共查询到20条相似文献,搜索用时 15 毫秒
1.
Michael J. Price Ian G. Campbell 《European journal of applied physiology and occupational physiology》1997,76(6):552-560
The thermoregulatory responses of ten paraplegic (PA; T3/4-L4) and nine able-bodied (AB) upper body trained athletes were
examined at rest and during prolonged arm-cranking exercise and passive recovery. Exercise was performed for 90 min at 80%
peak heart rate, and at 21.5 (1.7)°C and 47.0 (7.8)% relative humidity on a Monark cycle ergometer (Ergomedic 814E) adapted
for arm exercise. Mean peak oxygen uptake values for the PA and AB athlete groups were 2.12 (0.41) min−1 and 3.19 (0.38) l · min−1, respectively (P<0.05). At rest, there was no difference in aural temperature between groups [36.2 (0.4)°C for both groups]. However, upper
body skin temperatures for the PA athletes were approximately 1.0 °C warmer than for the AB athletes, whereas lower body skin
temperatures were cooler than those for the AB athletes (1.3 °C and 2.7 °C for the thigh and calf, respectively). Upper and
lower body skin temperatures for the AB athletes were similar. During exercise, blood lactate peaked after 15 min of exercise
for both groups [3.33 (1.26) mmol · l−1 and 4.30 (1.03) mmol · l−1 for the PA and AB athletes, respectively, P<0.05] and decreased throughout the remainder of the exercise period. Aural temperature increased by 0.7 (0.5)°C and 0.6 (0.4)°C
for the AB and PA athletes, respectively. Calf skin temperature for the PA athletes increased during exercise by 1.4 (2.8)°C
(P<0.05), whereas a decrease of 0.8 (2.0)°C (P<0.05) was observed for the AB athletes. During the first 20 min of recovery from exercise, the calf skin temperature of the
AB athletes decreased further [−2.6 (1.3)°C; P<0.05]. Weight losses and changes in plasma volume were similar for both groups [0.7 (0.5) kg and 0.7 (0.4) kg; 5.4 (4.9)%
and 9.7 (6.2)% for the PA and AB athletes, respectively]. In conclusion, the results of this study suggest that the PA athletes
exhibit different thermoregulatory responses at rest and during exercise and passive recovery to those of upper body trained
AB athletes. Despite this, during 90 min of arm-crank exercise in a cool environment, the PA athletes appeared to be at no
greater thermal risk than the AB athletes.
Accepted: 7 May 1997 相似文献
2.
Carmel M. McEniery David G. Jenkins Christopher Barnett 《European journal of applied physiology and occupational physiology》1997,75(5):462-466
The present study investigated the relationship between plasma potassium ion concentration ([K+]) and skeletal muscle torque during three different 15-min recovery periods after fatigue induced by four 30-s sprints. Four
males and one female completed the multiple sprint exercise on three separate days; recovery was passive, i.e. no cycling
exercise (PRec), active cycling at 30% peak oxygen consumption O2peak (30% Rec) and active cycling at 60% O2peak (60% Rec). Plasma [K+] was measured from blood sampled from an antecubital vein of subjects at rest and at 0, 3, 5, 10 and 15 min into each recovery.
Isokinetic leg strength was measured at rest and at 1, 6, 11 and 16 min during each recovery. Following the exhaustive sprints,
[K+] increased significantly from an average mean (SEM) resting value of 3.81 (0.07) mmol · l−1 to 4.48 (0.19) mmol · l−1 (P < 0.01). In all recovery conditions, plasma [K+] returned to resting levels within 3 min following the fourth sprint. However, in the two active recovery conditions plasma
[K+] increased over the remainder of the recovery periods to 4.36 (0.12) mmol · l−1 in the 30% Rec condition and 4.62 (0.12) mmol · l−1 in the 60% Rec condition, the latter being significantly higher than the former (P < 0.01). The maximum torque measured following the sprints decreased significantly, on average, to 61.1 (8.36)% of peak levels
(P < 0.01). After 15 min of recovery, maximum torque was highest in the 30% Rec condition at 92.13 (3.06)% of peak levels (P < 0.01), compared to 85.23 (3.64)% and 85.71 (0.82)% for the PRec and 60% Rec conditions, respectively. In contrast to the
significant differences in plasma [K+] across all three recovery conditions, muscle torque recovery was significantly different in only the 30% Rec condition.
In summary, recovery of peak levels of muscle torque following fatiguing exercise does not appear to follow changes in plasma
[K+].
Accepted: 18 October 1996 相似文献
3.
David Ben-Sira Michael Sagiv 《European journal of applied physiology and occupational physiology》1997,75(6):549-553
The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied
during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years]
volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed
with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating
ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction
effect with stroke volume (P < 0.05) was characterized by a decrease in the men and an increase of stroke volume in the women. Cardiac output rose significantly
(P < 0.05) up to 14.5 (SD 6) l · min−1) for the men and 12.1 (SD 4) l · min−1 for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) l · min−1, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P < 0.05). During exercise these differences showed an interaction effect (P < 0.05). These results would indicate that normal men and women respond to sudden strenuous exercise by reducing their left
ventricular systolic function, with a significantly greater decrease in women (P < 0.05). The gender differences in the haemodynamic responses during the present study, may, as suggested by others, be attributable
to differences in energy metabolism. In addition, changes in Doppler parameters of aortic flow, haemodynamics and blood pressure
responses during sudden strenuous exercise differed markedly from those seen before with endurance exercise.
Accepted: 8 January 1997 相似文献
4.
H. J. Bogaard H. H. Woltjer B. M. Dekker A. R. J. van Keimpema P. E. Postmus P. M. J. M. de Vries 《European journal of applied physiology and occupational physiology》1997,75(5):435-442
Whereas with advancing age, peak heart rate (HR) and cardiac index (CI) are clearly reduced, peak stroke index (SI) may decrease,
remain constant or even increase. The aim of this study was to describe the patterns of HR, SI, CI, arteriovenous difference
in oxygen concentration (C
a-vO2), mean arterial pressure (MAP), systemic vascular resistance index (SVRI), stroke work index (SWI) and mean systolic ejection
rate index (MSERI) in two age groups (A: 20–30 years, n = 20; B: 50–60 years n = 20. After determination of pulmonary function, an incremental bicycle exercise test was performed, with standard gas-exchange
measurements and SI assessment using electrical impedance cardiography. The following age-related changes were found: similar
submaximal HR response to exercise in both groups and a higher peak HR in A than in B[185 (SD 9) vs 167 (SD 14) beats · min−1, P < 0.0005]; increase in SI with exercise up to 60–90 W and subsequent stabilization in both groups. As SI decreased towards
the end of exercise in B, a higher peak SI was found in A [57.5 (SD 14.0) vs 43.6 (SD 7.7) ml · m−2, P < 0.0005]; similar submaximal CI response to exercise, higher peak CI in A [10.6 (SD 2.5) vs 7.2 (SD 1.3) l · min−1 · m−2, P < 0.0005]; no differences in C
a-vO2 during exercise; higher MAP at all levels of exercise in B; higher SVRI at all levels of exercise in B; lower SWI in B after
recovery; higher MSERI at all levels of exercise in A. The decrease in SI with advancing age would seem to be related to a
decrease in myocardial contractility, which can no longer be compensated for by an increase in preload (as during submaximal
exercise). Increases in systemic blood pressure may also compromise ventricular function but would seem to be of minor importance.
Accepted: 24 September 1996 相似文献
5.
K. S. M. T. Mudambo G. P. Leese M. J. Rennie 《European journal of applied physiology and occupational physiology》1997,75(2):109-114
The effects of exercise on gastric emptying remain controversial, with some workers reporting that heavy exercise inhibits
it to varying degrees whereas others report no effects up to an intensity of 70% maximal oxygen consumption (O2max). The state of hydration of the subjects and the environmental conditions may influence the rate of gastric emptying during
exercise. To understand further the effects of a 3-h, 16-km walk/run carrying 30 kg of equipment under field conditions at
39°C, we estimated gastric emptying using a [13C]acetate breath test method. Breath samples were collected at intervals after giving 150 mg of [13C]acetate. The effects of giving a standard volume (530 ml) of water or dextrose (7.5 g · 100 ml−1) with electrolytes or fructose/corn solids (7.5 g · 100 ml−1) at rest before exercise were compared with those of exercise and of recovery after exercise with or without extra fluids
(400 ml each 20 min). At rest, after a standard 530-ml load, gastric emptying times [mean (SE)] were: 37 (2) min (water),
46 (3) min (dextrose/electrolytes) and 47 (5) min (fructose/corn solids) and were significantly slower (P < 0.05) than those occurring after extra fluid ingestion, i.e. 32 (3), 39 (2) and 41 (3) min respectively. After a standard
530-ml load, emptying times during exercise were almost identical to those at rest but, during exercise, extra fluid speeded
up gastric emptying more than at rest to 24 (2), 26 (1) and 27 (5) min (P < 0.05) respectively. During resting recovery without extra fluids, gastric emptying was significantly slowed to 60 (2),
71 (5) and 78 (3) min, respectively. Although emptying times during recovery from exercise with extra fluid were faster [49
(6), 55 (2) and 58 (4) min, respectively], they were still slower than before exercise. The results suggest that: (1) extra
fluid increases gastric emptying more during exercise than at rest, and (2) gastric emptying during resting recovery from
exercise is slower than at rest before exercise whether or not fluid has previously been taken.
Accepted: 17 June 1996 相似文献
6.
K. H?kkinen A. Pakarinen R. U. Newton W. J. Kraemer 《European journal of applied physiology and occupational physiology》1998,77(4):312-319
Acute hormone responses of growth hormone (GH), total and free testosterone (TT and FT) and cortisol (C) to heavy resistance
isometric exercise were examined in ten young men [YM 26.5 (SD 4.8) years] and ten old men [OM 70.0 (SD 3.7) years]. Loading
conditions of the same relative intensity were created for the lower and upper extremity actions separately as well as for
both of them together – lower extremity exercise (LE; knee extension), upper extremity exercise (UE; bench press extension),
and lower and upper extremity exercise (LUE) performed simultaneously in a seated position. Single voluntary maximal isometric
actions lasting for 5 s were performed repeatedly for ten repetitions (with a recovery of 5 s) for a total of four sets. The
recovery time between the sets was 1 min. Each exercise led to large acute decreases in maximal isometric force in both YM
(P < 0.001) and OM (P < 0.001) ranging from 41% to 26% with no significant differences between the groups. Serum GH concentrations increased in
both YM (P < 0.05–0.01) and OM (P < 0.05) but the postexercise value in YM during LE was greater (P < 0.05) than for OM. The TT increased (P < 0.01–0.001) in YM in all three exercises, while in OM the increase occurred only during LE (P < 0.01). The exercises led to increases in FT in YM (P < 0.05 for LE and LUE), while in OM the increase occurred only during LUE (P < 0.05). The pre and postexercise FT were greater in YM (P < 0.001) than in OM. No significant changes occurred in C either in YM or in OM. The blood lactate concentrations increased
during the exercises in both YM (P < 0.001) and OM (P < 0.05–0.001) but the postexercise values during LE and LUE in YM were greater (P < 0.05) than in OM. The present data would indicate that the responses of GH, TT and FT to heavy resistance isometric exercise
are lowered with increasing age. The reduced acute hormone response together with the lowered basal values in FT in the older
men compared to the young men may indicate decreased anabolic effects on muscles and may explain in part the loss of muscle
mass and strength associated with aging.
Accepted: 18 August 1997 相似文献
7.
B. Mercier P. Granier J. Mercier L. Foucat G. Bielicki J. Pradere J. P. Renou C. Prefaut 《European journal of applied physiology and occupational physiology》1998,78(1):20-27
We investigated whether localized 1H nuclear magnetic resonance spectroscopy (NMRS) using stimulated echoes (STEAM) with a long mixing time (t
m) allowed the suppression of the fat signal and detection of lactate in skeletal muscle. The 1H NMRS sequence was first validated in three isolated and perfused rabbit biceps brachii muscles. Spectra were obtained on a wide-bore spectrometer using a dual-tuned probe (1H and 31P). Death was simulated by ceasing the muscle perfusion, which allowed post-mortem changes to be followed. During and after the simulated death, changes in levels of pH and in content of energy-rich compounds
were observed with 31P NMRS. Our results showed an inverse linear relationship between pH and lactate in each of the three rabbits (r = 0.93, P < 0.001; r = 0.92, P < 0.01; r = 0.89, P < 0.01) and a decrease in phosphocreatine and concomitant increase in lactate. We then investigated whether this sequence
allowed repeated detection of lactate in human soleus muscle during the recovery between periods of intense exercise (force-velocity
test, F-v test). Seven subjects mean age 25.1 (SEM 0.8) years participated in this study. Soleus muscle lactate was detected at rest
and for 3 min 30 s of the 5-min recovery between periods using a 2.35-T 40-cm bore magnet spectrometer. Arm venous plasma
lactate concentration was measured at rest, during the F-v test when the subject stopped pedalling (S1), and at the end of each 5-min recovery between periods (S2). Results showed that the venous plasma lactate concentration at S1 and S2 increased significantly from the beginning of the F-v test to peak anaerobic power (W
an,peak) (P < 0.001). The spectra showed that muscle lactate resonance intensity rose markedly when W
an,peak was achieved. The muscle lactate resonance intensity plotted as a percentage of the resting value increased significantly
at W
an,peak compared with submaximal braking forces (P < 0.05). We concluded from these results that localized 1H NMRS using STEAM with a long t
m allows suppression of the fat signal and repeated detection of lactate on isolated perfused skeletal muscle in animals and
between periods of intense exercise in humans.
Accepted: 19 January 1998 相似文献
8.
Michael Gleeson Andrew K. Blannin Neil P. Walsh Christine N. E. Field Jeanette C. Pritchard 《European journal of applied physiology and occupational physiology》1998,77(3):292-295
Eccentric muscle actions are known to induce temporary muscle damage, delayed onset muscle soreness (DOMS) and muscle weakness
that may persist for several days. The purpose of the present study was to determine whether DOMS-inducing exercise affects
blood lactate responses to subsequent incremental dynamic exercise. Physiological and metabolic responses to a standardised
incremental exercise task were measured two days after the performance of an eccentric exercise bout or in a control (no prior
exercise) condition. Ten healthy recreationally active subjects (9 male, 1 female), aged 20 (SD 1) years performed repeated
eccentric muscle actions during 40 min of bench stepping (knee high step; 15 steps · min−1). Two days after the eccentric exercise, while the subjects experienced DOMS, they cycled on a basket loaded cycle ergometer
at a starting work rate of 150 W, with increments of 50 W every 2 min until fatigue. The order of the preceding treatments
(eccentric exercise or control) was randomised and the treatments were carried out 2 weeks apart. Two days after the eccentric
exercise, all subjects reported leg muscle soreness and exhibited elevated levels of plasma creatine kinase activity (P < 0.05). Endurance time and peak V˙O2 during cycling were unaffected by the prior eccentric exercise. Minute volume, respiratory exchange ratio and heart rate
responses were similar but venous blood lactate concentration was higher (P < 0.05) during cycling after eccentric exercise compared with the control condition. Peak blood lactate concentration, observed
at 2 min post-exercise was also higher [12.6 (SD 1.4) vs 10.9 SD (1.3) mM; P < 0.01]. The higher blood lactate concentration during cycling exercise after prior eccentric exercise may be attributable
to an increased rate of glycogenolysis possibly arising from an increased recruitment of Type II muscle fibres. It follows
that determination of lactate thresholds for the purpose of fitness assessment in subjects experiencing DOMS is not appropriate.
Accepted: 27 September 1997 相似文献
9.
Shizue Masuki John H Eisenach William G Schrage Christopher P Johnson Niki M Dietz Brad W Wilkins Paola Sandroni Phillip A Low Michael J Joyner 《Journal of applied physiology》2007,103(4):1128-1135
Postural tachycardia syndrome (POTS) is characterized by excessive tachycardia without hypotension during orthostasis. Most POTS patients also report exercise intolerance. To assess cardiovascular regulation during exercise in POTS, patients (n = 13) and healthy controls (n = 10) performed graded cycle exercise at 25, 50, and 75 W in both supine and upright positions while arterial pressure (arterial catheter), heart rate (HR; measured by ECG), and cardiac output (open-circuit acetylene breathing) were measured. In both positions, mean arterial pressure, cardiac output, and total peripheral resistance at rest and during exercise were similar in patients and controls (P > 0.05). However, supine stroke volume (SV) tended to be lower in the patients than controls at rest (99 +/- 5 vs. 110 +/- 9 ml) and during 75-W exercise (97 +/- 5 vs. 111 +/- 7 ml) (P = 0.07), and HR was higher in the patients than controls at rest (76 +/- 3 vs. 62 +/- 4 beats/min) and during 75-W exercise (127 +/- 3 vs. 114 +/- 5 beats/min) (both P < 0.01). Upright SV was significantly lower in the patients than controls at rest (57 +/- 3 vs. 81 +/- 6 ml) and during 75-W exercise (70 +/- 4 vs. 94 +/- 6 ml) (both P < 0.01), and HR was much higher in the patients than controls at rest (103 +/- 3 vs. 81 +/- 4 beats/min) and during 75-W exercise (164 +/- 3 vs. 131 +/- 7 beats/min) (both P < 0.001). The change (upright - supine) in SV was inversely correlated with the change in HR for all participants at rest (R(2) = 0.32), at 25 W (R(2) = 0.49), 50 W (R(2) = 0.60), and 75 W (R(2) = 0.32) (P < 0.01). These results suggest that greater elevation in HR in POTS patients during exercise, especially while upright, was secondary to reduced SV and associated with exercise intolerance. 相似文献
10.
McInnis MD Newhouse IJ von Duvillard SP Thayer R 《European journal of applied physiology and occupational physiology》1998,79(1):99-105
The purpose of this study were: (1) to establish the prevalence of exercise-induced hematuria in a group of otherwise healthy
male runners (n = 70), and (2) to investigate the role of exercise intensity in those runners who exhibited exercise-related hematuria (n = 10) by evaluating the effect of running and cycling at high and low intensities. The identified and recruited subjects
participated in four different exercise protocols: (1) a 60-min treadmill run (RUN) at 90% of anaerobic threshold (Thae), (2) a 60-min leg cycle ergometer ride (BIKE) at 90% of Thae, (3) a 3×400-m sprint (SPRINT), each followed by 4 min of rest or light walking, and (4) 3×60-Wingate leg cycle ergometry
tests, each followed by 4 min of rest or light cycling. The study employed a 3×4 (time by protocol) within-subjects design
and dependent variables were measured before exercise, 4 min after, and 1 h after exercise, and included measurements of hematuria,
proteinuria, urinary pH, serum haptoglobin concentration, serum creatine phosphokinase activity, plasma lactate concentration,
and hemoglobin. The 400-m sprint at maximal effort significantly increased both hematuria and proteinuria (P < 0.01). Post-exercise hematuria for the SPRINT protocol was significantly different than that for the BIKE (P < 0.01) and RUN (P < 0.01) protocols. Due to the significant increase in hematuria and proteinuria following the SPRINT protocol, it was concluded
that exercise-related changes in renal function were associated with weight-bearing exercise intensity rather than non-weight-bearing
exercise duration.
Accepted: 30 April 1998 相似文献
11.
N. J. Lynch M. A. Nimmo 《European journal of applied physiology and occupational physiology》1998,78(6):565-572
Five women using low-dose, monophasic oral contraceptive (OC) agents (OC group) and ten normally menstruating women (Non-OC
group) performed a treadmill protocol to determine the effect of OCs and the menstrual cycle (MC) on intermittent exercise
performance and some commonly used metabolic markers. The Non-OC group were tested once in the mid-follicular phase (MFP)
and once in the late luteal phase (LLP) of the MC, while the OC group performed their first test within 1 week of taking the
OC (T1) and their second test 1 week later (T2). Despite performance time being the same in both groups [mean (SD), Non-OC
group: 77.7 (14.9) s versus OC group: 77.7 (21.1)s], plasma ammonia concentration ([NH3]pl) was higher in the Non-OC group when compared to the OC group throughout recovery (P < 0.05). No differences were found in blood lactate (BLa), maximum heart rate or aural temperature (T
au) between groups. Within the Non-OC group T
au increased with exercise in both phases (P < 0.05), however T
au was higher in the LLP at rest [36.1 (0.3)°C) and 1 min post-exercise [37.1 (0.6)°C), when compared to the MFP [35.8 (0.3)
and 36.9 (0.7)°C, rest and 1 min post-exercise respectively, P < 0.05]. Within the OC group T1 resulted in a higher peak BLa [11.2 (0.4) mmol/l] and [NH3]pl (143.0 (26.2) Umol/l] when compared to T2 [BLa, 9.6 (0.9); [NH3], 119.4 (48.1), P<0.05]. These results suggest that: (1) exercise performance does not vary between the MFP and the LLP of the MC, nor does
it appear to be affected by the number of days using the OC, and (2) an altered metabolism occurs both between groups (Non-OC
versus OC) and within the OC group.
Accepted: 2 June 1998 相似文献
12.
H. Hebestreit O. Bar-Or 《European journal of applied physiology and occupational physiology》1998,78(1):7-12
Heart rate (HR) monitoring is commonly used to assess 24-h energy expenditure (EE) in children but it has been found to overestimate
the true values. One reason for this may be the effect of climatic heat stress on HR. An equation has been previously developed
to adjust HR measured during continuous exercise for the influence of climate. Since play in children is rarely of a continuous
pattern, one objective of this study was to compare the effects of climatic heat stress on the HR response to intermittent
and to continuous exercise. A second objective was to determine whether the previously developed equation is suitable for
intermittent exercise. A group of 12 boys and 8 girls (aged 8–11 years) cycled in a climatic chamber. The exercise consisted
of continuous cycling for 5 min at 35%, 55%, and 75% of peak oxygen up take (random order) followed by alternating cycling
at the same resistance and cadence (30 s) and rest (30 s) for 3 additional min. The oxygen uptake (V˙O2) and HR were determined for 2 min at the end of continuous cycling and for 2 min during intermittent cycling. Climatic conditions
(randomly assigned) were dry bulb temperature T
db 22°C, 50% relative humidity (rh); T
db 28°C, 55% rh; T
db 32°C, 52% rh; or T
db 35°C, 58% rh. The difference between HR measured at a given T
db (HRmeas) and HR at 22°C and at the same V˙O2 was then calculated (ΔHR). The ΔHR increased linearly with increasing temperature but was not related to V˙O2 or to exercise type. However, a small but significant difference was found if the published equation was used with data from
intermittent exercise. The accuracy of the existing equation adjusting HRmeas for the influence of T
db (HRcorr) could be improved to HRcorr= HRmeas · (1.18308−(0.0083218 · T
db)). In conclusion, the effects of climatic heat stress on HR were similar in continuous and intermittent exercise, and HR
can be adjusted for the influence of climate in groups of pre- and early pubertal children during rest, intermittent and continuous
exercise at ambient temperatures between 22°C and 35°C, thereby reducing the error in predicting EE from HR.
Accepted: 13 January 1998 相似文献
13.
John L. Azevedo Jr. Jon K. Linderman Steven L. Lehman George A. Brooks 《European journal of applied physiology and occupational physiology》1998,78(6):479-486
The present study was undertaken to determine the effects of endurance training on glycogen kinetics during exercise. A new
model describing glycogen kinetics was applied to quantitate the rates of synthesis and degradation of glycogen. Trained and
untrained rats were infused with a 25% glucose solution with 6-3H-glucose and U-14C-lactate at 1.5 and 0.5 μCi · min−1 (where 1 Ci = 3.7 × 1010 Bq), respectively, during rest (30 min) and exercise (60 min). Blood samples were taken at 10-min intervals starting just
prior to isotopic infusion, until the cessation of exercise. Tissues harvested after the cessation of exercise were muscle
(soleus, deep, and superficial vastus lateralis, gastrocnemius), liver, and heart. Tissue glycogen was quantitated and analyzed
for incorporation of 3H and 14C via liquid scintillation counting. There were no net decreases in muscle glycogen concentration from trained rats, whereas
muscle glycogen concentration decreased to as much as 64% (P < 0.05) in soleus in muscles from untrained rats after exercise. Liver glycogen decreased in both trained (30%) and untrained
(40%) rats. Glycogen specific activity increased in all tissues after exercise indicating isotope incorporation and, thus,
glycogen synthesis during exercise. There were no differences in muscle glycogen synthesis rates between trained and untrained
rats after exercise. However, training decreased muscle glycogen degradation rates in total muscle (i.e., the sum of the degradation
rates of all of the muscles sampled) tenfold (P < 0.05). We have applied a model to describe glycogen kinetics in relation to glucose and lactate metabolism during exercise
in trained and untrained rats. Training significantly decreases muscle glycogen degradation rates during exercise.
Accepted: 22 May 1998 相似文献
14.
Nigel A. S. Taylor Mark J. Patterson James D. Cotter Duncan J. Macfarlane 《European journal of applied physiology and occupational physiology》1997,76(4):380-386
The influence of artificially induced anaemia on thermal strain was evaluated in trained males. Heat stress trials (38.6°C,
water vapour pressure 2.74 kPa) performed at the same absolute work rates [20 min of seated rest, 20 min of cycling at 30%
peak aerobic power (V˙O2peak), and 20 min cycling at 45% V˙O2peak] were completed before (HST1) and 3–5 days after 3 units of whole blood were withdrawn (HST2). Mild anaemia did not elevate
thermal strain between trials, with auditory canal temperatures terminating at 38.5°C [(0.16), HST1] and 38.6°C [(0.13), HST2;
P > 0.05]. Given that blood withdrawal reduced aerobic power by 16%, this observation deviates from the close association often
observed between core temperature and relative exercise intensity. During HST2, the absolute and integrated forearm sweat
rate (m˙
sw) exceeded control levels during exercise (P < 0.05), while a suppression of forehead m˙
sw occurred (P < 0.05). These observations are consistent with a possible peripheral redistribution of sweat secretion. It was concluded
that this level of artificially induced anaemia did not impact upon heat strain during a 60-min heat stress test.
Accepted: 17 April 1997 相似文献
15.
D. L. Thompson K. M. Townsend R. Boughey K. Patterson D. R. Bassett Jr 《European journal of applied physiology and occupational physiology》1998,78(1):43-49
Substrate utilization during and after low- and moderate-intensity exercise of similar caloric expenditure was compared.
Ten active males [age: 26.9 (4.8) years; height: 181.1 (4.8) cm; Mass: 75.7 (8.8) kg; maximum O2 consumption (V˙O2
max
): 51.2 (4.8) ml · kg−1 · min−1] cycled at 33% and 66% V˙O2
max
on separate days for 90 and 45 min, respectively. After exercise, subjects rested in a recumbent position for 6 h. Two h
post-exercise, subjects ate a standard meal of 66% carbohydrate (CHO), 11% protein, and 23% fat. Near-continuous indirect
calorimetry and measurement of urinary nitrogen excretion were used to determine substrate utilization. Total caloric expenditure
was similar for the two trials; however, significantly (P<0.05) more fat [42.4 (3.6) g versus 24.0 (12.2) g] and less CHO [142.5 (28.5) g versus 188.8 (45.2) g] was utilized as a
substrate during the low-intensity compared to the moderate-intensity trial. Protein utilization was similar for the two trials.
The difference in substrate use can be attributed to the exercise period because over twice as much fat was utilized during
low-intensity [30.0 (11.0) g] compared to moderate-intensity exercise [13.6 (6.6) g]. Significantly more (P<0.05) CHO was utilized during the moderate-intensity [106.0 (27.8) g] compared to the low-intensity exercise [68.7 (20.0) g].
Substrate use during the recovery period was not significantly different. We conclude that low-intensity, long-duration exercise
results in a greater total fat oxidation than does moderate intensity exercise of similar caloric expenditure. Dietary-induced
thermogenesis was not different for the two trials.
Accepted: 3 November 1997 相似文献
16.
A.-W. Pan J. He Y. Kinouchi Hisao Yamaguchi Hiroshi Miyamoto 《European journal of applied physiology and occupational physiology》1997,75(5):388-395
The present study investigated the mechanism of diving bradycardia. A group of 14 healthy untrained male subjects were examined
during breath-holding either out of the water (30–33°C), in head-out immersion, or in whole-body submersion (27–29°C) in a
diving pool. Blood velocity, blood volume flow in the carotid artery, diastolic blood pressure and electrocardiogram were
measured and recorded during the experiments. The peak blood velocity increased by 13.6% (P < 0.01) and R-wave amplitude increased by 57.1% (P < 0.005) when the subjects entered water from air. End-diastolic blood velocity in the carotid artery increased significantly during breath-holding, e.g. increased from 0.20 (SD 0.02) m · s−1 at rest to 0.33 (SD 0.04) m · s−1 (P < 0.001) at 50.0 s in breath-hold submersion to a 2.0-m depth. Blood volume flow in the carotid artery increased by 26.6%
(P < 0.05) at 30 s and 36.6% (P < 0.001) at 40 s in breath-hold submersion to a 2.0-m depth. Diastolic blood pressure increased by 15.4% (P < 0.01) at 60 s during breath-holding in head-out immersion. Blood volume flow, and diastolic blood pressure increased significantly more and faster during breath-holding in submersion than out of the
water. There was a good negative correlation with the heart rate: the root mean square correlation coefficient r was 0.73 (P < 0.001). It was concluded that an increased accumulation of blood in the aorta and arteries at end-diastole and decreased
venous return, caused by an increase in systemic peripheral resistance during breath-holding, underlies diving bradycardia.
Accepted: 22 November 1996 相似文献
17.
Response of plasma IL-6 and its soluble receptors during submaximal exercise to fatigue in sedentary middle-aged men 下载免费PDF全文
The pleiotropic cytokine interleukin-6 (IL-6) has been demonstrated to increase during exercise. Little is known regarding
the response of the soluble IL-6 receptors (sIL-6R and sgp130) during such exercise. The aim of the current study was to investigate
the response of plasma IL-6, sIL-6R and sgp130 during fatiguing submaximal exercise in humans. Twelve participants underwent
an incremental exercise test to exhaustion and one week later performed a submaximal exercise bout (96 ± 6% lactate threshold)
to volitional exhaustion. Blood samples taken at rest and immediately post exercise were analyzed for IL-6, sIL-6R and sgp130.
IL-6 increased (P < 0.01) by 8.4 ± 8.9 pg ml−1 (75.7%) during the exercise period. sIL-6R and sgp130 also increased (P < 0.05) by 2.7 ± 3.9 ng ml−1 (9.6%) and 37.7 ± 55.6 ng ml−1 (9.6%), respectively. The current study is the first investigation to demonstrate that alongside IL-6, acute exercise stress
results in an increase in both sIL-6R and sgp130. 相似文献
18.
Patrick Mucci Jacques Prioux Maurice Hayot Michèle Ramonatxo Christian Préfaut 《European journal of applied physiology and occupational physiology》1998,77(4):343-351
Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyper- pnoea. The aim of this
study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation
of the central chemoreceptors. The ventilation response to CO2 was measured in nine elderly untrained men (UT) [mean age 66.3 (SEM 3.1) years] and nine master athletes (MA) [mean age 62.7
(SEM 0.8) years] at rest, during moderate exercise (40% maximal oxygen uptake, V˙O2max), and during strenuous exercise (70% V˙O2max) using the rebreathing method. Our results showed that the ventilation response to CO2 did not differ with endurance training and/or exercise, that the threshold of the CO2 response (Th) increased with exercise (P < 0.001), that the increase in Th in MA was higher than in UT between rest and moderate exercise [ΔTh0–40: 8.55 (SEM 1.8) vs 3.06 (SEM 1.72) mmHg, P < 0.05], and that ΔTh0–40 and Th during moderate exercise were negatively correlated with arterial O2 saturation during maximal exercise (r = 0.50, P<0.05). We concluded therefore that exercise-induced hypoxaemia in master athletes may not be due to a lower ventilation response
to CO2, but may be partly related to a greater increase in Th during moderate exercise.
Accepted: 18 August 1997 相似文献
19.
K. J. Atkins M. W. Thompson J. J. Ward P. T. Kelly 《European journal of applied physiology and occupational physiology》1997,76(4):352-355
The purpose of this investigation was to measure expired air temperature under cool- and hot-humid environmental conditions
at rest and during prolonged exercise to: (1) establish if significant increases in body core temperature affected expired
air temperature, and (2) to determine if the temperature setting for heating the pneumotachometer in an open-circuit system
requires adjustment during prolonged exercise tests to account for changes in expired air temperature. Six male distance runners
completed two tests in cool-humid [dry bulb temperature (T
db) 15.5 (SD 1.3)°C, wet bulb temperature (T
wb) 12.1 (SD 1.4)°C] and hot-humid [T
db 31.6 (SD 0.6)°C, T
wb 24.9 (SD 0.6)°C, black globe temperature (T
g) 34.3 (SD 0.3)°C] environments, running at a velocity corresponding to 65% [67.1 (SD 2.82)%] of their maximal oxygen uptake.
Rectal temperature and expired air temperatures were compared at rest, and after 30 min and 60 min of exercise for each environment.
The main finding of this investigation was a significant (P < 0.05) but small increase in expired air temperature between the 30-min and 60-min measures in the hot-humid environment.
No significant differences in expired air temperature were found between the 30-min and 60-min measures in the cool-humid
environment. These findings suggest that: (1) expired air temperature is influenced by elevations in body core temperature
during prolonged exercise in hot-humid conditions, and (2) that the temperature setting for heating the head of the pneumotachometer
(after determining the appropriate temperature through measuring expired air temperature for the set environmental condition)
may require adjustment during prolonged exercise trials in hot-humid environmental conditions.
Accepted: 27 February 1997 相似文献
20.
Isabelle Sendowski Gustave Savourey Yves Besnard Jacques Bittel 《European journal of applied physiology and occupational physiology》1997,75(6):471-477
To study the physiological responses induced by immersing in cold water various areas of the upper limb, 20 subjects immersed
either the index finger (T1), hand (T2) or forearm and hand (T3) for 30 min in 5°C water followed by a 15-min recovery period.
Skin temperature of the index finger, skin blood flow (Qsk) measured by laser Doppler flowmetry, as well as heart rate (HR) and mean arterial blood pressure (ˉBPa) were all monitored during the test. Cutaneous vascular conductance (CVC) was calculated as Qsk / ˉBPa. Cold induced vasodilatation (CIVD) indices were calculated from index finger skin temperature and CVC time courses. The
results showed that no differences in temperature, CVC or cardiovascular changes were observed between T2 and T3. During T1,
CIVD appeared earlier compared to T2 and T3 [5.90 (SEM 0.32) min in T1 vs 7.95 (SEM 0.86) min in T2 and 9.26 (SEM 0.78) min
in T3, P < 0.01]. The HR was unchanged in T1 whereas it increased significantly at the beginning of T2 and T3 [+13 (SEM 2) beats · min−1 in T2 and +15 (SEM 3) beats · min−1 in T3, P < 0.01] and then decreased at the end of the immersion [−12 (SEM 3) beats · min−1 in T2, and −15 (SEM 3) beats · min−1 in T3, P < 0.01]. Moreover, ˉBPaincreased at the beginning of T1 but was lower than in T2 and T3 [+9.3 (SEM 2.5) mmHg in T1, P < 0.05; +20.6 (SEM 2.6) mmHg and 26.5 (SEM 2.8) mmHg in T2 and T3, respectively, P < 0.01]. The rewarming during recovery was faster and higher in T1 compared to T2 and T3. These results showed that general
and local physiological responses observed during an upper limb cold water test differed according to the area immersed. Index
finger cooling led to earlier and faster CIVD without significant cardiovascular changes, whereas hand or forearm immersion
led to a delayed and slower CIVD with a bradycardia at the end of the test.
Accepted: 26 November 1996 相似文献