| Autor: |
Grossman KJ; School of Kinesiology, The University of Western Ontario, London, ON, Canada., Lim DJ; School of Kinesiology, The University of Western Ontario, London, ON, Canada., Murias JM; Faculty of Kinesiology, University of Calgary, Calgary, ON, Canada., Belfry GR; School of Kinesiology, The University of Western Ontario, London, ON, Canada. |
| Jazyk: |
angličtina |
| Zdroj: |
Frontiers in physiology [Front Physiol] 2021 Nov 24; Vol. 12, pp. 723951. Date of Electronic Publication: 2021 Nov 24 (Print Publication: 2021). |
| DOI: |
10.3389/fphys.2021.723951 |
| Abstrakt: |
During competitive freestyle swimming, the change of direction requires a turn followed by ∼15 m of underwater kicking at various intensities that require a ∼5 s breath-hold (BH). Upon surfacing, breathing must be regulated, as head rotation is necessary to facilitate the breath while completing the length of the pool (∼25 s). This study compared the respiratory and muscle deoxygenation responses of regulated breathing vs. free breathing, during these 25-5 s cycles. It was hypothesized that with the addition of a BH and sprint during heavy-intensity (HVY) exercise, oxygen uptake (VO 2 ) and oxygen saturation (S at O 2 ) would decrease, and muscle deoxygenation ([HHb]) and total hemoglobin ([Hb tot ]) would increase. Ten healthy male participants (24 ± 3 years) performed 4-6 min trials of HVY cycling in the following conditions: (1) continuous free breathing (CONLD); (2) continuous with 5 s BH every 25 s (CONLD-BH); (3) Fartlek (FLK), a 5 s sprint followed by 25 s of HVY; and (4) a combined Fartlek and BH (FLK-BH). Continuous collection of VO 2 and S at O 2 , [Hb tot ], and [HHb] via breath-by-breath gas analysis and near-infrared spectroscopy (normalized to baseline) was performed. Breathing frequency and tidal volumes were matched between CONLD and CONLD-BH and between FLK and FLK-BH. As a result, VO 2 was unchanged between CONLD (2.12 ± 0.35 L/min) and CONLD-BH (2.15 ± 0.42 L/min; p = 0.116) and between FLK (2.24 ± 0.40 L/min) and FLK-BH (2.20 ± 0.45 L/min; p = 0.861). S at O 2 was higher in CONLD (63 ± 1.9%) than CONLD-BH (59 ± 3.3%; p < 0.001), but was unchanged between FLK (61 ± 2.2%) and FLK-BH (62 ± 3.1%; p = 0.462). Δ[Hb tot ] is higher in CONLD (3.3 ± 1.6 μM) than CONLD-BH (-2.5 ± 1.2 μM; Δ177%; p < 0.001), but was unchanged between FLK (2.0 ± 1.6 μM) and FLK-BH (0.82 ± 1.4 μM; p = 0.979). Δ[HHb] was higher in CONLD (7.3 ± 1.8μM) than CONLD-BH (7.0 ± 2.0μM; Δ4%; p = 0.011) and lower in FLK (6.7 ± 1.8μM) compared to FLK-BH (8.7 ± 2.4 μM; p < 0.001). It is suggested that the unchanged VO 2 between CONLD and CONLD-BH was supported by increased deoxygenation as reflected by decreased Δ[Hb tot ] and blunted Δ[HHb], via apneic-driven redistribution of blood flow away from working muscles, which was reflected by the decreased S at O 2 . However, the preserved VO 2 during FLK-BH vs. FLK has been underpinned by an increase in [HHb].
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2021 Grossman, Lim, Murias and Belfry.) |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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