Mark Moresi

The assessment of adolescent female athletes using standing and reactive long jumps

The aim of this study was to evaluate the reliability of two long jump tasks and their ability to predict 10 m sprint performance in elite adolescent female athletes. Eight junior national-level female track and field athletes completed three standing (SLJ) and reactive long jumps (RLJ) on portable force plates, followed by three 10 m sprints. Intra-class correlation coefficients (ICC) and coefficients of variation (CV) were calculated to examine reliability. Linear regression results identified the best predictor of average and best 10 m sprint time from the jump kinematic and kinetic measures. The ICCs and CVs indicated good reliability for the majority of kinetic measures however, better reliability was reported for the SLJ. The SLJ was a good predictor of best and average 10 m sprint time, with average horizontal power the best predictor of performance (best; R 2 = 0.751, p = 0.003, Standard Error of Estimate (SEE)% = 2.2 average; R 2 = 0.708, p = 0.005, SEE% = 2.5).

The impact of data reduction on the intra-trial reliability of a typical measure of lower limb musculoskeletal stiffness

Abstract Double-leg repeated jumping tasks are commonly used as measures of lower limb stiffness in exercise science research. Within similar stiffness calculations, variation in data-reduction criteria exists. The impact of these varied data-reduction methods on stiffness measures is unknown. Sixteen adolescent female participants from varied physical activity backgrounds performed 15 self-paced, bent-knee continuous jumps (CJb) on two force plates. Leg stiffness was calculated as the ratio of the peak force and the centre of mass displacement for each contact. Using combinations of criteria based on previous literature, 83 data-reduction methods were applied to the raw data. Data reduction suitability was assessed based on intra-trial reliability, the number of participants excluded and the average contacts excluded. Four data-reduction methods were deemed suitable for use with adolescent female populations, with three consecutive contacts within 1 SD of the average jump frequency considered optimal. The average individual stiffness values were not greatly influenced by the data-reduction method; however, for a single participant, a stiffness change of up to 6 kN · m−1 (30%) was observed. The role and potential impact of data-reduction methods used to evaluate measures of lower limb stiffness during repeated jumping tasks warrants consideration.

What is the Effect of Compression Garments on a Novel Kick Accuracy Task

The purpose of this study was to investigate the effect of wearing long leg compression garments (CGs) on the accuracy of elite football players performing a novel kicking task. A double-blinded, crossover, randomised and controlled laboratory trial was used to examine the contribution of the long leg CGs to kicking accuracy of a drop-punt-kick. The drop-punt-kick is a backward spinning kick often used in Australian Rules. Participants performed 10 drop-punt-kicks towards a target for each garment condition (fitted, over-sized and training shorts) with both their dominant and non-dominant leg. Kicking accuracy data was collected using a high-speed camera. Kicking accuracy between garment conditions was only significantly different when kicking with the dominant leg (p = 0.002). Kicking accuracy was reduced in the fitted CG condition compared to the oversized CG (mean difference = 20 cm, p = 0.018) and for fitted CGs compared to training shorts (mean difference = 21 cm, p = 0.003) indicating that the fitted CGs had a negative effect on kicking accuracy. As these compression garments are worn regularly during training, further research is required to determine the long-term effect on skill development.

Impaired heel to toe progression during gait is related to reduced ankle range of motion in people with Multiple Sclerosis

Background: Gait impairment in people with Multiple Sclerosis results from neurological impairment, muscle weakness and reduced range of motion. Restrictions in passive ankle range of motion can result in abnormal heel‐to‐toe progression (weight transfer) and inefficient gait patterns in people with Multiple Sclerosis. The purpose of this study was to determine the associations between gait impairment, heel‐to‐toe progression and ankle range of motion in people with Multiple Sclerosis. Methods: Twelve participants with Multiple Sclerosis and twelve healthy age‐matched participants were assessed. Spatiotemporal parameters of gait and individual footprint data were used to investigate group differences. A pressure sensitive walkway was used to divide each footprint into three phases (contact, mid‐stance, propulsive) and calculate the heel‐to‐toe progression during the stance phase of gait. Findings: Compared to healthy controls, people with Multiple Sclerosis spent relatively less time in contact phase (7.8% vs 25.1%) and more time in the mid stance phase of gait (57.3% vs 33.7%). Inter‐limb differences were observed in people with Multiple Sclerosis between the affected and non‐affected sides for contact (7.8% vs 15.3%) and mid stance (57.3% and 47.1%) phases. Differences in heel‐to‐toe progression remained significant after adjusting for walking speed and were correlated with walking distance and ankle range of motion. Interpretation: Impaired heel‐to‐toe progression was related to poor ankle range of motion in people with Multiple Sclerosis. Heel‐to‐toe progression provided a sensitive measure for assessing gait impairments that were not detectable using standard spatiotemporal gait parameters. HIGHLIGHTSHeel‐to‐toe progression was measured in people with and without Multiple Sclerosis.In people with Multiple Sclerosis, heel‐to‐toe progression was severely compromised.Impaired heel‐to‐toe progression was related to poor ankle range of motion.The new test revealed functionally and clinically important inter‐limb differences.Heel‐to‐toe progression is a sensitive measure to detect gait abnormalities.

Lower Body Stiffness Modulation Strategies in Well Trained Female Athletes.

Abstract Millett, EL, Moresi, MP, Watsford, ML, Taylor, PG, and Greene, DA. Lower body stiffness modulation strategies in well trained female athletes. J Strength Cond Res 30(10): 2845–2856, 2016—Lower extremity stiffness quantifies the relationship between the amount of leg compression and the external load to which the limb are subjected. This study aimed to assess differences in leg and joint stiffness and the subsequent kinematic and kinetic control mechanisms between athletes from various training backgrounds. Forty-seven female participants (20 nationally identified netballers, 13 high level endurance athletes and 14 age and gender matched controls) completed a maximal unilateral countermovement jump, drop jump and horizontal jump to assess stiffness. Leg stiffness, joint stiffness and associated mechanical parameters were assessed with a 10 camera motion analysis system and force plate. No significant differences were evident for leg stiffness measures between athletic groups for any of the tasks (p = 0.321–0.849). However, differences in joint stiffness and its contribution to leg stiffness, jump performance outcome measures and stiffness control mechanisms were evident between all groups. Practitioners should consider the appropriateness of the task utilised in leg stiffness screening. Inclusion of mechanistic and/or more sports specific tasks may be more appropriate for athletic groups.