Effects of various midsole densities of basketball shoes on impact attenuation during landing activities.

The purpose of this study was to examine effects of shoe midsole densities and mechanical demands (landing heights) on impact shock attenuation and lower extremity biomechanics during a landing activity. Nine healthy male college athletes performed 5 trials of step-off landing in each of 9 test conditions, i.e., a combination of landings in shoes of 3 midsole densities (soft, normal, hard) from each of 3 landing potential energy (PE) levels (low, median, high). Ground reaction forces (GRF), accelerations (ACC) of the tibia and forehead, and sagittal kinematic data were sampled simultaneously. A 3 x 3 two-way (surface x height) repeated-measures analysis of variance (ANOVA) was performed on selected kinematic, ACC, and GRF variables; a 3 x 3 x 3 three-way (surface x height x joint) ANOVA was performed on variables related to eccentric muscular work. The GRF results showed that the forefoot peak GRF in the normal and hard midsoles was significantly greater than the soft midsole at the low and median PEs. Rearfoot peak GRF was significantly greater for the hard midsole than for the soft and normal midsoles at the median and high PEs, respectively. The peak head and tibia peak ACC were also attenuated in similar fashion. Kinematic variables did not vary significantly across different midsoles, nor did energy absorbed through lower extremity extensors in response to the increased shoe stiffness. Knee joint extensors were shown to be dominant in attenuating the forefoot impact force across the landing heights. The results showed limited evidence of impact-attenuating benefits of the soft midsole in the basketball shoes.