Ground reaction forces and electromyography in a parkour obstacle course : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Sport and Exercise Science at Massey University, Wellington, New Zealand

Abstract

Parkour is a physical discipline that involves athletes, also known as traceurs, using specific skills and movements to overcome obstacles in an urban environment. A typical parkour landing involves an ever-changing combination of variables such as speed, agility, and multiple movement skills that in turn may affect the forces placed on the body. The purpose of the present study was to design a field- based protocol that measured and compared the forces athletes are exposed to in their natural training environment. Methods: A parkour specific obstacle course was designed and five experienced traceurs completed the series of obstacles in succession. Between obstacle comparisons were made for ground reaction force (GRF), time to maximal ground reaction force (TTP), and rate of force development (RFD). Additionally, electromyography was assessed to help better describe underlying mechanisms associated with differences in landing forces. Electrodes were placed bilaterally on the vastus lateralis (VL), gastrocnemius (GM), and the tibialis anterior (TA) and area (%MVIC) was used to represent muscle activation. Results: GRF was highest in obstacles with larger drop heights as well as increased momentum from previous obstacles which includes obstacles 2a-floor, 4-floor, and 2c-floor. The lowest TTP values were associated with obstacles involving short landing contact time due to limited space which includes obstacles 3-4, 2c-floor, and 1-floor. RFD was greatest in obstacles 2a- floor, 3-4, 4-floor, 9-floor, and 2c-floor which all required explosive power upon landing in order to complete subsequent obstacles. EMG data showed that the GM and VL had greater activation on obstacles requiring either a change in direction such as 6b-7 and/or a rapid descent such as obstacles 7-8 and 8-floor. TA showed higher activations on obstacle 9-floor and 2b-2c, but activations were similar across most obstacles. The activation of the TA may be due to its role in eccentrically contracting during initial foot strike during landing. Conclusion: Due to the dynamic nature of parkour, athletes are often exposed to a variety of landings which would produce diverse kinetic demands. By using a parkour specific course, this study provided force data that was a close representation of the forces traceurs are exposed to in a typical parkour run.