Functional electrical stimulation improves muscle strength and endurance in patients after cardiac surgery: a randomized controlled trial

BACKGROUND: Functional electrical stimulation (FES) has shown benefits in patients with chronic heart failure. Therefore, it is possible that FES can benefit patients similarly after cardiac surgery. OBJECTIVE: This randomized placebo-controlled trial aimed to evaluate the effects of FES on lower limb functional capacity, strength, endurance, and muscle mass after discharge from cardiac surgery. METHODS: Twenty patients were allocated (1:1) to the group receiving FES to the quadriceps (FESG) or FES placebo (FESPG). FES was applied at a frequency of 15 Hz, with 0.5 ms pulse width, 5 s contraction time, and 10 s resting time, twice a week for 40 min over a period of eight weeks. Functional capacity was assessed using the six-minute walk test (6MWT), lower limb muscle strength using the one repetition maximum test (1RM), endurance using the sit-and-stand test (SST), and muscle using the perimeter of the thighs. RESULTS: Both groups increased the distance covered in the 6MWT (FESG: 49.6 m, 95% CI 15.9–83.3; FESPG: 41.5 m, 95% CI 7.8–75.2), but without a difference between groups. There were significant between-group differences for quadriceps muscle strength (7.2 kg, 95% CI 0.2–14.2) and muscle endurance (2.2 repetitions, 95% CI 1.0–3.4) in favor of the FESG. CONCLUSION: FES improves lower limb muscle strength and endurance in patients after cardiac surgery. Larger trials are needed to confirm our findings.