Sally S. Fitts

Six-minute Walk By People With Chronic Renal Failure: Assessment of Effort by Perceived Exertion

ABSTRACT The ability to exercise among 20 people with chronic renal failure was assessed on three tests by measuring the distance walked in 6 min, heart rate change from pre-exercise to postexercise and perceived exertion. Test 1 was conducted to minimize practice effects. Ten participants received exercise coaching for 3 mo between Tests 2 and 3, and 10 individuals were in a control group. Distance walked was highly correlated on the three tests; heart rate change and perceived exertion were only slightly less consistent. Three people changed their perceived exertion by more than one point between Tests 2 and 3, and these changes obscured differences between the exercise and control groups. Exclusion of data for those who changed by more than one point equalized perceived exertion changes in the two groups and revealed a significant (P < 0.05) increase in distance in the exercise group (+21.8 m) but not in the control group (+1.5 m). The study demonstrates that, although perceived exertion ratings are intended for use in incremental exercise testing, they are also valuable for assessing consistency v change in the effort of individual participants in single-intensity testing, such as a self-paced walk.

Body cooling may not improve somatosensory pathway function in multiple sclerosis.

We tested the hypothesis that reducing core body temperature in subjects with multiple sclerosis (MS) improves the cortical somatosensory evoked potential (SEP) response. Twenty subjects with definite MS were compared with 20 subjects without neurologic symptoms or disease. SEPs were recorded with stimulation of the tibial and median nerves unilaterally at 3.1 and 6.1 Hz. The procedure was repeated after a cooking vest and hat reduced core body temperature by an average of 0.46 +/- 0.28 degrees C. No appreciable change in latency or amplitude of the SEP responses occurred in either the control or MS group with cooling. Although the amplitude of the cortical SEP response was less at the 6.1 Hz rate than at 3.1 Hz, there were no statistically significant differences between the MS and control groups or between stimulation rates with cooling. We conclude that, although some reports suggest symptomatic improvements during cooling in subjects with MS, this improvement may not be associated with changes in the SEP.

Physical benefits and challenges of exercise for people with chronic renal disease

Abstract Objective: To evaluate the physical benefits and challenges of exercise for people with chronic renal disease. Data Synthesis: People with chronic renal failure (CRF or predialysis) or end-stage renal disease (ESRD, requiring dialysis) especially need regular exercise because of the many challenges of renal failure. Physiological limitations contribute to subjective fatigue and reduced exercise tolerance, yet lifestyle factors also play an important role. Forced inactivity required during hemodialysis (HD) treatments, post-dialysis fatigue, and frequent bedrest for illness or surgery all contribute to weakness, stiffness, and sedentary habits. Thus, intentional exercise is needed to resist some of the effects of renal disease and its treatment. Exercise capacity in CRFESRD is limited by reduced oxygen supply because of anemia and cardiovascular abnormalities. Oxygen supply only partially accounts for a shift from oxidative to glycolytic muscle metabolism. Muscle strength predicts aerobic exercise capacity better than oxygen supply, indicating muscle dysfunction due to other factors. HD may remove some substance needed for normal muscle metabolism. Carnitine supplementation increases exercise tolerance, but the mechanism is not yet understood. Conclusion: Stationary bicycling during HD is safe and effective, makes fluid removal more efficient, and reduces common complaints such as symptomatic hypotensive episodes, chills, muscle cramping, and post-dialysis fatigue. Exercise during HD also provides supervision and encouragement, which improve compliance. In-center and home exercisers should record activity, duration, and intensity. Perceived exertion is a better guide than heart rate for exercise intensity. Patients need to improve strength and flexibility, as well as aerobic endurance.

Quantification of gaps in the EMG interference pattern in chronic hemiparesis

This study presents a quantification of the impersistence in the EMG interference pattern (IP) produced during maximal effort by patients with chronic hemiparesis. Monopolar needles were used to record from the flexor carpi radialis (FCR) and extensor carpi radialis longus (ECR) muscles of both the paretic and non-paretic sides of 19 patients with a history of unilateral CVA and 10 healthy control subjects during maximal voluntary isometric wrist flexion or extension. We found more gaps in the IP and fewer total seconds of EMG activity in paretic than in non-paretic or control forearm muscles. The number of gaps was similar in paretic FCR and ECR, but the reduced active time in paretic ECR indicates proportionally more gaps per second of EMG activity. This method provides quantitative measures of both the lapses (gaps in the IP during maximal effort and the inability to sustain EMG activity (total seconds) during long contractions. The latter measure is sufficiently sensitive to distinguish the greater impairment of a paretic wrist extensor than a paretic wrist flexor muscle, and both may prove to be valuable for future comparisons of the severity of paresis and the progress of recovery. These results represent the first quantitative confirmation of previous qualitative descriptions of impersistent recruitment.

Behavioral stereotypy in old and young rhesus monkeys

Four old (25 years) and six young (3 years) female rhesus monkeys (Macaca mulatta) were observed individually in a laboratory cage with either an old or a young monkey present as a social partner. The behavioral repertoire was coded into ten mutually exclusive and exhaustive categories. An information analysis of the individual behavior records is presented along with subject and partner age effects on the frequency of bouts and the amount of time spent in each category of behavior. Knowledge of the relative frequencies of the behaviors tells more about the behavior of young than old monkeys; and knowledge of the preceding behavior tells more about the behavior of old than young monkeys. Further, knowledge of the relative frequencies tells more about the behavior of both old and young monkeys with junior or elder partners than with age peers; whereas knowledge of the preceding behavior is more informative for old monkeys than for young ones regardless of the partners age. Both old and young engaged in more affiliative behaviors with age peers than with junior or elder partners. An hypothesis is proposed which relates this social homophyly to the age difference in behavioral stereotypy.

What Is the Optimal Duration of Participation in a Community-Based Health Promotion Program for Older Adults?

Optimizing duration of participation in health promotion programs has important implications for program reach and costs. We examine data from 355 participants in EnhanceWellness to determine whether improvements in disability risk factors (depression, physical inactivity) occurred early or late in the enrollment period. Participants had a mean age of 74 years; 76% were women, and 16% were non-White. The percentage depressed declined from enrollment to 6 months (35% to 28%, p = .001) and from 6 to 12 months (28% to 22%, p = .03). The percentage physically inactive declined over the first 6 months, without substantial change thereafter (47%, 29%, and 29%). Those remaining inactive at 6 months had worse self-rated health and more depressive symptoms initially; a subset of those increased their physical activity by 12 months. These data suggest that enrollment could be reduced from 12 to 6 months without compromising favorable effects of EW participation, although additional benefits may accrue beyond 6 months.

Physical Performance Tests for Dialysis Patients

Physical fuiictioning is an important treatment outcome (1) and is central to renal patients’ concept of quality of life and perception of health (2). Physical function is most often assessed by self-report or report from significant others or healthcare providers, rather than by performance tests. A recent review of health-related quality-of-life measures for end-stage renal disease (ESRD) summarized 92 studies, of which only four included performance testing (3). However, self-report measures often have ceiling effects (i.e., fail to reveal deficits in most patients’ abilities) (4) and low correlations with performance tests (5 ) . For example, 132 chronic dialysis patients reported they had no problems with 40 basic activities of daily living (6). A recent review of renal patients’ functioning and well-being was limited to questionnaire data, but recommended that performance-based assessments should also be used for a better representation of patients’ abilities (7). This review is not comprehensive, but presents the best and most commonly used performance tests for dialysis patients and other people with chronic renal failure (including predialysis, or “pre-D,” and transplant patients) and briefly describes a few new tests. It is important for appropriate performance tests to assess a broad range of abilities, so that the most frail patients are able to achieve a score while the most fit are challenged. Geriatric assessment poses a similar challenge in the wide range of abilities (I) , so some of these tests are derived from that literature; other tests have been used successfully in people with other chronic diseases. Some of the tests described here are functional tests that reflect ordinary activities (e.g., sit-to-stand); other tests evaluate physiological systems (e.g., V0,max) which affect many activities. All performance tests are affected by subjects’ motivation, so careful attention must be paid to selection of subjects (volunteers vs consecutive admissions), instructions, practice, encouragement (8), performance incentives, individual perceptions of effort (9), fatigue, hemodialysis (HD) cycle (during,