Canadian journal of sport sciences = Journal canadien des sciences du sport最新文献

This study evaluated the blood lactate concentration ([LA-]) response to the Canadian Aerobic Fitness Test (CAFT) in female subjects and compared the strength of prediction of VO2max determined by [LA-] and heart rate (HR). The sample was composed of 98 Canadian Forces females between the ages of 18 and 45 years. The [LA-] after each stage of the step-test was measured in all subjects by sampling blood from the fingertip. VO2max was measured directly during a maximal treadmill run in 66 of these subjects. The results showed that increasing stages of the step-test were associated with increasing [LA-]. The correlation between [LA-] after Stage 5 of the step-test and the directly determined VO2max was r = -0.72 and did not differ significantly from the correlation between HR and VO2max (r = -0.66). The relationship between [LA-] and VO2max for these females was similar to the one established earlier for males; however, the correlation between HR and VO2max for females was different from that observed in males. The present data for the females suggest that [LA-] and HR after Stage 5 of the CAFT predict VO2max equally well for females under age 40.

Whereas short-term cold exposure depletes glycogen reserves, repeated and prolonged moderate exercise in a cold environment creates an energy deficit that is satisfied by an increased metabolism of depot fat. Factors contributing to the fat loss include an exercise-induced hypertrophy of lean tissue, a loss of energy through a cold-induced ketonuria, a stimulation of resting metabolism, increases in the energy cost of movement, and a lower yield of energy per litre of oxygen consumed. Biochemical explanations of the enhanced lipolysis include increased catecholamine secretion, altered sensitivity of catecholamine receptors, and decreases of circulating insulin. The enhanced fat loss with combinations of cold and exercise may be helpful in the therapy of obesity, although the response seems less well developed in women than in men. Moreover, there may be other objections to cold exposure in an older obese population. Short-term glycogen depletion has negative implications for the endurance competitor. Cold acclimation, by favoring an insulative response to cold, reduces glycogen depletion; endurance training may supplement this effect by enhancing the activity of fat-metabolizing enzymes.

A simple ergometer is described that allows highly reproducible plethysmographic measurements of blood flow to be made within 10 seconds of ceasing rhythmic quantitated exercise of the calf muscle. A power output of some 25 Watts is developed with a mechanical efficiency of some 20%. The device seems applicable to a variety of clinical assessments.

Recent studies demonstrated that athletes use more efficient strategies than novices in sports with high perceptual requirements (Abernethy and Russel, 1984; Goulet et al., 1989; Starkes, 1987b). The aim of the present study was to investigate the attentional cost of information processing preceding action in tennis players of different calibers. The dual-task paradigm was used. The primary task consisted of identifying the type of serve (flat, slice, or top-spin) presented on 16-mm file. The secondary task was a manual response to an auditory probe. Results demonstrated that attentional requirements during information processing do not differ between experts and novices. Nevertheless, the experts' results on the primary task are significantly higher than those of novices, whether the primary task is performed alone or simultaneously with the secondary task. The attentional cost of information processed during the ritual phase of the serve is significantly higher than the costs for processing information from the preparation and execution of the serve. It appears, therefore, that attentional input effort is maximal before identification of the most important cues necessary for adequate performance.

Videotapes of the swimming events at the 1988 Seoul Olympics were analyzed to obtain the stroke rate (SR) and stroke length (SL) for each swimmer. In this paper, SR and SL data from the 200-m events were combined with anthropometric data (height and age of the swimmers) and the final time achieved by each swimmer. Statistical analyses were then carried out to determine the relationships among the different variables and their correlation with final times. Differences in performances between male and female swimmers were also investigated. Stroke lengths were found to have high correlations with the final times achieved by the competitors. A strong relationship was also found between height and final time. On an average, the men were found to have a lower stroke rate and to be faster than the women. The latter finding could be a result of the men's longer stroke length and greater height.

The purpose of the present study was to examine the relative contributions of various travel related variables to visiting team success in the National Hockey League. A multiple regression design was used with game outcome as the dependent variable. The independent variables of interest included, as main effects and interactions, number of time zones crossed, direction of travel, distance traveled, preparation/adjustment time, time of season, game number on the road trip, and the home stand. Visiting team success was negatively associated with the interaction of number of time zones crossed and increased preparation time between games, and was positively associated with game number on the road. It was concluded that only a small portion of the variance in the home advantage/visitor disadvantage can be explained by travel related factors.

The present study assessed the capability of the Nautilus leg curl machine to reflect changes in the isokinetic resistance torque offered to the user commensurate with the human torque pattern generated by the knee flexor muscle group. An averaged isokinetic torque pattern was determined from the exercise machine and from a subject pool (N = 20) of physically active men performing prone knee flexion at two angular velocities (30 degrees/s and 60 degrees/s). The torque patterns of the exercise machine and the subject pool were expressed mathematically. Analysis of the linear regression coefficients established that the resistance torque pattern of the exercise machine was not similar to that of the subject pool (p less than .001). It was concluded that the present exercise machine system did not adequately alter the weight-stack load to provide a resistive torque suited to the biomechanical capabilities of the knee flexors under the two isokinetic conditions studied.