Hairul Anuar, Hashim
(2013)
The effects of exercise-induced dehydration
on psychomotor and physiological variables
in relaxation trained army reserved
personnels during prolonged walking in the
heat.
Other.
Pusat Pengajian Sains Perubatan.
(Submitted)
Abstract
Prolonged engagement in the hot environment is common among
military men and women. Inherently, it can lead to fluid losses reaching rates of 1
- 2 L per hour (Coyle, 1994), which can lead to dehydration. A number of studies
have shown that dehydration could lead a drop in performance levels for various
fundamental cognitive-motor abilities (Cian et al., 2000; Cian et al., 2001;
Gopinathan et al., 1988; Nielsen eta/., 1990; Sharma et al., 1986) as well as
physical performance (Terrados & Maughan, 1995). Although dehydration can be
easily prevented by ensuring adequate fluid intake, in some circumstanes, such
as an actual battle, fluid supply may not be readily available. Additional strategy
to sustain mental and physical readiness in such conditions seem desirable.
Relaxation has been used in numerous clinical and non clinical settings such as
clinical, sports, and schools. However, to our knowledge, the effects of relaxation
training on mental performance and physiological parameters in the dehydrated
condition among military personnel have not been studied. Given that soldiers
need to be in an optimal state of physical and mental readiness at all time, the
benefits of relaxation training as a strategy to enhance their mental performance
is worthy of further investigation. The aim of this study is twofold, first, we sought to examine the
effects of dehydration on psychomotor and physiological variables in army
reserved personel and second, to examine the effect of relaxation training in
exercise-induced dehydrated army reserved personnel exercising in the heaf Twenty six reserved army male participated in this study. they were
matched into hydrated and dehydrated groups based on age, V02max. body mass
index, and body fat percentage. Once familiriazed with the experimenal
protocols, they were required to undergo two sessions of 3-hour walking in the
lab-induced hot environment (31°C). In between these two sessions, the subjects
completed an eight sessions of 30-min progressive muscle relaxation training.
Psychomotor performance and blood samples were collected at baseline, and
after every 1 hour of walking in each session. Other parameters (heart rate, V02,
ratings of perceived exertion, rectal temperature) were collected every 20
minutes i nterva I. The results revealed a significantly higher percentage
of body weight loss in the dehydrated group (2.3 ± 1.2%) compared to the
hydrated group (1.1 ± 0.7%). These data demonstrated that consumption of
sufficient fluid during prolonged walking among reserved army personnels is
advisable to avoid the potential adverse effects of dehydration. Significant
differences between the two groups were also found in heart rate and creatine
kinase. No significant differences were found between the two groups in other
parameters. However, there are positive physiological pattern of hydrated group
compared to the dehydrated group. In relation to the relaxation response to
dehydration, it was observed that relaxation training significantly slowed down
the increase in CK value and lowered exercising heart rate. No other parameters
were significant although positive indications of the benefits of relaxation were
observed (eg., lower oxygen consumption). The findings partially support the
notion of that relaxation training is beneficial to moderate the negative effects of
dehydration in male military reserved personnels engaging in prolonged walking
in the heat.
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