Maturation-Related Differences in Adaptations to Resistance Training in Young Male Swimmers.

Moran, J, Sandercock, GRH, Ramírez-Campillo, R, Wooller, J-J, Logothetis, S, Schoenmakers, PPJM, and Parry, DA. Maturation-related differences in adaptations to resistance training in young male swimmers. J Strength Cond Res 32(1): 139-149, 2018-This study examined the effects of resistance training on muscular strength and jump performances in young male swimmers. It was hypothesized that adaptations would be of a lower magnitude in less mature (prepeak height velocity [PHV]) than in more mature (post-PHV) subjects. Fourteen pre-PHV (-1.8 ± 1.0 years) and 8 post-PHV (1.6 ± 0.5 years) swimmers undertook a 30 minutes, twice-weekly resistance training program for 8 weeks. They were compared with matched control groups (pre-PHV: -2.0 ± 1.1, n = 15; post-PHV: 1.2 ± 1.0, n = 7). The effects on lower-body isometric strength (LBS), measured with midthigh pull, and vertical jump (VJ) height in the post-PHV group were large (effect size: 1.3 [0.4 to 2.2]) and small (0.4 [-0.4 to 1.2]), respectively. Effects on LBS and VJ height in the pre-PHV group were moderate (0.8 [0.1 to 1.4]) and trivial (0.2 [-0.5 to 0.8]), respectively. Estimates in the post-PHV control group (LBS: 0.7 [-0.2 to 1.6]; VJ: 0.2 [-0.7 to 1.0]) and the pre-PHV control group (LBS: 0.1 [-0.5 to 0.7]; VJ: -0.3 [-0.9 to 0.3]) may indicate the extent to which maturation could contribute to the performance changes seen in the respective training groups. Lower-body isometric strength and VJ are trainable, but to different magnitudes, in pre- and post-PHV swimmers. After appropriate foundational training to establish technical competency, twice-weekly resistance training sessions of 30 minutes duration, comprising 3 sets of 4 exercises can be effective in pre- and post-PHV youth.

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.