Ground reaction force profiles of specific jump-landing tasks in females: development of a systematic and progressive jump-landing model
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During dynamic fast paced sports, such as netball, volleyball and basketball the body is exposed to high ground reaction forces (GRF), contributing to lower body injury occurrence during landing. A certain amount of conditioning and/or technique training to effectively mitigate injury risk and improve performance is particularly important amongst a female population. Therefore the initial aim of this thesis was to systematically review the literature on jump-landing progressions. This incorporated an in-depth discussion of the prerequisite factors which were thought critical when progressing jump-landing stimuli during training. Following the review of literature a systematic model aimed at progressing jump-landing proficiency was presented, which targeted training components for effective program implementation. This model addressed the issues of incorrect landing technique, insufficient muscular strength and lack of balance and neuromuscular control. Each of these concerns are integrated into specific phases and training components aimed at progressively overloading the subject during landing. Understanding the magnitude of the GRF associated with various jump-landing patterns was the aim for the final part of this thesis. Presented as a cross sectional experimental study, this section quantified the GRFs experienced during progressive drop-landing tasks. This study informed the exercise prescription for Phase 2 of the training model developed in the previous chapter. Twenty-one netball players from the National Talent Development squad volunteered to participate in a study to quantify the vertical (VGRF), horizontal (HGRF) and lateral (LGRF) GRFs when jump height and distance were systematically increased across bilateral and unilateral landings. Three different heights (15, 30 and 45 cm), distances (40, 80 and 120 cm) and landing strategies (bilateral forward, unilateral forward and unilateral lateral) were used to create 27 jump-landing conditions. Two-way analysis of variance was used to analyse the effects of drop height and jumping distance for each landing strategy. It would appear that increasing height and distance significantly increased VGRF (mean = 18.1%) for all landing strategies. HGRF was more dependent on changes in height for forward landings, while increases in both drop height and/or jump distance were shown to be effective methods of increasing LGRF (mean = 36.2%) for single leg landings. These results can be used to systematically overload jump-landing exercises, which may therefore enhance training prescription to improve performance and decrease injury.