Decrements of mobility and power in recreationally active septuagenarians is related to loss of force, but not slowing of the muscle: a 5-year longitudinal study

Abstract

A lesser 6-min walk distance (6MWD) and timed up-and-go (TUG) in old compared with young adults was previously linked to slowing of muscle contractile properties. The purpose of the present study was to determine whether any further reductions in 6MWD and TUG over a 5-year period in septuagenarians are associated with further slowing of muscle contractile properties. We measured muscle function by a countermovement jump, isometric maximal knee extensor strength (MVC) on a dynamometer and quadriceps muscle size by magnetic resonance imaging (MRI) in 17 older women (71.1 ± 2.8 y) and 17 older men (71.3 ± 4.1y). Performance in TUG and 6MWD were reduced over the 5-year period, irrespective of sex (P < 0.001), and both were correlated with power at both baseline and follow-up (R ≥ 0.53; P ≤ 0.001). Jump take-off velocity (VCMJ) was slower at follow-up (P < 0.01) and correlated with 6MWD and TUG at both baseline and follow-up in both sexes (R ≥ 0.54; P ≤ 0.001). However, the relationship between ‘body mass: maximal muscle force ratio’ with VCMJ was not significantly changed, indicating that the lower VCMJ was attributable to muscles working at a higher relative load, hence a lower part of the force–velocity relationship, due to a reduction in MVC (body mass had not changed significantly), rather than slowing of the muscle. The lower VCMJ in women than men (P < 0.001) was likewise attributable to a lower MVC rather than slower contractile properties in women. In conclusion, the decrement in 6MWD and TUG in septuagenarians is due to a loss of muscle mass, rather than further loss of muscle quality.

Age-related and cancer-related sarcopenia: is there a difference?

“…Indeed, after the age of 70, the muscle mass declines by 0.5-1.0% per year, the decline being different by sex, close to 1% per year in men and 0.7% per year in women after 75 years, with an even steeper decline in muscle strength of 3-4% in men and 2.5-3% women. Recently, Cameron et al [10] showed that over 5year period healthy septuagenarians lost about 4.5-5% of their appendicular lean muscle mass and Teraz et al [11] reported a 4.5% decrease of skeletal muscle index over an 8 period of follow up of 69 healthy and active older adults (mean baseline age 68.3 years). It is worthy of note that, however, the age-related changes are not uniform across all muscles and the extent of sarcopenia varies between muscles in different locations with different functions.…”