Key result
Endurance athletes show delayed onset of cerebral autoregulation with ~1.6-second longer response times vs. controls.
Why the study?
Does elevated cardiorespiratory fitness in male endurance athletes alter dynamic cerebral autoregulatory capacity and orthostatic tolerance during spontaneous and forced oscillations in mean arterial pressure compared to recreationally active controls?
Cross-Sectional (n=27)
The sequence of the squat-stand maneuvers was randomized between participants.
No
Does elevated cardiorespiratory fitness in male endurance athletes alter dynamic cerebral autoregulatory capacity and orthostatic tolerance during spontaneous and forced oscillations in mean arterial pressure compared to recreationally active controls?
Elevated cardiorespiratory fitness in young male endurance athletes is associated with an intact cerebrovascular response to spontaneous blood pressure fluctuations but a delayed and attenuated capability to buffer rapid, large forced oscillations in mean arterial pressure, without worsening orthostatic tolerance.
Answers are grounded in this paper and cite their sources.
May indicate altered dynamic cerebral autoregulation in endurance athletes during forced oscillations; leaves open clinical relevance and should not yet change practice.
The effect that cardiorespiratory fitness has on the dynamic cerebral autoregulatory capacity during changes in mean arterial pressure ( MAP ) remains equivocal. Using a multiple‐metrics approach, challenging MAP across the spectrum of physiological extremes (i.e., spontaneous through forced MAP oscillations), we characterized dynamic cerebral autoregulatory capacity in 19 male endurance athletes and eight controls via three methods: (1) onset of regulation (i.e., time delay before an increase in middle cerebral artery ( MCA ) conductance [ MCA blood velocity ( MCA v)/ MAP ] and rate of regulation, after transient hypotension induced by sit‐to‐stand, and transfer function analysis ( TFA ) of MAP and MCA v responses during (2) spontaneous and (3) forced oscillations (5‐min of squat‐stand maneuvers performed at 0.05 and 0.10 Hz). Reductions in MAP and mean MCA v ( MCAV mean ) during initial orthostatic stress (0‐30 sec after sit‐to‐stand) and the prevalence of orthostatic hypotension were also determined. Onset of regulation was delayed after sit‐to‐stand in athletes (3.1 ± 1.7 vs. 1.5 ± 1.0 sec; P = 0.03), but rate of regulation was not different between groups (0.24 ± 0.05 vs. 0.21 ± 0.09 sec −1 ; P = 0.82). While both groups had comparable TFA metrics during spontaneous oscillations, athletes had higher TFA gain during 0.10 Hz squat‐stand versus recreational controls ( P = 0.01). Reductions in MAP ( P = 0.15) and MCAV mean ( P = 0.11) during orthostatic stress and the prevalence of initial orthostatic hypotension ( P = 0.65) were comparable between groups. These results indicate an intact ability of the cerebral vasculature to react to spontaneous oscillations but an attenuated capability to counter rapid and large changes in MAP in individuals with elevated cardiorespiratory fitness.
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Labrecque et al. (2017) conducted a cross-sectional in Healthy adult males with varying cardiorespiratory fitness (endurance athletes vs. controls) (n=27). Elevated cardiorespiratory fitness (endurance-trained athletes) vs. Inactive/moderately active recreational controls was evaluated on Time delay before onset of cerebral autoregulation (sec) after transient hypotension induced by sit-to-stand (p=0.03). Endurance athletes had a delayed onset of cerebral autoregulation after sit-to-stand and higher transfer function gain during 0.10 Hz squat-stand vs. controls.
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