2.1. Subjects

Thirty males and 13 females, all healthy and physically active agreed to participate in this investigation (Table 1). The inclusion criteria for participation in this investigation were: aged 18–35 years old; non-smoking; normal resting electrocardiogram, no chronic diseases or recent surgery; body mass index between 18 and 30 kg·m⁻²; no medical contraindications to exercise and no history of disease requiring medical treatments lasting longer than 15 days during the preceding six months. Subjects were requested to avoid strenuous exercise 48 h before the laboratory test and not to drink carbonated, caffeinated and alcohol-containing beverages during the 24 h preceding all tests. During the study period, subjects were also requested to abstain from the consumption of drugs, medications, and any dietary supplements. Sex and gender of the participants were defined based on self-report during participant recruitment. All participants reported cis-gender, and thereafter the terms males and females were applied in the study analysis and reporting [39]. All females were eumenorrheic, without taking oral contraceptives and were evaluated randomly in different phases of the menstrual cycle [40]. This approach is based on the similar sprint and high-intensity exercise responses observed in different phases of the menstrual cycle [[41], [42], [43]].

Physical characteristics and ergoespirometric variables (mean ± SD).

HRmax: maximal heart rate; VO_2max: maximal oxygen uptake; Wmax: maximal intensity during the incremental exercise test to exhaustion; LLM: lean mass of the lower extremities; Accumulated O₂: total amount of O₂ consumed during the test; and the average values during the 120% CP test for: RER, respiratory exchange ratio; V_E, pulmonary ventilation; RR, respiratory rate; P_ETO₂, end tidal O₂ pressure; P_ETCO₂, end tidal CO₂ pressure; TOI, tissue oxygenation index; MCAv, middle cerebral artery velocity. Note: the supramaximal test data correspond to the session with the best performance time. P values based on two-tailed unpaired t-tests.

The study was approved by the Ethical Committee of the University of Las Palmas de Gran Canaria (Ref.: CEIH-2017-13) and performed in accordance with the standards set by the latest revision of the Declaration of Helsinki, except for registration in a database. All subjects signed a written informed consent before the start of the study.