Validity and Reliability of a Submaximal Intermittent Running Test in Elite Australian Football Players.

Veugelers, KR, Naughton, GA, Duncan, CS, Burgess, DJ, and Graham, SR. Validity and reliability of a submaximal intermittent running test in elite Australian football players. J Strength Cond Res 30(12): 3347-3353, 2016-The aim of this article was to determine the validity and reliability of a submaximal intermittent running (SIR) test in elite Australian rules football (ARF) players. Heart rate (HR) responses of 38 elite ARF players to both the SIR and the yo-yo intermittent recovery 2 (YYIR2) tests were compared over 2 trials. Linear regression analysis was used to examine the relationship between SIR test HR responses and YYIR2 test performance. Heart rate responses of 25 elite ARF players to the SIR test were monitored over 3 trials. Day-to-day reliability was determined using intraclass correlation coefficient (ICC), typical error of measurement, coefficient of variation (CV), and smallest worthwhile change. Large inverse correlations were reported between 2-, 3-, and 4-minute HR during the SIR test and YYIR2 test distance (r = -0.58 to -0.61, p < 0.01). Heart rate recovery after 2 and 3 minutes of the SIR test was moderately correlated to YYIR2 distance (r = 0.32-0.35, p ≤ 0.05). Strong correlations for ICC (r = 0.90-0.97) and low CV (1.3-9.2%) were reported for all HR variables. Monitoring HR during the SIR test is a valid and reliable indicator of YYIR2 test performance in elite ARF players. These findings support the use of the SIR test as a regular and non-fatiguing indicator of intermittent running capacity.

GPS and Injury Prevention in Professional Soccer.

This study investigated the relationship between GPS variables measured in training and gameplay and injury occurrences in professional soccer. Nineteen professional soccer players competing in the Australian Hyundai A-League were monitored for 1 entire season using 5 Hz Global Positioning System (GPS) units (SPI-Pro GPSports) in training sessions and preseason games. The measurements obtained were total distance, high-intensity running distance, very-high-intensity running distance, new body load, and meters per minute. Noncontact soft tissue injuries were documented throughout the season. Players' seasons were averaged over 1- and 4-week blocks according to when injuries occurred. These blocks were compared with each other and with players' seasonal averages. Players performed significantly higher meters per minute in the weeks preceding an injury compared with their seasonal averages (+9.6 and +7.4% for 1- and 4-week blocks, respectively) (p < 0.01), indicating an increase in training and gameplay intensity leading up to injuries. Furthermore, injury blocks showed significantly lower average new body load compared with seasonal averages (-15.4 and -9.0% for 1- and 4-week blocks, respectively) (p < 0.01 and p = 0.01). Periods of relative underpreparedness could potentially leave players unable to cope with intense bouts of high-intensity efforts during competitive matches. Although limited by Fédération Internationale de Football Association regulations, the results of this study isolated 2 variables predicting soft tissue injuries for coaches and sports scientists to consider when planning and monitoring training.

Movement analysis of Australian national league soccer players using global positioning system technology.

Player activity profiles of match play provide valuable information for optimal athlete training prescriptions, competition strategies, and managing load and recovery and are currently lacking in elite Australian-league (A-League) soccer. The aims of the study were, therefore, to (a) determine match activity profiles for elite A-League soccer players and make match-half and positional comparisons and (b) examine the effect of situational factors including evolving match status (drawing, winning, or losing) and goals being scored and conceded on selected match activity profile variables. Global positioning system tracking devices were used to determine activity profiles of 19 elite male adult soccer players during 8 preseason matches (n = 95 files). Total distance, average speed, high-intensity running (HIR) distance, and very high-intensity running distance decreased from the first to the second half by 7.92, 9.47, 10.10, and 10.99%, respectively. Midfielders covered 11.69% more total distance, 28.08% more HIR distance, and had a 10.93% higher average speed than defenders (p ≤ 0.05; d = 1.90, 1.03, and 1.83, respectively). Attackers performed 27.50 and 30.24% less medium accelerations than defenders and midfielders, respectively (p < 0.01; d = 1.54, and 1.73). When the team was winning, average speed was 4.17% lower than when the team was drawing (p ≤ 0.05, d = 0.32). Scoring or conceding goals did not appear to affect HIR. This study adds to limited knowledge of match demands in elite A-League soccer. The match activity profiles provide descriptive benchmarks that could be used to make comparisons with other elite level soccer populations while also providing a framework for game-specific training prescription, competition strategy, and load management. The generalization that defenders experience a relatively lower match load may be questionable given their relatively high acceleration and deceleration demands.

Mid-femur geometry and biomechanical properties in 15- to 18-yr-old female athletes.

PURPOSE: Right-leg mid-femur geometry and biomechanical indices of bone strength were compared among elite cyclists (CYC), runners (RUN), swimmers (SWIM), triathletes (TRI), and controls (C)-10 subjects per group. METHODS: Bone cross-sectional areas (CSA), volumes (Vol), and cross-sectional moments of inertia (CSMI) were assessed by magnetic resonance imaging (MRI), and cortical volumetric bone density (volBMD) was determined as the quotient of DXA-derived bone mineral content (BMC) and MRI-derived cortical bone volume. Bone strength index (BSI) was calculated as the product of cortical volBMD and CSMI. RESULTS: RUN had higher (P < 0.05) size- (femur length and body mass) adjusted (ANCOVA) cortical CSA than C, SWIM, and CYC; and higher size, age, and years of sport-specific training- (YST) adjusted cortical CSA than SWIM and CYC. TRI had higher (P < 0.05) size-adjusted CSA than SWIM. SWIM and CYC had significantly larger (P < 0.05) size-adjusted medullary cavity CSA than RUN and TRI, and the difference between CYC and RUN persisted after additional adjustment for age and YST. RUN had significantly (P < 0.05) greater size-adjusted CSMI and BSI than C, SWIM, and CYC; and higher size, age, and YST-adjusted CSMI and BSI than SWIM and CYC. Mid-femur areal bone mineral density (BMD) was significantly (P < 0.05) higher for RUN compared with CYC only, but there were no other differences among groups for BMC, bone volumes, or volumetric total or cortical BMD. CONCLUSIONS: Running, a weight-bearing exercise, is associated with more favorable geometric and biomechanical characteristics in relation to bone strength, compared with the weight supported activities of swimming and cycling. Differences may reflect skeletal adaptations to the specific mechanical-loading patterns inherent in these sports.

Bone mineral density in adolescent female athletes: relationship to exercise type and muscle strength.

PURPOSE: This study investigated the influence of different exercise types and differences in anatomical distribution of mechanical loading patterns on bone mineral density (BMD) in elite female cyclists, runners, swimmers, triathletes, and controls (N = 15 per group). Associations between leg strength and BMD were also examined. METHODS: Areal BMD (g x cm(-2)) was assessed by duel-energy x-ray absorptiometry (DXA) (total body (TB), lumbar spine (LS), femoral neck (FN), legs, and arms). Right knee flexion and extension strength was measured using a Cybex Norm isokinetic dynamometer at 60 degrees x s(-1). RESULTS: Runners had significantly higher unadjusted TB, LS, FN, and leg BMD than controls (P < 0.05); higher TB, FN, and leg BMD than swimmers (P < 0.05); and greater leg BMD than cyclists (P < 0.05). Absolute knee extension strength was significantly (P < 0.01) correlated (0.33 < or = r < or = 0.44) with TB, FN, LS, and leg BMD for all groups combined. Weaker but still significant correlations (0.28 < or = r < or = 0.33) existed for normalized (per leg lean tissue mass) knee extension strength and all BMD sites, except FN BMD. There were no significant correlations between absolute or normalized knee flexion strength and any of the BMD variables. Absolute knee extension strength was entered as the second independent predictor for LS and leg BMD in stepwise multiple linear regression analysis (MLRA), accounting for increments of 4% and 12%, respectively, in total explained variation. CONCLUSION: We conclude that running, a weight bearing exercise, is associated with larger site-specific BMD than swimming or cycling, that the generalized anatomical distribution of loads in triathlon appears not to significantly enhance total body BMD status, and that knee extension strength is only a weak correlate and independent predictor of BMD in adolescent females.