Nordic walking with an integrated resistance shock absorber affects the femur strength and muscles torques in postmenopausal women

Deterioration of the structure and function of the musculoskeletal system represents a significant problem during aging and intervention with a suitable load of physical activity may improve the quality of life. Nordic walking (NW) has become a popular and easily accessible form of activity, especially for older adults people around the world. Thus, the purpose of the study was to evaluate the influence of an Nordic walking training program with classic poles (NW) and with integrated resistance shock absorber (RSA) on bone mineral density and the peak torques of upper limb muscles and to compare the effects of both intervention programs. 25 women were randomly assigned to two training groups: 10 subjects using RSA (68 ± 4.19 years) and 15 subjects using NW poles (65 ± 3.40 years), which completed 8 weeks of training program. The hip, spine and forearm areal bone mineral density, torques of the flexors and extensors at the elbow and shoulder joints were measured before starting the training programs and after their completion. The most significant effect was found in differences between the two groups of women with respect to the femur strength index (p = 0.047) and the ratio of the flexors to extensors in the elbow (p = 0.049) and shoulder (p = 0.001) joints and peak torque of flexors in the shoulder joint (p = 0.001) for the left arm. A significant difference was also found in the index of torque asymmetry of flexors in the shoulder joint (p = 0.002). The study shows that Nordic walking with RSA poles for postmenopausal women led to beneficial changes in the femur strength index. However, we found no significant influence on bone mineral density values measured on the whole body, the femoral neck, forearm or lumbar spine regions. The occurrence of asymmetry in biomechanical muscle parameters, which was observed using RSA poles, may suggest the necessity of systematic controlling the gait technique to avoid the adverse consequences of asymmetrical rotation of the lumbar spine.