摘要:

UTTER, A. C., R. J. ROBERTSON, D. C. NIEMAN, and J. KANG. Children’s OMNI Scale of Perceived Exertion: walking/running evaluation.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 139–144.PurposeThe Children’s OMNI-walk/run Scale of Perceived Exertion (category range, 0–10) was evaluated using male and female children (6–13 yr of age) during a treadmill graded exercise test.MethodsA cross-sectional, perceptual estimation paradigm using a walking/running test protocol was administered. Oxygen uptake (&OV0312;O2, mL·min−1), %&OV0312;O2max, ventilation (&OV0312;E, L·min−1), respiratory rate (RR, breaths·min−1), respiratory exchange ratio (RER), heart rate (HR, beats·min−1), &OV0312;E/&OV0312;O2ratio, and ratings of perceived exertion (RPE) measurements were made every minute throughout the test.ResultsSignificant correlations were found between OMNI-walk/run Scale RPE responses and &OV0312;O2, %&OV0312;O2max, HR, &OV0312;E/&OV0312;O2ratio, and RR throughout the maximal treadmill exercise test. The strongest correlations were found between RPE and %&OV0312;O2max(r = 0.41–0.60,P< 0.001) and HR (r = 0.26–0.52,P< 0.01).ConclusionThe psychophysiological responses provide validity evidence for use of the Children’s OMNI-walk/run Scale over a wide range of exercise intensities during both walking and running.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

MCMURRAY, R. G., J. S. HARRELL, C. B. BRADLEY, S. DENG, and S. I. BANGDIWALA. Predicted maximal aerobic power in youth is related to age, gender, and ethnicity.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 145–151.PurposeTo determine the effects of age, gender, and ethnicity on the predicted aerobic power of youth as they age from 8 to 16 yr.MethodsThe sample was a multicohort group of 2540 African Americans (N= 543) and Caucasians (N= 1997), 1279 (50.4%) girls and 1261 (49.6%) boys. Heights, weights, and sum of skin folds (triceps + subscapular) were measured. Aerobic power (p&OV0312;O2max), expressed in relative (mL·kg−1·min−1) or absolute (L·min−1) terms, was predicted from a three-stage cycle ergometry test.ResultsQuadratic mixed-model analysis indicated that boys had higher relative and absolutep&OV0312;O2maxthan the girls (P= 0.0004). The African American subjects had a higher absolutep&OV0312;O2max(L·min−1) than the Caucasians, but their relativep&OV0312;O2maxwas lower than the Caucasians (P= 0.031). Finally, age had a significant effect onp&OV0312;O2max(P= 0.0001). The absolutep&OV0312;O2maxof the girls increased 9%·yr−1until age 14; but their relativep&OV0312;O2maxdeclined ∼ 1.2 mL·kg−1·min−1·yr−1. The absolutep&OV0312;O2maxfor the boys increased yearly by ∼ 14% from ages 8 to 16 yr, but the relativep&OV0312;O2maxof the African American males was stable from ages 8 to 11, then dropped, and stabilized again between ages 12 and 16 yr. The relativep&OV0312;O2maxof the Caucasian boys declined from ages 8 to 10, but then increased slightly from age 12 to 16 yr. In addition, the interactions of age and gender, and age squared and gender were significant (P< 0.02).ConclusionThese data indicate that although absolutep&OV0312;O2max(L·min−1) increases from age 8 to 16 yr, relativep&OV0312;O2max(mL·kg−1·min−1) declines. The decline appears to be related to increased fat mass. Similarly, the higher relativep&OV0312;O2max(mL·kg−1·min−1) of the Caucasian youth compared with the African American youth was related to lower weights and skin folds of the Caucasian youth.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

SWAIN, D. P., and B. A. FRANKLIN. &OV0312;O2reserve and the minimal intensity for improving cardiorespiratory fitness.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 152–157.PurposeThe American College of Sports Medicine has stated that aerobic training needs to occur at a minimum threshold intensity of 50% &OV0312;O2maxfor most healthy adults and at 40% &OV0312;O2maxfor those with a very low initial fitness. Recently, the concept of &OV0312;O2reserve (%&OV0312;O2R, i.e., a percentage of the difference between maximum and resting &OV0312;O2) has been introduced for prescribing exercise intensity. This analysis was designed to determine the threshold intensity for improving cardiorespiratory fitness expressed as %&OV0312;O2R units.MethodsPrevious studies in healthy subjects (N= 18) that evaluated the results of training at low-to-moderate intensities (i.e., ≤ 60% &OV0312;O2max) were identified. The original studies described the intensity of exercise variously as %&OV0312;O2max, %HRR, %HRmax, or as a specific HR value. In each case, the intensity was translated into %&OV0312;O2R units.ResultsExercise training intensities below approximately 45% &OV0312;O2R were consistently ineffective at increasing &OV0312;O2maxin studies that used subjects with mean initial &OV0312;O2maxvalues > 40 mL·min−1·kg−1. In studies using subjects with mean initial &OV0312;O2maxvalues < 40 mL·min−1·kg−1, no intensity was found to be ineffective. For this latter group of subjects, the lowest intensities examined were approximately 30% &OV0312;O2R.ConclusionAlthough evidence for a threshold intensity was not strong, this analysis of training studies supports the use of 45% &OV0312;O2R as a minimal effective training intensity for higher fit subjects and 30% &OV0312;O2R for lower fit subjects.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

TAMMELIN, T., S. NÄYHÄ, H. RINTAMÄKI, and P. ZITTING. Occupational physical activity is related to physical fitness in young workers.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 158–166.PurposeWe evaluated the association between occupational physical activity and fitness in young workers, taking into account leisure-time physical activity, body size, and smoking.MethodsThe study population comprised 2188 men and 1987 women, members of the Northern Finland birth cohort 1966, who participated in the 1997–1998 follow-up survey and were employed at the time of the survey. Cardiorespiratory fitness was measured by a 4-min step test and muscular fitness by tests of maximal isometric handgrip and isometric trunk extension. Information on occupational and leisure-time physical activity and smoking was obtained by questionnaire, and body height and weight were measured during medical examination. The data were analyzed by analysis of variance and Cox regression.ResultsMen doing heavy physical work scored better in cardiorespiratory fitness, handgrip strength, and trunk muscle endurance than men doing lighter work; the finding for cardiorespiratory fitness was similar in women. The associations were independent of leisure-time physical activity, body weight and height, and smoking.ConclusionA positive association was found between heavy physical work and a high level of fitness in young workers. Due to limitations of the study setting, causality cannot be asserted, but a training effect of heavy work would not seem unreasonable. Previous studies have suggested a reversal of the positive effect of heavy work on fitness with advancing age. Therefore, regular monitoring of workers’ fitness at an early phase is justified to enable assessment of workers’ capacity for heavy jobs and any possible need for fitness-improving activities.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

KUITUNEN, S., P. V. KOMI, and H. KYRÖLÄINEN. Knee and ankle joint stiffness in sprint running.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 166–173.IntroductionStiffness has often been considered as a regulated property of the neuromuscular system. The purpose of this study was to examine the ankle and knee joint stiffness regulation during sprint running.MethodsTen male sprinters ran at the constant relative speeds of 70, 80, 90, and 100% over a force platform, and ground reaction forces, kinematic, and EMG parameters were collected.ResultsThe results indicated that with increasing running speed the average joint stiffness (change in joint moment divided by change in joint angle) was constant (7 N·m·deg−1) in the ankle joint and increased from 17 to 24 N·m·deg−1(P< 0.01) in the knee joint.ConclusionThe observed constant ankle joint stiffness may depend on (constant) tendon stiffness because of its dominating role in triceps surae muscle-tendon unit. Thus, we conclude that in sprint running the spring-like behavior of the leg might be adjusted by changing the stiffness of the knee joint. However, in complicated motor task, such as sprint running, ankle and knee joint stiffness might be controlled by the individual mechanical and neural properties.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

HELGE, E. W., and I.-L. KANSTRUP. Bone density in female elite gymnasts: impact of muscle strength and sex hormones.Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 174–180.PurposeThe aim of this study was to investigate BMD in Danish female elite gymnasts and the relationships to maximal muscle strength, sex hormone concentrations, and menstrual status.MethodsSix artistic gymnasts, five rhythmic gymnasts, and six controls aged 15–20 yr served as subjects. BMD (g·cm−2) of lumbar spine, proximal femur, distal radius, and whole body were measured by dual-energy x-ray absorptiometry (DXA) scanning. Maximal muscle strength (Nm) was measured in isokinetic trunk extension, trunk flexion, and knee extension. Serum concentrations of estrogen and progesterone in follicular and luteal phases were evaluated.ResultsThree out of six artistic gymnasts had amenorrhea, and two artistic and one rhythmic gymnast experienced oligomenorrhea. BMD in artistic gymnasts was greater than controls (24–45%,P< 0.05) in all sites except whole body. BMD in rhythmic gymnasts was greater than controls (4–26%,P< 0.05) in all sites except distal radius. In gymnasts, BMD correlated to both maximal muscle strength (0.60 < r < 0.85,P< 0.05) and serum progesterone (0.65 < r < 0.75,P< 0.05).ConclusionIn spite of oligomenorrhea or amenorrhea, it is possible for female gymnasts to maintain a high BMD in both the axial (L2–L4) and appendicular skeleton. The correlations between BMD and maximal muscle strength and progesterone concentration in gymnasts may indicate that within the same athletic group, progesterone concentration has a permissive role in bone formation, thus affecting the positive impact of muscle strength.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID