Aging of running shoes and its effect on mechanical and biomechanical variables: implications for runners.
Chambon, Nicolas; Sevrez, Violaine; Ly, Quoc Hung; Guéguen, Nils; Berton, Eric; Rao, Guillaume, Journal of Sports Sciences Jul2014, Vol. 32 Issue 11, p1013
Abstract: This study investigates the effect of running shoes’ aging on mechanical and biomechanical parameters as a function of midsole materials (viscous, intermediate, elastic) and ground inclination. To this aim, heel area of the shoe (under calcaneal tuberosity) was first mechanically aged at realistic frequency and impact magnitudes based on a 660 km training plan. Stiffness (ST) and viscosity were then measured on both aged and matching new shoes, and repercussions on biomechanical variables (joint kinematics, muscular pre-activation, vertical ground reaction force and tibial acceleration) were assessed during a leg-extended stepping-down task designed to mimic the characteristics of running impacts. Shoes’ aging led to increased ST (means: from 127 to 154 N ∙ mm−1) and decreased energy dissipation (viscosity) (means: from 2.19 to 1.88 J). The effects induced by mechanical changes on body kinematics were very small. However, they led with the elastic shoe to increased vastus lateralis pre-activation, tibial acceleration peak (means: from 4.5 g to 5.2 g) and rate. Among the three shoes tested, the shoe with intermediate midsole foam provided the best compromise between viscosity and elasticity. The optimum balance remains to be found for the design of shoes regarding at once cushioning, durability and injury prevention.
Effectiveness of post-match recovery strategies in rugby players
Objectives: To examine the effectiveness of four interventions on the rate and magnitude of muscle damage recovery, as measured by creatine kinase (CK).
Methods: 23 elite male rugby players were monitored transdermally before, immediately after, 36 hours after, and 84 hours after competitive rugby matches. Players were randomly assigned to complete one of four post-match strategies: contrast water therapy (CWT), compression garment (GAR), low intensity active exercise (ACT), and passive recovery (PAS).
Results: Significant increases in CK activity in transdermal exudate were observed as a result of the rugby match (p<0.01). The magnitude of recovery in the PAS intervention was significantly worse than in the ACT, CWT, and GAR interventions at the 36 and 84 hour time points (p<0.05).
Conclusions: An enhanced rate and magnitude of recovery was observed in the ACT, CWT, and GAR treatment groups when compared with the PAS group. Low impact exercise immediately post-competition, wearing compression garments, or carrying out contrast water therapy enhanced CK clearance more than passive recovery in young male athletes.