Journal of Strength and Conditioning Research, 2007, 21(4), 1310–1314 䉷 2007 National Strength & Conditioning Association
AGE-RELATED DECLINE IN HANDGRIP STRENGTH DIFFERS ACCORDING TO GENDER LAURO C. VIANNA,1 RICARDO B. OLIVEIRA,1
AND
CLAUDIO GIL S. ARAU´JO1,2
Physical Education Graduate Program, Gama Filho University, Rio de Janeiro, Brazil; 2Exercise Medicine Clinic, CLINIMEX, Rio de Janeiro, Brazil. 1
ABSTRACT. Vianna, L.C., R.B. Oliveira, and C.G.S. Arau´jo. Agerelated decline in handgrip strength differs according to gender. J. Strength Cond. Res. 21(4):1310–1314. 2007.—It is well-established that at old age there is a significant decline in muscle strength. Reference values for muscle strength might be useful for assessment of muscle impairment and of physiological adaptations. However, it is still unclear whether gender affects the rate of decline. Therefore, the aim of this study is to investigate the effect of gender and age on handgrip strength and to establish reference values for this variable. Reviewing medical charts collected from 1994 to 2005, a convenience sample of 2,648 subjects (1,787 men and 861 women), aged between 18 and 90 years, was obtained. Our results show higher handgrip strength for men compared with women (36.8 ⫾ 0.20 vs. 21.0 ⫾ 0.18 kg; p ⬍ 0.001). The regression analysis with a quadratic model shows that aging accounts for 30% of the variance in handgrip strength (r2 ⫽ 0.30; p ⬍ 0.001) in men and 28% (r2 ⫽ 0.28; p ⬍ 0.001) in women. In addition, the bent linear regression with multiple regressors show that a faster decline in handgrip strength occurs at the age of 30 years for men and 50 years for women. We conclude that handgrip strength decline with age differs between genders, making useful the existence of distinct male and female normative age group data. KEY WORDS. handgrip dynamometry, normative data, kinanthropometry
INTRODUCTION uscle strength reduction is one of the most important biological changes that occur with advancing age (4, 30), even though progressive strength training can lead to substantial increases in maximal strength and muscle mass in older women and men (13). Muscle strength presents a curvilinear relationship to age, which results in an initial increment in strength with increasing age, to reach a peak during the third decade of life, and then a decrease with age (4, 12, 30). Although it is well established that at old age there is a significant decline in muscle strength (27), it is still unclear whether gender influences this rate of decline. Some data suggest that muscle strength decline seems to occur at a different age in men compared with women (17, 28). This reduction in muscle strength, due to contractile changes (8), biochemical changes, and disuse, can lead to functional impairment (4, 27, 28), falls (21), and death (11). Reference values for muscle strength might be useful for assessment of muscle impairment, evaluation of interventions, and physiological adaptations (19). In this sense, muscle strength has been measured in healthy and unhealthy subjects and in different age groups (5, 7, 14, 17, 18, 28). Numerous protocols for strength assessment involve a variety of methods or tools. One of the cheapest and most commonly used tests, handgrip strength, has been used in a variety of clinical areas and for multiple purposes, such as part of an overall fitness assessment
M
(14, 23), as well as a simple method for prescribing maximal safe carrying load in patients who have had myocardial infarction (10). In addition, handgrip strength testing is fast, easy to perform, and reliable (29); produces a result that is simple to record; and can predict outcomes (3, 11, 14). Therefore, the main purpose of this cross-sectional study was to determine, on the basis of a large sample size with wide age range, the effect of gender and age on handgrip strength and to establish reference values for this variable in adults of both genders aged between 18 and 90 years.
METHODS Experimental Approach to the Problem
Through a cross-sectional design, this study sought to determine whether the age-related decline in handgrip strength is different between men and women. First, we decided to account for the rate of loss of handgrip strength according to gender. In addition, through a mathematical model, we sought to show whether the acceleration in the decline in handgrip strength occurs at specific boundary ages according gender. Finally, we establish reference values for handgrip strength. Subjects
We retrospectively studied data from 1,787 men (mean age 53 years, range 18–91 years) and 861 women (mean age 52 years, range 18–88 years) who completed a comprehensive medical evaluation between 1994 and 2005 for clinical reasons (preventive check-up, clinical diagnosis, or more often, exercise prescription) in a private exercise medicine clinic, CLINIMEX. Almost all of the subjects were white and belonged to the upper socioeconomic strata. All subjects read and signed the consent form that had been previously approved by the ethics committee and institutional review board. Procedures
All measurements were made in a room free from external distractions in which only the physician or a nurse assistant and the subject were present. Standing height and body weight were determined by standard procedures (22). Handgrip strength (kg) was measured with a specific digital dynamometer (Digital Grip Dynamometer, Takei Kiki, Kogyo, Japan). The size of the grip was adjusted so that the subject felt comfortable. Subjects stood upright and held the dynamometer close to their body with the arm fully extended. The subject maximally squeezed the grip, with 2 attempts in each hand, normally starting on the right side. The best value in the 4 attempts was chosen for further analysis. Although we have not verified and published our reliability data, this is not different
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HANDGRIP STRENGTH TABLE 1.
AND
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Characteristics of the sample.
Height (cm) Weight (kg)
Men (n ⫽ 1,787)
Women (n ⫽ 861)
Mean ⫾ SE
Mean ⫾ SE
95% CI
p
173.1 ⫾ 0.17 82.1 ⫾ 0.38
160.5 ⫾ 0.23 66.7 ⫾ 0.48
12.5–13.6 14.2–16.6
⬍0.001 ⬍0.001
P50, P60, P75, P90, and P95 percentiles. A significance level of 5% and a confidence interval of 95% were used for all statistical testing.
RESULTS Characteristics of the sample according to gender are presented in Table 1. Men were significantly taller and heavier than women. As expected, handgrip strength is greater among men than among women (36.8 ⫾ 0.20 vs. 21.0 ⫾ 0.18 kg; p ⬍ 0.001; Figure 1). This difference persists among all age groups (Tables 2 and 3); thus, it appears to be practical and convenient to split the sample into 2 groups (men and women) to better represent strength and age relationships. Both men and women experience age-related losses in handgrip strength. The regression analysis with a quadratic model shows that age explained losses in handgrip strength, accounting for 30% (r2 ⫽ 0.30; p ⬍ 0.001) of the variance in men and 28% (r2 ⫽ 0.28, p ⬍ 0.001) in women. Table 4 presents the multiple regression analysis for handgrip strength values with the best fit equations. Figures 2 and 3 illustrates that the handgrip strength and age relationship was not linear for both genders. So, the use of bent regression analysis improved the fit of the regression model. Figures 2 and 3 and Tables 2 and 3 show a faster decline in handgrip strength values at the age of 30 years for men and at the age of 50 years for women. By examining percentile tables, some interesting observations can be drawn. The age decline in median value is such that the median score at the oldest age group is only about 60% of that seen in young adults of same gender. In addition, handgrip strength data is quite variable for individuals of the same gender and age, with large interquartile differences ranging, for most age groups, from 5 to 10 kg or about 30% of the median value. Results from the 95th percentile for a given age group are typically equivalent to median scores seen in subjects 30–40 years younger. Men significantly outperform women in all age groups, in that a median score for young women (age 18–25 years) is similar to the fifth percentile for men
FIGURE 1. A box-and-whiskers plot of men (n ⫽ 1,787) and women (n ⫽ 861) for handgrip strength.
from that usually offered (1, 2, 28). In addition, almost all strength measurements (70%) were supervised and obtained by the senior author (C.G.S.A.). Statistical Analyses
All analyses were conducted with the Statistical Package for the Social Sciences, version 13 (SPSS, Inc., Chicago, IL). The unpaired Student’s t-test was used to compare means (handgrip strength, height, and weight) between men and women. Quadratic regression analysis was calculated to determine the variation in handgrip strength with aging. Also, we used the bent linear regression (28) with multiple regressors (e.g., age, weight, height) to determine whether the changes in handgrip strength value might tend to be more rapid at a particular boundary age. On the basis of the loess smoother curve, we tested boundary ages with the use of dummy variables (6). The data are presented stratified by age, stating the maximal handgrip strength value, as well as the P5, P10, P25, P40, TABLE 2.
Handgrip strength reference values for men by percentile (P). Handgrip strength (kg)
Age (y)
n (1,787)
P5
P10
P25
P40
P50
P60
P75
P90
P95
18–25 26–30 31–35 36–40 41–45 46–50 51–55 56–60 61–65 66–70 71–75 76⫹
77 72 122 144 175 189 208 215 180 168 132 105
28.8 27.8 29.6 28.4 28.2 28.1 25.1 25.3 21.5 19.7 19.9 16.3
31.4 31.4 32.1 31.0 31.2 30.3 28.5 27.8 24.5 23.1 21.7 18.3
36.3 38.1 38.6 35.8 36.3 34.3 32.4 31.8 28.8 27.2 24.7 21.7
39.2 40.5 41.4 38.8 39.6 36.9 35.3 34.1 32.2 30.2 28.3 24.1
42.1 43.1 43.1 41.1 40.8 38.3 36.5 35.9 34.1 31.5 30.9 25.8
44.0 44.8 44.2 42.9 43.5 39.6 38.1 37.4 35.7 32.3 31.9 27.7
47.1 47.1 47.6 46.5 46.8 42.9 40.7 40.9 38.5 35.4 34.1 31.5
50.9 52.2 52.0 50.9 49.8 47.5 46.2 46.3 42.1 38.7 38.2 35.4
52.1 55.7 56.1 51.6 53.2 49.6 49.5 50.2 44.5 42.3 40.4 37.1
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VIANNA, OLIVEIRA,
TABLE 3.
AND
ARAU´JO
Handgrip strength reference values for women by percentile (P). Handgrip strength (kg)
Age (y)
n (861)
P5
P10
P25
P40
P50
P60
P75
P90
P95
18–25 26–30 31–35 36–40 41–45 46–50 51–55 56–60 61–65 66–70 71–75 76⫹
49 34 48 80 81 94 114 89 83 71 52 66
14.1 16.1 15.4 14.3 14.9 15.0 12.6 14.4 13.2 8.5 11.1 7.6
15.9 17.1 16.8 16.8 16.6 16.6 14.9 14.9 13.9 13.3 11.5 9.3
20.6 20.4 21.0 20.1 19.4 19.8 18.2 16.7 16.4 15.4 14.1 11.4
24.2 22.1 23.3 22.4 21.2 21.5 20.2 19.5 18.7 16.8 15.4 12.7
25.8 22.6 24.2 23.5 23.2 22.7 21.7 20.2 19.5 17.7 15.8 14.6
27.0 23.9 24.9 24.8 24.4 23.7 22.8 21.7 20.2 18.8 17.1 15.8
30.8 26.6 28.3 26.7 27.1 25.9 24.5 23.3 22.3 20.2 18.8 17.4
33.7 30.6 31.2 28.7 29.1 28.5 28.1 25.0 25.8 23.4 20.4 19.7
34.5 32.4 31.9 30.1 29.4 30.3 30.0 27.6 27.0 23.9 22.2 22.1
of the same age and to the median score for the oldest men (76⫹ years of age).
DISCUSSION In this cross-sectional study, we measured muscle strength with handgrip strength testing over a wide age range and with a large sample size to identify aging and gender profiles. We also propose reference values and determine the influence that gender has on the relationship between strength and age. In fact, the data of this retrospective study show that gender has an influence on handgrip strength, so that, for similar ages, males have higher strength levels than females. Thus, it provides justification for both genders, as has been the case in other studies. The significant variation of the slope for handgrip strength in women and men around the age of 50 and 30 years, respectively, are of interest. Structural and functional modifications occur in skeletal muscle mass during aging (8, 20). These changes lead to impairment in muscle strength, contractile capacity (20), and performance (11, 21, 26). However, age-related muscle strength modification seems to be larger at a specific boundary age (4, 30). In accordance with Samson et al. (28), decline in muscle strength accelerates at about the age of 55 in women, probably because of menopause (25). In this same study, however, they found a linear pattern between handgrip strength and age among men (28). Interestingly, contrary to their results, we found a curvilinear pattern for handgrip strength declines with age in men. In this sense, Kallman et al. (16), from cross-sectional analysis of 847 subjects from 20 to 100 years, reported that handgrip strength peaked in the fourth decade and then declined in a curvilinear fashion thereafter. Moreover, Janssen et al. (15) observed a decline in skeletal muscle mass beginning in the third decade; however, this did not become clinically significant until the fifth decade. Our study findings are consistent and contribute, on the basis of our large sample size and wide age range, that men’s handTABLE 4. Gender Male Female
grip strength reaches a peak at 30 years and then decreases with increasing age. Age-associated loss of muscle mass appears to be inevitable and is likely the most significant contributing factor to the decline in muscle strength. Nonetheless, men exhibited larger age-related decreases in muscle mass compared with women. Using a whole body magnetic resonance imaging to determine skeletal muscle mass, Janssen et al. (15) showed that men had significantly greater skeletal muscle mass than women with greater losses of skeletal muscle mass with aging. Although ␣-motoneuron loss could be largely responsible for age-related loss of muscle mass (9), the mechanisms leading to greater losses of muscle mass with aging in men compared with women are unknown but have been postulated to relate to hormonal factors, including growth hormone, insulin-like growth factor, and testosterone (9, 15, 24). Nevertheless, our study brings to the fore the discussion that the starting point in muscle strength seems to be different according gender. Our study presents some features and limitations that should be noted. We must consider a limitation of the study to be that it presents reference values for the best trial handgrip strength between hands rather than dominant and nondominant hands. However, our presentation and measurement is similar to Samson et al. (28). Another limitation is that handgrip strength percentile values were considered together for all subjects that are at least 76 years old. In this sense, although the analysis for reference values is based on age and gender, it does not account for anthropometric factors (e.g., height). Cross-sectional and longitudinal studies have shown that height is directly correlated to handgrip strength, probably because height is the factor that is more closely related to lean body mass (14, 18, 27). On the other hand, our statistical analysis indicated that the effect of height does not warrant stratification of the handgrip values according to this variable because it would only marginally improve the information already available through strat-
Multiple regression analysis for handgrip strength values. B0
B1
B2
B3
B4
F
p
Multiple R
⫺33.43 0.29 0.37 0.05 ⫺0.57 321.1 0.000 0.65 Y ⫽ B0 ⫹ B1(age) ⫹ B2(height) ⫹ B3(weight) ⫹ B4(age ⫺ 30)D, where D ⫽ 0 if age ⬍30; otherwise, D ⫽ 1. Standard error of the estimate ⫽ 6.5 kg. ⫺16.31 ⫺0.07 0.25 0.03 ⫺0.12 128.06 0.000 0.61 Y ⫽ B0 ⫹ B1(age) ⫹ B2(height) ⫹ B3(weight) ⫹ B4(age ⫺ 50)D, where D ⫽ 0 if age ⬍50; otherwise, D ⫽ 1. Standard error of the estimate ⫽ 4.4 kg.
HANDGRIP STRENGTH
AND
AGING 1313
be useful for a coach’s assessment of muscle impairment, evaluation of interventions, and physiological adaptations. Also, it can be employed in a clinical setting to document whether an individual is impaired relative to subjects of the same gender and age.
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FIGURE 2. Scatter plot for handgrip strength results in men (n ⫽ 1,787). Dashed line identifies the boundary age at which a faster decrease is observed. Continuous line represents the loess smoother curve.
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FIGURE 3. Scatter plot for handgrip strength results in women (n ⫽ 861). Dashed line identifies the boundary age at which a faster decrease is observed. Continuous line represents the loess smoother curve.
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Acknowledgments Lauro C. Vianna was supported by a scholarship from Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´gico (CNPq)— Brazil (142017/2006-0), and Dr. Claudio Gil S. Arau´jo received a grant from CNPq for scientific production.
Address correspondence to Dr. Claudio Gil S. Arau´jo,
[email protected].
