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  • Title: Acute Apnea Does Not Improve 3-km Cycling Time Trial Performance.
    Author: Bouten J, Colosio AL, Bourgois G, Lootens L, VAN Eenoo P, Bourgois JG, Boone J.
    Journal: Med Sci Sports Exerc; 2020 May; 52(5):1116-1125. PubMed ID: 31809413.
    Abstract:
    PURPOSE: Intense exercise evokes a spleen contraction releasing red blood cells into blood circulation. The same mechanism is found after acute apnea, increasing hemoglobin concentration ([Hb]) by 2% to 5%. The aim of this study was twofold: [1] to identify the optimal apnea modalities to acutely increase [Hb] and [2] use these modalities to examine whether prerace apnea can improve a 3-km time trial (TT). METHODS: In part 1, 11 male subjects performed 12 different apnea protocols based on three modalities: mode, frequency, and intensity. Venous blood samples for [Hb] were collected before, immediately, and 5 min after each protocol. In part 2, 12 recreationally active subjects performed 3-km cycling TT in three different conditions: apnea, control, and placebo, after a 10-min warm-up. Power output, HR, and oxygen uptake (V˙O2) were continuously measured. Venous [Hb] was sampled at baseline, after warm-up, and before TT. Additionally, these subjects performed constant cycling at Δ25 (25% between gas exchange threshold and V˙O2 max) in two conditions (control and apnea) to determine V˙O2 kinetics. RESULTS: Although including one single apnea in the warming up evoked a positive change in [Hb] pattern (P = 0.049) and one single apnea seemed to improve V˙O2 kinetics in constant submaximal cycling (τ: P = 0.060, mean response time: P = 0.064), performance during the 3-km TT did not differ between conditions (P = 0.840; apnea, 264.8 ± 14.1 s; control, 263.9 ± 12.9 s, placebo, 264.0 ± 15.8 s). Average normalized power output (P = 0.584) and V˙O2, HR, and lactate did not differ either (P > 0.05). CONCLUSIONS: These results suggest that potential effects of apnea, that is, speeding of V˙O2 kinetics through a transient increase in [Hb], are overruled by a warming-up protocol.
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