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1.
Post-exercise cooling techniques in hot,humid conditions 总被引:1,自引:0,他引:1
Martin James Barwood Sarah Davey James R. House Michael J. Tipton 《European journal of applied physiology》2009,107(4):385-396
Major sporting events are often held in hot and humid environmental conditions. Cooling techniques have been used to reduce
the risk of heat illness following exercise. This study compared the efficacy of five cooling techniques, hand immersion (HI),
whole body fanning (WBF), an air cooled garment (ACG), a liquid cooled garment (LCG) and a phase change garment (PCG), against
a natural cooling control condition (CON) over two periods between and following exercise bouts in 31°C, 70%RH air. Nine males
[age 22 (3) years; height 1.80 (0.04) m; mass 69.80 (7.10) kg] exercised on a treadmill at a maximal sustainable work intensity
until rectal temperature (T
re) reached 38.5°C following which they underwent a resting recovery (0–15 min; COOL 1). They then recommenced exercise until
T
re again reached 38.5°C and then undertook 30 min of cooling with (0–15 min; COOL 2A), and without face fanning (15–30 min;
COOL 2B). Based on mean body temperature changes (COOL 1), WBF was most effective in extracting heat: CON 99 W; WBF: 235 W;
PCG: 141 W; HI: 162 W; ACG: 101 W; LCG: 49 W) as a consequence of evaporating more sweat. Therefore, WBF represents a cheap
and practical means of post-exercise cooling in hot, humid conditions in a sporting setting. 相似文献
2.
A previous study by the authors using a heated thermal manikin showed that the cooling rates of phase change material (PCM)
are dependent on temperature gradient, mass, and covering area. The objective of this study was to investigate if the cooling
effects of the temperature gradient observed on a thermal manikin could be validated on human subjects in extreme heat. The
subjects wore cooling vests with PCMs at two melting temperatures (24 and 28°C) and fire-fighting clothing and equipment,
thus forming three test groups (vest24, vest28 and control group without the vest). They walked on a treadmill at a speed
of 5 km/h in a climatic chamber (air temperature = 55°C, relative humidity = 30%, vapour pressure = 4,725 Pa, and air velocity = 0.4 m/s).
The results showed that the PCM vest with a lower melting temperature (24°C) has a stronger cooling effect on the torso and
mean skin temperatures than that with a higher melting temperature (28°C). Both PCM vests mitigate peak core temperature increase
during the resting recovery period. The two PCM vests tested, however, had no significant effect on the alleviation of core
temperature increase during exercise in the heat. To study the possibility of effective cooling of core temperature, cooling
garments with PCMs at even lower melting temperatures (e.g. 15°C) and a larger covering area should be investigated. 相似文献
3.
Short term effects of various water immersions on recovery from exhaustive intermittent exercise 总被引:2,自引:0,他引:2
Pournot H Bieuzen F Duffield R Lepretre PM Cozzolino C Hausswirth C 《European journal of applied physiology》2011,111(7):1287-1295
In order to investigate the effectiveness of different techniques of water immersion recovery on maximal strength, power and
the post-exercise inflammatory response in elite athletes, 41 highly trained (Football, Rugby, Volleyball) male subjects (age = 21.5 ± 4.6 years,
mass = 73.1 ± 9.7 kg and height = 176.7 ± 9.7 cm) performed 20 min of exhaustive, intermittent exercise followed by a 15 min
recovery intervention. The recovery intervention consisted of different water immersion techniques, including: temperate water
immersion (36°C; TWI), cold water immersion (10°C; CWI), contrast water temperature (10–42°C; CWT) and a passive recovery
(PAS). Performances during a maximal 30-s rowing test (P30 s), a maximal vertical counter-movement jump (CMJ) and a maximal isometric voluntary contraction (MVC) of the knee extensor
muscles were measured at rest (Pre-exercise), immediately after the exercise (Post-exercise), 1 h after (Post 1 h) and 24 h
later (Post 24 h). Leukocyte profile and venous blood markers of muscle damage (creatine kinase (CK) and lactate dehydrogenase
(LDH)) were also measured Pre-exercise, Post 1 h and Post 24 h. A significant time effect was observed to indicate a reduction
in performance (Pre-exercise vs. Post-exercise) following the exercise bout in all conditions (P < 0.05). Indeed, at 1 h post exercise, a significant improvement in MVC and P30 s was respectively observed in the CWI and CWT groups compared to pre-exercise. Further, for the CWI group, this result was
associated with a comparative blunting of the rise in total number of leucocytes at 1 h post and of plasma concentration of
CK at 24 h post. The results indicate that the practice of cold water immersion and contrast water therapy are more effective
immersion modalities to promote a faster acute recovery of maximal anaerobic performances (MVC and 30″ all-out respectively)
after an intermittent exhaustive exercise. These results may be explained by the suppression of plasma concentrations of markers
of inflammation and damage, suggesting reduced passive leakage from disrupted skeletal muscle, which may result in the increase
in force production during ensuing bouts of exercise. 相似文献
4.
James R. House Heather C. Lunt Rowan Taylor Gemma Milligan Jason A. Lyons Carol M. House 《European journal of applied physiology》2013,113(5):1223-1231
Cooling vests (CV) are often used to reduce heat strain. CVs have traditionally used ice as the coolant, although other phase-change materials (PCM) that melt at warmer temperatures have been used in an attempt to enhance cooling by avoiding vasoconstriction, which supposedly occurs when ice CVs are used. This study assessed the effectiveness of four CVs that melted at 0, 10, 20 and 30 °C (CV0, CV10, CV20, and CV30) when worn by 10 male volunteers exercising and then recovering in 40 °C air whilst wearing fire-fighting clothing. When compared with a non-cooling control condition (CON), only the CV0 and CV10 vests provided cooling during exercise (40 and 29 W, respectively), whereas all CVs provided cooling during resting recovery (CV0 69 W, CV10 66 W, CV20 55 W and CV30 29 W) (P < 0.05). In all conditions, skin blood flow increased when exercising and reduced during recovery, but was lower in the CV0 and CV10 conditions compared with control during exercise (observed power 0.709) (P < 0.05), but not during resting recovery (observed power only 0.55). The participants preferred the CV10 to the CV0, which caused temporary erythema to underlying skin, although this resolved overnight after each occurrence. Consequently, a cooling vest melting at 10 °C would seem to be the most appropriate choice for cooling during combined work and rest periods, although possibly an ice-vest (CV0) may also be appropriate if more insulation was worn between the cooling packs and the skin than used in this study. 相似文献
5.
Sigitas Kamandulis Albertas Skurvydas Marius Brazaitis Laimutis Škikas Jacques Duchateau 《European journal of applied physiology》2010,108(6):1065-1074
The aim of this study was to compare the possible changes in muscle activation level between a first and second bout of damaging
eccentric exercise performed at 2 weeks interval (i.e. repeated bout effect). To that purpose, ten physically active males
took part in this study. The eccentric exercise consisted of 10 sets of 12 maximal voluntary contractions (MVC) produced by
the knee extensors during movements performed at a constant speed of 160°s−1. Changes in voluntary and electrically evoked torque in concentric and/or isometric conditions were assessed at the following
time points: pre-exercise, and 2 min, 1 and 24 h after each eccentric exercise. At the same time points, voluntary activation
was quantified by the superimposed electrical stimulation technique. Muscle soreness and plasma CK activity were measured
within 48 h after the eccentric exercise. The results showed that the decrease in eccentric peak torque was linear throughout
the exercise protocol. At the end of bouts 1 and 2, torque was significantly reduced by 27.7 ± 9.1 and 23.4 ± 11.2, respectively,
with no difference between bouts (P > 0.05). At 24 h post-exercise, a lower reduction (P < 0.05) in MVC (17.8 ± 5.4%) and electrically evoked (16.7 ± 4.6%) isometric torque was observed for bout 2. In contrast,
no statistical difference was found in the deficit in voluntary activation between the two bouts. In conclusion, our results
indicate that the repeated bout effect of eccentric exercise appears to reduce muscle damage, but does not influence the level
of voluntary activation. 相似文献
6.
We examined whether a prior bout of eccentric exercise in the elbow flexors provided protection against exercise-induced muscle
damage in the contralateral arm. Fifteen males (age 22.7 ± 2.1 years; height 178.6 ± 6.8 cm, mass 75.8 ± 9.3 kg) were randomly
assigned to two groups who performed two bouts of 60 eccentric contractions (30°/s) separated by 2 weeks: ipsilateral (n = 7, both bouts performed in the same arm), contralateral (n = 8, one bout performed in each arm). Strength, muscle soreness and resting arm angle (RAA) were measured at baseline and
at 1, 24 and 48 h post exercise. Surface electromyography was recorded during both bouts of exercise. The degree of strength
loss was attenuated (p < 0.05) in the ipsilateral group after the second bout of eccentric exercise (−22 cf. −3% for bout 1 and 2 at 24 h, respectively).
Strength loss following eccentric exercise was also attenuated (p < 0.05) at 24 h in the contralateral group (−30 cf. 13% for bout 1 and 2, respectively). Muscle soreness (≈34 cf 19 mm) and
change in RAA (≈5 cf. 3%) were also lower following the second bout of eccentric exercise (p < 0.05), although there was no difference in the overall change in these values between groups. Median frequency (MF) was
decreased by 31% between bouts, with no difference between groups. Data support observations that the repeated bout effect
transfers to the opposite (untrained) limb. The similar reduction in MF between bouts for the two groups provides evidence
for a centrally mediated, neural adaptation. 相似文献
7.
Trevor C. Chen Hsin-Lian Chen Ming-Ju Lin Chang-Jun Wu Kazunori Nosaka 《European journal of applied physiology》2009,106(2):267-275
Since little is known about the repeated bout effect of more than two eccentric exercise bouts, this study compared muscle
damage responses among four exercise bouts. Fifteen young (21.8 ± 1.9 years) men performed four bouts of 30 maximal isokinetic
eccentric contractions of the elbow flexors every 4 weeks. Maximal voluntary elbow flexion isometric and concentric strength,
range of motion at the elbow joint (ROM), upper arm circumference, blood markers of muscle damage, and muscle soreness were
measured before and up to 120 h following each bout. Changes in all measures following the second to fourth bouts were significantly
(P < 0.05) smaller than those after the first bout. The decreases in strength and ROM immediately after the fourth bout were
significantly (P < 0.05) smaller than other bouts. It is concluded that the first bout confers the greatest adaptation, but further adaptation
is induced when the exercise is repeated more than three times. 相似文献
8.
The influence of cold water immersions on adaptation following a single bout of damaging exercise 总被引:1,自引:0,他引:1
Glyn Howatson S. Goodall K. A. van Someren 《European journal of applied physiology》2009,105(4):615-621
The aim of this investigation was to elucidate the effects of cold water immersions (CWIs) following damaging exercise on
the repeated bout effect (RBE). Sixteen males performed two bouts of drop jump exercise separated by 14–21 days. Participants
were equally, but randomly assigned to either a CWI (12-min CWI at 15°C) or control group (12-min seated rest). Treatments
were given immediately after the first exercise bout, 24, 48 and 72 h post-exercise. No interventions were given following
the second bout. Maximum voluntary contraction (MIVC), soreness (DOMS), creatine kinase (CK), thigh girth and range of motion
(ROM) were recorded before and for 96 h following the initial and repeated bouts of damaging exercise. All variables, except
ROM, showed a significant time effect (P < 0.01) indicating the presence of muscle damage following the initial bout; there were no differences between the CWI and
control groups after the initial bout. Following the repeated bout of exercise there was a significant attenuation in the
reduction of MIVC (P = 0.002) and a reduction in DOMS (P < 0.001), which is indicative of the RBE. There were no significant differences between groups following the repeated bout
of damaging exercise. These data show that CWI had no effect following damaging exercise and did not inhibit the RBE. Despite
CWI being used routinely, its efficacy remains unclear and there is a need to elucidate the benefits of this intervention
on recovery and adaptation to provide practitioners with evidence based practice. 相似文献
9.
Abdulaziz Aldayel Marc Jubeau Michael R. McGuigan Kazunori Nosaka 《European journal of applied physiology》2010,108(4):709-717
This study compared the first and second exercise bouts consisting of electrically evoked isometric contractions for muscle damage profile. Nine healthy men (31 ± 4 years) had two electrical muscle stimulation (EMS) bouts separated by 2 weeks. The knee extensors of one leg were stimulated by biphasic rectangular pulses (75 Hz, 400 μs, on–off ratio 5–15 s) at the knee joint angle of 100° (0°, full extension) to induce 40 isometric contractions, while the current amplitude was increased to maintain maximal force generation. Maximal voluntary isometric contraction (MVC) torque of the knee extensors at 100°, muscle soreness, pressure pain threshold and plasma creatine kinase (CK) activity were used as indirect markers of muscle damage, and measured before and 1, 24, 48, 72 and 96 h after EMS bout, and the changes over time were compared between bouts. The torque produced during exercise was approximately 30% of MVC, and no significant difference between bouts was evident for the changes in peak and average torque over 40 contractions. MVC decreased significantly (P < 0.05) by 26% immediately and 1 h after both bouts, but the recovery was significantly (P < 0.05) faster after the second bout (100% at 96 h) compared with the first bout (81% at 96 h). Development of muscle soreness and tenderness, and increases in plasma CK activity were significantly (P < 0.05) smaller after the second than the first bout. These results show that changes in muscle damage markers were attenuated in the second EMS bout compared with the initial EMS bout. 相似文献
10.
Jamie Stanley Michael Leveritt Jonathan M. Peake 《European journal of applied physiology》2010,110(6):1163-1173
We compared the effects of an ice-slush beverage (ISB) and a cool liquid beverage (CLB) on cycling performance, changes in
rectal temperature (T
re) and stress responses in hot, humid conditions. Ten trained male cyclists/triathletes completed two exercise trials (75 min
cycling at ~60% peak power output + 50 min seated recovery + 75% peak power output × 30 min performance trial) on separate
occasions in 34°C, 60% relative humidity. During the recovery phase before the performance trial, the athletes consumed either
the ISB (mean ± SD −0.8 ± 0.1°C) or the CLB (18.4 ± 0.5°C). Performance time was not significantly different after consuming
the ISB compared with the CLB (29.42 ± 2.07 min for ISB vs. 29.98 ± 3.07 min for CLB, P = 0.263). T
re (37.0 ± 0.3°C for ISB vs. 37.4 ± 0.2°C for CLB, P = 0.001) and physiological strain index (0.2 ± 0.6 for ISB vs. 1.1 ± 0.9 for CLB, P = 0.009) were lower at the end of recovery and before the performance trial after ingestion of the ISB compared with the
CLB. Mean thermal sensation was lower (P < 0.001) during recovery with the ISB compared with the CLB. Changes in plasma volume and the concentrations of blood variables
(i.e., glucose, lactate, electrolytes, cortisol and catecholamines) were similar between the two trials. In conclusion, ingestion
of ISB did not significantly alter exercise performance even though it significantly reduced pre-exercise T
re compared with CLB. Irrespective of exercise performance outcomes, ingestion of ISB during recovery from exercise in hot humid
environments is a practical and effective method for cooling athletes following exercise in hot environments. 相似文献
11.
<Emphasis Type="Italic">V</Emphasis>O<Subscript>2</Subscript>max during successive maximal efforts 总被引:1,自引:0,他引:1
Foster C Kuffel E Bradley N Battista RA Wright G Porcari JP Lucia A deKoning JJ 《European journal of applied physiology》2007,102(1):67-72
The concept of VO2max has been a defining paradigm in exercise physiology for >75 years. Within the last decade, this concept has been both
challenged and defended. The purpose of this study was to test the concept of VO2max by comparing VO2 during a second exercise bout following a preliminary maximal effort exercise bout. The study had two parts. In Study #1,
physically active non-athletes performed incremental cycle exercise. After 1-min recovery, a second bout was performed at
a higher power output. In Study #2, competitive runners performed incremental treadmill exercise and, after 3-min recovery,
a second bout at a higher speed. In Study #1 the highest VO2 (bout 1 vs. bout 2) was not significantly different (3.95 ± 0.75 vs. 4.06 ± 0.75 l min−1). Maximal heart rate was not different (179 ± 14 vs. 180 ± 13 bpm) although maximal V
E was higher in the second bout (141 ± 36 vs. 151 ± 34 l min−1). In Study #2 the highest VO2 (bout 1 vs. bout 2) was not significantly different (4.09 ± 0.97 vs. 4.03 ± 1.16 l min−1), nor was maximal heart rate (184 + 6 vs. 181 ± 10 bpm) or maximal V
E (126 ± 29 vs. 126 ± 34 l min−1). The results support the concept that the highest VO2 during a maximal incremental exercise bout is unlikely to change during a subsequent exercise bout, despite higher muscular
power output. As such, the results support the “classical” view of VO2max. 相似文献
12.
Castle PC Maxwell N Allchorn A Mauger AR White DK 《European journal of applied physiology》2012,112(1):377-385
We used incorrect visual feedback of ambient and core temperature in the heat to test the hypothesis that deception would
alleviate the decrement in cycling performance compared to a no deception trial. Seven males completed three 30 min cycling
time trials in a randomised order on a Kingcycle ergometer. One time trial was in temperate, control conditions (CON: 21.8 ± 0.6°C;
43.3 ± 4.3%rh), the others in hot, humid conditions (HOT: 31.4 ± 0.3°C; 63.9 ± 4.5%rh). In one of the hot, humid conditions
(31.6 ± 0.5°C; 65.4 ± 4.3%rh), participants were deceived (DEC) into thinking the ambient conditions were 26.0°C; 60.0%rh
and their core temperature was 0.3°C lower than it really was. Compared to CON (16.63 ± 2.43 km) distance covered was lower
in HOT (15.88 ± 2.75 km; P < 0.05), but DEC ameliorated this (16.74 ± 2.87 km; P < 0.05). Mean power output was greater in DEC (184.4 ± 60.4 W) than HOT (168.1 ± 54.1 W; P < 0.05) and no difference was observed between CON and DEC. Rectal temperature and iEMG of the vastus lateralis were not
different, but RPE in the third minute was lower in DEC than HOT (P < 0.05). Deception improved performance in the heat by creating a lower RPE, evidence of a subtle mismatch between the subconscious
expectation and conscious perception of the task demands. 相似文献
13.
Craig A. Goodman Alan Hayes Michael J. McKenna 《European journal of applied physiology》2009,105(4):575-583
This study investigated whether high frequency in vitro stimulation of rat fast-twitch extensor digitorum longus muscle depresses
Na+, K+-ATPase (NKA) activity as measured by the maximal in vitro 3-O-MFPase assay. EDL muscles subjected to 10 s continuous 100 Hz
stimulation reduced tetanic force by 51.8 ± 5.1% which recovered to 81.2 ± 6.1% after 1 min and remained stable over 1 h recovery
period. A second bout reduced force by 50.3 ± 3.8% of initial but had no effect on 3-O-MFPase activity. Three minutes of intermittent
stimulation (1 s at 100 Hz and 4 s recovery) resulted in 87.0 ± 2.8% decline force with slow recovery (62.7 ± 5.8% of initial
after 1 h). The second 3-min bout reduced force by 83.3 ± 3.6% of initial with no change in maximal 3-O-MFPase activity. These
findings contrast previous human studies where fatiguing voluntary exercise depresses maximal NKA activity. This suggests
that NKA in rat fast-twitch muscle is resistant to fatigue-induced inactivation under these conditions. Furthermore, the loss
of force with fatigue was not related to depressed maximal NKA activity. 相似文献
14.
Juan Del Coso Nassim Hamouti Roberto Aguado-Jimenez Ricardo Mora-Rodriguez 《European journal of applied physiology》2010,108(3):523-532
To determine which active-recovery protocol would reduce faster the high blood H+ and lactate concentrations produced by repeated bouts of high-intensity exercise (HIE). On three occasions, 11 moderately
trained males performed 4 bouts (1.5 min) at 163% of their respiratory compensation threshold (RCT) interspersed with active-recovery:
(1) 4.5 min pedalling at 24% RCT (SHORT); (2) 6 min at 18% RCT (MEDIUM); (3) 9 min at 12% RCT (LONG). The total work completed during recovery was the same in all three trials. Respiratory gases and arterialized-blood samples
were obtained during exercise. At the end of exercise, LONG in comparison to SHORT and MEDIUM increased plasma pH (7.32 ± 0.02 vs. ~7.22 ± 0.03; P < 0.05), while reduced lactate concentration (8.5 ± 0.9 vs. ~10.9 ± 0.8 mM; P < 0.05). Ventilatory equivalent for CO2 was higher in LONG than SHORT and MEDIUM (31.4 ± 0.5 vs. ~29.6 ± 0.5; P < 0.05). Low-intensity prolonged recovery between repeated bouts of HIE maximized H+ and lactate removal likely by enhancing CO2 unloading. 相似文献
15.
Exercise modality modulates body temperature regulation during exercise in uncompensable heat stress
Schlader ZJ Raman A Morton RH Stannard SR Mündel T 《European journal of applied physiology》2011,111(5):757-766
This study evaluated exercise modality [i.e. self-paced (SP) or fixed-intensity (FI) exercise] as a modulator of body temperature
regulation under uncompensable heat stress. Eight well-trained male cyclists completed (work-matched) FI and SP cycling exercise
bouts in a hot (40.6 ± 0.2°C) and dry (relative humidity 23 ± 3%) environment estimated to elicit 70% of [(V)\dot] \dot{V} O2max. Exercise intensity (i.e. power output) decreased over time in SP, which resulted in longer exercise duration (FI 20.3 ± 3.4 min,
SP 23.2 ± 4.1 min). According to the heat strain index, the modification of exercise intensity in SP improved the compensability
of the thermal environment which, relative to FI, was likely a result of the reductions in metabolic heat production (i.e.
[(V)\dot] \dot{V} O2). Consequently, the rate of rise in core body temperature was higher in FI (0.108 ± 0.020°C/min) than in SP (0.082 ± 0.016°C/min).
Interestingly, cardiac output, stroke volume, and heart rate during exercise were independent of exercise modality. However,
core body temperature (FI 39.4 ± 0.3°C, SP 39.1 ± 0.4°C), blood lactate (FI 2.9 ± 0.8 mmol/L, SP 2.3 ± 0.7 mmol/L), perceived
exertion (FI 18 ± 2, SP 16 ± 2), and physiological strain (FI 9.1 ± 0.9, SP 8.3 ± 1.1) were all higher in FI compared to SP
at exhaustion/completion. These findings indicate that, when exercise is SP, behavioral modification of metabolic heat production
improves the compensability of the thermal environment and reduces thermoregulatory strain. Therefore, under uncompensable
heat stress, exercise modality modulates body temperature regulation. 相似文献
16.
Michael J. Buono Nanette V. L. Lee Paul W. Miller 《The journal of physiological sciences : JPS》2010,60(2):103-107
The purpose of this study was to determine the effect of increases in exercise intensity on the sweat lactate concentration
and lactate excretion rate. Eight healthy male volunteers complete a 90-min exercise bout of treadmill walking in a 35°C and
40% relative humidity environmental chamber. During the exercise trial, the subjects performed three 30-min ordered exercise
bouts at 60, 70, and 80% of their age-predicted maximum heart rate (HRmax), with 10 min of rest outside the chamber between bouts. Sweat rate was measured volumetrically during each of the three
exercise bouts on the flexor surface of the proximal half of the right forearm. Sweat lactate concentration ([lactate]sweat) was measured in each sample and multiplied by the forearm sweat rate to calculate the lactate excretion rate (LER). There
was a significant (P < 0.05) decrease in the [lactate]sweat at the 70 and 80% HRmax exercise intensities compared to the 60% HRmax exercise intensity. Conversely, the LER increased significantly at the highest two exercise intensities compared to the 60%
HRmax exercise intensity. Such data suggest that increases in exercise intensity require an increase in lactate production, as
measured by the LER. Furthermore, the decreased [lactate]sweat at the higher exercise intensities is most likely the result of increased sweat production causing a dilution effect on the
[lactate]sweat, thus limiting its ability to accurately indicate the metabolic activity of the sweat gland. 相似文献
17.
Davis JK Bishop PA Zhang Y Matt Green J Casaru C Orrick KD Curtner-Smith M Richardson MT Schumacker RE 《European journal of applied physiology》2012,112(2):725-734
This study examined heat stress, heart rate (HR), fluid balance, micro-environment temperature and humidity with Islamic athletic
clothing (IC) compared to traditional soccer uniform (SC). Ratings of perceived exertion (RPE), session RPE (S-RPE), comfort,
and cooling response were also examined. Female volunteers (N = 8) completed a treadmill
[(V)\dot]\textO2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} test and then, in a randomized, counter-balanced order, two intermittent running bouts (45 min total) in a hot environment
(30.0°C WBGT) in IC and SC. Thereafter, participants sat for 40 min in the hot ambient environment. Repeated measures ANOVA
revealed significantly greater micro-environment temperature (p = 0.02) (IC 33.3 ± 3.2°C, SC 32.0 ± 2.8°C) and humidity (p = 0.04) (IC 48.4 ± 8.1%, SC 42.9 ± 7.9%) in IC during the exercise trial but no difference in the 40-min recovery period
for micro-environment temperature (p = 0.25) or humidity (p = 0.18). No significant difference (p > 0.05) was shown for core temperature (T
rec) (IC 38.3 ± 0.4°C, SC 38.2 ± 0.4°C), HR (IC l54 ± 28 beats min−1, SC 151 ± 26 beats min−1) or RPE (IC 4.7 ± 2.1, SC 3.8 ± 1.7) during the exercise trial or recovery period. Results from a paired t test revealed a significantly greater (p < 0.05) S-RPE (IC 5.8 ± 1.2, SC 4.3 ± 1.9), sweat loss (IC 1.4 ± 0.4 L h−1, SC 1.2 ± 0.4 L h−1) and greater discomfort during the exercise and recovery period for the IC. IC clothing appears to have no detrimental effects
on heat storage or heat strain during exercise or recovery. 相似文献
18.
Force and EMG signal patterns during repeated bouts of concentric or eccentric muscle actions 总被引:11,自引:0,他引:11
P A Tesch G A Dudley M R Duvoisin B M Hather R T Harris 《Acta physiologica Scandinavica》1990,138(3):263-271
Healthy males (n = 14) performed three bouts of 32 unilateral, maximal voluntary concentric (CON) or eccentric (ECC) quadriceps muscle actions on separate days. Surface electromyography (EMG) of the m. vastus lateralis (VL) and m. rectus femoris (RF) and torque were measured. Integrated EMG (IEMG), mean (MPF) and median power frequencies and torque were averaged for seven separate blocks of four consecutive muscle actions. Torque was greater (P less than 0.05) for ECC than for CON muscle actions at the start of exercise. It did not decline throughout ECC exercise, but decreased (P less than 0.05) markedly for each bout and over bouts of CON exercise. Thus, torque overall was substantially greater (P less than 0.05) for ECC than for CON exercise. At the start of exercise IEMG of VL or RF was greater (P less than 0.05) for CON than for ECC muscle actions. This was also true for overall IEMG activity during exercise. The IEMG increased (P less than 0.05) modestly for both muscles during each bout of CON or ECC muscle actions, but did not change for the VL over bouts. The IEMG of RF decreased (P less than 0.05) modestly over CON but not ECC exercise bouts. At the beginning of the first bout of exercise the IEMG/torque ratio was twofold greater (P less than 0.05) for CON than ECC muscle actions. The ratio of IEMG/torque increased (P less than 0.05) markedly during CON but did not change during ECC exercise. Thus, by the end of the third bout there was a fivefold difference (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
19.
Effect of contrast water therapy duration on recovery of cycling performance: a dose�Cresponse study
This study investigated whether contrast water therapy (CWT) has a dose?Cresponse effect on recovery from high-intensity cycling. Eleven trained male cyclists completed four trials, each commencing with a 75-min cycling protocol containing six sets of five 15-s sprints and three 5-min time-trials in thermoneutral conditions. Ten minutes post-exercise, participants performed one of four recovery protocols: CWT for 6?min (CWT6), 12?min (CWT12), or 18?min (CWT18) duration, or a seated rest control trial. The CWT commenced in hot water (38.4?±?0.6°C) and alternated between hot and cold water (14.6?±?0.3°C) every minute with a 5-s changeover. The cycling protocol was repeated 2?h after completion of exercise bout one. Prior to exercise bout two, core temperature was lower in CWT12 (?0.19?±?0.14°C, mean?±?90% CL) and CWT18 (?0.21?±?0.10°C) than control. Compared with control, CWT6 substantially improved time-trial (1.5?±?2.1%) and sprint performance (3.0?±?3.1%), and CWT12 substantially improved sprint total work (4.3?±?3.4%) and peak power (2.7?±?3.8%) in exercise bout two. All CWT conditions generally improved thermal sensation, whole body fatigue and muscle soreness compared with control, but no differences existed between conditions in heart rate or rating of perceived exertion. In conclusion, CWT duration did not have a dose?Cresponse effect on recovery from high-intensity cycling; however, CWT for up to 12?min assisted recovery of cycling performance. 相似文献
20.
François Péronnet Denis Massicotte Josée -Elise Paquet Guy Brisson Jacques de Champlain 《European journal of applied physiology》1989,58(5):551-555
Summary The purpose of this study was to assess the effects of a 2 h cycle exercise (50%
) on heart rate (HR) and blood pressure (BP), and on plasma epinephrine (E) and norepinephrine (NE) concentrations, during
the recovery period in seven normotensive subjects. Measurements were made at rest in supine (20 min) and standing (10 min)
positions, during isometric exercise (hand-grip, 3 min, 25% maximal voluntary, contraction), in response to a mild psychosocial
challenge (Stroop conflicting color word task) and during a 5-min period of light exercise (42±3%
). Data were compared to measurements taken on another occasion under similar experimental conditions, without a previous
exercise bout (control). The results showed HR to be slightly elevated in all conditions following the exercise bout. However,
diastolic and systolic BP during the recovery period following exercise were not significantly different from the values observed
in the control situation. Plasma NE concentrations in supine position and in response to the various physiological and/or
psychosocial challenges were similar in the control situation and during the recovery period following exercise. On the other
hand plasma E (nmol · l−1) was about 50% lower at rest (0.11±0.03 vs 0.23±0.04) as well as in response to hand-grip (0.21±0.04 vs 0.41±0.20) and the
Stroop-test (0.21±0.05 vs 0.41±0.15) following the exercise bout. This reduction might reflect changes in plasma epinephrine
removal accross the forearm due to changes in blood flow. However, it might also indicate a reduction in the activity of the
adrenal medulla which might have some implications in the use of regular exercise in the control of BP in hyperadrenergic
hypertensive subjects. 相似文献