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排序方式: 共有203条查询结果,搜索用时 265 毫秒
31.
Geertje A. M. Ari?ns Willem van Mechelen Han C. G. Kemper Jos W. R. Twisk Willem van Mechelen 《European journal of applied physiology and occupational physiology》1997,76(3):214-220
The purpose of this study was to describe the longitudinal development of running economy [defined as the oxygen uptake (V˙O2) at a submaximal running speed] in males and females from teenage to young adult age using data from the Amsterdam Growth
and Health Study. Submaximal V˙O2 (in ml · kg−1· min−1) was measured in 84 males and 98 females while they ran on a treadmill at a constant speed of 8 km · h−1 for 6 min at three different treadmill slopes (0%, 2.5% and 5%). This test was carried out six times, on the same subjects
at the ages of 13, 14, 15, 16, 21, and 27 years. The longitudinal development of running economy in males and females was
analysed using a two-way analysis of variance for repeated measurements. At all three slopes, a significant decrease in V˙O2 with increasing age was found for both males and females, implying a significant increase in running economy for both sexes.
Males showed significantly higher V˙O2 values than females at all ages measured and for all three slopes, suggesting that females have a significantly higher running
economy than males. In order to make a better comparison of the V˙O2 of individuals of different sizes, allometric models were used; power function ratios were constructed in which body mass
was expressed to an exponential power. Following this analysis the difference in submaximal V˙O2 and running economy between males and females appeared even larger.
Accepted: 20 February 1997 相似文献
32.
Gerald S. Zavorsky David L. Montgomery David J. Pearsall 《European journal of applied physiology and occupational physiology》1998,77(3):224-230
The purposes of this study were to determine whether running economy (RE) is adversely affected following intense interval
bouts of 10 × 400-m running, and whether there is an interaction effect between RE and recovery duration during the workouts.
Twelve highly trained male endurance athletes [maximal oxygen consumption; V˙O2
max
=72.5 (4.3) ml·kg−1·min−1; mean (SD)] performed three interval running workouts of 10 × 400 m with a minimum of 4 days between runs. Recovery duration
between the repetitions was randomly assigned at 60, 120 or 180 s. The velocity for each 400-m run was determined from a treadmill
V˙O2
max
test. The average running velocity was 357.9 (9.0) m · min−1. Following the workout, the rating of perceived exertion (RPE) increased significantly (P < 0.01) as recovery duration between the 400-m repetitions decreased (14.4, 16.1, and 17.7 at 180s, 120s, and 60 s recovery,
respectively). Prior to and following each workout, RE was measured at speeds of 200 and 268 m · min−1. Changes in RE from pre- to post-workout, as well as heart rate (HR) and respiratory exchange ratio (R) were similar for the three recovery conditions. When averaged across conditions, oxygen consumption (V˙O2) increased significantly (P < 0.01) from pre- to post-test (from 38.5 to 40.5 ml · kg−1 · min−1 at 200 m · min−1, and from 53.1 to 54.5 ml · kg−1 · min−1 at 268 m · min−1, respectively). HR increased (from 124 to 138, and from 151 to 157 beats · min−1 respectively) and R decreased (from 0.90 to 0.78, and from 0.93 to 0.89, respectively) at 200 and 268 m · min−1, respectively (P < 0.01). This study showed that RE can be perturbed after a high-intensity interval workout and that the changes in V˙O2, HR and R were independent of the recovery duration between the repetitions.
Accepted: 23 June 1997 相似文献
33.
Fifteen young adult Singaporean male physical education students maximum oxygen consumption [(V˙O2max) = 56 (4.7) ml · kg−1 · min−1] performed three prolonged runs in a counterbalanced design. The running bouts varied in time (40 vs 60 min) and intensity
(70% vs 80% V˙O2
max
). Each prolonged run was separated by 7 days. The running economy (RE) at 10.8 km · h−1 during 10-min running bouts was measured before (RE1) and after (RE2) each prolonged run. A control study involved monitoring
RE at 10.8 km · h−1 before and after 60 min rest. There were no differences between RE1 and RE2 values during the control run. However, there
were differences between RE1 and RE2 values when separated by a prolonged run. For example, the mean (SD) changes in oxygen
consumption (ml · kg−1 · min−1) values were 38.2 (2.5) versus 40.1 (2.6) (40 min at 80% V˙O2
max
), 38.9 (2.8) versus 41.5 (2.6) (60 min at 70% V˙O2
max
), and 39.0 (3.1) versus 42.7 (2.9) (60 min at 80% V˙O2
max
; P < 0.01). The results of this investigation support the hypothesis that RE deteriorates during prolonged running, and that
the magnitude of the deterioration in RE increases with both increasing exercise intensity and duration.
Accepted: 14 July 1997 相似文献
34.
Josephine T. Tauer Gustavo Henrique Rigo Canevazzi Justine Schiettekatte-Maltais Frank Rauch Raynald Bergeron Louis-Nicolas Veilleux 《Journal of musculoskeletal & neuronal interactions》2021,21(4):517
Objective:The objective of the current study is to assess the effect of a seven-week voluntary wheel running intervention on muscles and bones properties in a mouse model mimicking dominant severe osteogenesis imperfecta (OI).Methods:Female wild-type (WT) and OI (Col1a1Jrt/+) mice either performed voluntarily wheel-running exercise for 7-weeks or remained sedentary. Running distance and speed, forelimb grip strength, isolated muscle force and fatigability as well as bone morphology and mechanical properties were assessed.Results:We demonstrate that female WT and OI mice voluntarily performed exercise, although OI mice exercised less than WT littermates. The exercise regimen increased soleus muscle masses in WT and OI but increased relative grip strength in WT mice only. Specific muscle force and fatigability were similar between WT and OI mice and did not improve with exercise. Furthermore, the exercise regimen did not improve the femoral architectural and biomechanical properties in OI mice.Conclusion:Our study suggests that voluntary wheel running is not appropriate to assess the effects of exercise in a mouse model of OI. Findings from exercising OI mice model studies may not necessarily be transferable to humans. 相似文献
35.
36.
Two novel bolaamphiphile based dicarboxylic ligands L1H2 and L2H2 are synthesized by desymmetrizing aromatic anhydrides. The corresponding Cu(II) complexes [Cu(L1) · EtOH]2 (1), [Cu(L2) · (CH3CN)]2 (2) are synthesized and characterized. The crystal structure obtained for (1) and (2) indicates that they are new class of tetralactone type macrocyclic Cu(II) chelate complexes with paddle wheel Cu2-acetate cage structure. The 1:1, Cu(II) and ligand ratio leads into formation of a novel binuclear Cu(II) tetracarboxylate complexes. The macrocyclic chelate ring size in compounds 1 and 2 was altered from [15] membered to [19] membered by introducing phthalyl and diphenyl head groups as discussed in detail. The single crystal X-ray structure shows the Cu(II)?Cu(II) distance 2.613(13) Å for 1 and 2.626(13) Å for 2, the corresponding room temperature EPR spectra recorded for powdered polycrystalline samples indicate the existence of Cu(II)?Cu(II) dimeric system. 相似文献
37.
Electromyograms of different muscles can be submitted to a wavelet-transform and arranged in a Multi-Muscle Pattern (MMP). The MMP represents the intensity of the EMG signals of a number of muscles simultaneously in time/frequency space. As previously shown, the MMPs can be represented by points in an Euclidian vector space that was called pattern space. The variability of the MMPs is represented by the distribution of the scattered points in pattern space. The purpose of this study was to investigate the distribution of the points and use the properties of the distribution to classify MMPs. The first task was to test whether the points representing a group of MMPs were located between the inner and outer boundary of a sphere-like domain in whitened pattern space as theoretically predicted. The mean of these points and thus of the MMPs is represented by a point at the center of the sphere. The hypothesis was that the spheres representing points of the MMPs of barefoot and shod runners were sufficiently separated and distinguishable in pattern space to allow classification of the runners according to their shod condition. The results confirmed the hypothesis and revealed that the recognition rate was over 80%. One can conclude and generalize that the points representing MMPs recorded for a certain condition reside between the inner and outer boundary of the sphere. The classification based on the spherical feature represents a much better discrimination than one based on the distance from the mean. 相似文献
38.
T. H. Meek J. C. Eisenmann B. K. Keeney R. M. Hannon E. M. Dlugosz T. Garland Jr 《Genes, Brain & Behavior》2014,13(3):322-332
Experimental studies manipulating diet and exercise have shown varying effects on metabolic syndrome components in both humans and rodents. To examine the potential interactive effects of diet, exercise and genetic background, we studied mice from four replicate lines bred (52 generations) for high voluntary wheel running (HR lines) and four unselected control lines (C). At weaning, animals were housed for 60 days with or without wheels and fed either a standard chow or Western diet (WD, 42% kcal from fat). Four serial (three juvenile and one adult) blood samples were taken to measure fasting total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C), triglycerides and glucose. Western diet was obesogenic for all mice, even after accounting for the amount of wheel running and kilojoules consumed. Western diet significantly raised glucose as well as TC and HDL‐C concentrations. At the level of individual variation (repeatability), there was a modest correlation (r = 0.3–0.5) of blood lipids over time, which was reduced with wheel access and/or WD. Neither genetic selection history nor wheel access had a statistically significant effect on blood lipids. However, HR and C mice had divergent ontogenetic trajectories for body mass and caloric intake. HR mice also had lower adiposity, an effect that was dependent on wheel access. The environmental factors of diet and wheel access had pronounced effects on body mass, food consumption and fasting glucose concentrations, interacting with each other and/or with genetic strain. These data underscore the importance (and often unpredictable nature) of genotype‐by‐environment and environment‐by‐environment interactions when studying body weight regulation. 相似文献
39.
Variables during swing associated with decreased impact peak and loading rate in running 总被引:1,自引:0,他引:1
When the foot impacts the ground in running, large forces and loading rates can arise that may contribute to the development of overuse injuries. Investigating which biomechanical factors contribute to these impact loads and loading rates in running could assist clinicians in developing strategies to reduce these loads. Therefore, the goals of our work were to determine variables that predict the magnitude of the impact peak and loading rate during running, as well as to investigate how modulation of knee and hip muscle activity affects these variables. Instrumented gait analysis was conducted on 48 healthy subjects running at 3.3 m/s on a treadmill. The top four predictors of loading rate and impact peak were determined using a stepwise multiple linear regression model. Forward dynamics was performed using a whole body musculoskeletal model to determine how increased muscle activity of the knee flexors, knee extensors, hip flexors, and hip extensors during swing altered the predictors of loading rate and impact peak. A smaller impact peak was associated with a larger downward acceleration of the foot, a higher positioned foot, and a decreased downward velocity of the shank at mid-swing while a lower loading rate was associated with a higher positioned thigh at mid-swing. Our results suggest that an alternative to forefoot striking may be increased hip flexor activity during swing to alter these mid-swing kinematics and ultimately decrease the leg's velocity at landing. The decreased velocity would decrease the downward momentum of the leg and hence require a smaller force at impact. 相似文献
40.
R. Candau A. Belli G. Y. Millet D. Georges B. Barbier J. D. Rouillon 《European journal of applied physiology and occupational physiology》1998,77(6):479-485
The aim of the present study was to examine the physiological and mechanical factors which may be concerned in the increase
in energy cost during running in a fatigued state. A group of 15 trained triathletes ran on a treadmill at velocities corresponding
to their personal records over 3000m [mean 4.53 (SD 0.28) m · s−1] until they felt exhausted. The energy cost of running (C
R) was quantified from the net O2 uptake and the elevation of blood lactate concentration. Gas exchange was measured over 1 min firstly during the 3rd–4th min
and secondly during the last minute of the run. Blood samples were collected before and after the completion of the run. Mechanical
changes of the centre of mass were quantified using a kinematic arm. A significant mean increase [6.9 (SD 3.5)%, P < 0.001] in C
R from a mean of 4.4 (SD 0.4) J · kg−1 · m−1 to a mean of 4.7 (SD 0.4) J · kg−1 · m−1 was observed. The increase in the O2 demand of the respiratory muscles estimated from the increase in ventilation accounted for a considerable proportion [mean
25.2 (SD 10.4)%] of the increase in CR. A mean increase [17.0 (SD 26.0)%, P < 0.05] in the mechanical cost (C
M) from a mean of 2.36 (SD 0.23) J · kg−1 · m−1 to a mean of 2.74 (SD 0.55) J · kg−1 · m−1 was also noted. A significant correlation was found between C
R and C
M in the non-fatigued state (r = 0.68, P < 0.01), but not in the fatigued state (r = 0.25, NS). Furthermore, no correlations were found between the changes (from non-fatigued to fatigued state) in C
R and the changes in C
M suggesting that the increase in C
R is not solely dependent on the external work done per unit of distance. Since step frequency decreased slightly in the fatigued
state, the internal work would have tended to decrease slightly which would not be compatible with an increase in C
R. A stepwise regressions showed that the changes in C
R were linked (r = 0.77, P < 0.01) to the changes in the variability of step frequency and in the variability of potential cost suggesting that a large
proportion of the increase in C
R was due to an increase in the step variability. The underlying mechanisms of the relationship between C
R and step variability remains unclear.
Accepted: 15 September 1997 相似文献