ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Acute compartment syndromes usually occur as a complication of major trauma. While the chronic exertional anterior tibial compartment syndrome is well described in the sports medicine literature, reports of acute tibial compartment syndromes due to physical exertion, or repetitive microtrauma, are rare. The case of an adolescent female who developed an acute anterior compartment syndrome from running in a soccer game is described in this report. Failure to recognize the onset of an acute exertional compartment syndrome may lead to treatment delay and serious complications. Whereas the chronic exertional anterior compartment syndrome is characterized by pain that diminishes with the cessation of exercise, the onset of the acute exertional anterior compartment syndrome is heralded by pain that continues, or increases, after exercise has stopped. Compartment pressure measurement confirms the clinical diagnosis and helps guide treatment. True compartment syndromes require urgent fasciotomy.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The purpose of this study was to identify the effects of knee immobilization on uninvolved lower extremity joints during gait. Video and force platform data were collected for seven subjects walking normally (N) and with the knee fixed at three flexion angles: 0° (BOO), 10° (B10), and 20° (B20). A bilateral, sagittal plane link-segment model was used to determine lower limb kinematic and kinetic measures. Mean data from three normal and five braced gait trials were compared using one-way repeated measures ANOVA (P < 0.05). Significant increases in involved limb (IL) ankle generation work (J·kg−1) during propulsion were evident: (N = 0.249, BOO = 0.295, B1O = 0.293, B20 = 0.308). There were significant increases in peak IL hip power (W·kg−1) in early stance (N = 0.638, BOO = 1.056, B10 = 1.018, B20 = 1.097) and in IL hip absorption work (J·kg−1) during late stance (N = 0.049, BOO = 0.080, B10 = 0.082, B20 = 0.079). The hip of the uninvolved limb (UL) displayed significant increases in generation work (J·kg−1) in early stance (N = 0.089, BOO = 0.183, B10 = 0.149, B20 = 0.179). Normal kinematic and kinetic-patterns of other joints were changed with knee immobilization. The major effects were increases in the magnitude of IL peak hip and ankle joint kinetic measures. Fixing the knee in 10° of flexion resulted in the fewest significant changes in normal gait mechanics.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Although in able-bodied individuals heart rate (HR) indicates exercise intensity, the linearity of the HR/oxygen uptake (VO2) relationship has not been established in persons with quadriplegia with impaired sympathetic function. The HR/VO2relationship and four ACSM recommended methods of exercise prescription were evaluated in 11 individuals with quadriplegia during intermittent progressive peak exercise tests. Tests were conducted in either a supine or sitting position using an arm ergometer. The HR response was highly variable, with HR/VO2correlation coefficients ranging from 0.22 to 0.99. A 2 X 2 ANOVA revealed an interaction between injury level, high-level (above C7) vs low-level (C7 and below) and exercise position, with the high-level group exhibiting the lower coefficient (0.68) between the HR/VO2relationship in the sitting position. For all subjects, the target of 55–90% peak HR (mean = 72.5%) corresponded to 34% peak power output (PO) in sitting and 44% peak PO in supine. Similarly, 70% peak VO2corresponded to 46% and 50% of peak PO (sitting and supine, respectively). A rating of perceived exertion (RPE) of 10–12 corresponded to 50–60% peak PO and was associated with a higher PO than that predicted by the HR or VO2methods. The results of this study indicate that exercise intensity for quadriplegics be based on 50–60% peak PO and/or an RPE of 10–12.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

To examine the effects of exercise on plasma lipids and metabolism during lactation, sedentary, exclusively breast-feeding women were randomly assigned to an exercise (E) or control (C) group at 6–8 wk postpartum. E subjects performed aerobic exercise 45 min·d−1, 5 d·wk−1, for 12 wk. Resting metabolic rate (RMR), energy expenditure, body composition, and dietary intake were measured at 6–8, 12–14, and 18–20 wk postpartum. Maximum oxygen uptake (VO2max), postprandial insulin, glucose, and thermic response, and plasma lipid levels were measured at 6–8 and 18–20 wk. VO2maxincreased by 25% vs 5% in the E vs the C group, respectively (P< 0.0001). RMR was similar between groups and did not change over time. Weight and percent body fat declined (P< 0.01) during the study, but there was no difference between E and C groups. Exercise marginally-increased high-density lipoprotein cholesterol levels (P< 0.08), but did not affect other lipid concentrations. Insulin response decreased as VO2maxincreased (P= 0.05). There was no effect of time or group on glucose or thermic response. Exercise improves cardiovascular fitness during lactation, but does not increase the rate of postpartum weight loss.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

To study the influence of gender on peak oxygen uptake and on the hemodynamic response to dynamic exercise in essential hypertension, 45 male and 45 female patients, matched for age and blood pressure, were studied. Blood pressure was measured intra-arterially and cardiac output by the direct oxygen Fick method. Anthropometric gender differences were accounted for by statistical adjustment for height and weight. The increase of absolute and adjusted stroke volume from sitting at rest to submaximal (50 W) and to peak bicycle exercise was smaller in women, than in men (P< 0.05). At 50 W, oxygen uptake (0.96 vs 0.97 1·min−1) and cardiac output (10.9 vs 11.2 1·min−1) were not different between women and men, due to the sleeper exercise-induced rises of heart rate (P< 0.001) and arteriovenous oxygen difference (P< 0.05) in the women. Women reached the same peak heart rate as men (168 vs 173 b·min−1), so that the lower (P< 0.001) stroke volume (77 vs 99 ml) and cardiac output (12.9 vs 17.0 1·min−1), together with the lower hemoglobin-concentration, contributed to their impaired peak oxygen uptake (P< 0.001), both before (1.35 vs 2.17 1·min−1) and after adjustment for body size (1.44 vs 2.07 1·min−1). In conclusion, at fixed submaximal exercise, women achieve the same oxygen uptake and cardiac output as men despite a lower stroke volume, through adaptations of heart rate and peripheral oxygen extraction; their peak aerobic power and cardiac output are, however, substantially lower than in men.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The role of O2delivery in regulating &OV0312;O2maxhas been studied in an isolated gastrocnemius-plantaris muscle preparation contractingin situ; recent data addressing this issue are presented. &OV0312;O2increases nonlinearly with stimulation frequency reaching a peak at 5 twitches·s−1or 1 tet·s−1(200 ms trains, 50 imp·s−1). Further increases in stimulation frequency result in a lower &OV0312;O2. Measured &OV0312;O2maxima are less than predicted &OV0312;O2capacity, and peak &OV0312;O2during tetanic contractions is greater than that during twitches. Above 150 imp·min−1, &OV0312;O2is directly related to the level of blood flow attained as &OV0312;O2/&OV0422; (arterial-venous O2difference) is fixed by some unknown mechanism. Increasing blood flow, with a pump, during 1·s−1tetanic contractions increases O2diffusive conductance and peak &OV0312;O2. When O2delivery is reduced, ischemic hypoxia appears to result in more rapid reductions in muscle performance than hypoxic hypoxia because of decreases in perfusion pressure and &OV0422;.31P-NMR studies reveal that reductions in creatine phosphate and energy charge are similar between ischemia and hypoxia suggesting a common regulator, O2. We conclude that &OV0312;O2maxis limited by O2delivery as a result of a limited and uneven distribution of muscle blood flow. These limitations appear secondary to mechanical restraints imposed by contraction duty cycle and vascular compression.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

During repetitive contractions, the VO2of the dog gastrocnemius-plantaris muscle rose with the contraction frequency up to a maximal value and then decreased as contraction frequency was increased further. PVO2was constant over most of the contraction frequency range. Reducing perfusion pressure/blood flow reduced &OV0312;O2max), with a constant PVO2. During these maneuvers the diffusion conductance, DCO2(&OV0312;O2/PVO2), changed with &OV0312;O2. Raising the perfusion pressure/flow with a pump increased &OV0312;O2with a small rise in PVO2so that DCO2also increased. Removing tension from the muscle-between contractions elevated &OV0312;O2and DCO2without a change in perfusion pressure. Hypoxemia decreased &OV0312;O2with a decrease in PVO2,; DCO2remained constant. A three-compartment mathematical model, based on microsphere measurements of regional flow, was used to illustrate how regional flow variations may exist, and how they are poorly revealed in the mixed whole-muscle venous blood. The model shows &OV0312;O2·g−1strongly related to flow. As &OV0312;O2·−1increased as &OV0422;·g−1Increased, extraction decreased; and DCO2increased.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Whether maximal oxygen uptake (&OV0312;O2max) during exercise in healthy subjects reflects limitation of the supply of oxygen to muscle mitochondria or an inability to use oxygen beyond some biochemical limit remains debated. This paper summarizes evidence for the hypothesis that &OV0312;O2maxis limited by O2supply. How the many steps in the pathway for oxygen interact to determine maximum oxygen supply is analyzed, resulting in a mathematical model of predictive value. A major component of this model is the diffusional transport of oxygen out of the muscle microcirculation. The proportionality between &OV0312;O2maxand the capillary to mitochondrion partial pressure gradient (as FIO2is altered) supports this hypothesis, but does not exclude the existence of convective heterogeneity of blood flow as a factor contributing to the limitation of &OV0312;O2max. Although there is no direct method for measuring convective heterogeneity, altering hemoglobin P50permits distinguishing diffusive from convective elements in limiting &OV0312;O2max, and both the underlying theory and the results are summarized herein. Our conclusion is that &OV0312;O2maxin health appears limited by the supply of oxygen to the mitochondria, which in turn, depends upon the integrated interaction among all of the diffusive and convective steps in the oxygen pathway between the environment and the mitochondria.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID