Effect of intense strength training on standing balance, walking speed, and sit-to-stand performance in older adults.

BACKGROUND: Muscle size and strength decrease with aging, and the resultant muscle weakness has been implicated in increased risk of falls in older adults. These falls have large economic and functional costs. METHODS: The purpose of this randomized, controlled study was to determine if an 8-week, 3-day per week intense (77.8 +/- 3.4% of 1-repetition maximum [1RM]) strength training program could improve functional ability related to the risk of falling in subjects aged 61--87 years (mean 72, SD 6.3). Twelve strength-training-naive subjects performed two sets of 10 repetitions for six lower body exercises while 12 subjects served as nonintervention controls. Subjects were tested pre-, mid-, and postintervention for strength gain and on three tests of functional ability. RESULTS: Postintervention strength was significantly better (p <.017) in all training subjects across all exercises, and no injuries were reported as a result of either training or 1RM testing. After controlling for preintervention differences, repeated measure analysis of covariance (ANCOVA) found a significant difference between experimental and nonintervention control subjects for postintervention maximal walking speed [F(1,19) = 5.03, p <.05]. There were no significant between-group differences for 1-leg blind balance time or 5-repetition sit-to-stand performance [F(1,19) =.082; F(1,19) =.068, respectively, p >.05]. CONCLUSIONS: These findings suggest that strength training alone does not appear to enhance standing balance or sit-to-stand performance in active, community-dwelling older adults but that it may improve maximal walking speed. The relationship between strength gain and risk of falls remains unclear. The data do reinforce the notion that intense strength training is a safe and effective way to increase muscle strength in this population.

Predictors of referral to cardiac rehabilitation and cardiac exercise self-efficacy.

Cardiac rehabilitation (CR) has known benefits after myocardial infarction (MI) or coronary artery bypass surgery (CABG). Yet, only a small percentage of patients are referred for outpatient CR after hospital discharge. This study investigates patient characteristics related to referral to CR and cardiac exercise self-efficacy, a salient predictor of health behavior change and maintenance. Two hundred nineteen patients enrolled in the study. Of the 185 patients who were CR candidates, 74 were referred to CR. Logistic regression analysis was used to identify variables related to CR referral. Results indicate that patient characteristics of having had fewer MIs or CABGs, having attended CR in the past, and being less physically active during leisure time are related to an increased likelihood of being referred to CR. Multiple regression analysis indicates that leisure physical activity is a predictor of cardiac exercise self-efficacy. Implications for nurses who recruit patients for CR are discussed.

Counseling for physical activity: what primary-care physicians should know.

In Connecticut, 22.1% of the adult population report no physical activity other than activities of daily living. Primary care physicians can play a vital role in the flight against a sedentary lifestyle. As outlined in Healthy People 2000 and the Surgeon General's Report on Physical Activity and Health, the primary-care physician's role in the assessment and advising of physical activity is critical. The primary-care physicians that responded to the Connecticut survey appear to be doing an excellent job in delivering this important message. Recommendations made by the primary-care physician can be a great source of motivation for the patient. The primary-care physician's initial goal should be to get the patient active on a daily basis and than progress to more health-based fitness goals. The patient needs to receive instruction on goal setting, safe exercise tips, and adherence strategies. The primary-care physician's low-cost intervention of advising physical activity can help prevent medical problems in the future. The most current recommendation on physical activity states that, "All U.S. adults should accumulate 30 minutes or more of continuous or intermittent amounts of moderate-intensity physical activity on most, preferably all, days of the week." This latest recommendation offers primary-care physicians a broader range of activities to suggest to their patients. An overwhelming number of research studies indicate that physical activity is a powerful weapon in combating a host of lifestyle-related health problems.

Effects of oral and intravenous rehydration on ratings of perceived exertion and thirst.

The purpose of this investigation was to compare the effects of oral and intravenous saline rehydration on differentiated ratings of perceived exertion (RPE) and thirst. Eight men underwent three randomly assigned rehydration treatments following a 2- to 4-h exercise-induced dehydration bout to reduce body weight by 4%. Treatments included 0.45% saline infusion (i.v.), 0.45% saline oral ingestion (ORAL), and no fluid (NF). Following rehydration and rest (2 h total), subjects walked at 50% VO2max for 90 min at 36 degrees C (EX). Central RPE during ORAL was lower (P < 0.05) than i.v. and NF throughout EX. Local RPE during NF was higher (P < 0.05) than i.v. and ORAL at minutes 20 and 40 of EX and overall RPE during NF was higher (P < 0.05) than ORAL at minutes 20 and 40 of EX. Significant correlations were found between overall RPE and mean skin temperature for i.v. (r = 0.72) and NF (r = 0.75), and between overall RPE and thirst ratings for i.v. (r = 0.70). Thirst ratings were not different among trials at postdehydration. Following rehydration, thirst was higher (P < 0.05) during NF than i.v. and ORAL and lower (P < 0.05) during ORAL than i.v. at all subsequent time points. Results suggest that oral rehydration is likely to elicit lower RPE and thirst ratings compared with intravenous rehydration.

Concentric and eccentric isokinetic lower extremity strength in persons with multiple sclerosis.

This study was supported by the Levine-Rubenstein MS Research Fund and The Rehabilitation Research and Development Service of the U.S. Department of Veterans Affairs. Clinicians might be reluctant to institute exercise training programs for individuals with multiple sclerosis (MS) because so little information is available regarding their muscle performance capability. The purpose of this project was to compare the quadriceps and hamstrings muscle groups' torque capacity of individuals with MS (N = 9) to matched non-MS controls (N = 9). Muscle torques at several speeds were measured using a KIN-COM II isokinetic dynamometer during both concentric (30, 60, and 90 degrees /sec) and eccentric (45, 60, and 75 degrees /sec) contractions. Peak torque for both muscle groups at all velocities were higher for the non-MS group; however, this difference was only significant for the concentric quadriceps muscle contraction (p < .05). All subjects demonstrated higher torque eccentrically than concentrically for the quadriceps, but these differences were only significant for the experimental subjects. The MS group showed a greater decrease in torque with increasing speed than the non-MS group. Deficits between the MS and control groups related to changes in contraction velocity were greater during concentric than eccentric contractions. These findings suggest that strengthening programs that emphasize concentric exercise at the higher of the three speeds of movement included in this study may be most effective in treating this particular type of strength deficit in MS patients. J Orthop Sports Phys Ther 1992;16(3):114-122.

Middle age male distance runners: physiological and psychological profiles.

This study investigated 4 research questions addressing exercise capabilities and psychological characteristics of middle-age (30 to 50 years) male runners. Subjects provided an extensive running history, completed the Multidimensional Anger Inventory, completed the Myers-Briggs Type Indicator, and performed a treadmill running test to volitional exhaustion. Another aspect of the study compared anticipatory and posttest reactions to the treadmill test experience to actual test results. The findings suggest that these runners have common personality profiles, that long-term involvement in running and training is associated with a positive sense of self, and that lifelong aerobic exercise is associated with high cardiovascular fitness. Although the research design does not permit causal or predictive conclusions, the study provides valuable additional baseline information for physicians and fitness professionals who serve middle aged male runners.

The threshold for myocardial ischemia varies in patients with coronary artery disease depending on the exercise protocol.

It is generally accepted that angina pectoris and, presumably, myocardial ischemia occur at a fixed heart rate-systolic blood pressure product in a given patient. This concept of a fixed threshold has recently been challenged. To evaluate the effects of varying exercise intensity on the ischemic threshold, 33 patients with coronary artery disease and provokable myocardial ischemia, documented by thallium-201 myocardial perfusion imaging, underwent two exercise tests 2 to 7 days apart. A symptom-limited incremental treadmill exercise test was followed by a 20 min submaximal treadmill test at an intensity approximating 70% of the peak heart rate attained during the incremental test. During the incremental exercise test, angina pectoris developed in 16 patients and 17 patients were asymptomatic. At least 0.1 mV of ST segment depression developed in all subjects during the incremental exercise test at a mean exercise duration of 5.3 +/- 2.6 min, a rate-pressure product of 19,130 +/- 5,735 and oxygen uptake of 19.6 +/- 7.0 ml/kg per min. During the submaximal exercise test, 28 (85%) of the 33 patients had significant ST segment depression. Of these patients, 24 (86%) were asymptomatic, including 10 patients who had previously reported anginal symptoms during the incremental test. The average time to onset of 0.1 mV ST segment depression during the submaximal test was 8.1 +/- 4.5 min. These changes occurred at a rate-pressure product of 15,250 +/- 3,705 and an oxygen uptake of 14.3 +/- 5.9 ml/kg per min, and were significantly (p less than 0.001) lower than values observed during the graded exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of differential training on isokinetic muscular endurance during acute thermally induced hypohydration.

The purpose of this study was to test the effect of acute thermal hypohydration on the muscle endurance performance of three groups of differentially trained subjects. Group I consisted of six anaerobically trained athletes, Group II consisted of five aerobically trained athletes, and Group III consisted of six sedentary individuals. Experimental trials involved maximal leg extensions performed on a Cybex II dynamometer under conditions of euhydration and hypohydration of minus 3% body weight. Integrated electromyographic data were also collected during each trial to factor out motivation as a variable. The maximum number of leg extension repetitions performed at or above 50% of each subject's peak torque output were compared between treatments and among the three groups. A 2 x 3 factorial analysis of variance (ANOVA) showed a significant decrease in muscle endurance when comparing euhydration to hypohydration among the anaerobically trained subjects as well as among the sedentary subjects (P less than 0.05). The aerobically trained subjects showed no significant decline in muscle endurance when comparing performance under both experimental conditions. It was hypothesized that the training adaptations that occur with aerobic conditioning and are primarily associated with increased plasma volume may be the key to explaining these results.