Joel D. Posner

Low to Moderate Intensity Endurance Training in Healthy Older Adults: Physiological Responses after Four Months

To determine the physiological adaptations in previously sedentary healthy older men and women (mean age = 68) to a 16‐week low‐to‐moderate‐intensity exercise program.

Injuries during the one repetition maximum assessment in the elderly

PURPOSE A decrease in strength, and its associated loss of functional ability is common among the elderly. Although resistance training can reverse this decline, associated injuries with frequently used strength assessments may present a greater risk. METHODS To evaluate the injuries associated with maximal strength evaluations, 83 relatively healthy elderly subjects (40 men and 43 women, 65.8 +/- 6.2 years) with and without prior weight training experience performed 1 repetition maximum testing (1 RM) involving 5 different exercises: chest press, leg extension, abdominal curl, arm curl, and seated calf raise. Subjects were separated into three groups depending on weight training experience, Group 1 had no weight training experience (n = 32), Group 2 had < 6 months of training (n = 24), and Group 3 had > 6 months of training (n = 27). Injury assessment was made 30 minutes, 2 days, and 7 days posttesting. RESULTS Two Group 1 subjects sustained an injury (2.4% of total subjects, 8% of Group 1). Eighty-one subjects safely completed the 1 RM assessment without injury (97.6% of total). Forty-eight of the 83 subjects complained of muscle soreness after testing (58% of total). This complaint alone was not sufficient to be categorized as an injury. CONCLUSIONS These results indicate that 1 RM testing is an acceptable tool in strength evaluations in the elderly. Additional precautions may be needed in inexperienced, elderly individuals to prevent injury.

The use of nuclear magnetic resonance to evaluate muscle injury

Magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) are new and powerful tools to study tissue biochemistry, and to provide precise anatomical visualization of soft tissue structures. This review focuses on the use of these techniques to study exercise-induced muscle injury. MRS measurements show an increase in the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) 1-7 d after eccentric exercise. This increase in Pi/PCr could be due to either increases in extracellular Pi or small increases in resting muscle metabolism. Increased Pi/PCr is also seen during training programs and may indicate persistent muscle injury. Increased resting Pi/PCr with injury was not associated with altered metabolism during exercise. Elevations in resting Pi/PCr have been used to show increased susceptibility of dystrophic muscle to exercise-induced injury. Progressive clinical deterioration in dystrophic dogs is marked by impaired muscle metabolism, and the presence of low oxidative muscle fibers not seen in normal dogs. MRI shows increased proton T2 relaxation times following eccentric exercise that last up to 80 d after injury, and can reflect muscle edema as well as longer lasting changes in the characteristics of cell water. MRI demonstrate precise localization of the injured area, with large differences in both location and degree of injury in different subjects following the same exercise protocol. Thus, MRS can provide information on the metabolic response to injury, while MRI provides information regarding the site and extent of the injury. These tools have promise in helping to understand exercise-induced muscle injury.

Effects of Exercise Training in the Elderly on the Occurrence and Time to Onset of Cardiovascular Diagnoses

To examine the long‐term effects of aerobic exercise on the occurrence and time to onset of cardiovascular diagnoses, 184 initially healthy older subjects were randomized into either a long‐term exercise group (Group A, n = 80), a short‐term exercise group (Group B, n = 42), or a contact control group (Group C, n = 62). After completion of two years in the study, data on new cardiovascular diagnoses and time to onset of these diagnoses in each of the three groups were compared. The occurrence rates for new onset diagnoses were as follows: Group A, 2.5%; Group B, 2%; and Group C, 13%; the average time to onset was greatest for the long‐term exercisers and shortest for the contact control group (P ≤ .02). The results suggest that a regular program of exercise may have cardiovascular benefits for those over 60 years of age.

Exercise capacity in the elderly

One of the primary manifestations of ageing is a reduced ability to respond to physiologic challenges. With aging, the ability to perform exercise and physical work declines and is reflected in the reduction in maximal oxygen consumption. Although this decline is influenced to some degree by the state of health and age, it seems that maintenance of regular physical activity significantly counteracts the loss of aerobic capacity. In healthy old age, the cardiovascular system is able to compensate for certain age-associated declines in cardiac function. A program of endurance training, even when begun in old age, can restore more youthful levels of physical fitness and results in tangible improvements in certain resting, submaximal and maximal indicators of exercise capacity. With comprehensive preexercise clinical screening, physical training can be conducted safely with minimal musculoskeletal problems in the aged. The long-term effects of exercise on morbidity, mortality and psychologic function in old age are unknown.

In Search of Psychological Benefits Exercise in Healthy Older Adults

This study assessed the short-term psychological effects of an exercise training program for 267 healthy elderly volunteers randomly assigned to either a bicycle group that trained three times a week for 4 months or an attention control group that met once a week during the 4-month period. A second aim was to identify predictors of favorable change in either physiological performance in stress-test parameters or in behavioral attributes at the conclusion of training. Psychological assessment procedures included indicators of basic mental health, perceived quality of life, and activity level. One-way repeated-measure multivariate analysis of variance tests revealed only one significant univariate interaction effect: The exercising group showed significantly greater improvement in an index tapping report of feeling better from pretest to posttest as compared to controls. The directions of change for all other measures were uniformly in favor of exercisers but did not approach statistical significance. Behavioral and psychological variables were also found to be irrelevant in predicting improvement in physiological performance at Time 2. These data suggest that exercise program effects on psychological and behavioral indicators were very modest for older adults with very high levels of functioning.

Stroke in the Elderly: I. Epidemiology

Stroke is the third leading cause of death of Americans aged 65 years and older.’ Of the 1,271,656 Americans over age 65 who died in 1979, 144,891 died of stroke.2 Aside from its role in mortality, stroke causes extensive morbidity. One and a half million Americans 65 years and older have had a ~ t r o k e . ~ The prevention and rehabilitation of stroke is one of the leading challenges facing geriatricians today. This article deals with the epidemiology of stroke in the elderly. Subsequent articles will explore its prevention and rehabilitation. 0 The most tantalizing facts to emerge from an epidemiologic examination of stroke in the elderly are : 1. Mortality from stroke in the elderly has been declining, having decreased 37% between 1968 and 1978. 2. Stroke deaths are becoming more concentrated in elderly people who are 85 years and older and less frequent in the young elderly between 65 and 85 years of age.’

Magnetic Resonance Spectroscopy of Muscle Bioenergetics

Publisher Summary Nuclear magnetic resonance ( NMR ) has become a popular tool in the fields of physiology and medicine. While NMR imaging (MRI) has shown its capabilities in terms of imaging anatomical structures, spectroscopy (MRS) provides a wealth of biochemical information. This chapter focuses only on one small aspect of the use of NMR—the use of MRS to study muscle metabolism. It presents a sampling of the kinds of studies that have been performed and the types of questions that MRS has been used to study. The advantage of MRS over other biochemical methods is its noninvasive character. Clinical MRI measurements, with reasonable precautions, are considered to be a minimal or low-risk procedure, and MRS studies require shorter and weaker radiofrequency pulses. MRS has created the ability to investigate the relationship between metabolism and physical activity in a fully functioning system. The noninvasive nature of MRS is an advantage in studies on humans. The problem associated with in vivo MRS is accurate localization of the region of interest. Most MRS studies make use of a surface coil to achieve some form of localization.

The Effect of a Submaximal Exercise Orientation on Cardiopulmonary Cycle Ergometer Stress Test Results in Older Adults

BACKGROUND Orientation sessions are sometimes used to habituate subjects before exercise stress testing. The extent of habituation in older subjects has not been clearly defined. Additionally, the use of repetitive maximal stress testing as an orientation method may not be necessarily applicable in the aged. METHODS To determine if the employment of a submaximal orientation session would effect cardiopulmonary cycle ergometer exercise results, 266 older adults (68.6 +/- 5.0 years) male (n = 100) and female (n = 166) subjects participated in this study. One hundred thirty-one subjects received an orientation before stress testing. One hundred thirty-five did not. RESULTS Analysis of resting values revealed no significant differences. Separate gender analysis was performed at submaximal workloads. Men were examined at 0, 60, and 105 Watts; women at 0, 45, and 75 Watts. Oriented subjects displayed significantly lower heart rates for both males and females at all submaximal workloads. Oxygen uptake was significantly lower for oriented women at 45 Watts (P < or = .05) and men at 60 Watts (P < or = .05). Oriented males displayed significantly lower systolic blood pressure at 0 Watts (P < or = .05), 60 Watts (P < or = .01), and 105 Watts (P < or = .05). The oriented group reached ventilatory threshold (VeT) at a higher workload (P < or = .001), lower heart rate (P < or = .001), and higher VO2 uptake (P < or = .05). Nonoriented subjects obtained a significantly higher maximal heart rate than oriented subjects (147 +/- 15.7 beats per minute (bpm) vs. 140 +/- 17.1 bpm, P < or = .01). Separate gender analysis revealed a significant difference (P < or = .01) in maximal heart rate in males (oriented = 137.4 +/- 18.8 bpm vs. nonoriented = 147.7 +/- 15.7 bpm). Although nonoriented women achieved a higher maximal heart rate, the difference was not significant (146.9 +/- 15.8 bpm vs. 142.6 +/- 16.0 bpm). CONCLUSION These results indicate that both male and female older subjects display significant modification in physiologic performance from habituation after a single submaximal exercise orientation session. This effect was greater at submaximal than maximal workloads, and appears to be greater than that previously reported in younger subjects.