The Copenhagen Sarcopenia Study: lean mass, strength, power, and physical function in a Danish cohort aged 20-93 years

Abstract

Background: Despite no international consensus on the diagnostic criteria for sarcopenia, low lean mass, muscle strength, and physical function are important risk factors for disability, frailty, and mortality in older individuals, as well as in a wide range of patients with muscle loss. Here, we provide a population-based reference material of total and regional lean body mass, muscle strength/power parameters, and physical function in a healthy cohort of Danish men and women across the lifespan.

Methods: Volunteers aged 20-93 years from the Copenhagen City Heart Study were invited to establish a Danish reference material (Copenhagen Sarcopenia Study) on lean mass characteristics [appendicular lean mass (ALM), iDXA, GE Lunar], muscle function [handgrip strength (HGS), Jamar dynamometer and leg extension power (LEP), Nottingham Power Rig], and physical function [30 s sit-to-stand test (STS), 10-m maximal and habitual gait speed (GS)].

Results: A total of 1305 participants [729 women (age: 56.4 ± 18.9 years, height: 1.66 ± 0.01 m, body mass index: 24.6 ± 4.3 kg/m² and 576 men, age: 57.0 ± 17.5 years, height: 1.80 ± 0.07 m, body mass index: 26.0 ± 3.9 kg/m² ] completed all measurements and were included in the present analysis. Lean mass characteristics (TLM, ALM, and ALM/h² ) decreased with increasing age in both men and women (P < 0.001). Men demonstrated larger absolute and relative total ALM and higher HGS and LEP compared with women at all age intervals (P < 0.001). HGS and LEP decreased progressively with age in both men and women (P < 0.01); 30 s STS performance, habitual GS, and maximal GS decreased at an accellerated rate of decline with increasing age in both men and women (P < 0.001). Habitual GS was reduced in men and women aged ≥70 years, while maximal GS was reduced from the age of ≥60 years compared with young adults (P < 0.001). Regardless of sex, 30 s STS was reduced from the age of ≥50 years compared with the young reference group (P < 0.001) CONCLUSIONS: While the power-based measurements (LEP and 30 s STS) started to decline already at age +50 years, less power-based parameters (GS and HGS) and lean mass characteristics (TLM, ALM, and ALM/h² ) remained unaltered until after the age of +70 years. Notably, the cut-off thresholds derived in the present study differed from earlier reference data, which underlines the importance of obtaining updated and local reference materials.

Keywords: Body composition; DXA; Handgrip strength; Lean mass; Leg power; Sarcopenia.

Figure 1

The association between age and total lean mass for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. TLM, total lean mass.

Figure 2

The association between age and appendicular lean mass for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. ALM, appendicular lean mass.

Figure 3

The association between age and relative total lean mass for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. TLM/h², relative total lean mass (normalized to height squared).

Figure 4

The association between age and relative appendicular lean mass for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. ALM/h², relative appendicular lean mass (normalized to height squared).

Figure 5

The association between age and handgrip strength for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. HGS, handgrip strength.

Figure 6

The association between age and leg extension power for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. LEP, leg extension power.

Figure 7

The association between age and habitual gait speed for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. GS, gait speed.

Figure 8

The association between age and maximal gait speed for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. GS, gait speed.

Figure 9

The association between age and 30 s sit‐to‐stand performance for men (A; dark grey diamonds) and women (B; white circles). Regression line (wide solid line) and 95% prediction interval (narrow solid line), T score equal to –2.0 (dashed line), data more than 2 SD below the young adult reference mean (shaded area), regression equations and adjusted R ² values are shown. STS, sit‐to‐stand.