Is the soleus a sentinel muscle for impaired aerobic capacity in heart failure?

PURPOSE: Skeletal muscle wasting is well documented in chronic heart failure (CHF). This paper provides a more detailed understanding of the morphology behind this muscle wasting and the relationship between muscle morphology, strength and exercise capacity in CHF. We investigated the impact of CHF on lower limb lean mass, detailed muscle-tendon architecture of the individual triceps surae muscles (soleus, SOL; medial gastrocnemius, MG and lateral gastrocnemius, LG) and how these parameters relate to exercise capacity and strength. METHODS: 11 CHF patients and 15 age-matched controls were recruited. Lower limb lean mass was assessed by dual energy X-ray absorptiometry (DXA) and the architecture of skeletal muscle and tendon properties by ultrasound. Plantarflexor strength was assessed by dynamometry. RESULTS: Patients with CHF exhibited ∼25% lower combined triceps surae volume and physiological cross-sectional area (PCSA) compared to control subjects (p < 0.05), driven in large part by reductions in the SOL. Only the SOL volume and the SOL and MG PCSA were statistically different between groups after normalizing to lean body mass and body surface area, respectively. Total lower limb lean mass did not differ between CHF and control subjects, further highlighting the SOL specificity of muscle wasting in CHF. Moreover, the volume of the SOL and plantarflexor strength correlated strongly with peak oxygen uptake (V ̇O2 peak) in patients with CHF. CONCLUSIONS: These findings suggest that the SOL may be a sentinel skeletal muscle in CHF and provide a rationale for including plantarflexor muscle training in CHF care