ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Return to training and competition after deep venous calf thrombosis.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 2–5, 1992. A 25-yr-old female triathlete presented with 4 d of increasing left calf pain that started 1 d after an elective termination of pregnancy during the eighth week of gestation. She had been training with running, bicycling, and swimming but did not recall any injury to the calf muscle. Deep venous thrombosis of the calf and popliteal veins was diagnosed, and she was treated with intravenous heparin and oral warfarin anticoagulation. Her major concern was return to training and competition. A protocol was developed based on experience with less active patients and animal studies to allow a progressive return to training activities over 5 wk, followed by running in the sixth week. After release from the hospital, she accelerated the return-to-training protocol and progressed to running within 3 wk. She developed the post-phlebitic syndrome that resolved within 2 yr. The diagnosis and treatment of deep venous thrombosis are reviewed, with specific attention to the needs of athletic patients.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

RIGSBY, L. W., R. K. DISHMAN, A. W. JACKSON, G. S. MACLEAN, and P. B. RAVEN. Effects of exercise training on men seropositive for the human immunodeficiency virus-l.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 6–12, 1992. We examined the effects of chronic exercise on fitness and immune status in Caucasian males (34.9 ± 5.6 yr) diagnosed by Western Wot as seropositive for the HIV-l virus. The exercise regimen involved 12 wk of l h sessions 3 d · wk: 20 min of cycle exercise at 60–80% HRreserve was followed by 35 min of strength and flexibility training. After matching subjects on health status (modified Walter Reed criteria), subjects (N= 37) were randomly assigned to exercise or a counseling control condition. Changes in strength, responses to the YMCA cycle test, and serum lymphocytes were tested by MANOVA in a condition (exercise or counseling)-by-time (pretest, posttest) design with repeated measures on time. Results indicated significant (P< 0.001) group-by-time interactions for strength (N · m) (chest press and leg extension) and for HR (beats · min-1) and tota time (TT) on the cycle test at 150 W. Strength and TT increased and HR decreased in the exercise condition, while control subjects did not change. Total leukocyte, lymphocyte, CD4+, and CD8+ cell counts, and the CD4+/CD8+ ratio were statistically unchanged for each condition. We conclude that HIVl+men, including those symptomatic for AIDS-related complex, can experience significant increases in neuromuscular strength and cardiorespiratory fitness without changes in lymphocyte phenotypes or clinical) diagnosis when the exercise regimen is prescribed and monitored in accordance with ACSM guidelines for healthy adults.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

PITETTI, K. H., M. CLIMSTEIN, K. D. CAMPBELL, P. J. BARRETT, J. A. JACKSON. The cardiovascular capacities of adults with Down syndrome: a comparative study.Med. Sci. Sports Exerc., Vol. 24, No. l, pp. 13–19, 1992. The purpose of this study was to compare the cardiovascular capacities of individuals with Down syndrome (DS) to individuals without Down syndrome who are mentally retarded. Sixteen young adults with DS and 16 individuals without DS (12 males and 4 females, respectively), all with mild/moderate mental retardation, participated in this study. Peak VO2(absolute and relative), VE (I-min-1), heart rate (HR, b · min-1), and RER (VCO2/VO2) were determined by exercise tests utilizing a treadmill (TM) and Schwinn Air-Dyne ergometer (SAE). The best test result was chosen from the TM and SAE tests and used for statistical comparisons. Cardiac output (Q, 1 ± min-1) was measured while standing quietly and while walking at 3 mph, 0% grade, using the CO2rebreathing method for 11 (9 males and 2 females) subjects from each group. Arteriovenous oxygen differences (a-v O2, cardiac index (QI), and stroke volume (SV) were calculated from VO2, Q, HR, and body surface area. Peripheral vascular resistance (PVR), left ventricular work index (LVWI), and left ventricular stroke work index (LVSWI) were calculated from mean arterial pressure, Q, QI, and stroke volume index. Results showed that individuals without DS had statistically significant (P< 0.01) higher mean peak VO2(35.6 vs 24.6 ml · kg-1± min-1± 2567 vs 1683 ml · min-1VE (89.3 vs 59.21/min-1), and HR (179 vs 159 b · min-1) than individuate with DS, respectively. No differences in RER were seen between the groups. No differences were seen in cardiovascular parameters measured while quietly standing. When walking at 3 mph, 0% grade, subjects with DS demonstrated significantly higher mean Q, HR, QI, and LVWI and lower PVR when compared with the subjects without DS. Results of this study strongly suggest that differences do exist between individuals with and without DS in regard to exercise capacities and cardiovascular responses to exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

WALKER, J. A., F. J. CERNY, J. R. COTTER, and H. W. BURTON. Attenuation of contraction-induced skeletal muscle injury by bromeiain.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 20–25, 1992. The proteolytic enzyme, bromelain, reportedly has therapeutic effects in the treatment of inflammation and soft tissue injuries. We tested the hypothesis that bromelain attenuates skeletal muscle injury induced by lengthening contractions. The left extensor digitorum longus (EDL) muscle of anesthetized hamsters was injured using a motorized foot pedal which repeatedly flexed/extended the foot through a range of 125° The EDL muscle was electrically stimulated for 400 ms during plantarflexion. Animals were assigned randomly to either a Od group (evaluated 3-h post-injury) or to untreated (UT) or brome-lain-treated (T) groups, evaluated 3, 7, or 14 d post-injury. Following injury, T received 5 mg · kg-1b.w. of bromelain, twice daily. Maximum isometric tetanic force (P0) was measuredin vitro, then muscles were fixed, sectioned, and examined for evidence of fiber damage. The P of injured muscles from T were higher than P0of injured muscles from UT at 3 (18.7 ± 0.4 vs 16.5 ± N · cm-2and 14 d (20.5 ± 0.6 vs 18.2 ± 0.6 N · cm-2) (P< 0.05), but not 7 d (19.5 ± 0.7 vs 17.7 ± 0.8 N ± cm-2). The P0of injured muscles were significantly lower than P0of contralateral control muscles at all time periods. P0of injured muscles from T were lower than P0from control muscles at 3 and 7 d (P< 0.05), but not 14 d. The number of intact fibers of 3-d UT injured muscles was lower than the number of intact fibers in control muscles (P< 0.05). No difference in fiber number between controls and the 3-d treated group was observed. Thus, daily oral bromelain treatments of 10 mg ± kg-1attenuated the development of contraction-induced injury in hamster EDL muscles.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

SUTTON, J. R. VO2max–new concepts on an old theme.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 26–29, 1992. This symposium VO2max–new concepts on an old theme” is dedicated to the memory of Hermann Rahn, whose inspiration has led many young investigators to explore new horizons. In the debate on factors limiting VO2max at altitude Hermann Rahn stimulated further discussion between those camps supporting the central circulation as limiting VO2max and those proposing a peripheral diffusion limitation.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

SALTIN, B. and S. STRANGE. Maximal oxygen uptake:64old99and64new99arguments for a cardiovascular limitation.Med. Sci. Sports Exerc., Vol. 24, No. l, pp. 30–37, 1992. The research performed over the last 100 yr in regard to oxygen transport during exercise is reviewed. Special focus is on major shifts in views held on which link may limit maximal oxygen uptake of an individual exercising with a large fraction of the muscle mass. Initially the pump capacity of the heart was proposed as the critical factor, a view basically unchallenged until results on the plasticity of muscle came about in the 1960–70s. The capillary bed of the muscle and its mitochondrial volumes can be enhanced with training. These adaptations were then suggested to be prequisites for maximal oxygen uptake to become elevated. The pendulum is slowly swinging back again toward heart and lungs setting the upper limit for the oxygen transport. It appears to be in the range of 80–90 ml ± kg-1± min-1or 150–200 ml ± kg-1muscle ± min-1, which can easily be consumed by a fraction of the muscle mass intensely contracting.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

GREEN, H. J. and A. E. PATLA. Maximal aerobic power: neuromuscular and metabolic considerations.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 38–46, 1992. Differences in maximal aerobic power (VO2max) between individuals have most often been attributed to central processes or processes involved in the uptake and transport of oxygen to the working muscle. This review examines the peripheral or muscular processes that may act as determinants of VO2max. Using progressive cycling exercise and electromyographic techniques, the muscular recruitment and rate coding strategies necessary to realize a VO2max are described. An analysis is also provided of the challenge imposed on the various excitation and contraction processes that occur in the individual muscle cells during progressive exercise. Finally, the review concludes by examining energy metabolic processes and whether it is the availability of oxygen that is limiting to the mitochondria or an inability of the mitochondria to use the available oxygen.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

HONIG, C. R., R. J. CONNETT, and T. E. J. GAYESKI. O2transport and its interaction with metabolism; a systems view of aerobic capacity.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 47–53, 1992. This commentary demonstrates that Vo2max depends, in part, on diffusive O2transport; exercise hyperemia is necessary but not sufficient. Experiments and new mathematical models place the principal site of resistance to O2diffusion between the surface of a red cell and the sarcolemma. The large drop in PO2over this short distance is caused by high flux density and absence of heme protein O2carrier in this region. PO2gradients within red myocytes are shallow at high VO2because myoglobin acts as O2carrier and PO2buffer. At high VO2cell PO2is <5 torr, the myoglobin P50. Low cell PO2relative to blood PO2is essential to a) maintain the driving force on diffusion as capillary PO2falls, and b) to increase myoglobinfacilitated diffusion and the overall O2conductance. O2per sedoes not limit mitochondrial ATP production under normal circumstances because the low O2drive on electron transport is compensated by greater phosphorylation and redox drives. These metabolic adaptations support transacapillary diffusion by defending VO2at the low cell PO2required to extract O2from blood. Thus aerobic capacity is a distributed property, dependent on the interaction of transport and metabolism as a system.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

WAGNER, P. D. Gas exchange and peripheral diffusion limitation.Med. Sci. Sports Exerc., Vol. 24, No. 1, pp. 54–58, 1992. Just what determines maximum O2uptake (VO2max,) has been the subject of much study and discussion over the years, with agreement among investigators still beyond reach. However, the evidence that in normal man VO2max is limited generally by the supply of O2is substantial. Turning to the well-known steps of the pathway for O2from atmosphere to mitochondria, the question then becomes how these steps in fact set the limit to VO2max. This presentation will stress two related hypotheses on how VO2max is set: 1) all steps in the O2pathway interact in a manner that determines VO2max such that an increase (decrease) in the transport capacity for any one step predictably increases (decreases) VO2max, and 2) a major component of this process is the rate at which O2can move by diffusion from Hb in the red cell to the muscle mitochondria. A graphical analysis of this integrative hypothesis is presented with supporting data to show how all transport steps contribute to VO2max. This analysis ties together the ideas and data presented by the other speakers in this symposium, and also leads to predictions that are testable by feasible experiments.

ISSN:0195-9131    

出版商:OVID    

年代:1992

数据来源: OVID