Muscle Quality and Age: Cross-Sectional and Longitudinal Comparisons

Abstract

We addressed whether muscle quality (force per unit muscle mass) changes with age in cross-sectional and longitudinal analyses from three groups from the Baltimore Longitudinal Study of Aging: (1) Isometric arm strength studied cross-sectionally in 617 subjects with muscle mass estimated by cross-sectional area (CSA) from arm circumference and by 24-hour urinary creatinine excretion (CREAT); (2) longitudinal study for 10 to 25 years in 412 men using the same measures as the first group; and (3) isometric knee extensor strength studied cross-sectionally in 675 subjects; muscle mass estimated by CREAT, CSA from thigh circumference, and leg nonosseous fat free mass (FFM) from dual energy x-ray absorptiometry. Muscle quality declined in both arm and leg with age in cross-sectional analyses using CSA and FFM, but not CREAT. No age-associated arm muscle quality declines were observed longitudinally using CREAT or CSA. The relationship between muscle quality and age is dependent on how muscle mass is estimated and on whether subjects are studied cross-sectionally or longitudinally. In addition, CREAT may measure a muscle property not accounted for by CSA or FFM.

Accelerated Loss of Skeletal Muscle Strength in Older Adults With Type 2 Diabetes

“…Sarcopenia, a status of decreased skeletal muscle mass, is commonly observed in older adults as a result of age-related loss of muscle mass (17)(18)(19)(20)(21). In general, it is frequently accompanied by lower skeletal muscle strength.…”

Association of Muscle Endurance, Fatigability, and Strength With Functional Limitation and Mortality in the Health Aging and Body Composition Study

“…Most human studies of skeletal muscle function have focused on isometric measurements of muscle strength and imaging assessments of muscle size and composition (7)(8)(9)(10). However, isometric tests are limited by static assessment of muscle strength at maximal contraction.…”

May the Power Be With Us

“…The age-related decline of neuromuscular functioning is related mainly to muscle loss (sarcopenia), changes in muscle quality and neuromuscular control. The relative contribution of the progressive reduction of muscle mass (sarcopenia) and decreasing muscle quality to this age-related decline in muscle performance remains uncertain [8]. As muscular strength is mainly dependent on the cross-sectional area of the muscle [9], the decrease occurring in muscle mass with age results in the decline of their strength, although quantitative changes of muscles with age do not fully explain this decline in muscle strength [8].…”

“…The relative contribution of the progressive reduction of muscle mass (sarcopenia) and decreasing muscle quality to this age-related decline in muscle performance remains uncertain [8]. As muscular strength is mainly dependent on the cross-sectional area of the muscle [9], the decrease occurring in muscle mass with age results in the decline of their strength, although quantitative changes of muscles with age do not fully explain this decline in muscle strength [8]. Infiltration of muscle by fat tissue in well functioning older persons is associated with poorer muscle function than could not be expected only from the volume of muscle [10].…”