Impact attenuation and variability during running in females: a lifespan investigation.

CONTEXT Impact is known to cause injury during running, while variability is thought to promote healthy performance. OBJECTIVE Quantify contributions of the lower extremity and back and the variability of impact generation among (1) prepubescent girls (Grp 1), (2) normally menstruating women (Grp 2), and (3) postmenopausal women (Grp 3) to address possible lifespan changes during running. DESIGN A mixed model experiment. SETTING Biomechanics Laboratory. PARTICIPANTS 31 healthy females owing membership to Grp1, Grp 2, or Grp 3. INTERVENTION Participants ran on a treadmill at their preferred speed (45 s) and at a speed 10% faster (45 s) while instrumented with uniaxial accelerometers. MAIN OUTCOME MEASURES Lower extremity attenuation, back attenuation and variability of peak impact acceleration values. RESULTS Lower extremity attenuation and variability were greatest for Grp 1 while impact variability was least for Grp 2. CONCLUSION Lifespan phases appear to affect impact attenuation strategies and variability of impact during running for females.