Isolated Quadriceps Training Increases Maximal Exercise Capacity in Chronic Heart Failure

Abstract

Objectives This study sought to elucidate the mechanisms responsible for the benefits of small muscle mass exercise training in patients with chronic heart failure (CHF). Background How central cardiorespiratory and/or peripheral skeletal muscle factors are altered with small muscle mass training in CHF is unknown. Methods We studied muscle structure and oxygen (O2) transport and metabolism at maximal cycle (whole body) and knee-extensor exercise (KE) (small muscle mass) in 6 healthy controls and 6 patients with CHF who then performed 8 weeks of KE training (both legs, separately) and repeated these assessments. Results Pre-training cycling and KE peak leg O2 uptake (VO2peak) were ~17% and ~15% lower, respectively, in the patients compared to controls. Structurally, KE training increased quadriceps muscle capillarity and mitochondrial density by ~21 and ~25%, respectively. Functionally, despite not altering maximal cardiac output, KE training increased maximal O2 delivery (~54%), arterial-venous O2 (a–v O2) difference (~10%), and muscle O2 diffusive conductance (DMO2) (~39%) (assessed during KE), thereby increasing single leg VO2peak by ~53%, to a level exceeding that of the untrained controls. Post-training, during maximal cycling, O2 delivery (~40%), a–v O2 difference (~15%), and DMO2 (~52%) all increased, yielding an increase in VO2peak of ~40%, matching the controls. Conclusions In the face of continued central limitations, clear improvements in muscle structure, peripheral convective and diffusive O2 transport, and subsequently O2 utilization support the efficacy of local skeletal muscle training as a powerful approach to combat exercise intolerance in CHF.

Blunted muscle angiogenic training-response in COPD patientsversussedentary controls

“…Moreover, our study indicates a probable role of the blunted muscle capillarisation response to training in the reduced V9O 2 SL improvement in the COPD patients, as angiogenesis has also shown an impact on the improvement in V9O 2 SL in two other chronic diseases: CHF [41] and peripheral arterial disease [42]. Our finding of lower improvement in the capillary-to-fibre ratio thus appears to be clinically significant.…”

Exertional dyspnoea in pulmonary arterial hypertension

“…Further studies in heart failure have demonstrated that impaired diffusional transport of oxygen may be amenable to an exercise rehabilitation programme [15], but a recent detailed assessment of the exercise haemodynamic changes following a comprehensive exercise programme did not report on these aspects [16]. Impairment of muscle flow has not been evaluated in pulmonary hypertension, but may be an additional contributing factor, as previously demonstrated in heart failure patients [15,17].…”

Exercise Training as Therapy for Heart Failure

“…Esposito and colleagues (36) have demonstrated that HF severely reduces muscle oxygen diffusion conductance (DO 2 m), helping to explain why increasing O 2 delivery to skeletal muscle via vasodilators in HF might not yield expected increases in muscle O 2 consumption during aerobic exercise (Figure 2). The impaired DO 2 m may also help account for poor muscle function and exercise intolerance in both HFrEF and HFpEF.…”