Author(s): BARBOUR, D., ALLEN, S.J.1, JOHNSTON, M.2, FOLLAND, J.P.1, Institution: LOUGHBOROUGH UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 2512

INTRODUCTION:
Sprinting and jumping ability are paramount to performance in many track and field events, with variations widely implemented in training and rehabilitation programs. Knowledge of lower limb neuromechanical function may assist in understanding sprinting and jumping performance as well as informing training, testing, and injury prevention strategies. Although sprint and jump tasks have significant plantar flexor (PF) involvement, whether differences in PF kinetics contribute to performance differences between high performing jump / sprint athletes and untrained controls is unknown (1,2). The current study aimed to compare ankle joint PF kinetics between recreationally active (RA) and high performing sprint / jump athletes (HP) during jumping and sprinting tasks.
METHODS:
Twenty-four healthy young adults (RA, n=12; HP, n=12) participated in this study with ethical approval and completed isometric maximal voluntary contractions (iMVC) of the PF followed by counter movement jumps (CMJ), drop jumps (DJ), and twenty-two-meter sprints (SP). Motion data was captured using an eighteen camera, 3-dimensional motion capture system (Vicon Motion Systems Ltd, UK) while ground reaction forces were measured using portable and imbedded force plates (Kistler Instrumental AG, Winterhur, Switzerland). Neuromuscular activity of the triceps-surae (TS) was recorded from four sEMG sensors (Trigno mini sensors, Delsys Europe, Sale, UK) over the TS muscles of each leg. Modelling software (Visual3D, C-motion Inc, Maryland, USA) and inverse dynamics was used to calculate, peak positive power, peak moment and positive work relative to body mass around the ankle joint of both legs during the stance phase of each task. 
RESULTS:
The HP group achieved significantly higher performance measures in all tasks compared to RA (isometric strength: p = 0.01, + 20.8 %; CMJ jump height: p = 0.03, + 20.0 %; DJ jump height p = 0.01, + 28.1 %; SP speed p = 0.04, + 9.1 %). During the CMJ and SP no between group differences were found for PF peak positive power (CMJ: p = 0.10, SP: p = 0.33), positive work (CMJ: p = 0.23, SP: p = 0.51), or peak moment (CMJ: p = 0.08, SP: p = 0.45). The HP group (1.60 ± 0.27 J/kg) did significantly greater positive work at the ankle during DJ when compared to RA (1.37 ± 0.18 J/kg, p = 0.02) although no differences were found in peak positive power or peak moment.
CONCLUSION:
PF kinetics at the ankle joint do not seem to explain superior CMJ or SP performance of high-performing sprint / jump athletes compared to recreationally active individuals and may suggest that hip and knee joint kinetics largely account for the group differences in these tasks. Greater positive work around the ankle in the HP group (vs RA) during the DJ, but not other tasks, may be due to a higher demand on the PF during a DJ with less involvement of knee and hip joints.

1. Schache et al., JExpBio, 2015
2. Sugisaki et al., JSportScienes, 2012