Effect of Different Physical Training Forms on Change of Direction Ability: a Systematic Review and Meta-analysis

Effects of Postactivation Potentiation enhacement on sprint and change-of-direction performance in athletes: A systematic review

BACKGROUND

Training interventions like Resisted Sled Training, Complex Training, Plyometric training, and recently, Postactivation Potentiation Enhancement (PAPE) protocols are being employed by sportsmen for performance enhancement. Currently, there is no conclusive evidence on the effectiveness of the PAPE protocols and methods to integrate them into the training. The current systematic review aims to critically summarize the current evidence on PAPE protocols' effect on Sprint and Change of Direction (COD) performance in Athletes and study the influence of the Type of PAPE protocols, Recovery duration, Volumes, and loads of PAPE protocols.

METHODS

A systematic computerized literature search was performed from December 2020 to June 2022 on the databases: MEDLINE (assessed by PubMed), CENTRAL (Cochrane Library Central Register of Controlled Trials), PeDro, and Science direct. The major criteria for inclusion were Athletes (Population) who performed PAPE protocol as Intervention before Sprint and/or COD assessment tests. The studies were individually assessed for Risk of Bias using EPHPP (Effective Public Health Practice Project) Tool.

RESULTS

A total of sixteen studies were included. For Linear sprint, nine studies reported a significant PAPE effect whereas, six studies reported insignificant effects. Whereas, for COD performance, two studies reported insignificant results and one study reported significant CODS enhancements The recovery duration ranged from 15 s up to 16 min.

CONCLUSION

PAPE protocols can be incorporated provided the recovery duration is of Moderate duration (3-8mins) or Individualized durations, using multiple sets (2-6), moderate-high loads (>85% 1-RM), type of protocol is Barbell Hip Thrust, Plyometrics or Unilateral biomechanically similar exercises to Running.

Active video games for improving health-related physical fitness in older adults: a systematic review and meta-analysis

Background

The global population is experiencing a rapid rise in the quantity and percentage of older people. In an effort to enhance physical activity among older adults, active video games (AVGs) are being suggested as a compelling alternative and are currently under scrutiny to evaluate their efficacy in promoting the health of older people.

Objective

This review aims to synthesize current studies and formulate conclusions regarding the impact of AVGs on the health-related physical fitness of older adults.

Methods

Seven databases (PubMed, Web of Science, SCOPUS, SPORTDiscus, EMBASE, MEDLINE, and CINAHL) were searched from inception to January 21, 2024. Eligible studies included randomized controlled trials examining the effect of AVGs compared to control conditions on health-related physical fitness outcomes in older adults. The methodological quality of the included trials was assessed using the PEDro scale, and the certainty of evidence was evaluated using the GRADE approach. A random-effects model was used to calculate effect sizes (ES; Hedge's g) between experimental and control groups.

Results

The analysis included 24 trials with a total of 1428 older adults (all ≥ 60 years old). Compared to controls, AVGs produced significant increases in muscular strength (moderate ES = 0.64-0.68, p < 0.05) and cardiorespiratory fitness (moderate ES = 0.79, p < 0.001). However, no significant effects were found for body composition (trivial ES = 0.12-0.14; p > 0.05) and flexibility (trivial ES = 0.08; p = 0.677). The beneficial effects of AVGs were greater after a duration of ≥ 12 vs. < 12 weeks (cardiorespiratory fitness; ES = 1.04 vs. 0.29, p = 0.028) and following ≥ 60 minutes vs. < 60 minutes of session duration (muscular strength; ES = 1.20-1.24 vs. 0.27-0.42, p < 0.05).

Conclusion

AVGs appear to be an effective tool for enhancing muscular strength and cardiorespiratory fitness in older adults, although their impact on improving body composition and flexibility seems limited. Optimal improvement in cardiorespiratory fitness is associated with a longer duration of AVGs (≥ 12 weeks). Moreover, a session duration of ≥ 60 minutes may provide greater benefits for the muscular strength of older adults.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=482568, identifier CRD42023482568.

Comparison of kinematics and electromyography in the last repetition during different maximum repetition sets in the barbell back squat

Background

The barbell squat is an exercise used to strengthen the lower limbs, with implications for both performance in sports and improving movement during everyday tasks. Although the exercise is being trained across a variety of repetition ranges, the technical requirements may vary, affecting appropriate repetition range for specific training goals.

Methods

A randomised within-subject design was used to compare kinematics and surface electromyography (EMG) in the lower extremities during different concentric phases (pre-, sticking- and post-sticking region) of the last repetition when performing squats at different repetition maximums (RMs). Thirteen strength-trained men (age: 23.6 ± 1.9 years; height: 181.1 ± 6.5 cm; body mass: 82.2 kg, 1RM: 122.8 ± 16.2, relative strength: 1.5 ± 0.2 x body mass in external load) performed a 1, 3, 6, and 10RM squat, in a randomised order.

Results

The main findings were that barbell-, ankle-, knee- and hip kinematics were similar across different repetition ranges, except for a smaller trunk lean at 1RM in the pre-sticking region compared to other repetitions and in the sticking region compared to 10RM (p ≤ 0.04). Furthermore, 1RM revealed significantly higher EMG amplitude in the vastus lateralis, gastrocnemius and soleus in the sticking and post-sticking regions when compared to 10RM. It was concluded that 10RM may locally fatigue the vastus lateralis and plantar flexors, explaining the lower EMG amplitude. The observed differences indicate that requirements vary for completing the final repetition of the 10RM compared to the 1RM, an important aspect to consider in training to enhance 1RM strength.

Postural Balance in Boys With Intellectual Disabilities Who Participate in Soccer Training

PURPOSE

The aim of this study is to investigate the postural balance in children with intellectual disabilities who participate in soccer training compared with their sedentary peers.

METHOD

Two groups of boys with intellectual disabilities aged 8-10 years participated in this study: a soccer group (n = 12) and a sedentary group (n = 12). Postural balance was assessed using a force platform under 4 different conditions: open eyes, and closed eyes, on firm and foam surfaces. The Timed Up and Go Test, 10-m Walking Test, and Four-Square Step Test were also conducted.

RESULTS

The soccer group had significantly lower (P < .05) center of pressure values compared with the sedentary group, on both firm and foam surfaces, but only under the open eyes condition. They were significantly faster (P < .05) in the Timed Up and Go Test, 10-m Walking Test, and Four-Square Step Test compared with their sedentary peers. However, there were no significant differences between the 2 groups on the sit-to-stand and turn-to-sit phases of the Timed Up and Go Test.

CONCLUSION

Soccer participation may have a positive effect on postural balance in boys with intellectual disabilities. These findings may have implications for the development of exercise programs to improve postural balance and reduce the risk of falls in this population.

Male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction

Change of direction manoeuvres is important in soccer and associated with non-contact anterior cruciate ligament injury, yet it is not known how the mechanics differentiate between males and females during 180° turns. Twenty-eight soccer players (14 males and 14 females) performed 180° turns with ground reaction forces collected over penultimate and final contacts. A two-way (contact × limb) multivariate analysis of variance (MANOVA) were run to examine differences between contact (penultimate and final) or limb (dominant and non-dominant) for sagittal plane hip, knee and ankle peak angles and moments, and frontal plane knee abduction moments and angles between sexes. Average horizontal GRF was increased on the dominant limb, compared to non-dominant and for the final contact compared to the penultimate contact. Knee abduction angles were increased in females compared to males, while the opposite was true for knee abduction moments. Statistically significant differences were evident, with increases in peak vertical GRF, peak hip flexion angle, peak knee flexion angle, peak knee extensor moment, and peak ankle dorsiflexion angle observed in the penultimate contact compared to final contact. The results indicate the penultimate contact during turns helps reduce loading on the final contact, yet male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction.

Effects of plyometric training on measures of physical fitness in racket sport athletes: a systematic review and meta-analysis

Background

Over the past decade, the popularity of racket sports has surged. Plyometric training (PT) has been the focus of extensive research because of the proven benefits it provides to athletes. However, there is a lack of systematic reviews and meta-analyses specifically evaluating the impact of PT on physical fitness metrics in racket sport athletes. This study aimed to conduct a comprehensive review and analysis of evidence derived from randomized controlled trials (RCTs) to evaluate the effects of PT on measures of physical fitness among racket sports athletes.

Methods

The electronic databases PubMed, Web of Science, SCOPUS, and SPORTDiscus were systematically searched up to June 2023 without placing any restrictions on the publication dates. The PICOS method was adopted to establish the inclusion criteria: (a) healthy athletes who participate in racket sports; (b) a PT program; (c) a control group; (d) assessment of physical fitness components pre- and post-PT; and (e) RCTs. The records' methodological quality was assessed utilizing the Physiotherapy Evidence Database (PEDro) scale. The certainty in the evidence related to each outcome was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessment. A random-effects model was used to calculate effect sizes (ES; Hedges' g) between experimental and control groups.

Results

There were 14 eligible studies of moderate-to-high-quality, involving 746 athletes in total. The results revealed small-to-moderate effects (p < 0.05) of PT on muscle power (ES = 0.46), muscle strength (ES = 0.50), sprint speed (ES = 0.45), change of direction ability (ES = 0.76), and reaction time (ES = 0.67), while no clear evidence was found on balance and flexibility. The training-induced changes in muscle power showed no significant difference (p > 0.05) between youth (ES = 0.72) and adults (ES = 0.40). There were also similar muscle power improvements (ES = 0.36-0.54 vs 0.38-0.56, all p > 0.05) for a length of ≤7 weeks with ≤14 total PT sessions vs >7 weeks with >14 total PT sessions, and ≤2 weekly sessions vs >2 sessions. No adverse effects were reported in the included studies regarding the PT intervention. The certainty of evidence varied from very low to moderate. Conclusions: Our findings demonstrated that PT has positive effects on important indices of physical fitness among athletes participating in racket sports. Future studies are required to clarify the optimal doses and examine interactions among training variables to further promote the physical fitness of this specific population.

Effect of individualised strength and plyometric training on the physical performance of basketball players

The aims of this study were to examine the effects of eight weeks of individualised force-velocity imbalance (F-Vimb) training on physical performance in basketball players and to analyse the differences in physical performance between two periods of time (four to eight weeks) with this training. Thirty male players (age, 22.8 ± 5.68 years; height, 1.87 ± 0.07 m; body mass, 86.3 ± 11.1 kg) were divided into an intervention group (INT, n = 15), who performed an individualised training based on individual F-Vimb; and a control group (CON, n = 15), who underwent a non-individualised training programme; both groups performed two days/week of intervention and the same pre-season basketball training. At baseline, at four weeks, and at eight weeks of intervention, an assessment was performed including countermovement-jumps, unilateral drop jumps, triple hop test, force-velocity profile, sprint and change of direction (COD). At four weeks, the INT showed improvements in sprint and vertical jumping actions (≥3.76%, ES ≥0.44, p ≤ 0.02). At eight weeks, the INT continued to improve vertical jumping actions (p < 0.05) and showed improvements in horizontal jumping (6.80%, ES = 0.45, p < 0.01) and COD (≥2.99%, ES ≥0.96, p < 0.01). A significant reduction in F-Vimb was observed for INT (ES = 0.77, p = 0.01). In contrast, none of these changes were observed in CON. Thus, an individualised F-Vimb training intervention improved physical performance after eight weeks, with changes in sprint and vertical jump after first four weeks. Basketball coaches should optimise the force-velocity profile and improve the performance in sport-related actions as jumping and changing direction.

Mixed Training Programs Applied to Young Soccer Players: Effects on Speed-Power Abilities

We compared the effects of two 4-week strength-power-speed training protocols on physical performance of young soccer players. Twenty-three highly trained under-20 soccer players were randomly allocated to two mixed-training groups: 1) "traditional" (TRAD: n=11), comprising vertically oriented strength-power exercises and linear sprints; or 2) "multidirectional" (MULTI: n=12), combining vertically and horizontally oriented strength-power exercises, linear sprints, and change-of-direction (COD) drills. Squat jump (SJ) and countermovement jump, 2) linear sprint, COD speed, and 3) jump-squat (JS) and hip-thrust (HT) power tests were performed pre- and post-training. Differences were determined using a two-way ANOVA with repeated measures and "target scores" were used to detect real changes in performance. No group-time interactions were found for any of the variables (p>0.05). Significant increases (p<0.05) in 20-m sprint velocity, JS- and HT-power were found in both groups, and in SJ in TRAD. Individual analyses revealed a greater number of meaningful changes in zig-zag velocity in MULTI while most players in TRAD displayed meaningful increases in SJ height. In conclusion, both training protocols resulted in similar adaptations but, at the individual level, it appears that MULTI protocol is superior to improve COD ability while TRAD should be preferred to maximize vertical jumping capabilities during short soccer pre-seasons.

Association between Lower Body Qualities and Change-of-Direction Performance: A Meta-Analysis

The aim of the present study is to determine the associations between lower body muscle strength qualities and change of direction (CoD) performance. Three databases were used to perform a systematic literature search up to September 30, 2022. Based on the studies that met the inclusion criteria, we calculated Pearson's r correlation coefficient to examine the relationships between muscle strength qualities and CoD performance. The quality of the studies included was evaluated by the modified version of the Downs and Black Quality Index Tool. Heterogeneity was determined via the Q statistic and I 2, and Egger's test was used to assess small study bias. The results revealed that lower body maximal strength (pooled: r=- 0.54, dynamic: r=- 0.60, static: r=- 0.41), joint strength (pooled: r=- 0.59, EXT-ecc: r=- 0.63, FLEX-ecc: r=- 0.59), reactive strength (r=- 0.42) and power (pooled: r=- 0.45, jump height: r=- 0.41, jump distance: r=- 0.60, peak power: r=- 0.41) were negatively and moderately related to CoD performance. To conclude, the results highlight that a number of muscle strength qualities are associated with CoD performance and are pertinent to specific phases of a directional change. It should be noted that the conclusions of this study do not establish causality, and further research is needed to better understand their training effects and underlying mechanisms.

Neuromuscular and perceptual-cognitive response to 4v4 small-sided game in youth soccer players

The physical and psychological load of small-sided games (SSGs) can affect players' neuromuscular and cognitive functions. Yet, little is known about the acute performance changes after such a specific exercise in young soccer players and their association with exercise load applied. This study investigates i) the neuromuscular and perceptual-cognitive response to the SSG exercise load, and ii) the relationship between pre- and post-SSG changes in variables of performance and the respective exercise load in youth soccer players. Sixteen participants (13.6 ± 0.5 years) underwent a 30-min SSG 4v4 + GK protocol. Prior to and after the SSG they performed countermovement jump (CMJ), planned and reactive Y-shaped agility tests (PA, RA), and go/no-go task (GNG). Their subjective perception of fatigue was evaluated by visual analog scale. Fatigue induced by SSG (perception of fatigue increased by 41.56%, p = .001, g = 4.15) increased PA time (4.04%, p = .002, g = .97), RA time (6.45%, p = .003, g = 1.16), and number of errors in the response inhibition task (87.1%, p = .023, rc = .57), whilst decreased CMJ height (-6.65%, p = .014, g = .56). These performance deteriorations were not significantly associated with neither internal nor external load variables. However, a less pronounced drop in performance was related to external load variables, i.e., ∆CMJ height and ∆RA time correlated with very high-speed running (rs = .66, p = .006; rs = -.50, p = .022; respectively) and maximal speed (r = .54, p = .032; r = -.52, p = .037; respectively), whilst ∆PA time was associated with high-intensity accelerations (rs = -.76, p = .002). These findings indicate that fatigue induced by SSG affects both planned and reactive agility, decision-making in response inhibition task, and explosive strength in youth soccer players regardless of significant contribution of any robust internal or external load variables. Nonetheless, high-intensity actions within SSG partially compensate for the decrements in their agility performance and explosive strength. The load variables encountered during SSG do not fully reflect youth players' neuromuscular and perceptual-cognitive responses to sport-specific exercise.

Speed Training Practices of Brazilian Olympic Sprint and Jump Coaches: Toward a Deeper Understanding of Their Choices and Insights (Part II)

This is the second article in a three-article collection regarding the plyometric, speed, and resistance training practices of Brazilian Olympic sprint and jump coaches. Here, we list and describe six out of the ten speed training methods most commonly employed by these experts to enhance the sprinting capabilities of their athletes. Maximum speed sprinting, form running, resisted sprinting, overspeed running, uphill and downhill running, and sport-specific movement methods are critically examined with reference to their potential application in different sport contexts. In an era when sprint speed is of critical importance across numerous sports, practitioners can employ the methods outlined here to design efficient training programs for their athletes.

Acute effects of prior conditioning activity on change of direction performance. A systematic review and meta-analysis

We performed a systematic review and meta-analysis on the acute effects of prior conditioning activity (CA) on change of direction (COD) performance. Eligible studies, involving healthy participants undergoing acute CA with at least one measure of COD performance, were analysed across diverse databases. A total of 34 studies were included for systematic review with 19 studies included for the meta-analysis. The intervention condition resulted in significantly faster (Z = 4.39; standard mean difference [SMD] = 0.49; p < 0.05) COD performance compared with the control condition. Both unloaded and light loaded CA resulted in significantly greater (SMD = 0.58-0.59) COD performance compared to the control condition. Moreover, heavy loaded CA demonstrated a significant but small (SMD = 0.24) improvement in COD performance compared to the control condition. Age and study design had no effect on the overall meta-analysis outcomes. Both males and females exhibited similar moderate effects with CA but only males demonstrated significantly greater COD performance compared to control conditions. Our findings indicate that a range of CA protocols can acutely improve COD performance with unloaded and light-loaded CA resulting in the greatest performance enhancements. These findings will assist practitioners with the design and implementation of appropriate acute CA to improve COD performance.

Effects of physical training programs on female tennis players' performance: a systematic review and meta-analysis

Background: Tennis is among the world's most popular and well-studied sports. Physical training has commonly been used as an intervention among athletes. However, a comprehensive review of the literature on the effects of physical training programs on female tennis players' performance is lacking. Therefore, this systematic review and meta-analysis aimed to determine the effects of physical training on performance outcomes in female tennis players. Methods: A comprehensive search was conducted on Web of Science, PubMed, SPORTDicus, Scopus, and CNKI from inception until July 2023 to select relevant articles from the accessible literature. Only controlled trials were included if they examined the effects of physical training on at least one measure of tennis-specific performance in female tennis players. The Cochrane RoB tool was employed to assess the risk of bias. The CERT scale was used to examine the quality of program information. The GRADE approach was adopted to evaluate the overall quality of the evidence. The Comprehensive Meta-Analysis software was used for the meta-analysis. Results: Nine studies were selected for the systematic review and seven for the meta-analysis, totaling 222 individuals. The study's exercise programs lasted 6-36 weeks, with training sessions ranging from 30 to 80 min, conducted one to five times per week. Muscle power (ES = 0.72; p = 0.003), muscle strength (ES = 0.65; p = 0.002), agility (ES = 0.69; p = 0.002), serve velocity (ES = 0.72; p = 0.013), and serve accuracy (ES = 1.14; p = 0.002) demonstrated significant improvement following physical training, while no notable changes in linear sprint speed (ES = 0.63; p = 0.07) were detected. Conclusion: Although research on physical training in sports is diversified, studies on training interventions among female tennis players are scarce. This review found that existing training programs yield some favorable outcomes for female tennis players. However, further research with high methodological quality is warranted on the tailoring of specific training programs for female tennis players. There should be more consistent measuring and reporting of data to facilitate meaningful data pooling for future meta-analyses.

An Optoelectronics-Based Compressive Force Sensor with Scalable Sensitivity

There is an increasing need to accurately measure compressive force for biomedical and industrial applications. However, this need has not been fully addressed, as many sensors are bulky, have high power requirements, and/or are susceptible to electromagnetic interference. This paper presents an optoelectronics-based force sensor that can overcome the limitations of many sensors in the market. The sensor uses a light emitting diode (LED) to transmit visible broad-spectrum light into a photoresistor through an optically clear spacer on top of an elastomeric medium. In the absence of an external force, the light path is mostly blocked by the opaque elastomeric medium. Under a compressive force, the clear spacer compresses the elastomer, moving itself into the light path, and thus increasing the overall light transmission. The amount of light received by the photoresistor is used to quantify compressive force based on elastomer displacement/compression and a priori knowledge of elastomer stiffness. This sensing scheme was tested under eight different configurations: two different sized sensors with four types of elastomers per size (20A neoprene, 30A neoprene, 50A neoprene, and 75A styrene-butadiene rubber (SBR)). All configurations measured force with R² > 0.97, RMSE < 1.9 N, and sensitivity values ranging from 17 to 485 N/V. This sensing scheme provides a low-cost, low-power method for accurate force sensing with a wide force range.

Effects of plyometric training on technical skill performance among athletes: A systematic review and meta-analysis

BACKGROUND

The literature has proven that plyometric training (PT) improves various physical performance outcomes in sports. Even though PT is one of the most often employed strength training methods, a thorough analysis of PT and how it affects technical skill performance in sports needs to be improved.

METHODS

This study aimed to compile and synthesize the existing studies on the effects of PT on healthy athletes' technical skill performance. A comprehensive search of SCOPUS, PubMed, Web of Science Core Collection, and SPORTDiscus databases was performed on 3rd May 2023. PICOS was employed to establish the inclusion criteria: 1) healthy athletes; 2) a PT program; 3) compared a plyometric intervention to an active control group; 4) tested at least one measure of athletes' technical skill performance; and 5) randomized control designs. The methodological quality of each individual study was evaluated using the PEDro scale. The random-effects model was used to compute the meta-analyses. Subgroup analyses were performed (participant age, gender, PT length, session duration, frequency, and number of sessions). Certainty or confidence in the body of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Thirty-two moderate-high-quality studies involving 1078 athletes aged 10-40 years met the inclusion criteria. The PT intervention lasted for 4 to 16 weeks, with one to three exercise sessions per week. Small-to-moderate effect sizes were found for performance of throwing velocity (i.e., handball, baseball, water polo) (ES = 0.78; p < 0.001), kicking velocity and distance (i.e., soccer) (ES = 0.37-0.44; all p < 0.005), and speed dribbling (i.e., handball, basketball, soccer) (ES = 0.85; p = 0.014), while no significant effects on stride rate (i.e., running) were noted (ES = 0.32; p = 0.137). Sub-analyses of moderator factors included 16 data sets. Only training length significantly modulated PT effects on throwing velocity (> 7 weeks, ES = 1.05; ≤ 7 weeks, ES = 0.29; p = 0.011). The level of certainty of the evidence for the meta-analyzed outcomes ranged from low to moderate.

CONCLUSION

Our findings have shown that PT can be effective in enhancing technical skills measures in youth and adult athletes. Sub-group analyses suggest that PT longer (> 7 weeks) lengths appear to be more effective for improving throwing velocity. However, to fully determine the effectiveness of PT in improving sport-specific technical skill outcomes and ultimately enhancing competition performance, further high-quality research covering a wider range of sports is required.

Performance in the Yo-Yo Intermittent Recovery Test May Improve with Repeated Trials: Does Practice Matter?

The Yo-Yo Intermittent Test is frequently used to monitor changes in athletes' performance in response to different interventions. However, the question remains as to whether, and to what extent, retakes of this test would contribute to these changes. This case study sought to determine the magnitude of practice effects, involving test repetition, on performance in the Yo-Yo Intermittent Recovery Test. A recreational soccer player performed four attempts of the Yo-Yo Intermittent Recovery Test-Level 1 (YYIR1) with a week's rest in between. The same participant repeated this test protocol (four attempts of the YYIR1) again after six months. Changes in distance covered, level achieved, maximal oxygen uptake, and heart rate between the first and last attempt were assessed. The smallest worthwhile change (SWC), the coefficient of variation (CV), and the 2CV were calculated to identify a trivial, a possibly meaningful, and a certainly meaningful change in YYIR1 performance. The distance covered in the first set of measurements increased from 1320 m to 1560 m (15.4%), which corresponds to a 4.6% increase in the level achieved (from 16.6 to 17.4). Similarly, the distance covered in the second set of measurements increased from 1280 m to 1560 m (17.9%), which corresponds to a 5.5% increase in the level achieved (from 16.5 to 17.4). The participant's performance changes fell outside of the SWC and the CV, but not the 2CV during both sets of measurements. These improvements in YYIR1 performance may be ascribed to practice with repeated attempts of the test by improving running technique at the turning point and/or by simply increasing the linear speed. This fact should always be kept in mind when interpreting the effects of training. Practitioners should differentiate between practice effects associated with repeated test execution and adaptation induced by conducting sport-specific training.

Plyometric-Jump Training Effects on Physical Fitness and Sport-Specific Performance According to Maturity: A Systematic Review with Meta-analysis

BACKGROUND

Among youth, plyometric-jump training (PJT) may provide a safe, accessible, and time-efficient training method. Less is known on PJT effectiveness according to the maturity status.

OBJECTIVE

This systematic review with meta-analysis set out to analyse the body of peer-reviewed articles assessing the effects of PJT on measures of physical fitness [i.e., maximal dynamic strength; change of direction (COD) speed; linear sprint speed; horizontal and vertical jump performance; reactive strength index] and sport-specific performance (i.e., soccer ball kicking and dribbling velocity) according to the participants' maturity status.

METHODS

Systematic searches were conducted in three electronic databases using the following inclusion criteria: (i) Population: healthy participants aged < 18 years; (ii) Intervention: PJT program including unilateral and/or bilateral jumps; (iii) Comparator: groups of different maturity status with control groups; (iv) Outcomes: at least one measure of physical fitness and/or sport-specific performance before and after PJT; (v) experimental design with an active or passive control group, and two or more maturity groups exposed to the same PJT. The DerSimonian and Laird random-effects models were used to compute the meta-analysis. The methodological quality of the studies was assessed using the PEDro checklist. GRADE was applied to assess certainty of evidence.

RESULTS

From 11,028 initially identified studies across three electronic databases, 11 studies were finally eligible to be meta-analysed (n total = 744; seven studies recruited males; four studies recruited females). Three studies were rated as high quality (6 points), and eight studies were of moderate quality (5 points). Seven studies reported the maturity status using age at peak height velocity (PHV; pre-PHV values up to - 2.3; post-PHV up to 2.5). Another four studies used Tanner staging (from Tanner I to V). The training programmes ranged from 4 to 36 weeks, using 1-3 weekly training sessions. When compared to controls, pre-PHV and post-PHV participants obtained small-to-moderate improvements (ES = 0.35 - 0.80, all p < 0.05) in most outcomes (i.e., sport-specific performance; maximal dynamic strength; linear sprint; horizontal jump; reactive strength index) after PJT. The contrast of pre-PHV with post-PHV youth revealed that PJT was similarly effective in both maturity groups, in most outcome measures except for COD speed (in favour of pre-PHV). PJT induces similar physical fitness and sport-specific performance benefits in males and females, with a minimal exercise dosage of 4 weeks (8 intervention sessions), and 92 weekly jumps. Results of this meta-analysis are based on low study heterogeneity, and low to very low certainty of evidence (GRADE analysis) for all outcomes.

CONCLUSION

Compared to control participants, PJT resulted in improved maximal dynamic strength, linear sprint speed, horizontal jump performance, reactive strength index, and sport-specific performance (i.e., soccer ball kicking and dribbling velocity). These effects seem to occur independently of the maturity status, as both pre-PHV and post-PHV participants achieved similar improvements after PJT interventions for most outcomes. However, several methodological issues (e.g., low sample sizes and the pooling of maturity categories) preclude the attainment of more robust recommendations at the current time. To address this issue, consistency in maturity status reporting strategies must be improved in future studies with the general youth population and youth athletes.

Variable Resistance-An Efficient Method to Generate Muscle Potentiation: A Systematic Review and Meta-Analysis

Variable resistance (VR) is a methodology that has shown good results in developing muscular strength and power. However, no updated information relates to the use of VR as an activation to trigger post-activation performance enhancement (PAPE). The primary objective of this systematic review and meta-analysis was to review and qualitatively describe studies published between 2012 and 2022 that used VR to generate PAPE in muscle power-dominant sports. The secondary objective was to calculate the effect size of the different power outcomes reported in the selected studies. The search was designed following the PRISMA^® guidelines for systematic reviews and meta-analyses and performed in the Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2012 and 2022. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the throwing speed, time in sprint tests, and jump height. The analysis was conducted with a pooled standardized mean difference (SMD) through a Hedges' g test (95% CI). Twenty-two studies were included in the systematic review and ten in the meta-analysis, revealing a trivial effect for throwing speed (SMD = 0.06; CI = 95%: -0.23-0.35; p = 0.69), a small effect for the time in sprint tests (SMD = -0.37; CI = 95%: -0.72--0.02; p = 0.04), and a moderate effect for jump height (SMD = 0.55; CI = 95%: 0.29-0.81; p ˂ 0.0001). All forms of VR used for neuromuscular activation effectively triggered PAPE. Specifically, the results showed that activation with VR generates performance increases in time, in sprint tests and jump height, and a trivial effect in throwing tests (speed and distance).

Association of Strength Performance in Bench Press and Squat with Anthropometric Variables between Resistance-Trained Males and Females

Individual differences in the appropriate percentage of 1-RM for a given repetition range could be a result of variation in anthropometrics and/or sex. Strength endurance is the term used to describe the ability to perform a number of repetitions prior to failure (AMRAP) in sub-maximal lifts and is important in determining the appropriate load for the targeted repetition range. Earlier research investigating the association of AMRAP performance and anthropometric variables was often performed in a sample of pooled sexes or one sex only or by utilizing tests with low ecological validity. As such, this randomized cross-over study investigates the association of anthropometrics with different measures of strength (maximal and relative strength and AMRAP) in the squat and bench press for resistance-trained males (n = 19, 24.3 ± 3.5 years, 182 ± 7.3 cm, 87.1 ± 13.3 kg) and females (n = 17, 22.1 ± 3 years, 166.1 ± 3.7 cm, 65.5 ± 5.6 kg) and whether the association differs between the sexes. Participants were tested for 1-RM strength and AMRAP performance, with 60% of 1-RM in the squat and bench press. Correlational analysis revealed that for all participants, lean mass and body height were associated with 1-RM strength in the squat and bench press (0.66, p ≤ 0.01), while body height was inversely associated with AMRAP performance (r ≤ -0.36, p ≤ 0.02). Females had lower maximal and relative strength with a greater AMRAP performance. In the AMRAP squat, thigh length was inversely associated with performance in males, while fat percentage was inversely associated with performance in females. It was concluded that associations between strength performance and anthropometric variables differed for males and females in fat percentage, lean mass, and thigh length.

Change of Direction Speed in Youth Male Soccer Players: The Predictive Value of Anthropometrics and Biological Maturity

This study aimed to develop the optimal allometric body size/shape and a biological maturity model that predicted the change of direction (CoD) mean speed performance in youth male soccer players. One-hundred and fifteen youth soccer players (age: 12.4 [1.3] y) participated in this study. The 505 test was used to assess CoD mean speed performance. Anthropometric measurements comprised body height (cm), sitting height (cm), body mass (kg), fat mass (kg), lower limb length (cm), thigh length (cm), leg length (cm), foot length (cm), thigh girth (cm), and calf girth (cm). The maturity status was determined based on the maturity offset method. To identify size/shape and maturity characteristics associated with CoD speed performance, we computed a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 505 CoD mean speed performance and the different anthropometric characteristics in youth soccer players estimated that fat mass (P < .001), sitting height (P = .02), and maturity offset (P = .004) are the key predictors. More specifically, youths who are more mature and have a lower fat mass and a shorter trunk length, are likely to achieve a better CoD mean speed performance. These findings highlight the relevance of considering anthropometric and maturity characteristics in youth soccer players to support talent identification.

Performance Outcomes Following Isoinertial or Machine-Based Training Interventions in Female Junior Tennis Players

PURPOSE

To evaluate changes in physical performance indicators after executing a flywheel or machine-based neuromuscular training program in young female tennis players.

METHODS

Twenty-four players were divided into a machine-based  group (MG), flywheel  group (FG), and control group. Countermovement jump (CMJ), sprint time (5, 10, and 15 m), change-of-direction (COD) performance (right and left), medicine-ball throws (overhead, forehand, and backhand), and serve velocity were included as tests at baseline, week 4, and week 8.

RESULTS

Both MG and FG largely improved from baseline to weeks 4 and 8 of training in CMJ (11.6, 10.6%; effect size [ES] = 1.24, 1.95). Also, sprint time 5 m and 10 m, COD performance-right, and COD performance-left improved moderately to very largely at week 4 in MG (-5.0% to -6.2%; ES = -1.79 to -4.19) and FG (-2.9% to -5.1%; ES = -1.13 to -1.64), respectively. Regarding medicine-ball throw, only FG improved moderately to very largely from weeks 4 to 8 in overhead (9.3%; ES = 1.46), forehand (8.0%; ES = 1.08), and backhand (6.1%; ES = 1.15). Serve velocity improved moderately from weeks 4 to 8 in MG (5.8%; ES = 0.87).

CONCLUSIONS

Four weeks of the tested programs seem sufficient to improve physical determinants in young female participants. Greater improvements in CMJ and medicine-ball throw following flywheel neuromuscular training indicate the importance of including exercises that emphasize the stretch-shortening cycle and involve the entire kinetic chain. Performing the same intervention with no load adjustments may stall or even decrease performance in some parameters from weeks 4 to 8.

Effects of Plyometric Training with Resistance Bands on Neuromuscular Characteristics in Junior Tennis Players

The purpose of this study is to investigate the effect of 6 weeks (conducted twice per week for a total of 12 sessions) of plyometric training with resistance bands on different neuromuscular characteristics among the sample of junior tennis players. Thirty junior tennis players between the ages of 12 and 14 years (age 13.5 ± 1.8 years; weight 51.3 ± 12.5 kg; height 162.7 ± 12.6 cm) were allocated to either the control group (standard in-season regimen) (CG; n = 15) or the experimental group, which received additional plyometric training with resistance bands (TG; n = 15). Pre- and post-tests included: anthropometric measures; 20 m sprint time (with 5, 10, and 20 m splits), squat jump (SQ Jump); vertical countermovement jump (CMJ); vertical countermovement jump with arm swing (CMJ_free arms); single leg (left) countermovement jump (CMJ_L); single leg (right) countermovement jump (CMJ_R); standing long jump (L_Jump); single leg (left) triple jump (SLTH-L); single leg (right) triple jump (SLTH-R); generic change of direction speed (CODS) (20Y test and T-test); reactive agility test (WS-S). After the training intervention, the TG showed significant (“p < 0.05”) improvements in CMJ (F = 7.90, p = 0.01), CMJ_L (F = 5.30, p = 0.03), CMJ_R (F = 11.45, p = 0.00), and SLTH-L (F = 4.49, p = 0.04) tests. No significant changes were observed in the CG after the training intervention. Our findings provide useful information for coaches to create a wide range of tennis-specific situations to develop a proper performance, especially for their player’s neuromuscular fitness.

Training to Improve Pro-Agility Performance: A Systematic Review

Effective directional change in sport is imperative to success in key game situations. Change of direction (COD) ability is underpinned by various athletic qualities which can be developed through specific and non-specific training methods. This review examined the effect of specific and non-specific training methods on pro-agility performance, by analysing the intervention type and resulting magnitude of training effects on pro-agility shuttle performance. A total of 20 studies were included for review. Data from 638 subjects and 29 intervention groups involving seven different training methods were extracted and analysed in relation to training method classification and primary outcome measures. Interventions involving sprint training, plyometric training, resistance training, and combined resistance, plyometric, and sprint training were found to produce statistically significant positive change on pro-agility performance per session (p < 0.05). Sprint training (0.108 ES), plyometric training (0.092 ES), resistance training (0.087 ES), and combined resistance, plyometric, and sprint training (0.078 ES) methods were found to have the highest per session training effect. While total time is the typical unit of measure for this test, different types of training may lead to preferential improvements in either acceleration, deceleration, or COD phases of the pro-agility shuttle. Specifically, resisted or inclined sprinting may develop the linear acceleration phases, unilateral resistance training may promote increased strength to overcome the imposed forces during the deceleration and COD phases, multiplanar plyometrics can help enhance stretch-shortening cycle capabilities across different force vectors, and a combination of two or more of these methods may enable simultaneous development of each of these qualities.

Development and trainability of agility in youth: A systematic scoping review

Background

Agility is acknowledged as a crucial factor of performance in various open skill sports in both adult and youth athletes. However, despite its significance for sports performance the development and the trainability of agility are under-researched within the pediatric literature. A systematic scoping review was considered most appropriate to provide researchers and practitioners with an overview of the current body of literature approaching agility in youth.

Objectives

The objectives of this scoping review were to map the extent, range, and nature of existing evidence regarding trainability and "natural" development of agility and to summarize corresponding study results.

Methods

The scoping review protocol was pre-registered at Open Science Framework. Systematic searches were conducted using the databases PubMed, Scopus, ProQuest, Web of Science, SURF, and SPONET to identify sources covering agility in youth. Among other inclusion criteria, only references applying unplanned agility concepts were included.

Results

Ultimately, 41 reports were included comprising 23 observational studies, 14 experimental studies, and 4 references of secondary research. A total of 3,087 subjects were assessed in the included studies. Subject groups were predominantly male, above 10 years of age, and soccer athletes. Outcomes of observational studies indicate an effect of age and maturation on agility performance resulting in a non-linear "natural" development of agility. Furthermore, relationships between contributing perceptual-cognitive factors and agility performance tend to increase with progressing age, whereas relationships between physical factors and agility performance diminish. Evidence of training studies suggests that agility is trainable in youth, albeit with various underlying mechanisms.

Conclusions

This systematic scoping review is the first mapping of the body of literature about agility in youth. It outlines the current evidence base, reveals research gaps, and points out future directions to support researchers and practitioners in this field. Although, increasing research activity in this field is discernible, agility research in youth is still in its infancy. Considering the significance of agility for sports performance, future research is postulated to design evidence-based strategies for long-term agility development in young athletes.

Leg dominance and performance in change of directions tests in young soccer players

The present study aimed to examine the influence of leg dominance on the change of direction (COD) performance. In this study participated 94 healthy young highly trained male soccer players belonging from two categories (n = 27 vs. n = 67; 14.81 ± 0.40 vs. 16.64 ± 1.25 years of age; 170.61 ± 5.61 vs. 173.73 ± 7.19 cm of height; 64.74 ± 8.44 vs. 66.70 ± 7.95 kg of weight, for U16 and U18, respectively). Fitness assessments were performed two times in a period of three months, and included: (1) anthropometry measures, (2) 30–15 IFT, (3) 10-m sprint test, (4) 505-COD test, 90° COD test and cross-over hop test. A paired sample t-test was performed to evaluate the asymmetries at the intragroup level in each of the COD’s tests. A symmetry index was used to analyse the asymmetries between categories, and an independent sample t-test was used to compare the variability between the two categories in each of the three tests performed. The effect size was also evaluated. Analysis demonstrated that evidence a trend for a better performance with the preferred leg in the cross-over hop and 505-COD tests, and with the non-dominant leg in the 90° COD. However, in the intragroup analysis, only the 505-COD test registered differences, and no differences were notice din the intergroup comparison. Only in the 505-COD test the percentage of variability (CV) was statistically significant (7.03 ± 4.18% vs. 4.03 ± 2.02% from U16 and U18, respectively). In sum, bilateral differences were noticed in the intragroup comparison, although only in 505-COD test the leg dominance showed to influence performance. In the intergroup analysis any difference was noticed between age categories.

Within Session Exercise Sequencing During Programming for Complex Training: Historical Perspectives, Terminology, and Training Considerations

The primary aim of this narrative review was to outline the historical genesis of resistance training strategies that incorporate high-load, low-velocity exercises and low-load, high-velocity exercises in the same training session allowing for different "exercise sequences" to be simultaneously implemented. Discrepancies between scientific works and the terminology used within contemporary sport science publications are identified. Upon review of the literature, we propose "complex training" to be considered an umbrella term with 4 different implementations, generally used to indicate a method in which movement velocity or load is altered between sets and/or exercises within the same session with the aim of improving slow and fast force expression. We propose the following terminology for said implementations: contrast training-exercise sequence with alternating high-load and low-load (higher-velocity) exercises in a set-by-set fashion within the same session (corresponding with 'contrast pairs' and 'intra-contrast rest'); descending training-several sets of high-load (e.g., back squat) exercises completed before the execution of several sets of low-load, higher-velocity (e.g., vertical jump) exercises within the same session; ascending training-several sets of low-load, higher-velocity exercises completed before several sets of high-load exercises within the same session; and French contrast training-subset of contrast training in which a series of exercises are performed in sequence within a single session: heavy compound exercise, plyometric exercise, light-to-moderate load compound exercise that maximises movement speed (i.e., external power), and a plyometric exercise (often assisted). Finally, practical applications and training considerations are presented.

Effects of small-sided games and running-based high-intensity interval training on body composition and physical fitness in under-19 female soccer players

Background

The aim of this study was to compare the effects of small-sided games (SSGs) and running-based high-intensity interval training (HIIT) on the body composition and physical fitness of youth female soccer players.

Methods

This study followed a randomized parallel study design. Twenty-four female soccer players (age: 18.63 ± 2.36 years) were randomly allocated to two training groups (SSG, n = 12; and HIIT, n = 12). The training intervention had a duration of eight weeks, consisting of three training sessions per week. Players were assessed twice (pre- and post-intervention) for anthropometrics, vertical (countermovement jumps, CMJ; and drop jumps, DJ) and horizontal jumping (single, triple and crossover hop), sprinting (10- and 30-m), change-of-direction (COD), COD deficit and final velocity at 30–15 Intermittent Fitness Test (V_IFT). A covariance analysis (ANCOVA) was used to determine differences between the groups in the effect on post-intervention by controlling for covariates (pre-intervention). The within-group analysis (time) was performed using a paired t-test, while the between-group analysis per assessment moment was performed using an independent t-test.

Results

The between-group analysis with ANCOVA revealed that there are no significant differences between the SSG and HIIT groups in the post-intervention for any outcome (p > 0.05). The within-group analysis revealed significant improvements in both the SSG and HIIT groups in CMJ (p < 0.05), single, triple and crossover hops (p < 0.05), RSI DJ 30-cm and RSI DJ 40-cm (p < 0.05), VIFT (p < 0.05) and COD (p < 0.05).

Conclusions

SSG and HIIT are both effective for improving vertical and horizontal jumping ability, change-of-direction, and aerobic capacity status measured at a progressive and intermittent multistage test in youth soccer players.

Biomechanical and Neuromuscular Performance Requirements of Horizontal Deceleration: A Review with Implications for Random Intermittent Multi-Directional Sports

Rapid horizontal accelerations and decelerations are crucial events enabling the changes of velocity and direction integral to sports involving random intermittent multi-directional movements. However, relative to horizontal acceleration, there have been considerably fewer scientific investigations into the biomechanical and neuromuscular demands of horizontal deceleration and the qualities underpinning horizontal deceleration performance. Accordingly, the aims of this review article are to: (1) conduct an evidence-based review of the biomechanical demands of horizontal deceleration and (2) identify biomechanical and neuromuscular performance determinants of horizontal deceleration, with the aim of outlining relevant performance implications for random intermittent multi-directional sports. We highlight that horizontal decelerations have a unique ground reaction force profile, characterised by high-impact peak forces and loading rates. The highest magnitude of these forces occurs during the early stance phase (< 50 ms) and is shown to be up to 2.7 times greater than those seen during the first steps of a maximal horizontal acceleration. As such, inability for either limb to tolerate these forces may result in a diminished ability to brake, subsequently reducing deceleration capacity, and increasing vulnerability to excessive forces that could heighten injury risk and severity of muscle damage. Two factors are highlighted as especially important for enhancing horizontal deceleration ability: (1) braking force control and (2) braking force attenuation. Whilst various eccentric strength qualities have been reported to be important for achieving these purposes, the potential importance of concentric, isometric and reactive strength, in addition to an enhanced technical ability to apply braking force is also highlighted. Last, the review provides recommended research directions to enhance future understanding of horizontal deceleration ability.

Associations between lower limb eccentric muscle capability and change of direction speed in basketball and tennis players

Background

The ability to perform a quick and rapid change of direction (CoD) is an important determinant of success in a variety of sports. Previous studies have already highlighted that eccentric strength is a dominant predictor of CoD. However, these studies evaluated eccentric strength through a limited number of outcome measures and used small sample sizes.

Methods

A total of 196 athletes participated in the study. The aim of our study was to investigate: (1) the correlation between eccentric outcome measures derived from different tests (Nordic hamstring exercise (NHE), countermovement jump (CMJ) and flywheel (FW) squats), (2) the association between eccentric outcome measures and CoD 90°, CoD 180°; and (3) proportion of explained variance in CoD performance.

Results

Very large associations (r = 0.783, p < 0.001) were observed between peak torque during NHE (NHE_PT) and force impulse during the eccentric phase of CMJ (CMJ_FI). Small to moderate correlations were calculated between peak eccentric force in flywheel squats and peak eccentric force in CMJ (r = 0.220-035, p < 0002). All eccentric CMJ outcome measures and NHE_PT were reported as moderate negative associations with both CoD tests. Eccentric measures explained 25.1% of the variance in CoD 90° (CMJ_PF, NHE_PT, F_0.125 -peak eccentric force during FW squats with 0.125 kg m² load), while the same outcome measures explained 37.4% of the variance for CoD 180°.

Conclusion

Our results suggest that different measures of eccentric strength specifically contribute to CoD performance. Therefore, for successful CoD performance, different aspects of eccentric strength training should be considered in testing and training (maximal eccentric strength, eccentric-concentric actions with fast execution).

Block-sequence of plyometric and balance training is superior to the alternating-sequence for enhancing motor function in children with hemiplegic cerebral palsy: A comparative randomized clinical trial

BACKGROUND: Postural control deficits are prevalent in children with hemiplegic cerebral palsy (CwHCP). Therefore, the best rehabilitative strategies for remediating these deficits are warranted, which could then enhance function. OBJECTIVE: To examine effects of a block versus an alternating sequence of balance training (BT) and plyometric training (PT) on postural control in CwHCP. METHODS: Forty-eight CwHCP (812 years) were randomized to a block or an alternating BT/PT training. The block BT/PT group (n= 24) received a sixweek BT followed by a sixweek PT, twice/week over 12 consecutive weeks. The alternating BT/PT group (n= 24) received an interchanging sequence of BT and PT changed every two weeks for 12 weeks. Postural control [center-of-pressure reaction time (RT), movement velocity (MV), maximum excursion (ME), end-point excursion (EE), and directional control (DC)], functional balance (indicated by pediatric balance scale; PBS), and balance/risk-of-falls during walking (denoted by dynamic gait index; DGI) were assessed before and after training. RESULTS: The block BT/PT group showed greater enhancements in postural control variables [RT (P= 0.004), MV (P= 0.028), ME (P= 0.002), EE (P= 0.003), and DC (P= 0.012)] and functional balance (P= 0.006), and lesser risk-of-falls during walking (P= 0.018) when compared to the alternating BT/PT group. CONCLUSION: The block BT/PT sequence is more effective to enhance postural control than the alternating sequence in CwHCP.

Guidelines for performing systematic reviews in sports science

Most of the reviews carried out in sports science have used the general items suggested by Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). Due to the specific requirements of each knowledge area, several modifications of the PRISMA are necessary to optimize the process of the systematic reviews and, in consequence, the quality of the conclusions provided in this type of study. Therefore, this work aimed to adapt PRISMA to provide specific guidelines to carry out systematic reviews in sports science. The methodology criteria (search strategy, databases, and eligibility) and the results section (flow diagrams and study contents) were adapted based on previous studies, and several new considerations were added to design the new guidelines. We compiled 28 items suggested by sports science researchers and included two new items: (i) population/problem (i.e., age, level, and country) and (ii) the entire training process, which is monitored and compared between groups (e.g., total training load). To maximize the benefit of this document, we encourage people to read it in conjunction with the PRISMA statement. The main differences between PRISMA and the PRISMA adapted to sports science were related to registration, search strategy, flow diagrams, and results. Application of the new guidelines could improve the information provided to readers and make it easier to generalize and compare the results in sports science.

Effects of Six Weeks of Flywheel Single-Leg Romanian Deadlift Training on Speed, Jumping and Change of Direction Performance

Several studies have confirmed the efficacy of flywheel training, mainly in the bilateral half-squat exercise. The aim of the present study was to analyze the effects of single-leg Romanian deadlift flywheel training on speed, jumping and change of direction performance. Seventeen young healthy males underwent two periods of 3-week training based on two weekly sessions of 3 sets × 7 repetitions or 4 sets × 7 repetitions of single-leg Romanian deadlifts (0.037 kg/m² moment inertia) with their dominant and non-dominant leg. After the first three weeks of the program, the CMJ, the 10 m, 30 m and total sprint times, as well as the COD-90 test, presented likely substantial beneficial effects and a small decrease in the relationship between the sprint and COD-90 test performance. After the second period of the three-week training, likely detrimental effects were observed in some of the change of direction conditions and an increase in the relationship between the sprint and the COD-180 performance. It could be hypothesized that most of the flywheel training effects reported in the traditional protocols lasting a minimum of 5–6 weeks would occur in the first weeks of training.

Combining small-sided soccer games and running-based methods: A systematic review

Small-sided games (SSGs) are often used in soccer to produce acute physiological and physical responses, while a tactical/technical stimulus is also employed. However, due to some limitations of SSGs, researchers have been testing this method combined with running-based training methods. This systematic review was conducted to assess the effects of combined SSG and running-based methods on soccer players' acute responses and adaptations after training interventions. A systematic review of Web of Science, PubMed, Cochrane Library, Scopus, and SPORTDiscus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The database search initially identified 782 titles. From those, five articles were deemed eligible for the systematic review. The five included studies presented data from training load, reporting inconsistent greater values in combined SSG and running-based methods when compared to SSG-only formats. Considering the adaptations, studies comparing combined SSG and running-based methods with SSG-only methods revealed inconsistent differences in terms of the effects on aerobic performance and sprinting. Combining SSG and running-based methods can increase the acute mechanical load and high-intense running stimuli in players when compared to interventions that use only SSGs. However, the adaptations promoted by both methods are similar, and the differences are unclear. The order of combination (SSG and running-based method) does not seem to impact players' adaptations; however, the frequency of sessions did have a meaningful impact.

The Effects of Exercise Order on the Psychophysiological Responses, Physical and Technical Performances of Young Soccer Players: Combined Small-Sided Games and High-Intensity Interval Training

This study aimed to compare the order effects of combined small-sided games (SSGs) and high-intensity interval training (HIIT) on the psychophysiological responses and physical and technical performances of young soccer players. Twenty-four soccer players (aged 14.63 ± 0.71 years) were randomly divided into SSGs + HIIT (n = 12) and HIIT + SSGs (n = 12) for 6 weeks. The SSGs consisted of two 4-16 min rounds of 2, 3, and four-a-side games with 2 min of passive resting, whereas the HIIT consisted of 6-10 min of high-intensity runs at varying intensities (from 90 to 100%). Pre-test and post-test elements included a 5-30 m sprint test, countermovement jump test, zigzag agility test with the ball and without the ball, repeated sprint ability test, speed dribbling ability test, three-corner run test, and Yo-Yo Intermittent Recovery Test level 1. Both combined training interventions produced similar improvements in physical performance and technical responses (p ≥ 0.05, d values ranging from 0.40 to 1.10). However, the combined HIIT + SSGs training produced meaningfully lower perceived exertion (p = 0.00, d = 2.98) and greater physical enjoyment (p = 0.00, d = 4.28) compared with the SSGs + HIIT intervention. Furthermore, the SSGs + HIIT group showed a higher training load than those from the HIIT + SSGs group for all weeks (p ≤ 0.05, d values ranging from 1.36 to 2.05). The present study's results might be used by coaches and practitioners to design training programmes for youth soccer players.

The Relationship Between Reactive Agility and Change of Direction Speed in Professional Female Basketball and Handball Players

Assessing the physical ability of players to perform change of direction and the cognitive and motor abilities revealed in reactive agility (RA) is necessary to understand the physical requirements and capabilities of professional players in handball and basketball. The main aim of this study was to determine the differences between professional female basketball and handball players in terms of anthropometric features, change of direction speed (CODS), and the RA task. Moreover, the relationships among anthropometric features, agility, and parameters of perception were determined. Two scenarios of the Five-Time Shuttle Run to Gates test (planned and unplanned) were used to evaluate the CODS and RA. The response time (RT) was also measured in the unplanned scenario. Additionally, the index of reactivity (REAC-INDEX) was specified as the difference between the RA test result and the measurement of CODS. There was a significant difference found in terms of body height, with basketball players being taller than handball players (p = 0.032). Professional female handball players achieved better results than professional female basketball players with regard to RA tasks (p = 0.01) and CODS (p = 0.041). Significant simple correlations between each anthropometric feature (body height, body mass) and values for CODS and RA were observed (r = 0.49-0.53). Applying partial correlation allowed for the assessment of actual relationships among CODS, RA, RT, and REAC-INDEX, without a confounding variable. Detaching the anthropometric parameters from the rest of the relationships resulted in maintenance or changes in r-values and an increased significance in the relationships between each pair: RA vs. RT, RA vs. REAC-INDEX, and RT vs. REAC-INDEX. The strongest associations were related to RT vs. REAC-INDEX (r = 0.97 at detaching body height or body mass, p < 0.001) and CODS vs. RA (r = 0.66 at detaching body height and r = -0.67 at detaching body mass, p < 0.001). It is recommended to use partial correlations in subsequent studies, as simple correlations are not reliable and may not reveal the apparent relationships between the variables. In addition, when determining the CODS and RA, it is suggested to take anthropometric and perception variables into account, such as reaction time or REAC-INDEX.

Association of Performance in Strength and Plyometric Tests with Change of Direction Performance in Young Female Team-Sport Athletes

The change of direction (COD) ability is a task-specific skill dependent on different factors such as the degree of the turn, which has led to differentiating CODs as more force- (>90°) or velocity-oriented (<90°). Considering force and velocity requirements is of importance when designing sport-specific training programs for enhancing COD performance. Thus, 25 female handball and soccer players participated in this study, which investigated the association between three different strength and plyometric exercises and force- and velocity-oriented COD performance. By utilizing the median split analysis, the participants were further divided into a fast (n = 8) and a slow (n = 8) COD group, to investigate differences in step kinematics between fast and slow performers. The correlational analysis revealed that the bilateral back squat and unilateral quarter squat were significantly associated with several force- and velocity-oriented COD performance (r = -0.46 to -0.64), while the association between plyometric and COD performance was limited (r < 0.44). The fast COD group revealed higher levels of strength, jump height, peak velocities, higher step frequencies, shorter ground contact times, and greater acceleration and braking power (d > 1.29, p < 0.03). It was concluded that the observed correlation between strength and COD performance might be due to stronger athletes being able to produce more workload in a shorter time, which was supported by the step kinematics.

A systematic review of intervention programs that produced changes in speed and explosive strength in youth footballers

A soccer player should possess a reasonable level of different skills and abilities, so the playing position, level of training, style of play, physical and physiological demands can influence his performance. The objective was to identify the intervention programs that have been applied in search of generating positive effects on explosive strength and speed in young soccer players, as well as to identify the percentage of improvement among soccer players. A bibliographic study of systematic review was carried out. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, bibliographic searches were performed in the PubMed database. The following descriptors were used: Explosive Strength, soccer players, jump performance, CMJ, SJ, VJ, Plyometrics, power, speed, sprint, kicking speed, change of direction speed, soccer player, football and training, intervention. Articles were included only if they were original articles, studied populations of young soccer players and showed an intervention program related to explosive strength and speed. Six studies were identified that applied intervention programs to look for changes in speed and explosive strength in young soccer players. In the 5m speed tests, significant changes were observed, improving from (0.26 to 0.53m/s), 10m speed (0.07 to 0.27m/s), 20m speed (0.08 to 1.92m/s) and 40m speed (0.25 to 0.62m/s). In explosive strength, performance in the test squat jump SJ (4.1 to 8.6cm), countermovement jump CMJ (1.0 to 8.8cm), horizontal jump HJ (12.17 to 24.4cm) and vertical jump VJ (5.0 to 11.0cm). Speed and explosive strength are relevant components of athletic performance and can be improved through training programs that include 20 to 40min sessions, training two to five times per week over a period of approximately 6 to 9 weeks.

Change of Direction Speed and Technique Modification Training Improves 180° Turning Performance, Kinetics, and Kinematics

This study aimed to examine the effects of change of direction (COD) speed and technique modification training on 180° turning performance (completion time, ground contact time [GCT], and exit velocity), kinetics, and kinematics. A non-randomised 6 week intervention study was administered. Thirteen male multidirectional sport athletes formed the intervention group (IG), participating in two COD speed and technique modification sessions per week. A total of 12 male multidirectional sport athletes formed the control group (CG). All subjects performed six modified 505 trials, whereby pre-to-post-intervention biomechanical changes were evaluated using three-dimensional motion analysis. Two-way mixed analysis of variances revealed significant interaction effects (group × time) for completion time, mean horizontal propulsive force (HPF), horizontal to vertical mean braking and propulsive force ratios for the penultimate (PFC) and final foot contact (FFC), FFC peak knee flexion and PFC hip flexion angle (p ≤ 0.040, η² = 0.170–0.417). The IG displayed small to large improvements post-intervention in these aforementioned variables (p ≤ 0.058, g = 0.49–1.21). Turning performance improvements were largely to very largely (p ≤ 0.062, r or ρ = 0.527–0.851) associated with increased mean HPF, more horizontally orientated FFC propulsive force and PFC braking force, and greater pelvic rotation, PFC hip flexion, and PFC velocity reductions. COD speed and technique modification is a simple, effective training strategy that enhances turning performance.

Effects of Plyometric Jump Training on Repeated Sprint Ability in Athletes: A Systematic Review and Meta-Analysis

BACKGROUND

There is a growing body of research examining the effects of plyometric jump training (PJT) on repeated sprint ability (RSA) in athletes. However, available studies produced conflicting findings and the literature has not yet been systematically reviewed. Therefore, the effects of PJT on RSA indices remain unclear.

OBJECTIVE

To explore the effects of PJT on RSA in athletes.

METHODS

Searches for this review were conducted in four databases. We included studies that satisfied the following criteria: (1) examined the effects of a PJT exercise intervention on measures of RSA; (2) included athletes as study participants, with no restriction for sport practiced, age or sex; and (3) included a control group. The random-effects model was used for the meta-analyses. The methodological quality of the included studies was assessed using the PEDro checklist.

RESULTS

From 6367 search records initially identified, 13 studies with a total of 16 training groups (n = 198) and 13 control groups (n = 158) were eligible for meta-analysis. There was a significant effect of PJT on RSA best sprint (ES = 0.75; p = 0.002) and RSA mean sprint (ES = 0.36; p = 0.045) performance. We did not find a significant difference between control and PJT for RSA fatigue resistance (ES = 0.16; p = 0.401). The included studies were classified as being of "moderate" or "high" methodological quality. Among the 13 included studies, none reported injury or any other adverse events.

CONCLUSION

PJT improves RSA best and mean performance in athletes, while there were no significant differences between control and PJT for RSA fatigue resistance. Improvements in RSA in response to PJT are likely due to neuro-mechanical factors (e.g., strength, muscle activation and coordination) that affect actual sprint performance rather than the ability to recover between sprinting efforts.

Biomechanical Effects of a 6-Week Change of Direction Speed and Technique Modification Intervention: Implications for Change of Direction Side step Performance

ABSTRACT

Dos'Santos, T, Thomas, C, Comfort, P, and Jones, PA. Biomechanical effects of a 6-week change of direction speed and technique modification intervention: implications for change of direction side step performance. J Strength Cond Res XX(X): 000-000, 2020-The aim of this study was to evaluate the biomechanical effects of change of direction (COD) speed and technique modification training on COD performance (completion time, ground contact time [GCT], and exit velocity) during 45° (CUT45) and 90° (CUT90) side step cutting. A nonrandomized, controlled 6-week intervention study was administrated. Fifteen male, multidirectional, sport athletes (age, 23.5 ± 5.2 years; height, 1.80 ± 0.05 m; mass, 81.6 ± 11.4 kg) formed the intervention group (IG) who participated in two 30-minute COD speed and technique modification sessions per week, whereas 12 male, multidirectional, sport athletes (age, 22.2 ± 5.0 years; height, 1.76 ± 0.08 m; mass, 72.7 ± 12.4 kg) formed the control group (CG) and continued their normal training. All subjects performed 6 trials of the CUT45 and CUT90 task whereby pre-to-post intervention changes in lower-limb and trunk kinetics and kinematics were evaluated using 3-dimensional motion and ground reaction force analyses. Two-way mixed analysis of variances revealed significant main effects for time (pre-to-post changes) for CUT45 completion time, exit velocity, and CUT90 completion time (p ≤ 0.045; η2 = 0.152-0.539), and significant interaction effects of time and group were observed for CUT45 completion time, GCT, exit velocity, and CUT90 completion time (p ≤ 0.010; η2 = 0.239-0.483), with the IG displaying superior performance postintervention compared with the CG (p ≤ 0.109; g = 0.83-1.35). Improvements in cutting performance were moderately to very largely associated (p ≤ 0.078; r or ρ = 0.469-0.846) with increased velocity profiles, increased propulsive forces over shorter GCTs, and decreased knee flexion. Change of direction speed and technique modification is a simple, effective training method requiring minimal equipment that can enhance COD performance, which practitioners should consider incorporating into their pitch- or court-based training programs.

Small-sided games: An umbrella review of systematic reviews and meta-analyses

Objective

This umbrella review was conducted to summarize the evidence and qualify the methodological quality of SR and SRMA published on small-sided games in team ball sports.

Methods

A systematic review of Web of Science, PubMed, Cochrane Library, Scopus, and SPORTDiscus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

From the 176 studies initially identified, 12 (eight SR and four SRMA) were fully reviewed, and their outcome measures were extracted and analyzed. Methodological quality (with the use of AMSTAR-2) revealed that seven reviews had low quality and five had critically low quality. Two major types of effects of SSGs were observed: (i) short-term acute effects and (ii) long-term adaptations. Four broad dimensions of analysis were found: (i) physiological demands (internal load); (ii) physical demands (external load) or fitness status; (iii) technical actions; and (iv) tactical behavior and collective organization. The psychological domain was reduced to an analysis of enjoyment. The main findings from this umbrella review revealed that SSGs present positive effects in improving aerobic capacity and tactical/technical behaviors, while neuromuscular adaptations present more heterogeneous findings. Factors such as sex, age group, expertise, skill level, or fitness status are also determinants of some acute effects and adaptations.

Conclusion

The current umbrella review allowed to identify that most of the systematic review and meta-analysis conducted in SSGs presents low methodological quality considering the standards. Most of the systematic reviews included in this umbrella revealed that task constraints significantly change the acute responses in exercise, while SSGs are effective in improving aerobic capacity. Future original studies in this topic should improve the methodological quality and improve the experimental study designs for assessing changes in tactical/technical skills.

Physical fitness changes among amateur soccer players: effects of the pre-season period

Study aim: To assess changes in physical fitness of amateur soccer players after a pre-season training period and baseline fitness dependencies.

Material and methods: Twenty-one amateur soccer players were assessed during the pre-season. The following physical variables were assessed before and after a two-month pre-season training period: (i) cardiorespiratory fitness, (ii) strength and power, and (iii) change of direction (COD).

Results: Significant decreases were found for countermovement jump (CMJ) (p < 0.001; d = 1.161), drop jump (DJ) (p = 0.014; d = 0.958), and horizontal jump (HJ) (p = 0.042; d = 0.640), while no significant changes were found for the overall variables from the beginning to the end of pre-season. Fit players revealed significant decreases for CMJ (p = 0.002; d = –2.495), DJ (p = 0.004; d = –1.760), HJ (p = 0.028; d = –1.005), COD deficit (p = 0.034; d = 1.013), and maximal aerobic speed (MAS) (p = 0.026; d = –4.053). No significant changes were found for unfit players.

Conclusions: Amateur soccer coaches should consider assessing physical qualities at the beginning of pre-season and use the free-of-charge monitoring tools such as session-rate of perceived exertion (s-RPE) during the training process.

The acute effect of wearable resistance load and placement upon change of direction performance in soccer players

The aim of the study was to examine the acute effect of different lower limb wearable resistance on placement (shank vs thigh) and various loads (1-5% of body mass) upon change of direction (COD) ability. Twelve male soccer players (age: 23.3 ± 2.5 years; height: 179.2 ± 7.4 cm; body mass: 78.3 ± 7.1 kg) performed a change of direction test with different additional loads fixed on either the shank or thigh. Measurement consisted of total time, 90° and 45° split times. large effects of the different wearable resistance placement (p<0.05) and load (p<0.001) were found for total and split change of direction time performance. Change of direction times were higher with shank loading compared with thigh loading. It was concluded that lower limb wearable resistance loading with different loads had an acute effect upon change of direction performance in male soccer players. Furthermore, that distal placement (shank vs thigh) with similar body mass load had a larger effect upon COD performance.

Effects of Strength vs. Plyometric Training on Change of Direction Performance in Experienced Soccer Players

The purpose of this study was to compare how 6 weeks of strength- vs. plyometric training, which were matched upon direction of motion and workload, influences change of direction (COD) performance. Twenty-one experienced male soccer players (age: 22.2 ± 2.7) were pair-matched into a strength- (n = 10) and a plyometric (n = 11) training group. CODs of 45°, 90°, 135° and 180° performed from either a 4 m or 20 m approach distance were compared before and after intervention. Results showed no significant difference between groups. Significant effects were only found within the plyometric training group (−3.2% to −4.6%) in 90°, 135° and 180° CODs from 4 m and a 180° COD from a 20 m approach distance. Individual changes in COD performances showed that with the 4 m approach at least 55% and 81% of the strength and plyometric training group, respectively, improved COD performance, while with the 20 m approach at least 66% of both groups improved performance. This study showed that the plyometric training program can improve most CODs, with angles over 90°, although this is dependent on the distance approaching the COD. Considering the limited time of implementing physical conditioning, in addition to regular soccer practice in most soccer environments, the current plyometric training program can be advantageous in improving CODs at maximal intensity.

Association of strength and plyometric exercises with change of direction performances

The change of direction (COD) ability is an important task-specific skill for success in team sports, dependent on both strength and reactive strength. The sprint approaching the COD and degrees of the turn are factors influencing the specificity of the COD. Thus, CODs have been suggested to be categorized as force- (> 90°) and velocity-dominant (< 90°) dependent on the degree of the turn. When training programmes fail to provide a significant increase in COD performance, it is often due to neglecting the task-specific demands of the COD. As such, 23 male football players volunteered to complete a randomized controlled trial, investigating the association of maximal strength and power performance with performance in a force- (180°) and velocity-dominant (45°) COD, with a 4 m and 20 m sprint approach. Three strength and three plyometric exercises, matched in movement patterns, were used. Muscle activity of the different conditions was also compared. The correlational analysis revealed that better performance in the plyometric tests were associated with less time to complete both force- and velocity-dominant CODs, supported by similarities in muscle activation. None of the performances in strength exercises correlated to COD performance, due to the slow contraction velocity of maximal lifts. It was concluded that plyometrics share more physical similarities with CODs than the strength exercises.

Decisive Factors for a Greater Performance in the Change of Direction and Its Angulation in Male Basketball Players

A study was made to initially evaluate whether the age category directly could influence anthropometric measurements, functional movement tests, linear sprint (30 m) and strength. Moreover, and as the main purpose, this study aimed to examine the relationship between the time execution and angles in different changes of direction (COD) test with the analyzed sport performance variables. A total sample of 23 basketball players (age: 17.5 ± 2.42 years; height: 184.6 ± 6.68 cm; body weight: 78.09 ± 11.9 kg). Between-groups’ comparison explored the differences between basketball categories (Junior, n = 12; Senior, n = 11). The COD variables were divided by the time execution into low responders (LR) and high responders (HR) to establish comparisons between groups related to COD time execution. Pearson’s correlation coefficient was used to establish correlations between different CODs and sport performance variables. The results showed a greater influence of age category upon COD performance, especially when the cutting angle was sharper (7.05% [Confidence limits (CL) 90%: 2.33; 11.99]; Quantitative chances (QC) 0/2/98), in which athletes need greater application of strength. Moreover, the sharper the angle or the larger the number of cuts made, the greater the relationship with the vertical force–velocity profile (−42.39 [CL 90%: −57.37; −22.16]; QC 100/0/0%). Thus, the usefulness of the f–v profile to implement training programs that optimize the f–v imbalance and the improvement of the COD performance in basketball players is suggested.

Relationships between Linear Sprint, Lower-Body Power Output and Change of Direction Performance in Elite Soccer Players

The aim of this study was to investigate the relationship between linear sprint, power output obtained during a squat and change of direction (COD) performance. Fifteen elite soccer players participated in this study (age = 21.7 ± 0.72 years, body mass = 74.9 ± 9.11 kg, body height = 180.4 ± 7 cm, training experience = 9 ± 1.5 years). To examine these correlations a following battery of tests were carried out: 20-m linear sprint, one-repetition maximum (1RM) squat strength, peak power output obtained during a squat at 50% 1RM and time obtained in two 20-m COD tests with different angles of direction change (90° and 135°). In addition, COD deficits (90°-COD_DEF and 135°-COD_DEF) for both COD tests were calculated. The Spearman’s rank order correlation showed a nearly perfect statistical relationship between the 90°-COD and the 90°-COD_DEF (r = 0.9; p < 0.001). In the case of 90°-COD_DEF, there was a large statistical relationship with 135°-COD_DEF (r = 0.59; p = 0.021). Moreover, there was a nearly perfect statistical relationship between 135°-COD and 135°-COD_DEF (r = 0.91; p < 0.001). The statistically insignificant (p > 0.05) relationship between 20-m linear sprint time, power output obtained during a squat at 50% 1RM, 1RM squat strength level and both COD test, as well as both COD deficits were found. Results of the present study showed that 20-m linear sprinting speed, 1RM squat strength, power output obtained during squat at 50% 1RM and COD ability at 90° and 135° angles, are separate physical qualities. Moreover, it seems that COD deficit provides a more isolated measure of COD ability than the COD tests alone and does not must be limited to a specific angle, but provides knowledge about the COD ability in a range of other angles, at least concerning 90° and 135° COD angles.

Predicting Visual-Motor Performance in a Reactive Agility Task from Selected Demographic, Training, Anthropometric, and Functional Variables in Adolescents

Reactive agility (RA) directly refers to athletes' visuomotor processing of the specific conditions for team sports. The aim of the study was to identify the factors among age, gender, sport discipline, time participation in a sports activity, reaction time, and visual field which could have an impact on visual-motor performance in RA tasks in young, competitive team sports players. The study included boys (n = 149) and girls (n = 157) aged 13-15 participating in basketball, volleyball and handball. Anthropometric measurements were carried out, and the Peripheral Perception (PP) test was used to evaluate the visual-motor performance under laboratory conditions. The Five-Time Shuttle Run to Gates test was used to determine the RA. A multiple regression analysis was performed to identify the relationships between the visual-motor performance in an RA task (dependent variable) and the remaining independent variables (continuous and categorical). The findings of the current study indicate that the main predictive factors of visual-motor performance in RA among young athletes are gender (ß = -0.46, p < 0.000) and age (ß = -0.30, p < 0.000). Moreover, peripheral perception positively affected the achievements in the RA task in boys (ß = -0.25, p = 0.020). The sport discipline does not differentiate the visual-motor performance in RA in team sports players in the puberty period.

Relationship of Performance Measures and Muscle Activity between a 180° Change of Direction Task and Different Countermovement Jumps

The ability to rapidly perform change of direction (COD) is crucial for performance in Soccer. COD speed is thought to share similarities with countermovement jumps in kinematics and muscle activation. Thus, the objective of the current study was to investigate the relationship between muscle activities in performance measures of a modified 505-agility test and different countermovement jumps. Twenty-one experienced soccer players performed a COD test including the 505-agility test and uni- and bi-lateral horizontal and vertical countermovement jumps. The main findings were that the vertical bilateral and horizontal unilateral countermovement jump were able to predict total time to complete the COD, but not 505-agility time. Muscle activity in the COD and countermovement jumps was only distinguished by a higher peak muscle activity for the adductor longus, semitendinosus and biceps femoris in the COD to stabilize the hip and decelerate knee joint movements when turning compared with the jumps. Conclusively, the relationship between performance in countermovement jumps and total time to complete the COD test was due to longer sprint distances, which makes the distinction between performances bigger. Peak muscle activity of most muscles is similar between the jumps and the COD step, indicating similar muscular demands between these activities.