Tania Spiteri

Date of Award

2012

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Master of Science

School

School of Exercise and Health Science

Faculty

Faculty of Computing, Health and Science

First Supervisor

Dr Jodie L. Cochrane

Second Supervisor

Dr Sophia Nimphius

Abstract

Study 1: Evaluation of a new lower body reaction time test. The purpose of this study was to investigate the reliability of two lower body reaction time (RT) tests to determine differences in RT between genders and compatible and incompatible conditions. Fifteen male and female (n=30) (22.63 ± 2.88 yrs; 175.31 ± 8.72 cm; 67.33 ± 9.71 kg) sport science students participated in this study. Subjects were required to complete two lower body RT tests responding to an arrow during compatible (same direction) and incompatible (opposite direction) stimulus-response conditions. The “simple” foot RT test, required subjects to step quickly on the appropriate mat, as directed by the stimulus, with response time being measured. The “complex” foot RT test required subjects to leap off a force plate to the appropriate mat in response to the stimulus, with RT, movement time (MT) and total movement time (TMT), being measured. Intra-class coefficient, coefficient of variation, and paired samples t-test (p ≤ 0.05) were calculated for all variables. High reliability was observed for both tests between compatible and incompatible conditions. Significant differences (p ≤ 0.05) were observed between genders for RT during the “simple” RT test. Significant differences (p≤ 0.05) were observed for MT and TMT during compatible and incompatible conditions for the “complex” RT test. In conclusion, both tests are reliable to determine lower body RT during both conditions. MT and TMT during the “complex” RT test were significantly different suggesting MT could be the discriminating factor between conditions as well as genders. Examining lower body RT during a movement commonly observed in sport may provide coaches more detail about athletes cognitive and athletic ability, enabling the components of RT to be trained.

Study 2: Human stimulus reliability during an offensive and defensive agility protocol. Athletes are required to change direction in response to opposition movements during offensive and defensive orientations throughout the duration of a game. Currently, humans have been used as a stimulus during agility protocols performing movements for athletes to respond to. However, the reliability of these movements and athlete running times during offensive and defensive condition has yet to be examined. Therefore, the purpose of this study was to assess the reliability of athlete running times and movements performed by a human stimulus during offensive and defensive agility protocols. One human stimulus was tested across two sessions completing 200 movement patterns, with five athletes performing agility trials responding to the human stimulus during both offensive and defensive conditions. All variables analyzed display high intraday reliability, revealing movements performed by the human stimulus (intraclass correlation coefficient (ICC): 0.71-0.99; coefficient of variation (CV): 1.11-4.77; typical error (TE): 0.15-0.59) and athlete running times (offensive: ICC: 0.91; CV: 3.30; TE: 0.06, defensive: ICC: 0.90; CV: 3.60; TE: 0.05) to be reliable. Further, no significant differences (p ≥ 0.05) were observed for human stimulus movement variables or athlete running times between the two testing sessions, however athletes produced a significantly faster running time (p= 0.009) during the defensive condition. Results suggest the movements performed by a human stimulus can be reliable supporting the implementation of a human stimulus during agility protocols to detect the smallest worthwhile change in athletic performance. Further, the results indicate the importance of measuring athlete’s agility performance during both offensive and defensive conditions as a guide for training programs to improve agility performance.

Study 3: Comparison of running times during a change of direction, offensive and defensive agility protocol. Change of direction (COD) movements are often performed under offensive and defensive situations to evade or pursue opponents. Currently response times, have been quantified during COD and defensive agility conditions, thus there is a need to investigate athlete’s response times during offensive agility conditions. Specific response times; reaction time (RT), movement time (MT) and total movement time (TMT) were identified to determine if a significant difference in response time occur between genders during COD and agility protocols. Twelve male and female (n=24) recreational team sport athletes participated in this study, with each athlete performing 10 COD trials and 12 offensive and 12 defensive agility trials in response to movements of a human stimulus. Comparison of response times reveal male athletes demonstrate a significantly faster (p = 0.001; ES = 1.82) TMT (0.32 s) during the COD protocol, and a significantly faster (p = 0.001; ES = 0.52 – 0.74) RT (0.39 s) and TMT (0.245 s) compared to females during both offensive and defensive agility protocols. Although no significant differences were observed, females produced a faster TMT during the defensive condition, whilst males were faster during the offensive condition. The results of this study indicate both COD and agility protocols are able to detect differences in performance between genders. These findings also highlight the importance to isolate and measure specific movement times during both offensive and defensive conditions to gain further insight to athlete’s agility performance.

Study 4: Comparison of force profiles between genders and strength during pre-planned change of direction movements. The aim of this study was to compare the magnitude of vertical and horizontal force-time and impulse variables between genders and lower body strength during a 45° change of direction (COD) test. Twelve male and female (n=24) recreational team sport athletes participated in this study. Each subject performed 10 pre-planned COD trials (5 left, 5 right) to collect relevant ground reaction force and impulse data. Subjects were further split into stronger and weaker groups based on unilateral isometric strength measurements of dominant and non-dominant limbs. Group (gender; strength level) by leg dominance (2x2) MANOVA’s were conducted to examine differences between groups across all variables, with follow up ANOVA’s conducted to determine where significant differences (p ≤ 0.05) occurred. Significantly faster post-stride velocity and greater vertical braking force, braking impulse and propulsive force was observed for males and the stronger group. Additionally, the stronger group demonstrated a significantly greater vertical propulsive impulse, horizontal braking force and angle of maximum braking force application, further highlighting strength as an important mechanism underpinning COD movements. This preliminary study demonstrates that specific force-time and impulse variables differ between genders and strength indicating training programs should targeted towards improving lower body strength and power to produce a faster COD performance.

Study 5: Ground reaction force application during offensive and defensive agility manoeuvers in male and female athletes. The aim of this study was to compare the magnitude of vertical ground reaction force-time and impulse variables during an offensive and defensive agility protocol between genders. Twelve male and female (n=24) recreational team sport athletes participated in this study, each performing 12 offensive and 12 defensive agility trials (6 left, 6 right) to collect relevant ground reaction force (GRF) and impulse data. Subjects also completed six unilateral isometric back squats to determine peak force for each limb and limb dominance. Group (gender) by condition (2x2) MANOVA’s were conducted to examine differences between groups across all variables, with follow up ANOVA’s conducted to determine where significant differences (p ≤ 0.05) occurred. The results indicate male subjects demonstrate a significantly greater braking force and impulse, lower body strength, and a faster initial reaction to the stimulus, enabling a faster post-stride velocity and reacceleration in the new direction compared to female subjects, during offensive and defensive agility conditions. Further differences between offensive and defensive conditions appear to be attributed to differences in reaction time and processing speed between genders. This preliminary study demonstrates that specific force-time and impulse variables differ between genders during offensive and defensive agility conditions, indicating the importance to assess and train athletes under both conditions to improve overall agility performance.

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