SUMMARY: A 28-week resistance training with linear periodization was compared with an undulating model in 27 premenopausal women. In both groups, bone mineral density (BMD) was not changed but muscle strength increased, and there were changes in anthropometrical and muscle damage parameters, indicating that in this population, these models are similar concerning these variables. INTRODUCTION: This study seeks to compare the effects of resistance training with undulating versus linear periodization on BMD, muscle strength, anthropometrical variables, and muscle damage parameters in premenopausal women. METHODS: Twenty-seven females (39.6 +/- 0.41 years, mean +/- standard error), without osteopenia or osteoporosis and without calcium supplementation, were randomly assigned either to a linear periodization group (LPG, n = 14) or to an undulating periodization group (UPG, n = 13). The subjects were trained three times a week for 28 weeks. Lumbar spine and femoral neck BMDs were measured through dual-energy X-ray absorptiometry. Maximal and submaximal dynamic muscle strengths were measured through the 1-RM and 20-RM tests, respectively. Anthropometrical (body mass, skinfolds, and perimeters) and muscle damage parameters were assessed through serum creatine kinase (CK) and delayed-onset muscle soreness (DOMS). RESULTS: BMD remained unchanged in both groups, despite significant increases in maximal (LPG, 37-73%; UPG, 40-70%) and submaximal (LPG, 82-114%; UPG, 70-102%) muscle strength. The perimeter of the distal thigh was increased (about 1.7 cm) in both groups. CK and DOMS were greater in the first mesocycle than in the subsequent ones. After the 1st training session in each mesocycle, 24 and 48 h CK was increased as compared to pretraining values. CONCLUSIONS: The resistance training of 28 weeks increased muscle strength in both training groups with no difference in BMD or in the occurrence of muscle damage.