Supramaximal Interval Running Prescription in Australian Rules Football Players: A Comparison Between Maximal Aerobic Speed, Anaerobic Speed Reserve, and the 30-15 Intermittent Fitness Test.

ABSTRACT: Collison, J, Debenedictis, T, Fuller, JT, Gerschwitz, R, Ling, T, Gotch, L, Bishop, B, Sibley, L, Russell, J, Hobbs, A, and Bellenger, CR. Supramaximal interval running prescription in Australian Rules Football players: A comparison between maximal aerobic speed, anaerobic speed reserve and the 30-15 intermittent fitness test. J Strength Cond Res 36(12): 3409-3414, 2022-Accurate prescription of supramaximal interval running during Australian Rules Football (AF) preparatory periods is important to facilitate the specific targeting of physiological and neuromuscular adaptation. This study compared the variability in supramaximal interval running performance prescribed by proportion of maximal aerobic speed (MAS), anaerobic speed reserve (ASR), and 30-15 intermittent fitness test (30-15IFT) terminal speed. Seventeen male junior AF players first completed assessments of MAS, ASR, and 30-15IFT in a randomized order. They subsequently performed supramaximal interval running trials (15 seconds on: 15 seconds off until volitional exhaustion) at 120% MAS, 20% ASR, and 95% 30-15IFT in a randomized order. Variability in time to exhaustion (TTE) for each prescription method was calculated as the mean of the square root of the squared difference between the individual value and the mean value, and it was compared via repeated-measures analysis of variance with statistical significance set at p ≤ 0.05. Time to exhaustion during supramaximal interval running was not different between the prescription methods ( p = 0.58). Time to exhaustion residuals were reduced when prescribed by ASR compared with MAS (standardized mean difference [SMD] = -0.47; 29%); however, confidence intervals about this reduction indicated that there was some uncertainty in this finding (SMD = -1.03 to 0.09; p = 0.09). Trivial differences in TTE residuals were present when prescribed by 30-15IFT compared with MAS (SMD = -0.05 ± 0.59; p = 0.86). Although there was some uncertainty about the reduction in supramaximal interval running performance variability when prescribed by ASR compared with MAS, the 29% reduction exceeds the inherent error in TTE efforts (i.e., ∼9-15%) and may thus be considered practically meaningful. Reducing supramaximal interval running performance variability ensures similar physiological demand across individuals, potentially facilitating similar degrees of physiological adaptation.

Muscle Fatigability After Hex-Bar Deadlift Exercise Performed With Fast or Slow Tempo.

PURPOSE: To examine the differences in muscle fatigability after resistance exercise performed with fast tempo (FT) compared with slow tempo (ST). METHODS: A total of 8 resistance-trained males completed FT and ST hexagonal-barbell deadlifts, consisting of 8 sets of 6 repetitions at 60% 3-repetition maximum, using a randomized crossover design. Each FT repetition was performed with maximal velocity, while each repetition during ST was performed with a 3-1-3 (eccentric/isometric/concentric) tempo (measured in seconds). Isometric maximal voluntary contraction, voluntary muscle activation, and evoked potentiated twitch torque of the knee extensors were determined using twitch interpolation before, during (set 4), and after exercise. Displacement-time data were measured during the protocols. RESULTS: The mean bar velocity and total concentric work were higher for FT compared with ST (995 [166] W vs 233 [52] W; 0.87 [0.05] m/s vs 0.19 [0.05] m/s; 4.8 [0.8] kJ vs 3.7 [1.1] kJ). Maximal voluntary contraction torque, potentiated twitch, and voluntary muscle activation were significantly reduced after FT (-7.8% [9.2%]; -5.2% [9.2%], -8.7% [12.2%]) and ST (-11.2% [8.4%], -13.3% [8.1%], -1.8% [3.6%]). CONCLUSION: The decline in maximal voluntary force after both the FT and ST hexagonal-barbell deadlifts exercise was accompanied by a similar decline in contractile force and voluntary muscle activation.

Performance comparison of the MOXY and PortaMon near-infrared spectroscopy muscle oximeters at rest and during exercise.

The purpose of the study was to compare muscle oxygenation as measured by two portable, wireless near-infrared spectroscopy (NIRS) devices under resting and dynamic conditions. A recently developed low-cost NIRS device (MOXY) was compared against an established PortaMon system that makes use of the spatially resolved spectroscopy algorithm. The influence of increasing external pressure on tissue oxygen saturation index (TSI) indicated that both devices are stable between 2 and 20 mmHg. However, above this pressure, MOXY reports declining TSI values. Analysis of adipose tissue thickness (ATT) and TSI shows a significant, nonlinear difference between devices at rest. The devices report similar TSI (%) values at a low ATT (<7 mm) (PortaMon minus MOXY difference is +1.1±2.8%) with the major subsequent change between the devices occurring between 7 and 10 mm; at ATT values >10 mm the difference remains constant (-14.7±2.8%). The most likely explanation for this difference is the small source-detector separation (2.5 cm) in the MOXY resulting in lower tissue penetration into muscle in subjects with higher ATT. Interday test-retest reliability of resting TSI was evaluated on five separate occasions, with the PortaMon reporting a lower coefficient of variation (1.8% to 2.5% versus 5.7% to 6.2%). In studies on male subjects with low ATT, decreases in the TSI were strongly correlated during isometric exercise, arterial occlusion, and incremental arm crank exercise. However, the MOXY reports a greater dynamic range, particularly during ischemia induced by isometric contraction or occlusion (Δ74.3% versus Δ43.7%; hyperemia MAX-occlusion MIN). This study shows that in this subject group both MOXY and PortaMon produce physiologically credible TSI measures during rest and exercise. However, the absolute values obtained during exercise are generally not comparable between devices unless corrected by physiological calibration following an arterial occlusion.

Maturation-related adaptations in running speed in response to sprint training in youth soccer players.

OBJECTIVES: This study investigated the effects of a previously recommended dose of sprint training (ST) in young male soccer players of differing maturity status. DESIGN: Quasi-experimental design. METHODS: Male soccer players from two professional academies were divided into Pre-PHV (Training: n=12; Control: n=13) and Mid-PHV (Training: n=7; Control=10) groups. The training groups completed 16 sprints of 20m with 90s recovery, once per week for 8weeks. RESULTS: Between-group effect sizes (ES) were substantially larger in Pre-PHV (10m [1.54, CI: 0.74-2.23]; 20m [1.49, CI: 0.75-2.23]; 5-10-5 [0.92, CI: 0.23-1.61]) than in Mid-PHV (10m [-0.00, CI: -0.81 to 0.81]; 20m [-0.12, CI: -0.93 to 0.69]; 5-10-5 [-0.41, CI: -1.22 to 0.41]). Within-group effects demonstrated a similar, though less accentuated, trend which revealed ST to be effective in both Pre-PHV (10m [0.44, CI: -0.24 to 1.12]; 20m [0.45, CI: -0.23 to 1.13]; 5-10-5 [0.69, CI: 0.00-1.38]) and Mid-PHV (10m [0.51, CI: -0.38 to 1.40]; 20m [0.33, CI: -0.56 to 1.21]; 5-10-5 [0.43, CI: -0.46 to 1.32]). CONCLUSIONS: ST, in the amount of 16 sprints over 20m with a 90s rest, may be more effective in Pre-PHV youths than in Mid-PHV youths.

Age-Related Variation in Male Youth Athletes' Countermovement Jump After Plyometric Training: A Meta-Analysis of Controlled Trials.

Moran, J, Sandercock, GRH, Ramírez-Campillo, R, Meylan, CMP, Collison, J, and Parry, DA. Age-related variation in male youth athletes' countermovement jump after plyometric training: A meta-analysis of controlled trials. J Strength Cond Res 31(2): 552-565, 2017-Recent debate on the trainability of youths has focused on the existence of periods of accelerated adaptation to training. Accordingly, the purpose of this meta-analysis was to identify the age- and maturation-related pattern of adaptive responses to plyometric training in youth athletes. Thirty effect sizes were calculated from the data of 21 sources with studies qualifying based on the following criteria: (a) healthy male athletes who were engaged in organized sport; (b) groups of participants with a mean age between 10 and 18 years; and (c) plyometric-training intervention duration between 4 and 16 weeks. Standardized mean differences showed plyometric training to be moderately effective in increasing countermovement jump (CMJ) height (Effect size = 0.73 95% confidence interval: 0.47-0.99) across PRE-, MID-, and POST-peak height velocity groups. Adaptive responses were of greater magnitude between the mean ages of 10 and 12.99 years (PRE) (ES = 0.91 95% confidence interval: 0.47-1.36) and 16 and 18 years (POST) (ES = 1.02 [0.52-1.53]). The magnitude of adaptation to plyometric training between the mean ages of 13 and 15.99 years (MID) was lower (ES = 0.47 [0.16-0.77]), despite greater training exposure. Power performance as measured by CMJ may be mediated by biological maturation. Coaches could manipulate training volume and modality during periods of lowered response to maximize performance.

Maturation-Related Effect of Low-Dose Plyometric Training on Performance in Youth Hockey Players.

PURPOSE: The purpose of this intervention study was to investigate if a low-dose of plyometric training (PT) could improve sprint and jump performance in groups of different maturity status. METHOD: Male youth field hockey players were divided into Pre-PHV (from -1 to -1.9 from PHV; Experimental: n = 9; Control = 12) and Mid-PHV (0 to +0.9 from PHV; Experimental: n = 8; Control = 9) groups. Participants in the experimental groups completed 60 foot contacts, twice-weekly for 6 weeks. RESULTS: PT exerted a positive effect (effect size: 0.4 [-0.4-1.2]) on 10 m sprint time in the experimental Mid-PHV group but this was less pronounced in the Pre-PHV group (0.1 [-0.6-0.9]). Sprint time over 30 m (Mid-PHV: 0.1 [-0.8-0.9]; Pre-PHV: 0.1 [-0.7-0.9]) and CMJ (Mid-PHV: 0.1 [-0.8-0.9]; Pre-PHV: 0.0 [-0.7-0.8]) was maintained across both experimental groups. Conversely, the control groups showed decreased performance in most tests at follow up. Between-group analysis showed positive effect sizes across all performance tests in the Mid-PHV group, contrasting with all negative effect sizes in the Pre-PHV group. CONCLUSION: These results indicate that more mature hockey players may benefit to a greater extent than less mature hockey players from a low-dose PT stimulus. Sixty foot contacts, twice per week, seems effective in improving short sprint performance in Mid-PHV hockey players.

A meta-analysis of maturation-related variation in adolescent boy athletes' adaptations to short-term resistance training.

This meta-analysis investigated the maturation-related pattern of adaptations to resistance training in boy athletes. We included studies examining the effects of 4-16-week resistance training programmes in healthy boy athletes aged 10-18 years. Pooled estimates of effect size for change in strength across all studies (n = 19) were calculated using the inverse-variance random effects model for meta-analyses. Estimates were also calculated for groups based on likely biological maturity status ("before", "during" and "after" peak height velocity). Using the standardised mean difference, resistance training increased strength across all groups (effect size = 0.98, [CI: 0.70-1.27]). Strength gains were larger during (1.11 [0.67-1.54]) and after (1.01 [0.56-1.46]) peak height velocity than before (0.5 [-0.06-1.07]). Adaptations to resistance training are greater in adolescent boys during or after peak height velocity. These findings should help coaches to optimise the timing of training programmes that are designed to improve strength in boy athletes.