摘要:

The perception of effort is multidimensional and it is governed by many physiological, psychological, and experiential factors. This paper deals with a discussion of selected psychological states and traits that are known to be correlated with the expression of effort sense. It has been shown that anxiety, somatic perception, depression, and neuroticism are associated with perceived exertion. Extroversion has been found to be inversely correlated with perceived exertion, and positively correlated with preferred exercise intensity. These empirical findings are congruent with theoretical expectations in each case. It has also been found that perception of effort can be increased and decreased in a systematic manner with various pshcyological interventions such as hypnotic sugestion, dissociativ cognitive strategies, and imagery. Changes in effort sense can also be systematically modified by titrating exericse volume (e.g., overtraining, tapering), and this exercise-induced alteration in perception covaries with affective changes. The research reviewd in this paper supports the conclusion that effort sense is best conceptualized as a complex psychobiological construct as originally proposed by Borg three decades ago.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The perception of breathlessness during physical activities is a frequent and disturbing complaint for patients with chronic respiratory disease. Psychophysical principles can be applied to quantitate the severity of dyspnea during cardiopulmonary exercise testing. Power production (or work) appears to be the most appropriate stimulus for measuring the dyspnea response. The 0–10 category-ratio (CR-10) scale and the visual analog scale (VAS) are two instruments for measuring the intensity of breathlessness. Studies demonstrate that the slope and/or intercept of the power production-breathlessness relationship provide a valid, reliable, and responsive approach for measurement. Ratings of dyspnea during exercise are useful to determine the severity of breathing difficulty and to assess the efficacy of therapy.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Psychophysical scaling of symptoms or discomfort during exercise testing has evolved as an important adjunct to the study of therapeutic interventions in heart disease. One of the major shortcomings of clinical exercise testing, however, has been the assessment of chest pain. Although the presence and characteristics of chest pain have important diagnostic, prognostic, and therapeutic implications, few studies in the literature adequately address chest pain responses to exercise. Clinical trials using exercise as an efficacy parameter frequently use only a single descriptive testing endpoint, such as “moderate” angina. Methods of scaling chest pain during exercise testing are underutilized. Of the several grading systems that have been used, the 0–10 scale developed by Borg has been the most common. It is preferable for patients to relate chest pain sensations during exercise testing to those experienced during daily activities, and treadmill experience improves the reliability and reproducibility of patient responses. This paper examines the methodology and clinical applications of quantifying chest pain during exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Rating of perceived exertion (RPE) is endorsed by the American College of Sports Medicine as a useful adjuvant for prescribing and monitoring exercise intensity. In this paper, I describe a rationale for the use of RPE and other exertional symptoms as an alternative to traditional exercise prescription procedures for healthy adults. Errors associated with using RPE for producing exercise intensity are discussed along with limitations with the use of HRReserve as the standard for judging the accuracy of RPE for prescribing relative exercise intensity. The concept of preferred exertion is discussed as a prescription paradigm that is complementary to the use of perceived exertion and physiological indicators of relative exercise intensity. Important areas that have not received enough research attention are summarized.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

To evaluate the characteristics of runners with exercise-associated collapse (EAC), we studied the time of onset of collapse, rectal temperatures, cardiovascular status, and incidence of readily identifiable medical conditions in 46 male athletes who collapsed during or after a 56-km ultramarathon footrace run on a cool day. Data were compared with 65 control runners who did not collapse in the same race. Weight changes during recovery were studied in a subsample of both groups. The majority (85%) of runners with EAC collapsed after they had completed the race; rectal temperatures (38.5 ± 1.3°C, mean ± SD; range 35.5–42. 0°C) and supine heart rates (87.5 ± 17.2 rain-1; range 60–138) were only modestly elevated. Postrace serum sodium concentrations, changes in plasma volume, and mass during recovery were not significantly different from values in control runners. We conclude that: (i) most cases of EAC (85%) occur after the finish line; (ii) runners collapsing during the race are more likely to have a readily identifiable medical condition than runners collapsing after the finish line; (iii) runners collapse most frequently near cutoff times for medals and race closure times; and (iv) 16% of EAC casualties and 19% of control runners have identifiable biochemical abnormalities.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The purposes of this investigation were to determine: 1) whether the fibrinolytic responses to acute, submaximal exercise were best related to intensity, duration, or total caloric expenditure; and 2) whether the time of day exercise is performed affects the fibrinolytic response. Twelve physically active men (&OV0335; age = 34.8 ± 4.0 yr) performed four 30-min exercise sessions: 50% &OV0312;O2max, a.m. and p.m., and 80% &OV0312;O2max, a.m. and p.m. Blood samples were analyzed for tissue plasminogen activator (TPA) activity and plasminogen activator inhibitor-1 (PAI-1) activity. Data were analyzed using a three-way ANOVA with repeated measures. TPA activity: pre exercise TPA did not differ among the four sessions. TPA increased with exercise in all sessions except the 50% a.m. session. Exercise at 80% increased TPA more than 50% (P < 0.001) and evening sessions increased TPA more than morning sessions (P < 0.05). PAI-1 activity: pre exercise PAI-1 activity was higher during the morning than evening and significantly decreased with exercise in all sessions except the 50% p.m. session. It was concluded that changes in fibrinolytic activity appear to be influenced primarily by exercise intensity rather than duration or total caloric expenditure. Additionally, time of day of exercise performance significantly influenced fibrinolytic activity.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

This study examined the effects of two doses of exercise on tumor incidence and progression, and the number and activity of intratumoral phagocytic cells (80% macrophages [Mψ's]). Male mice were randomly assigned to control (CON), moderate (MOD) or exhaustive (EXH) treadmill running. Mice were inoculated subcutaneously with 2.5 ± 105 mammary adenocarcinoma cells after 3 d of running (3 h after the last run at a point when enhancement in Mψ cytotoxicity is observed). This tumor was chosen due to its susceptibility to Mψ inhibition in vitro and in vivo. Mice continued daily running for 14 d. Food intakes were higher during the last 3 d in MOD and EXH, but body weights were no different. Flow cytometer analysis of tumor masses revealed that MOD had greater numbers of phagocytic cells (vs EXH) with slightly higher phagocytic activities (vs CON and EXH) (P < 0.05). However, no group differences in tumor appearance were seen except on day 7 when CON had less observable tumors than MOD and EXH (P < 0.05). Tumor size was also not different between groups at any point. These results indicate that moderate exercise can increase the phagocytic capacity of intratumoral phagocytic cells, but these changes had no apparent effect on tumor incidence or progression in this study.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Left ventricular function was examined during incremental work rates to maximum using simultaneous determinations of stroke volume, left ventricular ejection time (LVET), and diastolic filling time (DT). Seven endurance trained and seven untrained young adult males were studied on a cycle ergometer at matched heart rates of 90, 120, 140, 160, 180, and 190 bpm (±1 bpm). Stroke volume of the untrained subjects reached a plateau at 120 bpm, but stroke volume of the trained subjects continued to increase to their maximum heart rate with no plateau. Throughout incremental work rates, LVET was significantly longer and DT was significantly shorter in the trained subjects. At a heart rate of 190 bpm, the corresponding rates of ventricular emptying and ventricular filling of the trained versus the untrained subjects were 20% and 71% greater, respectively (P < 0.01). We conclude that during incremental work rates the stroke volume of endurance trained athletes increases progressively to maximum with no plateau. In addition, although trained athletes rely on enhancements in both ventricular filling and ventricular emptying to augment stroke volume, by far their major advantage over untrained subjects is in ventricular filling.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

This study investigated the effects of L-carnitine supplementation on muscle carnitine and glycogen content during submaximal exercise (EX). Triglycerides were elevated by a fat feeding (90 g fat) and 3 h later subjects cycled for 60 min at 70% &OV0312;O2max(CON). Muscle biopsies were obtained preexercise and after 30 and 60 min of EX. Blood samples were taken prior to and every 15 min of exercise. Subjects randomly completed two additional trials following 7 and 14 d of carnitine supplementation (6 g·d-1). During one of the two trials, subjects received 2000 units of heparin 15 min prior to EX to elevate FFA (CNhep); no heparin was administered during the other trial (CN). There were no differences in &OV0312;O2, respiratory exchange ratio, heart rate, or g·min-1 of CHO and fat oxidized among the three trials. At rest serum total acid soluble (TASC) and free (FC) carnitine increased with supplementation (TASC; CON, 71.3 ± 2.9; CN, 92.8 ± 5.4; CNhep, 109.8 ± 3.5 μmol·l-1) (FC; CON, 44.1 ± 2.7; CN, 66.1 ± 5.3; CNhep, 77.1 ± 4.1 μmol·l-1). During EX, TASC remained stable, while FC decreased and short-chain acylcarnitine (SCAC) increased (P < 0.05). Muscle carnitine concentration at rest was unaffected by supplementation. During EX, muscle TASC did not change, FC decreased, and SCAC increased significantly in all three trials. Pre-EX and post-EX muscle glycogens were not different. Increased availability of serum carnitine does not result in an increase in muscle carnitine content nor does it alter lipid oxidation. It appears that there is an adequate amount of carnitine present within the mitochondria to support lipid oxidation.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The effects of regular exercise training on the onset and/or severity of hyperglycemia were studied in female diabetes-prone Biobreeding/Worcester (DP BB/Wor) rats. At 38–39 d of age, animals were weight-matched and randomly assigned to exercise-trained (T) and untrained (Unt) groups. The T rats exercised on a rodent treadmill at a moderate workload, 5 successive days with the 6th day being one of rest. Training lasted 5–11 wk until rats became moribund. Red gastrocnemius muscle citrate synthase activity was significantly higher in T (54.2 ± 4.7 μmol·g-1 ·min-1) compared with Unt (42.9 ± 5.1). No significant difference was found between the T and Unt groups in the following: age at onset of hyperglycemia (T = 82.9 ± 8.7 d; Unt = 82.0 ± 13.5 d, ± SD), ultimate level of hyperglycemia, age of death (T = 89.9 ± 9.2 d; Unt = 89.4 ± 13.9 d), number of days between onset of hyperglycemia and death, or body weights at the onset of hyperglycemia. No significant difference was found between groups in pancreatic insulin concentration (μg·g-1 of protein), T = 0.22 ± 0.04; Unt = 0.20 ± 0.34. These data suggest that a program of regular exercise training may not delay the onset and/or reduce the severity of hyperglycemia in the DP BB/Wor rat. Regular exercise training had no beneficial or detrimental effect on pancreatic beta-cell destruction.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID