We tested the hypothesis that priming exercise (PE) would increase the speed of the adjustment of the primary phase (taup, tp) of pulmonary oxygen uptake (VO2) and/or reduce the amplitude of the slow component of VO2 during high-intensity cycling in type 2 diabetes (T2D) given that muscle oxygen supply appears to be limited in T2D. Ten middle-aged participants with uncomplicated T2D (49.6 ± 7.2 years, 30.8 ± 5.0 kg.m2; 8 men / 2 women) and 10 non-diabetic (ND) controls (44.6 ± 9.2 years, 30.8 ± 4.2 kg.m2; 8 men / 2 women) were recruited. Participants completed four bouts of constant-load cycling corresponding to 50% between their ventilatory threshold and VO2 peak power outputs, (i.e. 50%delta) previously established during a ramp incremental test. Two of these bouts were completed without priming exercise and two bouts were undertaken with prior heavy-intensity (50%delta) priming exercise. VO2 kinetics was calculated from continuously measured breath-by-breath data, while the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) was continuously measured by near–infrared spectroscopy (NIRS) at the vastus lateralis muscle. At baseline the time constant of the primary phase, tp, was approximately 17% slower (P>0.05) in T2D, and PE tended to reduce tp (P = 0.06) in both groups by a similar magnitude (T2D, 37.9±17.7 vs. 33.7±10.6 s; ND, 31.0±5.8 vs. 28.0±6.3 s). The amplitude of the slow component (As) was overall significantly lower (P<0.05) in T2D; and PE tended to overall reduce it (P=0.09). These reductions were of approximately 50% in T2D and only 5% in ND controls (T2D, 0.29±0.13 vs 0.18±0.10 L.min-1; ND, 0.39±0.18 vs 0.37±0.21 L.min-1), however, there was no significant interaction between diabetes status and priming bout in As (P = 0.22). The rate of adjustment or amplitude of deoxygenated heamoglobin (HHb) did not show any differences between groups. These preliminary data suggest that in middle-aged adults with T2D, priming exercise prior to heavy intensity exercise can potentially speed the primary phase VO2 kinetics and reduce the amplitude of the slow component possibly due to an improvement in oxygen delivery. Nevertheless inter-individual variability in responses precluded the attainment of statistical significance.
|Publication status||Published - Jul 2016|
|Event||21st Annual Congress of the European College of Sport Science: Crossing Borders Through Sport Science - Centre for Sport Science and University Sports, Vienna, Austria|
Duration: 6 Jul 2016 → 9 Jul 2016
|Conference||21st Annual Congress of the European College of Sport Science|
|Period||6/07/16 → 9/07/16|