasing exercise intensity up to VO2max (P<0.05). Conclusion: The SV of the present elite female cross country skiers increased from rest to 40% of VO2max, plataued from 40‐80 % of VO2max and then made a secondary increase from 80‐100% of VO2max.The hypothesis of a progressive increase in SV with increased exercise intensity, as observed in ET men, was thus rejected.