No description available.

No description available.

An attempt was made to evaluate the applicability of a theorized model concerning plasma lactic acid kinetics to running performance assessment. This model incorporated two distinct lactate thresholds identified as the aerobic threshold (AerT) and the anaerobic threshold (AT). Two groups of males with different levels of fitness were tested. Group 1 (n = 5) consisted of recreational athletes (͞X VO₂ max = 49.3 ml/kg•min⁻¹) who ran less than 20 miles per week, while Group 2 (n = 6) were highly trained runners (͞X VO₂ max = 65.5 ml/kg•min⁻¹) who all ran at least 40 miles per week. All subjects participated in two incremental work load (IWL) and four constant work load (CWL) tests that consisted of horizontal treadmill running at different speeds. The IWL tests elicited linear increases in VO₂ and were highly correlated for both Group 1 (r = .986) and Group 2 (r = .999). However, three unbiased observers found the identification of both AerT and AT, using independent lactate and respiratory gas exchange "breakpoints," very subjective in nature. The test-retest reliablity was generally poor and varied considerably among both the observers and the individual predictor variables. The validity of the respiratory gas exchange predictors was then evaluated against the criterion lactate thresholds using the estimates of a fourth, more experienced observer. The resultant correlation coefficients were generally not high, while t-test evaluation demonstrated significant (p < .05) differences in fifty percent of the cases. This same observer then pooled all of the ventilatory predictors in an effort to better estimate both AerT and AT indirectly. These indirect ventilatory estimates consistently underpredicted the criterion lactate thresholds. This finding suggests that increases in running speeds may confound the normal associate between plasma lactate and ventilation at increasing work levels. Arbitrary lactate concentrations of 2mmol/2 and 4 mmol/L were further evaluated as threshold predictors. This methodology consistently overpredicted the criterion lactate thresholds in terms of VO₂. When any of these AerT and AT threshold estimates were compared to the lactate responses during the appropriate CWL test, no meaningful relationship were found. These observations question the physiological significance of both AerT and AT evaluation during treadmill running, as well as pointing out the difficulty in reliably detecting both plasma lactate thresholds regardless of the methodology.

No description available.

No description available.

There were two primary goals in this investigation. The first goal was to determine if inter-individual variability in time to exhaustion at the velocity associated with V02max (Tlim at Vmax) was explained by anaerobic capacity (AC), Vmax, anaerobic threshold (AT), and/or a combination variable in the form [AC • (Vmax - vAT)^-1]. The second goal was to determine if AC could be predicted from Tlim at Vmax, AT, and/or a combination variable in the form [Tlim • (Vmax - vAT)].

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This study compared the plantar force distribution between forward ice hockey skating and treadmill skating. Four varsity hockey players from McGill University (age = 22.1 +/- 1.2 years, height = 1.8 +/- 0.1 m, mass = 82.2 +/- 8.6 kg) skated on ice surface and on a specialized treadmill at three velocities (22, 24 and 26 +/- 0.5 km/hr). Results showed higher plantar forces were seen during treadmill skating prior to push off and this discrepancy was due to consistently larger forces in the fore region of the foot. This phenomenon was speculated to be the result of differences in skate stability during ice and treadmill skating. With respect to the loading dynamics, the heel region was the same during ice and treadmill skating.

The purpose of this study was to investigate the effect of skate blade hollow on oxygen consumption during forward skating on a treadmill. Varsity level female hockey players ( n = 10, age = 21.7 yr) performed skating tests at three blade hollows (0.25 in, 0.50 in, and 0.75 in). The subjects skated for four minutes at three submaximal velocities (12, 14, and 16 km/h), separated by five minutes of passive recovery. In addition, a VO^max test was performed on the day that the subjects skated at the 0.50 in hollow. The VOimax test commenced at 14 km/h and increased by 1 km/h each minute until volitional exhaustion was achieved. Four variables were measured for each skating bout, volume of gas expired (VE), volume of oxygen consumed (VO2), heart rate (HR) and rating of perceived exertion (RPE). No significant differences (pO.05) were found in any of the four test variables (VE, VO2, HR, RPE) across the three skate hollows. These results show that when skating on a treadmill at submaximal velocities, skate blade hollow has no significant effect on VE, VO2, HR or RPE.