Effects of a 12-Week Training Program on Isometric and Dynamic Force-Time Characteristics in Pre- and Post-Peak Height Velocity Male Athletes

Effects of Neuromuscular Training on Muscle Architecture, Isometric Force Production, and Stretch-Shortening Cycle Function in Trained Young Female Gymnasts

ABSTRACT

Moeskops, S, Oliver, JL, Radnor, JM, Haff, GG, Myer, GD, Ramachandran, AK, Kember, LS, Pedley, JS, and Lloyd, RS. Effects of neuromuscular training on muscle architecture, isometric force production, and stretch-shortening cycle function in trained young female gymnasts. J Strength Cond Res XX(X): 000-000, 2024-This study evaluated the effects of a 10-month neuromuscular training (NMT) intervention on muscle architecture, isometric force production, and stretch-shortening cycle (SSC) function. Thirty-seven girls aged 6-12 years were placed into gymnastics + NMT (gNMT; n = 15), gymnastics only (GYM; n = 10), or maturity-matched control (CON; n = 12) groups. The gNMT group followed a 10-month NMT program in addition to gymnastics training, whereas the GYM group only participated in gymnastics training. Isometric midthigh pull (IMTP) and drop jump (DJ) kinetics were measured, in addition to muscle thickness, fascicle length, and pennation angle of the gastrocnemius medialis at baseline and at 4, 7, and 10 months. A 3 × 4 (group × time) repeated-measures ANCOVA (covariate, % predicted adult height) was used to evaluate within-group changes. Significance level was set at p < 0.05. Significant interaction effects were observed in muscle thickness, absolute (PFabs) and relative peak force (PFrel) in the IMTP and various DJ variables. The gNMT group demonstrated improvements in muscle thickness, IMTP PFabs and PFrel, and DJ kinetics, most commonly evidenced from 7 months onward. The GYM group's muscle thickness also significantly improved, accompanied by improvements in some DJ kinetics. The CON group did not experience any desirable changes. Overall, NMT elicited positive changes in muscle thickness, PFabs and PFrel, and SSC function to a greater extent than gymnastics training alone or growth and maturation. As most adaptations took 7 months, longer-term NMT programs should be implemented with youth female gymnasts.

Twelve Weeks of Progressive Resistance Training Positively Improves Physical Fitness and Golf Swing Performance in Talented Youth Golfers

ABSTRACT

Shaw, J, Gould, ZI, Oliver, JL, and Lloyd, RS. Twelve weeks of progressive resistance training positively improves physical fitness and golf swing performance in talented youth golfers. J Strength Cond Res 38(6): 1103-1110, 2024-This aim of this study was to investigate the effects of a 12-week resistance training program in talented junior golfers. Eighteen talented youth golfers were pair matched by maturity status and handicap, and subsequently allocated to an experimental (EXP) or control group. During the 12-week intervention, both groups continued with their normal golf practice while the EXP group also completed a progressive twice-weekly resistance training program. At baseline, subjects performed multiple trials of an isometric midthigh pull (IMTP), countermovement jump (CMJ), standing long jump, golf movement screen (GMS), and isometric plank hold. Club head speed (CHS) and carry distance for a 6-iron and driver were also measured using a commercial launch monitor. When controlled for maturity offset, there were significant ( p < 0.05) interaction effects in favor of the EXP group for absolute ( g = 1.29) and relative ( g = 2.06) peak force for the IMTP, CMJ absolute ( g = 0.73) and relative ( g = 0.66) peak power, jump height ( g = 1.05), modified reactive strength index ( g = 1.30), lateral ( g = 0.48-0.88) and horizontal jump distance ( g = 1.20), and GMS total score ( g = 1.07). Significant interaction effects were also reported in 6-iron and driver CHS and carry distance in favor of the EXP group ( p < 0.05; g = 0.41-1.64). These findings indicate that twice-weekly resistance training in combination with regular golf practice can stimulate increases in measures of strength, power, and movement competency in youth golfers, which should contribute to enhanced golf swing performance.

Physical determinants of golf swing performance in competitive youth golfers

This study investigated measures of physical fitness and golf swing performance in competitive youth golfers. Sixty-four golfers, subdivided into three handicap groups (CAT0, <1 handicap, n = 21; CAT1, 1-5 handicap, n = 20; CAT2, >5 handicap, n = 23), were assessed for isometric strength, power, movement competency and core endurance. Clubhead speed (CHS) and carry distance for 6-iron and driver were also measured. When controlled for maturity offset, CAT0 golfers produced significantly greater peak power, isometric absolute and relative peak force, movement competency, and jump distance than higher handicap golfers (all p < 0.05). Maturity status was strongly associated with CHS and carry distance for both clubs (R2 = 0.552-0.784). Linear regressions showed maturity offset explained a larger amount of variance in CHS (driver = 78.4%, 6-iron = 71.3%) and carry distance (driver = 55.2%, 6-iron = 57.4%) than handicap. Multiple linear regression analyses showed that peak power explained 79.4% and 82.4% of variation in 6-iron and driver CHS, respectively, while isometric absolute peak force explained 69.6% and 74.3% of the variation in 6-iron and driver carry distance, respectively. Subsequently, interventions targeting the development of peak force and power could aid golf swing performance in young golfers.

Kinetic Responses to External Cues Are Specific to Both the Type of Cue and Type of Exercise in Adolescent Athletes

ABSTRACT

Barillas, SR, Oliver, JL, Lloyd, RS, and Pedley, J. Kinetic responses to external cues are specific to both the type of cue and type of exercise in adolescent athletes. J Strength Cond Res 37(3): 597-605, 2023-The purpose of this study was to examine how external cues influence kinetics during isometric and dynamic tasks in adolescent athletes. Fifteen adolescent male soccer players performed an isometric midthigh pull (IMTP), unloaded and loaded squat jumps (SJs) (15 and 30% of body mass), countermovement jump (CMJ), and drop jump (DJ) using a neutral or external force-specific or velocity-specific cues. Cue type had limited effects on outcomes in the IMTP or SJs, with mostly trivial ( g < 0.20), nonsignificant differences ( p > 0.05) across kinetic variables. In the CMJ and DJ, a force cue significantly ( p < 0.05) increased jump height ( g = 0.43 & 0.52) compared with a velocity cue, but in the DJ, a force cue significantly increased jump height ( g = 0.52) compared with both a neutral and velocity cue. However, a velocity cue significantly ( p < 0.05) reduced ground contact time ( g = 0.73-1.52) and time to peak force ( g = 0.50-1.29) in both the CMJ and DJ when compared with a force and neutral cue and increased force and power-related measures ( g = 0.33-1.12) in the CMJ and DJ when compared with a force cue. In adolescent athletes, the type of external cue had limited effects on kinetic measures in an IMTP and SJ but differential effects on both a CMJ and DJ, suggesting cues have more effect with increasing movement velocity. Consequently, practitioners working with adolescent athletes should consider both the type of exercise and the desired outcome when providing external cues.

Strength and VO2max Changes by Exercise Training According to Maturation State in Children

The health benefits of physical activity (PA) are widely recognized; however, biological maturation contributions are a subject that has been little studied, which is why the aim of this study was to analyze the effect of a six-week training program at moderate-intensity on the muscular strength and aerobic capacity in children between nine and 13 years (13 ± 1.0 years) according to their maturation state. Twenty-six schoolchildren (15 girls) participated in a six-week physical exercise program based on aerobic/anaerobic capacity and coordination skills. Maximal oxygen uptake (VO2max), trunk-lift, push-ups, curl-ups, and handgrip strength (both hands) were measured as response variables. Body mass index (BMI), skeletal maturity indicator (SMI), peak height velocity (PHV), age on peak height velocity (APHV) and sex were considered as covariates. The results of VO2max, push-ups, curl-ups, and handgrip strength were higher after the exercise program in the whole group (p < 0.05). The VO2max showed a greater increase in the normal-weight than in the overweight-obesity children (p = 0.001). Higher results in dominant handgrip strength were observed in girls (p = 0.003). The PHV before intervention presented a positive correlation with the dominant handgrip strength in all kids (r = 0.70, p = 0.001). As a conclusion, the six-week training program improved the physical fitness of children independent of the maturation state. Somatic maturation increases the physical abilities in schoolchildren.

How to Improve the Reactive Strength Index among Male Athletes? A Systematic Review with Meta-Analysis

The reactive strength index (RSI) describes the individual’s capability to quickly change from an eccentric muscular contraction to a concentric one and can be used to monitor, assess, and reduce the risk of athlete’s injury. The purpose of this review is to compare the effectiveness of different training programs on RSI. Electronic searches were conducted in MEDLINE, PubMed, Scopus, SPORTDiscus, and Web of Science from database inception to 11 February 2022. This meta-analysis was conducted in accordance with the recommendations of the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The search returned 5890 records, in which 39 studies were included in the systematic review and 30 studies were included in the meta-analysis. Results from the randomized studies with the control group revealed that plyometric training improved RSI in adult athletes (0.84, 95% CI 0.37 to 1.32) and youth athletes (0.30, 95% CI 0.13 to 0.47). Evidence withdrawn from randomized studies without a control group revealed that resistance training also improved the RSI (0.44, 95% CI 0.08 to 0.79) in youth athletes but not in adults. Interventions with plyometric training routines have a relatively large, statistically significant overall effect in both adult and youth athletes. This supports the implementation of this type of interventions in early ages to better cope with the physical demands of the various sports. The impact of resistance training is very low in adult athletes, as these should seek to have a more power-type training to see improvements on the RSI. More interventions with sprint and combined training are needed.

Effects of Training Frequency During a 6-Month Neuromuscular Training Intervention on Movement Competency, Strength and Power in Male Youth

Background:

Youth populations benefit from neuromuscular training; however, the extent to which training frequency, baseline fitness, and maturity status moderate the response to long-term neuromuscular training in male youth remains unclear.

Hypothesis:

Twice-weekly training (G2x) would induce larger improvements in movement competency and strength and power kinetics compared with once-weekly training (G1x). Maturity status and baseline fitness would also moderate the training response in strength and power kinetics.

Study Design:

Nonrandomized, repeated-measures design.

Level of Evidence:

Level 3

Methods:

Ninety-five male athletes of varying maturity status (pre– or post–peak height velocity) were divided into G2x, G1x, or control (CON) groups. Training groups received G2x or G1x for 28 weeks. Back squat assessment (BSA) movement competency and isometric mid-thigh pull (IMTP), squat jump (SJ), and countermovement jump (CMJ) kinetics were measured pre- and postintervention.

Results:

The G2x achieved significantly greater adaptations in BSA total score, IMTP allometrically scaled peak force (PF_allo), IMTP peak rate-of-force development (PRFD), SJ PF_allo and PRFD compared with G1x and CON (P < 0.05; d = 0.3-0.9). Baseline fitness, training frequency and maturity status were significant predictors of IMTP PF_allo (R² = 27.5%) and PRFD (R² = 42.9%), while a combination of training frequency and baseline fitness explained a small amount of variance in SJ PF_allo (R² = 12.2%) and SJ PRFD (R² = 6.5%). There were no significant predictors of CMJ kinetics.

Conclusion:

G2x achieved significantly larger improvements in movement competency, isometric strength and concentric jump variables compared with G1x, with the training response greater in those youth with lower baseline fitness and more advanced maturity status.

Clinical Relevance:

Exposure to neuromuscular training twice-weekly elicits a greater response than G1x in young male athletes. Practitioners should take maturity status, training frequency, and baseline fitness levels of young male athletes into account when interpreting testing data, as these variables appear to moderate training responsiveness.