ORIGINAL ARTICLE Efficacy of lower-limb muscle training modalities in severely dyspnoeic individuals with COPD and quadriceps muscle weakness: results from the DICES trial Maurice J H Sillen, 1 Frits M E Franssen, 1 Jeannet M L Delbressine, 1 Anouk W Vaes, 1 Emiel F M Wouters, 1,2 Martijn A Spruit 1 ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ thoraxjnl-2013-204388). 1 Department of Research & Education, CIRO+, Centre of Expertise for Chronic Organ Failure, Horn, The Netherlands 2 Department of Respiratory Medicine, Maastricht University Medical Centre (MUMC+), Maastricht, The Netherlands Correspondence to Maurice Sillen, Department of Research & Education, CIRO+, Centre of Expertise for Chronic Organ Failure, Hornerheide 1, Horn 6085 NM, The Netherlands; mauricesillen@ciro-horn.nl Received 21 August 2013 Revised 4 December 2013 Accepted 12 December 2013 Published Online First 7 January 2014 ▸ http://dx.doi.org/10.1136/ thoraxjnl-2014-205345 To cite: Sillen MJH, Franssen FME, Delbressine JML, et al. Thorax 2014;69:525–531. ABSTRACT Rationale Strength training and neuromuscular electrical stimulation (NMES) improve lower-limb muscle function in dyspnoeic individuals with chronic obstructive pulmonary disease (COPD). However, high-frequency NMES (HF-NMES) and strength training have never been compared head-to-head; and effects of low-frequency NMES (LF-NMES) have never been studied in COPD. Therefore, the optimal training modality to improve lower-limb muscle function, exercise performance and other patient-related outcomes in individuals with severe COPD remains unknown. Objectives To study prospectively the efficacy of HF- NMES (75 Hz), LF-NMES (15 Hz) or strength training in severely dyspnoeic individuals with COPD with quadriceps muscle weakness at baseline. Methods 120 individuals with COPD (FEV 1 : 33±1% predicted, men: 52%, age: 64.8±0.8 years) were randomised to HF-NMES, LF-NMES or strength training as part of a comprehensive inpatient pulmonary rehabilitation programme. No treadmill walking or stationary cycling was provided. Measurements and main results Groups were comparable at baseline. Quadriceps muscle strength increased after HF-NMES (+10.8 Newton-metre (Nm)) or strength training (+6.1 Nm; both p<0.01), but not after LF-NMES (+1.4 Nm; p=0.43). Quadriceps muscle endurance, exercise performance, lower-limb fat-free mass, exercise-induced symptoms of dyspnoea and fatigue improved significantly compared with baseline after HF-NMES, LF-NMES or strength training. The increase in quadriceps muscle strength and muscle endurance was greater after HF-NMES than after LF- NMES. Conclusions HF-NMES is equally effective as strength training in severely dyspnoeic individuals with COPD and muscle weakness in strengthening the quadriceps muscles and thus may be a good alternative in this particular group of patients. HF-NMES, LF-NMES and strength training were effective in improving exercise performance in severely dyspnoeic individuals with COPD and quadriceps weakness. Trial registration NTR2322 INTRODUCTION Lower-limb muscle dysfunction is a prominent extrapulmonary feature in individuals with moderate-to-very severe chronic obstructive pulmonary disease (COPD). 1 It is related to exer- cise intolerance, increased healthcare use and mor- tality. 1 Physical inactivity is most probably its main underlying cause. 1 Therefore, exercise-based pul- monary rehabilitation should be part of the inte- grated care of individuals with COPD. 2 Lower-limb muscle dysfunction occurs frequently in severely dyspnoeic individuals with COPD. 3 Therefore, there is great interest in effective rehabilitative modalities which do not evoke severe dyspnoea, such as strength training or transcutane- ous neuromuscular electrical stimulation (NMES). 2 Indeed, the metabolic load on the impaired respira- tory system is relatively low during strength training or NMES in individuals with COPD. 45 Strength training or high-frequency NMES (HF-NMES; stimulation frequencies ≥50 Hz) increases quadriceps muscle function, exercise cap- acity and health status as compared with a non- exercise control group or sham NMES in individuals with COPD, respectively. 67 To date, a head-to-head comparison of strength training and HF-NMES has not been done in severely dyspnoeic individuals with COPD. Therefore, it remains unknown whether, and to what extent, these training modalities may have similar effects in individuals with COPD. A priori, no differences were expected between the groups. Low-frequency NMES (LF-NMES, at 15 Hz) of lower-limb muscles increased exercise capacity in individuals with chronic heart failure. 8 To date, the effects of LF-NMES at 15 Hz have not been studied in individuals with COPD. However, it seems reason- able to hypothesise that quadriceps muscle endurance will improve to a greater extent after LF-NMES, 89 while quadriceps muscle strength will improve to a greater extent after HF-NMES. 10 The aim of the DICES (Dyspnoeic Individuals with COPD: Electrical stimulation or Strength training) trial was to study the efficacy of HF-NMES, LF-NMES or strength training in severely dyspnoeic individuals with COPD with quadriceps muscle weakness at baseline. METHODS Please see online supplementary data for all details. Participants Individuals with COPD referred for a pulmonary rehabilitation programme at the Centre of Sillen MJH, et al. Thorax 2014;69:525–531. doi:10.1136/thoraxjnl-2013-204388 525 Chronic obstructive pulmonary disease on June 10, 2020 by guest. Protected by copyright. http://thorax.bmj.com/ Thorax: first published as 10.1136/thoraxjnl-2013-204388 on 7 January 2014. Downloaded from