This programme of work aimed to explore critical power and anaerobic work capacity in upper body exercise, using models commonly applied to lower body exercise. Sixteen untrained male subjects performed upper body exercise on a modified cycle ergometer. They carried out three habituation bouts and two maximal incremental bouts, which were followed by two sets of five constant power bouts in a randomised order. The results from the second set of constant power bouts were used to compare estimates of critical power and anaerobic work capacity from; the linear work vs. time model, the linear time vs. work model, the linear power vs. Iltime model, the hyperbolic power vs. time model, the exponential model and the three parameter non-linear model. The 3-parameter model provided critical power estimates that were very likely to be less than the other models studied, and values of anaerobic work capacity that were very likely to be greater than all of the other models. The exponential model provided estimates of critical power that were almost certainly greater than all of the other models. This would suggest that the selection of model can have marked and systematic effects on the magnitude of the derived parameters. Results from the two sets of constant power bouts were then used to examine their repeatability, and the repeatability of critical power and anaerobic work capacity derived from the linear work vs. time model (when work or time was identified as the dependent variable), the linear power vs. IItime model and the hyperbolic model. The repeatability of the parameters of the exponential model was also determined. There was evidence of heteroscedastic error in the measurement of time to exhaustion in the constant power bouts with a typical error of 18%. A typical error of critical power of between 5 to 6W was evident in the models studied, whilst a 9% typical percentage error was evident for critical power from the exponential model. The typical error in measures of anaerobic work capacity was 17-24%. The relatively poor repeatability of estimates of critical power and anaerobic work capacity may limit their practical application in identifying a particular exercise intensity and in assessing the effect of training and dietary interventions. The effect on parameter estimates of progressively reducing the number of bouts from five to four, three or two bouts was assessed, using combinations of bouts selected to clarify whether any effect was due to the number or the range of bouts. The effect of using as few as two bouts was assessed for the linear work vs. time model and the linear power vs. 11 • time model. The effect on the hyperbolic power vs. time model of progressively reducing the number of bouts to three was also assessed. Combinations of bouts that included higher power output bouts, tended to elevate critical power estimates and reduce estimates of anaerobic work capacity. Selecting a small number of two or three low intensity bouts tended to reduce critical power estimates and elevate anaerobic work capacity in the models studied. There was a tendency towards a reciprocal effect, whereby if critical power was elevated, anaerobic work capacity was reduced and vice versa. Within models, the effect of reducing the range of constant power bouts appeared to be more marked than the effect of reducing the number of bouts. Critical power is thought to identify a threshold of tolerable duration and physiological response in lower body exercise. To determine whether critical power from the hyperbolic model identified a similar threshold of duration and physiological response in upper body exercise, subjects performed two exercise bouts at critical power determined from the hyperbolic model, the mean durations of which were 22.4 ± 10.6 and 23.1 ± 11.3 minutes, with a typical error of 84s. A variety of patterns of physiological response were evident and critical power from the hyperbolic model in upper body exercise did not characterise the intensity associated with the highest steady state values of V02 or blood lactate in all subjects. The results indicate that values of critical power and anaerobic work capacity in upper body exercise are affected by the selection of model and aspects of experimental protocol such as the number and range of bouts, which affects their repeatability. These issues confound the question of whether critical power from the hyperbolic model identifies a threshold of upper body physiological response. Future studies might examine whether one or two single performance tests could provide both valid performance data whilst suggesting changes in aspects of underlying physiology, such as aerobic and anaerobic capacities.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:517580 |
| Date | January 2006 |
| Creators | Taylor, Stuart Andrew |
| Publisher | Teesside University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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