The effect of exercise intensity and cardiorespiratory fitness on the kinetic response of middle cerebral artery blood velocity during exercise in healthy adults

Figures

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  Figure 1.. A representative trace for one participant for moderate (A) and heavy (B) intensity cycling. Data shown as an average of left and right MCAv responses across three repeat transitions, with the residual plot included below each figure. Time 0 s indicates onset of exercise. Data show a clear delay from exercise onset before MCAv increased exponentially. In A, MCAv attained a steady state, and the monoexponential was fit to the end of exercise (360 s). In B, a clear decrease in MCAv seen from t = 141 s, representing the end of the model fit. MCAv, middle cerebral artery blood velocity; τ, time constant; TD, time delay.

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  Figure 2.. Group-averaged absolute (A) and relative (B) middle cerebral artery blood velocity (MCAv) responses to moderate (gray line) and heavy (black line) intensity cycling in healthy adults (n = 17, 9 females). Dashed line indicates exercise onset. Δ%, relative change from baseline.

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  Figure 3.. Correlations between V̇o2max and MCAv amplitude (A: absolute terms; B: relative change from baseline) and MCAv time constant, τ (C). Data shown for moderate-intensity exercise (circles, dashed line) and heavy-intensity exercise (black triangles, solid line) (n = 17, 9 females). MCAv, middle cerebral artery blood velocity; V̇o2max, maximal oxygen uptake.

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  Figure 4.. Group-averaged oxygen uptake (V̇o2, A), minute ventilation (V̇e, B), and heart rate responses (C) to moderate (gray line) and heavy (black line) intensity cycling in healthy adults (n = 17, 9 females).