['Is weight-training exercise intervention harmful to women with or at risk of breast cancer-related lymphoedema?', 'Systematic review with meta-analysis of randomised trials.', 'Women with or at risk of breast cancer-related lymphoedema.', 'Progressive weight-training exercise.', 'The primary outcomes were severity (volume difference) and incidence of arm lymphoedema. Secondary outcomes included muscle strength of the upper and lower limbs, quality of life and body mass index.', 'Eleven studies from eight trials involving 1091 women were included. Weight-training exercise of low to moderate intensity with relatively slow progression significantly improved the upper limb strength (SMD 0.93, 95% CI 0.73 to 1.12) and lower limb strength (SMD 0.75, 95% CI 0.47 to 1.04) without increasing the arm volume (SMD -0.09, 95% CI -0.23 to 0.05) or incidence of breast cancer-related lymphoedema (RR 0.77, 95% CI 0.52 to 1.15). No significant effects were noted for body mass index (SMD -0.10, 95% -0.31 to 0.11). Some aspects of quality of life may improve with weight training. PARTICIPANTS in all trials used pressure garments and received supervision; no trials used high-intensity weight training.'] Is weight training harmful for women with breast cancer-related lymphoedema : a systematic review?