Positive Effects of Plyometric vs. Eccentric-Overload Training on Performance in Young Male Handball Players

This study aimed to compare the effects of two 8-week in-season strength-training programs on handball players' physical and technical parameters. Thirty-six male athletes were randomly separated into three groups: a control group (n = 12), a plyometric training group (PG, n = 12), and an eccentric-overload training group (EG, n = 12). The PG and EG performed upper- and lower-limb plyometric or eccentric-overload exercises, respectively, three times per week. Control groups performed regular handball training. The athletes were assessed for counter movement jump (CMJ) and Abalakov vertical jump (ABK) height, 15 m linear sprint time, handball-throwing speed (i.e., penalty throw; 3-step running throw; jump throw), and cardiorespiratory endurance through the 20 m shuttle-run test. Heart rate and blood lactate were measured at the end of the endurance test. No baseline differences were noted for dependent variables between groups. The session rating of perceived exertion was similar between the intervention groups (PG = 361 ± 12.2 AU; EG = 370 ± 13.3 AU). The ANOVA revealed significant (p < 0.05; Δ = 5-9%; effect size (ES) = 0.45-1.96). Similar improvements for experimental groups compared to the control group for CMJ, ABK jump, penalty throw, 3-step running throw, and jump throw. However, interventions did not affect 15 m, cardiorespiratory endurance, nor heart rate or blood lactate after the endurance test. In conclusion, an 8-week handball intervention by performing plyometric or eccentric-overload training in-season improves the physical and technical parameters of male players when compared to regular handball practice.

A Systematic Review with Meta-Analysis on the Effects of Plyometric-Jump Training on the Physical Fitness of Combat Sport Athletes

We aimed to assess the athletic performance changes in combat sport athletes (CoSAs) after plyometric-jump training (PJT), compared to control conditions, through a systematic review with meta-analysis. Following PRISMA guidelines, three electronic databases were searched for includable articles, according to a PICOS approach. Using a random-effects model, Hedges' g effects sizes (ES) were calculated. Heterogeneity was assessed using the I² statistic, with values of <25%, 25-75%, and >75% representing low, moderate, and high levels of heterogeneity, respectively. Statistical significance was set at p ≤ 0.05. The certainty of evidence was assessed using the GRADE approach. Twelve eligible articles were identified for systematic review, seven of high quality and five of moderate quality, according to the PEDro scale. The studies recruited taekwondo, silat, wrestling, judo, fencing, and karate athletes (292 total participants), including specific-active and active controls. Most participants had a mean age of <18 years and were males (n = 225). Compared to the control, PJT programmes, involving 4-12 weeks and 2-3 sessions per week, induced small to moderate improvements (ES = 0.47 to 1.04) in athletes' maximal strength (e.g., 1RM squat), vertical jump height, change-of-direction speed, and specific performance (e.g., fencing movement velocity), although without meaningful effects on body mass, fat mass, and muscle mass (ES = 0.02 to -0.06). Most (7 of 8) outcomes attained low heterogeneity. The outcome-level GRADE analysis indicated a certainty of evidence from low to moderate. In conclusion, PJT, when compared to control conditions, may improve CoSA athletic performance.

Effects of Exercise Frequency with Complex Contrast Training on Measures of Physical Fitness in Active Adult Males

Complex contrast training (CCT) is an exercise modality that utilizes both high-load resistance activity and low-load plyometric activity in a set-by-set fashion within a single exercise session. Such a combination of exercises targets multiple aspects of the force−velocity curve and may thus lead to improvement of various components of physical fitness. However, no previous study has attempted to compare the effects of load-equated two vs. three CCT sessions per week on measures of physical fitness. Forty-five male participants aged 21.4 ± 2.0 years were randomly assigned to either two weekly CCT sessions (CCT-2; n = 15), three weekly CCT sessions (CCT-3; n = 15), or an active control group (CG; n = 15). Selected measures of physical fitness were assessed pre- and post-six weeks of training. The tests included the assessment of 15 and 30 m linear sprint speeds, upper (medicine ball throw) and lower limb muscle power (standing long jump and countermovement jump with arm thrust), muscle strength (isokinetic peak knee extensor/flexor torque), and change-of-direction speed (modified agility T-test (MAT)). Significant group−time interactions were observed for all dependent variables (all p < 0.001, ɳp2 = 0.51−0.78) using ANOVA. Post hoc tests indicated significant performance improvements for the CCT-2 and CCT3 groups for all dependent variables (Hedge’s g = 0.28−3.26, %Δ = 2.4−16.7), including the 15 and 30 m linear sprint speeds (p < 0.001), medicine ball throw (p < 0.001), standing long jump (p < 0.001), countermovement jump with arm thrust (p < 0.001), right leg knee extensor (p < 0.001) and flexor peak torque (p < 0.001), left leg knee extensor (p < 0.001) and flexor peak torque (p < 0.001), and change-of-direction speed (p < 0.001). The CCT-3 group showed greater improvements in MAT compared to the CCT-2 group (g = 3.26 vs. 0.70, p < 0.001). In conclusion, compared to active controls, the load-equated CCT-2 and CCT-3 programs provided similar effects on measures of physical fitness in active adult males. However, an athlete’s goal is to improve their MAT score, the CCT-3 program may elicit greater improvements compared with the CCT-2 program.

Change of Direction Ability as a Sensitive Marker of Adaptation to Different Training Configurations, and Different Populations: Results from Four Experiments

This article includes four separate experiments. In the first experiment male beach handball players (n = 24) were randomly assigned to regular training (n = 12) or plyometric and sprint training (n = 12). In the second experiment, male players were assigned to a handball practice only (n = 12), a plyometric training (n = 12), or an eccentric-overload (e.g., versa-pulley machine) training group (n = 12). In the third experiment, participants were assigned to padel training (n = 12) or specific on-court neuromuscular technical actions (n = 12). In the fourth experiment, females between 50-59 years (n = 25), 60-64 years (n = 25), and 65-70 years (n = 25) completed 10 weeks of bench stepping training involving jumps, and were compared to age-matched controls (n = 45). The COD ability was assessed with the 10-m COD ability test (experiments one and two), the COD ability test with 90º and 180º turns (third experiment), and with the timed-up-and-go test (fourth experiment). In experiment one, greater COD improvement was noted in the experimental group compared to the control group (p < 0.05). In experiment two, both intervention groups similarly improved COD when compared to the control group (p < 0.05). In experiment three, although no significant group-time interactions were observed for COD, the experimental group improved all COD measures pre-post-training (p < 0.05), with a larger effect size for COD with 180° turn to the right compared to the control group (effect size = 0.8 vs. 0.3). In experiment four, the three training groups improved COD ability compared to the control group (p < 0.05). In conclusion, COD is a sensitive marker of adaptation to different training configurations in these diverse groups.

Warm-up stretching exercises and physical performance of youth soccer players

This study aims to compare the effects of standard warm-up versus warm-up using stretching exercises on the physical performance of male youth soccer players. Eighty-five male soccer players (age: 10.3 ± 4.3 years; body mass index: 19.8 ± 4.3 kg/m²) were assessed for countermovement jump height (CMJ, cm), 10 m, 20 m and 30 m running sprint speed (s) and ball kicking speed (km/h) for the dominant and non-dominant leg under five (randomized) warm-up conditions. Using 72 h of recovery between conditions, the participants completed a control condition (CC) and four experimental conditions, including static stretching (SSC), dynamic stretching (DSC), ballistic stretching (BSC), and proprioceptive neuromuscular facilitation (PNFC) exercises. All warm-up conditions had a duration of 10 minutes. The main results indicate that no significant differences (p > 0.05) were found between warm-up conditions compared to CC in CMJ (CC = 28.1 ± 4.9; SSC = 28.4 ± 4.9; DSC = 30.9 ± 4.8; BSC = 30.9 ± 5.2; PNFC = 28.4 ± 5.0), 10 m sprint (CC = 2.42 ± 0.4; SSC = 2.50 ± 0.4; DSC = 2.30 ± 0.3; BSC = 2.27 ± 0.3; PNFC = 2.53 ± 0.4), 20 m sprint (CC = 5.42 ± 0.9; SSC = 5.59 ± 0.9; DSC = 5.37 ± 0.9; BSC = 5.40 ± 0.9; PNFC = 5.44 ± 0.9), 30 m sprint (CC = 8.05 ± 1.3; SSC = 8.27 ± 1.3; DSC = 8.01 ± 1.3; BSC = 8.00 ± 1.3; PNFC = 8.12 ± 1.3), ball kicking speed for dominant (CC = 56.2 ± 4.9; SSC = 55.3 ± 5.2; DSC = 56.9 ± 5.8; BSC = 57.3 ± 5.8; PNFC = 55.7 ± 5.2) and non-dominant leg (CC = 52.8 ± 3.4; SSC = 51.8 ± 4.6; DSC = 53.5 ± 5.4; BSC = 53.6 ± 4.9; PNFC = 52.5 ± 4.0). In conclusion, compared to standard warm-up, stretching-based warm-up exerts no effect on male youth soccer players jump height, sprint speed and ball kicking speed.

Combined balance and plyometric training enhances knee function, but not proprioception of elite male badminton players: A pilot randomized controlled study

Objectives

To investigate the effect of combined balance and plyometric training on knee function and proprioception of elite badminton athletes.

Methods

Sixteen elite male badminton players (age: 20.5 ± 1.1 years, height: 177.8 ± 5.1 cm, weight: 68.1 ± 7.2 kg, and training experience: 11.4 ± 1.4 years) volunteered to participate and were randomly assigned to a combined balance and plyometric training (CT) (n = 8) and plyometric (PT) group (n = 8). The CT group performed balance combined with plyometric training three times a week over 6 weeks (40 min of plyometrics and 20 min of balance training); while the PT group undertook only plyometric training for the same period (3-4 sets × 8-12 reps for each exercise). Both groups had the same technical training of badminton.

Results

The knee function and proprioception were assessed at baseline and after the intervention by measuring the performance of single-legged hop tests (LSIO, LSIT, LSIC, LSIS), standing postural sway (COPAP, COPML), and LSI of dominant leg and non-dominant leg. The results showed that as compared to PT, CT induced significantly greater improvements in LSIT and LSIS (p < 0.001) and significant greater percent increase in NAP (p = 0.011). The changes in LSIO, LSIC, DAP, NAP, LSIAP, DML, NML, and LSIML induced by CT did not differ from that induced by PT (p > 0.213).

Conclusion

In elite badminton players, intervention using CT holds great promise to augment the benefits for knee function compared to the intervention using PT only, and at the same time, with at least comparable benefits for proprioception. Future studies are needed to examine and confirm the results of this study.

Programming Plyometric-Jump Training in Soccer: A Review

The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different ages and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and Scopus using keywords related to the main topic of this study (e.g., “ballistic” and “plyometric”). According to the PICOS framework, the population for the review was restricted to soccer players, involved in jump or plyometric training. Among 7556 identified studies, 90 were eligible for inclusion. Only 12 studies were found for females. Most studies (n = 52) were conducted with youth male players. Moreover, only 35 studies determined the effectiveness of a given jump training programming factor. Based on the limited available research, it seems that a dose of 7 weeks (1−2 sessions per week), with ~80 jumps (specific of combined types) per session, using near-maximal or maximal intensity, with adequate recovery between repetitions (<15 s), sets (≥30 s) and sessions (≥24−48 h), using progressive overload and taper strategies, using appropriate surfaces (e.g., grass), and applied in a well-rested state, when combined with other training methods, would increase the outcome of effective and safe plyometric-jump training interventions aimed at improving soccer players physical fitness. In conclusion, jump training is an effective and easy-to-administer training approach for youth, adult, male and female soccer players. However, optimal programming for plyometric-jump training in soccer is yet to be determined in future research.

Effects of Maturation Stage on Sprinting Speed Adaptations to Plyometric Jump Training in Youth Male Team Sports Players: A Systematic Review and Meta-Analysis

Purpose

To determine the effects of maturation stage (eg, classified in the same intervention protocol as early-, and late-mature) on linear sprinting speed adaptations to plyometric jump training (PJT) in youth (aged <18 years) male team sports players.

Patients and Methods

Eligibility criteria was determined based on PICOS: (P) healthy youth male team sport players classified in the same intervention protocol in ≥2 maturation-related categories, based on a recognized maturation stage-determination method, including (but not limited to) Tanner stage; peak height velocity (eg, Mirwald method); radiography-based method (eg, Fels method); (I) athletes exposed to PJT with a minimum of 4 weeks duration; (C) athletes non-exposed to PJT (non-dedicated intervention, ie, only field-based regular training) or performing a parallel intervention not-related with PJT organized by maturation levels; (O) sprinting speed (eg, time, maximal sprint speed) measured in any linear sprint test trajectories before and after the intervention; (S) only randomized controlled and/or parallel trials. Searches were conducted on December 2021 in EMBASE, PubMed, Scopus, SPORTDiscus and Web of Science, restricted to Portuguese, Spanish and English languages, with no restrictions regarding publication date, and no filters applied. The PEDro scale was used to assess the risk of bias in the included studies. Meta-analysis was computed using the inverse variance random-effects model. The significance level was set at p < 0.05.

Results

The search identified 1219 titles. From those, four studies were selected for qualitative and quantitative synthesis. Four studies provided data for sprinting performance, involving 10 experimental and 8 control groups showing a small effect of trained participants on sprinting performance (ES = 0.31; p = 0.064; I2 = 41.3%) when compared to controls. No significant moderator effect was noted for somatic maturity (p = 0.473 between groups).

Conclusion

PJT had no significant effect on sprinting performance, although the inclusion criteria partially may explain that.

Acute Effects of Milk vs. Carbohydrate on Bone Turnover Biomarkers Following Loading Exercise in Young Adult Females

Dairy products and impact exercise have previously been identified to be independently beneficial for bone mineral properties, however, it is unknown how the combination of these two osteogenic interventions may alter acute bone turnover. Using a randomized crossover design, we compared the acute effects of consuming milk vs. an isoenergetic carbohydrate control beverage on bone biomarkers following loading exercise. Thirteen healthy female participants (Age = 20.3 ± 2.3y; BMI = 21.0 ± 1.1 kg/m2) consumed either 550 mL of 0% skim white milk (MILK) or 52.7 g of maltodextrin in 550 mL of water (CHO), both 5 min and 1 h following completion of a combined plyometric (198 impacts) and resistance exercise (3-4 sets/exercise, 8-12 reps/set, ∼75% 1-RM) bout. Venous blood samples were obtained pre-exercise, and 15 min, 75 min, 24 h and 48 h post-exercise to assess serum concentrations of bone resorption biomarkers, specifically carboxyl-terminal crosslinking telopeptide of type I collagen (CTX), receptor activator nuclear factor kappa-β ligand (RANKL), and sclerostin (SOST), as well as bone formation biomarkers, specifically osteoprotegerin (OPG) and osteocalcin (OC). When absolute biomarker concentrations were examined, there were no interaction or group effects for any biomarker, however, there were main time effects (p < 0.05) for RANKL, SOST, and OC, which were lower, and the OPG: OPG/RANKL ratio, which was higher at 75 min post-exercise compared with baseline in both conditions. In addition to assessing absolute biomarker concentrations at specific timepoints, we also evaluated the relative (% change) cumulative post-exercise response (75 min to 48 h) using an area under the curve (AUC) analysis. This analysis showed that the relative post-exercise CTX response was significantly lower in the MILK compared to the CHO condition (p = 0.03), with no differences observed in the other biomarkers. These results show that while milk does not appear to alter absolute concentrations of bone biomarkers compared to CHO, it may attenuate relative post-exercise bone resorption (i.e., blunt the usual catabolic response to exercise).

Relationship Between Isokinetic Knee Strength and Single-Leg Drop Jump Performance 9 Months After ACL Reconstruction

Background:

Deficits in knee strength after anterior cruciate ligament reconstruction (ACLR) surgery are common. Deficits in the single-leg drop jump (SLDJ), a test of plyometric ability, are also found.

Purpose:

To examine the relationship between isokinetic knee strength, SLDJ performance, and self-reported knee function 9 months after ACLR.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Knee isokinetic peak torque, SLDJ jump height, contact time, and reactive strength index (RSI), as well as International Knee Documentation Committee (IKDC) scores were assessed in 116 male, field-sport athletes at 9.2 months after ACLR. SLDJ testing took place in a 3-dimensional biomechanics laboratory. Linear regression models were used to analyze the relationship between the variables.

Results:

A significant relationship was found between ACLR-limb isokinetic knee extensor strength and SLDJ jump height (P < .001, r² = 0.29) and RSI (P < .001, r² = 0.33), and between ACLR-limb isokinetic knee flexor strength and SLDJ jump height (P < .001, r² = 0.12) and RSI (P < .001, r² = 0.15). A significant positive relationship was also found between knee extensor asymmetry and SLDJ jump height asymmetry (P < .001, r² = 0.27) and SLDJ reactive strength asymmetry (P < .001, r² = 0.18). Combined ACLR-limb jump height and contact time best predicted IKDC scores (P < .001, r² = 0.12).

Conclusion:

Isokinetic knee extension strength explained approximately 30% of SLDJ performance, with a much weaker relationship between knee flexion strength and SLDJ performance. Isokinetic strength and SLDJ performance were weak predictors of variation in IKDC scores.

Effects of Plyometric Jump Training on Balance Performance in Healthy Participants: A Systematic Review With Meta-Analysis

Background: Postural balance represents a fundamental movement skill for the successful performance of everyday and sport-related activities. There is ample evidence on the effectiveness of balance training on balance performance in athletic and non-athletic population. However, less is known on potential transfer effects of other training types, such as plyometric jump training (PJT) on measures of balance. Given that PJT is a highly dynamic exercise mode with various forms of jump-landing tasks, high levels of postural control are needed to successfully perform PJT exercises. Accordingly, PJT has the potential to not only improve measures of muscle strength and power but also balance. Objective: To systematically review and synthetize evidence from randomized and non-randomized controlled trials regarding the effects of PJT on measures of balance in apparently healthy participants. Methods: Systematic literature searches were performed in the electronic databases PubMed, Web of Science, and SCOPUS. A PICOS approach was applied to define inclusion criteria, (i) apparently healthy participants, with no restrictions on their fitness level, sex, or age, (ii) a PJT program, (iii) active controls (any sport-related activity) or specific active controls (a specific exercise type such as balance training), (iv) assessment of dynamic, static balance pre- and post-PJT, (v) randomized controlled trials and controlled trials. The methodological quality of studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. This meta-analysis was computed using the inverse variance random-effects model. The significance level was set at p <0.05. Results: The initial search retrieved 8,251 plus 23 records identified through other sources. Forty-two articles met our inclusion criteria for qualitative and 38 for quantitative analysis (1,806 participants [990 males, 816 females], age range 9-63 years). PJT interventions lasted between 4 and 36 weeks. The median PEDro score was 6 and no study had low methodological quality (≤3). The analysis revealed significant small effects of PJT on overall (dynamic and static) balance (ES = 0.46; 95% CI = 0.32-0.61; p < 0.001), dynamic (e.g., Y-balance test) balance (ES = 0.50; 95% CI = 0.30-0.71; p < 0.001), and static (e.g., flamingo balance test) balance (ES = 0.49; 95% CI = 0.31-0.67; p < 0.001). The moderator analyses revealed that sex and/or age did not moderate balance performance outcomes. When PJT was compared to specific active controls (i.e., participants undergoing balance training, whole body vibration training, resistance training), both PJT and alternative training methods showed similar effects on overall (dynamic and static) balance (p = 0.534). Specifically, when PJT was compared to balance training, both training types showed similar effects on overall (dynamic and static) balance (p = 0.514). Conclusion: Compared to active controls, PJT showed small effects on overall balance, dynamic and static balance. Additionally, PJT produced similar balance improvements compared to other training types (i.e., balance training). Although PJT is widely used in athletic and recreational sport settings to improve athletes' physical fitness (e.g., jumping; sprinting), our systematic review with meta-analysis is novel in as much as it indicates that PJT also improves balance performance. The observed PJT-related balance enhancements were irrespective of sex and participants' age. Therefore, PJT appears to be an adequate training regime to improve balance in both, athletic and recreational settings.

Kinematic and Neuromuscular Measures of Intensity During Drop Jumps in Female Volleyball Players

The aim of this study was to assess drop jump (DJ) performance variables (jump height, contact time, and reactive strength index) concomitant to surface electromyography (sEMG) of lower limb muscles during DJs from different drop heights (intensities). The eccentric and concentric phase sEMG from the gastrocnemius medialis, biceps femoris, and vastus medialis muscles were assessed during all tests, with sEMG activity normalized to maximal voluntary isometric contraction (MVIC). In a cross-sectional, study, 10 amateur female volleyball players (age 22.1 ± 1.8 years; body mass 72.9 ± 15.2 kg; height 1.70 ± 0.08 m) completed DJs from six heights [15–90 cm (DJ15 to DJ90)]. During DJs there was no jump-target box to rebound on to. Results of one-way analysis of variance (ANOVA) showed that the jump height, contact time, and reactive strength index were not significantly (p > 0.05) different between drop heights. Mean biceps femoris eccentric and concentric sEMG ranged from 27 to 50%, although without significant differences between drop heights. Mean gastrocnemius medialis eccentric and concentric sEMG remained relatively constant (∼60–80% MVIC) across DJs heights, although eccentric values reached 90–120% MVIC from DJ75 to DJ90. Mean variations of ∼50–100% MVIC for eccentric and ∼50–70% MVIC for concentric sEMG activations were observed in the vastus medialis across DJs heights. The biceps femoris eccentric/concentric sEMG ratio during DJ45 (i.e., 1.0) was lower (p = 0.03) compared to the ratio observed after DJ90 (i.e., 3.2). The gastrocnemius medialis and vastus medialis eccentric/concentric sEMG ratio were not significantly different between drop heights. In conclusion, jumping performance and most neuromuscular markers were not sensitive to DJ height (intensity) in amateur female volleyball athletes.

Stretch-shortening cycle exercises can efficiently optimize gait-symmetry and balance capabilities in children with unilateral cerebral palsy: A randomized controlled trial

BACKGROUND

Children with unilateral cerebral palsy (UCP) experience an asymmetrical gait pattern and poor balance capabilities. Effective interventions, therefore, are needed to facilitate remediation of these functional issues.

OBJECTIVE

This study was set out to investigate the emerging role of stretch-shortening cycle (SSC) exercises on gait-symmetry and balance in children with UCP.

METHODS

In this randomized controlled trial, 42 children with UCP (age; 8 -12 years) were enrolled and received either standard physical rehabilitation (control group; n = 21) or the SSC exercise program plus physical rehabilitation (SSC group; n = 21). Spatial- and temporal-gait symmetry index (GSI) and specific balance capabilities [reactive balance, directional control, movement synchronization, and sensory organization] were assessed before and after 16 sessions that were carried out twice/week over non-sequential days in an 8-week program.

RESULTS

Using the pre-treatment scores as covariates, the post-treatment spatial- (P = 0.006; ηp2= 0.17) and temporal- GSI (P < .001; ηp2= 0.46) scores reduced significantly in the SSC group as compared to the control group, suggesting favorable improvement of gait symmetry. Also, all measures of balance (P < 0.05; ηp2 ranged between 0.10 and 0.29) improved remarkably, post-treatment, in SSC group in comparison with the control group.

CONCLUSION

The evidence from this study suggests that SSC exercises besides standard physical rehabilitation appear to be effective for improving gait symmetry and boosting balance capabilities in children with UCP.

The timeframe for safe resumption of high-level mobility following traumatic brain injury is currently unknown: a systematic review

PURPOSE

To examine the safety of high-level mobility (HLM) prescription in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury (TBI) with specific focus on provocation of concussion-like symptoms.

DESIGN

Systematic review. PROSPERO ID: CRD42017069369.

MAIN MEASURES

Extracted data included study design, brain injury severity, time to commence HLM, type of HLM, physiological and symptom monitoring, and rate of adverse events.

RESULTS

Nineteen studies were included in the review. Fifteen studies included participants who commenced HLM within 6 weeks of injury, with the earliest time to commencement being 3 days. Overall, adverse events and symptom monitoring were poorly reported. A total of six adverse events were reported across three studies. One of the six adverse events was a concussion-like symptom. No falls were reported. No studies monitored concussion-like symptom provocation in direct relation to HLM.

CONCLUSION

A safe timeframe for return to HLM after moderate-to-extremely severe TBI could not be determined due to insufficient reporting of symptom monitoring and adverse events. Further research into the safety of HLM in the early sub-acute rehabilitative stage after moderate-to-extremely severe TBI is required in order to better understand potential sequelae in this population.IMPLICATIONS FOR REHABILITATIONHigh-level mobility assessment and training is commonly reported in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury.There is no consensus on a safe timeframe to commence high-level mobility assessment or training after moderate-to-extremely severe traumatic brain injury.High-level mobility assessment and training appears to be safe in the early sub-acute phase following moderate-to-extremely severe traumatic brain injury, however, adverse events and symptoms are poorly reported.Clinicians should continue to proceed with caution when assessing and prescribing high-level mobility for patients with moderate-to-extremely severe traumatic brain injury in the early sub-acute phase of recovery and monitor for risks such as falls and exacerbation of concussion-like symptoms.

Effects of High-Speed Versus Traditional Resistance Training in Older Adults

BACKGROUND

The losses of strength, agility, balance, and functionality caused by aging are harmful to the elderly population. Resistance training (RT) may be an efficient tool to mitigate such neuromuscular decline and different RT methods can be used. Therefore, it is important to investigate the different responses to different training methods.

HYPOTHESIS

Eight weeks of traditional resistance training (TRT) are expected to promote similar results to high-speed training (HST) in physical functional performance (PFP) and quality of life in the elderly.

STUDY DESIGN

A clinical trial.

LEVEL OF EVIDENCE

Level 3.

METHODS

Participants (n = 24) with a mean age of 67.8 ± 6.3 years completed 8 weeks of RT. They were allocated into HST (n = 12) and TRT (n = 12). TRT involved training with 10 to 12 repetitions at controlled velocity until momentary muscle failure, while HST involved performing 6 to 8 repetitions at 40% to 60% of 1 repetition maximum (1RM) at maximum velocity. Pre- and posttraining, the participants were tested for (1) maximum strength in the 45° leg press and chest press; (2) PFP in the 30-second chair stand, timed-up-and-go (TUG), and medicine ball throw test; and (3) quality of life.

RESULTS

Both groups improved muscle strength in the 45° leg press, with greater increases for TRT (HST: +21% vs TRT: +49%, P = 0.019). There was no change in chest press strength for HST (-0.6%) (P = 0.61), but there was a significant increase for the TRT group (+21%, P = 0.001). There was a similar improvement (P < 0.05) for both groups in TUG (HST: 7%; TRT: 10%), chair stand (HST: 18%; TRT: 21%), and medicine ball throwing performance (HST: 9%; TRT: 9%), with no difference between groups (P = 0.08-0.94). Emotional aspect significantly increased by 20% (P = 0.04) in HST and 50% (P = 0.04) in TRT.

CONCLUSION

Both TRT and HST are able to promote improvements in functional performance in the elderly with greater in strength gains for TRT. Therefore, exercise professionals could choose based on individual characteristics and preferences.

CLINICAL RELEVANCE

The findings provide important insights into how health care professionals can prescribe HST and TRT, considering efficiency, safety, and individual aspects.

Effects of jump training on physical fitness and athletic performance in endurance runners: A meta-analysis

This systematic review and meta-analysis aimed to assess the effects of jump training (JT) on measures of physical fitness and athletic performances in endurance runners. Controlled studies which involved healthy endurance runners, of any age and sex, were considered. A random-effects model was used to calculate effect sizes (ES; Hedge's g). Means and standard deviations of outcomes were converted to ES with alongside 95% confidence intervals (95%CI). Twenty-one moderate-to-high quality studies were included in the meta-analysis, and these included 511 participants. The main analyses revealed a significant moderate improvement in time-trial performance (i.e. distances between 2.0 and 5.0 km; ES = 0.88), without enhancements in maximal oxygen consumption (VO₂max), velocity at VO₂max, velocity at submaximal lactate levels, heart rate at submaximal velocities, stride rate at submaximal velocities, stiffness, total body mass or maximal strength performance. However, significant small-to-moderate improvements were noted for jump performance, rate of force development, sprint performance, reactive strength, and running economy (ES = 0.36-0.73; p < 0.001 to 0.031; I² = 0.0% to 49.3%). JT is effective in improving physical fitness and athletic performance in endurance runners. Improvements in time-trial performance after JT may be mediated through improvements in force generating capabilities and running economy.

The Protective Effect of Neuromuscular Training on the Medial Tibial Stress Syndrome in Youth Female Track-and-Field Athletes: A Clinical Trial and Cohort Study

CONTEXT

Few reports have analyzed the effects of neuromuscular (NM) training programs on the injury incidence among youth female track-and-field athletes.

OBJECTIVE

To determine the effects of NM training on reducing lower limb injury incidence and to establish its effects on countermovement jump performance, balance, 30-m sprint, and joint position sense in youth female track-and-field athletes.

DESIGN

Single-blind, randomized controlled clinical trial.

SETTING

Sports research laboratory.

PARTICIPANTS

Twenty-two female athletes were allocated into 2 groups: Conventional (CONV) training (n = 11; age = 15.3 [2.1] y) and NM training (n = 11; age = 15.0 [2.7] y).

INTERVENTIONS

Interventions were performed during the preseason of 6 weeks. The CONV training included anaerobic, strength, and aerobic training. The NM training consisted of a multicomponent program that integrated jumps, landings, and running with strength, endurance, agility, balance, and CORE training.

MAIN OUTCOME MEASURES

A follow-up of the cohorts was carried out through the evaluation of lower limb injuries (main outcome) during a regular season (weeks 7-18). Secondary outcomes were measured before and after the intervention: Y-balance test, active joint repositioning, ground reaction force, and countermovement jump height.

RESULTS

The injury incidence rate was 17.89 injuries per 1000 hours athlete-exposure in CONV training, and 6.58 in NM training (relative risk = 0.38; 95% confidence interval,  0.18 to 0.82; P = .044). Particularly, the medial tibial stress syndrome incidence rate was 5.96 injuries per 1000 hours athlete-exposure in CONV training and 0.82 in NM training (relative risk = 0.17; 95% confidence interval, 0.02 to 1.12; P = .012). In addition, a significant training × time interaction was noted, favoring improvements in 30-m sprint and countermovement jump height after NM.

CONCLUSION

The NM training may improve youth female athlete's physical fitness and reduce their injury relative risk of medial tibial stress syndrome injury.

The Effects of Combined Balance and Complex Training Versus Complex Training Only on Measures of Physical Fitness in Young Female Handball Players

PURPOSE

To examine the effects of balance exercises conducted prior to complex training (bCT) versus complex training (CT) only on measures of physical fitness in young female elite handball players.

METHODS

Participants aged 17 years were randomly assigned to bCT (n = 11) or CT (n = 12). The 2 training interventions lasted 8 weeks with 2 sessions per week in replacement of some technical/tactical handball exercises and were matched for total training volume. Before and after training, tests were performed for the evaluation of proxies of muscle power (countermovement jump height, standing long-jump distance, and reactive strength index), muscle strength (back half-squat 1-repetition maximum), dynamic balance (Y-balance test), linear sprint speed (20-m sprint test), and change-of-direction speed (T test).

RESULTS

Two-factor repeated-measures analysis of variance revealed significant group × time interactions for the reactive strength index (d = 0.99, P = .03) and Y-balance test score (d = 1.32, P < .01). Post hoc analysis indicated significant pre-post reactive strength index improvements in CT (d = 0.69, P = .04) only. For the Y-balance test, significant pre-post increases were found in bCT (d = 0.71, P = .04) with no significant changes in CT (d = 0.61, P = .07). In addition, significant main effects of time were observed for half-squat 1-repetition maximum, countermovement jump, standing long jump, and T test performance (d = 1.50 to 3.10, P < .05).

CONCLUSIONS

Both bCT and CT interventions were effective in improving specific measures of physical fitness in young elite female handball players. If the training goal is to improve balance in addition, balance exercises can be conducted within a CT training session and prior to CT exercises.

Effects of Complex Training on Sprint, Jump, and Change of Direction Ability of Soccer Players: A Systematic Review and Meta-Analysis

The aim of this meta-analysis was to evaluate the effects of complex training (CT) on sprint, jump, and change of direction (COD) ability among soccer players. After an electronic search, 10 peer-reviewed articles were considered in the meta-analysis. The athletes included in this meta-analysis were amateur to professional level male soccer players (age range, 14–23 years). These studies incorporated CT in soccer players who were compared to a control group. Significant moderate to large improvements were observed in the CT group [sprint: standard mean difference (SMD) = 0.92–1.91; jump: SMD = 0.96–1.58; COD: SMD = 0.97–1.49] when compared to control groups. Subgroup analysis were also conducted based on age, duration, and competitive level. The beneficial effects of CT were greater in players <18 vs. ≥18 years (linear sprinting; SMD = 2.01 vs. −0.13), after ≥8 vs. <8 weeks (jumping and COD; SMD = 1.55–2.01 vs. 0.31–0.64, respectively) and among professional vs. amateur players (linear sprinting and with COD; SMD = 1.53–1.58 vs. 0.08–0.63, respectively). In conclusion, regular soccer training programs may be supplemented with CT to improve sprint, jump, and COD performance. A longer duration of CT (≥8 weeks) seems to be optimal in improving the physical abilities of soccer players. Professional players and <18 years players may benefit more from CT program.

Ten Days of Curcumin Supplementation Attenuates Subjective Soreness and Maintains Muscular Power Following Plyometric Exercise

Curcumin has become a popular product used to decrease inflammation and enhance recovery from exercise.

PURPOSE

To determine the effects of curcumin supplementation on delayed onset muscle soreness and muscle power following plyometric exercise.

METHODS

Participants (n = 22; five females, 17 males) consumed either curcumin (500 mg) or placebo twice daily for 10 days (6 days pre, day of and 3 days post exercise). Participants completed 5 x 20 drop jumps on day 7. Blood sampling and recovery tests were assessed at pre-supplementation, 24-hours and immediately pre-exercise, and immediately post-, 24, 48 and 72-hours post-exercise. Blood markers included serum creatine kinase (CK) and erythrocyte sedimentation rate (ESR), while soreness was measured during a squat and post vertical jump.

RESULTS

Both groups experienced muscle damage post-exercise with elevated CK (403 ± 390 ul; p < 0.01), soreness with squatting (38 ± 29 mm; p < 0.01), and vertical jump (36 ± 30 mm; p < 0.01). Soreness was greater in placebo vs. curcumin 48 h and 72 h post-exercise (p < 0.01); however, CK was not significantly different between groups (p = 0.28) despite being >200 IU·L^-1 greater 24 hr post exercise in placebo vs. curcumin. ESR was significantly greater immediately post-exercise (6.3 ± 5.6 vs. 3.4 ± 2.6 mm/hr; p = 0.03), however these were within the normal range for this test and not significantly different between groups (p = 0.25). Vertical jump decreased over time in the placebo, but not curcumin group (19.8 ± 4.8 vs. 21.4 ± 3.2 in; p = 0.01).

CONCLUSION

These data suggest curcumin reduces soreness and maintains muscular power following plyometric exercise.

Effects of Plyometric Jump Training in Female Soccer Player's Physical Fitness: A Systematic Review with Meta-Analysis

We aimed to assess the effects of plyometric jump training (PJT) on female soccer player’s physical fitness. To this aim, a systematic review with meta-analysis (SRMA) was conducted. The electronic databases PubMed, MEDLINE, Web of Science, and SCOPUS were used. To qualify for inclusion, peer-reviewed studies must have included (i) a PJT programme of ≥2 weeks, (ii) healthy athletes, (iii) a control group, and (iv) physical fitness outcomes (e.g., jump; sprint). Studies were excluded if (i) they incorporated injuried female soccer players, (ii) did not involve PJT or an active control group, (iv) lack of baseline and/or follow-up data. Data was meta-analyzed using the inverse variance random-effects model. Ten moderate-to-high quality studies were included in the analyses, comprising 13 training groups (n = 140) and 10 control groups (n = 110). Small to large (ES = 0.60–2.24; p = 0.040 to <0.001) effects were noted for countermovement jump, drop jump, kicking performance, linear sprint, change of direction speed, and endurance. The moderator analyses (i.e., PJT duration, age groups, competitive level, and soccer experience) revealed no significant differences between groups. In conclusion, PJT may improve the physical fitness of female soccer players. Such improvements might be expected after PJT interventions with six or more weeks of duration, and in players with different chronological ages, competitive levels and soccer experience.

Strength Training Habits in Amateur Endurance Runners in Spain: Influence of Athletic Level

This study determined the strength training (ST) habits of amateur endurance runners in Spain regarding athletic level. A sixteen-item online questionnaire comprised of (i) demographic information, (ii) performance, and (iii) training contents was completed by 1179 athletes. Five group levels were determined according to the personal best times of the athletes in a 10-km trial (LG1: level group 1, 50–55 min; LG2: level group 2, 45–50 min; LG3: level group 3, 40–45 min; LG4: level group 4, 35–40 min; LG5: level group 5, 30–35 min). Most athletes (n = 735, 62.3%) perceived ST as being a key component in their training program. Resistance training (RT) was reported as a ST type used by 63.4% of the athletes, 66.9% reported using bodyweight exercises, 46.8% reported using plyometric training, 65.6% reported using uphill runs, and 17.8% reported using resisted runs. The prevalence of runners who excluded ST from their training programs decreased as the athletic performance level increased (18.2% in lower-level athletes vs. 3.0% in higher-level), while the inclusion of RT, bodyweight exercises, plyometric training, and uphill and resisted runs was more frequent within higher-level groups. Most athletes included ST using low-to-moderate loads and high a number of repetitions/sets comprised of RT, plyometric training, resisted runs, and core, respiratory, and foot muscles training.

The Effects of Loaded Plyometric Exercise during Warm-Up on Subsequent Sprint Performance in Collegiate Track Athletes: A Randomized Trial

Prior evidence demonstrates the efficacy by which plyometric activities during warm-up conditions augment the subsequent performance in power-centric exercise. We investigated the acute effects of loaded jump squats incorporated into a standard sprinters’ warm-up protocol on subsequent sprint performance in collegiate track athletes. Sprint times of 22 male and female collegiate track athletes were measured in 10-m intervals during a 30-m sprint trial following a standard sprinters’ warm-up routine with or without plyometric exercise. Subjects were tested on two separate occasions, once with loaded jump squats as the experimental treatment (two sets of eight jumps, load = 13% bodyweight) (PLYO) and once with time-equated rest as the control treatment (CON). Treatments were implemented following a standard sprinters’ warm-up routine familiar to the subjects. A dependent T-test was used for comparison of sprint interval times between conditions with a significant effect indicated by a p-value < 0.05. Sprint time did not differ between CON vs. PLYO at the 10 m (PLYO = 1.90 ± 0.12 s vs. CON = 1.90 ± 0.11 s, p = 0.66), 20 m (PLYO = 3.16 ± 0.21 s vs. CON = 3.15 ± 0.19 s, p = 0.53), and 30 m (PLYO = 4.32 ± 0.32 s vs. CON = 4.31 ± 0.28 s, p = 0.61) intervals. There was no interaction between treatment and sex, sex-specific ranking (above vs. below sex-specific mean), or sprint event (short vs. short–long vs. long) for 10 m, 20 m, or 30-m interval sprint times. At least within the limits of the current investigation, no evidence was provided to suggest that jump squats loaded at 13% bodyweight are an effective means to acutely potentiate sprint performance in collegiate track athletes. However, a further examination of responders indicates that the present loaded jump squat protocol may preferentially potentiate sprint performance in faster male athletes.

Effect of Plyometric versus Ankle Stability Exercises on Lower Limb Biomechanics in Taekwondo Demonstration Athletes with Functional Ankle Instability

Background: This study aimed to compare the effects of plyometric and ankle stability exercises on the dynamic balance and lower limb kinematic and kinetic parameters of Taekwondo demonstration athletes with functional ankle instability. Methods: Fourteen subjects participated in this study and were randomly divided into two groups: a plyometric exercise group (n = 7) and an ankle stability exercise group (n = 7). Exercises were performed twice a week for 8 weeks. A Y-balance test was used to measure dynamic balance, and a motion analysis system and force plate were used to collect kinematic and kinetic parameters during single-leg drop landing. A paired t-test was used for intragroup comparisons, and an independent t-test was used for intergroup comparisons. Results: In both groups, exercise increased dynamic balance and shock absorption and reduced postural sway on the anteroposterior displacement (p < 0.05). The plyometric exercise group decreased their ankle dorsiflexion and increased their knee and hip joint flexion at maximum knee flexion (p < 0.05). In contrast, the stability exercise increased their ankle plantar flexion at initial contact (p < 0.05). Conclusions: The plyometric exercise group altered their landing strategies using their knee and hip joints to control ankle instability at landing. This study suggests that the application of plyometric exercises in ankle rehabilitation would improve stability and shock absorption and help prevent injuries during Taekwondo demonstrations.

Effects of plyometric jump training in female soccer player's vertical jump height: A systematic review with meta-analysis

To assess the effects of plyometric jump training (PJT) in female soccer player's vertical jump height, a review was conducted using the data sources PubMed, MEDLINE, Web Of Science and SCOPUS. Only peer-review articles were included. To qualify for inclusion in the meta-analysis, studies must have included (i) a PJT programme of at least 2 weeks, (ii) cohorts of healthy female soccer players with no restriction for age, (iii) a control group, (iv) a measure of countermovement jump (CMJ). The inverse variance random-effects model for meta-analyses was used. From 7,136 records initially identified through database searching, 8 were eligible for meta-analysis, comprising 9 training groups (n = 99) and 9 control groups (n = 94). The magnitude of the main effect was moderate (ES = 1.01 [95%CI = 0.36-1.66], Z = 3.04, p = 0.002). Sub-group analyses were performed (i.e., PJT frequency, duration and total number of sessions), revealing no significant subgroup differences (p = 0.34-0.96). Among the studies included in this review, none reported injury or other adverse effects. In conclusion, PJT is effective in female soccer players for the improvement of vertical jump height. In future, research must identify specific dose-response relationships following PJT, particularly in the long term.

Similar Cardioventilatory but Greater Neuromuscular Stimuli With Interval Drop Jump Than With Interval Running

CONTEXT

Drop jumps and high-intensity interval running are relevant training methods to improve explosiveness and endurance performance, respectively. Combined training effects might, however, be achieved by performing interval drop jumping.

PURPOSE

To determine the acute effects of interval drop jumping on oxygen uptake (V˙O2)-index of cardioventilatory/oxidative stimulation level and peripheral fatigue-a limiting factor of explosiveness.

METHODS

Thirteen participants performed three 11-minute interval training sessions during which they ran 15 seconds at 120% of the velocity that elicited maximal V˙O2 (V˙O2max) (ITrun), or drop jumped at 7 (ITDJ7) or 9 (ITDJ9) jumps per 15 seconds, interspersed with 15 seconds of passive recovery. V˙O2 and the time spent above 90% of V˙O2max (V˙TO2max) were collected. Peripheral fatigue was quantified via preexercise to postexercise changes in evoked potentiated quadriceps twitch (ΔQT). Power output was estimated during ITDJs using optical sensors.

RESULTS

All participants reached 90% of V˙O2max or higher during ITrun and ITDJ9, but only 11 did during ITDJ7. V˙TO2max was not different between ITrun and ITDJ9 (145 [76] vs 141 [151] s; P = .92) but was reduced during ITDJ7 (28 [26] s; P = .002). Mean ΔQT in ITDJ9 and ITDJ7 was not different (-17% [9%] vs -14% [8%]; P = .73) and greater than in ITrun (-8% [7%]; P = .001). No alteration in power output was found during ITDJs (37 [10] W·kg-1).

CONCLUSION

Interval drop jumping at a high work rate stimulated the cardioventilatory and oxidative systems to the same extent as interval running, while the exercise-induced increase in fatigue did not compromise drop jump performance. Interval drop jumping might be a relevant strategy to get concomitant improvements in endurance and explosive performance.

The Effects of Lower-Extremity Plyometric Training on Soccer-Specific Outcomes in Adult Male Soccer Players: A Systematic Review and Meta-Analysis

BACKGROUND

Plyometric training is a specific form of strength training that is used to improve the physical performance of athletes. An overview of the effects of plyometric training on soccer-specific outcomes in adult male soccer players is not available yet.

PURPOSE

To systematically review and meta-analyze the effects of plyometric training on soccer-specific outcome measures in adult male soccer players and to identify which programs are most effective.

METHODS

PubMed, Embase/Medline, Cochrane, PEDro, and Scopus were searched. Extensive quality and risk of bias assessments were performed using the Cochrane ROBINS 2.0 for randomized trials. A random effects meta-analysis was performed using Cochrane Review Manager 5.3.

RESULTS

Seventeen randomized trials were included in the meta-analysis. The impact of plyometric training on strength, jump height, sprint speed, agility, and endurance was assessed. Only jump height, 20-m sprint speed, and endurance were significantly improved by plyometric training in soccer players. Results of the risk of bias assessment of the included studies resulted in overall scores of some concerns for risk of bias and high risk of bias.

CONCLUSION

This review and meta-analysis showed that plyometric training improved jump height, 20-m sprint speed, and endurance, but not strength, sprint speed over other distances, or agility in male adult soccer players. However, the low quality of the included studies and substantial heterogeneity means that results need to be interpreted with caution. Future high-quality research should indicate whether or not plyometric training can be used to improve soccer-specific outcomes and thereby enhance performance.

Biomechanical mechanisms of jumping performance in youth elite female soccer players

We aimed to determine key biomechanical parameters explaining age-related jumping performance differences in youth elite female soccer players. Multiple biomechanical parameters from countermovement (CMJ) squat (SJ) and drop (DJ) jump testing of elite female soccer players (n = 60) within the same national training centre were analysed across ages 9-11y, 12-14y and 15-19y. Effects of age group and jump type on jump height were found, with the older jumping higher than the younger groups in all jumps (P < 0.05). For DJ, higher reactive strength index was found for older, compared to each younger group (P < 0.001). For CMJ and SJ, peak power was the most decisive characteristic, with significant differences between each group for absolute peak power (P < 0.0001) and body-weight-normalised peak power in CMJ (57 ± 7W/kg, 50 ± 7W/kg, 44.7 ± 5.5W/kg; P < 0.05) and between the older and each younger group in SJ (56.7 ± 7.1W/kg, 48.9 ± 7.1W/kg, 44.6 ± 6W/kg; P < 0.01). Age-related differences in jumping performance in youth elite female soccer players appear to be due to power production during standing jumps and by the ability to jump with shorter ground contact times during reactive jumps.

Effects of plyometric jump training on the physical fitness of young male soccer players: Modulation of response by inter-set recovery interval and maturation status

The effects of plyometric jump training on the physical fitness of male youth (age = 10-17 years) soccer players was examined in relation to inter-set recovery intervals and the maturity of the players in a single-blind, randomized-and controlled crossover trial. Jumping tests and kicking velocities were measured before (T₀), after a 6 week control period (T₁), after 6 weeks of plyometrics (T₂), after 6 weeks of wash-out (T₃), and after a further 6 weeks of plyometrics (T₄). Subjects were divided into pre- and post- peak-height-velocity (PHV) groups, and were randomly assigned to 30 s or 120 s inter-set intervals during periods T₂ and T₄. Any changes in jumping and maximum kicking velocities during T₁ and T_3, had trivial effect sizes (0.01-0.15), but small to moderate improvements (effect size = 0.20-0.99) were observed in both groups during T₂ and T₄. Gains in pre-PHV players were similar for the two inter-set intervals, but gains in post-PHV players were greater (p < 0.05) with an inter-set recovery of 120 s than with a 30 s recovery. We conclude that plyometric jump training improves the physical fitness of adolescents, irrespective of their maturity, but that in older individuals gains are greater with a longer inter-set recovery interval.

The Importance of Impact Loading and the Stretch Shortening Cycle for Spaceflight Countermeasures

Pronounced muscle and bone losses indicate that the musculoskeletal system suffers substantially from prolonged microgravity. A likely reason for these detrimental adaptations in the lower extremity is the lack of impact loading and the difficulty to apply large loading forces on the human body in microgravity. The human body is well adapted to ambulating in Earth’s gravitational field. A key principle herein is the periodic conversion of kinetic to elastic energy and vice versa. Predominantly tendons and to a lesser extent muscles, bones and other tissues contribute to this storage and release of energy, which is most efficient when organized in the stretch-shortening cycle (SSC). During SSC, muscles, especially those encompassing the ankle, knee, and hip joints, are activated in a specific manner, thereby enabling the production of high muscle forces and elastic energy storage. In consequence, the high forces acting throughout the body deform the viscoelastic biological structures sensed by mechanoreceptors and feedback in order to regulate the resilience of these structures and keep strains and strain rates in an uncritical range. Recent results from our lab indicate, notably, that SSC can engender a magnitude of tissue strains that cannot be achieved by other types of exercise. The present review provides an overview of the physiology and mechanics of the natural SSC as well as the possibility to mimic it by the application of whole-body vibration. We then report the evidence from bed rest studies on effectiveness and efficiency of plyometric and resistive vibration exercise as a countermeasure. Finally, implications and applications of both training modalities for human spaceflight operations and terrestrial spin-offs are discussed.

NONOPERATIVE TREATMENT FOR INJURIES TO THE IN-SEASON THROWING SHOULDER: A CURRENT CONCEPTS REVIEW WITH CLINICAL COMMENTARY

Repetitive overhead throwing generates tremendous demands on the shoulder joint of the overhead athlete. Clinicians, therapists, and medical staff are charged with optimizing a throwing athlete's shoulder mobility and stability to maximize performance and prevent injury. Modifiable risk factors such as strength asymmetry, glenohumeral range of motion deficits, and scapulothoracic joint abnormalities contribute to the overhead athlete's predisposition to shoulder injury. Most shoulder injuries in the overhead thrower can be successfully treated nonoperatively to allow in-season return to sport. The optimal rehabilitation program must be based on an accurate evaluation of historical and physical information as well as diagnostic imaging. Return to play decisions should be individualized and should weigh subjective assessments along with objective measurements of range of motion, strength, and function. The purpose of this clinical commentary is to summarize the current literature regarding the nonoperative treatment options for these common injuries, and to present a treatment plan to safely return these athletes to the field of play.

Level of evidence

5.

Plyometric Training Improves Sprinting, Jumping and Throwing Capacities of High Level Female Volleyball Players Better Than Skill-Based Conditioning

There is an evident lack of studies on the effectiveness of plyometric- and skill-based-conditioning in volleyball. This study aimed to evaluate effects of 12-week plyometric- and volleyball-skill-based training on specific conditioning abilities in female volleyball players. The sample included 41 high-level female volleyball players (21.8 ± 2.1 years of age; 1.76 ± 0.06 cm; 60.8 ± 7.0 kg), who participated in plyometric- (n = 21), or skill-based-conditioning-program (n = 20). Both programs were performed twice per week. Participants were tested on body-height, body-mass (BM), countermovement jump (CMJ), standing broad jump (SBJ), medicine ball throw, (MBT) and 20-m sprint (S20M). All tests were assessed at the study baseline (pre-) and at the end of the 12-week programs (post-testing). Two-way ANOVA for repeated measurements showed significant (p<0.05) "Group x Time" effects for all variables but body-height. Plyometric group significantly reduced body-mass (trivial effect size [ES] differences; 1% average pre- to post-measurement changes), and improved their performance in S20M (moderate ES; 8%), MBT (very large ES; 25%), CMJ (large ES; 27%), and SBJ (moderate ES; 8%). Players involved in skill-based-conditioning significantly improved CMJ (large ES; 18%), SBJ (small ES; 3%), and MBT (large ES; 9%). The changes which occurred between pre- and post-testing were more inter-correlated in plyometric-group. Although both training-modalities induced positive changes in jumping- and throwing-capacities, plyometric-training is found to be more effective than skill-based conditioning in improvement of conditioning capacities of female senior volleyball players. Future studies should evaluate differential program effects in less experienced and younger players.

Can Different Complex Training Improve the Individual Phenomenon of Post-Activation Potentiation?

The aims of the present study were (a) to determine whether the two types of complex training and vibration complex training would improve the individual phenomenon of post-activation potentiation (PAP) for every athlete in a team setting; and (b) to compare the acute effect of resistance and plyometric exercise, whole body vibration, complex training and vibration complex training on vertical jump performance. The participants were ten male division I college volleyball and basketball players. They were asked to perform three vertical jumps as a pre-test and were then randomly assigned to one of five PAP protocols, resistance exercise using half squat exercise, plyometric exercise using drop jumps with individualized drop height, whole body vibration using squats on a vibration plate, complex training combining resistance exercise with plyometric exercise, vibration complex training combining whole body vibration with plyometric exercise. Three vertical jumps were performed four minutes after the PAP protocol as a post-test. A two-way repeated-measures analysis of variance was used to examine the differences among the five PAP protocols and between the two testing times. Our results showed that the post-test results were significantly improved compared to the pre-test for the vertical jump height (p = .015) in all PAP protocols. There was, however, an individual phenomenon of PAP in the response to all PAP protocols. In conclusion, this study found that resistance and plyometric exercise, whole body vibration, complex training and vibration complex training induce similar group PAP benefits. However, some athletes decreased their performances in some of the exercises in the study. Therefore, it is not recommended for coaches to arrange the exercises in a team setting.

Effects of Warm-Up and Fatigue on Knee Joint Position Sense and Jump Performance

The purpose of this study was to evaluate the effects of a warm-up and fatigue protocol on the vertical jump and knee joint position sense of sprinters. Thirty-two sprinters were randomly allocated to either a control group (CONT) or a plyometric group (PLYO) that performed a warm-up, followed by a high-intensity plyometric protocol. Absolute (AAE), relative (RAE), and variable (VAE) angular errors and vertical jump were evaluated before and after the warm-up, as well as after the plyometric protocol and again 5 min later. After the warm-up, athletes improved RAE and jump performance. After the plyometric protocol, scores on the RAE, VAE, and the vertical jump performance worsened compared to the control group and to the values obtained after the warm-up. Five minutes later, RAE and vertical jump continued to be impaired. AAE did not show significant differences. The vertical jump is improved after the warm-up, although it is deteriorated after high-intensity plyometry. Regarding knee proprioception, the lack of impairments in the AAE make unclear the effects of the plyometric exercises on knee proprioception.

Type of Ground Surface during Plyometric Training Affects the Severity of Exercise-Induced Muscle Damage

The purpose of this study was to compare the changes in the symptoms of exercise-induced muscle damage from a bout of plyometric exercise (PE; 10 × 10 vertical jumps) performed in aquatic, sand and firm conditions. Twenty-four healthy college-aged men were randomly assigned to one of three groups: Aquatic (AG, n = 8), Sand (SG, n = 8) and Firm (FG, n = 8). The AG performed PE in an aquatic setting with a depth of ~130 cm. The SG performed PE on a dry sand surface at a depth of 20 cm, and the FG performed PE on a 10-cm-thick wooden surface. Plasma creatine kinase (CK) activity, delayed onset muscle soreness (DOMS), knee range of motion (KROM), maximal isometric voluntary contraction (MIVC) of the knee extensors, vertical jump (VJ) and 10-m sprint were measured before and 24, 48 and 72 h after the PE. Compared to baseline values, FG showed significantly (p < 0.05) greater changes in CK, DOMS, and VJ at 24 until 48 h. The MIVC decreased significantly for the SG and FG at 24 until 48 h post-exercise in comparison to the pre-exercise values. There were no significant (p > 0.05) time or group by time interactions in KROM. In the 10-m sprint, all the treatment groups showed significant (p < 0.05) changes compared to pre-exercise values at 24 h, and there were no significant (p > 0.05) differences between groups. The results indicate that PE in an aquatic setting and on a sand surface induces less muscle damage than on a firm surface. Therefore, training in aquatic conditions and on sand may be beneficial for the improvement of performance, with a concurrently lower risk of muscle damage and soreness.

Jump Rope Training: Balance and Motor Coordination in Preadolescent Soccer Players

General physical practice and multidimensional exercises are essential elements that allow young athletes to enhance their coordinative traits, balance, and strength and power levels, which are linked to the learning soccer-specific skills. Jumping rope is a widely-used and non-specific practical method for the development of athletic conditioning, balance and coordination in several disciplines. Thus, the aim of this study was to investigate the effects of a short-term training protocol including jumping rope (JR) exercises on motor abilities and body balance in young soccer players. Twenty-four preadolescent soccer players were recruited and placed in two different groups. In the Experimental group (EG), children performed JR training at the beginning of the training session. The control group (CG), executed soccer specific drills. Harre circuit test (HCT) and Lower Quarter Y balance test (YBT-LQ) were selected to evaluate participant's motor ability (e.g. ability to perform rapidly a course with different physical tasks such as somersault and passages above/below obstacles ) and to assess unilateral dynamic lower limb balance after 8 weeks of training. Statistical analysis consisted of paired t-test and mixed analysis of variance scores to determine any significant interactions. Children who performed jumping rope exercises showed a significant decrease of 9% (p < 0.01, ES = 0.50-0.80) in the performance time of HCT. With regard to the CG, no differences were highlighted (p > 0.05, ES = 0.05-0.2) from pre- to post-training. A training-by-group interaction was found for the composite score in both legs (p < 0.05, Part η(2) > 0.14). Our findings demonstrated that JR practice within regular soccer training enhanced general motor coordination and balance in preadolescent soccer players. Therefore, the inclusion of JR practice within regular soccer training session should encouraged to improve children's motor skills. Key pointsPerforming jumping rope exercises within a regular soccer program can be an additional method to improve balance and motor coordination.The performance improvement in the Harre Circuit Test associated with jump rope training can potentially be attributed to an enhancement of the inter-limb coordination and SSC ability.Results from the present study indicate that young soccer players should be encouraged to practice general physical activities together with sport-specific exercise during their training sessions.

Effects of general, specific and combined warm-up on explosive muscular performance

The purpose of this study was to compare the acute effects of general, specific and combined warm-up (WU) on explosive performance. Healthy male (n = 10) subjects participated in six WU protocols in a crossover randomized study design. Protocols were: passive rest (PR; 15 min of passive rest), running (Run; 5 min of running at 70% of maximum heart rate), stretching (STR; 5 min of static stretching exercise), jumping [Jump; 5 min of jumping exercises – 3x8 countermovement jumps (CMJ) and 3x8 drop jumps from 60 cm (DJ60)], and combined (COM; protocols Run+STR+Jump combined). Immediately before and after each WU, subjects were assessed for explosive concentric-only (i.e. squat jump – SJ), slow stretch-shortening cycle (i.e. CMJ), fast stretch-shortening cycle (i.e. DJ60) and contact time (CT) muscle performance. PR significantly reduced SJ performance (p =0.007). Run increased SJ (p =0.0001) and CMJ (p =0.002). STR increased CMJ (p =0.048). Specific WU (i.e. Jump) increased SJ (p =0.001), CMJ (p =0.028) and DJ60 (p =0.006) performance. COM increased CMJ performance (p =0.006). Jump was superior in SJ performance vs. PR (p =0.001). Jump reduced (p =0.03) CT in DJ60. In conclusion, general, specific and combined WU increase slow stretch-shortening cycle (SSC) muscle performance, but only specific WU increases fast SSC muscle performance. Therefore, to increase fast SSC performance, specific fast SSC muscle actions must be included during the WU.