Youth may be particularly responsive to motor learning training strategies that support injury-resistant movement mechanics in youth for prevention programs that reduce injury risk, injury rehabilitation, exercise performance, and play more generally (Optimizing Performance Through Intrinsic Motivation and Attention for Learning Prevention Rehabilitation Exercise Play; OPTIMAL PREP) One purpose of the present manuscript was to provide clinical applications and tangible examples of how to implement the proposed techniques derived from OPTIMAL theory into PREP strategies for youth. A secondary purpose was to review recent advances in technology that support the clinical application of OPTIMAL PREP strategies without extensive resources/programming knowledge to promote evidence-driven tools that will support practitioner feedback delivery. The majority of examples provided are within the context of anterior cruciate ligament (ACL) injury rehabilitation, but we emphasize the potential for OPTIMAL PREP strategies to be applied to a range of populations and training scenarios that will promote injury resistance and keep youth active and healthy.
Youth athletes are ideal candidates for novel therapeutic motor learning interventions that leverage the plasticity of the central nervous system to promote desirable biomechanical adaptions. We summarize the empirical data supporting the three pillars of the Optimizing Performance Through Intrinsic Motivation and Attention for Learning (OPTIMAL) theory of motor learning and expand on potential neurophysiologic mechanisms that will support enhanced movement mechanics in youth to optimize prevention programs for reduced injury risk, injury rehabilitation, exercise performance, and play (Prevention Rehabilitation Exercise Play; PREP). Specifically, we highlight the role of motivational factors to promote the release of dopamine that could accelerate motor performance and learning adaptations. Further, we detail the potential for an external focus of attention to shift attentional allocation and increase brain activity in regions important for sensorimotor integration to facilitate primary motor cortex efficiency. This manuscript serves to provide the most current data in support of the application of OPTIMAL PREP training strategies of the future.
Neuromuscular training aims to enhance motor skill competency and increase muscle strength. However, the effectiveness of short-duration interventions focused on addressing lower limb injury risk factors in male youth athletes at different stages of maturity remains unknown.
Forty-eight young male academy cricket players [pre-peak height velocity (PHV) (n = 26) and post-PHV (n = 22)] were subdivided into an experimental group (EXP) who completed a 4-week progressive neuromuscular training program and controls (CON) participating in sport training only. Changes in injury risk were examined using the Tuck Jump Assessment (TJA) and Landing Error Scoring System (LESS).
Total LESS score was significantly lower in both EXP maturity groups compared to CON following the 4-week program (10 to 6 and 6 to 4 (~ 20% to 40%)) in the pre- and post-PHV EXP groups, respectively. Significant within-group reductions in total LESS score were shown for the pre-PHV EXP group only (P < 0.05). Conversely, greater changes in TJA total score were shown in post-PHV (5 to 3; 40%) versus pre-PHV EXP (6 to 4.5; 26%). Pre-PHV players showed positive changes in individual LESS criteria indicative of frontal plane control but not in knee valgus during the TJA, whereas post-PHV players did improve this criterion.
This study indicates it is possible to reduce TJA and LESS scores in male youth athletes by performing a 4-week neuromuscular training program, improving landing mechanics and reducing injury risk irrespective of maturity, but their effects are somewhat influenced by stage of maturation and the task performed.
To examine the effects of a progressive injury prevention (IP) program, embedded into school curriculum, on injury rates in young females.
One hundred and three physical education (PE) students [mean ± SD; age = 14.0 ± 0.6 years; height = 162.6 ± 5.8 cm; mass = 57.4 ± 9.8 kg, intervention (INT) n = 53, control (CON) n = 50] from a girls’ secondary school participated in this study. The INT group (competitive athletes) completed a 23-week (three phase) IP program whereas the CON group continued normal PE class. An online questionnaire recorded training and competition exposure and self-reported injuries.
The INT group reported significantly more weekly training and competition hours than the CON group (4.15 ± 4.78 vs. 2.19 ± 3.22, P < 0.001 training hours and 0.77 ± 1.42 vs. 0.55 ± 1.10, P < 0.001 competition hours). There was no difference in any injury rate between the two groups. There was a significant reduction in injury rate between phase 1 and phase 3 of the IP program for the INT group [injury rate ratio = 0.63 (95% CI = 0.41–0.96); P = 0.02]. Injury rates in competition were higher than in training (40.1 and 36.3 injuries per 1000 h competition vs. 13.7 and 9.5 injuries per 1000 h training).
Although there was no difference in injury rates between groups, the IP program did significantly reduce rates with-in the INT group over the duration of the school year and may be protective against increased injury incidence for young females engaged in competitive sports.
To quantify the effects of an externally worn collar device for mitigating the influence of repetitive head impacts on alterations to diffusion tensor imaging (DTI) metrics of white matter.
Fifteen female high-school soccer athletes (age: 14.00–16.98 yrs) completed pre- and post-season DTI over two consecutive years, including measures of diffusivity, changes in which may be associated with brain dysfunction. The collar was worn during year 1 (Yr1) but not during year 2 (Yr2). Athlete exposures (AEs) and head impact exposure were recorded over the competitive seasons.
There were no significant differences in AEs or head impact exposures between Yr1 and Yr2 (P > 0.05). In Yr2, there was significant pre- to post-season mean diffusivity and/or axial diffusivity reduction in multiple WM regions (corrected P < 0.05). Pre- to post-season mean diffusivity, axial diffusivity, and radial diffusivity decreases were 3.04% ± 2.53%, 2.97% ± 2.19%, and 3.37% ± 3.34%, respectively, significantly greater than pre- to post-season changes in Yr1 (mean diffusivity: − 0.31% ± 1.78%, P = 0.0014; axial diffusivity: − 0.02% ± 2.25%, P = 0.0014; radial diffusivity: − 0.63% ± 2.10%, P = 0.0030).
Mild bilateral compression to athletes’ internal jugular vein through collar application may have increased intracranial blood volume and spatially redistributed head-impact-derived brain energy absorption. However, future research is needed to elucidate the potential clinical significance of WM changes of various degrees.
NCT03014492.
Cystic Fibrosis (CF) is a multisystem disease associated with symptoms such as dyspnoea, tachycardia and tachypnea that may be related to changes in autonomic function and sensitive to improvement following inspiratory muscle training (IMT). The aim of the present study was to investigate the effect of IMT on heart rate variability (HRV) and respiratory function in children.
Five CF and five matched controls (40% boys) performed a 4-weeks IMT programme, involving 30 breaths, twice a day. Weeks 1–2 of training were set at 40% of a participant’s maximal strength index (S.Index), with week’s 3–4 set at 50%. Participants wore an ActiHeart for three consecutive days at baseline and post-intervention and indices of HRV were derived. Standard measures of lung function were obtained along with health-related quality of life (HRQoL) using the CF-specific questionnaire (CFQ-R).
IMT elicited clinically meaningful increases in respiratory muscle strength and respiratory symptom domain scores, but no improvements in respiratory volume, irrespective of group. Similarly, no significant improvements were found in HRQoL despite 62.5% of the population increased their HRQoL score. Post-intervention, CF participants showed a clinically meaningful decrease in the very low frequency (VLF) domain.
These results may indicate clinically meaningful changes in HRV and inspiratory muscle strength following a 4-week IMT intervention, although a more powerful study is required to draw further conclusions. Indeed, the trends for improved HRQoL support the need for such studies to ascertain the potential therapeutic role of IMT in those with CF.
Sled towing has been shown to be an effective method to enhance the physical qualities in youth athletes. The aim of this study was to evaluate the impact of a 6-week sled towing intervention on muscular strength, speed and power in elite youth soccer players of differing maturity status.
Seventy-three male elite youth soccer players aged 12–18 years (Pre-Peak Height Velocity [PHV] n = 25; Circa-PHV n = 24; Post-PHV n = 24) from one professional soccer academy participated in this study. Sprint assessments (10 m and 30 m), countermovement jump and isometric mid-thigh pull were undertaken before (T1) and after (T2) a 6-week intervention. The training intervention consisted of 6 weeks (2 × per week, 10 sprints over 20 m distance) of resisted sled towing (linear progression 10%–30% of body mass) during the competitive season. Bayesian regression models analysed differences between T1 and T2 within each maturity group.
There were minimal changes in strength, speed and power (P = 0.35–0.80) for each maturity group across the 6-week intervention. Where there were changes with greater certainty, they are unlikely to represent real effect due to higher regression to the mean (RTM).
It appears that a 6-week sled towing training programme with loadings of 10%–30% body mass only maintains physical qualities in elite youth soccer players pre-, circa-, and post-PHV. Further research is required to determine the effectiveness of this training method in long-term athletic development programmes.
The world’s greatest professional football players are able to execute effective tactical decisions as well as fulfil various physical demands. However, the degree to which both are associated with greater potential in a football academy is unknown. Therefore, the aim of this study was to investigate decision-making skill and physical performance as contributing factors to coach potential rankings in an English football academy. Ninety-eight outfield academy players (Foundation Development Phase [FDP] under-9 to under-11 n = 40; Youth Development Phase [YDP] under-12 to under-16 n = 58) participated in the study. They engaged in 45 film-based simulations at two occlusion phases (e.g., the visual display is cut-off at a precise time during an action), firstly “during” and secondly “post” execution, to examine decision-making skill. Participants also completed four fitness tests to examine physical performance. A classification of “higher-potentials” (top third) and “lower-potentials” (bottom third) were applied through coach rankings. Independent t-tests compared the decision-making and physical performance tests. Higher-potentials made significantly more accurate decisions within the “post” phase within the FDP (P < 0.05) and the “during” phase within the YDP (P < 0.05). Additionally, higher-potentials were significantly faster for the 0–30 m sprint in both the FDP and YDP (P < 0.05), with higher-potentials within the YDP also significantly faster in the 0–10 m sprint (P < 0.05) and jumped significantly higher in the countermovement jump (P < 0.05). These findings indicated that greater football potential may be associated with superior perceptual-cognitive expertise and quicker sprint ability in both academy age phases, with a greater discriminatory function within the older cohort.
This study examined changes in vertical jump performance with progressively greater eccentric pre-loading in relation to growth and development in young female athletes.
Twenty young female athletes ranging from 9 to 17 years old performed the following vertical jumps in random order: static jumps (SJs), counter-movement jumps (CMJs), and drop jumps (DJs) from drop heights of 20, 30, and 40 cm (DJ20, DJ30, and DJ40, respectively). Measurements included peak force (PF), peak rate of force development (RFD), peak power (PP), eccentric impulse (ECC), and concentric impulse (CON). Measurements of growth included age, maturity offset, height, body mass, fat-free mass, and thigh muscle cross-sectional area (CSA).
PF increased from the SJ-DJ20 (P ≤ 0.009), then plateaued from DJ20-DJ40 (P = 1.000). RFD remained the same from SJ-CMJ (P = 1.000), increased from CMJ-DJ20 (P < 0.001), and plateaued from DJ20-DJ40 (P = 0.874). PP increased from the SJ-CMJ (P < 0.001), then plateaued from the CMJ-DJ40 (P ≥ 0.486). CON remained the same across all vertical jumps (P = 1.000), while ECC increased from the SJ-DJ40 (P ≤ 0.038). Jump height (JH) increased from the SJ-CMJ (P < 0.001), decreased from CMJ-DJ20 (P < 0.001), and plateaued from DJ20-DJ40 (P = 1.000). The change in PP from the SJ-CMJ (ΔCMJ-SJ) was related to all measurements of growth except CSA (r = 0.558–0.815).
Young females produced greater power during the CMJ than SJ, but equivalent power from the CMJ-DJ40, despite increases in ECC. Additionally, ΔCMJ-SJ was not related to CSA, which suggests other underlying mechanisms affect stretch–shortening cycle utilization in young female athletes.