摘要:

YOUNG, D. R., D. S. SHARP, and J. D. CURB. Associations among baseline physical activity and subsequent cardiovascular risk factors.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1646–1654, 1995. To determine stability of cross-sectional associations between physical activity and cardiovascular risk factors and provide information regarding possible independent effects of physical activity on reduced cardiovascular disease, this report examined associations among baseline physical activity and risk factors measured over 15 yr. Subjects were 1,379 Honolulu Heart Program participants who were evaluated at baseline and three subsequent examinations. For men initially 45–54 yr, higher physical activity level was significantly associated cross-sectionally and at 2 yr with lower diastolic blood pressure, body mass index, and skinfold thicknesses, and at 5 yr with higher high density lipoprotein (HDL) cholesterol. By the 15-yr examination, only associations between physical activity level and skinfold thicknesses remained significant. For men 55–68 yr, significant cross-sectional and 2-yr associations were found between higher physical activity level and lower skinfold thicknesses, and higher HDL cholesterol at 5 yr. Higher physical activity continued to be associated with lower skinfold thicknesses and was related to lower systolic blood pressure by the 15-yr examination. Results suggest that most cross-sectional associations between physical activity and risk factors diminish over time, providing support for prospective investigations that find physical activity has a beneficial effect on reduced cardiovascular disease partially independent of traditional risk factors.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SLEIVERT, G. G., R. D. BACKUS, and H. A. WENGER. The influence of a strength-sprint training sequence on multi-joint power output.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1655–1665, 1995. The purpose of this study was to determine whether adaptation to single-versus multi-joint strength training and sprint training was different and whether sequencing strength prior to sprint training was beneficial for increasing power. Thirty-two untrained males were assigned to control (C), sprint-sprint (SS), multi-joint (MJS), or single-joint (SJS) strength-sprint groups. Subjects were tested before training, after 8 wk of strength or sprint training, and after an additional 6 wk of sprint training. By mid-training both SJS and MJS increased 10 repetition maximum strength, but this was not transferable to isometric or isokinetic strength or rate of torque development. SS showed no improvement in these variables. All training groups increased cycle ergometer power output by 8 wk and had similar fiber hypertrophy with no EMG changes. Subsequent sprint training continued to increase maximum power with no further hypertrophy. Tibial nerve conduction velocity increased in all training groups. These results indicate little difference in adaptation to single-and multi-joint strength training. Strength or power improvements caused by training in these modes does not transfer to isometric or isokinetic movements. Further, sequenced strength-sprint training provided no additional power gain over sprint training alone.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BERG, H. E., O. EIKEN, and P. A. TESCH. Involvement of eccentric muscle actions in giant slalom racing.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1666–1670, 1995. Joint angular movements and muscle activation (EMG), were determined in male elite racers while performing the giant slalom. Movement cycles averaged 3.5 ± 0.6 s (left plus right turn), and knee angle ranged 66–114° (180° = straight leg). Knee extensor muscle use was dominated (rectified EMG;P< 0.05) by the leg controlling the outside (downhill) ski during the turn. Time spent while decreasing knee angle (eccentric muscle action) of outside leg averaged 1.0 ± 0.2 s. This phase was longer (P< 0.05) than the average push-off (concentric muscle action) phase of 0.5 ± 0.1 s. Moreover, EMG activity of the outside leg during eccentric muscle actions exceeded (P< 0.05) that of concentric actions and was similar to that attained during maximum isometric knee extension in laboratory tests. Knee and hip angular movement ranged 20–50°. Average joint velocities equalled 20–40°-s-1during the turning phase. Thus, competitive giant slalom skiing is dominated by slow eccentric muscle actions performed at near maximum voluntary force. Because of their greater ability to generate force, eccentric muscle actions may be warranted or even required to resist the G-forces induced during the turn phase.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

PICHON, F., J-C. CHATARD, A. MARTIN, and G. COMETTI. Electrical stimulation and swimming performance.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1671–1676, 1995. The purpose of the study was to examine the influence of a 3-wk period of electrostimulation training on the strength of the latissimus dorsi m. and the swimming performances of 14 competitive swimmers divided into 7 electrostimulated (EG) and 7 control swimmers (CG). The peak torques registered during the flexion-extension of the arm was determined with the help of an isokinetic dynamometer at different velocities (from −60°·s-1to 360°·s-1). Performances were measured over a 25-m pull buoy and a 50-m freestyle swim. For EG, a significant increase of the peak torques was measured in isometric, eccentric, and concentric conditions (P< 0.05). The swimming times declined significantly (P< 0.01) by 0.19 ± 0.14 s, for the 25-m pull-buoy, and by 0.38 ± 0.24 s, for the 50-m freestyle. For CG, no significant difference was found for any of the tests. For the whole group, the variations of the peak torques, measured in eccentric condition (−60°·s-1) were related to the variations of the performances (r = 0.77;P< 0.01). These results showed that an elcctrostimulation program of the latissimus dorsi increased the strength and swimming performances of a group of competitive swimmers.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

RUNDELL, K. W. Treadmill roller ski test predicts biathlon roller ski race results of elite U.S. biathlon women.Med, Sci. Sports Exerc., Vol. 27, No. 12, pp. 1677–1685, 1995. This study evaluated ski-specific laboratory testing and the relationship of test parameters to biathlon race performance. Since the ski skating technique used exclusively during biathlon racing requires a large upper body contribution, treadmill roller ski test parameters may provide relevant information for ski-specific training and ski performance. Seven top U.S. female biathlon skiers performed lactate threshold and &OV0312;O2peak tests running (TR) and roller skiing (skating technique, RS) on a motor driven treadmill. In addition, a constant workload (14 km·h-1, 6% grade) roller ski test to exhaustion at race pace (ET) on a motor driven treadmill, and a short-term double pole power test (DP) were also performed. Results indicate that lactate threshold &OV0312;O2and HR were significantly lower during RS than TR, DP power (w·kg-1) was related to RS &OV0312;O2peak (r = 0.90), but not to TR parameters. ET time to exhaustion was related to gross efficiency during ET (r = −0.86), RS &OV0312;O2peak (r = 0.80) and DP HR (% peak HR, r = 0.80). These results suggest that ski-specific laboratory testing provides better insight to ski performance than treadmill run testing.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

MCCRORY, M. A., T. D. GOMEZ, E. M. BERNAUER, and P. A. MOLÉ. Evaluation of a new air displacement plethysmograph for measuring human body composition.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1686–1691, 1995. A new air displacement plethysmograph, the BOD POD® (BP), was evaluated in comparison to hydrostatic weighing (HW). Sixty-eight adult subjects (26 F, 42 M) varying widely in age (range 20–56 yr), ethnicity, and fatness participated in this study. Same-day test-retest reliability was assessed in a subsample of 16 subjects (9 F, 7 M) and validity was assessed in all subjects (N= 68). The test-retest coefficients of variation (CV) for %FAT measured by BP (%FATBP) and HW (%FATHW) were not significantly different (1.7% ± 1.1% and 2.3% ± 1.9% for BP and HW, respectively (mean ± SD)), indicating excellent reliability for both methods. Validity of percent fat measured by the BP (%FATBP) was also excellent. The mean difference in %FAT (BP -HW) was −0.3 ± 0.2 (SEM), with a 95% confidence interval of −0.6 to 0 %FAT. The regression equation (%FATHW= 1.86 + 0.94 %FATBP; r2= 0.93, SEE = 1.81) was not significantly different from the line of identity (%FATHW= %FATBP), and did not differ by gender. These findings indicate that the BOD POD is a highly reliable and valid method for determining %FAT in adult humans in comparison to HW. This new method has several advantages over HW in that it is quick, relatively simple to operate and may be able to accommodate special populations such as the obese, elderly, and disabled.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

DEMPSTER, P. and S. AITKENS. A new air displacement method for the determination of human body composition.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1692–1697, 1995. A new device based on the plethysmographic measurement of body volume has been developed for the purpose of estimating human body composition. The device, the BOD POD(r) Body Composition System, uses the relationship between pressure and volume to derive the body volume of a subject seated inside a fiberglass chamber. Derivation of body volume, together with measurement of body mass, permits calculation of body density and subsequent estimation of percent fat and fat-free mass. Critical issues which have hampered prior plethysmographic approaches are discussed. The present system's ability to measure the volume of inanimate objects was evaluated for accuracy, reliability, and linearity. Twenty successive tests of a known volume (50,039 ml) on two separate days produced values of 50,037 ± 12.7 ml and 50,030 ± 13.5 ml (mean ± SD) for each day, respectively. The CV for these series were 0.025% and 0.027%. Further testing across a wide range of volumes approximating human size (25–150 1) produced the following regression equation where y = measured volume (I) and x = actual volume (1): y = 0.9998x −0.0274, r2= 1.0, SEE = 0.004 1. The resultant device is likely to enhance opportunities for the quick, simple and noninvasive measurement of body composition for both research and clinical applications.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BASSETT, D. R. Jr. and T. R. FITTON. Gas mixing apparatus for determining cardiac output by CO2rebreathing.Med. Sci. Sports Exert:, Vol. 27, No. 12, pp. 1698–1702, 1995. The carbon dioxide rebreathing technique is widely used for determination of cardiac output during exercise. The equilibration method of Collier et al. (J. Appl. Physiol.9:25, 1956) is generally preferred over the exponential method of Defares (J. Appl. Physiol.13:159, 1968). However, the equilibration method requires the volume and initial CO2percentage in the rebreathing bag to be adjusted according to the work rate. A device for mixing two gases (100% O2and 20% CO2/80% O2) was constructed for this purpose. Multistage regulators are attached to the gas tanks and connected to a medical gas mixer via high-pressure air hoses. A variable time-delay switch causes a solenoid valve to open for 1.0–10 s to deliver a predetermined gas volume. The device was found to accurately deliver a preset volume and concentration of gas to the rebreathing bag. A gas mixing apparatus simplifies the equilibration CO2rebreathing technique by allowing the investigator to easily select the initial volume and percentage of CO2.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

DE KONING, J. J., R. THOMAS, M. BERGER, G. DE GROOT, and G. J. VAN INGEN SCHENAU. The start in speed skating: from running to gliding.Med. Sci. Sports Exerc., Vol. 27, No. 12, pp. 1703–1708, 1995. The purpose of this study was to describe the push-off kinematics in speed skating using three-dimensional coordinates of elite male sprinters during the first part of a speed skating sprint. The velocity of the mass center of the skater's body vC, is decomposed into an “extension” velocity component vC, which is associated with the shortening and lengthening of the leg segment and a “rotational” velocity component vr, which is the result of the rotation of the leg segment about the toe of the skate. It can be concluded that the mechanics of the first strokes of a sprint differ considerably from the mechanics of strokes later on. The first push-offs take place against a fixed location on the ice. In these “running-like” push-offs the contribution of vrin the forward direction is larger than the extension component ve. Later on, the strokes are characterized by a gliding push-off in which vcincreases. In these gliding push-offs no direct relation exists between forward velocity of the skater and the extension in the joints. This allows skaters to obtain much higher velocities than can be obtained during running.

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