Effect of Baseline BMI and IL-6 Subgroup Membership on Gait Speed Response to Caloric Restriction in Older Adults with Obesity

BACKGROUND

Prior work shows caloric restriction (CR) can improve physical function among older adults living with obesity. However, the contribution of starting weight and inflammatory burden to CR-associated functional improvements is unclear. The primary purpose of this study was to determine if CR-associated gait speed change varied by body mass index (BMI) and plasma interleukin 6 (IL-6) at baseline and secondarily to determine the contribution of BMI change and IL-6 change to gait speed change.

DESIGN, SETTING, PARTICIPANTS

Data from eight randomized control trials were pooled, with 1184 participants randomized to CR (n=661) and No CR (n=523) conditions. All studies assessed outcomes before and five or six months after assignment to CR or No CR.

MEASUREMENTS

BMI and IL-6 were assessed at baseline using standard procedures. Gait speed was assessed with the six-minute walk test or 400m walk test. Baseline BMI/IL-6 subgroups were constructed using BMI≥35 kg/m2 and IL-6>2.5 pg/mL thresholds. Participants with BMI≥35 kg/m2 were grouped into class 2+ obesity and BMI<35 kg/m2 into class 1- obesity; IL-6>2.5 pg/mL were grouped into high IL-6, and <2.5 pg/mL as low IL-6 (class 2+ obesity/high IL-6: n=288, class 2+ obesity/low IL-6: n=143, class 1- obesity/high IL-6: n=354, or class 1- obesity/low IL-6: n=399). All analyses used adjusted general linear models.

RESULTS

Gait speed significantly improved with CR versus non-CR [mean difference: +0.02 m/s (95% CI: 0.01, 0.04)]. CR assignment significantly interacted with BMI/IL-6 subgroup membership (p=0.03). Greatest gait speed improvement was observed in the class 2+ obesity/high IL-6 subgroup [+0.07 m/s (0.03, 0.10)]. No other subgroups observed significant gait speed change. For each unit decrease in BMI, gait speed change increased by +0.02 m/s (p<0.001; R2=0.26), while log IL-6 change did not significantly affect gait speed change [+0.01 m/s (p=0.20)].

CONCLUSIONS

Only the class 2+ obesity/high IL-6 subgroup significantly improved gait speed in response to CR. Improvement in gait speed in this subgroup was driven by a larger decrease in BMI, but not IL-6, in response to CR. Individuals with class 2+ obesity and high IL-6 are most likely to show improved gait speed in response to CR, with improvement predominantly driven by reductions in BMI.

The Effects of a Pain Management-Focused Mobile Health Behavior Intervention on Older Adults' Self-efficacy, Satisfaction with Functioning, and Quality of Life: a Randomized Pilot Trial

BACKGROUND

This report investigates the impact of a remote physical activity intervention on self-efficacy, satisfaction with functioning, and health-related quality of life (HRQOL) as assessed by the SF-36 in obese older adults with chronic pain. The intervention was group-mediated in nature and based in social cognitive theory and mindfulness-based relapse prevention.

METHODS

Participants (N = 28; 70.21 ± 5.22 years) were randomly assigned to receive either the active intervention, which focused on reducing caloric intake and increasing steps across the day or to a waitlist control condition.

RESULTS

Over 12 weeks, intervention participants reported a moderate, positive improvement in self-efficacy for walking relative to control. They also reported large magnitude improvements in satisfaction for physical functioning as well as improvements on pain and the physical functioning subscales of the SF-36.

CONCLUSIONS

These findings expand on previous research showing similar effects in response to structured exercise, this time via a protocol that is likely to be scalable and sustainable for many older adults. Additional work on larger and more diverse samples is warranted.

Relationships between respiratory sinus arrhythmia and stress in college students

The purpose of this study was to examine the relationships between university students' respiratory sinus arrhythmia (RSA) profiles and both retrospective and momentary ratings of stress. Participants were undergraduate students enrolled in an introductory health science course (N = 64). Participants provided RSA data at rest (tonic) and following an orthostatic challenge (phasic), completed the 10-item Perceived Stress Scale (PSS), and completed 6 daily ecological momentary assessments (EMA) of stress for 1 week. Higher tonic RSA was associated with lower perceived stress assessed via PSS and average EMA responses. Those with higher tonic RSA did not differ in their experience of stress across the week, whereas those with lower tonic RSA experienced increased stress across the week, and these trajectories varied as a function of phasic responses. These findings suggest a need for greater emphasis on behavioral strategies for maintaining and enhancing autonomic nervous system health among college students.

Empowered with Movement to Prevent Obesity & Weight Regain (EMPOWER): Design and methods

Promoting lasting weight loss among older adults is an important public health challenge. Participation in physical activity aids in weight loss and is important for the maintenance of physical function and quality of life. However, traditional intensive lifestyle interventions place a focus on discrete bouts of structured activity, leaving much of the remainder of the day for sedentary behavior. Structured exercise and weight loss programs often produce short-term weight loss that is typically followed by weight regain, and older adults are more likely to regain weight as fat mass rather than lean mass. Preliminary evidence suggests a focus on day-long movement intended to minimize time spent sitting produces better short-term weight loss and weight maintenance. Herein we describe the design and methods for a three-arm randomized controlled trial comparing mHealth-supported weight loss (WL) + structured exercise (EX); WL + a novel daily movement intervention (SitLess); and WL + EX + SitLess. Older adults (N = 180) will be randomly assigned to one of the three interventions, each comprised of a 6-month intensive phase; a 3-month transition phase; and a 9-month maintenance phase. The primary aim of the study is to determine whether the addition of SitLess to a traditional intensive lifestyle intervention comprised of dietary weight loss and structured exercise produces a larger 18-month reduction in body weight relative to WL + EX and WL + SitLess.

Development of Subject-Specific Proximal Femur Finite Element Models Of Older Adults with Obesity to Evaluate the Effects of Weight Loss on Bone Strength

Study background

Recommendation of intentional weight loss in older adults remains controversial, due in part to the loss of bone mineral density (BMD) known to accompany weight loss. While finite element (FE) models have been used to assess bone strength, these methods have not been used to study the effects of weight loss. The purpose of this study is to develop subject-specific FE models of the proximal femur and study the effect of intentional weight loss on bone strength.

Methods

Computed tomography (CT) scans of the proximal femur of 25 overweight and obese (mean BMI=29.7 ± 4.0 kg/m²), older adults (mean age=65.6 ± 4.1 years) undergoing an 18-month intentional weight loss intervention were obtained at baseline and post-intervention. Measures of volumetric BMD (vBMD) and variable cortical thickness were derived from each subject CT scan and directly mapped to baseline and post-intervention models. Subject-specific FE models were developed using morphing techniques. Bone strength was estimated through simulation of a single-limb stance and sideways fall configuration.

Results

After weight loss intervention, there were significant decreases from baseline to 18 months in vBMD (total hip: -0.024 ± 0.013 g/cm³; femoral neck: -0.012 ± 0.014 g/cm³), cortical thickness (total hip: -0.044 ± 0.032 mm; femoral neck: -0.026 ± 0.039 mm), and estimated strength (stance: -0.15 ± 0.12 kN; fall: -0.04 ± 0.06 kN). Adjusting for baseline bone measures, body mass, and gender, correlations were found between weight change and change in total hip and femoral neck cortical thickness (all p<0.05). For every 1 kilogram of body mass lost cortical thickness in the total hip and femoral neck decreased by 0.003 mm and 0.004 mm, respectively. No significant correlations were present for the vBMD or strength data.

Conclusion

The developed subject-specific FE models could be used to better understand the effects of intentional weight loss on bone health.

Mediators of Increased Physical Activity and Change in Subjective Well-being: Results from the Activity Counseling Trial (ACT)

The purpose of this study was to examine whether change in satisfaction with physical function (SF), satisfaction with physical appearance (SA), and self-efficacy (SE) mediate the effects that increased physical activity has on change in subjective well-being (SWB). Participants in this investigation consisted of 854 men (n = 471) and women (n = 383) who took part in the Activity Counseling Trial (ACT). ACT was a 24-month multicenter, randomized controlled trial to evaluate the effectiveness of interventions to promote physical activity in the primary care setting. Participants were assigned to one of three treatments: standard care control, staff-assisted intervention, or staff-counseling intervention. Results revealed that, irrespective of treatment arm, change in physical activity was related to change in SBW and to change in all mediators of interest. A statistical test of mediation revealed that the influence of change in physical activity on SWB was due to change in all three mediators with change in SF making the greatest contribution to the model.

Obesity, intentional weight loss and physical disability in older adults

We examine obesity, intentional weight loss and physical disability in older adults. Based on prospective epidemiological studies, body mass index exhibits a curvilinear relationship with physical disability; there appears to be some protective effect associated with older adults being overweight. Whereas the greatest risk for physical disability occurs in older adults who are ≥class II obesity, the effects of obesity on physical disability appears to be moderated by both sex and race. Obesity at age 30 years constitutes a greater risk for disability later in life than when obesity develops at age 50 years or later; however, physical activity may buffer the adverse effects obesity has on late life physical disability. Data from a limited number of randomized clinical trials reinforce the important role that physical activity plays in weight loss programmes for older adults. Furthermore, short-term studies have found that resistance training may be particularly beneficial in these programmes as this mode of exercise attenuates the loss of fat-free mass during caloric restriction. Multi-year randomized clinical trials are needed to examine whether weight loss can alter the course of physical disablement in aging and to determine the long-term feasibility and effects of combining resistance exercise with weight loss in older adults.

Treatment of minor depression in older adults: a pilot study comparing sertraline and exercise

The purpose of this study was to conduct a pilot clinical trial to test the feasibility and efficacy of an exercise program and anti-depressant treatment compared with usual care in improving the emotional and physical functioning of older adults with minor depression. Participants were 37 older adults with minor depression who were randomized to exercise, sertraline, or usual care; 32 participants completed the 16-week study. Outcomes included measures of both emotional (clinician and self-report) and physical (observed and self-report) functioning. There were trends for the superiority of the exercise and sertraline conditions over usual care in improving SF-36 mental health scores and clinician-rated depression scores. Individuals in the exercise condition showed greater improvements in physical functioning than individuals in the usual care condition. Both sertraline and exercise show promise as treatments for late-life minor depression. However, exercise has the added benefit of improving physical functioning as well.

Physical exercise and the prevention of disability in activities of daily living in older persons with osteoarthritis

BACKGROUND

The prevention of disability in activities of daily living (ADL) may prolong older persons' autonomy (older persons are defined in this study as those aged > or =60 years). However, proved preventive strategies for ADL disability are lacking. A sedentary lifestyle is an important cause of disability. This study examines whether an exercise program can prevent ADL disability.

METHODS

A 2-center, randomized, single-blind, controlled trial was conducted in which participants were assigned to an aerobic exercise program, a resistance exercise program, or an attention control group. Of the 439 community-dwelling persons aged 60 years or older with knee osteoarthritis originally recruited, the 250 participants initially free of ADL disability were used for this study. Incident ADL disability, defined as developing difficulty in transferring from a bed to a chair, eating, dressing, using the toilet, or bathing, was assessed quarterly during 18 months of follow-up.

RESULTS

The cumulative incidence of ADL disability was lower in the exercise groups (37.1%) than in the attention control group (52.5%) (P =.02). After adjustment for demographics and baseline physical function, the relative risk of incident ADL disability for assignment to exercise was 0.57 (95% confidence interval, 0.38-0.85; P =.006). Both exercise programs prevented ADL disability; the relative risks were 0.60 (95% confidence interval, 0.38-0.97; P =.04) for resistance exercise and 0.53 (95% confidence interval, 0.33-0.85; P =.009) for aerobic exercise. The lowest ADL disability risks were found for participants with the highest compliance to exercise.

CONCLUSIONS

Aerobic and resistance exercise may reduce the incidence of ADL disability in older persons with knee osteoarthritis. Exercise may be an effective strategy for preventing ADL disability and, consequently, may prolong older persons' autonomy.

Physical activity and quality of life in older adults

Although there has been increased research and clinical attention given to the effects that physical activity has on quality of life among older adults, there is a lack of consistency surrounding the use of this term. As a result, attempts to examine what causes change in quality of life have been limited. This article critically reviews the literature on physical activity and quality of life in older adults. In so doing, attention is given to both quality of life as a psychological construct represented by life satisfaction as well as a clinical and geriatric outcome represented by the core dimensions of health status or health-related quality of life. The literature is also examined to identify potential mediators and moderators in the physical activity and quality-of-life relationship. Discussion of possible mediating variables reinforces the important role of perception when considering the beneficial effects that physical activity has on quality of life. From a public health perspective, understanding what may cause change in quality of life has significant implications for the design, implementation, and promotion of physical activity programs for older adults.

Self-efficacy and the progression of functional limitations and self-reported disability in older adults with knee pain

OBJECTIVES

The prospective relationships between self-efficacy beliefs, in conjunction with measures of knee pain and knee strength, and subsequent decline in both physical performance and self-reported disability among older adults with knee pain were examined.

METHODS

In this prospective epidemiological trial, 480 men and women aged 65 years and older who had knee pain on most days of the week and difficulty with daily activity were followed for 30 months.

RESULTS

There was a significant interaction of baseline self-efficacy with baseline knee strength in predicting both self-reported disability and stair climb performance. Participants who had low self-efficacy and low strength at baseline had the largest 30-month decline in these outcomes.

DISCUSSION

These data underscore the important role that self-efficacy beliefs play in understanding functional decline with chronic disease and aging. Self-efficacy beliefs appear to be most important to functional decline in older adults when they are challenged by muscular weakness in the lower extremities.

Modifiers of change in physical functioning in older adults with knee pain: the Observational Arthritis Study in Seniors (OASIS)

OBJECTIVE

To ascertain predictors of decline in physical functioning among older adults reporting knee pain.

METHODS

The Observational Arthritis Study in Seniors was a longitudinal study of 480 adults over 65 years of age. Measurements of strength, sociodemographic characteristics, disease burden (including radiographic knee osteoarthritis [OA]), self-reported disability, and functional limitations were obtained on participants at baseline and at 15 and 30 months.

RESULTS

Radiographic evidence of OA at baseline was moderately associated with an increased decline in both transfer (P = 0.06) and ambulatory-based performance tasks (P = 0.04) but not in self-reported disability. This effect disappeared after accounting for baseline levels of knee pain intensity and knee strength.

CONCLUSION

Knee pain intensity and knee strength may mediate the relationship between radiographic evidence of knee OA and change in performance. Although it is not clear whether joint disease precedes or follows a decline in muscular strength, these results may help to identify subpopulations of older persons with knee OA who may benefit from interventions aimed at slowing the progression of disability related to transfer and ambulatory-based tasks.

Perceived importance and satisfaction with physical function in patients with knee osteoarthritis

This investigation examined the determinants of satisfaction with physical function for participants in an Observational Arthritis Study in Seniors (OASIS). The sample consisted of 480 men (51%) and women (49%) over the age of 65 years who had difficulty performing activities of daily living due to knee pain. As part of baseline testing for OASIS, participants completed a measure that assessed satisfaction with function for six physical activities. After controlling for relevant covariates, scores on the satisfaction index were regressed on seven conceptually relevant predictor variables. The results revealed that satisfaction with physical function is a distinct construct from level of function, irrespective of whether the latter variable is measured objectively or subjectively. When entered into a hierarchical regression model, 6-minute walk test data accounted for 11% of the variance in satisfaction scores, whereas perceived difficulty accounted for an additional 22%. Moreover, a significant interaction term between importance and perceived difficulty revealed that patients who rated the activities as important and who had high levels of perceived difficulty had the lowest satisfaction scores. Discussion focuses on the determinants of satisfaction with physical function with emphasis on the interaction between perceived difficulty and importance.

Gender moderates the effects of exercise therapy on health-related quality of life among COPD patients

STUDY OBJECTIVES

To determine whether long-term treatment with exercise therapy results in more favorable, disease-specific, health-related quality of life (HRQL) compared with short-term treatment with exercise therapy; and to determine whether there are gender differences in disease-specific HRQL among individuals randomized into the two treatment groups.

DESIGN

Randomized clinical trial.

SETTING

Center-based exercise therapy unit at a university.

PARTICIPANTS

One hundred forty patients with COPD; 118 completed trial.

INTERVENTIONS

Short-term exercise therapy (3 months); long-term exercise therapy (18 months).

MEASUREMENTS

Chronic Disease Respiratory Questionnaire (CRQ).

RESULTS

After 3 months of treatment, there were significant improvements in all CRQ scores for men and women (p < 0.01), and for the total sample (p < 0.01). At 18 months, individuals randomized into the long-term group had significantly more favorable scores than the short-term group for dyspnea (p = 0.03), fatigue (p < 0.01), emotional function (p = 0.04), and mastery (p = 0.04). However, these effects were moderated by gender. That is, men in the long-term group reported significantly more favorable scores than men in the short-term group for dyspnea (0.04), fatigue (p < 0.001), emotional function (p = 0.02), and mastery (p = 0.02). At the 18-month assessment, there were no differences between long-term and short-term exercise therapy for women on any of the subscales of the CRQ.

CONCLUSIONS

Taken collectively, the CRQ data demonstrate that long-term exercise therapy has little added benefit for women over short-term exercise therapy; however, men derive significant benefits from extended training.

Contributions of acute bouts of vigorous physical activity to explaining diurnal variations in feeling states in active, middle-aged women

This study describes diurnal variations in feeling states in 84 women as a function of involvement in physical activity. Women completed feeling state checklists before and after bouts of vigorous physical activity that lasted a minimum of 20 min and on a stratified random-sampling protocol in response to a stimulus from an electronic pager. Participants self-reported the date, the time of day, the stimulus for responding, their current feeling states, and their ongoing activity. A total of 7,295 complete mood and activity reports were recorded in response to pager calls that were further coded into experience samplings that occurred on a nonexercise day, prior to exercise on an exercise day, and following exercise on an exercise day. Multilevel modeling analyses showed that in samplings recorded following exercise on exercise days, positive engagement, revitalization, and tranquility were elevated in comparison with predicted diurnal patterns.

Physical activity, functional limitations, and disability in older adults

OBJECTIVES

To explore initially how low levels of physical activity influence lower body functional limitations in participants of the Longitudinal Study of Aging. Changes in functional limitations are used subsequently to predict transitions in the activities of daily living/instrumental activities of daily living (ADL/IADL) disability, thus investigating a potential pathway for how physical activity may delay the onset of ADL/IADL disability and, thus, prolong independent living.

DESIGN

Analysis of a complex sample survey of US civilian, noninstitutionalized population aged 70 years and older in 1984, with repeated interviews in 1986, 1988, and 1990.

SETTING AND PARTICIPANTS

Analyses concentrated on 5151 men and women targeted for interview at all four LSOA interviews.

MEASUREMENTS

Characteristics used in analyses: gender, age, level of physical activity, comorbid conditions including the presence of hypertension, diabetes, arthritis, and atherosclerotic heart disease, levels of functional limitations, and ADL/IADL disability.

RESULTS

Transitional models provide evidence that older adults who have varying levels of disability and who report at least a minimal level of physical activity experience a slower progression in functional limitations (OR = .45, P < .001 for severe vs less severe limitations). This low level of physical activity, through its influence on changes in functional limitations, is shown to slow the progression of ADL/IADL disability.

CONCLUSIONS

Results from analyses provide supporting evidence that functional limitations can mediate the effect that physical activity has on ADL/IADL disability. These results contribute further to the increasing data that seem to suggest that physical activity can reduce the progression of disability in older adults.

An examination of theory and behavior change in randomized clinical trials

This paper underscores the important role played by theory-based mediating variables in randomized clinical trials. Indeed, it is essential that we know what mediating variables are relevant for particular outcomes in randomized clinical trials and that we design interventions to optimize change in the mediators of interest. Yet, knowledge of the pivotal mediating variables in behavior change does not imply that we know how to intervene effectively. This gap may be due to the fact that existing research typically has been designed to garner support for theory, as opposed to testing support for behavior change strategies that are based on theory. In addition, we argue that there are important mediating variables in behavior change that have not been given systematic attention in theory development. For example, behavior change must be viewed as a collaborative process, and participants' perceptions concerning the feasibility of change is important to motivational processes in randomized clinical trials. Control Clin Trials 2000;21:164S-170S

Predictors of adherence to behavior change interventions in the elderly

Considering factors at the individual, interpersonal, and environmental level may enhance adherence to interventions in the elderly. A collaborative practitioner-participant relationship is also essential. Control Clin Trials 2000;21:200S-205S

Physical function among older adults with knee pain: The role of pain coping skills

OBJECTIVE

To evaluate the association between pain coping skills and disability among older adults with knee pain.

METHODS

Baseline measures from 394 older adults with knee pain and disability who participated in a 30-month observational study were analyzed. Pain coping skills were correlated with self-reported disability and walking distance after controlling for covariates of disability.

RESULTS

Pain coping skills were significantly associated with disability (P < 0.05) and distance walked (P < 0.05). Less catastrophic thinking and prayer, greater ignoring and reinterpretation of pain sensations, and stronger perceptions of pain control were associated with less disability and better physical function.

CONCLUSION

Pain coping skills used by older adults with osteoarthritis and knee pain may play a significant role in determining disability.

Exercise and weight loss in obese older adults with knee osteoarthritis: a preliminary study

OBJECTIVE

The purposes of this pilot study were to determine if a combined dietary and exercise intervention would result in significant weight loss in older obese adults with knee osteoarthritis, and to compare the effects of exercise plus dietary therapy with exercise alone on gait, strength, knee pain, biomarkers of cartilage degradation, and physical function.

DESIGN

Single-blind, two-arm, randomized clinical trial conducted for 24 weeks.

SETTING

A university health and exercise science center.

PARTICIPANTS

Twenty-four community-dwelling obese older adults aged > or = 60 years, body mass index > or = 28, knee pain, radiographic evidence of knee osteoarthritis, and self-reported physical disability.

INTERVENTION

Randomization into two groups: exercise and diet (E&D) and exercise alone (E). Exercise consisted of a combined weight training and walking program for 1 hour three times per week. The dietary intervention included weekly sessions with a nutritionist utilizing cognitive-behavior modification to change dietary habits to reach a group goal of an average weight loss of 15 lb (6.8 kg) over 6 months.

MEASUREMENTS

All measurements were conducted at baseline and 3 and 6 months, except for synovial fluid analysis, which was obtained only at baseline and 6 months. In addition, weight was measured weekly in the E&D group. Physical disability and knee pain were measured by self-report and physical performance was measured using the 6-minute walk and stair climb tasks. Biomechanical testing included kinetic and kinematic analysis of gait and isokinetic strength testing. Synovial fluid was analyzed for levels of total proteoglycan, keratan sulfate, and interleukin-1 beta.

RESULTS

Twenty-one of the 24 participants completed the study, with one dropout in the E&D group and two in the E group. The E&D group lost a mean of 18.8 lb (8.5 kg) at 6 months compared with 4.0 lb (1.8 kg) in the E group (P = .01). Significant improvements were noted in both groups in self-reported disability and knee pain intensity and frequency as well as in physical performance measures. However, no statistical differences were found between the two groups at 6 months in knee pain scores or self-reported performance measures of physical function. There was no difference in knee strength between the groups, with both groups showing modest improvements from baseline to 6 months. At 6 months, the E&D group had a significantly greater loading rate (P = .03) and maximum braking force (P = .01) during gait. There were no significant between-group differences in the other biomechanical measures. Synovial fluid samples were obtainable at both baseline and 6 months in eight participants (four per group). The level of keratan sulfate decreased similarly in both groups from an average baseline of 96.8 +/- 37.1 to 71.5 +/- 23 ng/microg total proteoglycan. The level of IL-1 decreased from 25.3 +/- 9.8 at baseline to 8.3 +/- 6.1 pg/mL. The decrease in IL-1 correlated with the change in pain frequency (r = -0.77, P = .043).

CONCLUSIONS

Weight loss can be achieved and sustained over a 6-month period in a cohort of older obese persons with osteoarthritis of the knee through a dietary and exercise intervention. Both exercise and combined weight loss and exercise regimens lead to improvements in pain, disability, and performance. Moreover, the trends in the biomechanical data suggest that exercise combined with diet may have an additional benefit in improved gait compared with exercise alone. A larger study is indicated to determine if weight loss provides additional benefits to exercise alone in this patient population.

Contributions of acute bouts of vigorous physical activity to explaining diurnal variations in feeling states in active, middle-aged women

This study describes diurnal variations in feeling states in 84 women as a function of involvement in physical activity. Women completed feeling state checklists before and after bouts of vigorous physical activity that lasted a minimum of 20 min and on a stratified random-sampling protocol in response to a stimulus from an electronic pager. Participants self-reported the date, the time of day, the stimulus for responding, their current feeling states, and their ongoing activity. A total of 7,295 complete mood and activity reports were recorded in response to pager calls that were further coded into experience samplings that occurred on a nonexercise day, prior to exercise on an exercise day, and following exercise on an exercise day. Multilevel modeling analyses showed that in samplings recorded following exercise on exercise days, positive engagement, revitalization, and tranquility were elevated in comparison with predicted diurnal patterns.

Effects of leadership style and group dynamics on enjoyment of physical activity

PURPOSE

The primary purpose of this study was to examine the independent and combined effects of leadership style and group dynamics on the enjoyment of physical activity.

DESIGN

A completely randomized 2 x 2 factorial design was used in which the manipulation of "leadership style" (socially enriched vs. bland) was crossed with a manipulation of "group dynamics" (socially enriched vs. bland).

SETTING

The study was conducted in an aerobics studio on a university campus.

SUBJECTS

The sample included 48 male and 42 female undergraduate students who were moderately active.

INTERVENTION

Each participant was involved in a single session of step aerobics. A female graduate student provided either an enriched or bland series of interactions to manipulate leadership style, and a trained group of planted undergraduates was used to promote either an enriched or bland group environment.

MEASURES

The outcome measures of interest were enjoyment and the probability of engaging in a similar activity in the future.

RESULTS

Participants in the enriched leadership style plus enriched group dynamics condition reported higher enjoyment than did participants in the other three conditions. On average, the level of enjoyment was 22.07% higher in this condition than in the other three conditions (p < .001). The probability of future involvement was 13.93% higher for participants in the enriched group environment, irrespective of leadership style (p < .03).

CONCLUSIONS

Enjoyment during physical activity is optimized when a positive and supportive leadership style is coupled with an enriched and supportive group environment. Future research is required to extend these findings to other activities and populations.

Effects of mental stress on brachial artery flow-mediated vasodilation in healthy normal individuals

BACKGROUND

Mental stress is associated with increased risk for cardiovascular events, possibly because of acute increases in endogenous catecholamines. Recently, brachial artery flow-mediated vasodilation has been used for noninvasive assessment of macrovascular endothelial function. The effect of mental stress and its associated changes in sympathetic activation on brachial artery endothelium-dependent vasomotor tone in vivo remains unknown.

METHODS AND RESULTS

Two-dimensional ultrasound was used to measure brachial artery flow-mediated vasodilation before and after mental stress (provoked by a standard arithmetic challenge) in 21 healthy individuals (10 men, 11 women; average age 23.5 years). The flow stimulus resulted from a 3-minute cuff occlusion of distal forearm blood flow, causing distal hyperemia and a transient 2- to 3-fold increase in brachial artery blood flow on cuff release. During mental stress, heart rate increased on average by 29.6% and blood pressure increased on average by 17.9%. The sympathetic stimulus resulted in a 64% average increase in flow-mediated vasodilator response (P <.001). The enhanced vasodilator response during mental stress was similar for men and women.

CONCLUSIONS

Mental stress can have marked effects on endothelium-dependent, flow-mediated vasodilation in healthy, normal individuals. Similar studies in individuals with impaired endothelial function may further our understanding of the role of mental stress in the development of cardiovascular events.

Evaluating and understanding performance testing in COPD patients

PURPOSE

There is increasing interest in the use of performance tests to assess physical function among patients with debilitating diseases. The purpose of this study was to describe the measurement properties of a performance test battery used in the Reconditioning Exercise and Chronic Obstructive Pulmonary Disease Trial and to explore how well-selected physiologic and psychosocial measures explained test performance.

METHODS

To assess test-retest reliability of the performance tests, older patients with chronic obstructive pulmonary disease (n = 30) completed, on two different occasions, a 6-minute walk for distance, a timed stair climb, and a timed elevated-arm task. In addition, stepwise regression analyses were conducted on a larger sample (n = 209) to examine how effective conceptually relevant physiologic and psychosocial variables were at explaining variation in task performance.

RESULTS

Results showed that all three performance tasks had good test-retest reliability (all coefficients > 0.80) and shared variance in expected directions with VO2peak, forced expiratory volume in 1 second (FEV1), and self-reported disability. Regression analyses suggest that VO2peak, FEV1, self-efficacy, and self-reported disability are important variables to consider in attempts to understand performance-related disability in patients with chronic obstructive pulmonary disease (COPD).

CONCLUSIONS

The physical performance test battery appears to be a reliable means of assessing physical functioning in older patients with COPD. Furthermore, findings support the important role that VO2peak plays in task performance and suggest that patients' perceptions should be given careful consideration when attempting to understand physical decline in clinical settings.

A home-based maintenance exercise program after center-based cardiac rehabilitation: effects on blood lipids, body composition, and functional capacity

BACKGROUND

Previous research indicates that patients exiting a 12-week cardiac rehabilitation program (CRP) have difficulty maintaining an adequate exercise program. Thus, the authors' purpose was to determine if a home-based exercise program would enable patients to maintain/improve their blood lipids, body composition, and functional capacity after exiting the CRP.

METHODS

Thirty-one patients exiting an initial 12-week CRP were assigned randomly to the home-based (HB) intervention or the standard care (SC) condition. After one home visit, the HB participants (n = 16) were contacted by telephone every other week by CRP staff and completed and returned weekly exercise logs. The SC participants (n = 15) had no contact with the CRP other than to schedule follow-up tests. A third group (n = 17), randomly selected from patients that elected to remain in the center-based CRP (CB) for the same duration, also were examined. All groups underwent exercise testing, fasting blood lipid analysis, and body composition assessment before starting CRP (0M), after 3 months (3M) in a standard CRP, and after 9 months (12M) in either HB, SC, or CB condition (12 months after starting CRP).

RESULTS

Analysis of variance indicated that there were significant increases in metabolic equivalents and high-density lipoprotein, in all three groups, over time. However, analysis of covariance revealed no significant differences between the HB, SC, and CB groups at 12M for any variable.

CONCLUSIONS

These data indicate that the HB program was as effective as the CB program at improving/maintaining functional capacity, blood lipids, and body weight/composition. The similar success of the SC group is likely due to their prior experience in CRP and knowledge of follow-up testing. Home-based maintenance program could be offered as a low-cost alternative to CB programs.

Exercise rehabilitation and chronic obstructive pulmonary disease stage

To determine the extent to which patients with Stage I COPD experience improvements in physical performance and quality of life as a result of exercise training, and to compare these improvements with those seen in Stage I and II patients, 151 patients with COPD underwent a 12-wk exercise program. Outcomes were measured at baseline and follow-up. Physical performance was evaluated by means of a 6-min walk, treadmill time, an overhead task, and a stair climb. General health-related quality of life was assessed in terms of the domains of Social Function, Health Perceptions, and Life Satisfaction. Disease-specific health-related quality of life was assessed with the Chronic Respiratory Disease Questionnaire (CRQ). Six-minute walk distance increased significantly in Stage I (200.5 ft [95% CI: 165.4, 235.7]), Stage II (238.3 ft [143.3, 333.3]), and Stage III (112.1 ft [34.6, 189.6]) participants. Treadmill time increased significantly in Stage I (0.42 min [0.20, 0.64]) and Stage II (0.64 min [0.14, 1.4]) participants. Time to complete the overhead task decreased significantly in Stage I (0.91 s [1.72, 0. 11]) and Stage II (1.39 s [2.66, 0.13]) participants. None of the measures of general health-related quality of life improved in any of the three groups. Participants in Stages I, II, and III all experienced improvements in the CRQ domains of dyspnea (0.72 [0.53, 0.91], 0.47 [0.02, 0.91], and 0.46 [0.05, 0.87], respectively) and fatigue (0.49 [0.33, 0.66], 0.54 [0.20, 0.87], and 0.55 [0.05, 1.05], respectively). These results suggest that all patients with COPD will benefit from exercise rehabilitation. Berry MJ, Rejeski WJ, Adair NE, Zaccaro D. Exercise rehabilitation and chronic obstructive pulmonary disease stage.

The relationships among pulmonary function, aerobic fitness, and cognitive functioning in older COPD patients

STUDY OBJECTIVES

To study the predictive relationships among age, pulmonary function, aerobic fitness, and cognition in people with COPD.

DESIGN

Observational study conducted during baseline testing with COPD patients who volunteered to participate in an exercise intervention.

PARTICIPANTS

Older adults (age, 56 to 80 years) with COPD.

MEASUREMENTS AND RESULTS

Age, depression, education level, aerobic fitness, blood oxygen saturation levels, and pulmonary function were assessed. Participants were randomly assigned to take cognitive tests of (1) fluid intelligence, (2) processing speed and working memory span, or (3) processing speed and inhibition. After controlling for education and depression (F(2,57) = 7.43; r(2) = 0. 21), performance on the 6-min walk (F(1,56) = 15.27; r(2) = 0.17) and age (F(1,55) = 7.52; r(2) = 0.08) were significant predictors of fluid intelligence. On the speed-of-processing task, performance on the 6-min walk (F(1,30) = 8.17; r(2) = 0.20), maximum voluntary ventilation (F(1,29) = 5.81; r(2) = 0.16), and age (F(1,28) = 5.26; r(2) = 0.10) were significant predictors. FVC was a significant predictor (F(1,25) = 6.37; r(2) = 0.18) of working memory span. The ability to inhibit a response was not significantly predicted by any of the variables assessed.

CONCLUSIONS

In an older COPD sample, age, aerobic fitness, and pulmonary function are predictive of cognitive performance on various tasks. In particular, age and aerobic fitness are predictive of speed of processing, which is a cognitive variable that may itself underlie performance on a majority of cognitive tasks.

Validation of the PASE in older adults with knee pain and physical disability

PURPOSE

To examine the validity of the Physical Activity Scale for the Elderly (PASE) among individuals with disability.

METHODS

A sample of 471 participants (mean age = 71.36) in an epidemiological study of chronic knee pain completed the PASE and self-report measures of knee pain, perceived physical function, satisfaction with physical function, and importance of physical function. A 6-min walk test and an isokinetic assessment of knee strength were also administered.

RESULTS

PASE scores were significantly correlated in expected directions with performance on the 6-min walk, knee strength, frequency of knee pain during transfer, and perceived difficulty with physical functioning. Gender and age were identified as significant moderators of PASE scores and the scale's construct validity was supported by testing a conceptually driven hypothesis regarding patterns of physical activity.

CONCLUSIONS

These results support the PASE's validity for the assessment of physical activity among older adults with pain and disability.

Physical activity interventions targeting older adults. A critical review and recommendations

BACKGROUND

Although many of the chronic conditions plaguing older populations are preventable through appropriate lifestyle interventions such as regular physical activity, persons in this age group represent the most sedentary segment of the adult population. The purpose of the current paper was to provide a critical selected review of the scientific literature focusing on interventions to promote physical activity among older adults.

METHODS

Comprehensive computerized searches of the recent English language literature aimed at physical activity intervention in adults aged 50 years and older, supplemented with visual scans of several journal on aging, were undertaken. Articles were considered to be relevant for the current review if they were community-based, employed a randomized design or a quasi-experimental design with an appropriate comparison group, and included information on intervention participation rates, pre- and post-intervention physical activity levels, and/or pre/post changes in relevant physical performance measures.

RESULTS

Twenty-nine studies were identified that fit the stated criteria. Among the strengths of the studies reviewed were reasonable physical activity participation rates and relatively long study durations. Among the weaknesses of the literature reviewed were the relative lack of specific behavioral or program-based strategies aimed at promoting physical activity participation, as well as the dearth of studies aimed at replication, generalizability of interventions to important subgroups, implementation, and cost-effectiveness evaluation.

CONCLUSIONS

Recommendations for future scientific endeavors targeting older adults are discussed.

Overview of the Activity Counseling Trial (ACT) intervention for promoting physical activity in primary health care settings. Activity Counseling Trial Research Group

Counseling by health care providers has the potential to increase physical activity in sedentary patients, yet few studies have tested interventions for physical activity counseling delivered in health care settings. The Activity Counseling Trial (ACT) is a 5-yr randomized clinical trial to evaluate the efficacy of two primary care, practice-based physical activity behavioral interventions relative to a standard care control condition. A total of 874 sedentary men and women, 35-75 yr of age, have been recruited from primary care physician offices at three clinical centers for 2 yr of participation. They were randomly assigned to one of three experimental conditions that vary, in a hierarchical fashion, by level of counseling intensity and resource requirements. The interventions, which are based on social cognitive theory and the transtheoretical model, are designed to alter empirically based psychosocial mediators that are known to be associated with physical activity. The present paper describes the theoretical background of the intervention, the intervention methods, and intervention training and quality control procedures.

Treating disability in knee osteoarthritis with exercise therapy: a central role for self-efficacy and pain

OBJECTIVE

To examine the effects of aerobic and resistance exercise on self-efficacy beliefs in older adults with knee osteoarthritis (OA) and to determine whether self-efficacy and knee pain mediated the effects of the treatments on stair time performance and health perceptions.

METHODS

Measures of self-efficacy, knee pain, stair climbing performance, and health perceptions were collected prior to randomization and again at an 18-month followup in older adults with knee OA who were assigned to 1 of 3 treatment conditions: aerobic exercise, resistance training, or health education control. All analyses were conducted on the intention-to-treat principle.

RESULTS

Both exercise treatments increased self-efficacy for stair climbing in comparison to the health education control group. Both knee pain and self-efficacy mediated the effect of the treatments on stair climb time, whereas only knee pain mediated health perceptions.

CONCLUSIONS

The findings suggest that control beliefs and changes in physical symptoms such as knee pain are important outcomes in physical activity programs with patients who have OA of the knee. Moreover, these variables mediate the effects that such programs have on disability and health perceptions.

Compliance to exercise therapy in older participants with knee osteoarthritis: implications for treating disability

This investigation examined predictors of compliance with exercise therapy in a clinical trial involving older adults with knee osteoarthritis (OA). The study sample was partitioned into tertiles by level of compliance to determine its effect on several clinical outcome measures in the trial (i.e., knee pain, difficulty with activities of daily living, and performance-related disability). The participants (N = 439) first completed all baseline assessments and were then randomly assigned to one of three treatment conditions: health education control, aerobic exercise, or resistance exercise. The two exercise treatments involved a 3-month center-based phase and a 15-month home-based phase. Variables in five categories (i.e., demographic, fitness, health-related quality of life, performance-related disability, and prior exercise behavior) were entered as predictors of attendance and time spent exercising during each session for three different periods of time across the course of the study. Results of these analyses revealed that it was possible to explain more variance for time spent exercising (approximately 40%) during the first 3 months than for attendance (approximately 10%). Furthermore, once participants completed the first 3 months of their training, prior behavior was the strongest predictor of exercise compliance. In most cases, the regression models accounted anywhere from 26 to 46% of the variance in attendance or time spent exercising (7 of the 8 P values < 0.01). In general, demographic, fitness, psychosocial, and disability-related measures did not predict compliance with any consistency across the various phases of the trial. Analysis of the dose-response data suggest that, in the use of aerobic exercise to deter disability in older people with knee OA, consideration should be given to prescribing frequent bouts of activity (at least 3 times each week) of moderate duration (approximately 35 min).

A naturalistic study of the impact of acute physical activity on feeling states and affect in women

This field study used experience sampling procedures to examine the relationship of feeling states and affect to acute bouts of physical activity in women. Participants (N = 86) completed brief affect and feeling state measures (a) in response to random stratified pager tones and (b) before and after acute bouts of vigorous physical activity for 6 weeks. Analysis of averaged difference scores revealed that acute vigorous physical activity was associated with significant improvements in affect and feeling states, particularly in feelings of revitalization. Moreover, within-subject analyses indicated that the effects were moderated by preactivity scores, with the greatest improvements seen when women felt worst before activity.

A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST)

OBJECTIVE

To determine the effects of structured exercise programs on self-reported disability in older adults with knee osteoarthritis.

SETTING AND DESIGN

A randomized, single-blind clinical trial lasting 18 months conducted at 2 academic medical centers.

PARTICIPANTS

A total of 439 community-dwelling adults, aged 60 years or older, with radiographically evident knee osteoarthritis, pain, and self-reported physical disability.

INTERVENTIONS

An aerobic exercise program, a resistance exercise program, and a health education program.

MAIN OUTCOME MEASURES

The primary outcome was self-reported disability score (range, 1-5). The secondary outcomes were knee pain score (range, 1-6), performance measures of physical function, x-ray score, aerobic capacity, and knee muscle strength.

RESULTS

A total of 365 (83%) participants completed the trial. Overall compliance with the exercise prescription was 68% in the aerobic training group and 70% in the resistance training group. Postrandomization, participants in the aerobic exercise group had a 10% lower adjusted mean (+/- SE) score on the physical disability questionnaire (1.71 +/- 0.03 vs 1.90 +/- 0.04 units; P<.001), a 12% lower score on the knee pain questionnaire (2.1 +/- 0.05 vs 2.4 +/- 0.05 units; P=.001), and performed better (mean [+/- SE]) on the 6-minute walk test (1507 +/- 16 vs 1349 +/- 16 ft; P<.001), mean (+/-SE) time to climb and descend stairs (12.7 +/- 0.4 vs 13.9 +/- 0.4 seconds; P=.05), time to lift and carry 10 pounds (9.1 +/- 0.2 vs 10.0 +/- 0.1 seconds; P<.001), and mean (+/-SE) time to get in and out of a car (8.7 +/- 0.3 vs 10.6 +/- 0.3 seconds; P<.001) than the health education group. The resistance exercise group had an 8% lower score on the physical disability questionnaire (1.74 +/- 0.04 vs 1.90 +/- 0.03 units; P=.003), 8% lower pain score (2.2 +/- 0.06 vs 2.4 +/- 0.05 units; P=.02), greater distance on the 6-minute walk (1406 +/- 17 vs 1349 +/- 16 ft; P=.02), faster times on the lifting and carrying task (9.3 +/- 0.1 vs 10.0 +/- 0.16 seconds; P=.001), and the car task (9.0 +/- 0.3 vs 10.6 +/- 0.3 seconds; P=.003) than the health education group. There were no differences in x-ray scores between either exercise group and the health education group.

CONCLUSIONS

Older disabled persons with osteoarthritis of the knee had modest improvements in measures of disability, physical performance, and pain from participating in either an aerobic or a resistance exercise program. These data suggest that exercise should be prescribed as part of the treatment for knee osteoarthritis.

Comparison of standard- and extended-length participation in cardiac rehabilitation on body composition, functional capacity, and blood lipids

Participation in a standard-length outpatient cardiac rehabilitation program (CRP) for 3 months is known to result in positive changes in body composition, functional capacity, and blood lipids in patients with coronary artery disease. However, there has been little attempt to compare patients who remain active in a formal CRP for an extended length of >1 year with patients who exit after a standard length of 3 months. Consequently, 50 patients underwent a series of tests including a maximal graded exercise treadmill test, assessment of body composition, and fasting blood lipid analysis, at entry to CRP and after a follow-up period that ranged from 1 to 5 years. All patients participated in a standard multidisciplinary cardiac rehabilitation program for 3 months. Twenty-five patients discontinued participation after 3 months and received no other contact from the program staff until follow-up, whereas 25 patients remained active in the program until follow-up. After statistically adjusting for baseline differences between the groups, significant differences were observed between the extended- and standard-length groups at follow-up for body weight (177 vs 183 lbs), percent fat (22% vs 24%), METS (10.5 vs 8.4), high-density lipoprotein level cholesterol (44 vs 39 mg/dl), total cholesterol/high-density lipoprotein ratio (5.2 vs 6.1), and triglycerides (134 vs 204 mg/dl), respectively. No significant differences in the adjusted means were observed between the groups at follow-up for total cholesterol (209 vs 219 mg/dl) and low-density lipoprotein cholesterol (136 vs 138 mg/dl). Data from this study demonstrate the efficacy of extended participation in CRP on body composition, functional capacity, and blood lipids. Greater efforts need to be directed at retaining patients in low-cost, center-based maintenance programs and at extending monitoring of patients exiting standard length CRPs.

A naturalistic study of the impact of acute physical activity on feeling states and affect in women

This field study used experience sampling procedures to examine the relationship of feeling states and affect to acute bouts of physical activity in women. Participants (N = 86) completed brief affect and feeling state measures (a) in response to random stratified pager tones and (b) before and after acute bouts of vigorous physical activity for 6 weeks. Analysis of averaged difference scores revealed that acute vigorous physical activity was associated with significant improvements in affect and feeling states, particularly in feelings of revitalization. Moreover, within-subject analyses indicated that the effects were moderated by preactivity scores, with the greatest improvements seen when women felt worst before activity.

Estimation of VO2 in older individuals with osteoarthritis of the knee and cardiovascular disease

The American College of Sports Medicine (ACSM) equation for estimating oxygen consumption (VO2) is often inappropriately applied to non-steady-state treadmill exercise. Therefore, it was the purpose of this investigation to develop an equation to estimate VO2 that could be applied to non-steady-state treadmill exercise in a population of patients with osteoarthritis of the knee, and to assess the generalizability of this equation for estimating VO2peak in patients with cardiovascular disease. Subjects for the investigation were 414 participants in the Fitness and Arthritis in Seniors Trial (FAST), and 362 patients with cardiovascular disease. Results from the FAST subjects showed that the ACSM equation was inappropriate for estimating VO2 during non-steady-state incremental treadmill walking. We developed the following equation (FAST) using speed and the interaction between speed and grade as the predictor variables during treadmill walking: VO2(ml.kg-1.min-1) = 0.0698 x speed(m.min-1) + 0.8147 x grade(%) x speed(m.min-1) + 7.533 ml.kg-1.min-1 The generalizability of the FAST equation for estimating VO2peak was evaluated in the patients with cardiovascular disease. The measured VO2peak of these patients was 23.7 +/- 0.3 ml.kg-1.min-1, whereas the VO2peak values estimated from the FAST equation and the ACSM equation were 24.1 +/- 0.3 and 33.2 +/- 0.5 ml.kg-1.min-1, respectively. No significant differences were found between the measured VO2peak and that estimated from the FAST equation. The VO2peak estimated from the ACSM equation was significantly greater than the measured VO2peak. These results suggest it is more appropriate to use the FAST equation rather than the ACSM equation to estimate VO2 in older patients with either osteoarthritis of the knee or cardiovascular disease.

Self-efficacy and pain in disability with osteoarthritis of the knee

This study examined the relationship between self-efficacy beliefs and pain during the performance of stair climbing and lifting/carrying tasks on speed of movement, ratings of task difficulty, and perceived task ability in a group of patients with osteoarthritis (OA) of the knee. Seventy-nine patients with knee OA completed the tasks in a controlled laboratory setting. Before completing each task, patients' self-efficacy was assessed; following task performance they rated (a) the most intense knee pain experienced, (b) the difficulty of the task, and (c) their perceived ability as they performed each task. Results demonstrated that, even after controlling for physical function, self-efficacy, and knee pain during performance, each contributed significantly to understanding either speed of movement or self-reported ratings of task difficulty and perceived ability.

Effects of baseline responses, in-task feelings, and duration of activity on exercise-induced feeling states in women

This study investigated the hypothesis that the effects of acute aerobic exercise on feeling states may be influenced by the objective dose of activity, subjective responses during exercise, and preexisting levels of feeling states. College-age women (N = 80) completed baseline measures and were then randomly assigned to 1 of 4 conditions: attention control for 10 min, or exercise for 10 min, 25 min, or 40 min. Levels of exertion and affect were assessed during exercise, and posttesting occurred 20 min following activity. Exercise enhanced revitalization in comparison with the control condition; however, this effect occurred only for participants scoring low to moderate on the pretest. In addition, in-task feeling states predicted postexercise revitalization even after we controlled for the treatment, the pretest, and the Pretest x Treatment interaction.

Assessing performance-related disability in patients with knee osteoarthritis

This investigation describes the development and validation of a test battery for evaluating physical activity restrictions (PAR) in patients with knee osteoarthritis (OA). The tasks on the final version of the PAR include (a) a 6-min walk; (b) a stair climb; (c) a lifting and carrying task; and (d) getting into and out of a car. Data from patients with knee OA revealed that the four tasks loaded highly on a single unrotated principal component yielding an alpha internal consistency reliability of 0.92. These data suggest that investigators may choose to use an aggregate score and/or responses from individual tasks. Two week test-retest reliabilities for the four tasks were all in excess of 0.85 and there was support for their concurrent and convergent validity. Specifically, performance on the tasks correlated with time on treadmill, difficulty with self-reported ADLs, and ratings of difficulty following the performance of each task. Additional research is needed on the predictive validity of the measure and its sensitivity to change.

Effects of baseline responses, in-task feelings, and duration of activity on exercise-induced feeling states in women

This study investigated the hypothesis that the effects of acute aerobic exercise on feeling states may be influenced by the objective dose of activity, subjective responses during exercise, and preexisting levels of feeling states. College-age women (N = 80) completed baseline measures and were then randomly assigned to 1 of 4 conditions: attention control for 10 min, or exercise for 10 min, 25 min, or 40 min. Levels of exertion and affect were assessed during exercise, and posttesting occurred 20 min following activity. Exercise enhanced revitalization in comparison with the control condition; however, this effect occurred only for participants scoring low to moderate on the pretest. In addition, in-task feeling states predicted postexercise revitalization even after we controlled for the treatment, the pretest, and the Pretest x Treatment interaction.

Moderate exercise training and natural killer cell cytotoxic activity in breast cancer patients

Sixteen female breast cancer patients who had been diagnosed (3.0 +/- 1.2 years previous to the study) and undergone surgery, chemotherapy, and/or radiation treatment were randomly assigned to exercise and nonexercise groups. Pre- and post-study measurements were taken for aerobic performance, leg strength, and concentrations of circulating lymphocyte subsets and natural killer cell cytotoxic activity (NKCA). Exercise training consisted of 60 minutes of supervised weight training and aerobic activity three times each week for eight weeks. Although subjects in the exercise groups demonstrated some modest improvement in the various aerobic and strength tests, NKCA and concentrations of circulating T and NK cells were not significantly altered relative to the nonexercise group. This study suggests that moderate exercise over an eight-week period has no significant effect on the function of in vitro natural killer cells in breast cancer patients.

The evaluation of pain in patients with knee osteoarthritis: the knee pain scale

OBJECTIVE

To develop and validate a knee pain scale (KPS) for use with osteoarthritis (OA) of the knee.

METHODS

Patients with documented evidence of knee OA completed the KPS and a test battery including measures of physical functioning, physical performance, and depression. Analyses were conducted to confirm the 4-factor structure of the measure, determine alpha reliabilities, assess the test-retest reliability, and examine the construct validity of the KPS.

RESULTS

Confirmatory factor analysis revealed that the KPS has 4 subscales, including frequency and intensity of pain experienced during both ambulation/climbing and transfer activities. All reliabilities were in excess of 0.80 and the subscales of the KPS shared expected variance with both self-reported and objective indices of dysfunction.

CONCLUSION

The KPS has good psychometric properties for assessing pain experienced in conjunction with the performance of activities of daily living. Although at present it is a research tool, with further study it should prove valuable in clinical practice as well.

Knee osteoarthritis and health-related quality of life

This section of the symposium addresses the definition, measurement, and relevance of health-related quality of life (HRQL) to osteoarthritis (OA) of the knee. Emphasis is placed on the multidimensional nature of HRQL and the fact that these measures can be used as either outcome or process variables. Clearly, HRQL has been accepted as an appropriate measure of treatment efficacy (an outcome measure) in most clinical research, augmenting the more traditional measures of morbidity and mortality. However, as this paper demonstrates, HRQL measures constitute important process variables in understanding disability and related concepts that are critical in designing effective therapies for treating knee OA.