Australian football (AF) is a physical game involving large running volumes, rapid directional changes, and high-velocity running efforts. Minimizing injury risk is a priority for sports medicine/science staff as injuries have a detrimental impact on team and individual success. 1 An increased
Marcus J. Colby, Brian Dawson, Peter Peeling, Jarryd Heasman, Brent Rogalski, Michael K. Drew and Jordan Stares
Nick Ball and Joanna Scurr
Electromyograms used to assess neuromuscular demand during high-velocity tasks require normalization to aid interpretation. This paper posits that, to date, methodological approaches to normalization have been ineffective and have limited the application of electromyography (EMG). There is minimal investigation seeking alternative normalization methods, which must be corrected to improve EMG application in sports. It is recognized that differing normalization methods will prevent cross-study comparisons. Users of EMG should aim to identify normalization methods that provide good reliability and a representative measure of muscle activation. The shortcomings of current normalization methods in high-velocity muscle actions assessment are evident. Advances in assessing alternate normalization methods have been done in cycling and sprinting. It is advised that when normalizing high-intensity muscle actions, isometric methods are used with caution and a dynamic alternative, where the muscle action is similar to that of the task is preferred. It is recognized that optimal normalization methods may be muscle and task dependent.
Matthew C. Varley, George P. Elias and Robert J. Aughey
To compare the peak 5-min period of high-velocity running (HiVR) during a soccer match using a predefined vs a rolling time interval.
Player movement data were collected from 19 elite Australian soccer players over 11 competitive matches (77 individual match files) using a 5-Hz global-positioning system. Raw velocity data were analyzed to determine the period containing the greatest HiVR distance per match half and the distance covered in the subsequent epoch. Intervals were identified using either a predefined (distance covered in 5 min at every 5-min time point) or rolling (distance covered in 5 min from every time point) method. The percentage difference ± 90% confidence limits were used to determine differences between methods.
Predefined periods underestimated peak distance covered by up to 25% and overestimated the subsequent epoch by up to 31% compared with rolling periods. When the distance decrement between the peak and following period was determined, there was up to a 52% greater reduction in running performance using rolling periods than predefined ones.
It is recommended that researchers use rolling as opposed to predefined periods when determining specific match intervals because they provide a more accurate representation of the HiVR distance covered. This will avoid underestimation of both match running distance and the decrement in running performance after an intense period of play. This may have practical implications for not only researchers but also staff involved in a club setting who use this reduction as evidence of transient fatigue during a match.
Tomoyuki Matsuo, Rafael F. Escamilla, Glenn S. Fleisig, Steven W. Barrentine and James R. Andrews
This study investigated differences in kinematic and temporal parameters between two velocity groups of baseball pitchers. Data were collected from 127 healthy college and professional baseball pitchers. Those who threw faster than 1 SD above the sample mean (>38.0 m/s) were assigned to the high velocity group (n = 29), and those who threw slower than 1 SD below the sample mean (<34.2 m/s) were assigned to the low velocity group (n = 23). Twelve kinematic parameters and 9 temporal parameters were measured and analyzed. The pattern of lead knee movement was also investigated. Maximum shoulder external rotation, forward trunk tilt at the instant of ball release, and lead knee extension angular velocity at the instant of ball release were significantly greater in the high velocity group. Maximum lead knee flexion angular velocity was significantly greater in the low velocity group. Seventy percent of the high velocity group showed knee extension during the approach to ball release, whereas the low velocity group showed a variety of knee movement patterns involving less knee extension and more knee flexion. The greater shoulder external rotation in the high velocity group produced an increased range of motion during the acceleration phase.
Hilde Lohne-Seiler, Monica K. Torstveit and Sigmund A. Anderssen
The aim was to determine whether strength training with machines vs. functional strength training at 80% of one-repetition maximum improves muscle strength and power among the elderly. Sixty-three subjects (69.9 ± 4.1 yr) were randomized to a high-power strength group (HPSG), a functional strength group (FSG), or a nonrandomized control group (CG). Data were collected using a force platform and linear encoder. The training dose was 2 times/wk, 3 sets × 8 reps, for 11 wk. There were no differences in effect between HPSG and FSG concerning sit-to-stand power, box-lift power, and bench-press maximum force. Leg-press maximum force improved in HPSG (19.8%) and FSG (19.7%) compared with CG (4.3%; p = .026). Bench-press power improved in HPSG (25.1%) compared with FSG (0.5%, p = .02) and CG (2%, p = .04). Except for bench-press power there were no differences in the effect of the training interventions on functional power and maximal body strength.
Erica S. Albertin, Emilie N. Miley, James May, Russell T. Baker and Don Reordan
of treatments. • The search of the literature provided 5 randomized control trial studies, which met the inclusion criteria and were included. 3 , 5 – 8 • Three studies compared use of the MC on the hip joints to traditional therapy treatments, 3 , 7 , 8 one study compared high-velocity low
Amador García-Ramos, Guy Gregory Haff, Francisco Luis Pestaña-Melero, Alejandro Pérez-Castilla, Francisco Javier Rojas, Carlos Balsalobre-Fernández and Slobodan Jaric
individualized relationships between load (kg) and velocity (m·s −1 ) were established through a linear model applied to the data provided by the high velocity (≈1.0 m·s −1 ) and low velocity (≈0.5 m·s −1 ) separately for MV and MPV (ie, we used the same experimental points that were used for the application of
Mark G.L. Sayers and Stephen Bishop
potential to oversimplify the role that the various power-based strength qualities (eg, maximum force [F max ], rate of force development [RFD max ], etc) 13 – 15 and technique 9 , 10 , 16 have in the development of power in high-velocity sporting movements. Additionally, power-based strength variables
Esther Morencos, Blanca Romero-Moraleda, Carlo Castagna and David Casamichana
groups remained similar throughout each QTR in the distance covered at HSR (m). MID covered 67.1% (13.4%) and FWD covered 59.3% (11.6%) more distance (m and m·min −1 ) in these high-velocity zones than BK ( P = .01; moderate ES). Sprinting distance decreased in BK (8.3% [3.5%]) in relative values ( P
Ana M. F. Barela, José A. Barela, Natália M. Rinaldi and Diana R. de Toledo
This study examined the influence of both optic flow characteristics and intention on postural control responses. Two groups of 10 adults each were exposed to the room’s movement either at 0.6 cm/s (low velocity group) or 1.0 cm/s (high velocity group). All the participants stood in the upright stance inside of a moving room and were informed about the room movement only after the fourth trial as they were asked to resist to its influence. Results revealed that participants from both groups were influenced by the imposed visual stimulus in the first trials, but the coupling strength was weaker for the high velocity group. The request to resist the visual influences decreased visual influences on body sway, but only for the low velocity group. These results indicate that intention might play a role in stimulus influences on body sway but it is stimulus dependent.