摘要:

GARDNER, A. W. Sex differences in claudication pain in subjects with peripheral arterial disease.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1695–1698, 2002.PurposesTo compare the claudication distances between men and women patients with peripheral arterial disease (PAD), and to determine whether sex differences in claudication pain persisted after controlling for potential confounders such as demographic, functional, and physiological measures.MethodsA total of 488 men and 72 women functionally limited by intermittent claudication were evaluated. Patients were characterized on PAD-specific measures consisting of ankle/brachial index (ABI) and treadmill claudication distances, physical function measures consisting of ambulatory function, monitored physical activity, balance, and strength, and demographic measures obtained during a medical history.ResultsInitial claudication distance (ICD) was 33% shorter (P= 0.024) in women than in men (126 ± 22 vs 189 ± 13 m; mean ± SEM), and absolute claudication distance (ACD) was 23% shorter (P= 0.022) in women (313 ± 43 vs 407 ± 18 m). These differences were present despite similar (P= 0.440) ABI values between women (0.63 ± 0.02) and men (0.62 ± 0.01). Peak oxygen uptake (P= 0.043) and self-perceived stair climbing ability (P= 0.020) were different between men and women, and were independently related to ICD (multiple R = 0.57,P< 0.001) and to ACD (multiple R = 0.71,P< 0.001). The sex differences in ICD (P= 0.524) and ACD (P= 0.722) were no longer present after controlling for peak oxygen uptake and self-perceived stair climbing ability.ConclusionShorter treadmill claudication distances in women with PAD were explained by their lower cardiopulmonary fitness and poorer self-perceived ability to climb stairs than compared with men. Therefore, women with intermittent claudication represent a subgroup of PAD patients who should receive high priority for exercise rehabilitation to improve physical function.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

GATES, P. E., I. G. CAMPBELL, and K. P. GEORGE. Absence of training-specific cardiac adaptation in paraplegic athletes.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1699–1704, 2002.PurposeThe distinctive nature of left ventricular (LV) adaptation reported in able-bodied endurance- and power-trained athletes probably reflects the different hemodynamic loading patterns that occur during acute exercise. The exercise-induced hemodynamic loads in spinal cord injured athletes are different to those in able-bodied counterparts (lower venous return and stroke volume, higher heart rate). We sought to test the hypothesis that wall thickness, but not chamber dimension, would be larger in endurance- and power-trained spinal cord injured athletes compared with sedentary spinal cord injured subjects.MethodsWe undertook resting two-dimensional, motion-mode, and Doppler examinations of 11 power-trained, 10 endurance-trained, and 5 sedentary spinal cord injured volunteers and compared structural and functional LV data by using ANOVA. LV structural data were also analyzed after being scaled to body mass (BM)0.33.ResultsThere were no statistically significant differences among groups for any of the LV structural or functional measurements. However, there was a trend for larger mean wall thickness (0.95 ± 0.12 vs 0.83 ± 0.10 cm) and left ventricular mass (193 ± 57 vs 164 ± 66 g) in athletes compared with sedentary individuals.ConclusionIt seems unlikely that endurance and power training elicits distinctive patterns of LV enlargement in spinal cord injured athletes. Small adaptations of the left ventricle may occur with athletic training in the spinal cord injured athlete. Research within this population is complicated by extreme heterogeneity in important physical, physiological, and athletic-related variables.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

REJESKI, W. J., C. G. FOY, L. R. BRAWLEY, P. H. BRUBAKER, B. C. FOCHT, J. L. NORRIS III, and M. L. SMITH. Older adults in cardiac rehabilitation: a new strategy for enhancing physical function.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1705–1713, 2002.Introduction/PurposeThis study contrasted the effect of a group-mediated cognitive-behavioral intervention (GMCB) versus traditional cardiac rehabilitation (CRP) upon changes in objective and self-reported physical function of older adults [mean (SD) age of 64.7 (7.5) yr] after 3 months of exercise therapy.MethodsThis randomized clinical trial enrolled 147 participants who were eligible for inclusion into cardiac rehabilitation. Baseline to 3-month changes in self-reported and performance related measures of physical function were assessed using a physical functioning questionnaire, a 6-min walk test, and measured MET levels.ResultsPairedt-tests revealed that participants made improvements in all measures across the first 3 months of the study, irrespective of group treatment (P< 0.001). General linear models including effects for baseline levels of physical function, treatment, and gender revealed that lower functioning men in the GMCB treatment made greater improvements than any other subgroup on the two performance outcomes: 6-min walk and measured MET levels (P< 0.01). Gender did not moderate change in self-reported level of physical function (P> 0.05); however, the lower functioning participants in the GMCB intervention experienced greater improvements in self-reported physical function than those in CRP (P< 0.05).ConclusionsExercise therapy is a valuable intervention for improving physical function of older adults with cardiovascular disease (CVD) and those at increased risk for CVD. Baseline level of physical function and gender are important variables to consider when studying the relationship between exercise therapy and improvements in physical function.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ELLIOTT, B., and M. KHANGURE. Disk degeneration and fast bowling in cricket: an intervention study.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1714–1718, 2002.PurposeThe purpose of this study was to identify the relationship between the incidence of lumber disk degeneration and bowling technique after 3 yr of educational intervention.MethodsTwo groups of cricketers from the Western Australian fast-bowling development squads acted as subjects in this longitudinal study. Group 1 comprised 24 fast bowlers, of mean age 13.4 yr at the commencement of the study. They attended at least three of the four yearly testing sessions between 1997 and 2000. A further 17 of mean age (in 1998) of 13.2 yr attended a minimum of two of three yearly testing sessions between 1998 and 2000, and comprised group 2. Players were filmed laterally and from above by two video cameras during each testing session. Specific technique variables that previously had been linked with an increased incidence of lumbar disk abnormalities were measured from the videos. Magnetic resonance imaging (MRI) scans of the lumbar disks of each player were also recorded at approximately the same time. A yearly half-day clinic and six small group coaching sessions spread over the season were held to assist the bowlers develop techniques that had been linked with a reduction in back injuries.ResultsData showed that small group coaching significantly reduced the level of shoulder alignment counter-rotation in young fast bowlers. The incidence and progression of lumbar disk degeneration were also significantly reduced in parallel with this decreased shoulder counter-rotation.ConclusionTechnique assessment and modifications through an educational process aimed at reducing mechanical features that have been linked to back injury decreased the incidence and/or progression of lumbar spine disk degeneration.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

CROWTHER, G. J., S. A. JUBRIAS, R. K. GRONKA, and K. E. CONLEY. A “functional biopsy” of muscle properties in sprinters and distance runners.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1719–1724, 2002.PurposeFast- and slow-twitch human muscle fibers exhibit large (two- to threefold) differences in metabolic enzyme activities and contractile economy. We asked whether comparable flux differences are evident in the muscles of athletes specializing in extremely different (i.e., sprint and long-distance) running events.MethodsWe took anin vivo“functional biopsy” of the ankle dorsiflexor muscles of 17 members of a university track team by using31P magnetic resonance spectroscopy. Ten sprinters (SPR) and seven distance runners (DIS) performed rapid isometric dorsiflexions against the resistance of a plastic foot holder. The contractile cost of exercise and glycolytic flux were calculated from changes in pH, [PCr], and [Pi] during ischemic exercise, and oxidative capacity was calculated from PCr recovery kinetics after aerobic exercise.ResultsContractile costs were 47% higher in SPR than in DIS, whereas oxidative capacities were 52% higher in DIS than in SPR. Surprisingly, glycolytic ATP production was similar in the two groups.ConclusionThe muscles of SPR and DIS exhibit clear differences in energetic properties, but these differences are smaller than the two- to three-fold variations seen in the properties of individual muscle fibers.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

NEARY, J. P., D. C. MCKENZIE, and Y. N. BHAMBHANI. Effects of short-term endurance training on muscle deoxygenation trends using NIRS.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1725–1732, 2002.PurposeThis study examined changes in cardiorespiratory responses and muscle deoxygenation trends to test the hypothesis that both central and peripheral adaptations would contribute to the improvements in &OV0312;O2maxand simulated cycling performance after short-term high-intensity training.MethodsEight male cyclists performed an incremental cycle ergometer test to voluntary exhaustion, and a simulated 20-km time trial (20TT) on wind-loaded rollers before and after training (60 min × 5 d·wk−1× 3 wk at 85–90% &OV0312;O2max). Near-infrared spectroscopy (NIRS) was used to evaluate the trend in vastus medialis hemoglobin/myoglobin deoxygenation (Hb/Mb-O2) during both tests pre- and post-training.ResultsTraining induced significant increases (P≤ 0.05) in maximal power output (367 ± 63 to 383 ± 60 W), &OV0312;O2max(4.39 ± 0.66 to 4.65 ± 0.57 L·min−1), and maximal O2pulse (22.7 ± 3.2 to 24.6 ± 2.8 mL O2·beat−1) during the incremental test, but maximal muscle deoxygenation was unchanged. 20TT performance was significantly faster (27:32 ± 1:43 to 25:46 ± 1:44 min:s;P≤ 0.05) after training without a significant increase (P> 0.05) in the &OV0312;O2(4.02 ± 0.52 to 4.04 ± 0.51), heart rate (176 ± 9 to 173 ± 8 beats·min−1) or O2pulse (22.4 ± 3.2 to 23.5 ± 2.8 mL O2·beat−1). However, mean muscle deoxygenation during the 20TT was significantly lower after training (−550 ± 292 to −707 ± 227 mV,P≤ 0.05), and maximal deoxygenation showed a trend toward significance (−807 ± 344 to −1009 ± 331 mV,P= 0.08), suggesting a greater release of oxygen from Hb/Mb-O2via the Bohr effect.ConclusionThe significant improvement in &OV0312;O2maxinduced by short-term endurance training in well-trained cyclists was due primarily to central adaptations, whereas the simulated 20TT performance was enhanced due to localized changes in muscle oxygenation.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

CROWTHER, G. J., and R. K. GRONKA. Fiber recruitment affects oxidative recovery measurements of human muscle in vivo.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1733–1737, 2002.PurposeFast-twitch and slow-twitch muscle fibers are known to have distinct metabolic properties. However, it has not been clearly established whether such heterogeneity within mixed-fiber muscles can influence measurements of energy metabolismin vivo. We therefore tested the hypothesis that differences in muscle fiber recruitment can cause differences in whole-muscle oxidative recovery from exercise.MethodsWe used31P magnetic resonance spectroscopy to measure oxidative ATP synthesis in the ankle dorsiflexor muscles of eight healthy volunteers under a variety of recruitment conditions. Oxidative ATP synthesis after isometric exercise was quantified as the rate constantkPCr, the reciprocal of the time constant of PCr recovery.ResultskPCrwas 37% higher after low-force ramp contractions (which primarily recruit slow-twitch fibers) than after ballistic contractions to the same peak force (which recruit both fast- and slow-twitch fibers).kPCrwas also 24% higher after low-force ramp contractions than after high-force ramp contractions, presumably reflecting the recruitment of fast-twitch fibers at high forces.ConclusionOur results indicate that the muscle fibers recruited first in voluntary contractions have a higher oxidative capacity than those recruited last. Such metabolic differences among fibers can confound whole-muscle measurements and thus need to be taken into account when studying voluntary exercise.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

WILLEMS, M. E. T., and W. T. STAUBER. Fatigue and recovery at long and short muscle lengths after eccentric training.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1738–1743, 2002.PurposeTo determine the effects of high-speed eccentric training of rat plantar flexor muscles on: 1) maximum (120 Hz) force at 90° ankle position; 2) fatigue (40 concentric muscle actions, ROM 50°) and recovery (6 concentric muscle actions) tested at short or long muscle lengths; and 3) low-frequency fatigue.MethodsTraining consisted of eccentric muscle actions from ankle positions of 140° to 40° (velocity ∼ 400°·s−1) followed by unresisted concentric muscle actions (5 × 10 repetitions, 5 d·wk−1for 6 wk). Fatigue was induced by concentric muscle actions with a rest of 12.5 s between muscle actions, and recovery consisted of equivalent concentric muscle actions performed every 5 min for 30 min. Low-frequency fatigue was measured 35 min after testing at 90° ankle position by using the ratio of isometric force produced by 20- and 100-Hz stimulation frequencies.ResultsEccentric training increased maximal isometric force per muscle weight by 22% whereas muscle weights were unchanged. In control muscles (C), isometric force immediately preceding each concentric muscle action decreased more at long lengths than at short lengths during the fatigue protocol; this length-dependent difference disappeared after 30 min of recovery. At short lengths, isometric force decreased less in trained muscles (T) (C: 78.4 ± 3.6%; T: 59.6 ± 4.4%) and recovered more during the following 30-min period (C: 84.7 ± 2.5%; T: 95.4 ± 2.8% of initial values). Changes in F20/F100 were smaller for trained muscles (C: 35.4 ± 2.0%; T: 22.0 ± 1.4%).ConclusionsHigh-speed eccentric training (5 d·wk−1for 6 wk) reduced fatigability and enhanced recovery mainly at long muscle lengths. It also reduced low-frequency fatigue, which may be attributed to alterations in intracellular calcium handling.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

SMITH, M. E., J. BALMER, D. A. COLEMAN, S. R. BIRD, and R. C. R. DAVISON. Method of lactate elevation does not affect the determination of the lactate minimum.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1744–1749, 2002.PurposeThe aim of the study was to examine the effects of different lactate elevation protocols on the determination of the lactate minimum (Lacmin) point.MethodsEight highly trained racing cyclists each completed four continuous ramp lactate minimum tests using the following blood lactate elevation protocols: 1) continuous ramp maximal aerobic power (RMPmax) assessment, 2) 30-s maximal sprint, 3) 40-s maximal sprint, and 4) two 20-s maximal sprints separated by a 1-min recovery. Each blood lactate elevation protocol was followed by a 5-min active recovery leading into a continuous ramp test commencing at a power of 60% of RMPmax, using a 6 W·min−1ramp rate, lasting 15 minResultsPeak [La]bvalues were significantly higher (P> 0.05) after the RMPmaxcompared with all other protocols and higher in the 40-s versus 30-s sprint. However, by the start of Lacminramp, [La]bafter the RMPmaxwas no longer higher than the 40-s sprint, but Lacmin[La]bwas similar for all protocols. This resulted in no differences in the total decline of [La]bmeasured as a percentage from the highest to the lowest value. At Lacminpoint, there were no significant differences in power (P> 0.05), but heart rate was higher in the RMPmaxversus 2 × 20 s and &OV0312;O2was significantly higher after the 40 s compared with the 2 × 20 s protocol.ConclusionThis study demonstrated that the determination of lactate minimum power in cycling is not dependent upon the lactate elevation protocol.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

BENALLAL, H., C. DENIS, F. PRIEUR, and T. BUSSO. Assessment of arterial gas pressures and cardiac output using a breathing lung model.Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1750–1756, 2002.PurposeThe aim of this investigation was to evaluate a breathing lung model to estimate arterial gas partial pressures and cardiac output at rest and during exercise.MethodsA mathematical model was used to describe variations in gas fractions, alveolar volume, and gas exchange in the pulmonary capillaries during the breathing cycle. Experimental data were obtained from 17 healthy subjects at rest and during exercise at 40, 50, 65, and 75% &OV0312;O2maxon a cycle ergometer. &OV0312;O2, &OV0312;CO2, and PET,CO2were monitored continuously with a MedGraphics CPX/D gas exchange system. Arterial gases were measured in brachial artery blood samples drawn simultaneously with gas exchange. Cardiac output was measured using the CO2rebreathing method corrected by the arterial blood sample data. The model parameters including cardiac output, end-expiratory alveolar volume, and mixed-venous gas contents were estimated by fitting model &OV0312;CO2to experimental values over 50 breaths.ResultsThe fit of model parameters gave arterial gas partial pressures not significantly different from measured data. Measured Pa,CO2and Pa,O2were significantly correlated with model outputs (R2= 0.991 for Pa,CO2and R2= 0.999 for Pa,O2;P< 0.0001). The cardiac output values estimated using the breathing lung model were significantly correlated with the values obtained with the corrected CO2rebreathing method (R2= 0.71;P< 0.0001). There was, however, a significant 2.3 L·min−1difference between these two methods.ConclusionResults obtained with the proposed method were in good agreement with measured arterial gas partial pressures. Despite a certain degree of bias, the promising results for cardiac output demonstrate the reliability of this method that should be now evaluated using a gold standard method.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID