Calf raise exercise increases walking performance in patients with intermittent claudication.

Area of Science:

• Exercise physiology
• Mitochondrial biology
• Vascular medicine

Background:

• Intermittent claudication (IC) symptoms are often improved by exercise.
• Exercise benefits may stem from increased blood flow or enhanced muscle mitochondrial capacity.
• Preconditioning (ischemia-reperfusion) stimulates mitochondria.

Purpose of the Study:

• To investigate if calf raise exercise improves walking performance and mitochondrial capacity in IC patients.
• To determine if calf raise exercise alters blood flow in IC patients.
• To test the hypothesis that 8 weeks of calf raise exercise increases walking performance and mitochondrial capacity without changing blood flow.

Main Methods:

• Randomized controlled trial comparing calf raise exercise (n=14) to traditional walking exercise (n=15) for 8 weeks.
• Participants performed exercises unsupervised, three times daily (calf raise) or three times weekly (walking).
• Outcomes included walking performance, mitochondrial capacity, peak oxygen uptake, hemodynamics, and quality of life, measured pre- and post-intervention.

Main Results:

• The calf raise group showed significant improvements in pain-free walking distance (+44m), maximal walking distance (+99m), claudication onset time (+123s), and peak walking time (+104s).
• Calf raise exercise increased citrate synthase activity, a marker of mitochondrial volume-density, in calf muscles (P=.02).
• No significant changes were observed in maximal blood flow, peak oxygen uptake, or mitochondrial respiration in either group. The calf raise group also reported reduced disease anxiety.

Conclusions:

• Calf raise exercise effectively improves walking performance in patients with intermittent claudication.
• This exercise modality enhances mitochondrial volume-density in the gastrocnemius muscle.
• The benefits of calf raise exercise on walking performance occur without a significant increase in muscle blood flow.