Reliability of Measures of Lower-Body Strength and Speed in Academy Male Adolescent Soccer Players.

ABSTRACT: Ferguson, J, Gibson, NV, Weston, M, and McCunn, R. Reliability of measures of lower body strength and speed in academy male adolescent soccer players. J Strength Cond Res 38(3): e96-e103, 2024-The Nordbord and ForceFrame represent a practical and time efficient means of assessing eccentric hamstring and isometric adductor strength in the large number of squads and players associated with youth soccer academies, yet measurement reliability in this population is unexamined. Therefore, over a period of 4 days, with no less than 24 hours and no more than 48 hours between trials, 37 players (age: 14.7 ± 0.8 years, stature: 168.7 ± 7.8 cm, mass: 57.7 ± 9.1 kg, and maturity offset: 0.8 ± 0.9 years) were assessed for eccentric hamstring strength (force, torque), isometric adductor strength (long and short lever positions), and 30-m sprint (5, 10, and 20-m splits), using the Nordbord, ForceFrame, and electronic timing gates, respectively, on 3 separate occasions. Relative reliability (intraclass correlation coefficient) was rated as good for all Nordbord (range: 0.86-0.89) and ForceFrame (0.78-0.85) measures and ranged from moderate (0.53) to excellent (0.93) for the speed measures, improving with increased distance. Absolute reliability (standard error of the measurement [%SEM]) ranged from 7 to 8% (Nordbord), 3 to 11% (ForceFrame), and 1 to 4% (sprints). Our data provide the first Nordbord and ForceFrame reliability estimates in adolescent soccer academy players. To interpret test sensitivity, practitioners are encouraged to interpret our estimates of absolute reliability against meaningful change values derived from personal experience and evidence-based knowledge and not against absolute or standardized thresholds.

Reliability and Validity of a 6-Minute Yo-Yo Intermittent Endurance Test Level 2 in Subelite Part Time Male Soccer Players.

ABSTRACT: Gibson, N, Easton, C, Williams, M, McCunn, R, Gibson, NV. Reliability and validity of a 6-minute Yo-Yo Intermittent Endurance Test Level 2 in subelite part time male soccer players. J Strength Cond Res 36(4): 1011-1018, 2022-The aim of this study was to assess the reliability and relationship to maximal intermittent running performance of the 6-minute Yo-Yo Intermittent Endurance Test Level 2 (YYIET2), among subelite part time soccer players. Twenty male soccer players (15-22 years) completed three 6-minute YYIET2 trials with heart rate (HR), PlayerLoad, and rating of perceived exertion assessed during the protocol and HR and blood lactate assessed during 5 minutes of recovery. Subjects also completed a maximal version of the YYIET2 and the maximal Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1) and 2 (YYIRT2). Heart rate at 4 and 6 minutes, PlayerLoad at 4 minutes, and HR recovery at 2, 3, 4, and 5 minutes during recovery from the 6-minute YYIET2 demonstrated little variance between tests. Correlations between variables measured during and after the 6-minute YYIET2 and distance covered in maximal tests ranged from r = 0.02 to -0.72. The 6-minute YYIET2 provides practitioners with a method of reliably assessing HR responses within subelite part time soccer players, although large correlations with maximal assessments suggest it can be used as a proxy measure for maximal intermittent running performance. Given its ease of administration and low time cost, the 6-minute YYIET2 offers practitioners a useful means of tracking training status and movement efficiency in players longitudinally.

Activation of the Gluteus Maximus During Performance of the Back Squat, Split Squat, and Barbell Hip Thrust and the Relationship With Maximal Sprinting.

ABSTRACT: Williams, MJ, Gibson, N, Sorbie, GG, Ugbolue, UC, Brouner, J, and Easton, C. Activation of the gluteus maximus during performance of the back squat, split squat, and barbell hip thrust and the relationship with maximal sprinting. J Strength Cond Res 35(1): 16-24, 2021-The purpose of this research was to compare muscle activation of the gluteus maximus and ground reaction force between the barbell hip thrust, back squat, and split squat and to determine the relationship between these outcomes and vertical and horizontal forces during maximal sprinting. Twelve, male, team sport athletes (age, 25.0 ± 4.0 years; stature, 184.1 ± 6.0 cm; body mass, 82.2 ± 7.9 kg) performed separate movements of the 3 strength exercises at a load equivalent to their individual 3 repetition maximum. The ground reaction force was measured using force plates and the electromyography (EMG) activity of the upper and lower gluteus maximus and was recorded in each leg and expressed as percentage of the maximum voluntary isometric contraction (MVIC). Subjects then completed a single sprint on a nonmotorized treadmill for the assessment of maximal velocity and horizontal and vertical forces. Although ground reaction force was lower, peak EMG activity in the gluteus maximus was higher in the hip thrust than in the back squat (p = 0.024; 95% confidence interval [CI] = 4-56% MVIC) and split squat (p = 0.016; 95% CI = 6-58% MVIC). Peak sprint velocity correlated with both anterior-posterior horizontal force (r = 0.72) and peak ground reaction force during the barbell hip thrust (r = 0.69) but no other variables. The increased activation of gluteus maximus during the barbell hip thrust and the relationship with maximal running speed suggests that this movement may be optimal for training this muscle group in comparison to the back squat and split squat.

The Effect of Maturation on Performance During Repeated Sprints With Self-Selected Versus Standardized Recovery Intervals in Youth Footballers.

PURPOSE: The purpose of this experiment was to assess performance during repeated sprints utilizing self-selected recovery intervals in youth football (soccer) players at different stages of maturation. METHODS: Quota sampling method was used to recruit 14 prepeak height velocity (PHV) and 14 post-PHV participants for the study (N = 28; age = 13 [0.9] y, stature = 162.5 [10.8] cm, mass = 50.2 [12.7] kg). Players performed repeated sprints comprising 10 × 30 m efforts under 2 experimental conditions: using 30-second and self-selected recovery intervals. Magnitude of effects for within- and between-group differences were reported using effect size (ES) statistics ± 90% confidence intervals and percentage differences. RESULTS: The decline in sprint performance was likely lower in the pre-PHV compared with the post-PHV group during the standardized recovery trial (between-group difference = 37%; ES = 0.41 ± 0.51), and likely lower in the post-PHV group during the self-selected recovery trial (between-group difference = 50%; ES = 0.45 ± 0.54). Mean recovery duration was likely shorter in the pre-PHV compared with the post-PHV group during the self-selected recovery trial (between-group difference = 26.1%; ES = 0.47 ± 0.45). CONCLUSION: This is the first study to show that during repeated sprints with self-selected recovery, pre-PHV children have an impaired ability to accurately interpret physical capabilities in the context of the task compared with post-PHV adolescents.

Interval running with self-selected recovery: Physiology, performance, and perception.

This study (1) compared the physiological responses and performance during a high-intensity interval training (HIIT) session incorporating externally regulated (ER) and self-selected (SS) recovery periods and (2) examined the psychophysiological cues underpinning SS recovery durations. Following an incremental maximal exercise test to determine maximal aerobic speed (MAS), 14 recreationally active males completed 2 HIIT sessions on a non-motorised treadmill. Participants performed 12 × 30 s running intervals at a target intensity of 105% MAS interspersed with 30 s (ER) or SS recovery periods. During SS, participants were instructed to provide themselves with sufficient recovery to complete all 12 efforts at the required intensity. A semi-structured interview was undertaken following the completion of SS. Mean recovery duration was longer during SS (51 ± 15 s) compared to ER (30 ± 0 s; p < .001; d = 1.46 ± 0.46). Between-interval heart rate recovery was higher (SS: 19 ± 9 b min-1; ER: 8 ± 5 b min-1; p < .001; d = 1.43 ± 0.43) and absolute time ≥90% maximal heart rate (HRmax) was lower (SS: 335 ± 193 s; ER: 433 ± 147 s; p = .075; d = 0.52 ± 0.39) during SS compared to ER. Relative time ≥105% MAS was greater during SS (90 ± 6%) compared to ER (74 ± 20%; p < .01; d = 0.87 ± 0.40). Different sources of afferent information underpinned decision-making during SS. The extended durations of recovery during SS resulted in a reduced time ≥90% HRmax but enhanced time ≥105% MAS, compared with ER exercise. Differences in the afferent cue utilisation of participants likely explain the large levels of inter-individual variability observed.

Match Demands of Senior and Junior Players During International Rugby League.

Dempsey, GM, Gibson, NV, Sykes, D, Pryjmachuk, BC, and Turner, AP. Match demands of senior and junior players during International Rugby League. J Strength Cond Res 32(6): 1678-1684, 2018-This study aims to quantify and compare the positional game demands of international junior and senior rugby league competition for the first time. Global positioning system (GPS) and video analysis were used to track 118 elite male rugby league players (57 seniors aged 28.7 ± 4.4 years; 61 juniors aged 17.2 ± 0.5 years) over 10 international matches (6 senior; 4 junior) characterized as either forwards (n = 67) or backs (n = 51). There were significant increases in the offensive carries (0.18 cf. 0.09 n·min; r = 0.56) and defensive tackles (0.36 cf. 0.23 n·min; r = 0.3) between senior and junior players, and forwards and backs (0.16 cf. 0.09; r = 0.34 and 0.41 cf. 0.14; r = 0.52), respectively. Running demands were significantly greater in backs than forwards (independent of playing level) for total distance (6,962 ± 1,263 m cf. 4,879 ± 1,824 m; r = 0.55), individualized high-speed distances (310 ± 158 m cf. 250 ± 171 m; r = 0.2), high-intensity accelerations (28.7 ± 12.1 m·s cf. 21.9 ± 11.7 m·s; r = 0.27), and decelerations (57.2 ± 18.3 m·s cf. 43.0 ± 17.8 m·s; r = 0.38). Positional differences were eliminated when reported relative to minutes played. From a practical perspective, although running demands relative to time on the pitch may prepare junior players for senior competition, it is not representative of the increased body mass and contact frequency within the senior game. Coaches should therefore reflect these differences within their physical preparation programs to prepare junior athletes accordingly for progression to the senior level.

Influence of Physical Maturity Status on Sprinting Speed Among Youth Soccer Players.

McCunn, R, Weston, M, Hill, JKA, Johnston, RD, and Gibson, NV. Influence of physical maturity status on sprinting speed among youth soccer players. J Strength Cond Res 31(7): 1795-1801, 2017-The relative age effect is well documented with the maturation-selection hypothesis the most common explanation; however, conflicting evidence exists. We observed the birth date distribution within an elite junior soccer academy. The influence of physical maturity status on anthropometric variables and sprinting ability was also investigated. Annual fitness testing was conducted over an 8-year period with a total of 306 players (age: 12.5 ± 1.7 years [range: 9.7-16.6 years]; stature: 156.9 ± 12.9 cm; mass: 46.5 ± 12.5 kg) drawn from 6 age categories (under-11s to under-17s) who attended the same Scottish Premiership club academy. Measurements included mass, stature, maturity offset and 0-15 m sprint. Odds ratios revealed a clear bias toward recruitment of players born in quartile 1 compared with quartile 4. The overall effect (all squads combined) of birth quartile was very likely small for maturity offset (0.85 years; 90% confidence interval [CI], 0.44-1.26 years) and stature (6.2 cm; 90% CI, 2.8-9.6 cm), and likely small for mass (5.1 kg; 90% CI, 1.7-8.4 kg). The magnitude of the relationship between maturity offset and 15-m sprinting speed ranged from trivial for under-11s (r = 0.01; 90% CI, -0.14 to 0.16) to very likely large for under-15s (r = -0.62; -0.71 to -0.51). Making decisions about which players to retain and release should not be based on sprinting ability around the under-14 and under-15 age categories because any interindividual differences may be confounded by transient inequalities in maturity offset.

Physiological responses to an intensified period of rugby league competition.

This study investigated the physiological responses to an intensified period of rugby league competition and the subsequent impact on match performance. The participants were 7 rugby league players competing in an international student tournament. The tournament involved three 80-minute games over a 5-day period, with 48 hours between each match. Baseline measures of upper and lower body neuromuscular functions via a plyometric press-up (PP) and countermovement jump (CMJ), respectively (peak power and peak force were measured), blood creatine kinase (CK), and perceptions of well-being were assessed with a questionnaire. These measures were repeated every morning of the competition; neuromuscular fatigue and CK were additionally assessed within 2 hours after the cessation of each game. During each match, player movements were recorded via global positioning system units. There were meaningful reductions in upper (effect size [ES] = -0.55) and lower body (ES = -0.73) neuromuscular functions, and perceptual well-being (ES = -1.56) and increases in blood CK (ES = 2.32) after game 1. These changes increased in magnitude as the competition progressed. There were large reductions in the relative distance covered in high-speed running (ES = -1.49) and maximal accelerations (ES = -0.85) during game 3. Additionally, moderate reductions in the percentage of successful tackles completed were observed during game 3 (ES = -0.59). Collectively, these results demonstrate that during an intensified period of rugby league competition, characterized by only 48 hours between matches, fatigue will accumulate. This cumulative fatigue may compromise high-intensity match activities such as high-speed running, accelerations, and tackling. Furthermore, CMJs and PPs appear to be sensitive measures for monitoring neuromuscular function in rugby league players.