An investigation of the association between grip strength and hip and knee joint moments in older adults Dinesh Samuel a, *, Philip Rowe b a Faculty of Health Sciences, University of Southampton, Building 45, Burgess Road, Highfield, Southampton SO17 1BJ, United Kingdom b HealthQWest, Bioengineering Unit, University of Strathclyde, Glasgow G4 0NW, United Kingdom 1. Introduction Age-related loss of muscle strength is associated with increased risk of disability, activity limitation and mortality (Rantanen et al., 1994; Aihie Sayer et al., 2008). Epidemiological studies have highlighted that handgrip strength is a more useful marker of frailty compared to chronological age (Guralnik et al., 1995; Rantanen et al., 1999; Syddall et al., 2003). Grip strength is a good indicator of upper limb performance (Desrosiers et al., 1995) and is often used to characterize the overall muscle strength (Visser et al., 2000; Abbatecola et al., 2005). However lower extremity muscle strength is an important determinant of mobility-based functional activities in older adults (Hortoba ´ gyi et al., 2003; Macaluso and De Vito, 2004). Hence assessment of muscle function in older people is critical for identifying those at risk of disability due to musculoskeletal deficits and initiate interventions for sarcopenia targeted to specific muscle groups (Lynch et al., 1999). Previous investigations involving more than one muscle group have reported that muscle mass and strength of lower extremities is affected to a greater extent with aging compared to the upper limb (Hunter et al., 1998; Lynch et al., 1999; Frontera et al., 2000; Janssen et al., 2000). However comparisons between upper and lower extremity muscle groups were limited to knee and elbow joints and in some cases also included grip strength (Viitasalo et al., 1985; Bemben et al., 1991; Lynch et al., 1999; Frontera et al., 2000; Hunter et al., 2000; Samson et al., 2000; Lauretani et al., 2003; Bazzucchi et al., 2004; Candow and Chilibeck, 2005; Bohannon, 2009). No previous studies were found that examined grip strength measured in conjunction with muscle moments obtained from the major muscle groups of both knee and hip joints. We have attempted to characterize the muscle moments of different muscle groups across two major joints of the lower extremity in a previous publication (Samuel and Rowe, 2009). We observed that the age- related loss of muscle strength was specific to each joint and hence, it is important to compare the moments produced by lower limb muscles to the commonly utilized grip strength measure. The purpose of the present study was (a) to assess the association between grip strength and lower extremity moments in older adults and (b) to compare the profiles of loss of hand grip strength and hip and knee moments with increasing age. 2. Subjects and methods Ethical approval was obtained from the Ethics Committee at the Bioengineering Unit, University of Strathclyde in Glasgow. All participants provided written informed consent prior to partici- pation in the study. Archives of Gerontology and Geriatrics 54 (2012) 357–360 ARTICLE INFO Article history: Received 24 September 2010 Received in revised form 24 February 2011 Accepted 6 March 2011 Available online 9 April 2011 Keywords: Grip strength Knee moment Hip moment Muscle strength Sarcopenia in aging ABSTRACT Grip strength is a predictor of health outcomes but with differing rates of age-related decline in muscle strength, it is unclear whether handgrip is a reliable indicator of lower limb moments. This study investigated the relationship between grip strength and lower extremity moments in community- dwelling older adults. Eighty-two healthy volunteers aged 60–82 years (mean age 73.2 years) performed maximal voluntary contractions of knee and hip extensors and flexors at three positions and at neutral position for hip abductors and adductors using a custom-built dynamometer. Grip strength was measured using an electronic Jamar dynamometer. The relative reduction in muscle strength of 80s age category compared to 60-year-olds ranged from 14% for grip strength to 27% for hip abductors. Peak torque of flexors and extensors of the knee and hip joints were significantly correlated with grip strength and Pearson’s correlation coefficients ranged from 0.56 to 0.78 with the highest correlations observed between knee moments and grip strength. ‘‘Good’’ correlation was found but only 31–60% of the variation in grip strength could be related to changes in joint torques. Hence the assumption that grip strength is an indicator of strength in the lower limb would seem unjustified in the healthy older adult. ß 2011 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. Tel.: +44 02380 598 925; fax: +44 02380 595 301. E-mail address: D.Samuel@soton.ac.uk (D. Samuel). Contents lists available at ScienceDirect Archives of Gerontology and Geriatrics journal homepage: www.elsevier.com/locate/archger 0167-4943/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.archger.2011.03.009