Aging of skeletal muscle: a 12-yr longitudinal study

Abstract

The present study examines age-related changes in skeletal muscle size and function after 12 yr. Twelve healthy sedentary men were studied in 1985-86 (T1) and nine (initial mean age 65.4 +/- 4.2 yr) were reevaluated in 1997-98 (T2). Isokinetic muscle strength of the knee and elbow extensors and flexors showed losses (P < 0.05) ranging from 20 to 30% at slow and fast angular velocities. Computerized tomography (n = 7) showed reductions (P < 0.05) in the cross-sectional area (CSA) of the thigh (12.5%), all thigh muscles (14.7%), quadriceps femoris muscle (16.1%), and flexor muscles (14. 9%). Analysis of covariance showed that strength at T1 and changes in CSA were independent predictors of strength at T2. Muscle biopsies taken from vastus lateralis muscles (n = 6) showed a reduction in percentage of type I fibers (T1 = 60% vs. T2 = 42%) with no change in mean area in either fiber type. The capillary-to-fiber ratio was significantly lower at T2 (1.39 vs. 1. 08; P = 0.043). Our observations suggest that a quantitative loss in muscle CSA is a major contributor to the decrease in muscle strength seen with advancing age and, together with muscle strength at T1, accounts for 90% of the variability in strength at T2.

Proposal for new selection criteria considering pre‐transplant muscularity and visceral adiposity in living donor liver transplantation

“…In addition, a continuous worsening of muscularity and visceral adiposity is generally seen with the ageing process. This change in body compositions has been shown to become pronounced around 50 years old, with faster progression noted after 60 years old 29, 30. In the present study, all body compositions (SMI, IMAC, and VSR) in younger donors (<50 years) were significantly better than those in older donors (≥50 years) in both men ( P  < 0.001 each) and women ( P  < 0.001 each).…”

Sarcopenia and its implications for the elderly

“…Pharmacologic interventions such as growth hormone or testosterone, which increase lean mass (and evidently muscle mass as well) do not alter strength much, while progressive resistance training, which causes large increases in strength, can do so with little evident muscle hypertrophy, at least in the ®rst few months of training. For example, Figure 2 shows the strength and vastus lateralis area (measured by CT scan) lost over a 12 y follow-up period in seven healthy men, and the amount gained during a 12 week period of intensive resistance training (Frontera et al, 2000). It is clear that there is hysteresis in this system: the decline and the regain occur at vastly different rates.…”

Apoptosis and necrosis mediate skeletal muscle fiber loss in age‐induced mitochondrial enzymatic abnormalities

“…In humans, 30% of the muscle mass is lost between 20 and 80 years of age (Frontera et al ., 2000). The muscle mass decline observed in sarcopenia is due to fiber atrophy and loss (Lexell et al ., 1986).…”