The validity and reliability of the Cosmed K2 was tested in comparison with a Quinton on-line oxygen analysing system. A female subject was monitored on a treadmill using a progressive protocol and was measured on three occasions with each system. It was found at low workloads that the Cosmed K2 and the Quinton gave the same measure of oxygen uptake; at higher workloads the Cosmed K2 gave lower values, and at peak oxygen uptake the Cosmed K2 measured 22.2% less than the Quinton. The difference in the measurement of VE at peak oxygen uptake was 13%. The Cosmed K2's measurement of VO2 showed a greater variability between trials (variation coefficient 3.0-11.4%) than the Quinton (variation coefficient 1.1-3.9%).
We tested the hypothesis that priming exercise would speed kinetics during treadmill running. Eight subjects completed a square-wave protocol, involving two bouts of treadmill running at 70% of the difference between the running speeds at lactate threshold (LT) and max, separated by 6-min of walking at 4 km h −1 , on two occasions. Oxygen uptake was measured breath-by-breath and subsequently modelled using non-linear regression techniques. Heart rate and blood lactate concentration were significantly elevated prior to the second exercise bout compared to the first. However, kinetics was not significantly different between the first and second exercise bouts (mean ± S.D., phase II time constant,
Sixteen female games players completed 15 min of intermittent exercise on a treadmill. The speed and incline of the treadmill were varied to elicit a similar heart rate response to that found during women's hockey match-play. The mean heart rate response was 169 +/- 8 beats min-1 and the mean work:rest ratio was 1:1.7. Oxygen uptake was estimated by applying the oxygen cost determined from an individual's heart rate-oxygen uptake regression equation to the average heart rate each 5 s during the intermittent exercise. A second estimation of oxygen uptake was made from a time-motion analysis by assigning a specific oxygen cost to each discrete movement during the intermittent exercise protocol. The true oxygen cost was calculated from the analysis of the expired gas. The heart rate analysis overestimated the true cost by a mean of 4.3 +/- 5.3% (0.09 +/- 0.11 l min-1), and the time-motion analysis underestimated the true value by a mean of 15.7 +/- 6.3% (0.34 +/- 0.15 l min-1). There was a significant difference (P < 0.01) between the true value and both the estimates. It was concluded that heart rate analysis gives a much better indication of oxygen uptake during intermittent activity than time-motion analysis.
Thompson and Cooper1 observed that improvements in the swimming speed at 2-mM and 6-mM lactate concentration coincided with improvements in competitive breaststroke performances, whereas Pyne et al2 concluded that changes in swimming speed at lactate threshold were not directly associated with competition performances in a mixed-stroke group of 12 elite swimmers. This case study presents data from eleven (7 × 200 m) step tests over a 3-year period for a world-class 200-m male breaststroke swimmer. Personal-best race times were reduced by 9.5 seconds over this period. For this individual, step-test data provided valuable information with regard to the swimmer’s readiness for performance, health and training status, and nutritional habits.
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