The purpose of this research was to determine the influences of age and habitual physical activity levels on the adjustment to and tolerance of nocturnal shiftwork. Participants included young (mean age 23.4 years) and older (mean age 48.9 years) male shiftworkers who operated on a slow-rotating and backward-rotating shift. Circadian rhythm characteristics were determined for 5 days on each of 3 work-shifts (night, afternoon, morning). Leisure time activity was quantified by means of a questionnaire. Younger subjects had higher amplitudes in their circadian rhythms and adapted more quickly. Active subjects showed a similar trend in rhythm amplitude and adjusted more quickly to nightwork. The older subjects were better suited to the morning shift than their younger counterparts. The observations support a scheduling scheme which takes age (but not necessarily habitual activity level) into account.

The purpose of this study was to establish if short tennis skills transferred to lawn tennis. The experiment was conducted in two parts. In the first experiment 16 children (average age 8.9 years) were coached for 20 h (2 h/day for 2 weeks). The experimental group (n = 8) received 10 h of short tennis coaching followed by 10h of tennis coaching. The control group (n = 8) received tennis coaching only. In the second experiment 14 children (average age 8.5 years) were coached for 8h in group strokes alone (only ground strokes were tested and analysed). The experimental group (n = 7) received 4h of short tennis coaching and 4h of tennis coaching; the control group (n = 7) received tennis coaching only. Prior to coaching, all children were tested on the Dyer Backboard Test. The tests were video-taped for later analysis of technique. The video was analysed by three coaches in terms of backswing, positioning (position where player stood in reference to the bounce of the ball), follow-through, and placement (accuracy with which the ball was hit). The experimental group improved more than the control group on the Dyer Backboard Test (p < 0.05) in Experiment 1. In Experiment 2 both groups improved (p < 0.05) with coaching; there was no difference (p > 0.05) between the two groups following coaching. This implied that the short tennis skills positively transferred to tennis.(ABSTRACT TRUNCATED AT 250 WORDS)

Three investigations were carried out to examine the concurrent validity and the reliability of a portable dynamometer (Takei Kiki Kogyo) for the measurement of back and leg strength. First, leg extension strength of 19 subjects was measured using the Takei dynamometer and compared to the isometric knee extension strength of the dominant (right) leg measured using a computer-controlled dynamometer (Lido Active, Davis, CA). The back extension strength of 18 subjects was also compared between the two dynamometers. Second, back and leg strengths of 36 subjects, aged 19-30 years, were measured twice using the Takei dynamometer. Six days separated the test and retest. Third, back and leg strengths of four subjects, aged 21-30 years, were measured at six different times of the solar day. Significant relations (p < 0.001) were obtained between the Takei and Lido dynamometers for leg strength (r = 0.90) and back strength (r = 0.79). Significant test-retest correlations (p < 0.001) were found for leg strength (r = 0.80) and back strength (r = 0.91). Group mean (+/- SD) leg strength values of test (1450.4 +/- 428.6 N) and retest (1432.8 +/- 449.1 N) did not differ ((p > 0.05). A small (4.5%) but significant difference was found between the test (1057.2 +/- 309.9 N) and retest (1106.2 +/- 334.4 N) mean values for back strength (p < 0.05). A time of day effect was evident for back and leg strength (p < 0.05); on average the peak times occurred at 16:53 h and 18:20 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

This study aimed to describe the work-rate profiles of referees during soccer matches and record heart-rate responses during these games. Using video-recordings 14 referees were observed and their heart rates during the games were monitored by short-range radio telemetry. These included 11 football league matches. The exercise intensity was largely submaximal with a change in activity every 6 s. The mean distance covered during the game was 9.44 km; a significant fall in work rate was noted in the second half (P < 0.05). The mean heart rate of 165 beats min 1 did not vary between first and second halves. The work rate and heart rate varied more between individuals than with the importance of the match, but this variation was small. It was considered that refereeing top level soccer places high physiological demands on the official. This has implications for training and fitness assessment.

This study compared circadian rhythms in physiological, subjective, and performance measures between groups exhibiting different levels of habitual physical activity. Fourteen male subjects, aged 19-29 years, were assigned to a physically active (group I, n = 7) or a physically inactive (group II, n = 7) group on the basis of leisure-time physical activity. Rectal temperature, oral temperature, resting pulse rate, subjective arousal and sleepiness were measured at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 in a counter-balanced sequence for each subject. Whole-body flexibility, back and leg strength, grip strength (right and left), flight time in a vertical jump, PWC150, and self-chosen work-rate were also recorded at each time point. At least 8h separated each test session. Subjects avoided exercise 48h prior to, and during the experiment. Data were subjected to the group cosinor method. Group I evidenced 1.5-2.5 times greater rhythm amplitudes than Group II for oral temperature, subjective arousal, sleepiness, flexibility, left and right grip strength, submaximal heart rate, and self-chosen work-rate (p<0.05). Oral temperature and arousal for Group I were lower than Group II only at 06:00. Early morning troughs in most of the performance measures were significantly greater for Group I (p<0.05). The groups did not differ with respect to phasing of the rhythms (p<0.05). These results confirm with physical performance measures that rhythm amplitudes are higher for physically fit subjects. This could be attributed to greater early-morning troughs in the measures for active individuals. Since the subjects were sedentary immediately prior to testing, it is plausible that these findings are training effects of physical activity.

For 26 men anthropometric measures were not significantly correlated with broad jump performance. Broad jump performance, however, was correlated .56 with peak torque during fast isokinetic action but not at all with slow action.