Spring-Mass Behaviour during the Run of an International Triathlon Competition

Description

We investigated the changes in step temporalparameters and spring-mass behaviour duringthe running phase of a major internationaltriathlon competition. 73 elite triathletes werefollowed during the 2011 World ChampionshipsGrand Final. The running speed, groundcontact and fl ight times were assessed over a30 m fl at section at the beginning of the 4 runninglaps and towards the fi nish line, by usinga high-frequency camera (300 Hz). The leg andvertical stiff ness, and vertical displacement ofthe mass centre were calculated from step temporalcharacteristics. A concomitant decreasein running speed, vertical stiff ness and leg stiff -ness was reported during the four running laps,except towards the fi nish line, where theseparameters increased. Running biomechanicswas not aff ected between the beginningand the end of the 10 km run, when triathleteswere compared for the same running speed(1.68 ± 0.16 m vs. 1.70 ± 0.17 m for step length,3.18 ± 0.11 Hz vs. 3.16 ± 0.15 Hz for step rate,12.87 ± 3.14 kN.m − 1 vs.12.76 ± 3.05 kN.m − 1 forKleg, 31.18 ± 4.71 kN.m − 1 vs.30.74 ± 3.88 kN.m − 1for Kvert, at lap1 and fi nish, respectively). Independentof the cofounding eff ect of speed anddespite the neuromuscular fatigue previouslyshown after a long-duration event, the lowerlimb mechanical stiff ness and the overall springmassregulation were not altered over the 10 kmtriathlon run in elite competitors. This studyshowed also that step length explained, to agreater extent than step frequency, the runningspeed variance in elite triathletes.

Abstract

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