Muscle quality. I. Age-associated differences between arm and leg muscle groups

Abstract

To determine the differences between arm and leg muscle quality (MQ) across the adult life span in men and women, concentric (Con) and eccentric (Ecc) peak torque (PT) were measured in 703 subjects (364 men and 339 women, age range 19-93 yr) and appendicular skeletal muscle mass (MM) was determined in the arm and leg in a subgroup of 502 of these subjects (224 men and 278 women). Regression analysis showed that MQ, defined as PT per unit of MM, was significantly higher in the arm ( approximately 30%) than in the leg across age in both genders (P < 0.01). Arm and leg MQ declined at a similar rate with age in men, whereas leg MQ declined approximately 20% more than arm MQ with increasing age in women (P </= 0.01 and P < 0.05 for Con and Ecc PT, respectively). Moreover, the age-associated decrease in arm MQ was steeper in men than in women whether Con or Ecc PT was used (both P < 0.05). Arm MQ as determined by Con PT showed a linear age-related decline in men and women (28 and 20%, respectively, P < 0.001), whereas arm MQ as determined by Ecc PT showed a linear age-related decline in men (25%, P < 0.001) but not in women (not significant). In contrast, both genders exhibited an age-related quadratic decline in leg MQ as determined by Con PT ( approximately 40%) and Ecc PT ( approximately 25%; both P < 0.001), and the rate of decline was similar for men and women. Thus MQ is affected by age and gender, but the magnitude of this effect depends on the muscle group studied and the type of muscle action (Con vs. Ecc) used to assess strength.

Age-related decline in muscle mass and muscle function in Flemish Caucasians: a 10-year follow-up

“…Aging-related declines were greater in the oldest age category compared to the younger age categories. Also, the finding of an aging-related decrease in strength performance, but not in handgrip strength, is consistent with the findings of a differential aging of upper and lower extremities as noted by Lynch et al (1999) and Newman et al (2003).…”

Grip strength and healthy aging

“…A shift in criteria may be associated with age-related changes in muscle quality 28) . Muscle quality decreases in accordance with motor unit loss 29) and fat infiltration into the muscle 30) with aging; therefore, muscle mass may not sufficiently correlate with muscle function in later life.…”

Optimal health and function among the elderly: lessening severity of ADL disability

“…This loss of strength with age is due to many factors, but is primarily attributed to a loss of muscle mass leading to sarcopenia [22]. Because sarcopenia is related to a loss of functional abilities [58], dependency [58], increased risk of falls, fractures [2,40], and decreased bone mineral density [64], it has negative consequences for the health status and functional abilities of older adults. With advancing age, a further decrease in lean body mass may occur, together with the increase in adipose tissue mass typical with aging [13,28,69].…”