Isolated core training improves sprint performance in national-level junior swimmers

Effects of anthropometrics, thrust, and drag on stroke kinematics and 100 m performance of young swimmers using path-analysis modeling

The aim of this study was to understand the interactions between anthropometric, kinetic, and kinematic variables and how they determine the 100 m freestyle performance in young swimmers. Twenty-five adolescent swimmers (15 male and 10 female, aged 15.75 ± 1.01 years) who regularly participated in regional and national competitions were recruited. The 100 m freestyle performance was chosen as the variable to be predicted. A series of anthropometric (hand surface area-HSA), kinetic (thrust and active drag coefficient (CDA )), and kinematic (stroke length (SL); stroke frequency (SF), and swimming speed) variables were measured. Structural equation modeling (via path analysis) was used to develop and test the model. The initial model predicted performance with 90.1% accuracy. All paths were significant (p < 0.05) except the thrust-SL. After deleting this non-significant path (thrust-SL) and recalculating, the model goodness-of-fit improved and all paths were significant (p < 0.05). The predicted performance was 90.2%. Anthropometrics had significant effects on kinetics, which had significant effects on kinematics, and consequently on the 100 m freestyle performance. The cascade of interactions based on this path-flow model allowed for a meaningful prediction of the 100 m freestyle performance. Based on these results, coaches and swimmers should be aware that the swimming predictors can first meaningfully interact with each other to ultimately predict the 100 m freestyle performance.

The role of the biomechanics analyst in swimming training and competition analysis

Swimming analysts aid coaches and athletes in the decision-making by providing evidence-based recommendations. The aim of this narrative review was to report the best practices of swimming analysts that have been supporting high-performance athletes. It also aims to share how swimming analysts can translate applied research into practice. The role of the swimming analyst, as part of a holistic team supporting high-performance athletes, has been expanding and is needed to be distinguished from the job scope of a swimming researcher. As testing can be time-consuming, analysts must decide what to test and when to conduct the evaluation sessions. Swimming analysts engage in the modelling and forecast of the performance, that in short- and mid-term can help set races target-times, and in the long-term provide insights on talent and career development. Races can be analysed by manual, semi-automatic or fully automatic video analysis with single or multi-cameras set-ups. The qualitative and quantitative analyses of the swim strokes, start, turns, and finish are also part of the analyst job scope and associated with race performance goals. Land-based training is another task that can be assigned to analysts and aims to enhance the performance, prevent musculoskeletal injuries and monitor its risk factors.

Shoulder Pain and Trunk Muscles Endurance in Young Male and Female Swimmers

Shoulder pain is a common syndrome in swimming and affects a large number of competitive swimmers. The purpose of the study was to investigate the relationship between pain in the shoulder girdle and the endurance of the trunk muscles in young swimmers. A total of 24 boys and 22 girls, aged 13 to 18 years, participated in the study. The measurements included the completion of a questionnaire (Shoulder Pain and Disability Index, SPADI) and a field test (McGill's Torso Muscular Endurance Test). The total SPADI score correlated weakly and negatively with the endurance time of back muscles in both sexes (r2 = 0.10, p = 0.035), and moderately and negatively in girls (r2 = 0.23, p = 0.023). A weak negative correlation was found between the disability index and the back muscles' endurance time in both sexes (r2 = 0.15, p = 0.007), which was moderate in girls only (r2 = 0.25, p = 0.019). The disability index displayed moderate negative correlations with the right oblique's (r2 = 0.18, p = 0.049) and left oblique's endurance time (r2 = 0.23, p = 0.024) in girls. Weight, body mass index, the total out-of-water training time per week and age significantly affected the endurance times of the trunk muscles in boys and girls (p < 0.05). In conclusion, strengthening the dorsal and the oblique muscles could reduce shoulder pain and disability in young swimmers and especially girls.

Effect of Different Types of Strength Training on Swimming Performance in Competitive Swimmers: A Systematic Review

Background

Strength training is widely used in swimming for improvement in performance. There are several ways to embark on strength training, which to different degrees follows the principle of specificity. There are disagreements in the literature on which training methods lead to the greatest performance improvements and to what degree resistance training must be specific to swimming to transfer to swimming performance.

Objective

The study was undertaken to examine (1) how different approaches to strength training for competitive swimmers can improve swimming performance and (2) which form of strength training resulted in the largest improvement in swimming performance.

Methods

A systematic review of the literature was undertaken using the following databases: PubMed, SPORTDiscus and Scopus. Studies were eligible if they met the following criteria: (1) a training intervention lasting longer than 3 weeks that investigates the effects strength training has on swimming performance, (2) involves youth or older experienced swimmers, (3) involves in-water specific resistance training, dry-land swim-like resistance training or non-specific dry-land strength training and (4) interventions with clear pre- and posttest results stated. Non-English language articles were excluded. Percent change and between-group effect size (ES) were calculated to compare the effects of different training interventions.

Results

A range of studies investigating different strength training methods were examined. The percent change in performance and between-group ES were calculated; 27 studies met the inclusion criteria. The review revealed no clear consensus on which method of strength training was the most beneficial to swimming performance. All methods had intervention groups that increased their swimming performance.

Conclusions

This review shows that swimming differs from other sports as it is performed in water, and this demands a specific way of training. The results show that a combined swimming and strength training regimen seemed to have a better effect on swimming performance than a swim-only approach to training. Based on the principle of specificity and gains in swimming performance, there is not a clear conclusion, as the three main methods of strength training revealed similar gains in swimming performance of 2–2.5%.

Effect of post-activation potentiation using core activation on isometric core strength and countermovement jump variables in university male recreational athletes

Core strengthening exercises have been integrated into the conditioning regimens of sportsmen of all levels. Despite a wealth of evidence, the question of what influence core stability exercises have on jump performance remains unsolved. Only a small percentage of studies have explored effects of standalone core training. The objective of this research was to explore acute changes in countermovement jump (CMJ) performance caused by post-activation potentiation (PAP) adopting core activation exercises. 25 male recreational athletes were recruited as participants. They visited on three occasions-first for familiarisation, following for baseline data using a conventional warmup, and final for repeat data upon inducing PAP. Isometric dynamometer was used to quantify core isometric strength and CMJ variables were evaluated using a Portable performance analysis system with MARS Software. Paired t-test and multivariate analysis were carried out. All core strength metrics reported marked increase at P<0.001 from conventional to PAP warmup. Following CMJ metrics varied significantly: jump height from take-off (P<0.001), jump height from flight (P<0.01), flight time (P<0.01,) and force at free-fall (P<0.001). Core training with PAP is a form of neuromuscular training that has the potential to improve power, agility, and speed by modifying force absorption, active joint stabilisation, and improved movement patterns. These alterations are ascribed to changes in cerebral drive, as well as enhanced motor-unit activation and firing frequency at the muscle level. Before a competition, a core activation warm-up can offer a unique training stimulus and increase performance via an ergogenic response. The core is essential for optimal athletic performance and should not be overlooked.

Efficacy of Core Training in Swimming Performance and Neuromuscular Parameters of Young Swimmers: A Randomised Control Trial

Background: This study aimed to investigate the efficacy of core training in the swimming performance and neuromuscular properties of young swimmers. Methods: Eighteen healthy male swimmers (age: 13 ± 2 years, height: 159.6 ± 14.5 cm, weight: 48.7 ± 12.4 kg) were recruited from the Public Authority for Sports swimming pool in Dammam and randomly assigned to the experimental and control groups. The experimental group performed a six-week core-training program consisting of seven exercises (three times/week) with regular swimming training. The control group maintained its regular training. Swimming performance and neuromuscular parameters were measured pre- and post-interventions. Results: The experimental group benefitted from the intervention in terms of the 50 m swim time (−1.4 s; 95% confidence interval −2.4 to −0.5) compared with the control group. The experimental group also showed improved swimming velocity (+0.1 m.s−1), stroke rate (−2.8 cycle.min−1), stroke length (+0.2 m.cycle−1), stroke index (+0.4 m2·s−1), total strokes (−2.9 strokes), and contraction time for erector spinae (ES; −1.5 ms), latissimus dorsi (LD; −7 ms), and external obliques (EO; −1.9 ms). Maximal displacement ES (DM-ES) (+3.3 mm), LD (0.5 mm), and EO (+2.2 mm) were compared with the baseline values for the experimental group, and TC-ES (5.8 ms), LD (3.7 ms), EO (2.5 ms), DM-ES (0.2 mm), LD (−4.1 mm), and EO (−1.0 mm) were compared with the baseline values for the control group. The intergroup comparison was statistically significant (p < 0.05; DM-ES p > 0.05). Conclusion: The results indicate that a six-week core-training program with regular swimming training improved the neuromuscular properties and the 50 m freestyle swim performance of the experimental group compared with the control group.

Acute and Long-Term Effects of Concurrent Resistance and Swimming Training on Swimming Performance

Dry-land resistance exercise (RT) is routinely applied concurrent to swimming (SWIM) training sessions in a year-round training plan. To date, the impact of the acute effect of RT on SWIM or SWIM on RT performance and the long-term RT-SWIM or SWIM-RT training outcome has received limited attention. The existing studies indicate that acute RT or SWIM training may temporarily decrease subsequent muscle function. Concurrent application of RT-SWIM or SWIM-RT may induce similar physiological alterations. Such alterations are dependent on the recovery duration between sessions. Considering the long-term effects of RT-SWIM, the limited existing data present improvements in front crawl swimming performance, dry-land upper and lower body maximum strength, and peak power in swim turn. Accordingly, SWIM-RT training order induces swimming performance improvements in front crawl and increments in maximum dry-land upper and lower body strength. Concurrent application of RT-SWIM or SWIM-RT training applied within a training day leads in similar performance gains after six to twelve weeks of training. The current review suggests that recovery duration between RT and SWIM is a predisposing factor that may determine the training outcome. Competitive swimmers may benefit after concurrent application with both training order scenarios during a training cycle.

The Effects of Trunk Muscle Training on Physical Fitness and Sport-Specific Performance in Young and Adult Athletes: A Systematic Review and Meta-Analysis

Background

The role of trunk muscle training (TMT) for physical fitness (e.g., muscle power) and sport-specific performance measures (e.g., swimming time) in athletic populations has been extensively examined over the last decades. However, a recent systematic review and meta-analysis on the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes is lacking.

Objective

To aggregate the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes and identify potential subject-related moderator variables (e.g., age, sex, expertise level) and training-related programming parameters (e.g., frequency, study length, session duration, and number of training sessions) for TMT effects.

Data Sources

A systematic literature search was conducted with PubMed, Web of Science, and SPORTDiscus, with no date restrictions, up to June 2021.

Study Eligibility Criteria

Only controlled trials with baseline and follow-up measures were included if they examined the effects of TMT on at least one measure of physical fitness (e.g., maximal muscle strength, change-of-direction speed (CODS)/agility, linear sprint speed) and sport-specific performance (e.g., throwing velocity, swimming time) in young or adult competitive athletes at a regional, national, or international level. The expertise level was classified as either elite (competing at national and/or international level) or regional (i.e., recreational and sub-elite).

Study Appraisal and Synthesis Methods

The methodological quality of TMT studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. A random-effects model was used to calculate weighted standardized mean differences (SMDs) between intervention and active control groups. Additionally, univariate sub-group analyses were independently computed for subject-related moderator variables and training-related programming parameters.

Results

Overall, 31 studies with 693 participants aged 11–37 years were eligible for inclusion. The methodological quality of the included studies was 5 on the PEDro scale. In terms of physical fitness, there were significant, small-to-large effects of TMT on maximal muscle strength (SMD = 0.39), local muscular endurance (SMD = 1.29), lower limb muscle power (SMD = 0.30), linear sprint speed (SMD = 0.66), and CODS/agility (SMD = 0.70). Furthermore, a significant and moderate TMT effect was found for sport-specific performance (SMD = 0.64). Univariate sub-group analyses for subject-related moderator variables revealed significant effects of age on CODS/agility (p = 0.04), with significantly large effects for children (SMD = 1.53, p = 0.002). Further, there was a significant effect of number of training sessions on muscle power and linear sprint speed (p ≤ 0.03), with significant, small-to-large effects of TMT for > 18 sessions compared to ≤ 18 sessions (0.45 ≤ SMD ≤ 0.84, p ≤ 0.003). Additionally, session duration significantly modulated TMT effects on linear sprint speed, CODS/agility, and sport-specific performance (p ≤ 0.05). TMT with session durations ≤ 30 min resulted in significant, large effects on linear sprint speed and CODS/agility (1.66 ≤ SMD ≤ 2.42, p ≤ 0.002), whereas session durations > 30 min resulted in significant, large effects on sport-specific performance (SMD = 1.22, p = 0.008).

Conclusions

Our findings indicate that TMT is an effective means to improve selected measures of physical fitness and sport-specific performance in young and adult athletes. Independent sub-group analyses suggest that TMT has the potential to improve CODS/agility, but only in children. Additionally, more (> 18) and/or shorter duration (≤ 30 min) TMT sessions appear to be more effective for improving lower limb muscle power, linear sprint speed, and CODS/agility in young or adult competitive athletes.

Effects of Dryland Training During the COVID-19 Lockdown Period on Swimming Performance

Purpose: To examine the effect of dryland training during an 11-week lockdown period due to COVID-19 on swimming performance. Methods: Twelve competitive swimmers performed 50- and 300-m maximum-effort tests in their preferred stroke and 200-, 400-, and four 50-m front crawl sprints (4 × 50 m) before and after the lockdown period. Critical speed as an index of aerobic endurance was calculated using (1) 50-, 300-, and (2) 200-, 400-m tests. Blood lactate concentration was measured after the 400- and 4 × 50-m tests. To evaluate strength-related abilities, the dryland tests included handgrip and shoulder isometric strength. Tethered swimming force was measured during a 10-second sprint. During the lockdown period, dryland training was applied, and the session rating of perceived exertion training (sRPE) load was recorded daily. Results: sRPE training load during the lockdown was decreased by 78% (16%), and critical speed was reduced 4.7% to 4.9% compared to prelockdown period (P < .05). Performance time in 200, 300, and 400 m deteriorated 2.6% to 3.9% (P < .05), while it remained unaltered in 4 × 50- and 50-m tests (P > .05). Tethered force increased 9% (10%) (P < .01), but handgrip and shoulder isometric force remained unaltered (P > .05). Blood lactate concentration decreased 19% (21%) after the 400-m test and was unchanged following the 4 × 50-m tests (P > .05). Conclusions: Performance deterioration in the 200, 300, and 400 m indicates reduced aerobic fitness and impaired technical ability, while strength and repeated-sprint ability were maintained. When a long abstention from swimming training is forced, dryland training may facilitate preservation in short-distance but not middle-distance swimming performance.

A Systematic Review and Meta-Analysis: Biomechanical Evaluation of the Effectiveness of Strength and Conditioning Training Programs on Front Crawl Swimming Performance

The objectives of this systematic review were to summarize and evaluate the effectiveness of strength and conditioning trainings on front crawl swimming, starts and turns performance with relevant biomechanical parameters. Four online databases including PudMed, ESCSOhost, Web of Science and SPORTDiscus were searched according to different combination of keywords. 954 articles were extracted from databases, and ultimately 15 articles were included in this study after removal of duplicate and articles screening according to inclusion and exclusion criteria. Meta-analyses were adopted when appropriate and Egger's regression symmetry was adopted to assess the publication bias and the results were presented with forest plots and funnel plots respectively. Fifteen articles studied the effects of strength and resistance, core, and plyometric trainings. The quality of the investigation was assessed by the checklist developed by Downs and Black. Most of the investigations found out that training programs were beneficial to front crawl sprinting swimming performance, stroke biomechanics, force, and muscle strength. First, strength and resistance trainings and core trainings were effective on sprinting performance enhancement. Second, resistance trainings were found to have positive effects on stroke rate. Plyometric trainings were beneficial to start performance, while there was no sufficient evidence for confirming the positive improvement on turn biomechanical, also overall swimming performance, after weeks of plyometric trainings. Strength and Conditioning trainings are suggested to implement in regular training regime regarding to the positive effects on swimming performance, including starts, turns and front crawl swim, and relevant biomechanical parameters, instead of swimming training only. Further research with higher quality is recommended to conduct and more investigations on the training effects to other stroke styles are also suggested.

Effects of Dry-Land Training Programs on Swimming Turn Performance: A Systematic Review

Swimming coaches have prescribed dry-land training programs over the years to improve the overall swimming performance (starts, clean swimming, turns and finish). The main aim of the present systematic review was to examine the effects of dry-land strength and conditioning programs on swimming turns. Four online databases were scrutinised, data were extracted using the Preferred PRISMA guidelines and the PEDro scale was applied. A total of 1259 articles were retrieved from database searches. From the 19 studies which were full-text evaluated, six studies were included in the review process. The review indicated that plyometric, strength, ballistic and core training programs were implemented for improving swimming turn performance. Strength, ballistic and plyometric training focusing on neural enhancement seem to be effective for improving swimming turn performance. The data related to training of the core were not conclusive. Coaches should consider incorporating exercises focusing on improving the neuromuscular factor of the leg-extensor muscles into their daily dry-land training programs. More researches are needed to provide a better understanding of the training methods effects and training organisations for improving swimming turn performance.

Epidemiology of Injuries in National Collegiate Athletic Association Men's Swimming and Diving: 2014-2015 Through 2018-2019

CONTEXT

The National Collegiate Athletic Association (NCAA) has sponsored men's swimming and diving since 1937.

BACKGROUND

Routine examinations of men's swimming and diving injuries are important for identifying emerging injury-related patterns.

METHODS

Exposure and injury data collected in the NCAA Injury Surveillance Program during the 2014-2015 through 2018-2019 academic years were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics, and injury rate ratios were used to examine differences in injury rates.

RESULTS

The overall injury rate was 1.56 per 1000 athlete-exposures (AEs) for swimmers and 1.52 per 1000 AEs for divers. Shoulder (27.0%) injuries accounted for the largest proportion of all swimming injuries, and most injuries were attributed to overuse mechanisms (42.6%). Shoulder (23.3%) and trunk (23.3%) injuries accounted for the largest proportion of all diving injuries, and most injuries resulted from surface contact (32.6%).

CONCLUSIONS

Findings were consistent with existing literature on swimming and diving. The need for continued surveillance, coupled with more robust participation by swimming and diving programs was also highlighted.

Impact of COVID-19 on Swimming Training: Practical Recommendations during Home Confinement/Isolation

The COVID-19 pandemic has had severe effects on communities globally, leading to significant restrictions on all aspects of society, including in sports. Several significant decisions were made to postpone or cancel major swimming events by FINA (Fédération Internationale de Natation). Swimmers were no longer allowed to continue their usual training in swimming pools and were confined to their homes. These unusual circumstances may represent a good opportunity to strengthen different areas of swimmer preparation and potentially enhance performance when resuming regular aquatic training. We searched major databases for relevant information, and the present article provides practical information on home-based training for swimmers of all ages. The COVID-19 crisis and its consequences on the swimming community have created a myriad of challenges for swimmers around the world, including maintaining their fitness level and preparing to return optimally and safely to pool training and competitions. Unfortunately, the mental consequences that might arise after the pandemic may also have an impact. We strongly recommend encouraging the swimmers to consider quarantine as an opportunity for development in specific areas of preparation and learn how to best cope with this special situation of self-isolation and/or "physical distancing" for their mental health and in case a similar situation is faced again in the future.

Seasonal Changes in Breathing Pattern, Trunk Stabilization, and Muscular Power in Paralympic Swimmers

The purpose of this study was to monitor the changes in breathing pattern, trunk muscle stabilization, and upper-body muscular power in Paralympic swimmers throughout a competitive season over three time points: October (T1), March (T2), and August (T3). Six top-level Paralympic swimmers voluntarily participated in this study. The Friedman test, the Bonferroni-Dunn multiple comparison post hoc analysis, and Kendall's W concordance coefficient for the measure of effect were used. A significant difference was found in the breathing pattern, trunk stability, and upper-body power variables from the T1 to T3 season (p < .05). However, no significant changes were found in the T2 season. A long-term assessment of these fitness parameters may be of practical importance for better tailoring the training programs of top-level Paralympic swimmers.

Effect of Dry-Land Core Training on Physical Fitness and Swimming Performance in Adolescent Elite Swimmers

BACKGROUND

We aimed to investigate the effect of a 12-week dry-land core training program on physical fitness and swimming performance in elite adolescent swimmers.

METHODS

Thirty subjects were selected and assigned to the core training group (CTG, n=15) and the traditional weight training group (WTG, n=15) in Seoul, Korea, between Sep and Dec 2016. The field fitness test was performed to determine the isotonic maximum muscular strength (one repetition maximum of deadlift and cable pulldown), anaerobic power (Wingate test), core stability (sports-specific endurance plank), core muscular power (front abdominal power, side abdominal power), muscular endurance of limbs (push-up, endurance jump), and swim performance improvement (personal record). Differences between groups after the exercise intervention were analyzed using two-way analysis of variance with repeated measures.

RESULTS

There were no significant interactions in isotonic maximum strength, anaerobic power (mean power, fatigue index), core muscular power, muscular endurance of limbs (endurance jump), and swim record improvement (P>0.05). The anaerobic peak power (P<0.001), sports-specific endurance plank test (P<0.001), and push-up test (P<0.001) showed significant interaction effects.

CONCLUSION

The 12-week dry-land core training program resulted in statistically significant improvements in anaerobic power, core stability, upper extremity muscular endurance, and swimming performance.

Effects of core strengthening exercise on colon transit time in young adult women

Background/objective

This study investigated the effects of core strengthening exercise (CSE) on colon transit time (CTT) in young adult women.

Methods

Eighty women (mean age 23 years) were enrolled and randomly assigned to participate in a 12-week, instructor-led group CSE program (CSE group [CSEG]; n = 40) or to maintain usual daily activities (control group [CG]; n = 40). 27 participants in the CSEG and 21 participants in the CG completed the study. The CSE program consisted of 60-min sessions, two days a week, for 12 weeks. CTT was measured using a multiple marker technique with a radio-opaque marker. Data were analyzed with a 2-way, repeated measures ANCOVA.

Results

After the 12-week intervention, The CSEG showed significant improvements in trunk flexor power (P = 0.031), peak torque (P = 0.032), and endurance (P = 0.011). The CSEG also showed improvements in the sit-up (P < 0.001) and side-step (P = 0.043) tests compared to the CG. While there was not a significant group difference between the CSEG and CG, left CTT (P = 0.021) and total CTT (P = 0.006) decreased significantly within the CSEG group only.

Conclusion

The 12-week CSE program increased abdominal strength but did not improve CTT compared to the control group. This study also provides preliminary data that CSE may reduce left CTT and total CTT, but additional clinical trials are needed.

Transfer of Dry-Land Resistance Training Modalities to Swimming Performance

A great number of studies focusing on the effects of dry-land resistance training interventions on swimming performance remain inconclusive. It is suggested that transferability of dry-land strength gains to swimming performance appear when dry-land resistance training programs are swim-specific. The main aim of this study was to compare the effects of specific dry-land resistance training on an ergometer with traditional dry-land exercises, and to determine how much of the resistance training effects were transferred to specific swimming conditions. The study included a group of 26 youth competitive male swimmers (age 15.7 ± 0.5 years, height 174.6 ± 6.6 cm, weight 68.4 ± 8.2 kg, training experience 5.8±0.7 years) of regional level. They were randomly allocated to one of two groups: experimental (E) and control (T). Both groups were involved in a 12-week dry-land resistance training concentrated on increasing muscular strength and power output of the upper limbs. Group E used a specialized ergometer (JBA – Zbigniew Staniak), while group T performed traditional resistance exercises. The program consisted of 10 sets of 30 s of exercise with 30 s rest intervals between each set. A two-way repeated measures ANOVA with Tukey HSD post hoc comparisons was used to determine if any significant differences existed between training groups across pretest and posttest conditions. The significance level was set at p ≤ 0.05. Dry-land resistance training modalities were the only differences in training between both groups. Our findings show that rates of transfer are much higher in group E than in group T, which resulted in a significant increase in swimming velocity (by 4.32%, p<0.001; ES=1.23, and 2.78%, p<0.003, ES=0.31, respectively).

Effect of core training on speed, quickness and agility in young male football players

BACKGROUND

Core training effectively improves sport performance. The purpose of this study was to determine the effect of core training on the performance measures of speed, agility and quickness of U19 male football players.

METHODS

A total of 24 young male football players were divided into 12 in the experimental group (aged 18.17±0.72) and 12 in the control group (aged 18.31±0.75). The experimental group performed 30-35 min core training three days a week for eight weeks while the control group continued their routine training. Measurements included a 40-meter sprint test for speed, a hexagon test for quickness and an agility-T test for agility. Pre-test measurements at the start of the study and post-test measurements after eight weeks were compared by an ANOVA 2×2. A significant level of P<0.05 was established.

RESULTS

In the experimental group, there were an improvement in quickness (pre: 17.27±3.24"; post: 16.79±3.09"; P=0.005, η²=0.53) and agility (pre: 12.86±1.17"; post: 12.38±1.12"; P=0.003, η²=0.56), but the speed did not change (pre: 6.14±0.57"; post: 6.00±0.45", P=0.653).

CONCLUSIONS

The use of core training in combination with normal football training is shown to be effective in improving quickness and agility but not speed among young male football players after a period of eight weeks. So, it appears reasonable to include specific core training programs within football training.

Relationship between thrust, anthropometrics, and dry-land strength in a national junior swimming team

Objectives: This study aimed to (i) assess an anthropometric and thrust inter-limb asymmetry, and; (ii) determine the contribution of anthropometrics, and dry-land upper-body strength and power to the thrust of talented adolescent swimmers. Methods: Eighteen talented adolescent swimmers (12 boys and 6 girls: 15.81 ± 1.62 years old) were evaluated. A set of anthropometric, dry-land upper-body strength and power, and in-water thrust were assessed. Results: Despite the fact that the dominant side presented higher values in anthropometrics (except for the hand surface area) and thrust, non-significant inter-limb differences were found. The symmetry index indicated a symmetry between upper-limbs. Hierarchical linear modeling retained as main predictors of each upper-limb thrust the respective hand surface area (dominant upper limb: estimate = 0.293, 95CI: 0.117; 0.469, p = 0.005; non-dominant upper limb: estimate = 0.295, 95CI: 0.063; 0.526, p = 0.025). The full stroke cycle retained the upper-body dry-land strength as main predictor (estimate = 0.397, 95CI: 0.189; 0.605, p = 0.002). Conclusion: The hand surface area and upper-body strength were the main predictors of each upper-limb and full stroke cycle thrust, respectively. Hence, coaches and practitioners should aim to carefully maximize the hand surface area (by finger spreading) while performing the stroke, as well as dry-land upper-body strength in order to enhance the performance.

The effects of a 6-week core exercises on swimming performance of national level swimmers

The aim of this study was to assess the impact of a 6-week specialized training program aimed at strengthening core muscles to improve the effectiveness of selected elements of a swimming race on a group of Polish swimmers. Sixteen male national level swimmers (21.6 ± 2.2 years) participated in the research. The competitors were randomly assigned to 1 of 2 groups before the data collection process: an experimental (EG, n = 8) and a control (CG, n = 8) group. Both groups of swimmers underwent the same training program in the water environment (volume and intensity), while swimmers from the EG additionally performed specific core muscle training. The task of the swimmers was an individual front crawl swim of 50 m, during which the kinematic parameters of the start jump, turn and swimming techniques were recorded using a video camera system. In both groups, a minor increase in the flight phase was observed at the start (EG = 0.06 m, 1.8%; p = 0.088; CG = 0.08 m, 2.7%; p = 0.013). The time to cover a distance of 5 m after the turn and the recorded average speed in swimming this distance for the EG statistically significantly improved by 0.1 s (-28.6%; p < 0.001) and 3.56 m∙s-1 (23.2%; p = 0.001), respectively. In the EG, a statistically significant improvement in 50 m front crawl swimming performance of 0.3 s (-1.2%, p = 0.001) was observed. The results of the research show that the implementation of isolated strengthening of the stabilizing muscles seems to be a valuable addition to the standard training of swimmers.

In-Season Strength Training in Elite Junior Swimmers: The Role of the Low-Volume, High-Velocity Training on Swimming Performance

The aim of this study was to analyze the effect of long-term combined strength training (ST) and plyometrics on strength, power and swimming performances in elite junior swimmers during a competitive season. Ten elite junior swimmers (5 women and 5 men) completed the study (age: 16.6 ± 0.7 years; mass: 62.2 ± 5.4 kg; stature: 1.70 ± 0.07 m). The participants trained twice a week during 20 weeks. The ST program consisted of upper- and lower limbs exercises with low loads and low volume, lifting the load at maximal intended velocity. The effect of the training protocol was assessed using the 1RM in the full squat (SQ) and bench press (BP), jump height (CMJ), the maximal number of repetitions completed in the pull-up (PU) exercise and time during 50-m freestyle. Training program resulted in significant improvements in CMJ (12.1%, ES: 0.57), maximal dynamic strength in the SQ (16.4%, ES: 0.46) and BP (12.1%, ES: 0.34) exercises, the maximum number of repetitions completed during the PU test (90.7%, ES: 0.57) and swimming performance (-3.9%, ES: 0.45). There were no significant differences between both genders. The relative changes in swimming performance showed significant relationship with the relative changes in 1RM of SQ for pooled data (r=-0.66, p<0.05) and the relative changes in the PU exercise in female swimmers (r=-0.99, p<0.05). Therefore, coaches and strength and conditioning professionals should consider including in-season dry-land ST programs within the training routine in order to obtain further improvements in swimming performance.

Does trunk and hip muscles strength predict performance during a core stability test?

BACKGROUND

A better understanding about the relationship between trunk and hip muscles strength and core stability may improve evaluation and interventions proposed to improve core stability.

OBJECTIVES

To investigate if trunk and hip muscles strength predict pelvic posterior rotation during the bridge test with unilateral knee extension.

METHODS

This is a cross-sectional study. Sixty-one healthy individuals of both sexes (age, 28±6.4 years, weight, 66.5±10.9kg, height, 167±9.5cm) performed the bridge test with unilateral knee extension. The pelvic posterior rotation during the bridge test was obtained with two-dimensional video analysis. Isometric strength of the trunk extensors and rotators, and hip abductors, external and internal rotators and extensors were measured with a hand-held dynamometer. Multiple linear regression analysis was performed to identify if the strength variables could explain the pelvic posterior rotation during the test.

RESULTS

Muscle strength predicted pelvic posterior rotation during the bridge test (r=0.54; p=0.003). Strength of the trunk rotators (p=0.045) and hip internal rotators (p=0.015) predicted reduced magnitude of pelvic posterior rotation during the bridge test, and strength of the hip extensors (p=0.003) predicted increased magnitude of pelvic posterior rotation.

CONCLUSIONS

Trunk rotators and hip internal rotators and extensors strength predict 29% of the performance during the bridge test with unilateral knee extension. The strength of these muscles should be evaluated in individuals with increased pelvic posterior rotation during the bridge test with unilateral knee extension.

Does Plantar Pressure Distribution Influence the Lumbar Multifidus Muscle Thickness in Asymptomatic Individuals? A Preliminary Study

BACKGROUND

Atrophy can occur in the lumbar multifidus (LM) muscle quickly as a result of various musculoskeletal problems. Knowing factors influencing muscle thickness of the LM will provide important clues about lumbopelvic stability.

OBJECTIVES

Although there are several studies in the literature investigating the adverse effects of foot-ankle postural disorders on the lumbopelvic region, to our knowledge there has been no investigation of plantar pressure distribution (PPD) as a factor influencing muscle thickness of the LM. The aim of this study was to determine whether PPD could affect LM muscle thickness.

METHODS

This observational study consisted of 25 asymptomatic individuals. Ultrasonographic imaging was used to determine the thickness of the LM. All participants were subjected to PPD analysis using the Digital Biometry Scanning System and Milletrix software in 9 different plantar pressure zones. The Pearson product-moment correlation coefficients were used to examine the correlations between the LM muscle thickness and other variables. Stepwise multiple linear regression analysis was used to determine the variables with the greatest influence on LM muscle thickness.

RESULTS

Peak pressures of medial and lateral zones of the heel were the significant and independent factors influencing static LM thickness, with 39.5% of the variance; moreover, the peak pressures of heel medial and fourth metatarsal bone were the significant and independent factors influencing dynamic LM thickness, with 38.7% of the variance.

CONCLUSIONS

Plantar pressure distribution could be an important factor influencing LM thickness, although further research is required. Examining foot-ankle biomechanics may provide information about the stability of the LM.

Resistance Training for Children and Adolescents

Resistance training is becoming more important as an integral part of comprehensive sport training regimens, school physical education classes, and after-school fitness programs. The increasing number of youth who are involved in sport activities, coupled with the health problems of inactivity and being overweight, have resulted in increased interest in resistance training. Secular declines in measures of muscular fitness in modern-day youth highlight the need for participation in youth resistance training for nonathletes as well as athletes. Parents often ask pediatricians to offer advice regarding the safety, benefits, and implementation of an effective resistance-training program. This report is a revision of the 2008 American Academy of Pediatrics policy statement and reviews current information and research on the benefits and risks of resistance training for children and adolescents.

Nonspecific Resistance Training and Swimming Performance: Strength or Power? A Systematic Review

Muniz-Pardos, B, Gomez-Bruton, A, Matute-Llorente, A, Gonzalez-Aguero, A, Gomez-Cabello, A, Gonzalo-Skok, O, Casajus, JA, and Vicente-Rodriguez, G. Nonspecific resistance training and swimming performance: Strength or power? A systematic review. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this systematic review was to determine the type of nonspecific resistance intervention that is more effective to enhance swimming performance and to determine the nonspecific strength- or power-related variable that better predicts swimming performance. A search was conducted on PubMed, Cochrane Plus, and SportDiscus up to June 2018. Studies were distributed into 4 categories: dry-land strength (DLS), dry-land power (DLP), combination of training methods, and strength and power in start performance. From 1,844 citations, 33 met the inclusion criteria. Cross-sectional DLS studies showed positive associations between swimming performance and DLS development (especially through upper-body isometric assessments), although the efficacy of DLS training interventions remains unclear. Dry-land power training (principally through plyometrics) was a proficient, nonspecific method to enhance swimming block start performance (SBS; the start phase off the block and during the first 5-15 m), and jump assessment was the best predictor of SBS. Some pioneering nonspecific practices such as the acute exposure to high altitude or the maintenance of a high core temperature during the transition phase before competition seem to improve performance, although more research is required to confirm their efficacy. Further high-quality intervention studies are required to clarify the effect of DLP training on sprint swimming performance.

Relationships Between Dry-land Resistance Training and Swim Start Performance and Effects of Such Training on the Swim Start: A Systematic Review

BACKGROUND

The swim start requires an explosive muscular response of the lower body musculature to effectively initiate movement off the starting blocks. There are currently key gaps in the literature evaluating the relationship between dry-land resistance training and swim start performance and the effects of this training on swim start performance, as assessed by the time to 5, 10 or 15 m.

OBJECTIVES

The aims of this systematic review were to critically appraise the current literature on (1) the acute relationship between dry-land resistance training and swim start performance and (2) the acute and chronic effects of dry-land resistance training on swim start performance.

METHODS

An electronic search using AusportMed, Embase, Medline (Ovid), SPORTDiscus and Web of Science was performed. The methodological quality of the studies was evaluated using the Newcastle-Ottawa quality assessment scale (NOS) (cross-sectional studies) and the Physiotherapy Evidence Database (PEDro) scale (intervention studies).

RESULTS

Sixteen studies met the eligibility criteria, although the majority did not utilise the starting blocks or technique currently used in elite swimming. Swim start performance was near perfectly related (r > 0.90) to vertical bodyweight jumps and jump height. Post-activation potentiation and plyometrics were found to produce significant improvements in acute and chronic swim start performance, respectively.

CONCLUSION

While there appears to be strong evidence supporting the use of plyometric exercises such as vertical jumps for monitoring and improving swim start performance, future studies need to replicate these findings using current starting blocks and techniques and compare the chronic effects of a variety of resistance training programmes.

Effect of core training on dynamic balance and agility among Indian junior tennis players

BACKGROUND

The effect of core training on dynamic balance and agility has yet to be established in literature, especially among junior athletes.

OBJECTIVE

To investigate the effect of core training on dynamic balance and agility among Indian junior tennis players.

METHOD

Thirty junior tennis players from various parts of Delhi and the national capital region participated in the study. The study featured a pre-test/post-test experimental design. The subjects were divided into the experimental group (mean age = 15.20 ± 0.41, mean BMI = 20.23 ± 1.54) and the control group (mean age = 15.53 ± 1.06, mean BMI = 20.71 ± 1.53). The control group performed regular training, and the experimental group followed a five-week core training program along with regular training. The subjects were evaluated with t-test for agility and the Star Excursion Balance Test (SEBT) for dynamic stability.

RESULTS

A significant difference was found in the post-test values of agility (t-test p= 0.000) and dynamic balance using SEBT ((anterolateral; p= 0.00), (lateral; p= 0.02), (posterolateral; p= 0.00), (posterior; p= 0.00), (posteromedial; p= 0.01), (medial; p= 0.03), and (anteromedial; p= 0.03)] except in the anterior direction (p= 0.23)) between the experimental and the control group. The experimental group showed a significant difference in the pre- and post-test values of the t-test and SEBT except in the anterior direction.

CONCLUSION

Core training programs can be incorporated safely with players' regular training to improve their dynamic balance and agility, which can eventually lead to better performance.

The Impact of Resistance Training on Swimming Performance: A Systematic Review

BACKGROUND

The majority of propulsive forces in swimming are produced from the upper body, with strong correlations between upper body strength and sprint performance. There are significant gaps in the literature relating to the impact of resistance training on swimming performance, specifically the transfer to swimming performance.

OBJECTIVE

The aims of this systematic literature review are to (1) explore the transfer of resistance-training modalities to swimming performance, and (2) examine the effects of resistance training on technical aspects of swimming.

METHODS

Four online databases were searched with the following inclusion criteria: (1) journal articles with outcome measures related to swimming performance, and (2) competitive swimmers participating in a structured resistance-training programme. Exclusion criteria were (1) participants with a mean age <16 years; (2) untrained, novice, masters and paraplegic swimmers; (3) triathletes and waterpolo players; (4) swimmers with injuries or illness; and (5) studies of starts and turns specifically. Data were extracted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the Physiotherapy Evidence Database (PEDro) scale was applied.

RESULTS

For optimal transfer, specific, low-volume, high-velocity/force resistance-training programmes are optimal. Stroke length is best achieved through resistance training with low repetitions at a high velocity/force. Resisted swims are the most appropriate training modality for improving stroke rate.

CONCLUSION

Future research is needed with respect to the effects of long-term resistance-training interventions on both technical parameters of swimming and overall swimming performance. The results of such work will be highly informative for the scientific community, coaches and athletes.

Dry-Land Resistance Training Practices of Elite Swimming Strength and Conditioning Coaches

Crowley, E, Harrison, AJ, and Lyons, M. Dry-land resistance training practices of elite swimming strength and conditioning coaches. J Strength Cond Res 32(9): 2592-2600, 2018-No research to date has investigated dry-land resistance (RT) training practices of elite swimming strength and conditioning coaches. This is the first comprehensive study exploring dry-land RT training practices in swimming. The aims of this study were to examine (a) the dry-land RT training practices and exercises used by elite swimming strength and conditioning coaches and (b) the rationale provided by coaches about their practices and prescription of specific dry-land RT training exercises. Twenty-three (n = 21 males, n = 2 females) elite swimming strength and conditioning coaches, from Ireland (n = 7), Great Britain (n = 5), Australia (n = 6), and the United States of America (n = 5) were recruited through their specific national governing bodies. Coaches completed an online questionnaire consisting of 7 sections; subject information, informed consent, coach's biography, coach education, current training commitments, dry-land RT training practices and exercises, and additional information. The results showed that coaches had varying levels of experience, education and worked with different level swimmers. A total of 95 dry-land RT training exercises were used by the coaches across 4 different dry-land RT training practices (warm-up, circuit training, traditional RT training and plyometrics). Traditional RT training (87%) was the most commonly practiced. The pull-up and squat were the most popular dry-land RT training exercises used by elite swimming strength and conditioning coaches. Future research needs to focus on exploring the specificity and the transfer of RT training exercises to swimming performance.

Effects of ten weeks dynamic or isometric core training on climbing performance among highly trained climbers

This is the first study to compare the effects of isometric vs. dynamic core training and characterize core-training adaptations using climbing-specific performance and core strength tests in elite climbers. The aim of the study was to compare the effects of attending a progressive core-training program on climbing performance. 19 advanced and elite climbers (7.3±5.6 years climbing experience, red point skill grade 19 IRCRA) were randomized into a dynamic (DCT) or isometric (ICT) core training group and trained twice weekly for ten weeks. The climbers were tested using two climbing-specific core tests (body lock-off and body-lift) and four non-specific core strength tests-one dynamic (superman) and three isometric (trunk flexion and trunk rotation left and right). Between group comparisons showed no differences between the groups at post-test (p = 0.328-0.824) and neither group demonstrated greater improvement compared with the other (p = 0.300-0.926). The ICT group demonstrated 10.8% and 29.6% improvement in trunk flexion and body-lift (p = 0.029-0.037 with no improvement in body lock-off and rotation (p = 0.101-0.343). The DCT group demonstrated 5.0-14.9% improvement in the core strength tests (p = 0.012-0.043), a non-significant 33.8% improvement in body-lift (p = 0.100) and no improvement in body lock-off (p = 0.943). In conclusion, none of the training groups demonstrated greater improvement than the other and both dynamic and isometric core training improved climbing-specific test performance. Dynamic training was slightly more favorable although not significantly superior to isometric core training in improving core strength.

The Effects of Concurrent Strength and Endurance Training on Physical Fitness and Athletic Performance in Youth: A Systematic Review and Meta-Analysis

Combining training of muscle strength and cardiorespiratory fitness within a training cycle could increase athletic performance more than single-mode training. However, the physiological effects produced by each training modality could also interfere with each other, improving athletic performance less than single-mode training. Because anthropometric, physiological, and biomechanical differences between young and adult athletes can affect the responses to exercise training, young athletes might respond differently to concurrent training (CT) compared with adults. Thus, the aim of the present systematic review with meta-analysis was to determine the effects of concurrent strength and endurance training on selected physical fitness components and athletic performance in youth. A systematic literature search of PubMed and Web of Science identified 886 records. The studies included in the analyses examined children (girls age 6–11 years, boys age 6–13 years) or adolescents (girls age 12–18 years, boys age 14–18 years), compared CT with single-mode endurance (ET) or strength training (ST), and reported at least one strength/power—(e.g., jump height), endurance—(e.g., peak V°O₂, exercise economy), or performance-related (e.g., time trial) outcome. We calculated weighted standardized mean differences (SMDs). CT compared to ET produced small effects in favor of CT on athletic performance (n = 11 studies, SMD = 0.41, p = 0.04) and trivial effects on cardiorespiratory endurance (n = 4 studies, SMD = 0.04, p = 0.86) and exercise economy (n = 5 studies, SMD = 0.16, p = 0.49) in young athletes. A sub-analysis of chronological age revealed a trend toward larger effects of CT vs. ET on athletic performance in adolescents (SMD = 0.52) compared with children (SMD = 0.17). CT compared with ST had small effects in favor of CT on muscle power (n = 4 studies, SMD = 0.23, p = 0.04). In conclusion, CT is more effective than single-mode ET or ST in improving selected measures of physical fitness and athletic performance in youth. Specifically, CT compared with ET improved athletic performance in children and particularly adolescents. Finally, CT was more effective than ST in improving muscle power in youth.

Sport-Specific Assessment of the Effectiveness of Neuromuscular Training in Young Athletes

Neuromuscular training in young athletes improves performance and decreases the risk of injuries during sports activities. These effects are primarily ascribed to the enhancement of muscle strength and power but also balance, speed and agility. However, most studies have failed to demonstrate significant improvement in these abilities. This is probably due to the fact that traditional tests do not reflect training methods (e.g., plyometric training vs. isometric or isokinetic strength testing, dynamic balance training vs. static balance testing). The protocols utilized in laboratories only partially fulfill the current needs for testing under sport-specific conditions. Moreover, laboratory testing usually requires skilled staff and a well equipped and costly infrastructure. Nevertheless, experience demonstrates that high-technology and expensive testing is not the only way to proceed. A number of physical fitness field tests are available today. However, the low reliability and limited number of parameters retrieved from simple equipment used also limit their application in competitive sports. Thus, there is a need to develop and validate a functional assessment platform based on portable computerized systems. Variables obtained should be directly linked to specific features of particular sports and capture their complexity. This is essential for revealing weak and strong components of athlete performance and design of individually-tailored exercise programs. Therefore, identifying the drawbacks associated with the assessment of athlete performance under sport-specific conditions would provide a basis for the formation of an innovative approach to their long-term systematic testing. This study aims (i) to review the testing methods used for the evaluation of the effect of neuromuscular training on sport-specific performance in young athletes, (ii) to introduce stages within the Sport Longlife Diagnostic Model, and (iii) to propose future research in this topic. Analysis of the literature identified gaps in the current standard testing methods in terms of their low sensitivity in discriminating between athletes of varied ages and performance levels, insufficent tailoring to athlete performance level and individual needs, a lack of specificity to the requirements of particular sports and also in revealing the effect of training. In order to partly fill in these gaps, the Sport Longlife Diagnostic Model was proposed.

Resistance Training in Youth: Laying the Foundation for Injury Prevention and Physical Literacy

CONTEXT

The rising incidence of physical activity- and sports-related injuries has prompted the present-day investigation of resistance training as a potential means of injury prevention and physical literacy development among youth.

EVIDENCE ACQUISITION

Relevant studies on the topics of athlete development, physical literacy, resistance training, and injury prevention in children and adolescents were reviewed (PubMed and Sports Discus, 1982-2016). Recommendations from consensus guidelines and position statements applicable to resistance training and injury prevention in youth, in addition to young athlete development, were reviewed. Additionally, hand searches, expert requests, article reference lists, and gray literature were utilized and reviewed for pertinent content.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Youth throughout the physical activity spectrum are at risk for physical activity- and sports-related injury. Of highest priority are early specializers, physically inactive youth, and young girls, owing to increased injury rates. Resistance training among these at-risk populations has been shown to reduce injury risk by up to 68% and improve sports performance and health measures, in addition to accelerating the development of physical literacy. Recent recommendations, position statements, and national initiatives advocate for the incorporation of resistance training with qualified instruction among these groups.

CONCLUSION

Resistance training in addition to free play and other structured physical activity training can serve as a protective means against injury and a positive catalyst for the development of physical literacy to offset the impact of diminishing physical activity and early sport specialization in today's youth.

The Role of Trunk Muscle Strength for Physical Fitness and Athletic Performance in Trained Individuals: A Systematic Review and Meta-Analysis

BACKGROUND

The importance of trunk muscle strength (TMS) for physical fitness and athletic performance has been demonstrated by studies reporting significant correlations between those capacities. However, evidence-based knowledge regarding the magnitude of correlations between TMS and proxies of physical fitness and athletic performance as well as potential effects of core strength training (CST) on TMS, physical fitness and athletic performance variables is currently lacking for trained individuals.

OBJECTIVE

The aims of this systematic review and meta-analysis were to quantify associations between variables of TMS, physical fitness and athletic performance and effects of CST on these measures in healthy trained individuals.

DATA SOURCES

PubMed, Web of Science, and SPORTDiscus were systematically screened from January 1984 to March 2015.

STUDY ELIGIBILITY CRITERIA

Studies were included that investigated healthy trained individuals aged 16-44 years and tested at least one measure of TMS, muscle strength, muscle power, balance, and/or athletic performance.

STUDY APPRAISAL AND SYNTHESIS METHODS

Z-transformed Pearson's correlation coefficients between measures of TMS and physical performance were aggregated and back-transformed to r values. Further, to quantify the effects of CST, weighted standardized mean differences (SMDs) of TMS and physical performance were calculated using random effects models. The methodological quality of CST studies was assessed by the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Small-sized relationships of TMS with physical performance measures (-0.05 ≤ r ≤ 0.18) were found in 15 correlation studies. Sixteen intervention studies revealed large effects of CST on measures of TMS (SMD = 1.07) but small-to-medium-sized effects on proxies of physical performance (0 ≤ SMD ≤ 0.71) compared with no training or regular training only. The methodological quality of CST studies was low (median PEDro score = 4).

CONCLUSIONS

Our findings indicate that TMS plays only a minor role for physical fitness and athletic performance in trained individuals. In fact, CST appears to be an effective means to increase TMS and was associated with only limited gains in physical fitness and athletic performance measures when compared with no or only regular training.

Effects of Resistance Training in Youth Athletes on Muscular Fitness and Athletic Performance: A Conceptual Model for Long-Term Athlete Development

During the stages of long-term athlete development (LTAD), resistance training (RT) is an important means for (i) stimulating athletic development, (ii) tolerating the demands of long-term training and competition, and (iii) inducing long-term health promoting effects that are robust over time and track into adulthood. However, there is a gap in the literature with regards to optimal RT methods during LTAD and how RT is linked to biological age. Thus, the aims of this scoping review were (i) to describe and discuss the effects of RT on muscular fitness and athletic performance in youth athletes, (ii) to introduce a conceptual model on how to appropriately implement different types of RT within LTAD stages, and (iii) to identify research gaps from the existing literature by deducing implications for future research. In general, RT produced small-to-moderate effects on muscular fitness and athletic performance in youth athletes with muscular strength showing the largest improvement. Free weight, complex, and plyometric training appear to be well-suited to improve muscular fitness and athletic performance. In addition, balance training appears to be an important preparatory (facilitating) training program during all stages of LTAD but particularly during the early stages. As youth athletes become more mature, specificity, and intensity of RT methods increase. This scoping review identified research gaps that are summarized in the following and that should be addressed in future studies: (i) to elucidate the influence of gender and biological age on the adaptive potential following RT in youth athletes (especially in females), (ii) to describe RT protocols in more detail (i.e., always report stress and strain-based parameters), and (iii) to examine neuromuscular and tendomuscular adaptations following RT in youth athletes.

Effects and dose-response relationships of resistance training on physical performance in youth athletes: a systematic review and meta-analysis

Objectives

To quantify age, sex, sport and training type-specific effects of resistance training on physical performance, and to characterise dose–response relationships of resistance training parameters that could maximise gains in physical performance in youth athletes.

Design

Systematic review and meta-analysis of intervention studies.

Data sources

Studies were identified by systematic literature search in the databases PubMed and Web of Science (1985–2015). Weighted mean standardised mean differences (SMD_wm) were calculated using random-effects models.

Eligibility criteria for selecting studies

Only studies with an active control group were included if these investigated the effects of resistance training in youth athletes (6–18 years) and tested at least one physical performance measure.

Results

43 studies met the inclusion criteria. Our analyses revealed moderate effects of resistance training on muscle strength and vertical jump performance (SMD_wm 0.8–1.09), and small effects on linear sprint, agility and sport-specific performance (SMD_wm 0.58–0.75). Effects were moderated by sex and resistance training type. Independently computed dose–response relationships for resistance training parameters revealed that a training period of >23 weeks, 5 sets/exercise, 6–8 repetitions/set, a training intensity of 80–89% of 1 repetition maximum (RM), and 3–4 min rest between sets were most effective to improve muscle strength (SMD_wm 2.09–3.40).

Summary/conclusions

Resistance training is an effective method to enhance muscle strength and jump performance in youth athletes, moderated by sex and resistance training type. Dose–response relationships for key training parameters indicate that youth coaches should primarily implement resistance training programmes with fewer repetitions and higher intensities to improve physical performance measures of youth athletes.