Matt Spencer

Physiological and Metabolic Responses of Repeated-Sprint Activities Specific to Field-Based Team Sports

Field-based team sports, such as soccer, rugby and hockey are popular worldwide. There have been many studies that have investigated the physiology of these sports, especially soccer. However, some fitness components of these field-based team sports are poorly understood. In particular, repeated-sprint ability (RSA) is one area that has received relatively little research attention until recent times. Historically, it has been difficult to investigate the nature of RSA, because of the unpredictability of player movements performed during field-based team sports. However, with improvements in technology, time-motion analysis has allowed researchers to document the detailed movement patterns of team-sport athletes. Studies that have published time-motion analysis during competition, in general, have reported the mean distance and duration of sprints during field-based team sports to be between 10–20m and 2–3 seconds, respectively. Unfortunately, the vast majority of these studies have not reported the specific movement patterns of RSA, which is proposed as an important fitness component of team sports. Furthermore, there have been few studies that have investigated the physiological requirements of one-off, short-duration sprinting and repeated sprints (≪10 seconds duration) that is specific to field-based team sports. This review examines the limited data concerning the metabolic changes occurring during this type of exercise, such as energy system contribution, adenosine triphosphate depletion and resynthesis, phosphocreatine degradation and resynthesis, glycolysis and glycogenolysis, and purine nucleotide loss. Assessment of RSA, as a training and research tool, is also discussed.

Time–motion analysis of elite field hockey, with special reference to repeated-sprint activity

Limited information exists about the movement patterns of field-hockey players, especially during elite competition. Time–motion analysis was used to document the movement patterns during an international field-hockey game. In addition, the movement patterns of repeated-sprint activity were investigated, as repeated-sprint ability is considered to be an important fitness component of team-sport performance. Fourteen members of the Australian mens field-hockey team (age 26±3 years, body mass 76.7±5.6 kg, [Vdot]O2max 57.9±3.6 ml · kg−1 · min−1; mean±s) were filmed during an international game and their movement patterns were analysed. The majority of the total player game time was spent in the low-intensity motions of walking, jogging and standing (46.5±8.1, 40.5±7.0 and 7.4±0.9%, respectively). In comparison, the proportions of time spent in striding and sprinting were 4.1±1.1 and 1.5±0.6%, respectively. Our criteria for ‘repeated-sprint’ activity (defined as a minimum of three sprints, with mean recovery duration between sprints of less than 21 s) was met on 17 occasions during the game (total for all players), with a mean 4±1 sprints per bout. On average, 95% of the recovery during the repeated-sprint bouts was of an active nature. In summary, the results suggest that the motion activities of an elite field-hockey competition are similar to those of elite soccer, rugby and Australian Rules football. In addition, the investigation of repeated-sprint activity during competition has provided additional information about the unique physiological demands of elite field-hockey performance.

The validity of a repeated sprint ability test

Many team sports require participants to repeatedly produce maximal or near maximal sprints of short duration (1-7s) with brief recovery periods, over an extended period of time (60-90 min). Therefore, an important fitness component for these sports is what is often termed repeated sprint ability (RSA). A variety of tests have been devised to assess RSA. However, while the reliability of some of these tests has been reported, there has been no published attempt to assess the validity of RSA tests. The purpose of the present paper was to assess the validity of a popular RSA test--the 5 x 6 s cycle test. Ten moderately-trained males (Mean+/-SD age: 23.6+/-3.0 yrs, mass: 71.8+/-7.4 kg, peak VO2: 46.32+/-4.16 ml.kg(-1)min(-1)) participated in the investigation. Following familiarisation, subjects reported to the laboratory at the same time of day, on three occasions, each separated by at least 48 hours. Testing consisted of a 5 x 6 s cycle test (5 x 6 s maximal sprints every 30 s), a graded exercise test (GXT) and a simulated game (3 x 15 min periods separated by five min). The simulated game consisted of a 1-min circuit that was repeated 15 times in each period. The circuit replicated typical movement patterns observed during motion analysis of field hockey games. Each circuit commenced with a 15-m maximum sprint through timing gates. Time to run 5, 10 and 15 m was recorded. Oxygen consumption was measured during both the GXT and the simulated game with a portable gas analysis system (Cosmed K4 b2, Italy). Correlation coefficients between dependent variables were calculated using Pearsons Product Moment (r). There was a significant correlation between power decrement during the 5 x 6 s cycle test and decrement in 15-m time across the three periods (r = 0.76, P<0.05), but not decrement in 10-m time (r = 0.54) or 5-m time (r = 0.42). These results suggest that the 5 x 6 s cycle test is valid for assessing the decrement in 15-m time, but not the decrement in 5 or 10m time. Thus, one measure of RSA (sprint decrement) appears to be specific to the test protocol, rather than a general quality. The most likely explanation is that the energy requirements of the 5 x 6 s cycle test more closely match those required to repeatedly run 15 m (mean time = 2.74 s) than to repeatedly run 10 m (mean time = 1.97 s) or 5 m (mean time = 1.13 s). It is therefore suggested that, while the 5 x 6 s cycle test is often used to assess RSA ability in a wide range of sports, it may need to be modified to reflect the common sprint distances found in specific sports.

Predictors of repeated-sprint ability in elite female hockey players

The ability to maintain maximal power over a series of sprints may depend, in part, on the resynthesis of PCr and the buffering of hydrogen ions (H+). As a result, repeated-sprint ability may be related to VO2peak and changes in plasma pH. Fourteen elite female field-hockey players (Mean +/- SD body mass: 61.1 +/- 5.9 kg and VO2pea: 55.7 +/- 3.2 mL x kg(-1) x min(-1)) participated in this investigation. Tests consisted of a repeated-sprint ability test (5 x 6-s all-out sprints every 30 s) and a VO2peak test. Capillary and venous blood was sampled before and after the 5 x 6-s cycle test for the determination of lactate concentration and pH. There were no significant correlations between VO2peak (mL x kg(-1) x min(-1)) and total work (J.kg(-1); r = 0.35), or power decrement (r = 0.30) during the repeated-sprint ability test. There was, however, a significant correlation between power decrement and change in plasma [H+] (r = 0.66; P < 0.05). The results of this study show that in a homogenous group of elite, team-sport athletes, VO2peak (mL x kg(-1) x min(-1)) is not a strong predictor of repeated-sprint ability. However, in this group, there is a significant correlation between change in plasma [H+] and repeated-sprint ability.

Age-related differences in repeated-sprint ability in highly trained youth football players

Abstract In this study, we investigated the age-related differences in repeated-sprint ability and blood lactate responses in 134 youth football players. Players from the development programme of a professional club were grouped according to their respective under-age team (U-11 to U-18). Following familiarization, the participants performed a repeated-sprint ability test [6 × 30-m sprints 30 s apart, with active recovery (2.0–2.2 m · s−1) between sprints]. The test variables were total time, percent sprint decrement, and post-test peak lactate concentration. Total time improved from the U-11 to U-15 age groups (range 33.15 ± 1.84 vs. 27.25 ± 0.82 s), whereas no further significant improvements were evident from U-15 to U-18. No significant differences in percent sprint decrement were reported among groups (range 4.0 ± 1.0% to 5.5 ± 2.1%). Post-test peak lactate increased from one age group to the next (range 7.3 ± 1.8 to 12.6 ± 1.6 mmol · l−1), but remained constant when adjusted for age-related difference in body mass. Peak lactate concentration was moderately correlated with sprint time (r = 0.70, P > 0.001). Our results suggest that performance in repeated-sprint ability improves during maturation of highly trained youth football players, although a plateau occurs from 15 years of age. In contrast to expectations based on previous suggestions, percent sprint decrement during repeated sprints did not deteriorate with age.

Longitudinal assessment of the effects of field-hockey training on repeated sprint ability

Repeated-sprint ability is thought to be an important fitness component of team sports. However, little is known about the effect sport-specific training has on this fitness component. Therefore, the purpose of this study was to investigate the effects of field-hockey specific training on repeated-sprint ability, plasma hypoxanthine (Hx) concentration and other blood parameters in 18 elite female field-hockey players. All subjects performed a repeated-sprint ability test on a cycle ergometer (5 x 6-sec maximal sprints every 30 secs) before and after seven weeks of training, designed to improve repeated-sprint ability. Following training, there was a significant (P< 0.05) increase in absolute total work (20.73+/-2.00 to 21.15+/-2.07 kJ, mean+/-SD). However, there was no significant change in total work when expressed per kg of body mass (341.3+/-16.4 to 345.5+/-18.8 J x kg(-1)). In addition, training resulted in a significant (P< 0.05) decrease in change values (peak-rest values) for Hx (8.2+/-3.8 to 5.5+/-2.7 micromol x L(-1)) and hydrogen ion concentration (22.8+/-5.2 to 19.1+/-5.1 nmol x L(-1)). The significant increase in absolute total work following seven weeks of field-hockey specific training was most likely due to an increase in lean muscle mass. The significant decrease in plasma Hx concentration (post-test minus rest values) following seven weeks of field hockey-specific training provides evidence that Hx production and/or efflux from the muscle are reduced. Therefore, one adaptation of sport-specific repeated-sprint training may be to conserve the purine nucleotide pool.

Variability and Predictability of Performance Times of Elite Cross-Country Skiers

UNLABELLED Analyses of elite competitive performance provide useful information for research and practical applications. PURPOSE Here the authors analyze performance times of cross-country skiers at international competitions (World Cup, World Championship, and Olympics) in classical and free styles of womens and mens distance and sprint events, each with a total of 410-569 athletes competing in 1-44 races at 15-25 venues from seasons 2002 to 2011. METHODS A linear mixed model of race times for each event provided estimates of within-athlete race-to-race variability expressed as a coefficient of variation (CV) after adjustment for fixed or random effects of snow conditions, altitude, race length, and competition terrain. RESULTS Within-athlete variability was similar for men and women over various events for all athletes (CV of 1.5-1.8%) and for the annual top-10 athletes (1.1-1.4%). Observed effects of snow conditions and altitude on mean time were substantial (~2%) but mostly unclear, owing to large effects of terrain (CV of 4-10% in top-10 analyses). Predictability of performance was extremely high for all athletes (intraclass correlations of .90-.96) but only trivial to poor for top-10 athletes (men .00-.03, women .03-.35). CONCLUSION The race-to-race variability of top-ranked skiers is similar to that of other elite endurance athletes. Estimates of the smallest worthwhile performance enhancement (0.3× within-athlete variability) will help researchers and practitioners evaluate strategies affecting performance of elite skiers.

Improving the Value of Fitness Testing for Football

One of the challenges for sports scientists working in football is to balance the needs for routine fitness testing with daily fatigue and well-being monitoring to best manage the physical preparation of players. In this commentary, the authors examine contemporary issues of fitness testing in football to identify ways of improving the value of routine testing and monitoring. A testing program must be well planned and organized to ensure that the results are useful. Different tests can be employed for younger and older players. A rigorous approach to analysis and interpretation of results is desirable, and database management must address both short- and long-term requirements of players, staff, and programs.

High-Intensity Events in International Women’s Team Handball Matches

PURPOSE International womens team handball is a physically demanding sport and is intermittent in nature. The aim of the study was to profile high-intensity events (HIEs) in international womens team handball matches with regard to playing positions. METHODS Twenty female national-team handball players were equipped with inertial movement units (OptimEye S5, Catapult Sports, Australia) in 9 official international matches. Players were categorized in 4 different playing positions: backs, wings, pivots, and goalkeepers (GKs). PlayerLoad™, accelerations (Acc), changes of direction (CoD), decelerations (Dec), and the sum of the latter 3, HIEs, were extracted from raw-data files using the manufacturers software. All Acc, Dec, CoD, and HIEs >2.5 m/s were included. Data were log-transformed and differences were standardized for interpretation of magnitudes and reported with effect-size statistics. RESULTS Mean numbers of events were 0.7 ± 0.4 Acc/min, 2.3 ± 0.9 Dec/min, and 1.0 ± 0.4 CoD/min. Substantial differences between playing positions, ranging from small to very large, were found in the 3 parameters. Backs showed a most likely greater frequency for HIE/min (5.0 ± 1.1 HIE/min) than all other playing positions. Differences between playing positions were also apparent in PlayerLoad/min. CONCLUSION HIEs in international womens team handball are position specific, and the overall intensity depends on the positional role within a team. Specific HIE and intensity profiles from match play provide useful information for a better understanding of the overall game demands and for each playing position.

Effect of traditional and resisted sprint training in highly trained female team handball players.

UNLABELLED Fast acceleration is an important performance factor in handball. In addition to traditional sprint training (TST), resisted-sprint training (RST) is a method often used to improve acceleration. However, studies on RST show conflicting results, and underlying mechanisms have not been studied. PURPOSE To compare the effects of RST, by sled towing, against TST on sprint performance and muscle architecture. METHODS Participants (n=18) were assigned to either RST or TST and completed 2 training sessions of RST or TST per week (10 wk), in addition to their normal team training. Sprint tests (10 and 30 m) and measurements of muscle architecture were performed pre- and posttraining. RESULTS Beneficial effects were found in the 30-m-sprint test for both groups (mean; ±90% CL: TST=-0.31; ±0.19 s, RST=-0.16; ±0.13 s), with unclear differences between the groups. Only TST had a beneficial effect on 10-m time (-0.04; ±0.04 s), with a likely difference between the 2 groups (85%, ES=0.60). Both groups had a decrease in pennation angle (-6.0; ±3.3% for TST and -2.8; ±2.0% for RST), which had a nearly perfect correlation with percentage change in 10-m-sprint performance (r=.92). A small increase in fascicle length (5.3; ±3.9% and 4.0; ±2.1% for TST and RST, respectively) was found, with unclear differences between groups. DISCUSSION TST appears to be more effective than RST in enhancing 10-m-sprint time. Both groups showed similar effects in 30-m-sprint time. A similar, yet small, effect of sprint training on muscle architecture was observed in both groups.