摘要:

JELINEK, V. MICHAEL. Exercise induced arrhythmias:their im plications for cardiac rehabilitation programs.Med. Sci. Sports Exercise. Vol. 12, No. 4, pp. 223–230, 1980. The exercise induced frequent ventricular premature beat (VPB) usually indicates the presence of frequent and complex forms of VPB on 24-hr ambulatory monitoring. While it is commonly associated with coronary heart disease (CHD) with abnormalities of left ventricular contraction (LVC) it is not specific for this condition. In the context of CHD with LVC, frequent or complex VPB substantially increase the risk of sudden cardiac death. No therapy is known to reliably suppress VPB and thereby prevent sudden death.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SMART, G.W., J.E. TAUNTON and D.B. CLEMENT. Achilles tendon disorders in runners—a review.Med. Sci. Sports Exercise, Vo. 12, No, 4, pp. 231–243, 1980. The Achilles tendon and the classification, etiology, diagnosis, treatment, and management of Achilles tendon disorders in runners are reviewed. Due to the presence of a paratenon seaeath, the classification of Achilles tendon disease should be revised. Several etiological mechanisms have been proposed in Achilles tendon disease. The authors recognize: faulty foot biomechanics; poor lower leg flexibility; poorly designed athletic footwear; training surfaces; training intensity; overuse through excessive mileage; inactivity; local steroid injections; rheumatic conditions; and indirect violence. An accurate, thorough differential diagnosis is essential when the athlete presents with an Achilles tendon disorder. Except in total rupture and in extensive partial rupture, the authors do not recommend cast immobilization in the treatment of Achilles tendon disease. When the athlete presents with total rupture of the Achilles tendon, the authors believe that surgical repair is the treatment method of choice. Rehabilitation programs to follow successful treatment of Achilles tendon disease are also presented.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

KOBAYASHI, Y., J.A. LOEPPKY, M.D. VENTERS, and U.C. LUFT. Circulation and respiration response to arm exercise and lower body negative pressure.Med. Sci. Sports Exercise, Vol. 12, No. 4, pp. 244–249, 1980: The effects of supine arm exercise and lower body negative pressure (LBNP) were studied in six subjects with 10 min of LBNP at −40 mmHg (L), arm cranking for 8 min at a work load of 225 kpm/min (E) and both combined (L + E) preceded by 2 min of LBNP. Initial responses of ventilation (&OV0312;1) and &OV0312;2were curtailed and heart rate was significantly higher after the first min of L + E than E, reflecting the less accessible venous reservoir and reduced stroke volume due to L. Leg volume was significantly reduced after 30 s of E and continued to decline and remained below baseline during 6 min of recovery. With L + E, leg volume remained constant after E began, indicating both a shift of blood from legs to arms and reduced extravasation with LBNP. End-tidal PO2, &OV0312;1and &OV0312;1/&OV0312;o2were higher and Pco2lower during the latter stages of L + E than during E, indicating less effective lung perfusion and greater alveolar deadspace caused by LBNP. The release of pooled blood from the lower body after L+E caused a greater &OV0312;1, &OV0312;o2and lower RE than after E and produced marked transients in Pco2and Po2, thereby slowing the recovery of gas exchange.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

MARTIN, THOMAS P. and JOHN S. BERNFIELD. Effect of stroke rate on velocity of a rowing shell.Med. Scl. Sports Exercise, Vol. 12, No. 4, pp. 250–256, 1980. In order to examine the effect of stroke rate changes on the velocity-time curve of a rowing shell, the 1976 U.S. Olympic eight-oared crew was filmed rowing six trials each at stroke rates of 37, 39, and 41 strokes per min. Shell instantaneous velocity was calculated and plotted for positions throughout the stroke cycle and a cubic spline curve was fitted to these data points. Actual stroke rate, boat average velocity, and selected parameters of the velocity-time curves were calculated to examine the relationships between variables. In addition, times for phases of the stroke cycle were determined in order to analyze crew technique. Minimum shell velocity occurred approximately 27% into the leg drive phase and maximum velocity occurred during the middle of the seat movement phase. Average minimum shell velocity for all trials deviated −24.4% from the mean velocity while the average maximum velocity deviated + 18.6%. A significant positive relationship (r= .66) was found between stroke rate and average velocity. In analyzing the phases of the stroke cycle, it was determined that increased boat velocity was accomplished by a greater application of force during the drive phase and, more importantly, the exertion of force over a greater percentage of the time for the stroke cycle.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

INGEN SCHENAU, G.J. VAN. Some fundamental aspects of the biomechanics of overground versus treadmill locomotion.Med. Sci. Sporis Exercise, Vol. 12, No. 4, pp. 257–261, 1980. The literature shows a wide difference of opinion about the mechanical equality of, or difference between treadmill and overground locomotion. This difference in opinion is often related to the coordinate system which implicitly or explicitly is used. With help of a few theoretical examples of energy calculations this paper shows that the description of treadmill locomotion with respect to a fixed coordinate system can lead to faulty conclusions. It is concluded that as long as the beltspeed is constant a coordinate system should be used which moves with the belt. In such a system no mechanical difference exists in comparison with overground locomotion with respect to a fixed coordinate system. All differences found in locomotion patterns must therefore originate from other than mechanical causes.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

CLARKSON, PRISCILLA M., WALTER KROLL, and THOMAS C. McBRIDE. Plantar flexion fatigue and muscle fiber type in power and endurance athletes.Med. Sci. Sports Exercise, Vol. 12, No. 4, pp. 262–267, 1980. The relationship between isometric plantar flexion strength fatigue patterns and muscle fiber type composition of the gastrocnemius was assessed in endurance (N = 8) and power (N = 8) trained males. Following baseline strength assessment, subjects were administered two different 25 trial isometric exercise regimens: on one exercise day each 10-sec fatigue trial was separated by a five-sec intertrial rest period, while on the second exercise day the 10-sec fatigue trials were separated by 20-sec intertrial rest periods. Muscle biopsies were secured from the right medial gastrocnemius. Significantly different fatigue patterns resulted between power and endurance groups, with the power group fatiguing five times faster than the endurance group in the 10:5 condition and demonstrating more complex fatigue curves in both exercise conditions. Slow twitch fiber percent number correlated with rate of fatigability as measured by linear trend coefficients in power (r = .84) and endurance groups (r = .26). Rate of fatigability correlated with maximum isometric strength in both power (r = -.66) and endurance (r = -.86) groups. Thus, maximum isometric strength was a better predictor of rate of fatigability than muscle fiber type composition.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SALLEO, ALBERTO, GIUSEPPE ANASTASI, GIUSEPPA LA SPADA, GIUSEPPINA FALZEA, and MARIA G. DENARO. New muscle fiber production during compensatory hypertrophy.Med. Sci. Sports Exercise. Vol. 12, No. 4, pp. 268–273, 1980. Morphological changes exhibited by satellite cells during compensatory hypertrophy have been observed through a scanning electron microscope on m. plantaris of young, adult rats. Compensatory hypertrophy was induced by ablation of the synergistic m. gastrocnemius. Muscles were observed 15, 30, and 60 days postoperative. A consistent increase in wet-weight of m. plantaris (60.3,77.2, and 93.7% more than the contralateral control muscle) indicated the degree of developing hypertrophy. The satellite cells exhibited the following successive changes: (1) cells enlarged and became freed of connective network sheath, (2) cell distance from the associated fibers increased though still attached to the latter, (3) subsequent cell division, giving rise to rows of cells, that with time-lapse formed elongated structures with a common sheath, (4) elongated structures developed into new muscle fibers.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

JACKSON, ALLEN, MARK WATKINS, and ROBERT W. PAT-TON. A factor analysis of twelve selected maximal isotonic strength performances on the Universal Gym.Med. Sci. Sports Exercise, Vol. 12, No. 4, pp. 274–277, 1980. This study sought to isolate and identify the underlying structure of the isotonic strength domain as exhibited on the Universal Gym. Maximal isotonic contractions were elicited from 88 college male subjects involved in a weight training program on 12 selected exercises. Factor analysis was applied to the data to delineate the underlying structure. Analysis of the raw data revealed an unclear nonrobust factor structure. However, when the variance of the anthropometric variables of height and weight were statistically held constant from the raw data, subsequent factor analysis of the statistically controlled data yielded a robust three factor structure. Factor I was related to upper extremity and trunk isotonic strength; Factor II, lower extremity isotonic strength; Factor III, trunk and upper extremity isotonic strength. Thus, when evaluating isotonic strength responses on the Universal Gym, upper, lower extremity and trunk measures as body segments should be utilized; also, anthropometric measures of height and weight should be considered.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

GRAHAM, T., B.A. WILSON, M. SAMPLE, J. VAN DIJK, and A. BONEN. The effects of hypercapnia on metabolic responses to progressive exhaustive work.Med. Sci. Sports Exercise, Vol. 12, No. 4, pp. 278–284, 1980. Altering CO2storage has been shown to influence lactate metabolism. However, the metabolic effects on man during physical activity have not been well documented. Subjects (n = 8) performed a progressive bicycle test (beginning at O and increasing 30 W every 4 min to exhaustion) on two occasions (once inspiring compressed air and once 4% CO2and 21% O2). The work time, peak Vo2, VCO2, and HR achieved were the same in the two trials for each subject. The VI was significantly (p<0.05) elevated throughout the CO2work and the recovery. The O2debt increased from a mean of 5.87 to 7.761 with CO2. although the difference was not significant. Blood lactate was lower (p<0.05) from the onset of the work and throughout both the exercise and the 30 min. recovery period. Peak lactate was decreased from a mean of 9.59 to 6.99mM-1-1. The oxygen cost of the work was not altered but the blood lactate response to the activity was significantly depressed. The reduction in lactate could be due to glycolytic inhibition and enhanced fat metabolism. The data support, but do not prove, this hypothesis.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

MARTIN, BRUCE J., CLIFFORD W. ZWILLICH, and JOHN V. WEIL. Morphine reduces ventilation without changing metabolic rate in exercise.Med. Sci. Sports Exercise, Vol. 12, No. 4, pp. 285–287, 1980. Morphine reduces ventilation (VE) in exercising man. The mechanism of this ventilatory depression remains unclear. Recent evidence suggests that morphine may reduce exercise VEby simultaneously reducing exercise metabolic rate. We measured exercise VEin six normal subjects after intravenous injection of either saline or 0.1 mg/kg morphine sulfate. During treadmill walks requiring 1/3 and 1/2 of the maximal oxygen uptake, morphine reduced VE(P<0.05), while it left metabolic rate unchanged. Morphine treatment elevated end-tidal Pco2at both work levels (P<0.05). Lower VEand higher PETco2in exercise after morphine persisted after elevation of alveolar Po2to 200 torr. Thus, morphine left unchanged the contribution of the hypoxic chemoreflex to normoxic exercise VE. In addition, morphine failed to alter the ventilatory responses to hypercapnia measured at each exercise level. These results suggest that analgesic dosages of morphine reduce the ventilatory response to exercise through a mechanism other than alterations in metabolic rate or chemical ventilatory responses.

ISSN:0195-9131    

出版商:OVID    

年代:1980

数据来源: OVID