Abstract
IntroductionOral contraceptive (OC) use influences peak exercise responses to training, however, the influence of OC on central and peripheral adaptations to exercise training are unknown. This study investigated the influence of OC use on changes in time-to-fatigue, pulmonary oxygen uptake, cardiac output, and heart rate on-kinetics, as well as tissue saturation index to 4 weeks of sprint interval training in recreationally active women.MethodsWomen taking an oral contraceptive (OC; n = 25) or experiencing natural menstrual cycles (MC; n = 22) completed an incremental exercise test to volitional exhaustion followed by a square-wave step-transition protocol to moderate (90% of power output at ventilatory threshold) and high intensity (Δ50% of power output at ventilatory threshold) exercise on two separate occasions. Time-to-fatigue, pulmonary oxygen uptake on-kinetics, cardiac output, and heart rate on-kinetics, and tissue saturation index responses were assessed prior to, and following 12 sessions of sprint interval training (10 min × 1 min efforts at 100–120% PPO in a 1:2 work:rest ratio) completed over 4 weeks.ResultsTime-to-fatigue increased in both groups following training (p < 0.001), with no difference between groups. All cardiovascular on-kinetic parameters improved to the same extent following training in both groups. Greater improvements in pulmonary oxygen up-take kinetics were seen at both intensities in the MC group (p < 0.05 from pre-training) but were blunted in the OC group (p > 0.05 from pre-training). In contrast, changes in tissue saturation index were greater in the OC group at both intensities (p < 0.05); with the MC group showing no changes at either intensity.DiscussionOral contraceptive use may reduce central adaptations to sprint interval training in women without influencing improvements in exercise performance - potentially due to greater peripheral adaptation. This may be due to the influence of exogenous oestradiol and progestogen on cardiovascular function and skeletal muscle blood flow. Further investigation into female-specific influences on training adaptation and exercise performance is warranted.
Highlights
Oral contraceptive (OC) use influences peak exercise responses to training, the influence of oral contraceptive (OC) on central and peripheral adaptations to exercise training are unknown
Exogenous ovarian hormones found in the oral contraceptive pill may be, at least in part, responsible for the dampened physiological adaptations to training in OC users
Both OC users and naturally menstruating women improved TTF, we observed a dampened response of central physiological adaptation, demonstrated by pulmonary oxygen uptake kinetics in the OC group
Summary
Oral contraceptive (OC) use influences peak exercise responses to training, the influence of OC on central and peripheral adaptations to exercise training are unknown. Exogenous hormones introduced through oral contraceptive (OC) use can reduce maximal exercise capacity (Notelovitz, 1987; Casazza et al, 2002; Lebrun et al, 2003), increase fatmass (Berenson and Rahman, 2009) and change the metabolic (Isacco et al, 2012), thermoregulatory (Stachenfeld et al, 2000), cardiovascular (Coney et al, 2001), and ventilatory (Charkoudian and Joyner, 2004) responses to exercise. Altered muscle blood flow due to endogenous and exogenous ovarian hormones may influence the ability of the muscle to meet oxidative demands during exercise. This has not been investigated, nor has OC use been considered as a potential mediator of skeletal muscle blood flow adaptations to exercise training in women
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