Oxygen uptake kinetics in trained adolescent females

Little evidence exists with regard to the effect that exercise training has upon oxygen uptake kinetics in adolescent females.

Purpose

The aim of the study was to compare V˙O2V˙O2 and muscle deoxygenation kinetics in a group of trained (Tr) and untrained (Utr) female adolescents.

Method

Twelve trained (6.4 ± 0.9 years training, 10.3 ± 1.4 months per year training, 5.2 ± 2.0 h per week) adolescent female soccer players (age 14.6 ± 0.7 years) were compared to a group (n = 8) of recreationally active adolescent girls (age 15.1 ± 0.6 years) of similar maturity status. Subjects underwent two, 6-min exercise transitions at a workload equivalent to 80 % of lactate threshold from a 3-min baseline of 10 W. All subjects had a passive rest period of 1 h between each square-wave transition. Breath-by-breath oxygen uptake and muscle deoxygenation were measured throughout and were modelled via a mono-exponential decay with a delay relative to the start of exercise.

Result

Peak V˙O2V˙O2 was significantly (p < 0.05) greater in the Tr compared to the Utr (Tr: 43.2 ± 3.2 mL kg−1 min−1 vs. Utr: 34.6 ± 4.0 mL kg−1 min−1). The V˙O2V˙O2 time constant was significantly (p < 0.05) faster in the Tr compared to the Utr (Tr: 26.3 ± 6.9 s vs. Utr: 35.1 ± 11.5 s). There was no inter-group difference in the time constant for muscle deoxygenation kinetics (Tr: 8.5 ± 3.0 s vs. Utr: 12.4 ± 8.3 s); a large effect size, however, was demonstrated (−0.804).

Conclusion

Exercise training and/or genetic self-selection results in faster kinetics in trained adolescent females. The faster V˙O2V˙O2 kinetics seen in the trained group may result from enhanced muscle oxygen utilisation.