The Acute and Longitudinal Effects of Wearable Resistance: Training to Enhance Change of Direction Performance in Female Netball Athletes

Abstract

It is evident that change of direction (COD) ability is important for many field and court sport athletes, and has even been suggested to be one of the key determinants of successful participation in sport. COD is a complex movement and incorporates key qualities associated with athletic performance such as acceleration, deceleration, and directional changes. One common COD manoeuvre is the 180° turn, which is commonly measured via a 5-0-5 COD test. This test traditionally only provides a total time metric, which is of limited value for strength and conditioning practitioners, when it comes to identifying athlete strengths and weaknesses, and creating individualised programs to enhance athletic performance. In terms of training to enhance COD performance, coaches and practitioners have used a range of different specific and non-specific training methods, such as plyometrics, resistance training, sprint training, and COD specific training. In recent years, the use of wearable resistance (WR) has increased in popularity, due to its potential for providing a sport specific overload. This thesis sought to do the following: 1) unpack COD ability and understand the underlying neuromuscular qualities associated with the phases of COD; 2) develop an advanced diagnostic protocol for measuring COD ability, specifically the 180° turn; and, 3) determine the acute and longitudinal effects of a novel training tool (wearable resistance) on 180° COD performance in female athletes.

In Chapters 2 and 3, the lack of data pertaining to the COD ability of female athletes is highlighted, along with a new perspective on understanding COD and how it can be measured via a novel diagnostic protocol. This novel protocol involved the addition of two extra timing gates to the modified 5-0-5 test, therefore providing proxy split times for acceleration, deceleration, 180° turn, and reacceleration out of the turn. In Chapter 4, ten elite level netball athletes volunteered to be a part of the research to determine the reliability of this protocol. It was found that the proposed novel diagnostic protocol was reliable for measuring COD splits and total time in elite level netball athletes (ICCs = 0.57 – 0.97, CVs = 1.1 – 6.6%). Additionally, the strength of association between the splits and total time was investigated to ensure that splits were measuring independent qualities. The greatest shared variance between sub-phases was 68.9% between deceleration and reacceleration 2 and was the only variable to explain more than 50% of shared variance between sub-phases, suggesting the splits are measuring relatively independent qualities. Further enhancing the diagnostics of this protocol, by including in-sole inertial measurement unit (IMU) technology, was the aim of Chapter 5. The IMU technology was found reliable for providing maximum speed, peak deceleration, and peak acceleration during a modified 5-0-5 COD test (ICCs = 0.57 – 0.96, CVs = 1.8 – 9.5%). Given the acceptable reliability of this advanced diagnostic protocol for a modified 5-0-5 test, it was of interest to determine its utility for coaches with athlete profiling. Chapter 6 focused on determining the insights this novel diagnostic protocol could provide coaches. Of particular interest was to understand what proportion of the test was actually spent in changing direction, if anthropometry and positional differences influenced sub-phase performance and whether a sub-phase analysis could provide better diagnostic information to guide individualisation of programming. It was found that the highest percentage of time was spent during the 180° turn and reacceleration phase (~23%). It appeared that heavier athletes were significantly slower during the modified 5-0-5 test (8.68%), however no differences were identified between taller and shorter players. The use of a sub-phase rank order table provided deeper insights into an individual’s COD sub-phase ability, allowing coaches to easily identify individual athletes’ strengths and weaknesses in a team sport environment.

A repeated measures design was used in Chapter 7, to determine the acute effects of upper and lower body WR on sub-phase and total time 5-0-5 COD performance. Total time was significantly slower for both WR conditions compared to no load (p < 0.05, ES = 0.22 – 0.25). The greatest overload was found for the initial acceleration split (split 1) for both loading conditions (p < 0.05, ES = 0.67 – 0.79). Both loading conditions had moderate to large significant effects on peak deceleration (ES = 0.56 – 0.82) and maximum speed (ES = -0.50 - -0.60). It appeared that both upper and lower body WR significantly overloaded an athlete during a modified 5-0-5 test, and therefore may provide a potential training stimulus to elicit positive COD performance adaptations if used over an extended period of time.

Chapter 8 used a matched-paired randomised control design to determine the effectiveness of warming up with lower-limb WR on COD, sprinting and jumping in female netball athletes. Thirty female high-school premier netball athletes were matched for COD speed and randomly allocated to either WR training (WRT) or an unloaded group (CON). Both groups performed the same 15-minute warm-up two times per week, for six weeks. The WR group was wearing shank loaded WR, which progressed throughout the 6-week intervention. Pre- and post-training data were collected for 5- and 15-m linear sprint times, modified 5-0-5 COD splits and total time, and single leg broad, lateral and vertical countermovement jumps. The main findings of this Chapter were; 1) both groups significantly decreased their 5 m linear sprint times (WRT = -4.41%, ES = -1.60; CON = -2.60%, ES = -0.71), while only the WRT significantly decreased their 15 m time (-2.14%, ES = -1.55); 2) there were no significant decreases in 5-0-5 total time for either group, however the WRT group significantly decreased their acceleration (-7.40%, ES = -0.60) and COD split (-9.73%, ES = -1.02); and, 3) both groups increased their lateral jump (WRT: 4.60 – 6.62%, ES = 0.67 – 0.96; CON: 5.48 – 6.06%, ES = 0.73 - 0.75), while only the WRT group increased (p < 0.05) their broad jump (3.57 – 4.18%, ES = 0.57 – 0.67).

Chapter 9 provided a summary of all the key findings from each Chapter and their practical applications for coaches and practitioners. The limitations of this thesis were also explored, followed by future research directions in the use of WR as a tool for developing athleticism.