Reliability of an alternative method to assess landing skills in adolescent surfers
Australian Strength and Conditioning Association
Faculty of Health, Engineering and Science
School of Exercise and Health Sciences/Centre for Exercise and Sports Science Research
Surfing demands a high level of physical qualities such as strength, power, and dynamic postural control to perform radical manoeuvres under control. Surfers that demonstrate great speed, power, and flow in the most critical section of wave riding will receive higher scores according to the judging criteria (1). An important feature of surfing that lacks research and needs further understanding is dynamic postural control during landing and rapid compression, which occurs during bottom turns, aerial manoeuvres and floaters etc. Paillard (2) demonstrated that higher skilled surfers possess greater postural ability compared to non-skilled surfers. However, the challenge is determining the contributing or limiting factors assessing dynamic postural control during landing in surfers. Two potentially important factors that might be critical when assessing dynamic postural control during landing are time to stabilisation and relative peak force. Time to Stabilisation (TTS) has been used to measure dynamic postural control. Dynamic postural control assessment is of great importance and might serve as a critical measurement for the sport of surfing. This method measures the ability of an athlete to transition from a dynamic movement in a controlled environment (e.g., drop and stick or jump and single leg stick on a force plate) followed by attaining a static and motionless position as quickly as possible. Furthermore, relative peak force (rPF) upon landing may quantify how effectively surfers use their muscles to attenuate eccentric load rather than allowing the force to transmit directly through the joints. For example, when landing an aerial or floater (two surfing manoeuvers), stronger surfers may have the ability to attenuate the impact force rapidly to allow them to drive out and up into the wave. Therefore, TTS and rPF are variables that might be associated with the ability to effectively attenuate eccentric load also in a dynamic environment. Various methods of TTS have been utilized to measure dynamic stability. Previous studies have addressed the reliability and precision of the TTS assessment via force plate on plyometric exercises, ACL injury, and ankle instability. Wikstrom et al. (3) have reported fair to moderate reliability of dynamic postural stability index to detect changes in three directions. Flanagan et al. (4) reported low reliability for TTS from trial to trial of the jump and landing phase of a depth jump. Goldie et al. (5) evaluated postural control via force measures and centre of pressure to quantify postural stability. They reported that force measures were better indicators of postural stability compared to centre of pressure measures. It is important to note these studies used different methods to quantify postural stability. Wikstrom (3) used a more complex single limb task to assess dynamic postural control whereas Flanagan (4) used a more traditional bilateral approach. Goldie el al. (5) had the participants stand on the force plate performing tasks with and without their eyes closed. These studies provided significant contribution to the postural stability literature; however, different methodologies will influence the results of postural stability assessment. Currently, there are no standardised methods or reference guides to assess dynamic postural control. Therefore the purpose of this study was to provide additional information on reliability measures of a novel dynamic postural control assessment via TTS and relative peak force upon landing.