Factors that modify the association between knee pain and mobility limitation in older women: the Women's Health and Aging Study

Predictors of 6-minute walk test results in lean, obese and morbidly obese women

The aim of this study was first, to assess the presence of medical conditions that might interfere with walking; second, to assess the differences in walking capacity, perceived exertion and physical complaints between lean, obese and morbidly obese women; and third, to identify anthropometric, physical fitness and physical activity variables that contribute to the variability in the distance achieved during a 6-minute walk test in lean and obese women. A total of 85 overweight and obese females (18-65 years, body mass index (BMI) > or = 27.5 kg m(-2)), 133 morbidly obese females (BMI > or = 35 kg m-2) and 82 age-matched sedentary lean female volunteers (BMI < or = 26 kg m(-2)) were recruited. Patients suffering from severe musculoskeletal and cardiopulmonary disease were excluded from the study. Prior to the test, conditions that might interfere with walking and hours of TV watching were asked for. Physical activity pattern was assessed using the Baecke questionnaire. Weight, height, body composition (bioelectrical impedance method), isokinetic concentric quadriceps strength (Cybex) and peak oxygen uptake (peakVO2_bicycle ergometer) were measured. A 6-minute walk test was performed and heart rate, walking distance, Borg rating scale of perceived exertion (RPE) and physical complaints at the end of the test were recorded. In obese and particularly in morbidly obese women suffering from skin friction, urinary stress incontinence, varicose veins, foot static problems and pain, wearing insoles, suffering from knee pain, low back pain or hip arthritis were significantly more prevalent than in lean women (P < 0.05). Morbidly obese women (BMI > 35 kg m(-2)N = 133) walked significantly slower (5.4 km h(-1)) than obese (5.9 km h(-1)) and lean women (7.2 km h(-1), P < 0.05), were more exerted (RPE 13.3, 12.8 and 12.4, respectively, P < 0.05) and complained more frequently of dyspnea (9.1%, 4.7% and 0% resp., P < 0.05) and musculoskeletal pain (34.9%, 17.7% and 11.4% resp., P < 0.05) at the end of the walk. In a multiple regression analysis, 75% of the variance in walking distance could be explained by BMI, peakVO2, quadriceps muscle strength age, and hours TV watching or sports participation. These data suggest that in contrast with lean women, walking ability of obese women is hampered not only by overweight, reduced aerobic capacity and a sedentary life style, but also by perceived discomfort and pain. Advice or programs aimed at increasing walking for exercise also need to address the conditions that interfere with walking, as well as perceived symptoms and walking difficulties in order to improve participation and compliance.

Sit-to-stand performance depends on sensation, speed, balance, and psychological status in addition to strength in older people

BACKGROUND

Sit-to-stand (STS) performance is often used as a measure of lower-limb strength in older people and those with significant weakness. However, the findings of recent studies suggest that performance in this test is also influenced by factors associated with balance and mobility. We conducted a study to determine whether sensorimotor, balance, and psychological factors in addition to lower-limb strength predict sit-to-stand performance in older people.

METHODS

Six hundred and sixty nine community-dwelling men and women aged 75-93 years (mean age 78.9, SD = 4.1) underwent quantitative tests of strength, vision, peripheral sensation, reaction time, balance, health status, and sit-to-stand performance.

RESULTS

Many physiological and psychological factors were significantly associated with sit-to-stand times in univariate analyses. Multiple regression analysis revealed that visual contrast sensitivity, lower limb proprioception, peripheral tactile sensitivity, reaction time involving a foot-press response, sway with eyes open on a foam rubber mat, body weight, and scores on the Short-Form 12 Health Status Questionnaire pain, anxiety, and vitality scales in addition to knee extension, knee flexion, and ankle dorsiflexion strength were significant and independent predictors of STS performance. Of these measures, quadriceps strength had the highest beta weight, indicating it was the most important variable in explaining the variance in STS times. However, the remaining measures accounted for more than half the explained variance in STS times. The final regression model explained 34.9% of the variance in STS times (multiple R =.59).

CONCLUSIONS

The findings indicate that, in community-dwelling older people, STS performance is influenced by multiple physiological and psychological processes and represents a particular transfer skill, rather than a proxy measure of lower limb strength.

Physiologic, psychologic, and health predictors of 6-minute walk performance in older people

OBJECTIVE

To determine the extent to which physiologic, psychologic, and health-related factors predict 6-minute walk distance (6MWD) in older people.

DESIGN

Cross-sectional study.

SETTING

Retirement villages.

PARTICIPANTS

A total of 515 people between the ages of 62 and 95 years (mean +/- standard deviation, 79.5+/-6.4y) residing in retirement villages in Australia.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Quantitative tests of vision, strength, peripheral sensation, reaction time, and balance and short Mini-Mental State Examination, Geriatric Depression Scale, Positive and Negative Affect Schedule (PANAS), Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and 6MWD.

RESULTS

All physiologic, psychologic, and health scores were significantly associated with 6MWD. Multiple regression analysis revealed that 10 factors (visual contrast sensitivity, lower-limb strength, simple reaction time, postural sway, maximal balance range, PANAS positive scale score, SF-36 pain score, number of medications used, SF-36 general health subscale score, age) were significant and independent predictors of 6MWD performance. Of these measures, strength, maximal balance range, medication use, and age explained the largest proportions of the variance in 6MWD. The final regression model explained over half (52.5%) of the variance in 6MWD (multiple r=.72).

CONCLUSIONS

In older people, 6MWD depends on multiple physiologic, psychologic, and health factors. Thus, 6MWD appears to provide a measure of overall mobility and physical functioning in this population group rather than a specific measure of cardiovascular fitness.

Differences in Pain-related Characteristics Among Younger and Older Veterans Receiving Primary Care: Table 1

OBJECTIVES

To characterize the nature of pain complaints among younger and older veterans receiving primary care, and to determine whether characteristics of pain vary as a function of age.

METHODS

Primary care patients at a Veterans Affairs medical center were screened for pain prior to a routine office visit, and those who endorsed a concern about pain were given a self-administered questionnaire that inquired about specific characteristics of their pain including site, duration, frequency, and average intensity of the pain.

RESULTS

Over a 7-month period, 1,290 patients were screened; 641 (50%) reported a concern about pain, and of these, 516 (82%) completed the pain survey. Among younger (age <65 years, N = 191) and older (age > or =65 years, N = 325) respondents, the mean number of sites causing pain was similar (3.6 vs 3.3). Back pain was the most frequently reported site of pain causing the most discomfort among younger (vs older) respondents (31.9% vs 17.8%), whereas older (vs younger) respondents most often endorsed leg pain (32.3% vs 19.9%). The mean duration of pain was not significantly different between older and younger (10.7 vs 10.1 years) respondents; but older (vs younger) respondents were more likely to report constant pain (63.7% vs 46.9%). Using a 0 to 10 numeric rating scale, pain intensity scores were higher among younger (vs older) respondents (5.3 vs 4.3). Rates of prescription pain medication use were not significantly different (52.4% vs 48.0%). Compensation for pain-related disability was more common among younger (vs older) respondents (40.4% vs 19.4%).

CONCLUSION

Concerns about pain are common among veterans receiving primary care. Characteristics of pain, including site, frequency, and intensity, varied as a function of age. Future studies are needed to confirm these findings in other primary care populations and to determine reasons for these differences.

Musculoskeletal pain and risk for falls in older disabled women living in the community

OBJECTIVES

To determine whether musculoskeletal pain increased risk for falls in older women with disabilities.

DESIGN

Prospective population-based cohort study.

SETTING

The city and county of the eastern area of Baltimore.

PARTICIPANTS

One thousand two women aged 65 and older, participants in the Women's Health and Aging Study, representing the one-third of older women who were living at home with disabilities, followed semiannually for 3 years beginning in 1991.

MEASUREMENTS

Pain was categorized into four groups according to severity and location. Widespread pain was defined as pain in the upper and lower extremities and in the axial skeletal region, with moderate to severe pain in at least one region (> or = 4 on a 10-point numeric rating scale, 10 = excruciating pain). Moderate to severe lower extremity pain that did not meet criteria for widespread pain was the next category. The reference category was no pain or mild pain in one site. The additional category of "other pain" was pain that did not fit into the other three groups. The occurrence of falls and fall-related injuries were assessed at each interview.

RESULTS

Of the 940 women who participated in at least one follow-up examination, 39% fell in first year; of the survivors, 36% fell in Year 2, and 39% in Year 3. After adjusting for several major risk factors for falls, women with widespread pain had an increased likelihood of falling during follow-up (adjusted odds ratio (AOR) = 1.66, 95% confidence interval (CI) = 1.25-2.21) compared with those with no or mild pain in only one musculoskeletal site. Women who had other musculoskeletal pain but not widespread pain or lower extremity pain also had an increased risk of falls (AOR = 1.36, 95% CI = 1.02-1.82). Among women with musculoskeletal pain, risk for falls was lower in those who used daily analgesic medication. Risk for recurrent falls and self-reported fractures due to falls was also elevated in women with musculoskeletal pain, most consistently in women with widespread pain.

CONCLUSIONS

Musculoskeletal pain, particularly widespread pain, is a substantial risk factor for falls in older women with disabilities. These findings add an important dimension to our understanding of the multifactorial processes leading to falls in older persons.

Impact of pain on disability among older Mexican Americans

BACKGROUND

Joint pain is a very common complaint among elderly persons and may lead to functional disability. The purpose of this study is to estimate the prevalence of self-reported pain on weight bearing and its impact on the 2-year incidence of limitation in lower-body activities of daily living (ADL) in initially nondisabled Mexican American elderly subjects.

METHODS

We studied a probability sample of 2167 noninstitutionalized Mexican American men and women aged 65 or older residing in five Southwestern states. Subjects were asked about pain on weight bearing, ADL, depressive symptomatology, and the presence of chronic diseases. The body mass index was computed using measured height and weight. Finally, a three-task (tandem balance, 8-foot walk, and repeated chair stands), performance-based, lower-body function test was performed.

RESULTS

The overall prevalence of pain on weight bearing in the sample was 31.9%, with 37.7% for women versus 24.0% for men (p <.001). The most prevalent sites of pain were knees (14.7%), followed by ankle/feet (12.1%). In a logistic regression analysis, pain was a significant independent predictor of subsequent disability and of the inability to perform tandem balance, 8-foot walk, and repeated chair stands.

CONCLUSIONS

Pain on weight bearing is prevalent among older Mexican Americans and is a major independent risk factor for subsequent disability.

Anaerobic glycolysis in normal human erythrocytes incubated in vitro with sodium salicylate

1. Some effects of sodium salicylate upon anaerobic glycolysis have been studied in normal human erythrocytes incubated for up to 6 h at 37 degrees C in autologous sera. 2. Both glucose consumption and lactate production were stimulated by concentrations of salicylate up to 60 mmol/l but at the highest concentration used (90 mmol/l) an initial stimulus was followed by inhibition of glycolysis. 3. Losses occurred of adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and adenosine 5'-phosphate(AMP)at higher concentrations of salicylate and there was a concomitant increase of inorganic phosphate. 4. Other phosphate esters underwent concentration changes at higher concentrations of salicylate that reflected inadequate concentrations of ATP for glycolysis. 5. The rates of sodium efflux from, and potassium influx into, erythrocytes were unaffected by the presence of salicylate at concentrations sufficient to stimulate glycolysis.