Study of differences in peripheral muscle strength of lean versus obese women: an allometric approach

Abstract

OBJECTIVE: To investigate whether peripheral muscle strength is signi®cantly different between lean and obese women controlled for age and physical activity, using an allometric approach. DESIGN: Cross-sectional study of isometric handgrip and isokinetic leg and trunk muscle strength. SUBJECTS: 173 obese (age 39.9 AE 11.4 y, body mass index (BMI) 37.8 AE 5.3 kgam 2 ) and 80 lean (age 39.7 AE 12.2 y, BMI 22.0 AE 2.2 kgam 2 ) women. MEASUREMENTS: Anthropometric measures (weight, height) and body composition (bioelectrical impedance method), isometric handgrip (maximal voluntary contraction on the Jamar dynamometer), isokinetic trunk¯exion ± extension, trunk rotation, and knee¯exion ± extension (Cybex dynamometers). RESULTS: Absolute isokinetic strength output (that is, strength uncorrected for fat-free mass) was larger in obese compared to lean women, except for knee¯exion and isometric handgrip, which were not signi®cantly different (P b 0.05). Pearson correlation coef®cients between strength measures and fat-free mass (kg) were low to moderate both in lean (r 0.28 ± 0.53, P`0.05) and in obese (r 0.29 ± 0.49, P`0.001) women. There was no correlation with fat mass (kg) in the lean, whereas in the obese women a weak positive relation could be observed for most isokinetic data (r 0.21 ± 0.39, P`0.01). When correcting for fat-free mass (raised to the optimal exponent determined by allometric scaling), all strength measurements were at least 6% lower in obese when compared to the lean women, except for trunk¯exion, which was at least 8% stronger in obese women. DISCUSSION: The higher absolute knee extension strength measures of leg and the similar extension strength of the trunk in the obese sample compared to the lean might be explained by the training effect of weight bearing and support of a larger body mass. However when the independent effect of fat-free mass is removed, these strength measures, as well as oblique abdominal muscle and handgrip strength, turned out to be lower in obese women. These observations could be the re¯ection of the overall impairment of physical ®tness as a consequence of obesity and its metabolic complications.

Obesity and related consequences to ageing

“…Forbes et al (1983) reported that most obese individuals, children as well as adults, have increased lean weight and that DIO results in both fat mass and lean mass augmentation (Forbes and Welle 1983). This and other results showing stable lean mass during the development of obesity (Hulens et al 2001) suggest that carrying greater weight may have physical traininglike effects (Hulens et al 2001). There is confusion on how to interpret changes in lean mass associated with muscle separately from non-muscle fat-free mass, that is, liver, intestine, kidney, and heart, which indeed might be enlarged with the development of obesity (Masgrau et al 2012).…”

The Chitranjan Ranawat Award: The Nonoperated Knee Predicts Function 3 Years after Unilateral Total Knee Arthroplasty

“…As stated, aging affects strength of the knee extensors [6,10]. We believe the slower stair climbing score is a result of declining strength: stair ascent requires concentric muscle action against gravity repeatedly, while the descent requires eccentric control of the quadriceps.…”

“…Patients with TKA were stable on tests of functional performance and self-report outcome measures during this investigation; however, lower scores on functional tests compared to controls indicate their level of function was not as good as individuals without osteoarthrosis. Aging affects strength of the knee extensors [6,10] and played a role in declining strength [9] in these individuals who were tested over the course of several years. The decline in strength in the nonoperated limb was clearly steeper than that of the control subjects suggesting more than aging was at play.…”

Waist circumference and BMI are independently associated with the variation of cardio-respiratory and neuromuscular fitness in young adult men

“…The results are inconsistent, but many studies suggest that obese individuals have increased absolute muscle strength, at least in some of the measured muscles. 20,21 Adjustment to muscle mass may change the association between obesity and muscle strength to neutral 21 or negative. 20 The results are also dependent on the studied muscle groups and their actions, for example, leg vs arm, dynamic vs isometric, etc.…”

“…20,21 Adjustment to muscle mass may change the association between obesity and muscle strength to neutral 21 or negative. 20 The results are also dependent on the studied muscle groups and their actions, for example, leg vs arm, dynamic vs isometric, etc. 21 A paucity of information exists regarding the effects of strength training on abdominal obesity.…”