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Volume 16 , Issue 6
Showing 1-4 articles out of 4 articles from the selected issue
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ORIGINALS
  • Qiuqing Geng, Kalev Kuklane, Ingvar Holmér
    Volume 16 (1997) Issue 6 Pages 229-236
    Released: September 28, 2001
    JOURNALS FREE ACCESS
    In this study, tactile sensitivity of gloved hand in the cold operation has been investigated. The relations among physical properties of protective gloves and hand tactile sensitivity and cold protection were also analysed both objectively and subjectively. Subjects with various gloves participated in the experimental study during cold exposure at different ambient temperatures of -12°C and -25°C. Tactual performance was measured using an identification task with various sizes of objects over the percentage of misjudgment. Forearm, hand and finger skin temperatures were also recorded throughout. The experimental data were analysed using analysis of variance (ANOVA) model and the Tukey's multiple range test. The results obtained indicated that the tactual performance was affected both by gloves and by hands/fingers cooling. Effect of object size on the tactile discrimination was significant and the misjudgment increased when similar sizes of objects were identified, especially at -25°C.
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  • Martin Hexamer, Jürgen Werner
    Volume 16 (1997) Issue 6 Pages 237-247
    Released: September 28, 2001
    JOURNALS FREE ACCESS
    This paper describes an automatic control concept for liquid cooling garments. The concept consists of an own controller for mean skin temperature whose setpoint is either fixed or adjusted to the metabolic heat production by means of the heart rate signal. The controller for mean skin temperature included both a proportional and an integral signal path (PI-type), the latter being able to eliminate any load error within the control loop. This means that the actual skin temperature will always match the given setpoint irrespective of the amount and the origin of the heat gain at the body shell. Experiments were carried out to test the operation of the skin temperature controller. There the setpoint was fixed while metabolic heat production was changing. After a transient period with deviations, the load error was always eliminated by the skin temperature controller. With this result one can also imagine the controllers ability to compensate changing heat gains from the environment. Despite this behaviour, the amount of heat removal was not high enough to prevent sweating and warm discomfort during all exercise levels. Therefore we draw the conclusion that, in addition, the setpoint of the skin temperature should be adjusted to the metabolic rate/heat production. A convenient physiological signal that reflects the current level of metabolic rate is the heart rate signal. After being filtered the heart rate signal was used during some experiments to change the setpoint of the skin temperature controller. The reason for this filtering (lowpass, time constant = 10 min) was, firstly, the necessity of attenuating the consequences of short-term psychological effects on the heart rate and secondly, the avoidance of vasoconstriction due to too fast changes of the exercise/heart rate induced cooling rate. In the following experiments it became clear that the adjustment of the skin temperature setpoint to the exercise level was an improvement as there was less sweating and the subjects felt more comfortable.
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  • Takafumi Maeda, Akira Yasukouchi
    Volume 16 (1997) Issue 6 Pages 249-255
    Released: September 28, 2001
    JOURNALS FREE ACCESS
    The purpose of this study is to evaluate effects of breathing hyperoxic gas on blood lactate disappearance after submaximal exercise in two different physical fitness groups and to clarify the most effective oxygen concentration in each group. Fourteen healthy male students participated as subjects in this study. They were divided in two groups by difference in their anaerobic threshold (AT). Seven males were treated as Higher AT group and the others as Lower AT group. Subjects wore a T-shirt, short pants and sports shoes and performed three sessions; each consisting of five minutes of exercise and six minutes of rest, at a workload of 70% VO2max On a bicycle ergometer. Hyperoxic gas was breathed only during recovery periods. Oxygen rates of 21, 30, 40, 60, 80 and 100% in inspired gas were employed. According to the results of blood lactate (BLA), the most effective oxygen condition on BLA disappearance was obtained over 60% in Higher AT group and at 30% oxygen in Lower AT group. Thus, it was especially noteworthy that the effects of hyperoxic gas in Higher AT group were different from those of Lower AT group. It is thought that the effects of breathing hyperoxic gas were dependent on physical fitness, which have caused many reports to be in conflict hitherto.
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  • Toshihiko Tsutsumi, Brian M. Don, Leonard D. Zaichkowsky, Laura L. Del ...
    Volume 16 (1997) Issue 6 Pages 257-266
    Released: September 28, 2001
    JOURNALS FREE ACCESS
    Previous studies concerning psychological benefits of exercise among the elderly has focused predominantly on the effects of aerobic exercise. In the present study, psychological and behavioral adaptations in response to 12-weeks of strength training were examined in medically healthy but sedentary 42 older adults (mean age=68 years). The purpose of this study was to evaluate the effects of high and low intensity resistance training intensity on a) muscular fitness, b) psychological affect, and c) neurocognitive functioning. Subjects were randomly assigned to high intensity/low volume (EXH: 2 sets of 8 to 10 repetitions for 75 to 85% of 1 RM), low intensity/high volume (EXL: 2 sets of 14 to 16 repetitions for 55 to 65% of 1 RM), or no exercise control programs. Prior to and following the 12-week program, subjects underwent comprehensive physiological and psychological evaluations. Physiological assessment included measurements of blood pressure, heart rate, arm and leg muscle strength, body composition, and oxygen consumption (VO2max). Psychological measures included evaluations of mood, anxiety, and physical self-efficacy as well as cognitive functioning. The results of this study indicated that both high and low intensity strength programs were associated with marked improvements in physiological fitness and psychological functioning. Specifically, subjects in the strength training programs increased overall muscle strength by 38.6% and reduced percent body fat by 3.0%. Favorable psychological changes in the strength-trained subjects included improvements in positive and negative mood, trait anxiety, and perceived confidence for physical capability. The treatment effects of neurocognitive functioning were not significant. In summary, this study demonstrated that participation in 12-weeks of high or low intensity strength training can improve overall physical fitness, mood, and physical self-efficacy in older adults while cognitive functioning remains constant.
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