Despite reductions in muscle mass and muscle strength in adults with CHD, the muscle strength per muscle mass relationship does not differ from controls

Abstract

Background: Patients with CHD exhibit reduced isometric muscle strength and muscle mass; however, little is known how these parameters relate. Therefore, the aim was to investigate the relation between isometric limb muscle strength and muscle mass for patients in comparison to age- and sex-matched control subjects. Methods: Seventy-four patients (35.6 ± 14.3 years, women n = 22) and 74 matched controls were included. Isometric muscle strength in elbow flexion, knee extension, and hand grip was assessed using dynamometers. Lean mass, reflecting skeletal muscle mass, in the arms and legs was assessed with dual-energy x-ray absorptiometry. Results: Compared to controls, patients had lower muscle strength in elbow flexion, knee extension, and hand grip, and lower muscle mass in the arms (6.6 ± 1.8 kg versus 5.8 ± 1.7 kg, p < 0.001) and legs (18.4 ± 3.5 kg versus 15.9 ± 3.2 kg, p < 0.001). There was no difference in achieved muscle force per unit muscle mass in patients compared to controls (elbow flexion 0.03 ± 0.004 versus 0.03 ± 0.005 N/g, p = 0.5; grip strength 0.008 ± 0.001 versus 0.008 ± 0.001 N/g, p = 0.7; knee extension 0.027 ± 0.06 versus 0.028 ± 0.06 N/g, p = 0.5). For both groups, muscle mass in the arms correlated strongly with muscle strength in elbow flexion (patients r = 0.86, controls, r = 0.89), hand grip (patients, r = 0.84, controls, r = 0.81), and muscle mass in the leg to knee extension (patients r = 0.64, controls r = 0.68). Conclusion: The relationship between isometric muscle strength and limb muscle mass in adults with CHD indicates that the skeletal muscles have the same efficiency as in healthy controls.