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1.
Marrin K Drust B Gregson W Morris CJ Chester N Atkinson G 《European journal of applied physiology》2011,111(11):2707-2714
Salivary melatonin concentration is an established marker of human circadian rhythmicity. It is thought that melatonin is
relatively robust to the masking effects of exercise. Nevertheless, the extent and even the direction of exercise-related
change is unclear, possibly due to between-study differences in the time of day exercise is completed. Therefore, we aimed
to compare melatonin responses between morning and afternoon exercise, and explore the relationships between exercise-related
changes in melatonin and heart rate. At 08:00 and 17:00 hours, seven male subjects (mean ± SD age, 27 ± 5 years) completed
30 min of cycling at 70% peak oxygen uptake followed by 30 min of rest. Light intensity was maintained at ~150 lx. Salivary
melatonin (ELISA) and heart rate were measured at baseline, 15 min during exercise, immediately post-exercise and following
30 min recovery. Melatonin was ≈15 pg ml−1 higher in the morning trials compared with the afternoon (P = 0.030). The exercise-related increase in melatonin was more pronounced (P = 0.024) in the morning (11.1 ± 8.7 pg ml−1) than in the afternoon (5.1 ± 5.7 pg ml−1). The slope of the heart rate–melatonin relationship was significantly (P = 0.020) steeper in the morning (0.12 pg ml−1 beats−1 min−1) than in the afternoon (0.03 pg ml−1 beats−1 min−1). In conclusion, we report for the first time that the masking effect of moderate-intensity exercise on melatonin is approximately
twice as high in the morning than the afternoon. The much steeper relationship between heart rate and melatonin changes in
the morning raises the possibility that time of day alters the relationships between exercise-mediated sympathetic nervous
activity and melatonin secretion. 相似文献
2.
Plasma vasopressin,renin activity,and aldosterone responses to maximal exercise in active college females 总被引:1,自引:0,他引:1
Summary The effect of maximal treadmill exercise on plasma concentrations of vasopressin (AVP); renin activity (PRA); and aldosterone
(ALDO) was studied in nine female college basketball players before and after a 5-month basketball season. Pre-season plasma
AVP increased (p<0.05) from a pre-exercise concentration of 3.8±0.5 to 15.8±4.8 pg · ml−1 following exercise. Post-season, the pre-exercise plasma AVP level averaged 1.5±0.5 pg · ml−1 and increased to 16.7±5.9 pg · ml−1 after the exercise test. PRA increased (p<0.05) from a pre-exercise value of 1.6±0.6 to 6.8±1.7 ngAI · ml−1 · hr−1 5 min after the end of exercise during the pre-season test. In the post-season, the pre-exercise PRA was comparable (2.4±0.6
ngAI · ml−1 · hr−1), as was the elevation found after maximal exercise (8.3±1.9 ngAI · ml−1 · hr−1). Pre-season plasma ALDO increased (p<0.05) from 102.9±30.8 pg · ml−1 in the pre-exercise period to 453.8±54.8 pg · ml−1 after the exercise test. In the post-season the values were 108.9±19.4 and 365.9±64.4 pg · ml−1, respectively. Thus, maximal exercise in females produced significant increases in plasma AVP, renin activity, and ALDO that
are comparable to those reported previously for male subjects. Moreover, this response is remarkably reproducible as demonstrated
by the results of the two tests performed 5 months apart. 相似文献
3.
J. P. Kirwan P. M. Clarkson J. E. Graves P. L. Litchfield W. C. Byrnes 《European journal of applied physiology》1986,55(3):330-333
Summary The purpose of this study was to measure serum creatine kinase (CK) activity and serum myoglobin (MG) concentrations in women
after two unilateral isometric knee extension exercises. Forty maximal voluntary contractions (MVC) were held for 10 s, with
either a 5 s (10∶5) or 20 s 10∶20 exercise (349.4±66.1 mU · ml−1) and 6 h and MG values were measured pre, 0, 3, 6, and 18 h post exercise. For CK, the highest post exercise values were
observed at 6 h following the 10∶20 exercise (349.4±66.1 mU · ml−1) and 6 h following the 10∶5 exercise (194.1±18.6 mU · ml−1). For MG, the highest values were found 3 h after the 10∶20 exercise (148.9±61.7 ng · ml−1) and 6 h after the 10∶5 exercise (67.3±10.9 ng · ml−1). Serum CK and MG levels were significantly greater (p<0.01) after the 10∶20 exercise bout. The data demonstrate that CK and MG values for women increase significantly after isometric
exercise. Since greater tension levels were maintained during the 10∶20 exercise it is hypothesized that increased serum CK
and MG values after isometric exercise may be related to the tension generated by the contracting muscle. 相似文献
4.
Michael Morris Kevin L. Lamb John Hayton David Cotterrell John Buckley 《European journal of applied physiology》2010,109(5):983-988
The purpose of this study was to determine for the first time whether
[(V)\dot]\textO 2max {\dot{V}}{\text{O}}_{ 2\hbox{max}} could be predicted accurately and reliably from a treadmill-based perceptually regulated exercise test (PRET) incorporating
a safer and more practical upper limit of RPE 15 (“Hard”) than used in previous investigations. Eighteen volunteers (21.7 ± 2.8 years)
completed three treadmill PRETs (each separated by 48 h) and one maximal graded exercise test. Participants self-regulated
their exercise at RPE levels 9, 11, 13 and 15 in a continuous and incremental fashion. Oxygen uptake
( [(V)\dot]\textO 2 ) \left( {{\dot{V}}{\text{O}}_{ 2} } \right) was recorded continuously during each 3 min bout.
[(V)\dot]\textO2 {\dot{V}}{\text{O}}_{2} values for the RPE range 9–15 were extrapolated to RPE19 and RPE20 using regression analysis to predict individual
[(V)\dot]\textO2max {\dot{V}}{\text{O}}_{2\hbox{max}} scores. The optimal limits of agreement (LoA) between actual (48.0 ± 6.2 ml kg−1 min−1) and predicted scores were −0.6 ± 7.1 and −2.5 ± 9.4 ml.kg−1 min−1 for the RPE20 and RPE19 models, respectively. Reliability analysis for the
[(V)\dot]\textO2max {\dot{V}}{\text{O}}_{2\hbox{max}} predictions yielded LoAs of 1.6 ± 8.5 (RPE20) and 2.7 ± 9.4 (RPE19) ml kg−1 min−1 between trials 2 and 3. These findings demonstrate that (with practice) a novel treadmill-based PRET can yield predictions
of
[(V)\dot]\textO2max {\dot{V}}{\text{O}}_{2\hbox{max}} that are acceptably reliable and valid amongst young, healthy, and active adults. 相似文献
5.
Amorim FT Yamada PM Robergs RA Schneider SM Moseley PL 《European journal of applied physiology》2008,104(6):965-972
Hsp72 concentration has been shown to be higher in the serum (eHsp72) of runners with symptoms of heat illness than in non-ill
runners. Recently, it has been suggested that the rate of heat storage during exercise in the heat may be an important factor
in the development of heat stroke. Therefore, we compared the effect of two rates of heat storage on eHsp72 concentration
during exercise in which subjects reached the same final core temperature. We hypothesized that with a lower rate of heat
storage the increase in eHsp72 would be attenuated compared to a higher rate of heat storage. Nine heat acclimated subjects
performed two exercise trials in a counterbalanced order in the heat (42°C, 30% relative humidity). The trials consisted of
walking on a treadmill (~50% VO 2 peak) dressed in military summer fatigues until rectal temperature reached 38.5°C. A high rate of heat storage (HS, 1.04 ± 0.10 W m−2 min−1, mean ± SE) occurred when subjects walked without cooling. To produce a lower rate of heat storage (LS, 0.54 ± 0.09 W m−2 min−1) subjects walked while wearing a water-perfused cooling vest underneath clothing. eHsp72 increased pre- to post-exercise
(P < 0.05) but there was no difference (P > 0.05) in eHSP between the two rates of heat storage (LS 1.25 ± 0.73 to 2.23 ± 0.70 ng ml−1, HS 1.04 ± 0.57 to 2.02 ± 0.60 ng ml−1). This result suggests that eHsp72 is a function of the core temperature attained rather than the rate of heat storage. 相似文献
6.
Bailey DM Williams C Betts JA Thompson D Hurst TL 《European journal of applied physiology》2011,111(6):925-936
There is no consensus regarding the effects of mixed antioxidant vitamin C and/or vitamin E supplementation on oxidative stress
responses to exercise and restoration of muscle function. Thirty-eight men were randomly assigned to receive either placebo
group (n = 18) or mixed antioxidant (primarily vitamin C & E) supplements (n = 20) in a double-blind manner. After 6 weeks, participants performed 90 min of intermittent shuttle-running. Peak isometric
torque of the knee flexors/extensors and range of motion at this joint were determined before and after exercise, with recovery
of these variables tracked for up to 168 h post-exercise. Antioxidant supplementation elevated pre-exercise plasma vitamin
C (93 ± 8 μmol l−1) and vitamin E (11 ± 3 μmol l−1) concentrations relative to baseline (P < 0.001) and the placebo group (P ≤ 0.02). Exercise reduced peak isometric torque (i.e. 9–19% relative to baseline; P ≤ 0.001), which persisted for the first 48 h of recovery with no difference between treatment groups. In contrast, changes
in the urine concentration of F2-isoprostanes responded differently to each treatment (P = 0.04), with a tendency for higher concentrations after 48 h of recovery in the supplemented group (6.2 ± 6.1 vs. 3.7 ± 3.4 ng ml−1). Vitamin C & E supplementation also affected serum cortisol concentrations, with an attenuated increase from baseline to
the peak values reached after 1 h of recovery compared with the placebo group (P = 0.02) and serum interleukin-6 concentrations were higher after 1 h of recovery in the antioxidant group (11.3 ± 3.4 pg ml−1) than the placebo group (6.2 ± 3.8 pg ml−1; P = 0.05). Combined vitamin C & E supplementation neither reduced markers of oxidative stress or inflammation nor did it facilitate
recovery of muscle function after exercise-induced muscle damage. 相似文献
7.
Plasma norepinephrine and heart rate dynamics during recovery from submaximal exercise in man 总被引:2,自引:0,他引:2
Renza Perini Claudio Orizio Alessandro Comandè Maurizio Castellano Marina Beschi Arsenio Veicsteinas 《European journal of applied physiology》1989,58(8):879-883
Summary The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expression of the sympathetic
nervous activity (SNA), was studied in six sedentary young men during recovery from three periods of cycle ergometer exercise
at 21%±2.8%, 43%±2.1% and 65%±2.3% of
respectively (mean±SE). The HR decreased mono-exponentially withτ values of 13.6±1.6 s, 32.7±5.6 s and 55.8±8.1s respectively in the three periods of exercise. At the low exercise level no
change in [NE] was found. At medium and high exercise intensity: (a) [NE] increased significantly at the 5th min of exercise
(Δ[NE]=207.7±22.5 pg·ml−1 and 521.3±58.3 pg·ml−1 respectively); (b) after a time lag of 1 min [NE] decreased exponentially (τ=87 s and 101 s respectively); (c) in the 1st min HR decreased about 35 beats · min−1; (d) from the 2nd to 5th min of recovery HR and [NE] were linearly related (100 pg·ml−1
Δ[NE]5 beats ·min−1). In the 1st min of recovery, independent of the exercise intensity, the adjustment of HR appears to have been due mainly
to the prompt restoration of vagal tone. The further decrease in HR toward the resting value could then be attributed to the
return of SNA to the pre-exercise level. 相似文献
8.
Induction and decay of short-term heat acclimation 总被引:1,自引:0,他引:1
Andrew T. Garrett Niels G. Goosens Nancy G. Rehrer Mark J. Patterson James D. Cotter 《European journal of applied physiology》2009,107(6):659-670
The purpose of this work was to investigate adaptation and decay from short-term (5-day) heat acclimation (STHA). Ten moderately
trained males (mean ± SD age 28 ± 7 years; body mass 74.6 ± 4.4 kg;
[(V)\dot]\textO 2\textpeak \dot{V}_{{{\text{O}}_{ 2{\text{peak}}} }} 4.26 ± 0.37 l min−1) underwent heat acclimation (Acc) for 90-min on 5-days consecutively (T
a = 39.5°C, 60% RH), under controlled hyperthermia (rectal temperature 38.5°C). Participants completed a heat stress test (HST)
1 week before acclimation (Acc), then on the 2nd and 8th day (1 week) following Acc (T
a = 35°C, 60% RH). Seven participants completed HSTs 2 and 3 weeks after Acc. HST consisted of 90-min cycling at 40% peak power
output before an incremental performance test. Rectal temperature at rest (37.1 ± 0.4°C) was not lowered by Acc (95% CI −0.3
to 0.2°C), after 90-min exercise (38.6 ± 0.5°C) it reduced 0.3°C (−0.5 to −0.1°C) and remained at this level 1 week later
(−0.5 to −0.1°C), but not two (0.1°C −0.4 to 0.5°C; n = 7) or 3 weeks. Similarly, heart rate after 90-min exercise (146 ± 21 b min−1) was reduced (−13: −6 to −20 b min−1) and remained at this level after 1 week (−13: −6 to −20 b min−1) but not two (−9: 6 to −23 b min−1; n = 7) or 3 weeks. Performance (746 s) increased 106 s: 59 to 152 s after Acc and remained higher after one (76 s: 31 to 122)
but not two (15 s: −88 to 142 s; n = 7) or 3 weeks. Therefore, STHA (5-day) induced adaptations permitting increased heat loss and this persisted 1 week but
not 2 weeks following Acc. 相似文献
9.
Ye Tian Jinlei Nie Tom K. Tong Julien S. Baker Non Eleri Thomas Qingde Shi 《European journal of applied physiology》2010,110(5):971-976
It is well documented that intense exercise precipitates oxidative stress in adults. However, there is lack of related studies
concerning oxidant and antioxidant status during early and late recovery periods in adolescent athletes, following endurance
exercise in particular. This study investigated aspects of the serum oxidant and antioxidant status of 12 male adolescent
(16.2 ± 0.6 years) trained runners during early and late recovery periods after an all-out 21-km run. Venous blood samples
were taken immediately before, 2 and 4 h following (early recovery period), and 24 h following (late recovery period) the
21-km run. Samples were analyzed for serum concentrations of thiobarbituric acid-reactive substances (TBARS), uric acid (UA),
reduced glutathione (GSH), and enzymatic activity of xanthine oxidase (XO), superoxide dismutase (SOD), and catalase (CAT).
During the early recovery period, there were increases in the 4-h GSH (194.8 ± 10.4 vs. 211.8 ± 11.4 mg l−1, P < 0.05), 2- and 4-h UA (307.8 ± 68.6 vs. 327.4 ± 63.8; 330.2 ± 65.1 μmol l−1, P < 0.05), and 2-h CAT (2.05 ± 0.44 vs. 3.07 ± 0.51 U ml−1, P < 0.05), and decreases in the 2-h XO (11.1 ± 1.5 vs. 10.3 ± 1.2 U l−1, P < 0.05) compared to the corresponding pre-exercise level, respectively. No change was observed in SOD (P > 0.05). At the late recovery period, there was an increase in CAT (2.80 ± 0.49 U ml−1, P < 0.05) and TBARS (2.99 ± 0.83 vs. 4.40 ± 1.38 nmol ml−1, P < 0.05). These data indicate that although the antioxidant capacity of adolescent runners is augmented during the early recovery
period following the 21-km run, they were not completely protected from oxidative stress during the later recovery period. 相似文献
10.
Maren S. Fragala William J. Kraemer Jeff S. Volek Carl M. Maresh Michael J. Puglisi Jakob L. Vingren Jen-Yu Ho Disa L. Hatfield Barry A. Spiering Cassandra E. Forsythe Gwendolyn A. Thomas Erin E. Quann Jeffrey M. Anderson Robert L. Hesslink Jr 《European journal of applied physiology》2009,105(5):665-672
The influence of a proprietary blend of modified cellulose and cetylated fatty acids (Trisynex™, Imagenetix, Inc., San Diego,
CA 92127, USA) on adipocytokine and regional body composition responses to a weight loss program was examined. Twenty-two
women (Supplement group (S) (n = 11): age = 36.8 ± 7.2 years; weight = 87.1 ± 6.2 kg; % body fat = 43.4 ± 4.1; Placebo group (P) (n = 11): age = 38.3 ± 6.8 years; weight = 86.9 ± 4.7 kg; % body fat = 44.3 ± 2.0) completed an 8-week placebo-controlled, double-blind
study consisting of a caloric restricted diet and cardiovascular exercise. Body composition and serum insulin, leptin, and
adiponectin were assessed at pre-, mid-, and post-intervention. From pre- to post-intervention, significant decreases (P < 0.05) were observed for body weight (S: 87.1 ± 6.2–77.9 ± 5.1 kg; P: 86.9 ± 4.7–82.7 ± 3.8 kg) (P < 0.05 S vs. P), % body fat (S: 43.4 ± 4.1–36.1 ± 3.6; P: 44.3 ± 2.0–40.6 ± 1.2) (P < 0.05 S vs. P), leptin (S: 28.3 ± 3.5–16.2 ± 2.6 ng ml−1; P: 29.4 ± 3.2–19.9 ± 1.1 ng ml−1) (P < 0.05 S vs. P), and insulin (S: 7.3 ± 0.8–5.1 ± 0.2 mU l−1; P: 7.7 ± 0.9–5.1 ± 0.3 mU l−1). Serum adiponectin increased (P < 0.05) (S: 12.2 ± 2.4–26.3 ± 3.0 μg ml−1: 12.6 ± 2.0–21.8 ± 3.1 μg ml−1) (P < 0.05 for S vs. P). Supplementation with a proprietary blend of modified cellulose and cetylated fatty acids during an 8-week
weight loss program exhibited favorable effects on adipocytokines and regional body composition. 相似文献
11.
Lai N Tolentino-Silva F Nasca MM Silva MA Gladden LB Cabrera ME 《European journal of applied physiology》2012,112(3):973-982
The effect of exercise intensity on the on- and off-transient kinetics of oxygen uptake (VO2) was investigated in African American (AA) and Caucasian (C) women. African American (n = 7) and Caucasian (n = 6) women of similar age, body mass index and weight, performed an incremental test and bouts of square-wave exercise at
moderate, heavy and very heavy intensities on a cycle ergometer. Gas exchange threshold (LTGE) was lower in AA (13.6 ± 2.3 mL kg−1 min−1) than C (18.6 ± 5.6 mL kg−1 min−1). The dynamic exercise and recovery VO2 responses were characterized by mathematical models. There were no significant differences in (1) peak oxygen uptake (VO2peak) between AA (28.5 ± 5 mL kg−1 min−1) and C (31.1 ± 6.6 mL kg−1 min−1) and (2) VO2 kinetics at any exercise intensity. At moderate exercise, the on- and off- VO2 kinetics was described by a monoexponential function with similar time constants τ
1,on (39.4 ± 12.5; 38.8 ± 15 s) and τ
1,off (52.7 ± 10.1; 40.7 ± 4.4 s) for AA and C, respectively. At heavy and very heavy exercise, the VO2 kinetics was described by a double-exponential function. The parameter values for heavy and very heavy exercise in the AA
group were, respectively: τ
1,on (47.0 ± 10.8; 44.3 ± 10 s), τ
2,on (289 ± 63; 219 ± 90 s), τ
1,off (45.9 ± 6.2; 50.7 ± 10 s), τ
2,off (259 ± 120; 243 ± 93 s) while in the C group were, respectively: τ
1,on (41 ± 12; 43.2 ± 15 s); τ
2, on (277 ± 81; 215 ± 36 s), τ
1,off (40.2 ± 3.4; 42.3 ± 7.2 s), τ
2,off (215 ± 133; 228 ± 64 s). The on- and off-transients were symmetrical with respect to model order and dependent on exercise
intensity regardless of race. Despite similar VO2 kinetics, LTGE and gain of the VO2 on-kinetics at moderate intensity were lower in AA than C. However, generalization to the African American and Caucasian
populations is constrained by the small subject numbers. 相似文献
12.
The recent surge in childhood obesity has renewed interest in studying exercise as a therapeutic means of metabolizing fat.
However, carbohydrate (CHO) intake attenuates whole body fat oxidation during exercise in healthy children and may suppress
fat metabolism in obese youth. To determine the impact of CHO intake on substrate utilization during submaximal exercise in
obese boys, seven obese boys (mean age: 11.4 ± 1.0 year; % body fat: 35.8 ± 3.9%) performed 60 min of exercise at an intensity
that approximated maximal fat oxidation. A CHO drink (CARB) or a placebo drink (CONT) was consumed in a double-blinded, counterbalanced
manner. Rates of total fat, total CHO, and exogenous CHO (CHOexo) oxidation were calculated for the last 20 min of exercise. During CONT, fat oxidation rate was 3.9 ± 2.4 mg × kg fat-free
mass (FFM)−1 × min−1, representing 43.1 ± 22.9% of total energy expenditure (EE). During CARB, fat oxidation was lowered (p = 0.02) to 1.7 ± 0.6 mg × kg FFM−1 × min−1, contributing to 19.8 ± 4.9% EE. Total CHO oxidation rate was 17.2 ± 3.1 mg × kg FFM−1 × min−1 and 13.2 ± 6.1 mg × kg FFM−1 × min−1 during CARB and CONT, respectively (p = 0.06). In CARB, CHOexo oxidation contributed to 23.3 ± 4.2% of total EE. CHO intake markedly suppresses fat oxidation during exercise in obese boys. 相似文献
13.
We have previously demonstrated that provision of a cold fluid (4°C) during exercise in the heat increases fluid intake and
improves exercise capacity when compared to a control fluid (19°C). The present study investigated whether these positive
effects could simply be replicated with a cooling agent, menthol. Nine healthy, non-acclimatised males (25 ± 7 years; [(V)\dot] \dot{V} O2max: 54 ± 5 ml kg−1 min−1) cycled to exhaustion at 65% of their peak aerobic power output at 34°C, swilling 25 ml of either an l(−)-menthol (0.01%) or orange-flavoured placebo solution every 10 min, whilst water was available ad libitum; all fluids were
kept at 19°C. Eight out of nine subjects cycled for longer whilst swilling with menthol and this resulted in a 9 ± 12% improvement
in endurance capacity. Rectal temperatures rose by 1.7°C during exercise with the same time course in both conditions, whilst
skin temperature remained largely unchanged. Swilling with menthol resulted in hyperventilation by 8 ± 10 L min−1 and reduced central (cardiopulmonary) ratings of perceived exertion by 15 ± 14%. No differences between trials were observed
for heart rate, oxygen uptake or carbon dioxide production, blood concentrations of glucose or lactate, sweat rate or volume
of water ingested. We conclude that a change in the sensation of oropharyngeal temperature during exercise in the heat significantly
affects endurance capacity, ventilation and the (central) sense of effort. 相似文献
14.
Ribeiro LF Gonçalves CG Kater DP Lima MC Gobatto CA 《European journal of applied physiology》2009,105(2):159-165
This study analyzed the influence of recovery phase manipulation after hyperlactemia induction on the lactate minimum intensity
during treadmill running. Twelve male runners (24.6 ± 6.3 years; 172 ± 8.0 cm and 62.6 ± 6.1 kg) performed three lactate minimum
tests involving passive (LMTP) and active recoveries at 30%vVO2max (LMTA30) and 50%vVO2max (LMTA50) in the 8-min period following initial sprints. During subsequent graded exercise, lactate minimum speed and VO2 in LMTA50 (12.8 ± 1.5 km h−1 and 40.3 ± 5.1 ml kg−1 min−1) were significantly lower (P < 0.05) than those in LMTA30 (13.3 ± 1.6 km h−1 and 42.9 ± 5.3 ml kg−1 min−1) and LMTP (13.8 ± 1.6 km h−1 and 43.6 ± 6.1 ml kg−1 min−1). In addition, lactate minimum speed in LMTA30 was significantly lower (P < 0.05) than that in LMTP. These results suggest that lactate minimum intensity is lowered by active recovery after hyperlactemia induction in an intensity-dependent
manner compared to passive recovery. 相似文献
15.
Clarke ND Maclaren DP Reilly T Drust B 《European journal of applied physiology》2011,111(7):1447-1455
Ingestion of carbohydrate and reducing core body temperature pre-exercise, either separately or combined, may have ergogenic
effects during prolonged intermittent exercise in hot conditions. The aim of this investigation was to examine the effect
of carbohydrate ingestion and pre-cooling on the physiological responses to soccer-specific intermittent exercise and the
impact on subsequent high-intensity exercise performance in the heat. Twelve male soccer players performed a soccer-specific
intermittent protocol for 90 min in the heat (30.5°C and 42.2% r.h.) on four occasions. On two occasions, the participants underwent a pre-cooling manoeuvre. During these sessions either a
carbohydrate–electrolyte solution (CHOc) or a placebo was consumed at (PLAc). During the remaining sessions either the carbohydrate–electrolyte
solution (CHO) or placebo (PLA) was consumed. At 15-min intervals throughout the protocol participants performed a mental
concentration test. Following the soccer-specific protocol participants performed a self-chosen pace test and a test of high-intensity
exercise capacity. The period of pre-cooling significantly reduced core temperature, muscle temperature and thermal sensation
(P < 0.05). Self-chosen pace was greater with CHOc (12.5 ± 0.5 km h−1) compared with CHO (11.3 ± 0.4 km h−1), PLA (11.3 ± 0.4 km h−1) and PLAc (11.6 ± 0.5 km h−1) (P < 0.05). High-intensity exercise capacity was improved with CHOc and CHO when compared with PLA (CHOc; 79.8 ± 7 s, CHO; 72.1 ± 5 s,
PLAc; 70.1 ± 8 s, PLA; 57.1 ± 5 s; P < 0.05). Mental concentration during the protocol was also enhanced during CHOc compared with PLA (P < 0.05). These results suggest pre-cooling in conjunction with the ingestion of carbohydrate during exercise enhances exercise
capacity and helps maintain mental performance during intermittent exercise in hot conditions. 相似文献
16.
Carole A. Williams J. G. Mudd Alexander R. Lind 《European journal of applied physiology》1985,54(2):156-162
Summary Experiments were performed to assess the possible neurally mediated constriction in active skeletal muscle during isometric
hand-grip contractions. Forearm blood flow was measured by venous occlusion plethysmography on 5 volunteers who exerted a
series of repeated contractions of 4 s duration every 12 s at 60% of their maximum strength of fatigue. The blood flows increased
initially, but then remained constant at 20–24 ml·min−1·100 ml−1 throughout the exercise even though mean arterial blood pressure reached 21–23 kPa (160–170 mm Hg). When the same exercise
was performed after arterial infusion of phentolamine, forearm blood flow increased steadily to near maximal levels of 38.7±1.4
ml·min−1·100 ml−1.
Venous catecholamines, principally norepinephrine, increased throughout exercise, reaching peak values of 983±258 pg·ml−1 at fatigue. Of the vasoactive substances measured, the concentration of K+ and osmolarity in venous plasma also increased initially and reached a steady-state during the exercise but ATP increased
steadily throughout the exercise. These data indicate a continually increasing α-adrenergic constriction to the vascular beds
in active muscles in the human forearm during isometric exercise, that is only partially counteracted by vasoactive metabolites. 相似文献
17.
Legaz-Arrese A George K Carranza-García LE Munguía-Izquierdo D Moros-García T Serrano-Ostáriz E 《European journal of applied physiology》2011,111(12):2961-2967
We sought to determine the influence of exercise intensity on the release of cardiac troponin I (cTnI) and N-terminal pro-brain
natriuretic peptide (NT-proBNP) in amateur marathon runners. Fourteen runners completed three exercise trials of the same
duration but at exercise intensities corresponding to: (a) a competitive marathon [mean ± SD: heart rate 159 ± 7 beat min−1, finish time 202 ± 14 min]; (b) 95% of individual anaerobic threshold [heart rate 144 ± 6 beat min−1] and; (c) 85% of individual anaerobic threshold [heart rate 129 ± 5 beat min−1]. cTnI and NT-proBNP were assayed from blood samples collected before, 30 min and 3 h post-exercise for each trial. cTnI
and NT-proBNP were not different at baseline before each trial. After exercise at 85% of individual anaerobic threshold cTnI
was not significantly elevated. Conversely, cTnI was elevated after exercise at 95% of individual anaerobic threshold (0.016 μg L−1) and to an even greater extent after exercise at competition intensity (0.054 μg L−1). Peak post-exercise values of NT-proBNP were elevated to a similar extent after all exercise trials (P < 0.05). The upper reference limit for cTnI (0.04 μg L−1) was exceeded in six subjects at competition intensity. No data for NT-proBNP surpassed its upper reference limit. Peak post-exercise
values for cTnI and NT-proBNP were correlated with their respective baseline values. These data suggest exercise intensity
influences the release of cTnI, but not NT-proBNP, and that competitive marathon running intensity is required for cTnI to
be elevated over its upper reference limit. 相似文献
18.
Gary J. Hodges Lisa Sharp Claire Stephenson Ashish Y. Patwala Keith P. George David F. Goldspink N. Tim Cable 《European journal of applied physiology》2010,108(6):1259-1267
Skin blood flow (SkBF) and endothelial-dependent vasodilatation decline with ageing and can be reversed with exercise training.
We tested whether 48 weeks of training could improve SkBF and endothelial function in post-menopausal females; 20 post-menopausal
subjects completed the study. SkBF was measured by laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was
calculated as LDF/blood pressure. Resting CVC was measured at 32°C and peak CVC at 42°C. Cutaneous endothelial-dependent and
-independent vasodilatations were determined by the iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP), respectively.
All assessments described were performed at entry (week 0), and after 6, 12, 24, 36, and 48 weeks of training. Resting CVC
measures did not change (P > 0.05) throughout the study. Peak CVC increased (P < 0.05) after 24 weeks (7.2 ± 1.2 vs. 11.6 ± 1.4 AU mmHg−1) and at the 36- and 48-week assessments (13.0 ± 1.7 and 14.9 ± 2.1 AU mmHg−1, respectively). Responses to ACh also increased (P < 0.05) at the 24-week assessment (5.1 ± 2.1 vs. 8.55 ± 2.3 AU mmHg−1) and increased further at the 36 and 48-week assessments (11.6 ± 3.7 and 13.2 ± 3.9 AU mmHg−1, respectively). Cutaneous responses to SNP increased (P < 0.05) after 36 weeks (8.7 ± 2.1 vs. 13.02 ± 2.23 AU mmHg−1 at 36 weeks). VO2max increased after 12 weeks (23.5 ± 0.7 vs. 25.4 ± 0.9 ml kg−1 min−1) and improved (P < 0.05) further throughout the study (31.6 ± 1.8 ml kg−1 min−1 at week 48). Aerobic exercise produces positive adaptations in the cutaneous vasodilator function to local heating as well
as in cutaneous endothelial and endothelial-independent vasodilator mechanisms. Aerobic capacity was also significantly improved.
These adaptations were further enhanced with progressive increases in exercise intensity. 相似文献
19.
Rowland T Unnithan V Roche D Garrard M Holloway K Marwood S 《European journal of applied physiology》2011,111(9):1991-1997
A recent report indicated that variations in myocardial functional (systolic and diastolic) responses to exercise do not contribute
to inter-individual differences in aerobic fitness (peak VO2) among young males. This study was designed to investigate the same question among adolescent females. Thirteen highly fit
adolescent football (soccer) players (peak VO2 43.5 ± 3.4 ml kg−1 min−1) and nine untrained girls (peak VO2 36.0 ± 5.1 ml kg−1 min−1) matched for age underwent a progressive cycle exercise test to exhaustion. Cardiac variables were measured by standard echocardiographic
techniques. Maximal stroke index was greater in the high-fit group (50 ± 5 vs. 41 ± 4 ml m−2), but no significant group differences were observed in maximal heart rate or arterial venous oxygen difference. Increases
in markers of both systolic (ejection rate, tissue Doppler S′) and diastolic (tissue Doppler E′, mitral E velocity) myocardial functions at rest and during the acute bout of exercise were similar in the two groups. This study suggests
that among healthy adolescent females, like young males, myocardial systolic and diastolic functional capacities do not contribute
to inter-individual variability in physiologic aerobic fitness. 相似文献
20.
The purpose of this study was to assess cardiac function and arteriovenous oxygen difference (a-vO2 difference) at rest and during exercise in young, normal-weight (n = 20), and obese (n = 12) men and women who were matched for age and fitness level. Participants were assessed for body composition, peak oxygen
consumption (VO2peak), and cardiac variables (thoracic bioimpedance)—cardiac index (CI), cardiac output (Q), stroke volume (SV), heart rate (HR),
and ejection fraction (EF)—at rest and during cycling exercise at 65% of VO2peak. Differences between groups were assessed with multivariate ANOVA and mixed-model ANOVA with repeated measures controlling
for sex. Absolute VO2peak and VO2peak relative to fat-free mass (FFM) were similar between normal-weight and obese groups (Mean ± SEE 2.7 ± 0.2 vs. 3.3 ± 0.3 l min−1, p = 0.084 and 52.4 ± 1.5 vs. 50.9 ± 2.3 ml kg FFM−1 min−1, p = 0.583, respectively). In the obese group, resting Q and SV were higher (6.7 ± 0.4 vs. 4.9 ± 0.1 l min−1, p < 0.001 and 86.8 ± 4.3 vs. 65.8 ± 1.9 ml min−1, p < 0.001, respectively) and EF lower (56.4 ± 2.2 vs. 65.5 ± 2.2%, p = 0.003, respectively) when compared with the normal-weight group. During submaximal exercise, the obese group demonstrated
higher mean CI (8.8 ± 0.3 vs. 7.7 ± 0.2 l min−1 m−2, p = 0.007, respectively), Q (19.2 ± 0.9 vs. 13.1 ± 0.3 l min−1, p < 0.001, respectively), and SV (123.0 ± 5.6 vs. 88.9 ± 4.1 ml min−1, p < 0.001, respectively) and a lower a-vO2 difference (10.4 ± 1.0 vs. 14.0 ± 0.7 ml l00 ml−1, p = 0.002, respectively) compared with controls. Our study suggests that the ability to extract oxygen during exercise may
be impaired in obese individuals. 相似文献