The Role of General Motor Ability and Agility in Sport Performance

The concept and assessment of general motor ability (GMA) has declined in favour of specialisation and training specificity in athlete development (AD). Early specialisation and a focus on specificity have increased the physical and psychological loading on athletes entering formal development structures or programmes. As a consequence, the use of generic movement training and the use of GMA has significantly decreased. It is suggested that this may be creating athletes who are less adaptable and resilient, with regards to learning new motor skills, transferring skills, and potentially being more prone to injury. Accordingly, the role of general motor ability in sports performance remains unclear, and there is a lack of research which examines its' potential in facilitating improvement in performance. Alongside the diminished role of GMA, there is obfuscation on the role agility plays in AD. The concept of agility is currently constrained by an overly simplistic interpretation that limits it to reactive directional changes. Developing a novel construct of agility, where it can offer both generic and specific qualities, may support the operationalisation of GMA in contemporary AD programmes. In doing so, this may also help to balance the impact of early specialisation and training specificity. Founded on this rationale the objectives of this thesis were as follows: 1. To provide an overview of GMA and agility, including a reinterpretation of the agility construct. 2. To establish the importance of GMA in AD by examining the association between GMA, physical attributes and technical playing attributes in youth RL players. 3. To explore the mechanisms which may underpin GMA. 4. To investigate the development of GMA and explore the nature of longitudinal changes in GMA between youth RL players and youth school children. 5. To explore the role of GMA in acute skill transfer and describe its role in facilitating athlete resilience and adaptability in motor skill learning. Addressing the first objective Chapter Two provides a critical overview of GMA and agility in sports performance and AD; specifically reviewing the conceptualisation of GMA and presenting a reinterpretation of the agility construct. The second and third objectives were met using the context of Rugby League (RL). The correlational study in Chapter Three used 33 junior RL players to establish the importance of GMA, concerning the positive relationship with physical and technical playing attributes. In Chapter Four, correlational and predictive analysis on tests of GMA, generic and specific agility on 107 junior RL players were used to explore the mechanisms which may underpin GMA. Importantly, GMA had excellent predictive abilities on the performance of generic and specific agility movements. The results of an analysis of specific kinematic variables of preplanned and reactive change of direction (CoD) tasks suggested movement variability was important in these CoD tasks. Objective four was achieved by employing a quasi-experimental design, 36 youths drawn from two groups were pre and post tested on measures of GMA, generic and specific agility to assess the impact of a generic agility intervention and a physical education (PE) curriculum. GMA is not static; training status and varied practice influence its level. In addressing the final objective, Chapter Six used multilevel modelling to examine the clustering of data on six repeated trials on a novel task in high and low GMA groups. Thirty eight students were assessed for GMA and the evolution of their novel task performance. Better GMA performers were able to outperform participants with low GMA on the novel task; findings being indicative of better skill transfer. In conclusion, the five studies aimed to provide a significant contribution to the scientific knowledge. GMA, operationalised through generic agility, does relate to sport-specific performance. Better GMA relates to enhanced performance on a complex and novel CoD task. While GMA is in a state of flux and can be improved by various types of physical activity (PA). Further research into the specific nature of generic agility training, for performance and health, to help sustain motor competence and reduce injury is recommended

Effects of In-Season Velocity- Versus Percentage-Based Training in Academy Rugby League Players

Purpose: To compare the effects of velocity-based training (VBT) versus percentage-based training (PBT) on strength, speed and jump performance in academy rugby league players during a 7-week in-season mesocycle. Methods: Twenty-seven rugby league players competing in the Super League U19s Championship were randomised to VBT (n = 12) or PBT (n = 15). Both groups completed a 7-week resistance training intervention (2x/week) that involved the back squat. The PBT group used a fixed load based on a percentage of one repetition maximum (1RM), whereas the VBT group used a modifiable load based on individualised velocity thresholds. Biomechanical and perceptual data were collected during each training session. Back squat 1RM, countermovement jump (CMJ), reactive strength index (RSI), sprint times, and back squat velocity at 40-90% 1RM were assessed pre- and post-training. Results: The PBT group showed likely to most likely improvements in 1RM strength and RSI, whereas the VBT group showed likely to very likely improvements in 1RM strength, CMJ height, and back squat velocity at 40 and 60% 1RM. Sessional velocity and power were most likely greater during VBT compared with PBT (standardised mean differences [SMDs] = 1.8 to 2.4), whilst time under tension and perceptual training stress were likely lower (SMDs = 0.49 to 0.66). The improvement in back squat velocity at 60% 1RM was likely greater following VBT compared with PBT (SMD = 0.50). Conclusion: VBT can be implemented during the competitive season, instead of traditional PBT, to improve training stimuli, decrease training stress, and promote velocity-specific adaptations

Test-Retest Reliability of a Commercial Linear Position Transducer (GymAware PowerTool) to Measure Velocity and Power in the Back Squat and Bench Press

This study examined the test-retest reliability of the GymAware PowerTool (GYM) to measure velocity and power in the free-weight back squat and bench press. Twenty-nine academy rugby league players (age: 17.6 ± 1.0 years; body mass: 87.3 ± 20.8 kg) completed 2 test-retest sessions for the back squat followed by 2 test-retest sessions for the bench press. GYM measured mean velocity (MV), peak velocity (PV), mean power (MP), and peak power at 20, 40, 60, 80, and 90% of 1 repetition maximum (1RM). GYM showed good reliability (intraclass correlation coefficient [ICC] and standard error of measurement percentage, respectively) for the measurement of MV at loads of 40 (0.77, 3.9%), 60 (0.83, 4.8%), 80 (0.83, 5.8%), and 90% (0.79, 7.9%) of 1RM in the back squat. In the bench press, good reliability was evident for PV at 40 (0.82, 3.9%), 60 (0.81, 5.1%), and 80% (0.77, 8.4%) of 1RM, and for MV at 80 (0.78, 7.9%) and 90% (0.87, 9.9%) of 1RM. The measurement of MP showed good to excellent levels of reliability across all relative loads (ICC ≥0.75). In conclusion, GYM provides practitioners with reliable kinematic information in the back squat and bench press, at least with loads of 40–90% of 1RM. This suggests that strength and conditioning coaches can use the velocity data to regulate training load according to daily readiness and target specific components of the force-velocity curve. However, caution should be taken when measuring movement velocity at loads <40% of 1RM

Test-Retest reliability of a commercial linear position transducer (GymAware PowerTool) to measure velocity and power in the Back Squat and Bench Press

This study examined the test-retest reliability of the GymAware PowerTool (GYM) to measure velocity and power in the free-weight back squat and bench press. Twenty-nine academy rugby league players (age: 17.6 ± 1.0 years; body mass: 87.3 ± 20.8 kg) completed 2 test-retest sessions for the back squat followed by 2 test-retest sessions for the bench press. GYM measured mean velocity (MV), peak velocity (PV), mean power (MP), and peak power at 20, 40, 60, 80, and 90% of 1 repetition maximum (1RM). GYM showed good reliability (intraclass correlation coefficient [ICC] and standard error of measurement percentage, respectively) for the measurement of MV at loads of 40 (0.77, 3.9%), 60 (0.83, 4.8%), 80 (0.83, 5.8%), and 90% (0.79, 7.9%) of 1RM in the back squat. In the bench press, good reliability was evident for PV at 40 (0.82, 3.9%), 60 (0.81, 5.1%), and 80% (0.77, 8.4%) of 1RM, and for MV at 80 (0.78, 7.9%) and 90% (0.87, 9.9%) of 1RM. The measurement of MP showed good to excellent levels of reliability across all relative loads (ICC ≥0.75). In conclusion, GYM provides practitioners with reliable kinematic information in the back squat and bench press, at least with loads of 40–90% of 1RM. This suggests that strength and conditioning coaches can use the velocity data to regulate training load according to daily readiness and target specific components of the force-velocity curve. However, caution should be taken when measuring movement velocity at load

Validity of various portable devices to measure sit-to-stand velocity and power in older adults

Background: Movement velocity and power in a single STS are related to functional performance in older adults. Identifying accessible tools that provide valid measures of STS velocity/power would allow practitioners to evaluate physical function in clinical settings where time, space and finances are limited. Research question: Does a linear position transducer (LPT), iPhone application (App), and inertial measurement unit (IMU) obtain valid measurements of velocity and power during a single STS compared with 3D motion capture? Methods: Twenty-seven community-dwelling older adults aged ≥60 years completed a single STS test with mean velocity and power simultaneously measured with 3D motion capture, an LPT, IMU and App. Acceptable validity was established if the Pearson correlation coefficient (r) was very high (≥0.7) and bias as a standardised effect size (ES) was small (<0.6). The relationship between STS velocity/power and 30-s chair STS performance was also evaluated. Results: Measures of STS velocity obtained by the LPT (r = 0.94, ES =-0.21) and App (r = 0.89, ES =-0.19) were very highly valid when compared to 3D motion capture, and were very strongly related to 30-s STS performance (r ≥0.74). The LPT (r = 0.87, ES = 0.13) and App (r = 0.74, ES =-0.12) also showed very high correlations and negligible bias for measuring STS power. Data collected by the IMU failed to meet our predetermined threshold of acceptable validity for STS velocity (r = 0.72, ES = 1.00) or power (r = 0.61, ES = 0.34). Significance: The LPT and iPhone App, but not the IMU, are valid tools for measuring STS velocity and power in community-dwelling older adults. Clinicians can use STS velocity obtained by either the LPT or App as a simple and valid proxy for functional status, which could help identify patients at high-risk of incident disability

Validity and reliability of a wearable inertial sensor to measure velocity and power in the back squat and bench press

Orange, ST, Metcalfe, JW, Liefeith, A, Marshall, P, Madden, LA, Fewster, CR, and Vince, RV. Validity and reliability of a wearable inertial sensor to measure velocity and power in the back squat and bench press. J Strength Cond Res 33(9): 2398-2408, 2019-This study examined the validity and reliability of a wearable inertial sensor to measure velocity and power in the free-weight back squat and bench press. Twenty-nine youth rugby league players (18 ± 1 years) completed 2 test-retest sessions for the back squat followed by 2 test-retest sessions for the bench press. Repetitions were performed at 20, 40, 60, 80, and 90% of 1 repetition maximum (1RM) with mean velocity, peak velocity, mean power (MP), and peak power (PP) simultaneously measured using an inertial sensor (PUSH) and a linear position transducer (GymAware PowerTool). The PUSH demonstrated good validity (Pearson's product-moment correlation coefficient [r]) and reliability (intraclass correlation coefficient [ICC]) only for measurements of MP (r = 0.91; ICC = 0.83) and PP (r = 0.90; ICC = 0.80) at 20% of 1RM in the back squat. However, it may be more appropriate for athletes to jump off the ground with this load to optimize power output. Further research should therefore evaluate the usability of inertial sensors in the jump squat exercise. In the bench press, good validity and reliability were evident only for the measurement of MP at 40% of 1RM (r = 0.89; ICC = 0.83). The PUSH was unable to provide a valid and reliable estimate of any other criterion variable in either exercise. Practitioners must be cognizant of the measurement error when using inertial sensor technology to quantify velocity and power during resistance training, particularly with loads other than 20% of 1RM in the back squat and 40% of 1RM in the bench press

Isokinetic strength qualities that differentiate rapid deceleration performance in male youth academy soccer players

Introduction Decelerating (DEC) is just as frequent as accelerating in contemporary soccer match play (Russell et al., 2014). Recent evidence suggests that lower body eccentric strength directly improves the ability of a player to produce and tolerate braking forces (Spiteri et al., 2014). The aim of the present study was to identify if measures of isokinetic strength can differentiate performance of a rapid DEC maneuver. Method Nineteen (n=19) academy youth soccer players (age: 16.7 + 1yrs; height: 175 + 8.4cm ; body mass: 69.1+ 7.5kg; body fat: 9.5 + 3.9%) participated in the study. Tests included: isokinetic dynamometer (Cybex ΙΙ, Cybex International Inc., New York, USA) strength profiling of quadricep (Q) and hamstring (H) peak concentric (con) and eccentric (ecc) torque (both dominant [kicking leg] and non-dominant legs) assessed at slow (60°/s) and fast (180°/s) angular velocities. Functional H:Q ratios representative of knee flexion (Hcon:Qecc) and extension (Hecc:Qcon) was also calculated; 30m linear sprint time (with 5m, 10m and 20m splits) was recorded using a single beam timing system (Witty, Microgate, Italy) and rapid DEC quantified using time to stop (TTS) and distance to stop (DTS) determined following a 20m maximal acceleration (within 5% threshold of best 20m linear sprint time) using video analysis (Dartfish ProSuite 2011, Fribourg, Switzerland) captured from a 50Hz video camera (Panasonic HDC-HS900, Japan). Results 10, 20 and 30m sprint times had significantly large correlations with fast con peak Q torque (dom, r=-0.624, -0.568, - 0.621 and non-dom, r=-0.513, -0.512, -0.509) with fast peak H torque comprising significant correlations in the dom leg (r= -0.773, -0.561, -0.761) with moderate to large correlations in the non-dom leg (r= -0.5, -0.468, -0.464). At slow velocity con peak H torque had moderate to large correlations with 10, 20 and 30m sprint times. No significant correlations were found for peak con strength in either Q or H for DEC performance (TTS and DTS). Slow velocity Ecc peak Q torque (dom, r= -0.503, nondom, r=-0.542) and time to peak torque (r=-0.465) was significantly correlated to DEC TTS. No significant correlations were found for fast ecc strength parameters in Q or H for either sprint or DEC performance. Sprint and DEC performance had no significant correlations. Discussion The present study illustrates the need for specific strength qualities for attainment of high running velocities and rapid DEC performance. Specifically, players with superior sprint speed can produce high peak con forces in both Q and H at fast velocities. DEC seems to be a unique movement skill requiring specific ecc strength qualities. Interestingly, in this study slow velocity ecc strength of the Q seems to be critical for production of braking forces and reducing the time spent DEC. Increased time spent DEC has been found to increase tissue damage and muscle soreness, subsequently affecting post match recovery kinetics (Young et al., 2012). In conclusion this study highlights the need for careful consideration to developing strength qualities needed for DEC alongside those more commonly known for sprinting and accelerating. References Russell, M., Sparkes, W., Northeast, J., Cook, C. J., Love, T. D., Bracken, R. M., & Kilduff, L. P. (2014). Changes in acceleration and deceleration capacity throughout professional soccer match-play. Journal of Strength and Conditioning Research, in press. Spiteri, T., Nimphius, S., Hart, N. H., Specos, C., Sheppard, J. M., & Newton, R. U. (2014). Journal of Strength & Conditioning Research, 28(9), 2415–23. Young, W. B., Hepner, J., & Robbins, D. W. (2012). Journal of Strength and Conditioning Research, 26(2), 492–6

Back to the Future – In support of a renewed emphasis on generic agility training within sports-specific developmental pathways

Perhaps as a consequence of increased specialism in training and support, the focus on engendering and maintaining agility as a generic quality has diminished within many contemporary sports performance programmes. Reflecting this, we outline a rationale suggesting that such a decreased focus represents an oversight which may be detrimental to maximising the potential of performers. We present an evidence-based argument that both generic and specific elements of agility performance should be consistently emphasised within long-term performance-training programmes. We contend that prematurely early specialisation in athlete development models can diminish focus on generic movement skill development with a subsequent detriment in adult performance. Especially when this is coupled with poor primary physical education and limited movement experiences. More speculatively, we propose that generic agility can play a role in operationalising movement development through facilitating skill transfer: thereby enabling the learning of new skills, reduce incidence of injury and facilitating re-learning of old skills during rehabilitation and Return-to-Play processes