Search

Novak, AR, Bennett, KJM, Pluss, MA, Fransen, J, Watsford, ML, and Dascombe, BJ. Power profiles of competitive and noncompetitive mountain bikers. J Strength Cond Res 33(2): 538-543, 2019-The performance of Olympic distance cross-country mountain bikers (XCO-MTB) is affected by constraints such as erosion of track surfaces and mass start congestion which can affect race results. Standardized laboratory assessments quantify interseasonal and intraseasonal cycling potential through the assessment of multiple physiological capacities. Therefore, this study examined whether the power profile assessment (PPA) could discriminate between competitive XCO-MTB and noncompetitive mountain bikers (NC-MTB). Second, it aimed to report normative power profile data for competitive XCO-MTB cyclists. Twenty-nine male participants were recruited across groups of XCO-MTB (n = 14) and NC-MTB (n = 15) mountain bikers. Each cyclist completed a PPA that consisted of increasing duration maximal efforts (6, 15, 30, 60, 240, and 600 seconds) that were interspersed by longer rest periods (174, 225, 330, 480, and 600 seconds) between efforts. Normative power outputs were established for XCO-MTB cyclists ranging between 13.8 ± 1.5 W·kg (5-second effort) and 4.1 ± 0.6 W·kg (600-second effort). No differences in absolute peak power or cadence were identified between groups across any effort length (p > 0.05). However, the XCO-MTB cyclists produced greater mean power outputs relative to body mass than the NC-MTB during the 60-second (6.9 ± 0.8 vs 6.4 ± 0.6 W·kg; p = 0.002), 240-second (4.7 ± 0.7 vs. 3.8 ± 0.4 W·kg; p < 0.001), and 600-second (4.1 ± 0.6 vs. 3.4 ± 0.3 W·kg; p < 0.001) efforts. The PPA is a useful discriminative assessment tool for XCO-MTB and highlights the importance of aerobic power for XCO-MTB performance.

© 2016 National Strength and Conditioning Association. Johnston, RJ, Watsford, ML, Austin, D, Pine, MJ, and Spurrs, RW. Movement profiles, match events, and performance in Australian football. J Strength Cond Res 30(8): 2129-2137, 2016 - This study examined the relationship between movement demands, match events, and match performance in professional Australian football. Data were collected from 19 players using global positioning system units during 2 Australian Football League seasons. A range of movement demands and instantaneous power measures were collected. The players were divided into high-caliber (HC, ≥17/20) and low-caliber (LC, ≤8/20) groups based on the rating score by their coaches. A Mann-Whitney U-test, independent samples t-test, and effect sizes were used to determine whether any differences existed between the 2 groups. The HC group had a significantly higher match duration (7.2%), higher total distance (9.6%), and covered more distance and spent more time high-speed running per minute (12.7 and 11.9%). Although not significant, the effect sizes revealed that the HC group tended to have a higher mean metabolic power output (2.6%) and spent more time at the high power zone (7.9%). For the match event data, the HC group had significantly more involvements with the football. The results demonstrated the higher physical demands placed on the HC group. The findings suggest that analyzing instantaneous power measures can provide valuable information about the physical demands placed on team sport athletes to coaches and conditioning staff.

© 2015 National Strength and Conditioning Association. This study aimed to determine whether a relationship existed between movement demands, match events, and perceptual match load, as determined by rating of perceived exertion (RPE) in professional Australian footballers. The movement variables were collected between 1 and 22 times using global positioning system units from 21 players during the 2011 and 2012 Australian Football League seasons. A range of movement demands and match events were collected to obtain a complete insight into the physical demands and work rates of these athletes. These data were separated into the high-load (HL, ≥9) and low-load (LL, ≤8) RPE groups. A Mann-Whitney U-test, independent samples t-test, and effect sizes were used to determine whether any differences existed between the 2 groups and the size of the difference. The results revealed that the HL groups covered more distance, spent more time, and produced more efforts at the high deceleration zone (2.4-6.7%). Further, the HL group had more possessions and disposals of the football than the LL group (9.2-29.6%). The findings have highlighted the importance of monitoring accelerations, decelerations, and instantaneous power outputs to obtain a comprehensive insight into the physical demands placed on team sport athletes. Furthermore, the results demonstrate that training sessions should involve a focus on drills that are composed of both skill development and physical stimulus element.

The purpose of this research was to investigate the validity and the reliability of 5-Hz MinimaxX global positioning system (GPS) units measuring athlete movement demands. A team sport simulation circuit (files collected from each unit = 12) and flying 50-m sprints (files collected from each unit = 34) were undertaken, during which the total distance covered; peak speed; player load; the distance covered; time spent and number of efforts performed walking, jogging, running, highspeed running, and sprinting were examined. Movement demands were also separately categorized into low-intensity activity, high-intensity running, and very high-intensity running. The results revealed that GPS was a valid and reliable measure of total distance covered (p > 0.05, percentage typical error of measurement [%TEM] < 5%) and peak speed (p > 0.05, %TEM 5-10%). Further, GPS was found to be a reliable measure of player load (%TEM 4.9%) and the distance covered, time spent, and number of efforts performed at certain velocity zones (%TEM 10%). The level of GPS error was found to increase along with the velocity of exercise. The findings demonstrated that GPS is capable of measuring movement demands performed at velocities 20 km·h -1. © 2012 National Strength and Conditioning Association.

© 2015 National Strength and Conditioning Association. This study examined the differences in movement demands and metabolic power output of elite and subelite Australian football (AF) players and quantified the movement profiles of a subelite AF competition. Movement variables were collected from AF players using Global Positioning System devices over 2 AF League (elite) and North East Australian Football League (NEAFL, subelite) seasons. A total of 500 files were collected from 37 elite and subelite nomadic AF players. NEAFL players covered 13,547 m at an average speed of 124.5 m·min -1. Elite players performed more high-speed running (5.7-6.3%) and high acceleration and deceleration efforts (1.9-14.7%, p ≤ 0.05). The elite players had a higher mean metabolic power output (3.2%) and time spent at the very high power zone (15.9%, p ≤ 0.05). In contrast, elite players recorded a lower total match duration than the subelite players (4%, p ≤ 0.05). The contrasting amount of high-intensity activities performed by the 2 groups demonstrates the need to alter the training programs of subelite players to ensure they are capable of meeting the demands of elite football. The differences in match duration suggest that reducing subelite players' match time through increasing their rotations would assist the replication of movement profiles of elite players.

The purpose of this study was to assess the validity and interunit reliability of 10 Hz (Catapult) and 15 Hz (GPSports) Global Positioning System (GPS) units and investigate the differences between these units as measures of team sport athlete movement demands. A team sport simulation circuit was completed by 8 trained male participants. The movement demands examined included: total distance covered (TD), average peak speed, and the distance covered, time spent, and the number of efforts performed low-speed running (0.00-13.99 km·h-1), high-speed running (14.00-19.99 km·h-1), and very highspeed running (>20.00 km·h-1). The degree of difference between the 10 Hz and the 15 Hz GPS units and validity was assessed using a paired samples t-test. Pearson's correlations were also used for validity assessment. Interunit reliability was established using percentage typical error of measurement (%TEM) and intraclass correlations. The findings revealed that 10 Hz GPS units were a valid (p > 0.05) and reliable (%TEM = 1.3%) measure of TD. In contrast, the 15 Hz GPS units exhibited lower validity for TD and average peak speed. Further, as the speed of movement increased the level of error for the 10 Hz and 15 Hz GPS units increased (% TEM = 0.8-19.9). The findings from this study suggest that comparisons should not be undertaken between 10 Hz and 15 Hz GPS units. In general, the 10 Hz GPS units measured movement demands with greater validity and interunit reliability than the 15 Hz units, however, both 10 Hz and 15 Hz units provided the improved measures of movement demands in comparison to 1 Hz and 5 Hz GPS units. © 2014 National Strength and Conditioning Association.

Futsal is the Fèdèration de Internationale Football Association's officially recognized fivea-side indoor soccer, which although increasing in popularity worldwide, lacks the Australian or other English language research necessary to enable the growth of the sport. The purpose of this study was to establish a comprehensive overview of the demands of futsal by a time-motion analysis on 8 Australian National Team players and 10 State League Team players over 4 futsal matches. The study analyzed 6 locomotor activity categories, focusing on total distance covered, total duration of activities, total frequency of activities, effort distance, and effort duration. The national team covered a 42% greater overall distance than the state league team. In terms of relative data normalized for match duration, only the standing duration value was significantly different between the teams. Furthermore, futsal players of elite and subelite level in Australia perform a change in activity every 8-9 seconds on the court, and the national team athletes attained a higher, yet nonsignificant, average match-play velocity. This may be because of the national futsal athletes participating in an extended game duration, potentially suggesting that higher levels of competition facilitate a higher intensity of match play and greater physiological demands on individual players. Apart from the differences in timing structure and overall metabolic work, there was no real difference between the levels of competition within the Australian futsal analysis, although at higher levels of competition, there may be a need for more recovery because of the elevated intensity of the match. When comparing the data with other countries, however, Australian futsal players produce less distance and duration than Spanish futsal players. © 2011 National Strength and Conditioning Association.

Anecdotal reports suggesting that creatine (Cr) supplementation may cause side effects, such as an increased incidence of muscle strains or tears, require scientific examination. In this study, it was hypothesized that the rapid fluid retention and "dry matter growth" evident after Cr supplementation may cause an increase in musculotendinous stiffness. Intuitively, an increase in musculotendinous stiffness would increase the chance of injury during exercise. Twenty men were randomly allocated to a control or an experimental group and were examined for musculotendinous stiffness of the triceps surae and for numerous performance indices before and after Cr ingestion. The Cr group achieved a significant increase in body mass (79.7 +/- 10.8 kg vs. 80.9 +/- 10.7 kg), counter movement jump height (40.2 +/- 4.8 cm vs. 42.7 +/- 5.9 cm), and 20-cm drop jump height (32.3 +/- 3.3 cm vs. 35.1 +/- 4.8 cm) after supplementation. No increase was found for musculotendinous stiffness at any assessment load. There were no significant changes in any variables within the control group. These findings have both performance- and injury-related implications. Primarily, anecdotal evidence suggesting that Cr supplementation causes muscular strain injuries is not supported by this study. In addition, the increase in jump performance is indicative of performance enhancement in activities requiring maximal power output.