Priming exercise accelerates oxygen uptake kinetics during high-intensity cycle exercise in middle-aged individuals with type 2 diabetes

Figures

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  FIGURE 1. Schematic representation of the protocol. Unprimed and primed cycling step transitions performed at high-intensity cycling exercise (Δ50%; the sum of the power output at VT and 50% of the difference between the power output at VT and V·O2 peak). All step transitions, each lasting 6 min, were preceded by 3 min of cycling at 10 W (i.e. ‘baseline’ cycling). Unprimed and primed transitions were separated by 12 min of passive rest. The 2 step transitions (unprimed and primed) were repeated following 45–60 min of passive rest within the same laboratory visit.

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  FIGURE 2. Oxygen uptake ( V·O2 ) responses for a representative healthy control ((A): absolute values; (B): normalised to the % primary phase V·O2 amplitude) and an individual with type 2 diabetes ((C): absolute values; (D): normalised to the % primary phase V·O2 amplitude) during high-intensity cycling transitions without priming exercise (open circles) and with priming exercise (solid circles). The vertical line illustrates the abrupt transition to the higher work rate. The continuous lines of best fit illustrate the primary phase of the oxygen uptake ( V·O2 ) response. Note the relatively slower response of the primary phase of the V·O2 response in the unprimed compared with the primed bout in T2D.

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  FIGURE 3. Individual and mean ± SD (bar graph) changes in time constant of the primary phase of oxygen uptake ( V·O2 τ p) (A) and amplitude of the V·O2 slow component ( V·O2 As) (B) in participants with type 2 diabetes (n = 11) and healthy controls (n = 11) during high-intensity cycling transitions without priming exercise (unprimed) and with priming exercise (primed). *p < 0.05 vs. unprimed within the same diabetes status group (i.e., within controls or within Type 2 diabetes). † p < 0.05 vs. healthy controls within the same condition (i.e., within unprimed or primed).

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  FIGURE 4. Changes in deoxygenated hemoglobin and myoglobin concentration [Δ (HHb + Mb)] for a representative healthy control (A) and an individual with type 2 diabetes (B) during high-intensity cycling transitions without priming exercise (open circles) and with priming exercise (solid circles). The vertical line illustrates the abrupt transition to the higher work rate. The continuous black lines of best fit illustrate the primary phase of the Δ (HHb + Mb) response. Note the time constant of the primary phase of the Δ [HHb + Mb] response is not affected by prior priming exercise in any of the 2 groups.