Daniel Travis McMaster

The reliability of jump kinematics and kinetics in children of different maturity status.

Abstract Meylan, CMP, Cronin, JB, Oliver, JL, Hughes, MG, McMaster, DT. The reliability of jump kinematics and kinetics in children of different maturity status. J Strength Cond Res 26(4): 1015–1026, 2012—The purpose of this study was to determine the reliability of eccentric (ECC) and concentric (CON) kinematic and kinetic variables thought to be critical to jump performance during bilateral vertical countermovement jump (VCMJ) and horizontal countermovement jump (HCMJ) across children of different maturity status. Forty-two athletic male and female participants between 9 and 16 years of age were divided into 3 maturity groups according to peak height velocity (PHV) offset (Post-PHV, At-PHV, and Pre-PHV) and percent of predicted adult stature. All the participants performed 3 VCMJ and HCMJ trials and the kinematics, and kinetics of these jumps were measured via a force plate over 3 testing sessions. In both jumps, vertical CON mean and peak power and jump height or distance were the most reliable measures across all groups (change in the mean [CM] = −5.4 to 6.2%; coefficient of variation [CV] = 2.1–9.4%; Intraclass correlation coefficient [ICC] = 0.82–0.98), whereas vertical ECC mean power was the only ECC variable with acceptable reliability for both jumps (CM = −0.7 to 10.1%; CV = 5.2–15.6%; ICC = 0.74–0.97). A less mature state was “likely” to “very likely” to reduce the reliability of the HCMJ ECC kinetics and kinematics. These findings suggested that movement variability is associated with the ECC phase of CMJs, especially in Pre-PHV during the HCMJ. Vertical CON mean and peak power and ECC mean power were deemed reliable and appropriate to be used in children as indicators of jump and stretch-shortening cycle performance.

The countermovement jump to monitor neuromuscular status: A meta-analysis

OBJECTIVES The primary objective of this meta-analysis was to compare countermovement jump (CMJ) performance in studies that reported the highest value as opposed to average value for the purposes of monitoring neuromuscular status (i.e., fatigue and supercompensation). The secondary aim was to determine the sensitivity of the dependent variables. DESIGN Systematic review with meta-analysis. METHODS The meta-analysis was conducted on the highest or average of a number of CMJ variables. Multiple literature searches were undertaken in Pubmed, Scopus, and Web of Science to identify articles utilizing CMJ to monitor training status. Effect sizes (ES) with 95% confidence interval (95% CI) were calculated using the mean and standard deviation of the pre- and post-testing data. The coefficient of variation (CV) with 95% CI was also calculated to assess the level of instability of each variable. Heterogeneity was assessed using a random-effects model. RESULTS 151 articles were included providing a total of 531 ESs for the meta-analyses; 85.4% of articles used highest CMJ height, 13.2% used average and 1.3% used both when reporting changes in CMJ performance. Based on the meta-analysis, average CMJ height was more sensitive than highest CMJ height in detecting CMJ fatigue and supercompensation. Furthermore, other CMJ variables such as peak power, mean power, peak velocity, peak force, mean impulse, and power were sensitive in tracking the supercompensation effects of training. CONCLUSIONS The average CMJ height was more sensitive than highest CMJ height in monitoring neuromuscular status; however, further investigation is needed to determine the sensitivity of other CMJ performance variables.

Effects of a six-week hip thrust versus front squat resistance training program on performance in adolescent males: A randomized-controlled trial

Abstract Contreras, B, Vigotsky, AD, Schoenfeld, BJ, Beardsley, C, McMaster, DT, Reyneke, JHT, and Cronin, JB. Effects of a six-week hip thrust vs. front squat resistance training program on performance in adolescent males: A randomized controlled trial. J Strength Cond Res 31(4): 999–1008, 2017—The barbell hip thrust may be an effective exercise for increasing horizontal force production and may thereby enhance performance in athletic movements requiring a horizontal force vector, such as horizontal jumping and sprint running. The ergogenic ability of the squat is well known. The purpose of this study was to compare the effects of 6-week front squat and hip thrust programs in adolescent male athletes. Vertical jump height, horizontal jump distance, 10- and 20-m sprint times, and isometric midthigh pull peak force were among the measured performance variables, in addition to front squat and hip thrust 3 repetition maximum (3RM) strength. Magnitude-based effect sizes revealed potentially beneficial effects for the front squat in both front squat 3RM strength and vertical jump height when compared with the hip thrust. No clear benefit for one intervention was observed for horizontal jump performance. Potentially beneficial effects were observed for the hip thrust compared with the front squat in 10- and 20-m sprint times. The hip thrust was likely superior for improving normalized isometric midthigh pull strength and very likely superior for improving hip thrust 3RM and isometric midthigh pull strength. These results support the force vector theory.

Is wireless accelerometry a viable measurement system for assessing vertical jump performance

The aim of this study was to assess the mechanical differences calculated from hip acceleration (accelerometer attached to the hip), bar acceleration (accelerometer attached to barbell) and centre-of-mass acceleration (force plate) during vertical countermovement jumps (CMJs) and the reliability of each system. Eighteen elite male rugby players served as participants. In relation to the force plate, the bar accelerometer revealed similar peak velocity (PV [2%]) and peak power (PP [2%]), but predicted greater peak force (PF [24%]) during the concentric phase, whereas the hip accelerometer predicted similar PF (2%) but underpredicted PV (21%) and PP (24%) during the concentric phase. Both accelerometer attachments were deemed reliable for assessing PF (correlation coefficient, ICC = 0.80–0.83 and standard error of measurement, SEM = 3–13%), but were low/moderately reliable for monitoring PV and PP (ICC = 0.35–0.77 and SEM = 11–23%). The eccentric phase variables were unreliable across all devices and attachment sites. The kinematics and kinetics measured by the three systems (hip accelerometer, bar accelerometer and force plate) varied significantly (p < 0.05). Based on the outcomes, it is recommended that the force plate be used as the primary means of assessing CMJ performance until the stability of wireless accelerometry set-ups and protocols are improved.

A brief review of handgrip strength and sport performance

Abstract Cronin, J, Lawton, T, Harris, N, Kilding, A, and McMaster, DT. A brief review of handgrip strength and sport performance. J Strength Cond Res 31(11): 3187–3217, 2017—Tests of handgrip strength (HGS) and handgrip force (HGF) are commonly used across a number of sporting populations. Measures of HGS and HGF have also been used by practitioners and researchers to evaluate links with sports performance. This article first evaluates the validity and reliability of various handgrip dynamometers (HGD) and HGF sensors, providing recommendations for procedures to ensure that precise and reliable data are collected as part of an athletes testing battery. Second, the differences in HGS between elite and subelite athletes and the relationships between HGS, HGF, and sports performance are discussed.

Force-Velocity-Power Assessment in Semiprofessional Rugby Union Players.

Abstract McMaster, DT, Gill, N, Cronin, J, and McGuigan, M. Force-velocity-power assessment in semiprofessional rugby union players. J Strength Cond Res 30(4): 1118–1126, 2016—There is a constant and necessary evolution of training and assessment methods in the elite contact sports; as is required to continually improve the physical qualities of these respective athletes to match the growing sport and position-specific performance demands. Our aim was to examine the differences between ballistic upper body performance profiles and maximum upper body strength of elite rugby union forwards and backs. Twenty semiprofessional male rugby union players (age = 21.1 ± 3.0 years; mass = 94.9 ± 9.7 kg) were assessed for maximum bench press strength (1RM bench press = 121.3 ± 21.8 kg) and maximum throw power (Pmax), force (Fmax), and velocity (V[Combining Dot Above]max) from an incremental relative load testing protocol (15, 30, 45, 60, and 75% 1RM). Player rankings were also included to identify individual strength and weaknesses. The forwards were moderately stronger (effect size [ES] = 0.96; p = 0.01), produced significantly greater Fmax (ES = 1.17–1.41; p = 0.01) and were more powerful (ES = 0.57–0.64; p < 0.43) than the backs. V[Combining Dot Above]max differences were trivial to small (ES = −0.32 to −0.65; p > 0.15). There were inherent differences in strength and Fmax between the forwards and backs most likely because of the physical demands of these respective positions. Improvements in upper body strength may in turn improve ballistic force and power production, but not necessarily velocity capabilities. From the Fmax and V[Combining Dot Above]max observations, the forwards seem to be more force dominant and the backs more velocity dominant. Pmax, Fmax, and V[Combining Dot Above]max may be used to highlight proficient and deficient areas in ballistic upper body performance; the individual rankings could be further used to identify and possibly rectify individual deficiencies.

Strength and Conditioning for Throwing in Cricket

ABSTRACT IN CRICKET, THE ABILITY TO THROW A BALL AT HIGH VELOCITY WITH GREAT ACCURACY IS CRITICAL TO SUCCESSFUL PERFORMANCE AND OFTEN DETERMINES THE OUTCOME OF MATCHES. THE SKILL OF CRICKET FIELDING INCORPORATES A MOVEMENT PHASE AND A PICK-UP AND THROW PHASE AIMED AT DECREASING RUN RATE OR PRODUCING A RUN OUT OF THE OPPOSITION. A MAJOR ISSUE IN CRICKET IS THE RISK OF INJURY TO PLAYERS ATTRIBUTED TO AN ACUTE SPIKE IN THROWING INTENSITY AND VOLUME DURING PRACTICE AND MATCHES. THIS ARTICLE DISCUSSES STRENGTH AND CONDITIONING PRACTICES THAT MAY REDUCE THE PREVALENCE OF THROWING-RELATED INJURIES AND IMPROVE THROWING PERFORMANCE.

Assessing change of direction ability in badminton athletes

ABSTRACT THIS REVIEW PROVIDES A STOCK TAKE OF BADMINTON-SPECIFIC CHANGE OF DIRECTION (COD) RESEARCH AND PROVIDES RECOMMENDATIONS TO PRACTITIONERS FOR COD ASSESSMENT. THE REVIEW WILL EXAMINE RELATIONSHIPS BETWEEN COD AND THE FOLLOWING MEASURES: ANTHROPOMETRY, ELASTIC STRENGTH, CONCENTRIC STRENGTH, LEG MUSCLE IMBALANCES, TECHNIQUE, STRAIGHT-LINE SPRINT SPEED, AND FLEXIBILITY. A BADMINTON-SPECIFIC COD ASSESSMENT BATTERY IS PROPOSED WITH THE INCLUSION OF 2 NEW TESTS: A MULTIDIRECTIONAL LUNGE TEST AND A MULTIDIRECTIONAL CYCLIC COD TEST.