Efficacy of lower-limb muscle training modalities in severely dyspnoeic individuals with COPD and quadriceps muscle weakness: response from the authors. Issue 10 (13th June 2014) - Sillen, Maurice J H; Franssen, Frits M E; Delbressine, Jeannet M L; Vaes, Anouk W; Wouters, Emiel F M; Spruit, Martijn A