The elevated CO2 levels, elevated temperature, and lower blood pH that may occur during exercise should enhance O2 delivery to the exercising muscles. It was hypothesized that performance of prior exercise (PE) would result in a faster VO2 response, as well as a reduced slow component contribution, in subsequent exercise bouts. Five women (21 ± 1 yr) and 10 men (23 ± 2 yr) performed nine 6-min bouts of heavy intensity cycle ergometer exercise (i.e., above the ventilatory threshold, individually determined by an incremental test). Three bouts were performed without prior heavy exercise (noPE), three were performed 6 min after a 6-min bout of heavy intensity arm cranking (PEA), and three were performed 6 min after a 6-min bout of heavy intensity cycle ergometer exercise (PEL). Breath-by-breath VO2 data from each of the three sets of three tests were combined and fitted to a two-component model, which ignores the cardiodynamic phase. The primary and slow component amplitudes were truncated to reflect actual increases in VO2 in each phase. The effects of PE on the time constant of the primary component were inconsistent. As hypothesized, the amplitude of the slow component was reduced by PE (noPE vs PEA vs. PEL: 25% > 16% < 14%; p < .05). It is concluded that heavy intensity PE affects characteristics of the VO2 profile in a subsequent bout of heavy intensity leg exercise.

Purpose: The aim of this study was to determine the influence of 30min. of moderate and heavy intensity aerobic exercise to heart rate during interval incremental exercise. Methods: Eight healthy males (mean SD 23 1yr; 76 4,8 kg; 178 6,6 cm) were tested 3 times. They performed incremental veloergometer exercise test until subjective exhaustion. Pedalling rate was maintained constant at 70 rpm. Test began with 4 min. of cycling at 25 W. Then the workload was increased by 25 W and maintained for 3 min. until participant ,s heart rate (HR) reached 90 % of HRmax (220 - age, year). Between workloads the participants rested for 4 min. Two times exercise was preceded by 30 min. of moderate (equal to lactate threshold), heavy intensity (50 W heavier than lactate threshold) or no warm-up. Capillary blood samples were drawn from finger to measure lactate concentration at rest and 5, 10, 20, 30, min. during work. HR was registered before exercise and every 5 min. during work. Also HR was recorded every 5 s. during interval incremental veloergometer test. The heart rate data were modelled using single exponential models, which included amplitudes, time constants and asimptotics values. Results: Heart rate was more elevated during heavy warm-up compared to the moderate (3 min. – 140 13,7; 13 min. – 158 16,1; 23 min. – 164 13,6; 26 min. - 167 13,7 and 3 min. – 128 8,7; 13 min. – 134 11,2; 23 min. – 140 11,2; 26 min. – 142 10,9 beats/min. respectively). Heavy warm-up resulted... [to full text]