Combined effects of body composition and ageing on joint torque, muscle activation and co-contraction in sedentary women

Abstract

This study aimed to establish the interplay between body mass, adiposity, ageing and determinants of skeletal muscle strength. One hundred and two untrained healthy women categorised by age into young (Y) (mean ± SD, 26.7 ± 9.4 years) vs. old (O) (65.1 ± 7.2 years) were assessed for body fat, lean mass, plantar flexion and dorsiflexion maximum voluntary isometric contraction (MVC) torque, muscle activation capacity and antagonist muscle co-contraction. MVC torque normalised to body mass in the obese group was 35 and 29 % lower (p < 0.05) in Y and 34 and 31 % lower (p < 0.05) in O, compared with underweight and normal weight individuals, respectively. Y with ≥40 % body fat had significantly lower activation than Y with <40 % body fat (88.3 vs. 94.4 %, p < 0.05), but O did not exhibit this effect. Co-contraction was affected by ageing (16.1 % in O vs. 13.8 % in Y, p < 0.05) but not body composition. There were significant associations between markers of body composition, age, strength and activation capacity, with the strongest correlation between muscle strength and total body mass (r2 = 0.508 in Y, p < 0.001, vs. r2 = 0.204 in O, p < 0.01). Furthermore, the age-related loss in plantar flexion (PF) MVC torque was exacerbated in obese compared to underweight, normal weight and overweight individuals (−0.96 vs. −0.54, −0.57 and −0.57 % per year, p < 0.05). The negative impact of adiposity on muscle performance is associated with not only muscular but also neural factors. Overall, the effects of ageing and obesity on this system are somewhat cumulative.

Long-term, but not short-term high-fat diet induces fiber composition changes and impaired contractile force in mouse fast-twitch skeletal muscle

“…Metabolic disorders, such as insulin resistance and type 2 diabetes mellitus, can cause a decrease in muscle strength and loss of muscle mass (Park et al 2006(Park et al , 2009Zhou et al 2007;Lee et al 2011). In addition, previous studies have demonstrated that decreased muscle strength is observed in obese young adults (Maffiuletti et al 2007) and older adults (Zoico et al 2004;Tomlinson et al 2014a). The decreased muscle strength observed in obese subjects may be caused by decreased muscle quantity and/ or quality, which is calculated as muscle strength per unit of muscle mass (Tomlinson et al 2014b).…”

“…; Tomlinson et al. ). The decreased muscle strength observed in obese subjects may be caused by decreased muscle quantity and/or quality, which is calculated as muscle strength per unit of muscle mass (Tomlinson et al.…”

The effects of obesity on skeletal muscle contractile function

“…Obesity can be associated with an increase in the capacity of weight-bearing skeletal muscles to produce absolute force and power for locomotion and postural control (e.g. knee extensor and trunk musculature) (Hulens et al, 2001;Rolland et al, 2004;Lafortuna et al, 2005;Maffiuletti et al, 2007;Abdelmoula et al, 2012;Tomlinson et al, 2014), but it does not affect performance of other skeletal musculature (Hulens et al, 2001;Rolland et al, 2004;Lafortuna et al, 2005). Excess body mass of obese individuals increases the demand placed on the skeletal muscles during standing and locomotion, and this can lead to a beneficial training adaptation in some muscles (Hulens et al, 2001;Lafortuna et al, 2005).…”

Osteosarcopenic Obesity Syndrome: What Is It and How Can It Be Identified and Diagnosed?

“…Fat serves no apparent functional benefit to locomotion other than being an energy storage. It may on the other hand impede [ 18 ] or indirectly inhibit function via adipokine induced low-grade chronic inflammation [ 4 , 5 ].…”