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

Abstract

Background: The primary phase time constant of pulmonary oxygen uptake kinetics (V·O2τp) during submaximal efforts is longer in middle-aged people with type 2 diabetes (T2D), partly due to limitations in oxygen supply to active muscles. This study examined if a high-intensity “priming” exercise (PE) would speed V·O2τp during a subsequent high-intensity cycling exercise in T2D due to enhanced oxygen delivery.Methods: Eleven (4 women) middle-aged individuals with type 2 diabetes and 11 (4 women) non-diabetic controls completed four separate cycling bouts each starting at an ‘unloaded’ baseline of 10 W and transitioning to a high-intensity constant-load. Two of the four cycling bouts were preceded by priming exercise. The dynamics of pulmonary V·O2 and muscle deoxygenation (i.e. deoxygenated haemoglobin and myoglobin concentration [HHb + Mb]), were calculated from breath-by-breath and near-infrared spectroscopy data at the vastus lateralis, respectively.Results: At baseline V·O2τp, was slower (p < 0.001) in the type 2 diabetes group (48 ± 6 s) compared to the control group (34 ± 2 s) but priming exercise significantly reduced V·O2τp (p < 0.001) in type 2 diabetes (32 ± 6 s) so that post priming exercise it was not different compared with controls (34 ± 3 s). Priming exercise reduced the amplitude of the V·O2 slow component (As) in both groups (type 2 diabetes: 0.26 ± 0.11 to 0.16 ± 0.07 L/min; control: 0.33 ± 0.13 to 0.25 ± 0.14 L/min, p < 0.001), while [HHb + Mb] kinetics remained unchanged.Conclusion: These results suggest that in middle-aged men and women with T2D, PE speeds V·O2τp likely by a better matching of O2 delivery to utilisation and reduces the V·O2 As during a subsequent high-intensity exercise.

How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance

“…For instance, prior heavy exercise performed in the supine or prone positions reduces during subsequent heavy exercise [ 2 , 7 , 16 , 54 , 55 ]. Moreover, prior heavy exercise reduced during subsequent moderate exercise in healthy elderly individuals [ 56 ], patients with type 2 diabetes mellitus [ 57 , 58 ] and heart failure [ 59 ], and healthy individuals with initially slow kinetics [ 60 ], in contrast to healthy young active individuals. In each of these cases, O 2 kinetics is markedly slowed in the initial bout of heavy warm-up exercise compared with O 2 kinetics typically observed during upright cycle exercise in young healthy individuals.…”

“…O 2 delivery is generally considered to constrain O 2 kinetics during supine exercise [ 54 , 94 , 95 ] and various clinical conditions (e.g. type 2 diabetes [ 57 , 96 ]), and in some studies, prior exercise has been shown to reduce during supine, but not upright exercise [ 2 , 7 , 54 ] and in diabetic patients but not healthy controls [ 58 ] (although see [ 57 ] for alternative findings from the same group). In the canine hindlimb model, there was a concomitant speeding of muscle blood flow on-kinetics and a reduction in at the onset of a second bout of muscle contractions [ 97 ].…”

Muscle deoxygenation during ramp incremental cycle exercise in older adults with type 2 diabetes

“…This decrement is clinically significant given that V̇O 2peak is an established clinical predictor of cardiovascular and all-cause mortality (Wei et al 2000 ). While the mechanisms for the reduced V̇O 2peak responses in T2D are inconclusive, important mediators include systemic cardiovascular limitations (e.g., impaired left ventricular filling (Wilson et al 2017a , 2017b )), reductions in peripheral vasodilation and/or microvascular dysfunction in the lower limbs (Gildea et al 2021c ; Rocha et al 2022 ; Gildea et al 2019 ; Rocha et al 2019 ; Poitras et al 2015 ; MacAnaney et al 2011 ), or decreased mitochondrial content and function (Ritov et al 2005 ; Boushel et al 2007 ).…”