European journal of applied physiology
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Eur. J. Appl. Physiol. · Mar 2009
The effect of hyperhydration on physiological and perceived strain during treadmill exercise in personal protective equipment.
Work in personal protective equipment (PPE) impairs thermoregulation causing cardiovascular stress, increased core body temperature, and hypohydration. We examined the effect of pretreating first responders performing treadmill exercise in PPE with an infusion of normal saline on physiological and perceptual strain. Ten (eight males, two females) euhydrated subjects performed treadmill exercise on two occasions wearing a chemical resistant coverall, air purifying respirator, butyl gloves, and heavy boots. ⋯ Exercise duration and maximum core temperature did not differ between euhydrated and hyperhydrated conditions. Perceptual strain index (PeSI) was higher than physiological strain index (PhSI) in the euhydrated condition (P = 0.002) but neither index differed between the control and experimental conditions. Intravenous hyperhydration did not reduce physiological stress, increase exercise, or influence perceptual strain time when compared to the euhydrated condition in moderately fit individuals.
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To evaluate the physiological demands of kitesurfing, ten elite subjects performed an incremental running test on a 400-m track and a 30-min on-water crossing trial during a light crosswind (LW, 12-15 knots). Oxygen uptake (V(O)(2)) was estimated from the heart rate (HR) recorded during the crossing trial using the individual HR-V(O)(2) relationship determined during the incremental test. ⋯ Low values for [La(b)] were observed at the end of crossing trial (2.1 +/- 1.2 mmol l(-1). This first analysis of kitesurfing suggests that the energy demand is mainly sustained by aerobic metabolism during a LW condition.
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Eur. J. Appl. Physiol. · Jan 2009
Reliability of the nociceptive flexor reflex (RIII) threshold and association with Pain threshold.
The purpose of this study was to assess the reliability of the RIII reflex threshold and Pain threshold in three repeated trials using electrocutaneous stimuli. Each trial was separated by a mean of 4.3 +/- 2.9 days (between-trials) and included two repeated measurements (within-trial) of the RIII reflex threshold (RIII-T) and the Pain threshold (PT) separated by 20 min. The participants were 14 healthy males (mean age +/- SD, 23.5 +/- 5.3 years). ⋯ The within-trial CV(SEM) for RIII-T and PT was 5.4 and 4.3%, respectively. There was a significant correlation between the RIII-T threshold and PT. The parallel association and correlation of the RIII-T with the PT suggests that the RIII-T is valid in experimental pain studies under standardised resting conditions.
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Eur. J. Appl. Physiol. · Dec 2008
Resistance exercise increases postexercise oxygen consumption in nonexercising muscle.
This study examined the effect of knee extension resistance exercise on muscle oxygen consumption in nonexercising forearm flexor muscles (nonexV(O)(2mus)) after exercise. Seven healthy male subjects were performed six sets of unilateral knee extension exercise until exhaustion at 40, 60, and 80% of 1 repetition maximum (RM) on separate days. ⋯ NonexV(O)(2mus) returned to the resting values after 1-5 min of recovery and then showed no further significant change for all exercise intensities. This study suggests that knee extension resistance exercise at 40, 60 and 80% 1RM induced an increase in nonexV(O)(2mus) and that the increase of nonexV(O)(2mus) after exercise returned to resting value in several minutes.
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Eur. J. Appl. Physiol. · Nov 2008
Hemodynamic responses to simulated weightlessness of 24-h head-down bed rest and KAATSU blood flow restriction.
The KAATSU training is a unique method of muscle training with restricting venous blood flow, which might be applied to prevent muscle atrophy during space flight, but the effects of KAATSU in microgravity remain unknown. We investigated the hemodynamic responses to KAATSU during actually simulated weightlessness (6 degrees head-down tilt for 24 h, n = 8), and compared those to KAATSU in the seated position before bed rest. KAATSU was applied to the proximal ends of both the thighs. ⋯ NOR, ADH and PRA also increased during KAATSU. These results indicate that KAATSU blood flow restriction reproduces the effects of standing on HR, SV, NOR, ADH, PRA, etc., thus stimulating a gravity-like stress during simulated weightlessness. However, syncope due to lower extremity blood pooling and subsequent reduction of venous return may be induced during KAATSU in microgravity as reported in cases of lower-body negative pressure.