Obesity Research & Clinical Practice (2007) 1, 39—51
ORIGINAL ARTICLES
Disability in obese elderly women: Lower limb strength and recreational physical activity Yves Rolland a,b,d,∗, Val´ erie Lauwers-Cances b,c, Christelle Cristini c, H´ el` ene Grandjean b, William A. Banks d, John E. Morley d, Bruno Vellas a,b a
Department of Internal Medicine and Geriatrics, CHU La-Grave-Casselardit, Toulouse, 170 Casselardit Avenue, 31300 Toulouse, France b Inserm 558, IFR 126, Faculty of Medicine, Toulouse, France c Laboratory of Epidemiology and Community Health, Faculty of Medicine, Toulouse, France d Geriatric Research, Education and Clinical Center, Saint Louis VA, Medical Center and Division of Geriatrics, Saint Louis University, Saint Louis, MO, USA Received 28 July 2006 ; received in revised form 9 October 2006; accepted 10 October 2006
KEYWORDS Physical performance; Physical function
Summary Context: Disability in the obese may be a consequence of low muscle strength and inactivity. Objective: We compared isometric knee extensor strength (KES) between obese (body mass index, BMI >29 kg/m2 ), normal (BMI [24—29]) and lean (BMI < 24) elderly and its association with disability. Then, we investigated the risk of disability in obese, normal, and lean participants according to their physical activity. Methods: 215 obese (80.0 ± 3.5 y, BMI 31.9 ± 2.6), 630 normal (80.2 ± 3.7 y, BMI 26.3 ± 1.4) and 598 lean (80.7 ± 4.1 y, BMI 21.6 ± 1.8) women with good functional ability were studied. A cross-sectional design was used. Anthropometric measures, KES (statometers), health status, self-reported difficulties for physical function, disability (Instrumental and Basic Activity of Daily Living), and recreational physical activities (RPA; walking, gymnastics, cycling, swimming, and gardening) were obtained. Results: KES was negatively and significantly associated with disability and functional difficulties. When KES was adjusted for age, RPA, pain, depression, visual impairment, steroid treatment, comorbidity, osteoporosis and, weight, an interaction effect between the BMI groups and RPA (p = 0.01) was found. KES
∗ Corresponding author at: Service de M´ edecine Interne et de G´ erontologie Clinique, CHU La Grave-Casselardit, 170 avenue de Casselardit, 31300 Toulouse, France. Tel.: +33 561810543; fax: +33 561497109. E-mail address: [email protected] (Y. Rolland).
1871-403X/$ — see front matter © 2006 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.orcp.2006.10.001
40
Y. Rolland et al. significantly decreased in the sedentary women with increasing BMI but was not significantly different in active (≥1 h/week in ≥1 RPA for ≥1 month) women. Association between KES and self-reported difficulties for physical function was significantly lower in the active compared to the sedentary women and was not significantly higher in the active obese women. Conclusions: Low KES is associated with disability and difficulties for physical function in elderly women. The higher level of KES in participants engaged in RPA may prevent disability related to obesity. © 2006 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Introduction
Methods
Obesity is consistently associated with higher levels of disability [1,2] and especially in activities involving the lower body extremities [3]. Weight loss programs in obese have positive short-term effects on disability and functional limitations [4]. However, long-term maintenance of weight loss achieved during dieting is modest [5] and risk of death may increase for elders who lose weight even when they are obese [6]. Increasing strength may be an alternative option to reverse the long-term effects of obesity on disability. Strength predicts functional limitations and disabilities [7] and impaired strength may play an important role in functional disabilities in the obese [8—10]. Moreover, physical activity can increase muscle strength in older subjects [11—13] and may reduce mobility disability, even in obese [14,15]. The mechanisms by which obesity affects disability in the elderly are poorly understood. Usually, the obese have more muscle mass and, therefore, more muscle strength [8,16,17]. However, muscle strength adjusted for weight (functional strength) may be lower in the obese than the non-obese. In the elderly obese, a lower adjusted strength in the lower extremities may be a determinant factor of disability. Moreover, we do not know whether the obese elderly can increase their strength and so avoid the effects of obesity on disability if they are engaged in recreational physical activities (RPA). The aims of this study were:
Data for this study were collected in the EPIDOS study (EPIDemiologie de l’OSteoporose), a prospective epidemiological study, carried out in five French cities (Amiens, Lyon, Montpellier, Paris, Toulouse) to assess the risk factors of hip fracture in the healthy elderly. The sampling and data collection procedures have been previously described in detail [17—19].
- First, to compare lower extremity functional muscle strength in obese, normal, and lean elderly women and investigate the association between lower extremity strength and difficulties in physical functions. - Second, to compare the association with difficulties in physical function (i) between obese and non obese elderly women and (ii) between sedentary and active elderly women.
Population and protocol In brief, from 1992 to 1994, 1454 women aged 75 years and over took part in Toulouse (France) in the EPIDOS study. Participants were sampled from electoral lists. All women aged 75 years or older were invited by mail to participate in the EPIDOS study. To be included, women had to live in the community, to have no previous history of hip fracture or hip replacement, to be able to walk independently, and to be able to understand and answer the questionnaire. We analyzed the data collected during the inclusion visit. All participants gave written informed consent. The program was approved by the Toulouse’s hospital ethical committee.
Demographic and health assessment Baseline examination was performed in a clinical research center by a trained geriatric nurse. A physical examination and a health status questionnaire were used to record comorbid diseases (hypertension, diabetes, dyslipidemia, coronary heart disease, peripheral vascular disease, cancer, stroke, Parkinson’s disease, depression) and pain (pain of the back, hip, knee, ankle, or feet). Cognitive impairment was assessed with the Pfeiffer test [20]. Women were asked to bring all their regular medications to the clinical center. Women were especially asked whether they had osteoporosis, and whether they had taken hormone replacement therapy or steroids during the last 3 months. Vision was assessed by a visual acuity test (Snellen let-
Strength and disability in obese elderly ter test chart). Smoking (previous or current) and alcohol intake were noted. The highest level of education (illiterate, elementary, high school, postgraduate degree) was noted.
Anthropometry Anthropometric measurements were performed by a trained technician using standardized techniques [21]. The reference values of body mass index (BMI = weight/height2 , in units of kg/m2 ) and obesity as a mortality factor in elderly persons are still under discussion [22]. A review of the literature suggests that the optimal BMI range of BMI for elderly people is 24—29 kg/m2 [23]. In accordance with these proposed values for the elderly, obese women were defined in this study as having a BMI greater than 29 kg/m2 and lean women as having a BMI less than 24 kg/m2 .
Evaluation of the knee extensor strength (KES) To measure maximum isometric knee extension, participants were seated in an adjustable straightback chair with the pelvis fixed by a strap and a strength gauge attached by a strap just above the ankle (ADCRO [Association pour le D´ eveloppement de la Chirurgie R´ eparatrice et Orthop´ edique] electronic statometers, Valenton, France) [24]. For analysis, we used the mean of the highest score of three attempts of each leg, recorded in Newtons. Each time, verbal encouragement was given to obtain the maximal score. Knee extensor strength adjusted for weight defined functional knee extensor strength.
Recreational physical activity Participants self-reported in a structured questionnaire whether they regularly practiced recreational physical activities such as walking, gymnastics, cycling, swimming or gardening. Type, frequency, and duration of each recreational physical activity were recorded. Women were considered physically active if they practiced at least one recreational physical activity at least one hour a week for the past month or more.
Disability and physical function assessment Subjects answered a questionnaire about their ability to perform without assistance basic activities and instrumental activities of daily living using the Katz ADL scale (Activity of Daily Living) [25] and Lawton IADL scale (Instrumental Activity of Daily
41 Living) [26]. The IADL scale was composed of 8 items: food preparation, housekeeping, shopping for groceries, doing laundry, handling money, using the telephone, taking medications, using public transport. Participants were asked if they had difficulties (no/some/serious difficulty) in carrying out various physical movements, such as walking, climbing stairs, rising from a chair or bed, picking an object from the floor, lifting heavy objects or reaching an object. For each variable, we grouped together women with some or serious difficulties. We also grouped together women with three or more selfreported difficulties for physical function and called this group, the ‘‘moving difficulties’’ group.
Statistical methods Quantitative variables were expressed as means ± standard deviations (S.D.) and qualitative variables as percentages. Analysis was stratified by BMI groups (BMI 29 kg/m2 ). Variance analysis and Bonferroni multiple comparison tests were used to compare groups for quantitative variables. The chi2 test was used to compare groups for qualitative variables (disability, difficulties in physical function and recreational physical activity). Analysis of the relation between the disability or the difficulties in physical function and functional knee extensor strength in each BMI group (lean, normal, obese) was performed using variance analysis or Kruskall—Wallis test according to the normality of the distribution. A significant interaction effect between the BMI groups and participation in a recreational physical activity for functional knee extensor strength and a strong association between functional knee extensor strength and disability was found. Then, we initially conducted a multiple linear regression analysis to take into account possible confounders that could explain this interaction. Height was included as a potentially confounding factor as it may influence strength independently of weight. Among all potentially confounding factors, age, weight, height, Parkinson’s disease, depression, Pfeiffer score, pain, visual impairment, steroid treatment, and recreational physical activity were associated with muscle strength to a threshold of 0.20 in bivariate analysis. These variables were taken into account for adjustment in the initial model. Stepwise decreasing regression was done to obtain the best reduced model. Weight, age, height, pain, depression and recreational physical activity remained in the final model. We then esti-
42 Table 1 Descriptive anthropometric measures, disability, difficulty for physical function, recreational physical activity, and knee extensor results in lean, normal, and obese elderly women N
Lean BMI* 29 215
p Lean/normal
p† Obese/normal
Age (mean, S.D.) (y) Pfeiffer (mean, S.D.)
80.7 (4.1) 8.7 (1.3)
80.2 (3.7) 8.8 (1.2)
80.0 (3.5) 8.7 (1.4)
0.03 1.0
1.0 1.0
Level of education (%) Illiterate Elementary High school Post-graduate degree
14.7 40.2 31.3 13.7
22.2 38.6 29.5 9.7
23.3 49.8 21.4 5.6
0.010
Osteoporosis Parkinson’s disease Depression Pain Hormone replacement therapy Steroids in the last 3 months Visual acuity (pb de vue) Smoking Alcohol intake
25.6 4.4 11.7 29.1 18.7 1.0 29.3 4.5 51.8
10.0 2.9 13.4 35.2 18.6 1.3 27.0 3.0 46.9
4.2 2.8 14.4 47.4 13.3 0.9 23.4 2.8 44.6
Anthropometric measures Weight (mean, S.D.) (kg) Height (mean, S.D.) (cm) BMI (mean, S.D.) (kg/m2 ) Waist circumference (mean, S.D.) (cm) Calf circumference (mean, S.D.) (cm) Hip circumference (mean, S.D.) (cm)
Difficulties for physical function Moving difficulties§ (%) Rising from a chair (%) Lifting heavy objects (%)
(5.6) (5.7) (1.8) (6.3) (2.4) (4.7)
61.1 152.4 26.3 87.9 35.5 101.6
(5.8) (6.1) (1.4) (6.1) (2.3) (4.9)
73.4 151.5 31.9 99.6 38.7 113.0
25.1 25.1
34.3 34.5
52.6 52.6
4.0
3.3
5.1
25.4 16.7 47.0
35.9 22.9 45.6
51.6 32.6 54.2
(7.7) (5.9) (2.6) (7.7) (2.8) (6.9)
p for trend
0.06 1.0
0.004 0.67
0.024
ORIGINAL ARTICLES
Disability in obese elderly women: Lower limb strength and recreational physical activity Yves Rolland a,b,d,∗, Val´ erie Lauwers-Cances b,c, Christelle Cristini c, H´ el` ene Grandjean b, William A. Banks d, John E. Morley d, Bruno Vellas a,b a
Department of Internal Medicine and Geriatrics, CHU La-Grave-Casselardit, Toulouse, 170 Casselardit Avenue, 31300 Toulouse, France b Inserm 558, IFR 126, Faculty of Medicine, Toulouse, France c Laboratory of Epidemiology and Community Health, Faculty of Medicine, Toulouse, France d Geriatric Research, Education and Clinical Center, Saint Louis VA, Medical Center and Division of Geriatrics, Saint Louis University, Saint Louis, MO, USA Received 28 July 2006 ; received in revised form 9 October 2006; accepted 10 October 2006
KEYWORDS Physical performance; Physical function
Summary Context: Disability in the obese may be a consequence of low muscle strength and inactivity. Objective: We compared isometric knee extensor strength (KES) between obese (body mass index, BMI >29 kg/m2 ), normal (BMI [24—29]) and lean (BMI < 24) elderly and its association with disability. Then, we investigated the risk of disability in obese, normal, and lean participants according to their physical activity. Methods: 215 obese (80.0 ± 3.5 y, BMI 31.9 ± 2.6), 630 normal (80.2 ± 3.7 y, BMI 26.3 ± 1.4) and 598 lean (80.7 ± 4.1 y, BMI 21.6 ± 1.8) women with good functional ability were studied. A cross-sectional design was used. Anthropometric measures, KES (statometers), health status, self-reported difficulties for physical function, disability (Instrumental and Basic Activity of Daily Living), and recreational physical activities (RPA; walking, gymnastics, cycling, swimming, and gardening) were obtained. Results: KES was negatively and significantly associated with disability and functional difficulties. When KES was adjusted for age, RPA, pain, depression, visual impairment, steroid treatment, comorbidity, osteoporosis and, weight, an interaction effect between the BMI groups and RPA (p = 0.01) was found. KES
∗ Corresponding author at: Service de M´ edecine Interne et de G´ erontologie Clinique, CHU La Grave-Casselardit, 170 avenue de Casselardit, 31300 Toulouse, France. Tel.: +33 561810543; fax: +33 561497109. E-mail address: [email protected] (Y. Rolland).
1871-403X/$ — see front matter © 2006 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.orcp.2006.10.001
40
Y. Rolland et al. significantly decreased in the sedentary women with increasing BMI but was not significantly different in active (≥1 h/week in ≥1 RPA for ≥1 month) women. Association between KES and self-reported difficulties for physical function was significantly lower in the active compared to the sedentary women and was not significantly higher in the active obese women. Conclusions: Low KES is associated with disability and difficulties for physical function in elderly women. The higher level of KES in participants engaged in RPA may prevent disability related to obesity. © 2006 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.
Introduction
Methods
Obesity is consistently associated with higher levels of disability [1,2] and especially in activities involving the lower body extremities [3]. Weight loss programs in obese have positive short-term effects on disability and functional limitations [4]. However, long-term maintenance of weight loss achieved during dieting is modest [5] and risk of death may increase for elders who lose weight even when they are obese [6]. Increasing strength may be an alternative option to reverse the long-term effects of obesity on disability. Strength predicts functional limitations and disabilities [7] and impaired strength may play an important role in functional disabilities in the obese [8—10]. Moreover, physical activity can increase muscle strength in older subjects [11—13] and may reduce mobility disability, even in obese [14,15]. The mechanisms by which obesity affects disability in the elderly are poorly understood. Usually, the obese have more muscle mass and, therefore, more muscle strength [8,16,17]. However, muscle strength adjusted for weight (functional strength) may be lower in the obese than the non-obese. In the elderly obese, a lower adjusted strength in the lower extremities may be a determinant factor of disability. Moreover, we do not know whether the obese elderly can increase their strength and so avoid the effects of obesity on disability if they are engaged in recreational physical activities (RPA). The aims of this study were:
Data for this study were collected in the EPIDOS study (EPIDemiologie de l’OSteoporose), a prospective epidemiological study, carried out in five French cities (Amiens, Lyon, Montpellier, Paris, Toulouse) to assess the risk factors of hip fracture in the healthy elderly. The sampling and data collection procedures have been previously described in detail [17—19].
- First, to compare lower extremity functional muscle strength in obese, normal, and lean elderly women and investigate the association between lower extremity strength and difficulties in physical functions. - Second, to compare the association with difficulties in physical function (i) between obese and non obese elderly women and (ii) between sedentary and active elderly women.
Population and protocol In brief, from 1992 to 1994, 1454 women aged 75 years and over took part in Toulouse (France) in the EPIDOS study. Participants were sampled from electoral lists. All women aged 75 years or older were invited by mail to participate in the EPIDOS study. To be included, women had to live in the community, to have no previous history of hip fracture or hip replacement, to be able to walk independently, and to be able to understand and answer the questionnaire. We analyzed the data collected during the inclusion visit. All participants gave written informed consent. The program was approved by the Toulouse’s hospital ethical committee.
Demographic and health assessment Baseline examination was performed in a clinical research center by a trained geriatric nurse. A physical examination and a health status questionnaire were used to record comorbid diseases (hypertension, diabetes, dyslipidemia, coronary heart disease, peripheral vascular disease, cancer, stroke, Parkinson’s disease, depression) and pain (pain of the back, hip, knee, ankle, or feet). Cognitive impairment was assessed with the Pfeiffer test [20]. Women were asked to bring all their regular medications to the clinical center. Women were especially asked whether they had osteoporosis, and whether they had taken hormone replacement therapy or steroids during the last 3 months. Vision was assessed by a visual acuity test (Snellen let-
Strength and disability in obese elderly ter test chart). Smoking (previous or current) and alcohol intake were noted. The highest level of education (illiterate, elementary, high school, postgraduate degree) was noted.
Anthropometry Anthropometric measurements were performed by a trained technician using standardized techniques [21]. The reference values of body mass index (BMI = weight/height2 , in units of kg/m2 ) and obesity as a mortality factor in elderly persons are still under discussion [22]. A review of the literature suggests that the optimal BMI range of BMI for elderly people is 24—29 kg/m2 [23]. In accordance with these proposed values for the elderly, obese women were defined in this study as having a BMI greater than 29 kg/m2 and lean women as having a BMI less than 24 kg/m2 .
Evaluation of the knee extensor strength (KES) To measure maximum isometric knee extension, participants were seated in an adjustable straightback chair with the pelvis fixed by a strap and a strength gauge attached by a strap just above the ankle (ADCRO [Association pour le D´ eveloppement de la Chirurgie R´ eparatrice et Orthop´ edique] electronic statometers, Valenton, France) [24]. For analysis, we used the mean of the highest score of three attempts of each leg, recorded in Newtons. Each time, verbal encouragement was given to obtain the maximal score. Knee extensor strength adjusted for weight defined functional knee extensor strength.
Recreational physical activity Participants self-reported in a structured questionnaire whether they regularly practiced recreational physical activities such as walking, gymnastics, cycling, swimming or gardening. Type, frequency, and duration of each recreational physical activity were recorded. Women were considered physically active if they practiced at least one recreational physical activity at least one hour a week for the past month or more.
Disability and physical function assessment Subjects answered a questionnaire about their ability to perform without assistance basic activities and instrumental activities of daily living using the Katz ADL scale (Activity of Daily Living) [25] and Lawton IADL scale (Instrumental Activity of Daily
41 Living) [26]. The IADL scale was composed of 8 items: food preparation, housekeeping, shopping for groceries, doing laundry, handling money, using the telephone, taking medications, using public transport. Participants were asked if they had difficulties (no/some/serious difficulty) in carrying out various physical movements, such as walking, climbing stairs, rising from a chair or bed, picking an object from the floor, lifting heavy objects or reaching an object. For each variable, we grouped together women with some or serious difficulties. We also grouped together women with three or more selfreported difficulties for physical function and called this group, the ‘‘moving difficulties’’ group.
Statistical methods Quantitative variables were expressed as means ± standard deviations (S.D.) and qualitative variables as percentages. Analysis was stratified by BMI groups (BMI 29 kg/m2 ). Variance analysis and Bonferroni multiple comparison tests were used to compare groups for quantitative variables. The chi2 test was used to compare groups for qualitative variables (disability, difficulties in physical function and recreational physical activity). Analysis of the relation between the disability or the difficulties in physical function and functional knee extensor strength in each BMI group (lean, normal, obese) was performed using variance analysis or Kruskall—Wallis test according to the normality of the distribution. A significant interaction effect between the BMI groups and participation in a recreational physical activity for functional knee extensor strength and a strong association between functional knee extensor strength and disability was found. Then, we initially conducted a multiple linear regression analysis to take into account possible confounders that could explain this interaction. Height was included as a potentially confounding factor as it may influence strength independently of weight. Among all potentially confounding factors, age, weight, height, Parkinson’s disease, depression, Pfeiffer score, pain, visual impairment, steroid treatment, and recreational physical activity were associated with muscle strength to a threshold of 0.20 in bivariate analysis. These variables were taken into account for adjustment in the initial model. Stepwise decreasing regression was done to obtain the best reduced model. Weight, age, height, pain, depression and recreational physical activity remained in the final model. We then esti-
42 Table 1 Descriptive anthropometric measures, disability, difficulty for physical function, recreational physical activity, and knee extensor results in lean, normal, and obese elderly women N
Lean BMI* 29 215
p Lean/normal
p† Obese/normal
Age (mean, S.D.) (y) Pfeiffer (mean, S.D.)
80.7 (4.1) 8.7 (1.3)
80.2 (3.7) 8.8 (1.2)
80.0 (3.5) 8.7 (1.4)
0.03 1.0
1.0 1.0
Level of education (%) Illiterate Elementary High school Post-graduate degree
14.7 40.2 31.3 13.7
22.2 38.6 29.5 9.7
23.3 49.8 21.4 5.6
0.010
Osteoporosis Parkinson’s disease Depression Pain Hormone replacement therapy Steroids in the last 3 months Visual acuity (pb de vue) Smoking Alcohol intake
25.6 4.4 11.7 29.1 18.7 1.0 29.3 4.5 51.8
10.0 2.9 13.4 35.2 18.6 1.3 27.0 3.0 46.9
4.2 2.8 14.4 47.4 13.3 0.9 23.4 2.8 44.6
Anthropometric measures Weight (mean, S.D.) (kg) Height (mean, S.D.) (cm) BMI (mean, S.D.) (kg/m2 ) Waist circumference (mean, S.D.) (cm) Calf circumference (mean, S.D.) (cm) Hip circumference (mean, S.D.) (cm)
Difficulties for physical function Moving difficulties§ (%) Rising from a chair (%) Lifting heavy objects (%)
(5.6) (5.7) (1.8) (6.3) (2.4) (4.7)
61.1 152.4 26.3 87.9 35.5 101.6
(5.8) (6.1) (1.4) (6.1) (2.3) (4.9)
73.4 151.5 31.9 99.6 38.7 113.0
25.1 25.1
34.3 34.5
52.6 52.6
4.0
3.3
5.1
25.4 16.7 47.0
35.9 22.9 45.6
51.6 32.6 54.2
(7.7) (5.9) (2.6) (7.7) (2.8) (6.9)
p for trend
0.06 1.0
0.004 0.67
0.024
