Benefits of neuromuscular electrical stimulation prior to endurance training in patients with cystic fibrosis and severe pulmonary dysfunction

Abstract

Background: We investigated the effect of neuromuscular electrical stimulation (NMES) training prior to endurance training in patients with cystic fibrosis (CF) and severe pulmonary obstruction.

Methods: Fourteen patients with CF (FEV(1) = 35% ± 11% predicted) were prospectively randomized to either a 6-week NMES training program (n = 7) or a 6-week control period (n = 7) both followed by ergocycle (ERGO) training (8 weeks) (NMES + ERGO and control + ERGO groups). Measurements were pulmonary function, mid-thigh circumference, quadriceps strength, 6-min walk distance, maximal exercise capacity on a cycloergometer, plasma biomarkers, insulin resistance (homeostasis model assessment indexes), and quality of life (CF questionnaire for adults and teenagers > 14 years of age [CFQ14 + ], Baseline Dyspnea Index-Transition Dyspnea Index).

Results: NMES + ERGO training greatly improved mid-thigh circumference ( + 2.6 ± 0.9 cm vs - 0.4 ± 1.4 cm), quadriceps strength ( + 6 ± 5 kg vs - 2 ± 2 kg), and BMI ( + 0.6 ± 0.6 kg/m(2) vs - 0.5 ± 0.7 kg/m(2) ) compared with control + ERGO training ( P < .05). No differences between groups were found in exercise-induced changes in 6-min walk distance and maximal exercise capacity. However, dyspnea after the 6-minute walk test, the fasting glucose/insulin ratio (calculated as an index of insulin resistance), and physical function and health perception domains of the CFQ14 + improved after NMES + ERGO training compared with control + ERGO training ( P < .05). Significant correlations were found between changes in mid-thigh circumference and muscle strength, ventilation requirements during exercise, insulin sensibility, and the physical function section of CFQ14 + ( P < .05).

Conclusions: NMES training performed prior to endurance training is useful for strengthening peripheral muscles, which in turn may augment gains in body weight and quality of life, further reductions in ventilation requirements during exercise, and retard insulin resistance in patients with CF with severe pulmonary obstruction.

Trial registration: ClinicalTrials.gov NCT00391703.