Benjamin J. Dascombe

Effect of direct supervision of a strength coach on measures of muscular strength and power in young rugby league players

The purpose of the present study was to examine the influence of direct supervision on muscular strength, power, and running speed during 12 weeks of resistance training in young rugby league players. Two matched groups of young (16.7 ± 1.1 years [mean ± SD]), talented rugby league players completed the same periodized resistance-training program in either a supervised (SUP) (N = 21) or an unsupervised (UNSUP) (N = 21) environment. Measures of 3 repetition maximum (3RM) bench press, 3RM squat, maximal chin-ups, vertical jump, 10– and 20-m sprints, and body mass were completed pretest (week 0), midtest (week 6), and posttest (week 12) training program. Results show that 12 weeks of periodized resistance training resulted in an increased body mass, 3RM bench press, 3RM squat, maximum number of chin-ups, vertical jump height, and 10– and 20-m sprint performance in both groups (p < 0.05). The SUP group completed significantly more training sessions, which were significantly correlated to strength increases for 3RM bench press and squat (p < 0.05). Furthermore, the SUP group significantly increased 3RM squat strength (at 6 and 12 weeks) and 3RM bench press strength (12 weeks) when compared to the UNSUP group (p < 0.05). Finally, the percent increase in the 3RM bench press, 3RM squat, and chin-upmax was also significantly greater in the SUP group than in the UNSUP group (p < 0.05). These findings show that the direct supervision of resistance training in young athletes results in greater training adherence and increased strength gains than does unsupervised training.

Nutritional supplementation habits and perceptions of elite athletes within a state-based sporting institute

The purpose of this investigation was to examine the nutritional supplement intake of athletes from a state-based sports institute. Athletes (n=72) from seven sports (kayaking, field hockey, rowing, waterpolo, swimming, athletics and netball) completed a questionnaire detailing their daily usage and rationale therefore. The large majority (63/72; 87.5+/-12.5%) of surveyed athletes reported using nutritional supplements, with no difference between female (31/36; 86.1+/-13.9%) and male (32/36; 88.9+/-11.1%) athletes. Kayakers (6.0+/-2.9) consumed a higher number of nutritional supplements than swimmers (4+/-2.2), field hockey (1.5+/-1.0), rowing (2.4+/-1.4), waterpolo (2.3+/-2.4), athletics (2.5+/-1.9) and netball (1.7+/-1.0) athletes. The athletes believed that nutritional supplements are related to performance enhancements (47/72; 65.3%), positive doping results (45/72; 62.5%), and that heavy training increases supplement requirements (47/72; 65.3%). The cohort was equivocal as to their health risks (40/72; 55.6%) or their need with a balanced diet (38/72; 52.8%). The most popular supplements were minerals (33/72; 45.8%), vitamins (31/72; 43.1%), other (23/72; 31.9%), iron (22/72; 30.6%), caffeine (16/72; 22.2%), protein (12/72; 16.7%), protein-carbohydrate mix (10/72; 13.9%), creatine (9/72; 12.5%) and glucosamine (3/72; 4.2%). The majority of supplementing athletes (n=63) did not know their supplements active ingredient (39/63; 61.9%), side effects (36/63; 57.1%) or mechanism of action (34/63; 54.0%) and admitted to wanting additional information (36/63; 57.0%). Only half of the athletes knew the recommended supplement dosages (33/63; 52.4%). The performance enhancing perception may explain the large proportion of athletes that reported using nutritional supplements, despite over half of the athletes believing that supplements are not required with a balanced diet and can cause positive doping violations.

Accuracy and Reliability of GPS Devices for Measurement of Sports-Specific Movement Patterns Related to Cricket, Tennis, and Field-Based Team Sports

Abstract Vickery, WM, Dascombe, BJ, Baker, JD, Higham, DG, Spratford, WA, and Duffield, R. Accuracy and reliability of GPS devices for measurement of sports-specific movement patterns related to cricket, tennis, and field-based team sports. J Strength Cond Res 28(6): 1697–1705, 2014—The aim of this study was to determine the accuracy and reliability of 5, 10, and 15 Hz global positioning system (GPS) devices. Two male subjects (mean ± SD; age, 25.5 ± 0.7 years; height, 1.75 ± 0.01 m; body mass, 74 ± 5.7 kg) completed 10 repetitions of drills replicating movements typical of tennis, cricket, and field-based (football) sports. All movements were completed wearing two 5 and 10 Hz MinimaxX and 2 GPS-Sports 15 Hz GPS devices in a specially designed harness. Criterion movement data for distance and speed were provided from a 22-camera VICON system sampling at 100 Hz. Accuracy was determined using 1-way analysis of variance with Tukeys post hoc tests. Interunit reliability was determined using intraclass correlation (ICC), and typical error was estimated as coefficient of variation (CV). Overall, for the majority of distance and speed measures, as measured using the 5, 10, and 15 Hz GPS devices, were not significantly different (p > 0.05) to the VICON data. Additionally, no improvements in the accuracy or reliability of GPS devices were observed with an increase in the sampling rate. However, the CV for the 5 and 15 Hz devices for distance and speed measures ranged between 3 and 33%, with increasing variability evident in higher speed zones. The majority of ICC measures possessed a low level of interunit reliability (r = −0.35 to 0.39). Based on these results, practitioners of these devices should be aware that measurements of distance and speed may be consistently underestimated, regardless of the movements performed.

The Effects of Whole-body Compression Garments on Prolonged High-intensity Intermittent Exercise

Sear, JA, Hoare, TK, Scanlan, AT, Abt, GA, and Dascombe, BJ. The effects of whole-body compression garments on prolonged high-intensity intermittent exercise. J Strength Cond Res 24(7): 1901-1910, 2010-The current study investigated the effects of wearing whole-body compression garments (WBCGs) on prolonged high-intensity intermittent exercise (PHIIE) performance. Eight male team-sport athletes ([&OV0398; ± SD] 20.6 ± 1.2 years; 72.9 ± 5.9 kg; 57.5 ± 3.7 ml·kg−1·min−1) completed a prescribed 45-minute PHIIE protocol on a nonmotorized treadmill in randomly assigned WBCG and control (typical soccer apparel) conditions. Subjects were given verbal and visual cues for movement categories, and they followed set target speeds, except when instructed of a variable run or sprint where the aim was to run as fast as possible. Total distance, velocity-specific distance, and high-intensity self-paced running speeds were taken as performance indicators. Heart rate, &OV0312;o2, tissue oxygenation index (TOI), and tissue hemoglobin index (nTHi) were continuously monitored across the protocol. Blood-lactate concentration ([BLa−]) was measured every 15 minutes. Magnitude-based inferences suggested that wearing WBCGs provided moderate strength likely improvements in total distance covered (5.42 ± 0.63 vs. 5.88 ± 0.64 km; 88:10:2%; and η2 = 0.6) and low-intensity activity distance (4.21 ± 0.51 vs. 4.56 ± 0.57 km; 83:14:3%; and η2 = 0.6) compared with the control. A similar likely increase was also observed in the average TOI of the WBCG condition (53.5 ± 8.3% vs. 55.8 ± 7.2%; 87:11:2%; and η2 = 0.6). The current data demonstrated that wearing WBCGs likely increased physical performance, possibly because of improvements in muscle oxygenation and associated metabolic benefits. Therefore, wearing WBCGs during PHIIE may benefit the physical performance of team-sport athletes by likely metabolic changes within the muscle between high-intensity efforts.

Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion

The purpose of this study was to compare the effects of a cooling strategy designed to predominately lower thermal state with a strategy designed to lower thermal sensation on endurance running performance and physiology in the heat. Eleven moderately trained male runners completed familiarization and three randomized, crossover 5‐km running time trials on a non‐motorized treadmill in hot conditions (33 °C). The trials included ice slurry ingestion before exercise (ICE), menthol mouth rinse during exercise (MEN), and no intervention (CON). Running performance was significantly improved with MEN (25.3 ± 3.5 min; P = 0.01), but not ICE (26.3 ± 3.2 min; P = 0.45) when compared with CON (26.0 ± 3.4 min). Rectal temperature was significantly decreased with ICE (by 0.3 ± 0.2 °C; P < 0.01), which persisted for 2 km of the run and MEN significantly decreased perceived thermal sensation (between 4 and 5 km) and ventilation (between 1 and 2 km) during the time trial. End‐exercise blood prolactin concentration was elevated with MEN compared with CON (by 25.1 ± 24.4 ng/mL; P = 0.02). The data demonstrate that a change in the perception of thermal sensation during exercise from menthol mouth rinse was associated with improved endurance running performance in the heat. Ice slurry ingestion reduced core temperature but did not decrease thermal sensation during exercise or improve running performance.

The Construct and Longitudinal Validity of the Basketball Exercise Simulation Test

Scanlan, AT, Dascombe, BJ, and Reaburn, PRJ. The construct and longitudinal validity of the Basketball Exercise Simulation Test. J Strength Cond Res 26(2): 523–530, 2012—The purpose of this study was to assess the validity of the recently developed Basketball Exercise Simulation Test (BEST). Ten semiprofessional (age, 22.7 ± 6.1 years; height, 189.6 ± 9.5 cm; weight, 86.5 ± 18.7 kg; % body fat, 14.7 ± 3.5%) and 10 recreational (age, 26.6 ± 4.0 years; height, 185.9 ± 7.9 cm; weight, 92.6 ± 8.4 kg; % body fat, 23.8 ± 6.3%) male basketball players volunteered for the study. The participants completed a Yo-Yo Intermittent Recovery Test (Yo-Yo IRT) and BEST trial midway through the playing season. Eight participants (semiprofessional, n = 4; recreational, n = 4) completed an additional Yo-Yo IRT and BEST trial at the end of the playing season. Performance measures from the BEST included sprint decrement (%), mean sprint and circuit time (seconds), and total distance covered (m). Construct validity was calculated using Students unpaired t-tests to identify the differences in Yo-Yo IRT and BEST performances between playing levels. Longitudinal validity was determined based on the relationship between changes (%) in Yo-Yo IRT1 and BEST performances across the season. Semiprofessional players performed significantly (p < 0.01) better in the Yo-Yo IRT (1,283 ± 62 vs. 636 ± 297 m) and BEST (mean sprint time: 1.45 ± 0.01 vs. 1.65 ± 0.03 seconds; mean circuit time: 18.98 ± 1.79 vs. 22.72 ± 2.01 seconds; sprint decrement: 8.54 ± 0.15 vs. 15.38 ± 0.27%) compared with recreational players. For the group as a whole, a strong relationship was evident between the changes in BEST sprint decrement and changes in Yo-Yo IRT performance (R = −0.815, p = 0.014) across the season. In conclusion, the BEST displayed both discriminative and longitudinal validities and provides a novel match-specific fitness test for basketball players.

Contributing Factors to Change-of-Direction Ability in Professional Rugby League Players.

Abstract Delaney, JA, Scott, TJ, Ballard, DA, Duthie, GM, Hickmans, JA, Lockie, RG, and Dascombe, BJ. Contributing factors to change-of-direction ability in professional rugby league players. J Strength Cond Res 29(10): 2688–2696, 2015—Rugby league is an intermittent team sport in which players are regularly required to accelerate, decelerate, and change direction rapidly. This study aimed to determine the contributing factors to change-of-direction (COD) ability in professional rugby league players and to validate the physical and physiological components of a previously proposed COD ability predictor model. Thirty-one male professional rugby league players (age: 24.3 ± 4.4 years; height: 1.83 ± 0.06 m; body mass: 98.1 ± 9.8 kg) were assessed for anthropometry, linear speed, various leg muscle qualities, and COD ability. Change-of-direction ability was assessed for both the dominant (D) and nondominant (ND) legs using the 505 test. Stepwise multiple regression analyses determined the combined effect of the physical and physiological variables on COD ability. Maximal linear speed (SpMax) and relative squat strength (squat:BM) explained 61% of the variance in 505-D performance, whereas measures of mass, unilateral, and bilateral power contributed 67% to 505-ND performance. These results suggest that the 505-ND task was heavily dependent on relative strength and power, whereas the 505-D task was best predicted by linear sprint speed. Second, the physical component of the COD predictor model demonstrated poor correlations (r = −0.1 to −0.5) between absolute strength and power measures and COD ability. When made relative to body mass, strength and power measures and COD ability shared stronger relationships (r = −0.3 to −0.7). Change-of-direction ability in professional rugby league players would be best improved through increases in an athletes strength and power while maintaining lean muscle mass.

Physical performance during high-intensity resistance exercise in normoxic and hypoxic conditions

Abstract Scott, BR, Slattery, KM, Sculley, DV, Hodson, JA, and Dascombe, BJ. Physical performance during high-intensity resistance exercise in normoxic and hypoxic conditions. J Strength Cond Res 29(3): 807–815, 2015—This study aimed to determine whether different levels of hypoxia affect physical performance during high-intensity resistance exercise or subsequent cardiovascular and perceptual responses. Twelve resistance-trained young men (age, 25.3 ± 4.3 years; height, 179.0 ± 4.5 cm; body mass, 83.4 ± 9.1 kg) were tested for 1 repetition maximum (1RM) in the back squat and deadlift. Following this, participants completed 3 separate randomized trials of 5 × 5 repetitions at 80% 1RM, with 3 minutes rest between sets, in normoxia (NORM; fraction of inspired oxygen [FIO2] = 0.21), moderate-level hypoxia (FIO2 = 0.16), or high-level hypoxia (FIO2 = 0.13) by a portable hypoxic unit. Peak and mean force and power variables were monitored during exercise. Arterial oxygen saturation (SpO2), heart rate (HR), and rating of perceived exertion (RPE) were assessed immediately following each set. No differences in force or power variables were evident between conditions. Similar trends were evident in these variables across each set and across the exercise session in each condition. SpO2 was lower in hypoxic conditions than in NORM, whereas HR was higher following sets performed in hypoxia. There were no differences between conditions in RPE. These results indicate that a hypoxic stimulus during high-intensity resistance exercise does not alter physical performance during repetitions and sets or affect how strenuous exercise is perceived to be. This novel training strategy can be used without adversely affecting the physical training dose experienced and may provide benefits over the equivalent training in NORM.

Reliability and Usefulness of the 30-15 Intermittent Fitness Test in Rugby League

Abstract Scott, TJ, Delaney, JA, Duthie, GM, Sanctuary, CE, Ballard, DA, Hickmans, JA, and Dascombe, BJ. Reliability and usefulness of the 30-15 Intermittent Fitness Test in rugby league. J Strength Cond Res 29(7): 1985–1990, 2015—This study examined the reliability and usefulness of the 30-15 Intermittent Fitness Test (30-15IFT) within rugby league. Fifty-five young rugby league players participated in the study. These included representative players from Under 16s (n = 19; 15.6 ± 0.3 years; 78.1 ± 10.9 kg), Under 18s (n = 21; 17.4 ± 0.5 years; 86.9 ± 11.2 kg), and Under 20s (n = 15; 19.4 ± 0.5 years; 95.9 ± 8.7 kg) squads within a professional rugby league club. Players performed the 30-15IFT twice within 9 days of each other. Maximal intermittent running velocity (VIFT) and heart rate at exhaustion (HRpeak) were collected for both tests. Intraclass correlation coefficients (ICCs) for the “Combined” and Under 20s were very large (r > 0.7), whereas the ICCs for Under 16s and Under 18s were almost perfect (r > 0.9). Coefficients of variation were 1.9% (95% confidence interval, 1.6–2.4) for the combined test-retest of the 30-15IFT and 0.6% (0.5–1.0) for HRpeak. As the typical error of measurement (TE) (0.36 km·h−1) was greater than the smallest worthwhile change (SWC) (0.21 km·h−1) value, the usefulness of the VIFT was rated as “marginal.” The TE for HRpeak was similar to the SWC, rating the usefulness of this variable as “OK.” Despite the usefulness of the 30-15IFT being deemed Marginal, a change as small as 0.5 km·h−1 (1 stage) in VIFT could be considered substantial or “real.” As a consequence, the 30-15IFT presents as both a reliable and useful field test in the assessment of intermittent fitness for rugby league players.

Physical and Decision-Making Demands of Australian Football Umpires During Competitive Matches

Abstract Elsworthy, N, Burke, D, Scott, BR, Stevens, CJ, and Dascombe, BJ. Physical and decision-making demands of Australian football umpires during competitive matches. J Strength Cond Res 28(12): 3502–3507, 2014—This study examined the physical and decision-making requirements of elite Australian football (AF) umpires during match play. Twenty-nine field umpires were assessed across 20 AF League matches. Physical demands were monitored using global positioning system devices to record the total distance covered and high-speed running (HSR; >14.4 km·h−1) demands across each quarter. Decision-making performance was assessed through video by 3 elite umpire coaches who reviewed free-kick accuracy during each match. These data were further analyzed according to the position (mid-zone or end-zone) of the umpire when each decision was made. The average distance covered was 10,563 ± 608 m, of which 1,952 ± 494 m was HSR. Significant reductions in distance covered were observed during the third (p = 0.006) and fourth (p = 0.001) quarters, compared with the first. An average of 44 ± 8 free kicks awarded per match with a decision accuracy of 84 ± 6%; however, there were no significant differences (p > 0.05) in these measures across a match. Significantly (p ⩽ 0.05) higher physical (HSR; relative distance) and decision-making requirements were observed within the mid-zone. The current data quantify the physical and decision-making demands of AF umpiring and demonstrated that despite a high physical workload, free-kick accuracy is maintained across a match. This suggests that decision making may not be directly compromised by the intermittent running demands of AF umpires. Positional rotations between the mid-zone and end-zone position allow for the demands to be shared among all field umpires during a match.