Relationships between physical activity and muscular strength among healthy adults across the lifespan

Leblanc et al. SpringerPlus (2015) 4:557 DOI 10.1186/s40064-015-1357-0 Open Access RESEARCH Relationships between physical activity and muscular strength among healthy adults across the lifespan Allie Leblanc1,4*, Beth A. Taylor3, Paul D. Thompson3, Jeffrey A. Capizzi3, Priscilla M. Clarkson2, C. Michael White1 and Linda S. Pescatello1 Abstract The purpose of this study was to examine relationships between objective and self-report measures of physical activity and muscle strength among healthy adults ranging in age from 20 to 91 years. Participants (n = 412) were mostly Caucasian men (48 %) and women (52 %) 43.9 ± 16.1 year of age with a body mass index (BMI) of 26.4 ± 4.8 kg/m2. Physical activity was measured objectively with an accelerometer and by self-report with the Paffenbarger Physical Activity Questionnaire. Upper and lower body muscle strength were measured with an isokinetic dynamometer and handgrip strength with a static dynamometer. Multivariate regression assessed relationships between physical activity and muscle strength. The strongest correlates of upper body strength including handgrip strength were gender (r = −0.861 to −0.716), age (r = −0.445 to −0.241), BMI (r = 0.134–0.397), and physical activity (r = 0.093–0.186). The strongest correlates of lower body strength were gender (r = −0.772 to −0.634), age (r = −0.663 to −0.445), BMI (r = 0.160–0.266), and physical activity (r = −0.139 to 0.151). The strongest correlates of muscle strength were gender (explaining 40–74 % of the variance), age (6–44 %), and BMI (2–16 %), while physical activity correlations were weaker (1–3 %). Conflict surrounding the influence of a physically active lifestyle on muscle strength with age may be due to the stronger influences of other factors that supersede those of physical activity whether measured objectively or by self-report methods. Keywords: Accelerometer, Isokinetic dynamometer, Physical activity, Muscle strength, Classification, Methods, Aging Background Regular participation in physical activity promotes healthy weight, bone mass, and muscle function as well as prevents falls and fractures in older adults. These and other numerous health benefits ultimately extend active life expectancy (USA Department of Health and Human Services 2008). Physical inactivity is a major determinant of the loss of muscle strength as is gender, aging, and body mass index (BMI) (Hollmann, Struder, Tagarakis, and King 2007; Hortobagyi, Katch, Katch, LaChance, and Behnke 1990; Musselman and Brouwer 2005). Maximum muscle strength is typically achieved between 20 and 30 year (Bosco and Komi 1980) and begins to decline *Correspondence: 4 31 Silversmith Rd, Unionville, CT 06085, USA Full list of author information is available at the end of the article around an age of 40 year (Kallman, Plato, and Tobin 1990). After 70 year, overall muscle strength declines 3.6 % annually for men and 2.8 % for women (Goodpaster et al. 2006). Nonetheless, the literature on relationship between physical activity and muscle strength as modulated by age is mixed. Utilizing a self-report physical activity questionnaire, (Paalanne et al. 2009) found greater maximal isometric trunk muscle strength measured by a computerized dynamometer among 874 healthy, young men and women with high levels of moderate to vigorous intensity physical activity compared to those with lower levels of physical exertion. Rantanen et al. (1997) found physical activity assessed by questionnaire positively associated with maximal isometric strength of several muscle groups evaluated by an dynamometer among 287 older adults. © 2015 Leblanc et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Leblanc et al. SpringerPlus (2015) 4:557 Sandler et al. (1991) found physical activity as assessed by the Paffenbarger physical activity questionnaire (Paffenbarger, Wing, and Hyde 1978) positively correlated with muscle strength assessed by a dynamometer among a sample of 620 middle-aged to older women. Furthermore, these investigators found physical activity to be the second largest contributor to the variance in muscle strength (r = 0.54) second to age (r = 0.48) (Sandler et al. 1991). Forrest et al. (2007) also assessed physical activity using the Paffenbarger physical activity questionnaire (Paffenbarger et al. 1978) in a sample of about 20,000 older women and found physical activity positively associated with handgrip strength measured via dynamometry. Jakobsen et al. (Jakobsen, Rask, and Kondrup, 2010) found physical activity assessed with the Baecke questionnaire positively associated with handgrip strength in women, but not men ranging in age from 25 to 65 year. In contrast, other investigators utilizing self-report physical activity questionnaires have found no correlation with physical activity and muscle strength among older populations of men and women (Bryant, Trew, Bruce, and Cheek 2007; Daly et al. 2008). Collectively, in these studies, several investigative employed self-report questionnaires that were validated (Bryant et al. 2007; Forrest et al. 2007; Jakobsen et al. 2010; Rantanen et al. 1997; Sandler et al. 1991), while others did not (Daly et al. 2008; Paalanne et al. 2009), perhaps contributing to the inconsistencies in this literature. Adding to these divergent findings are the two studies assessing physical activity with an accelerometer. Gerdhem et al. (Gerdhem, Dencker, Ringsberg, and Akesson, 2008) found physical activity assessed with an accelerometer did not correlate with knee extension and flexion muscle strength among 57 older women. Similarly, Morie et al. (2010) found no differences in upper body and lower extremity muscle strength between the low and high physical activity groups measured by an accelerometer among 82 older men. Reasons for the discrepancies among studies examining the relationships between physical activity and muscle strength are unclear but could reside in the methods that were used to assess physical activity and muscle strength as well as differences in the characteristics of the population studied. Previous reports (Bryant et al. 2007; Daly et al. 2008; Forrest et al. 2007; Gerdhem et al. 2008; Jakobsen et al. 2010; Morie et al. 2010; Paalanne et al. 2009; Rantanen et al. 1997; Sandler et al. 1991) have examined either self-report or objective measures of habitual physical activity and measures of muscle strength in populations with narrow age ranges and that may have included only one gender. Additionally, examination of other factors that have been documented to influence Page 2 of 10 the relationship between physical activity and muscle (...truncated)