摘要:

Y. BHAMBHANI and M. SINGH. Metabolic and cinematographic analysis of walking and running in men and women.Med. Sci. Sports Exerc., Vol. 17, No. l, pp. 131–137, 1985. The purposes of this study were to compare the total metabolic costs and gait patterns of walking and running at self-selected, comfortable speeds in males and females. Total oxygen consumption was used to determine the metabolic cost, and cinematographic analysis was used to study the gait patterns of walking and running a distance of 1 km in 12 male and 12 female subjects. No significant sex difference was observed for the speed, vertical lift per stride, and total vertical lift per km of distance walked. Females ran at a significantly slower speed than males (P< .01), but no significant sex difference was observed for the vertical lift per stride or total vertical lift per km of distance run. In both sexes, the gross and net energy costs of running were significantly greater (P< .001) than those of walking when values were expressed as kcal · kg-1· km-1or cal · kg-1· stride-1. No significant sex difference was observed in the gross or net metabolic cost of walking, whereas during running, the gross and net metabolic costs in kcal · kg-1· km-1were significantly higher (P< .05) in females than in males. It was hypothesized that this sex difference was due to the cumulative effect of several factors which were biomechanical and metabolic in nature.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

M.M. COWAN and L.W. GREGORY. Responses of pre- and post-menopausal females to aerobic conditioning.Med. Sci. Sports Exerc. Vol. 17, No. 1, pp. 138–143, 1985. This study sought to determine whether the ability to improve cardiorespiratory endurance and body composition is affected by the menopausal status of females. Twenty premenopausal females and 18 postmenopausal females, ages 35–49 and 47–66 yr, respectively, were randomly assigned to exercise and control groups depending on menopausal status. Both exercise groups (PRE-EX,N= 16; POST-EX,N= 14) participated in a progressive walking program (4 days/week for 9 weeks) at an intensity of 80% the age-adjusted heart rate maximum (80% HRM). Following training, both exercise groups significantly improved submaximal exercise capacity (SEC) as measured by oxygen consumption (l/min; ml/kg-min) and treadmill walking time at 80% HRM. The PRE-EX group significantly improved percent body fat and lean body weight, while there was no significant change in total body weight. The POST-EX group significantly improved total body weight and percent body fat with no significant change in lean body weight. Although some of these changes in body composition were statistically significant, overall the alterations were minimal. ANCOVA revealed exercise, not menopause, to be the effective treatment for improving percent body fat and SEC80%HRM. There were no significant differences between the PRE-EX and POST-EX groups in their ability to improve SEC80%HRMor to reduce percent body fat. The POST-EX group had a significantly greater reduction in total body weight, while the PRE-EX group had significantly greater increases in lean body weight. These findings suggest that the ability to favorably alter body composition and cardiorespiratory endurance through the aerobic conditioning of females is independent of menopausal status.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

T. D. FAHEY, M HARVEY, R. V. SCHROEDER, and F. FERGUSON. Influence of sex differences and knee joint position on electrical stimulation-modulated strength increases.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 144–147, 1985. This study examined the influence of sex differences and knee joint position on the effectiveness of isometric electrical stimulation in improving isometric and isokinetic strength. Twenty-seven females and 28 male subjects were assigned to either a control group (C) that received no electrical stimulation, to an experimental group that received stimulation of the quadriceps with the knee flexed at 65° (EF), or to an experimental group that received electrical stimulation of the quadriceps with the knee fully extended (EE). Experimental subjects received 15 min of electrical stimulation 3 times/wk for a total of 6 wk. Before and after the study, knee extension strength was measured with a Cybex II, isometrically at 65° of knee flexion and isokinetically at 30· °s-1, 60° · s-1, 90° ·s-1, and 120°s-1. Multivariate analysis of covariance, using the pretests as the covariate, revealed no sex differences in responsiveness to electrical stimulation. EF was superior to EE at 30° ·s-1and 120° ·s-1in females and at 120° ·s-1in males (P< 0.05). Male and female EF was superior to C in all tests. EE was higher than C at isometric, 30° ·s-1, 90° ·s-1, and 120° ·s-1in females and at isometric and 30° ·s-1in males. These data suggest that electrical stimulation at the quadriceps can increase isometric and isokinetic strength and may be more effective in improving isokinetic strength if the knee is flexed during treatment.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

S. SAKURAI and M. MIYASHITA. Mechanical energy changes during treadmill running.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 148–152, 1985. The purpose of this study was to investigate mechanical energy changes during treadmill running, using two biomechanical models of the human body: the multi-segment model and the center of mass model. Two university distance runners ran at 3.33 and 2.67 m/s on the treadmill, while the right side was filmed by a 16°mm high-speed movie camera (100 fps). The instantaneous mechanical energies of the multi-segment model composed of 11 rigid segments (ME total) and those of the C.M. model (ME C.M.) were calculated for two strides for each trial. The following results were obtained: (1) the trunk segment was the major contributor to the body energy variations, compared to the four limbs; (2) internal kinetic energy, which was the difference between the energy amounts of the two models, was found to have a phase relationship directly opposite to those of the C.M. model. These findings were contrary to the previous studies on walking and were seen to be important characteristics of running energetics.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

J. PIVARNIK, T. KAYROUZ, and L. C. SENAY, JR. Plasma volume and protein content in progressive exercise: influence of cyclooxygenase inhibitors.Med. Sci. Sports Exerc. Vol. 17, No. 1, pp. 153–157, 1985. Non-steroidal anti-inflammatory compounds such as ibuprofen and naproxen reduce volume loss in sheep following injection of endotoxin. We investigated whether these drugs would change the course of plasma volume reduction during progressive exercise on a cycle ergometer. Subjects [15 males; age (X±SD), 26.3±8.3 yr; height, 180.3±4.5 cm; weight, 76.8±8.0 kg; peak &OV0312;O2, 3.8±0.6 l·min-1] exercised for 5 min at 20, 30, 40, 50, 60, and 70% of peak &OV0312;O2with and without a 24-h pre-treatment with either ibuprofen or naproxen. The two tests for each subject were done a week apart. Blood samples were drawn before and after each exercise level. Based on blood analysis, cyclooxygenase inhibitors significantly altered the retention of protein within the vascular volume during exercise. That is, the degree of concentration of protein per unit of plasma volume loss during exercise was less with drug treatment. In spite of this, ibuprofen and naproxen did not influence fluid shifts during exercise. Use of cyclooxygenase inhibitors probably increased the permeability of vascular endothelium to large molecules, which was only evident when hydrostatic and osmotic events in muscle capillaries caused an increase in bulk flow across the capillary walls.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

LEEN, BURKETT, WENDY M. KOHRT, and RICHARD BUCHBINDER. Effects of shoes and foot orthotics on &OV0312;O2and selected frontal plane knee kinematics.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 158–163, 1985. The objective of this study was to investigate the effects of shoes and foot orthotics on running economy and selected frontal plane knee kinematics during the support phase of running. Twenty-one male runners who had been fitted with orthotics served as subjects. Subjects participated in three submaximal runs on a treadmill under the following conditions: (1) barefoot, (2) shoes, and (3) shoes plus orthotics. A run consisted of 1 min at 161 m· min-1, 2 min at 180 m·min-1, and 4 min at 201 m·min-1. &OV0312;O2was calculated for the last 3 min of each test. Frontal plane motion was filmed during the sixth min of each submaximal run, and linear and angular displacement of the knee were then calculated from film data.Results from the mechanical aspect of this study indicate that there were no significant differences among the means for linear displacement of the knee. Angular displacement of the knee during barefoot running was significantly (P< 0.05) less than shoe and shoe-plus-orthotic conditions. There was no difference, however, between shoes and shoes plus orthotics. The economy results revealed that the aerobic cost of running increased as the amount of mass added to the foot increased. In absolute terms (1min-1), running in shoes plus orthotics was significantly (P< 0.05) more costly than running barefoot. It appears that if orthotics do, in fact, improve running economy by improving running mechanics, the amount of improvement is negated by the additional cost of running associated with the mass of the orthotics.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

P.R. BENDER and B.J. MARTIN. Maximal ventilation after exhausting exercise.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 164–167, 1985. It remains unclear whether the hyperpnea of exercise severely stresses the ventilatory musculature. We hypothesized that the ability to ventilate maximally is decreased during and immediately following exhausting exercise. Subjects performed isocapnic maximal voluntary ventilations (60-s MVV) before, during the final minute, and after exhausting treadmill exercise lasting either 3–10 min or 60 min. Severe exercise lasting 3–10 min failed to change the 60-s MVV. In contrast, during the final minute and 5 and 10 min after 60 min of exhausting exercise, eight non-runners showed significantly lower (P< 0.01) 60-s MVV values in comparison to control values. Eight runners had a lower (P< 0.05) 60-s MVV 10 min post-exercise as compared with control and exercise values. Our data suggest that the capacity to ventilate maximally declines only in long-term exhausting exercise and that this decrement in most pronounced in non-runners.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

F.I. KATCH, P.S. FREEDSON, and C.A. JONES. Evaluation of acute cardiorespiratory responses to hydraulic resistance exercise. Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 168–173, 1985. Accurate evaluation of the acute responses to resistance exercise training depends on the stability of the criterion measures. This is particularly true for maximal effort exercise where continuous “all-out” effort for each repetition is encouraged. The present study evaluated reliability of repetition number (repN), respiratory gas parameters (&OV0312;O2,&OV0312;CO2, &OV0312;E), and heart rate (HR) for shoulder (SE), chest (CE), and leg (LE) exercise performed maximally on a single-unit, 3-station hydraulic resistance exercise machine (Hydra-Fitness, Belton, TX). On 2 separate days, 20 college men completed three 20-s bouts of SE, CE, and LE with a 204 rest between bouts and 5 min between exercise modes. There were no significant differences between bouts or test days for repN, gas measures, or HR. Subjects performed 17, 19, and 21 reps during SE, LE, and CE. &OV0312;O2was 1.7 I-min-1(24.3 ml.kg-1.min-1) for SE, 1.87 I-min-1(25.5 ml.kg-1.min-1) for CE, and 2.1 I-min-1(28.6 ml.kg-1.min-1) for LE. These values, averaged, represented 52.8% of the max &OV0312;O2determined on a continuous cycle ergometer test. The corresponding HR's during hydraulic exercise averaged 84.6% of HR max. Test-retest reliability coefficients ranged from r=.67 to .87 for repN, r=.41 to .83 for gas measures, and r=.72 to .89 for HR. The MET level averaged 7.5 (heavy), and caloric expenditure per minute averaged 35% higher compared with literature values for free weights and 29.4 and 11.5% greater than circuit exercise on Nautilus or Universal Gym equipment, respectively. It is concluded that there are reliable individual differences in repN, respiratory gas parameters, and HR during maximal effort exercise of relatively short duration performed on a multiple-station hydraulic resistance exercise apparatus.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

D.C. CASAL and A.S. LEON. Failure of caffeine to affect substrate utiization during prolonged running.Mod. Sci. Sports Exerc., Vol. 17, No. 1, pp. 174–179, 1985. Nine sub-3-h male marathoners performed three 45-min monitored treadmill runs at approximately 75% of &OV0312;O2maxduring a 2-wk period. The men were assigned in a random, double-blind fashion following the control run to receive either 350 ml of decaffeinated coffee or 350 ml of decaffeinated coffee with 400 mg of caffeine added 1 h before the second run with crossover to the other beverage for the third run. Venous blood was analyzed for free fatty acids, triglycerides, glucose, and lactic acid before beverage consumption and before and after each run. Oxygen consumption (&OV0312;O2), carbon dioxide production (&OV0312;CO2), respiratory exchange ratio (R), ventilation (E), and perceived exertion were measured at 15,30, and 45 min of each run. Of the blood parameters, free fatty acid and lactic acid concentration increased following caffeine ingestion. There was no difference in &OV0312;O2, &OV0312;CO2, or R between the three runs. Perceived exertion showed a significant decrease (P< 0.05) at each time point in caffeine added and decaffeinated compared to control. Triglycerides, glucose, and lactic acid increased similarly in all three runs. In these well-trained marathoners, although plasma free fatty acids were elevated significantly prior to exercise after caffeine ingestion, there was no indirect evidence of altered substrate utilization during subsequent treadmill running.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID