Haemodialysis (HD) patients are characterized by muscle wasting and consequently decreased physical functioning and poor outcome. This pilot study investigated if a novel intradialytic exercise programme could increase lean mass via up-regulation of the insulin-like growth factor (IGF) system. Nine HD patients were assessed before (w-12) and after a 3-month control phase (w0), after a three-month intradialytic interval training programme using high intensity cycle exercise (w12), and after a withdrawal of treatment phase (w24). Body composition was determined by dual energy X-ray absorptiometry (DEXA) and bioelectrical impedance spectroscopy (BIS); physical functioning by knee extensor strength (KES) and 30-s sit stand test (SST); and IGF-I and IGFBP-3 in serum and muscle by radioimmunoassay. Despite significant increases in training load (+274%, P<0·001), peak power output (+71%, P<0·001) and physical function (KES: +19%, P<0·05; SST: +20%, P<0·05) following the intervention phase, lean masses by DEXA, intra cellular water by BIS (a surrogate measure of body cell mass) and serum and muscle IGFs remained unchanged following training. Although this novel exercise programme, utilizing high intensity interval training, was safe, clinically feasible and beneficial in terms of physical functioning, the 12 weeks of intradialytic cycle exercise failed to reverse the muscle atrophy characteristic of this population. Future studies, using primary outcome measures similar to those employed in the present study, should investigate other anabolic interventions to determine potential treatments for the muscle wasting associated with end stage renal disease.