Date of Award

2015

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Exercise and Health Sciences

Faculty

Faculty of Health, Engineering and Science

First Advisor

Dr Jeremy Sheppard

Second Advisor

Dr Sophia Nimphius

Third Advisor

Professor Robert Newton

Abstract

Competitive surfing involves highXrisk manoeuvres that may impose injury risk, especially in the lower extremity. Although the dynamic environment of surfing is a major factor of unpredictable determinants for injury risk, there may be athlete qualities with importance for prevention. Previous studies suggest that dynamic loading and landing tasks represent major risk factors, and should therefore be included in athlete assessments and risk analysis.

The purpose of this thesis was to investigate landing tasks that may be related to surfing performance and injury risk. It involved studying manoeuvres and landing tasks to establish its relevance for surfing athletes, develop multifactorial assessment protocols, as well as observe mechanisms and factors influencing lower extremity injury risk in high performance surfing.

Study 1 examined manoeuvres of the competitive season of the World Championship Tour, reporting on frequency and scores. Although reXentries were the most common manoeuvres, waves including aerial manoeuvres and tube rides scored higher on average; 7.40 ± 1.53 and ± 6.82 ± 2.13 respectively, compared to 5.03 ± 2.21 for turning manoeuvre waves. Therefore, aerial manoeuvres and barrel rides are necessary for high performance surfing

Study 2 evaluated impact forces, accelerations and dorsiflexion range of motion in five different landing tasks. A drop and stick landing, two surf stance landings and two gymnastic type landings were performed by eleven competitive athletes. The peak acceleration was about 50% higher whilst landing on a board in a miniXtrampoline gymnastic exercise compared to a surf stance landing from a 50 cm box (p≤0.05). Furthermore, the dorsiflexion ranges of motion in the gymnastic type landings were lower than the other landing types (p≤0.05). The greater load observed in the more complex tasks indicate that the risk involved may be higher in these, compared to general landing tasks.

Study 3 provided information of the circumstances of surfing injuries, by video analysis (N=13). Factors that were found to distinguish between injury situations and non-injury

situations were deep knee flexion at water contact, upper body lateral displacement, knee valgus, perturbations in the landing and direction of board relative riding direction. For safety, athletes should practice landing competency and increase adaptability to sudden environmental changes.

Study 4 describes the development of a model based on the five measures ankle dorsiflexion range of motion, lower body strength, and time to stabilisation, peak force and a frontal plane video analysis during a drop and stick landing. The model was based on normative data from 71 surfing athletes and developed into a score based on exponential functions for four groups of athletes (male, female, junior and senior). It was concluded easy to implement, and may be useful in the assessment of landing competency of surfing athletes.

Study 5 was a prospective study of competitive surfing athletes, observing injuries during six months. Furthermore, the athletes (N=48) were tested on baseline assessments to reveal whether any of the variables could be useful as indicator of injury risk from closed kinetic chain movements. There were 22 injuries reported during the period, whereof 8 were categorised closed kinetic chain injuries. Two baseline measures were found to be potential risk factors; the model of landing qualities and bilateral squat asymmetry (p≤0.05). Athletes with excessively poor assessment results on landings and bilateral squat may be alerted of potential injury risk. Landing competency and other bilateral movements can be tested and trained in the land-based preparation of surfing athletes, and seem to be relevant for competitive surfing athletes. If excessively poor scores on these assessments expose the athlete to injury risk, then athletes should aim for satisfactory scores before successively training high-risk manoeuvres in the surfing context.

Comments

Online access available but restricted access to chapters 3-7 by author's request

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