Mitochondrial capacity, muscle endurance, and low energy in friedreich ataxia


Introduction: In this study we noninvasively evaluated skeletal muscle mitochondrial capacity, muscle-specific endurance, and energy/fatigue feelings in persons with Friedreich ataxia (FRDA) and able-bodied controls (AB). Methods: Forearm mitochondrial capacity was measured in FRDA (n = 16) and AB (n = 10) study participants using the rate of recovery of oxygen consumption after electrical stimulation with near-infrared spectroscopy. Mechanomyography (MMG) assessed muscle endurance after electrical stimulation for 3 minutes at 2 Hz, 4 Hz, and 6 Hz. Validated scales assessed disease severity and energy/fatigue feelings. Results: Groups did not differ in mitochondrial capacity (FRDA and AB: 1.8 ± 0.3 L/min). The difference in muscle endurance at 6 Hz was lower by 19.2% in the FRDA group (group effect: P < 0.001). Feelings of physical energy were 34% lower in FRDA group. In FDRA muscle, endurance was positively related to mitochondrial capacity (r = 0.59, P = 0.03), and disease severity was negatively related to mitochondrial capacity (r = –0.55, P = 0.04) and muscle endurance (r = –0.60, P = 0.01). Conclusion: Non-invasive measures of skeletal muscle mitochondrial capacity and muscle-specific endurance are useful in monitoring FRDA. Muscle Nerve 56: 773–779, 2017.

Muscle and Nerve