Purpose: To investigate the strengths and limitations of different indicators to measure physical load. Furthermore, indicators were evaluated for discrimination between performance levels and playing positions. Methods: Ninety positional match files from 70 elite players and 91 match files from 69 subelite players were collected during 14 official under-18 matches using a local position measurement system. Indicators are calculated from speed, absolute acceleration (acc-abs), or percentage acceleration (acc-%). The acc-% describes the level of acceleration depending on the maximal voluntary acceleration (a max) for each initial running speed. Effect sizes (ES) were used to determine discriminative ability. Results: The number of high accelerations largely depended on the method (absolute threshold [>3 m·s−2 and >4 m·s−2] 120 and 59 efforts; high percentage threshold [>75% a max] 84 efforts). Only a small number of highly accelerated efforts reached speeds considered high-speed running (>19.8 km·h−1: 32.6%). More high acc-% exists from initial running speed >2 m·s−1 (23.0) compared with acc-abs (>3 m·s−2 14.4, >4 m·s−2 5.9). Elite players achieve higher values in most performance indicators, with ES being highest for the number of high acc-% (ES = 0.91) and high acc-abs (>3 m·s−2 ES = 0.86, >4 m·s−2 ES = 0.87), as well as for covered distance in jogging (ES = 0.94). Conclusions: Estimated physical load, discriminative ability of physical indicators, and positional requirements largely depend on the applied method. A combination of speed-based and acc-% methods is recommended to get a comprehensive view.
Karin Fischer-Sonderegger, Wolfgang Taube, Martin Rumo and Markus Tschopp
Joel Garrett, Stuart R. Graham, Roger G. Eston, Darren J. Burgess, Lachlan J. Garrett, John Jakeman and Kevin Norton
Purpose: To compare the sensitivity of a submaximal run test (SRT) with a countermovement-jump test (CMJ) to provide an alternative method of measuring neuromuscular fatigue (NMF) in high-performance sport. Methods: A total of 23 professional and semiprofessional Australian rules football players performed an SRT and CMJ test prematch and 48 and 96 h postmatch. Variables from accelerometers recorded during the SRT were player load 1D up (vertical vector), player load 1D side (mediolateral vector), and player load 1D forward (anteroposterior vector). Meaningful difference was examined through magnitude-based inferences (effect size [ES]), with reliability assessed as typical error of measurements expressed as coefficient of variance. Results: A small decrease in CMJ height, ES −0.43 ± 0.39 (likely), was observed 48 h postmatch before returning to baseline 96 h postmatch. This was accompanied by corresponding moderate decreases in the SRT variables player load 1D up, ES −0.60 ± 0.51 (likely), and player load 1D side, ES −0.74 ± 0.57 (likely), 48 h postmatch before also returning to prematch baseline. Conclusion: The results suggest that in the presence of NMF, players use an alternative running profile to produce the same external output (ie, time). This indicates that changes in accelerometer variables during an SRT can be used as an alternative method of measuring NMF in high-performance Australian rules football and provides a flexible option for monitoring changes in the recovery phase postmatch.
Paula B. Costa, Scott R. Richmond, Charles R. Smith, Brad Currier, Richard A. Stecker, Brad T. Gieske, Kimi Kemp, Kyle E. Witherbee and Chad M. Kerksick
Synchronized swimming is a sport that requires high levels of strength, power, and endurance, as well as artistic skill to perform in an aquatic environment. Purpose: The purpose of this study was to identify physiological characteristics and dietary habits of collegiate synchronized swimmers. Methods: A total of 21 female participants (mean [SD] age = 20.4 [1.6] y, height = 168.0 [4.9] cm, and weight = 64.4 [8.7] kg) performed resting metabolic rate test. Body composition was determined using skinfolds (4-site and 7-site) and dual-energy X-ray absorptiometry (DEXA). Dietary intake was assessed using 4-d dietary records. Results: Resting metabolic rate was 110.9 (10.5) kJ/kg normalized to body weight and calculated relative daily caloric intake was 121.4 (42.3) kJ/kg. Estimated energy availability ranged from 109.1 (52.1) to 126.7 (52.6) kJ/kg fat-free mass per day and was correlated (P = .045) to resting metabolic rate. Percentage body fat measured using DEXA (28.7% [4.8%] fat) was higher than both 4-site (25.7% [4.8%] fat, P = .001) and 7-site (25.3% [4.7%] fat, P = .001) skinfold values. No significant correlations were reported between bone mineral density, body composition, and dietary intake data. Conclusions: Synchronized swimmers have similar body composition and training habits as other competitive aquatic athletes. Dietary intake data revealed low energy availability and lower than recommended macronutrient levels.
Matthew D. DeLang, Mehdi Rouissi, Nicola L. Bragazzi, Karim Chamari and Paul A. Salamh
Purpose: Limb dominance and consequent between-limbs muscle strength in soccer players should be explored to determine a standard musculoskeletal profile to maintain and establish during screening protocols and postinjury rehabilitation. The primary aim of this review was to identify dominant- vs non-dominant-lower-extremity muscle-strength characteristics of healthy soccer players, with secondary aims to consider available between-limbs outcome measures and directions for future research. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Five electronic databases were used for study identification with guidance from a medical librarian. Inclusion criteria consisted of studies employing a cross-sectional design assessing soccer players of all ages, genders, and levels of play that identified limb dominance and associated lower-extremity muscle strength as a main purpose of the experiment. Results: The literature search identified 3471 articles. After screening titles, abstracts, and full texts, 17 articles were included in the review. Peak torques and hamstring-to-quadriceps ratios via isokinetic dynamometry were commonly used, and subsequent meta-analyses were conducted to yield remarkable between-limbs symmetry. Additional results of individual studies also demonstrate symmetry, except 1 article of velocity-dependent measures that reported greater strength in the dominant limb. Conclusions: In soccer, between-limbs muscle strength measured by maximal isokinetic dynamometry demonstrates symmetry across ages, genders, and levels of play. Future testing using alternative measures that more specifically replicate the movement demands of soccer players may further classify between-limbs characteristics.
Montassar Tabben, Daniele Conte, Monoem Haddad and Karim Chamari
Purpose: To assess the technical and tactical demands of elite karate athletes in relation to 3 match sequences (ie, advantage, disadvantage, and drawing) and match outcome (ie, win/defeat).Methods: One hundred twenty elite seniors’ (60 men and 60 women) World Karate Federation combats were analyzed during 2 World Championships (2012 and 2014). Specific karate attributes (strategy, technique, tactic, target, and effectiveness) were evaluated and classified into 3 sequences: advantage, disadvantage, and drawing. Results: Karatekas performed more combination techniques in disadvantage sequences than in drawing sequences (P = .011). A higher number of timed-attack actions were reported during advantage sequences than during drawing sequences (P = .048). Winners of the whole combat had higher lower-limb technique rate (1.0 [0.9] vs 0.1 [0.3]; P = .044) and less rate of timed attack (0.3 [0.5] vs 0.6 [1.0]; P = .030) than defeated karatekas during advantage and drawing sequences, respectively. Conclusions: Winners used higher lower-limb technique and less timed-attack rates than defeated karatekas in advantage and drawing sequences, respectively. Indeed, using lower-limb technique during advantageous situations could be a powerful strategy to increase the lead. Therefore, it seems fundamental for coaches of top elite karatekas to put their athletes in simulated situations and push them to increase their use of lower-limb techniques.
Richard Johnston, Roisin Cahalan, Laura Bonnett, Matthew Maguire, Alan Nevill, Philip Glasgow, Kieran O’Sullivan and Thomas Comyns
Purpose: To determine the association between training-load (TL) factors, baseline characteristics, and new injury and/or pain (IP) risk in an endurance sporting population (ESP). Methods: Ninety-five ESP participants from running, triathlon, swimming, cycling, and rowing disciplines initially completed a questionnaire capturing baseline characteristics. TL and IP data were submitted weekly over a 52-wk study period. Cumulative TL factors, acute:chronic workload ratios, and exponentially weighted moving averages were calculated. A shared frailty model was used to explore time to new IP and association to TL factors and baseline characteristics. Results: 92.6% of the ESP completed all 52 wk of TL and IP data. The following factors were associated with the lowest risk of a new IP episode: (a) a low to moderate 7-d lag exponentially weighted moving averages (0.8–1.3: hazard ratio [HR] = 1.21; 95% confidence interval [CI], 1.01–1.44; P = .04); (b) a low to moderate 7-d lag weekly TL (1200–1700 AU: HR = 1.38; 95% CI, 1.15–1.65; P < .001); (c) a moderate to high 14-d lag 4-weekly cumulative TL (5200–8000 AU: HR = 0.33; 95% CI, 0.21–0.50; P < .001); and (d) a low number of previous IP episodes in the preceding 12 mo (1 previous IP episode: HR = 1.11; 95% CI, 1.04–1.17; P = .04). Conclusions: To minimize new IP risk, an ESP should avoid high spikes in acute TL while maintaining moderate to high chronic TLs. A history of previous IP should be considered when prescribing TLs. The demonstration of a lag between a TL factor and its impact on new IP risk may have important implications for future ESP TL analysis.
Barry S. Mason, Viola C. Altmann and Victoria L. Goosey-Tolfrey
Purpose: To determine the effect of trunk and arm impairments on physical and technical performance during wheelchair rugby (WR) competition. Methods: Thirty-one highly trained WR players grouped according to their trunk (no trunk [NT]; some trunk [T] function) and arm impairments (poor, moderate, and good arm function) participated in 5 WR matches. Players’ physical (wheelchair mobility) and technical (ball handling) activities were analyzed using an indoor tracking system and video analysis, respectively. Results: Trunk impairment explained some of the variance in physical (10.6–23.5%) and technical (16.2–33.0%) performance. T covered more distance, had more possession, scored more goals, and received and made more passes yet spent less time at low speeds and performed fewer inbounds than NT (≤.05). Arm impairment explained some of the variance in all physical (16.7–47.0%) and the majority of technical (13.1–53.3%) performance measures. Moderate and good arm function covered more distance, reached higher peak speeds, spent more time in higher speed zones, scored more goals, had more possession, and received and made more passes, with a higher percentage of 1-handed and long passes, than poor arm function. Good arm function also received more passes and made a higher percentage of 1-handed passes and defensive blocks than moderate arm function (P ≤ .05). Conclusions: Arm impairment affects a greater number of physical and technical measures of performance specific to WR than trunk impairment during competition. Having active finger function (good arm function) yielded no further improvements in physical performance but positively influenced a small number of technical skills.
Gareth N. Sandford, Sian V. Allen, Andrew E. Kilding, Angus Ross and Paul B. Laursen
Purpose: In recent years (2011–2016), men’s 800-m championship running performances have required greater speed than previous eras (2000–2009). The “anaerobic speed reserve” (ASR) may be a key differentiator of this performance, but profiles of elite 800-m runners and their relationship to performance time have yet to be determined. Methods: The ASR—determined as the difference between maximal sprint speed (MSS) and predicted maximal aerobic speed (MAS)—of 19 elite 800- and 1500-m runners was assessed using 50-m sprint and 1500-m race performance times. Profiles of 3 athlete subgroups were examined using cluster analysis and the speed reserve ratio (SRR), defined as MSS/MAS. Results: For the same MAS, MSS and ASR showed very large negative (both r = −.74 ± .30, ±90% confidence limits; very likely) relationships with 800-m performance time. In contrast, for the same MSS, ASR and MAS had small negative relationships (both r = −.16 ± .54; possibly) with 800-m performance. ASR, 800-m personal best, and SRR best defined the 3 subgroups along a continuum of 800-m runners, with SRR values as follows: 400–800 m ≥ 1.58, 800 m ≤ 1.57 to ≥ 1.48, and 800–1500 m ≤ 1.47 to ≥ 1.36. Conclusion: MSS had the strongest relationship with 800-m performance, whereby for the same MSS, MAS and ASR showed only small relationships to differences in 800-m time. Furthermore, the findings support the coaching observation of three 800-m subgroups, with the SRR potentially representing a useful and practical tool for identifying an athlete’s 800-m profile. Future investigations should consider the SRR framework and its application for individualized training approaches in this event.
Ben T. Stephenson, Eleanor Hynes, Christof A. Leicht, Keith Tolfrey and Victoria L. Goosey-Tolfrey
Purpose: To gain an exploratory insight into the relation between training load (TL), salivary secretory immunoglobulin A (sIgA), and upper respiratory tract illness (URI) in elite paratriathletes. Methods: Seven paratriathletes were recruited. Athletes provided weekly saliva samples for the measurement of sIgA over 23 consecutive weeks (February to July) and a further 11 consecutive weeks (November to January). sIgA was compared to individuals’ weekly training duration, external TL, and internal TL, using time spent in predetermined heart-rate zones. Correlations were assessed via regression analyses. URI was quantified via weekly self-report symptom questionnaire. Results: There was a significant negative relation between athletes’ individual weekly training duration and sIgA secretion rate (P = .028), with changes in training duration accounting for 12.7% of the variance (quartiles: 0.2%, 19.2%). There was, however, no significant relation between external or internal TL and sIgA parameters (P ≥ .104). There was no significant difference in sIgA when URI was present or not (101% vs 118% healthy median concentration; P ≥ .225); likewise, there was no difference in sIgA when URI occurred within 2 wk of sampling or not (83% vs 125% healthy median concentration; P ≥ .120). Conclusions: Paratriathletes’ weekly training duration significantly affects sIgA secretion rate, yet the authors did not find a relation between external or internal TL and sIgA parameters. Furthermore, it was not possible to detect any link between sIgA and URI occurrence, which throws into question the potential of using sIgA as a monitoring tool for early detection of illness.
Patrick Ward, Johann Windt and Thomas Kempton
The application of scientific principles to inform practice has become increasingly common in professional sports, with increasing numbers of sport scientists operating in this area. The authors believe that in addition to domain-specific expertise, effective sport scientists working in professional sport should be able to develop systematic analysis frameworks to enhance performance in their organization. Although statistical analysis is critical to this process, it depends on proper data collection, integration, and storage. The purpose of this commentary is to discuss the opportunity for sport-science professionals to contribute beyond their domain-specific expertise and apply these principles in a business-intelligence function to support decision makers across the organization. The decision-support model aims to improve both the efficiency and the effectiveness of decisions and comprises 3 areas: data collection and organization, analytic models to drive insight, and interface and communication of information. In addition to developing frameworks for managing data systems, the authors suggest that sport scientists’ grounding in scientific thinking and statistics positions them to assist in the development of robust decision-making processes across the organization. Furthermore, sport scientists can audit the outcomes of decisions made by the organization. By tracking outcomes, a feedback loop can be established to identify the types of decisions that are being made well and the situations where poor decisions persist. The authors have proposed that sport scientists can contribute to the broader success of professional sporting organizations by promoting decision-support services that incorporate data collection, analysis, and communication.