Time-motion analysis of international and national level futsal

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

Differences in lower-body stiffness between levels of netball competition

© 2015 National Strength and Conditioning Association. There are many notable differences in physical and skill attributes between competition levels, especially in team sports. Stiffness is an important mechanical factor to measure when considering athletic performance and injury incidence. Active vertical stiffness (K vert) during hopping and passive stiffness during lying and standing were measured during the preseason period for 46 female netballers (24.0 ± 3.7 years, 72.2 ± 7.6 kg, 175.2 ± 6.7 cm). Participants were classified as elite, sub-elite, representative or recreational based on their current level of competition. A 1-way analysis of variance revealed that elite players possessed significantly higher K vert than recreational players (p 0.018). Large effect sizes (ES) suggested that elite players also possessed higher K vert than sub-elite (d 1.11) and representative (d 1.11) players. A number of large and moderate ES were also present when comparing the passive stiffness of elite players to their lower-ranked counterparts. The results of this study suggest that elite players possess higher levels of active stiffness when compared with their lower-ranked counterparts. The differences in stiffness levels may contribute to a player's ability to physically perform at an elite level and also provide one explanation into elevated rates of injury at higher levels of competition

A Comparison of Training With a Velocity Loss Threshold or to Repetition Failure on Upper-Body Strength Development in Professional Australian Footballers.

PURPOSE: To compare resistance training using a velocity loss threshold with training to repetition failure on upper-body strength parameters in professional Australian footballers. METHODS: A total of 26 professional Australian footballers (23.9 [4.2] y, 189.9 [7.8] cm, 88.2 [8.8] kg) tested 1-repetition-maximum strength (FPmax) and mean barbell velocity at 85% of 1-repetition maximum on floor press (FPvel). They were then assigned to 2 training groups: 20% velocity loss threshold training (VL; n = 12, maximum-effort lift velocity) or training to repetition failure (TF; n = 14, self-selected lift velocity). Subjects trained twice per week for 3 weeks before being reassessed on FPmax and FPvel. Training volume (total repetitions) was recorded for all training sessions. No differences were present between groups on any pretraining measure. RESULTS: The TF group significantly improved FPmax (105.2-110.9 kg, +5.4%), while the VL group did not (107.5-109.2 kg, +1.6%) (P > .05). Both groups significantly increased FPvel (0.38-0.46 m·s-1, +19.1% and 0.37-0.42 m·s-1, +16.7%, respectively) with no between-groups differences evident (P > .05). The TF group performed significantly more training volume (12.2 vs 6.8 repetitions per session, P > .05). CONCLUSIONS: Training to repetition failure improved FPmax, while training using a velocity loss threshold of 20% did not. Both groups demonstrated similar improvements in FPvel despite the VL group completing 45% less total training volume than the TF group. The reduction in training volume associated with implementing a 20% velocity loss threshold may negatively impact the development of upper-body maximum strength while still enhancing submaximal movement velocity

The relationship between lower body stiffness and injury incidence in female netballers

© 2017 Informa UK Limited, trading as Taylor & Francis Group. The aim of this study was to provide contemporary information on injury rates in an elite and sub-elite netball population and to explore the relationship between lower body stiffness and lower body injuries. One elite and two sub-elite teams of female netballers (n = 29) performed the vertical hop test to assess active lower body stiffness (Kvert) and myometry to assess quasi-static stiffness. Lower body injuries were monitored via self-reporting and liaison with physiotherapists. Twelve lower body non-contact injuries were sustained by 10 players, equating to 11.29 lower body injuries per 1,000 exposure hours. The most commonly injured sites were the calf (33%) and ankle (25%). No significant differences between Kvert of injured and non-injured players were reported, however, injured elite players recorded significantly higher season mean quasi-static stiffness in the soleus (p = 0.037) and Achilles (p = 0.004) than non-injured elite players. Elite and sub-elite netball players recorded a higher injury incidence than previous reports of injuries in recreational netballers. Within the constraints of the study, relatively high stiffness of the soleus and Achilles appears to be related to lower body non-contact injury incidence in female netballers, particularly at the elite level. These results provide a basis for development of injury prevention strategies

Validity and interunit reliability of 10 Hz and 15 Hz GPS units for assessing athlete movement demands

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

The relationship between mechanical stiffness and athletic performance markers in sub-elite footballers

© 2017 Informa UK Limited, trading as Taylor & Francis Group. This study investigated the relationship between several measures of lower-body stiffness and physical performance variables in 22 sub-elite male football players (mean ± SD; 21.9 ± 1.5 yr; 1.79 ± 0.06 m; 72.2 ± 7.2 kg). The participants were assessed for individual muscle stiffness of the Rectus Femoris (RF), Biceps Femoris (BF) and Medial Gastrocnemius (MG) muscles and vertical stiffness (Kvert) was also assessed assessed running acceleration, maximal sprint speed, agility, vertical jumping and muscular strength. Pearson’s correlations quantified the relationships and participants were also separated into relatively stiff (SG) and compliant groups (CG) for each variable. When ranked by Kvert the SG exhibited superior performance during sprinting, agility, jumping and strength (p ≤ 0.05) and when ranked by RF stiffness, SG exhibited superior sprint, agility and drop jump performance (p ≤ 0.05), while MG and BF stiffness were not related to performance. Higher stiffness appears to be beneficial to athletic performance for football players and therefore it may be beneficial for practitioners working with athletes that are required to perform dynamic activities to consider the contribution of stiffness to athletic performance

Validity and reliability of three methods of stiffness assessment

© 2016 Background Stiffness is commonly assessed in relation to injury and athletic performance. The purpose of this research was to compare the validity and reliability of 3 in vivo methods of stiffness assessment using 1 cohort of participants. Methods To determine inter-day reliability, 15 female netballers were assessed for stiffness twice within 1 week using unilateral hopping (vertical stiffness), free oscillations of the calf, and myometry of various muscles of the triceps surae. To establish convergent construct validity, stiffness was compared to static and dynamic strength measurements. Results Test–retest stiffness results revealed that vertical stiffness produced moderate to high reliability results and myometry presented moderate to very high reliability. In contrast, the free oscillation technique displayed low to moderate reliability. Vertical stiffness demonstrated a significant correlation with rate of force development during a squat jump, whilst myometer stiffness measurements from 3 sites in the lower limb revealed significant correlations with isometric rate of force development. Further, significant negative correlations were evident between the eccentric utilisation ratio and various myometer stiffness results. No relationships were established between the free oscillation technique and any of the performance measurements. Conclusion These results suggest that vertical stiffness and myometry are valid and reliable methods for assessing stiffness