This study examined the influence of 12 different synthetic sport surfaces (bitumen, concrete, 3 samples of synthetic grass, and 7 samples of rubber surfaces) on ground reaction forces at landing in netball. Ground reaction force data were obtained for 10 skilled netball players at landing after performing a typical attacking netball movement pattern. Force–time histories of the maximum peak vertical ground reaction forces (VGRF), the initial peak VGRF, and peak braking forces were determined for each trial. Results of the a priori planned comparison analysis indicated that subjects demonstrated significantly longer time to maximum peak VGRF and initial peak VGRF when landing on grass, higher peak braking forces when landing on bitumen and concrete combined, and a significantly shorter time to peak braking force when landing on grass in comparison to other samples tested. It was concluded that the rubber surfaces tested demonstrated the potential for being the most suitable playing surface for minimization of injuries in netball.
Julie R. Steele and Peter D. Milburn
Jodie E. Southall, Anthony D. Okely, and Julie R. Steele
This study compared actual and perceived physical competence of overweight and nonoverweight children. Participants were 109 nonoverweight and 33 overweight Grade 5 and 6 children (mean age 10.8 years). Overweight status was determined using age- and gender-specific international body-mass-index cut-off values. Actual competence was assessed using the Test of Gross Motor Development, 2nd ed., and perceived competence was assessed using an expanded version of the Athletic Competence subscale of the Self-Perception Profile for Children (SPPC). Overweight children had significantly lower actual and perceived physical competence. When actual competence was partitioned into locomotor and object-control skills, however, differences only existed for locomotor skills. These findings indicate that low actual and perceived physical competence might be important contributing factors in maintaining childhood obesity. Interventions to improve actual and perceived physical competence in overweight children should provide opportunities to learn and master fundamental movement skills in an environment where parents, teachers, and coaches provide positive and specific feedback, encouragement, and modeling.
Alasdair R. Dempsey, Bruce C. Elliott, Bridget J. Munro, Julie R. Steele, and David G. Lloyd
Anterior cruciate ligament (ACL) injuries are costly. Sidestep technique training reduces knee moments that load the ACL. This study examined whether landing technique training alters knee moments. Nineteen team sport athletes completed the study. Motion analysis and ground reaction forces were recorded before and after 6 weeks of technique modification. An inverse dynamic model was used to calculate three-dimensional knee loading. Pre- and postintervention scores were compared using paired t tests. Maximal knee flexion angle during landing was increased following training. There was no change in valgus or flexion moments, but an increase in peak internal rotation moment. This increase in internal rotation moment may increase the risk of ACL injury. However, the increased angle at which the peak internal rotation moment occurred at follow up may mitigate any increase in injury risk by reducing load transmission.
James R. Forsyth, Ryan de la Harpe, Diane L. Riddiford-Harland, John W. Whitting, and Julie R. Steele
To investigate the influence of turns, tube rides, and aerial maneuvers on the scores awarded in elite men’s professional surfing competitions. The successful completion rate and scores associated with different aerial variations were also investigated.
Video recordings from all 11 events of the 2015 World Surf League men’s world championship tour were viewed to classify maneuvers performed by the competitors on each wave as turns, tube rides, and aerials. A 2-way ANOVA was used to determine any main effect or interaction of maneuver type or event location on the wave scores. A 1-way ANOVA was used to determine any main effect of aerial type on successful completion rate.
Aerial maneuvers were scored significantly higher than tube rides and turns. A significant main effect existed for maneuver and completion rate. Aerial maneuvers had the lowest completion rate, 45.4%. During the finals series (quarterfinals, semifinals, and finals heats) aerial-maneuver completion rate was higher, 55.4%. The frontside air reverse was the most commonly performed maneuver and received an average score of 6.77 out of 10.
Professional surfers can optimize their potential single-wave scores during competition by successfully completing aerial maneuvers. However, aerial maneuvers continue to be a high-risk maneuver with a significantly lower completion rate. Our findings suggest that surfers should aim to improve their aerial-maneuver completion rate via surf practice or land-based training drills.
Lina E. Lundgren, Tai T. Tran, Sophia Nimphius, Ellen Raymond, Josh L. Secomb, Oliver R.L. Farley, Robert U. Newton, Julie R. Steele, and Jeremy M. Sheppard
To develop and evaluate a multifactorial model based on landing performance to estimate injury risk for surfing athletes.
Five measures were collected from 78 competitive surfing athletes and used to create a model to serve as a screening tool for landing tasks and potential injury risk. In the second part of the study, the model was evaluated using junior surfing athletes (n = 32) with a longitudinal follow-up of their injuries over 26 wk. Two models were compared based on the collected data, and magnitude-based inferences were applied to determine the likelihood of differences between injured and noninjured groups.
The study resulted in a model based on 5 measures—ankle-dorsiflexion range of motion, isometric midthigh-pull lower-body strength, time to stabilization during a drop-and-stick (DS) landing, relative peak force during a DS landing, and frontal-plane DS-landing video analysis—for male and female professional surfers and male and female junior surfers. Evaluation of the model showed that a scaled probability score was more likely to detect injuries in junior surfing athletes and reported a correlation of r = .66, P = .001, with a model of equal variable importance. The injured (n = 7) surfers had a lower probability score (0.18 ± 0.16) than the noninjured group (n = 25, 0.36 ± 0.15), with 98% likelihood, Cohen d = 1.04.
The proposed model seems sensitive and easy to implement and interpret. Further research is recommended to show full validity for potential adaptations for other sports.