Methods of assessing, monitoring and improving strength and ballistic performance in highly trained rugby union players
McMaster, Daniel Travis Williams
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Strength and ballistic qualities are vital to excelling in contact team sports, such as rugby. The assessment, development, retention and decay of these qualities are of great interest, as this information can be utilised by strength and conditioning coaches to better inform and guide the yearly training plan. The overall aim of this project was to develop innovative and effective strength and ballistic assessment batteries that provide an in depth athlete profile through novel analytical approaches to improve current methods of assessment, monitoring and programming in the semi-professional rugby union. In study one, measurement system validation (Chapter 4) outcomes revealed an inconsistency between peak force (PF), peak velocity (PV) and peak power (PP) between the force plate and accelerometers (hip and bar attachments) during vertical jumps (VJ). Both accelerometer attachments were reliable for assessing PF (ICC = 0.80 – 0.83), but were low to moderately reliable for monitoring PV and PP (ICC = 0.35 – 0.77); therefore, subsequent studies in this PhD utilised force plate technology and linear position transducers as the primary means of assessing ballistic performance. In Chapter five, bench throw (BTH) and VJ incremental relative load (body mass-VJ, 15, 30, 45, 60 and 75% 1RM) profiles were also validated using a linear position transducer. The BTH (ICC > 0.80; CV < 11 %) and VJ (ICC > 0.75; CV < 11%) protocols described were relatively stable and reliable within and across testing sessions; and in turn deemed appropriate to monitor BTH and VJ PP, PF and PV adaptations in subsequent studies. The force-velocity profiling data was further analysed to predict maximum BTH and VJ force (Fmax) and velocity (Vmax) to provide a more holistic representation of these ballistic movements. In chapters six and seven, the effects of strength and sprint ability on the previously validated BTH and VJ force-velocity-power profiles were assessed. The comparative statistical analysis illustrated that stronger players produced higher BTH Pmax (14%) and Fmax (17%) and higher VJ Fmax (10%); whereas faster players produced greater VJ Pmax (14%) and Vmax (11%). These findings could be useful to better inform programming of individual and group mechanical efficiencies and deficiencies. The next three chapters used the major findings of these validation and comparative studies to assess the effects of training, detraining and a competitive season on the performance profile. Firstly, the five week complex training (Chapter 8) interventions (strength + heavy ballistic [SHB]; strength + light ballistic [SLB]) herein elicited positive adaptations in 1RM bench press (4 – 9 %) and 1RM squat (9 – 12 %); as well as reductions in 10, 20 and 30 m sprint times (-1 to -2%). SHB training caused positive shifts in Fmax (6 to 10%) and Pmax (12 to 46%); whereas the SLB training caused increases in Vmax (15 to 68%) and Pmax (15 to 36%). Findings indicate that acute SHB and SLB training can be implemented to elicit positive adaptations in strength, sprint ability and ballistic Fmax and Vmax capabilities, respectively. Secondly, the examination of six weeks of resistance detraining (Chapter 9) lead to small reductions in 1RM bench press (-1%) 1RM squat (-6%) and heavy load PF (2%); moderate and very large negative shifts in VJ Vmax (-35%) and Pmax (-14%); and large increases in sprint times over 10, 20 and 30 m (1-3%) were observed. The results suggest that decay rates using high velocity loads are greater than the high force loads. Finally, the effects of a competitive season (Chapter 10) on VJ (PP, F@PP and V@PP) was monitored pre- (58 ± 2 hrs) and post- (41 ± 10 hrs) match to assess weekly ballistic recovery patterns. Decreases in post-match PP (-2%) in comparison to baseline, and increases in pre-match PP (4%) and V@PP (3%) in comparison to post-match were observed. Furthermore, a very large correlation was also observed between PP (r = 0.72) and the number of hours post-match jump testing took place, a trendline fitted to this data also suggests that PP may be reduced for up to 110 hrs. There were also increases in PP (2%) and V@PP (6%) from the first two weeks of competition to the last two weeks,suggesting the mixed method strength and ballistic training performed 2 to 3 times per week throughout the competition period may be sufficient to maintain VJ PP. This information has provided a greater understanding of current in-season ballistic recovery patterns of rugby union competition; and in turn may allow for more informed planning (e.g. recovery modalities and weekly training load management) throughout future competitive seasons.