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Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children
Medicine & Science in Sports & Exercise, Volume: 47, Issue: 9, Pages: 1877 - 1884
Swansea University Author: Melitta McNarry
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PURPOSE:To characterise changes in deoxyhemoglobin ([HHb]) response dynamics in boys and girls during ramp incremental exercise to investigate whether the reduced peak oxygen uptake (peakV˙O2) in girls is associated with a poorer matching of muscle O2 delivery to muscle O2 utilisation, as evidenced...
|Published in:||Medicine & Science in Sports & Exercise|
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PURPOSE:To characterise changes in deoxyhemoglobin ([HHb]) response dynamics in boys and girls during ramp incremental exercise to investigate whether the reduced peak oxygen uptake (peakV˙O2) in girls is associated with a poorer matching of muscle O2 delivery to muscle O2 utilisation, as evidenced by a more rapid increase in [HHb].METHODS:52 children (31 boys, 9.9 ± 0.6 years, 1.38 ± 0.07 m, 31.70 ± 5.78 kg) completed ramp incremental exercise on a cycle ergometer during which pulmonary gas exchange and muscle oxygenation parameters were measured.RESULTS:When muscle [HHb] was expressed against absolute work rate and V˙O2, girls had an earlier change in [HHb] as evidenced by the lower c/d parameter (Girls: 54 ± 20 W vs Boys: 67 ± 19 W, P=0.023; Girls: 0.82 ± 0.28 L·min vs. Boys: 0.95 ± 0.19 L·min, P=0.055) and plateau (Girls: 85 ± 12 W vs. Boys: 99 ± 18 W, P=0.031; Girls: 1.02 ± 0.25 L·min vs. Boys: 1.22 ± 0.28 L·min, P=0.014). However, when expressed against relative work-rate or V˙O2, there were no sex differences in [HHb] response dynamics (all P>0.20). Significant correlations were observed between absolute and fat-free mass normalised peak V˙O2 and the HHb c/d and plateau parameters when expressed against absolute work-rate or V˙O2. Furthermore, when entered into a multiple regression model, the [HHb] plateau against absolute V˙O2 contributed 12% of the variance in peak V˙O2 after adjusting for fat-free mass, gas exchange threshold, and body fatness (model R =0.81, P<0.001).CONCLUSION:The sex-difference in peak V˙O2 in 9-10 year old children is, in part, related to sex-specific changes in muscle O2 extraction dynamics during incremental exercise.
NIRS; O2 delivery; O2 utilization; peak V O2; pre-pubertal; sex
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