共查询到20条相似文献,搜索用时 390 毫秒
1.
Yang Hu Katsumi Asano Koh Mizuno Satoshi Usuki Youko Kawakura 《European journal of applied physiology and occupational physiology》1998,78(5):417-421
The purpose of this study was to compare the effects of continuous and intermittent exercise training on serum testosterone
[T] and corticosterone concentrations [Cort] during normoxia and hypobaric hypoxia. Male rats swam with loads of 3% (normoxia)
or 2.25% (462 mmHg) body mass for 60 min in the continuous training groups, and 15 min separated by a 7-min rest × 4, with
60-min total exercise duration in the intermittent training groups, 5␣days · week−1 for 6 weeks. Serum [T] were measured at␣rest and following exercise after 6 weeks of training. Serum [Cort] were measured
immediately after an acute period of exercise or after 6 weeks of training at rest and following exercise. Continuous exercise
induced decreases in [T] under both conditions. Intermittent exercise showed a tendency to increase [T] during normoxia, but
caused a suppression during hypobaric hypoxia. The [Cort] was elevated by a similar margin after an acute period of exercise
during both conditions. After 6 weeks of training, however, [Cort] increased slightly after exercise during normoxia. A lower
resting [Cort], which was increased after exercise, was found in the training groups during hypoxia. No relevant relationship
was found between the behaviours of [T] and [Cort] after exercise during either conditions.
Accepted: 20 April 1998 相似文献
2.
Jay R. Hoffman Nicholas A. Ratamess Christopher P. Tranchina Stefanie L. Rashti Jie Kang Avery D. Faigenbaum 《Amino acids》2010,38(3):771-778
The effect of 42 g of protein ingested pre- and post-exercise on recovery from an acute resistance exercise session was examined
in 15 male strength/power athletes who were randomly divided into a supplement (SUP) or placebo (PL) group. Subjects reported
to the Human Performance Laboratory (HPL) on four separate occasions (T1–T4). Maximal strength [one repetition-maximum (1-RM)]
testing was performed during T1. During T2 subjects performed four sets of ten repetitions at 80% of their 1-RM in the squat,
dead lift and barbell lunge exercises with 90 s of rest between each set. Blood draws occurred at baseline (BL), immediate
and 15 min post-exercise to determine testosterone, cortisol and creatine kinase (CK) concentrations. Subjects reported back
to the HPL 24 (T3) and 48 h (T4) post-exercise for a BL blood draw and to perform four sets of ten repetitions with 80% of
1-RM for the squat exercise only. No differences in the number of repetitions performed in the squat exercise were seen between
the groups at T2. Relative to T2, PL performed significantly (P < 0.05) fewer repetitions than SUP at T3 and T4 (−9.5 ± 5.5 repetitions vs. −3.3 ± 3.6 during T3, respectively, and −10.5 ± 8.2
repetitions vs. −2.3 ± 2.9 repetitions during T4, respectively). No differences in hormonal measures were seen between the
groups. CK concentrations were significantly (P < 0.05) elevated at T3 for both groups, but continued to elevate (P < 0.05) at T4 for PL only. No significant group differences were noted for CK at any time point. Results indicate that a
proprietary protein SUP consumed before and after a resistance training session significantly contributes to improvements
in exercise recovery 24 and 48 h post-exercise. 相似文献
3.
Teemu Pullinen Antti Mero Ewen MacDonald Arto Pakarinen Paavo V. Komi 《European journal of applied physiology and occupational physiology》1998,77(5):413-420
The plasma noradrenaline (NA) and adrenaline (A) concentration responses of seven young male athletes [15 (SD 1) years] and
seven adult male athletes [25 (SD 6) years] were investigated together with the serum testosterone (Tes) concentration responses
in four different half-squatting exercises. The loads, number of repetitions, exercise intensity and recovery between the
sets were manipulated such that different types of metabolic demand could be expected. However, the amount of work done was
kept equal in each kind of exercise. After the most exhausting unit of exercise (E3; two sets of 30 repetitions with 50% of
1 repetition maximum and with 2-min recovery between the sets) the plasma NA concentration was significantly lower in the
younger than in the adult subjects [15.7 (SD 7.8) vs 32.7 (SD 13.2) nmol · l−1, P < 0.05], while the A concentrations were similar. In the other three exercises no differences in the plasma catecholamine
concentration responses among the groups were observed. The postexercise Tes concentrations, however, were significantly lower
in the younger than in the adult subjects in every exercise unit. No correlations between the plasma catecholamine and serum
Tes concentration responses were observed in any of the exercise units in either group. The results of the present study may
suggest reduced sympathetic nervous activity in the younger subjects compared to the adults in response to exhausting resistance
exercise. The results may also suggest that the catecholamines were less involved in eliciting an increase in Tes secretion
in these resistance exercises.
Accepted: 11 November 1997 相似文献
4.
Elizabeth A. Flaherty Merav Ben-David Winston P. Smith 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(7):1067-1078
Gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. To assess costs
of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to
measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise
oxygen consumption for nine northern flying squirrels (Glaucomys sabrinus) and four fox squirrels (Sciurus niger). Our results indicate that oxygen consumption during exercise by flying squirrels was 1.26–1.65 times higher than predicted
based on body mass, and exponentially increased with velocity (from 0.84 ± 0.03 ml O2 kg−1 s−1 at 0.40 m s−1 to 1.55 ± 0.03 ml O2 kg−1 s−1 at 0.67 m s−1). Also, cost of transport in flying squirrels increased with velocity, although excess exercise oxygen consumption and excess
post-exercise oxygen consumption did not. In contrast, oxygen consumption during exercise for fox squirrels was similar to
predicted, varying from 0.51 (±0.02) ml O2 kg−1 s−1 at 0.63 m s−1 to 0.54 (±0.03) ml O2 kg−1 s−1 at 1.25 m s−1. In addition, the cost of transport for fox squirrels decreased with velocity, while excess exercise oxygen consumption and
excess post-exercise oxygen consumption did not. Collectively, these observations suggest that unlike fox squirrels, flying
squirrels are poorly adapted to prolonged bouts of quadrupedal locomotion. The evolution of skeletal adaptations to climbing,
leaping, and landing and the development of a gliding membrane likely has increased the cost of quadrupedal locomotion by
>50% while resulting in energy savings during gliding and reduction in travel time between foraging patches. 相似文献
5.
Ke-Gui Li Zhen-Dong Cao Jiang-Lan Peng Shi-Jian Fu 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(5):661-671
Feeding and exhaustive exercise are known to elevate metabolism. However, acid–base status may be oppositely affected by the
two processes. In this study, we first investigated the acid–base response of Chinese catfish to feeding (the meal size was
about 8% of body mass) to test whether an alkaline tide (a metabolic alkalosis created by gastric HCl secretion after feeding)
would occur. We then determined the combined effects of feeding and exhaustive exercise on excess post-exercise oxygen consumption
and acid–base status to determine whether the alkaline tide induced by feeding protects against acid–base disturbance during
exhaustive exercise and affects subsequent recovery. Arterial blood pH increased from 7.74 ± 0.02 before feeding to 7.88 ± 0.02
and plasma [HCO3
−]pl increased from 5.42 ± 0.29 to 7.83 ± 0.37 mmol L−1 6 h after feeding, while feeding had no significant effect on
P\textCO2 P_{{{\text{CO}}_{2} }} . Exhaustive exercise led to a significant reduction in pH by 0.46 units and a reduction of [HCO3
−]pl by ~3 mmol L−1. Lactate concentrations in white muscle and plasma increased by 2.4 mmol L−1 and 13.4 μmol g−1, respectively. Fed fish had a higher pH and [HCO3
−]pl than fasting fish at rest, and the reductions in pH (0.36 units) and [HCO3
−]pl (~2 mmol L−1) were thus lower after exhaustive exercise. However, the recovery of acid–base status and metabolites were similar in digesting
and fasting fish. Overall, a significant alkaline tide was found in Chinese catfish after feeding. The alkaline tide elicited
by feeding significantly prevented the decreases in pH and [HCO3
−]pl immediately after exhaustive exercise, but recovery from exhaustive exercise was not affected by digestion. 相似文献
6.
J. Langfort R. Zarzeczny W. Pilis K. Nazar H. Kaciuba-Ucitko 《European journal of applied physiology and occupational physiology》1997,76(2):128-133
The aim of this study was to find out whether a low-carbohydrate diet (L-CHO) affects: (1) the capacity for all-out anaerobic
exercise, and (2) hormonal and metabolic responses to this type of exercise. To this purpose, eight healthy subjects underwent
a 30-s bicycle Wingate test preceded by either 3 days of a controlled mixed diet (130 kJ/kg of body mass daily, 50% carbohydrate,
30% fat, 20% protein) or 3 days of an isoenergetic L-CHO diet (up to 5% carbohydrate, 50% fat, 45% protein) in a randomized
order. Before and during 1 h after the exercise venous blood samples were taken for measurement of blood lactate (LA), β-hydroxybutyrate
(β-HB), glucose, adrenaline (A), noradrenaline (NA) and insulin levels. Oxygen consumption (V˙O2) was also determined. It was found that the L-CHO diet diminished the mean power output during the 30-s exercise bout [533
(7) W vs 581 (7) W, P < 0.05] without changing the maximal power attained during the first or second 5-s interval of the exercise. In comparison
with the data obtained after the consumption of a mixed diet, after the consumption of a L-CHO diet resting plasma concentrations
of β-HB [2.38 (0.18) vs 0.23 (0.01) mmol · l−1, P < 0.001] and NA [4.81 (0.68) vs 2.2 (0.31) nmol · l−1, P < 0.05] were higher, while glucose [4.6 (0.1) vs 5.7 (0.2) mmol · l−1, P < 0.05] and insulin concentrations [11.9 (0.9) vs 21.8 (1.8) mU · l−1] were lower. The 1-h post-exercise excess of V˙O2 [9.1 (0.25) vs 10.6 (0.25) l, P < 0.05], and blood LA measured 3 min after the exercise [9.5 (0.4) vs 10.6 (0.5) mmol · l−1, P < 0.05] were lower following the L-CHO treatment, whilst plasma NA and A concentrations reached higher values [2.24 (0.40) vs
1.21 (0.13) nmol · l−1 and 14.30 (1.41) vs 8.20 (1.31) nmol · l−1, P < 0.01, respectively]. In subjects on the L-CHO diet, the plasma β-HB concentration decreased quickly after exercise, attaining
≈30% of the pre-exercise value within 60 min, while insulin and glucose levels were elevated. The main conclusions of this
study are: (1) a L-CHO diet is detrimental to anaerobic work capacity, possibly because of a reduced muscle glycogen store
and decreased rate of glycolysis; (2) reduced carbohydrate intake for 3 days enhances activity of the sympathoadrenal system
at rest and after exercise.
Accepted: 31 January 1997 相似文献
7.
Kendrick IP Harris RC Kim HJ Kim CK Dang VH Lam TQ Bui TT Smith M Wise JA 《Amino acids》2008,34(4):547-554
Carnosine (Carn) occurs in high concentrations in skeletal muscle is a potent physico-chemical buffer of H+ over the physiological range. Recent research has demonstrated that 6.4 g.day−1 of β-alanine (β-ala) can significantly increase skeletal muscle Carn concentrations (M-[Carn]) whilst the resultant change
in buffering capacity has been shown to be paralleled by significant improvements in anaerobic and aerobic measures of exercise
performance. Muscle carnosine increase has also been linked to increased work done during resistance training. Prior research
has suggested that strength training may also increase M-[Carn] although this is disputed by other studies. The aim of this
investigation is to assess the effect of 10 weeks resistance training on M-[Carn], and, secondly, to investigate if increased
M-[Carn] brought about through β-ala supplementation had a positive effect on training responses. Twenty-six Vietnamese sports
science students completed the study. The subjects completed a 10-week resistance-training program whilst consuming 6.4 g.day−1 of β-ala (β-ALG) or a matched dose of a placebo (PLG). Subjects were assessed prior to and after training for whole body
strength, isokinetic force production, muscular endurance, body composition. β-Alanine supplemented subjects increased M-[Carn]
by 12.81 ± 7.97 mmol.kg−1 dry muscle whilst there was no change in PLG subjects. There was no significant effect of β-ala supplementation on any of
the exercise parameters measured, mass or % body fat. In conclusion, 10 weeks of resistance training alone did not change
M-[Carn]. 相似文献
8.
Emanuelli M Cecati M Sartini D Stortoni P Corradetti A Giannubilo SR Turi A Tranquilli AL 《Cell stress & chaperones》2009,14(2):193-197
AHSP inhibits cellular production of the reactive oxygen species. Reduced AHSP indicates reduced protection against oxidative
stressors. Our objective was to investigate AHSP levels in recurrent miscarriage (RM). Trophoblast was collected from women
of 10 weeks gestation: voluntary abortion controls (VA, n = 10); spontaneous first miscarriage with subsequent normal pregnancy (SMSN, n = 15) or with subsequent miscarriage (SMSM, n = 5); RM previously investigated (RMPS, n = 5) or not previously investigated (RM, n = 5). AHSP mRNA and protein were determined using real-time quantitative polymerase chain reaction (PCR) and Western blot,
respectively. One-way ANOVA was performed to assess statistical significance (p < 0.05). ahsp mRNA levels were maximally reduced in RM and RMPS (8.0 × 10−6 ± 1.3 and 8.1 × 10−6 ± 0.7, respectively) compared with SMSN and VA (16.1 × 10−6 ± 2.3 and 26.1 × 10−6 ± 2.7, respectively). SMSM showed levels significantly reduced as well (9.0 × 10−6 ± 2.3). In RM, a reduced defense from oxidative stressors is evident at first miscarriage, identifying women at high risk
for subsequent eventful pregnancy. Reduced AHSP may identify women at risk of experiencing further miscarriages.
Monica Emanuelli and Monia Cecati contributed equally to this paper. 相似文献
9.
The effect of time of day and exercise on platelet functions and platelet–neutrophil aggregates in healthy male subjects 总被引:2,自引:0,他引:2
Platelet activation state changes by exercise. The effect of exercise time on platelet activation state and formation of platelet–neutrophil
aggregates are not known yet. In this study the effect of exercise and time of day were examined on platelet activity with
platelet–neutrophil aggregates. Ten moderately active males aged 27± 1.63 (mean±S.D.) years completed sub-maximal (70% VO2max) exercise trials for 30 min. Blood pressure (BP) was recorded. Venous blood samples were obtained at rest, immediately post-exercise
and after 30 min of recovery. Whole blood was analysed for haematocrit (Hct), haemoglobin (Hb), platelet count (PC), mean
platelet count (MPV) and platelet aggregation (PA). Platelet–neutrophil aggregates and beta-thromboglobulin (β-TG) levels
were assayed. Platelet count showed significant increase after morning exercise ((236± 32)×109 l−1 versus (202± 34)×109 l−1 baseline, p < 0.05). Exercise resulted in significantly lower MPV after the evening exercise (9.16± 0.5 fl versus 9.65± 0.36 fl, p < 0.05). Platelet aggregation by adenosine diphosphate (ADP) decreased after morning exercise and the recovery aggregation
levels were significantly different at two different times of the day (68± 20% a.m. versus 80± 12% p.m., p < 0.05). It was also showed that platelet–neutrophil aggregates increased significantly from baseline after both exercises.
Exercise-induced platelet–neutrophil aggregates were higher in the evening (10.7± 1.3% p.m. versus 6.4± 1.8% a.m., p < 0.0001). It is therefore concluded that besides platelet–platelet aggregation, exercise can cause platelet– neutrophil
aggregates. In addition, time of day has an effect on platelet activation related events. Circadian variations of physiological
parameters may have an effect on thrombus formation by platelet activation. (Mol Cell Biochem xxx: 119–124, 2005) 相似文献
10.
Synopsis Blood samples from cannulated young adult (2.5–15 kg) white sturgeon, acclimated to San Francisco Bay water (24 ppt) had plasma
values of 248.8 ± 13.5 mOsm kg−1 H2O, [Na+] = 125 ± 8.0 mEq 1−1, [K+] = 2.6 ± 0.8 mEq 1−1 and [CL−] = 122 ± 3.0 mEq 1−1. Freshwater acclimated sturgeon had an osmolality of 236 ± 7, [Na+] = 131.6 + 4.4, [K+] = 2.5 ± 0.7 and [CL−] = 110.6 ± 3.6. Freshwater acclimated fish gradually exposed to sea water (increase of 5 ppt h−1) had higher plasma osmolalities than did the bay water acclimated fish. These young adult sturgeon are able to tolerate transfer
from fresh water to sea water as well as gradual transfer from sea water to fresh water. Plasma electrolytes in transferred
fish are regulated, but tend to differ from long term acclimated fish at the same salinities. There is a gradual increase
in the upper salinity tolerance (abrupt transfer) of juvenile white sturgeon with weight: 5–10 ppt for 0.4–0.9 g fish, 10–15
ppt for 0.7–1.8 g fish, and 15 ppt for 4.9–50.0 g fish. The ability of juveniles to regulate plasma osmolality is limited.
The young adult fish are able to tolerate higher salinities (35 ppt) than juvenile sturgeon but probably are also characterized
by low activity of the necessary ion exchange mechanisms in the gills which permit rapid adjustment of blood electrolytes
with graduate change in external salinity. 相似文献
11.
Nicholas A. Burd Daniel W. D. West Aaron W. Staples Philip J. Atherton Jeff M. Baker Daniel R. Moore Andrew M. Holwerda Gianni Parise Michael J. Rennie Steven K. Baker Stuart M. Phillips 《PloS one》2010,5(8)
Background
We aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.Methodology/Principal Findings
Fifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.Conclusions/Significance
These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes. 相似文献12.
The effects of temperature (20, 24 and 28 °C) and irradiance (15 and 40 μmol photon m−2 s−1) on the nitrate and ammonium uptake rates of the subtropical red alga, Laurencia brongniartii, were investigated to prepare for tank cultivation. Nitrate uptake followed saturation kinetics and was faster at higher
irradiances and temperatures. In contrast, ammonium uptake was linear over the experimental range and was not affected by
an increase in temperature. A parameter, β, was calculated to compare substrate uptake rates of nitrate along the linear portion
of the uptake curve with that of ammonium. For nitrate, β was lower at low irradiance and higher at high irradiance (β = 0.007
± 0.003 and 0.030 ± 0.002 [μmol N L−1 (μmol N gww−1 d−)−1], respectively). However, β was 0.023 ± 0.002 and 0.034 ± 0.002 [μmol N L−1 (μmol N gww−1 d−1)−1] for ammonium, suggesting a preference for ammonium over nitrate. 相似文献
13.
Ioannis G. Fatouros Allan H. Goldfarb Athanasios Z. Jamurtas Theodore J. Angelopoulos Jiaping Gao 《European journal of applied physiology and occupational physiology》1997,76(3):203-208
β-Endorphin (BE) infusion at rest can influence insulin and glucagon levels and thus may affect glucose availability during
exercise. To clarify the effect of BE on levels of insulin, glucagon and glucose during exercise, 72 untrained male Sprague-Dawley
rats were infused i.v. with either: (1) BE (bolus 0.05 mg · kg−1 +0.05 mg · kg−1 · h−1, n = 24); (2) naloxone (N, bolus 0.8 mg · kg−1 + 0.4 mg · kg−1, n = 24); or (3) volume-matched saline (S, n = 24). Six rats from each group were killed after 0, 60, 90 or 120 min of running at 22 m · min−1, at 0% gradient. BE infusion resulted in higher plasma glucose levels at 60 min [5.93 (0.32) mM] and 90 min [4.16 (0.29) mM]
of exercise compared to S [4.62 (0.27) and 3.41 (0.26 mM] and N [4.97 (0.38) and 3.44 (0.25) mM]. Insulin levels decreased
to a greater extent with BE [21.5 (0.9) and 18.3 (0.6) uIU · ml−1] at 60 and 90 min compared to S [24.5 (0.5) and 20.6 (0.6) uIU · ml−1] and N [24.5 (0.4) and 21.6 (0.7) uIU · ml−1] groups. Plasma C-peptide declined to a greater extent at 60 and 90 min of exercise with BE infusion compared to both S and
N. BE infusion increased glucagon at all times during exercise compared to S and N. These data suggest that BE infusion during
exercise influences plasma glucose by augmenting glucagon levels and attenuating insulin release.
Accepted: 26 February 1997 相似文献
14.
Theodore J. Angelopoulos Rebecca Lewis Thanassis Jamurtas Chris Schumann 《European journal of applied physiology and occupational physiology》1998,77(6):556-559
We characterized the effect of ten days of training on lipid metabolism in 6 [age 37.2 (2.3) years] sedentary, obese [BMI
34.4 (3.0) kg · m−2] males with normal glucose tolerance. An oral glucose tolerance test was performed prior to and at the end of the 10 d of
training period. The duration of each daily exercise session was 40 min at an intensity equivalent to ˜75% of the age predicted
maximum heart rate. Blood measurements were performed after an overnight fast, before and at the end of the 10 d period. Plasma
triacylglycerol was significantly (p < 0.05) reduced following exercise training (2.15 ± 0.29 vs. 1.55 ± 0.28 mmol · l−1). Very low density lipoprotein-triacylglycerol was also significantly (p < 0.05) reduced (1.82 ± 0.3 vs. 1.29 ± 0.29 mmol · l−1). No significant changes in high density lipoprotein-cholesterol were observed as a result of training. Following training
fasting plasma glucose and fasting plasma insulin were significantly reduced [Glucose: 5.9 (0.2) mmol · l−1 vs. 5.3 (0.22) mmol · l−1 (p < 0.05); Insulin 264.3 (53.8) ρ · mol · l−1 vs. 200.9 (30.1) ρ · mol · l−1, p = 0.05]. The total area under the glucose curve during the OGTT decreased significantly (p < 0.05). These preliminary data suggest that short-term exercise, without concomitant loss of body mass, induces favorable
changes in plasma triacylglycerol, and very low density lipoprotein-triacylglycerol and glucose tolerance but has no effect
on high density lipoproteincholesterol.
Accepted: 7 January 1998 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.
Thomas Rohde Sven Asp Dave A. MacLean Bente K. Pedersen 《European journal of applied physiology and occupational physiology》1998,78(5):448-453
This study examined whether oral glutamine supplementation abolishes some of the exercise-induced changes in lymphocyte functions
following long-term intense exercise. A group of 16 marathon runners participating in The Copenhagen Marathon 1996 were placed
randomly in either a placebo (n = 7) or a glutamine receiving group (n = 9). Each subject received four doses of either placebo or glutamine (100 mg · kg−1) administered at 0, 30, 60, and 90-min post-race. In the placebo group the plasma glutamine concentrations were lower than
pre-race values during the post-exercise period [mean 647 (SEM 32) compared to 470 (SEM 22) μmol · l−1 90-min post-race, P < 0.05] whereas glutamine supplementation maintained the plasma glutamine concentration (at ∼750 μmol · l−1). Glutamine supplementation in vivo had no effect on the lymphokine activated killer (LAK) cell activity, the proliferative
responses or the exercise-induced changes in concentrations or percentages of any of the leucocyte subpopulations examined.
Glutamine addition in in vitro studies enhanced the proliferative response in both groups. These data would suggest that decreased
plasma glutamine concentrations post-exercise are not responsible for exercise-induced decrease in LAK activity and that the
influence of glutamine in vitro is not dependent on the plasma glutamine concentration at the time of sampling.
Accepted: 23 April 1998 相似文献
17.
Plasma lactate, GH and GH-binding protein levels in exercise following BCAA supplementation in athletes 总被引:4,自引:0,他引:4
Summary. Branched chain amino acids (BCAA) stimulate protein synthesis, and growth hormone (GH) is a mediator in this process. A pre-exercise
BCAA ingestion increases muscle BCAA uptake and use. Therefore after one month of chronic BCAA treatment (0.2 g kg−1 of body weight), the effects of a pre-exercise oral supplementation of BCAA (9.64 g) on the plasma lactate (La) were examined
in triathletes, before and after 60 min of physical exercise (75% of VO2max). The plasma levels of GH (pGH) and of growth hormone binding protein (pGHBP) were also studied. The end-exercise La of
each athlete was higher than basal. Furthermore, after the chronic BCAA treatment, these end-exercise levels were lower than
before this treatment (8.6 ± 0.8 mmol L−1 after vs 12.8 ± 1.0 mmol L−1 before treatment; p < 0.05 [mean ± std. err.]). The end-exercise pGH of each athlete was higher than basal (p < 0.05). Furthermore,
after the chronic treatment, this end-exercise pGH was higher (but not significantly, p = 0.08) than before this treatment
(12.2 ± 2.0 ng mL−1 before vs 33.8 ± 13.6 ng mL−1 after treatment). The end-exercise pGHBP was higher than basal (p < 0.05); and after the BCAA chronic treatment, this end-exercise
pGHBP was 738 ± 85 pmol L−1 before vs 1691 ± 555 pmol L−1 after. pGH/pGHBP ratio was unchanged in each athlete and between the groups, but a tendency to increase was observed at end-exercise.
The lower La at the end of an intense muscular exercise may reflect an improvement of BCAA use, due to the BCAA chronic treatment.
The chronic BCAA effects on pGH and pGHBP might suggest an improvement of muscle activity through protein synthesis.
Received January 5, 1999 / Accepted June 17, 1999 相似文献
18.
M.-T. Linossier D. Dormois P. Brégère A. Geyssant C. Denis 《European journal of applied physiology and occupational physiology》1997,76(1):48-54
The aim of this study was to examine whether the alkalosis-induced improvement in supramaximal performance could be explained
by a less-altered muscle metabolic status. Eight subjects first performed exhausting exercise at 120% peak oxygen uptake after
ingesting either a placebo (PLC) or sodium citrate (CIT) at a dose of 0.5 g · kg−1 body mass to determine exhaustion time (t
exh). They then, performed exercise (Lim-EX) at the same relative intensity lasting PLCt
exh minus 20 s in both treatments. Samples were taken from vastus lateralis muscle at rest (90-min after the ingestion) and at
the end of Lim-EX. Arterial blood samples were obtained at rest (immediately prior to and 90 min after ingesting the drug)
and during the 20-min post-exercise recovery. The t
exh was significantly increased by CIT [PLC 258 (SD 29) s, CIT 297 (SD 45) s]. The CIT raised the rest [citrate] in blood [PLC
0.11 (SD 0.01) mmol · l−1, CIT 0.34 (SD 0.07) mmol · l−1] and in muscle [PLC 0.78 (SD 0.23) mmol · kg−1 dry mass, CIT 1.00 (SD 0.21) mmol · kg−1 dry mass]. Resting muscle pH and buffering capacity were unchanged by CIT. The same fall in muscle pH was observed during
Lim-EX in the two conditions. This was associated with similar variations in both the cardio-respiratory response and muscle
energy and metabolism status in spite of a better blood acid-base status after CIT. Thus, CIT would not seem to allow the
alkalinization of the muscle cytosolic compartment. Though sodium citrate works in a similar way to NaHCO3 on plasma alkalinization and exercise performance, the exact nature of the mechanisms involved in the delay of exhaustion
could be different and remains to be elucidated.
Accepted: 26 November 1996 相似文献
19.
Antarctic marine organisms are considered to have extremely limited ability to respond to environmental temperature change.
However, here we show that the Antarctic notothenioid fish Pagothenia borchgrevinki is an exception to this theory. P. borchgrevinki was able to acclimate its resting metabolic rate and resting ventilation frequency after a 5°C rise in temperature. Acute
exposure to 4°C resulted in an elevation in metabolic rate (57.8 ± 4.79 mg O2 kg−1 h−1) and resting ventilation rate (40.38 ± 1.61 breaths min−1) compared with fish at −1°C (metabolic rate 34.45 ± 3.12 mg O2 kg−1 h−1; ventilation rate 29.88 ± 3.72 breaths min−1). However, after a 1-month acclimation period, there was no significant difference in the metabolic rate (cold fish 29.52 ± 3.01;
warm fish 31.13 ± 2.30 mg O2 kg−1 h−1), or the resting ventilation rate (cold fish 28.75 ± 0.98; warm fish 34.25 ± 2.28 breaths min−1) of cold and warm acclimated fish. Acclimation changes to the rate of oxygen consumption following exhaustive exercise were
complex. The pattern of oxygen consumption during recovery from exhaustive exercise was not significantly different in either
cold or warm acclimated fish. 相似文献
20.
Hiroshi Takashima Ayako Araki Keiko Takemoto Naokazu Yoshikawa Keiichi Tsukahara 《Journal of biological inorganic chemistry》2006,11(3):316-324
In order to understand the detailed mechanism of the stereoselective photoinduced electron-transfer (ET) reactions of zinc-substituted
myoglobin (ZnMb) with optically active molecules by flash photolysis, we designed and prepared new optically active agents,
such as N,N′-dimethylcinchoninium diiodide ([MCN]I2) and N,N′-dimethylcinchonidinium diiodide ([MCD]I2). The photoexcited triplet state of ZnMb, 3(ZnMb)*, was successfully quenched by [MCN]2+ and [MCD]2+ ions to form the radical pair of ZnMb cation (ZnMb·+) and reduced [MCN]·+ and [MCD]·+, followed by a thermal back ET reaction to the ground state. The rate constants (k
q) for the ET quenching at 25 °C were obtained as k
q(MCN)=(1.9±0.1)×106 M−1 s−1 and k
q(MCD)=(3.0±0.2)×106 M−1 s−1, respectively. The ratio of k
q(MCD)/k
q(MCN)=1.6 indicates that the [MCD]2+ preferentially quenches 3(ZnMb)*. The second-order rate constants (k
b) for the thermal back ET reaction from [MCN]·+ and [MCD]·+ to ZnMb·+ at 25 °C were k
b(MCN)=(0.79±0.04)×108 M−1 s−1 and k
b(MCD)=(1.0±0.1)×108 M−1 s−1, respectively, and the selectivity was k
q(MCD)/k
q(MCN)=1.3. Both quenching and thermal back ET reactions are controlled by the ET step. In the quenching reaction, the energy
differences of ΔΔH
≠(MCD–MCN) and ΔΔS
≠(MCD–MCN) at 25 °C were obtained as −1.1 and 0 kJ mol−1, respectively. On the other hand, ΔΔH
≠(MCD–MCN)=11±2 kJ mol−1 and TΔΔS
≠(MCD–MCN)=−10±2 kJ mol−1 were given in the thermal back ET reaction. The highest stereoselectivity of 1.7 for [MCD]·+ found at low temperature (10 °C) was due to the ΔΔS
≠ value obtained in the thermal back ET reaction.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献