An important feature of patients with HFpEF is impaired exercise tolerance, resulting in worsening and reduced quality of life. Studies in the literature on patients with HFpEF suggest that the limited transport of oxygen to the muscles can be one factor leading to the early development of fatigue during physical activity and reduced effort tolerance. A recent study also shows that patients with HFpEF have an increased susceptibility to both central and peripheral fatigue, suggesting that neuromuscular fatigue may be one of the main mechanisms limiting exercise in this population. Type 2 diabetes mellitus (T2DM), which affects 90-95% of diabetic patients, is a comorbidity of particular interest in heart failure (HF). In T2DM, as in HF, some observed an altered energy metabolism of the muscle and a shift in the type of muscle fibers. Hyperglycemia influences neuromuscular function and appeared to be one of the major causes of oxidative stress by affecting the intrinsic properties of the muscle (mitochondrial activity and function, myofilaments) related to the expression of force. The impact of diabetes on neuromuscular function is also linked to long-term complications such as diabetic peripheral neuropathy involving impairment of motor nerve conduction and vascular complications. This opens up a rather complex picture suggesting that T2DM in patients with HF could contribute to a further decline in muscle strength by further reducing the aerobic capacity of these patients. It seems, there are currently no studies in the literature evaluating how much the coexistence of T2DM impacts neuromuscular fatigue and strength in patients with HF. Thus, the primary aim of this study will be to evaluate the differences in central and peripheral neuromuscular fatigue - determined by a submaximal exercise protocol with intermittent isometric contractions - in two groups of patients with heart failure with preserved ejection fraction with or without type 2 diabetes mellitus. Secondary outcomes will be related to the investigation of the differences in NO-mediated vascular function induced by a single passive movement of the leg, in the energy cost of walking, and in muscle oxygenation between the two groups.
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Change of the isometric force
Timeframe: baseline and up to 1400 secs