SCS 6th Annual Meeting-EEVFA-11th International Congress of Biochemistry and Physiology of Exercise, Athens, Greece, 2023.

On behalf of the Strength and Conditioning Society (SCS) and the Hellenic Society of Biochemistry and Exercise Physiology (EEVFA), we are pleased to present the abstracts of the SCS 6th Annual Meeting and EEVFA-11th International Congress of Biochemistry and Physiology of Exercise. The event was held at the Hellenic Olympic Committee headquarters in Athens, Greece, on 19-22 October 2023, and comprised several invited sessions from international and national speakers on a variety of topics related to biochemistry and exercise physiology, strength and conditioning practices and their application to health, injury prevention and sports performance. These included strength training in high-performance sports, sport science and training-competition load management in elite environments, biochemistry and exercise physiology and prescription, nutrition and biomechanics, among others. The conference also included different practical workshops conducted by renowned academics and practitioners on eccentric training, change of direction ability and strength and power training in professional team-sports, and ergospirometry and exercise prescription in specific populations. Finally, the event disseminated up-to-date strength and conditioning research by providing practitioners and researchers with the opportunity to present their most recent findings. In this regard, all abstracts of the communications presented at the SCS 6th Annual Meeting-EEVFA-11th International Congress of Biochemistry and Physiology of Exercise can be found in this Conference Report.

Muscle Architecture Adaptations to Static Stretching Training: A Systematic Review with Meta-Analysis.

BACKGROUND: Long-term stretching of human skeletal muscles increases joint range of motion through altered stretch perception and decreased resistance to stretch. There is also some evidence that stretching induces changes in muscle morphology. However, research is limited and inconclusive. OBJECTIVE: To examine the effect of static stretching training on muscle architecture (i.e., fascicle length and fascicle angle, muscle thickness and cross-sectional area) in healthy participants. DESIGN: Systematic review and meta-analysis. METHODS: PubMed Central, Web of Science, Scopus, and SPORTDiscus were searched. Randomized controlled trials and controlled trials without randomization were included. No restrictions on language or date of publication were applied. Risk of bias was assessed using Cochrane RoB2 and ROBINS-I tools. Subgroup analyses and random-effects meta-regressions were also performed using total stretching volume and intensity as covariates. Quality of evidence was determined by GRADE analysis. RESULTS: From the 2946 records retrieved, 19 studies were included in the systematic review and meta-analysis (n = 467 participants). Risk of bias was low in 83.9% of all criteria. Confidence in cumulative evidence was high. Stretching training induces trivial increases in fascicle length at rest (SMD = 0.17; 95% CI 0.01-0.33; p = 0.042) and small increases in fascicle length during stretching (SMD = 0.39; 95% CI 0.05 to 0.74; p = 0.026). No increases were observed in fascicle angle or muscle thickness (p = 0.30 and p = 0.18, respectively). Subgroup analyses showed that fascicle length increased when high stretching volumes were used (p < 0.004), while no changes were found for low stretching volumes (p = 0.60; subgroup difference: p = 0.025). High stretching intensities induced fascicle length increases (p < 0.006), while low stretching intensities did not have an effect (p = 0.72; subgroup difference: p = 0.042). Also, high intensity stretching resulted in increased muscle thickness (p = 0.021). Meta-regression analyses showed that longitudinal fascicle growth was positively associated with stretching volume (p < 0.02) and intensity (p < 0.04). CONCLUSIONS: Static stretching training increases fascicle length at rest and during stretching in healthy participants. High, but not low, stretching volumes and intensities induce longitudinal fascicle growth, while high stretching intensities result in increased muscle thickness. REGISTRATION: PROSPERO, registration number: CRD42021289884.

The contralateral effects of foam rolling on range of motion and muscle performance.

A single bout of foam rolling (FR) can acutely increase joint range of motion (ROM) without detrimental effects on subsequent muscle performance. Similarly, long-term FR training can increase ROM, while muscle performance seems to be unaffected. Although the acute and long-term effects of FR on the treated muscle are understood, the impact of FR on the contralateral side is not well known. Therefore, this scoping review aims to summarize the current evidence on the acute and long-term effect of FR on the ipsilateral limb on ROM and muscle performance (i.e., maximum force, rate of force development, jump height) for the contralateral (non-treated) limb. Potential explanatory mechanisms are also discussed. There is evidence that a single bout of FR on the ipsilateral limb increases ROM of the contralateral limb; however, evidence is limited for long-term effects. The most likely mechanism for contralateral ROM increases is a reduced perception of pain. With regard to isolated muscle contractions, no changes in muscle performance (i.e., maximum voluntary isometric contraction, maximum voluntary dynamic contraction) were found in the contralateral limb after a single bout of FR on the ipsilateral limb. Notably, only one study reported large impairments in rate of force development of the contralateral limb following FR on the ipsilateral leg, possibly due to decreased motor unit recruitment. Furthermore, to date there are only two studies examining the long-term FR training of the ipsilateral limb on performance (i.e., maximal strength and jump performance) which reported moderate improvements. Although, trivial to very large changes on a variety of parameters were found in this study, the functional and practical relevance of our findings should be interpreted with caution.

Is There a "Window of Opportunity" for Flexibility Development in Youth? A Systematic Review with Meta-analysis.

BACKGROUND: Flexibility is an important component of physical fitness for competitive and recreational athletes. It is generally suggested that flexibility training should start from childhood (6-11 years of age) to optimize joint range of motion (ROM) increases; however, evidence is limited and inconsistent. OBJECTIVE: To examine whether there is a difference in the effect of stretching training on flexibility during childhood (6-11 years of age) and adolescence (12-18 years of age). DESIGN: Systematic review and meta-analysis. METHODS: We searched PubMed Central, Web of Science, Scopus, Embase, and SPORTDiscus, to conduct this systematic review. Randomized controlled trials and non-randomized controlled trials were eligible. No language and date of publication restrictions were applied. Risk of bias was assessed using Cochrane RoB2 and ROBINS-I tools. Meta-analyses were conducted via an inverse variance random-effects model. GRADE analysis was used to assess the methodological quality of the studies. RESULTS: From the 2713 records retrieved 28 studies were included in the meta-analysis (n = 1936 participants). Risk of bias was low in 56.9% of all criteria. Confidence in cumulative evidence was moderate. We found that stretching was effective in increasing ROM in both children (SMD = 1.09; 95% CI = 0.77-1.41; Z = 6.65; p < 0.001; I2 = 79%) and adolescents (SMD = 0.90; 95% CI = 0.70-1.10; Z = 8.88; p < 0.001; I2 = 81%), with no differences between children and adolescents in ROM improvements (p = 0.32; I2 = 0%). However, when stretching volume load was considered, children exhibited greater increases in ROM with higher than lower stretching volumes (SMD = 1.21; 95% CI = 0.82-1.60; Z = 6.09; p < 0.001; I2 = 82% and SMD = 0.62; 95% CI = 0.29-0.95; Z = 3.65; p < 0.001; I2 = 0%, respectively; subgroup difference: p = 0.02; I2 = 80.5%), while adolescents responded equally to higher and lower stretching volume loads (SMD = 0.90; 95% CI = 0.47-1.33; Z = 4.08; p < 0.001; I2 = 83%, and SMD = 0.90; 95% CI = 0.69-1.12; Z = 8.18; p < 0.001; I2 = 79%, respectively; subgroup difference: p = 0.98; I2 = 0%). CONCLUSIONS: Systematic stretching training increases ROM during both childhood and adolescence. However, larger ROM gains may be induced in childhood than in adolescence when higher stretching volume loads are applied, while adolescents respond equally to high and low stretching volume loads. REGISTRATION: INPLASY, registration number: INPLASY202190032; https://inplasy.com/inplasy-2021-9-0032/.

Foam Rolling Training Effects on Range of Motion: A Systematic Review and Meta-Analysis.

BACKGROUND: A single foam-rolling exercise can acutely increase the range of motion (ROM) of a joint. However, to date the adaptational effects of foam-rolling training over several weeks on joint ROM are not well understood. OBJECTIVE: The purpose of this meta-analysis was to investigate the effects of foam-rolling training interventions on joint ROM in healthy participants. METHODS: Results were assessed from 11 studies (either controlled trials [CT] or randomized controlled trials [RCTs]) and 46 effect sizes by applying a random-effect meta-analysis. Moreover, by applying a mixed-effect model, we performed subgroup analyses, which included comparisons of the intervention duration (≤ 4 weeks vs > 4 weeks), comparisons between muscles tested (e.g., hamstrings vs quadriceps vs triceps surae), and study designs (RCT vs CT). RESULTS: Our main analysis of 290 participants with a mean age of 23.9 (± 6.3 years) indicated a moderate effect of foam-rolling training on ROM increases in the experimental compared to the control group (ES = 0.823; Z = 3.237; 95% CI 0.325-1.322; p = 0.001; I2 = 72.76). Subgroup analyses revealed no significant differences between study designs (p = 0.36). However, a significant difference was observed in the intervention duration in favor of interventions > 4 weeks compared to ≤ 4 weeks for ROM increases (p = 0.049). Moreover, a further subgroup analysis showed significant differences between the muscles tested (p = 0.047) in the eligible studies. Foam rolling increased joint ROM when applied to hamstrings and quadriceps, while no improvement in ankle dorsiflexion was observed when foam rolling was applied to triceps surae. CONCLUSION: Longer duration interventions (> 4 weeks) are needed to induce ROM gains while there is evidence that responses are muscle or joint specific. Future research should examine possible mechanisms underpinning ROM increases following different foam-rolling protocols, to allow for informed recommendations in healthy and clinical populations.

Evaluation of The Isometric and Dynamic Rates of Force Development in Multi-Joint Muscle Actions.

The rate of force development (RFD) in the isometric leg press (ILP), the countermovement jump (CMJ) and the squat jump (SJ) were examined in twenty-three (9 females) team sport athletes aged 21-24 years. Peak force (Fpeak), peak rate of force development (RFDpeak) and RFD at different time epochs (0-50, 50-100, 100-150, 150-200) were calculated from the force-time curve, as well as CMJ and SJ height and the center of mass displacement. RFDpeak, RFD at 0-50, 50-100 and 100-150 ms and Fpeak were similar between the CMJ and the SJ (p = 0.26 to 0.99). Furthermore, RFD0-50 ms was similar between the ILP, the CMJ, and the SJ (p = 0.99 to 0.57). Higher values were observed in the ILP compared with the CMJ and the SJ in RFD50-100 ms and RFD100-150 ms (p < 0.001) and these differences were maintained even when RFD was scaled to body mass. The higher RFD normalized to Fpeak was attained at the 50-100 ms time interval with no differences between the ILP, CMJ and SJ and between males and females. These results suggest that the ability to exert rapid force is similar between the CMJ and the SJ, irrespective of the type of muscle action. Furthermore, RFD normalized to Fpeak is a muscle-force independent index of explosive force production, facilitating comparisons between individuals with different levels of muscle strength. The similarities between the CMJ and the SJ in RFDpeak, Fpeak, and RFD at different time epochs may imply that these types of jumps could be used interchangeably to assess explosive lower limb performance.

Weight Pressures and Eating Disorder Symptoms among Adolescent Female Gymnasts of Different Performance Levels in Greece.

This study examined the weight pressures within the gymnastics environment and explored associations between these pressures and eating disorder (ED) symptoms in adolescent female gymnasts. One hundred and forty-seven competitive gymnasts and 122 recreational-level gymnasts (11-17 years old) completed the Eating Attitudes Test (EAT-26), the Weight-Pressures in Sport-Females (WPS-F), the Social Desirability Scale (SDS) and provided information on their training. It was found that 16.3% of competitive gymnasts and 7.4% of non-competitive gymnasts scored ≥20 in EAT-26, indicating disordered eating behavior. Competitive gymnasts scored higher than non-competitive in the total score of EAT-26 (p = 0.027), as well as in the total score of WPS-F, the sport and coaches weight pressures sub-scale and the appearance and performance weight pressures sub-scale (p < 0.001). Multiple regression analyses indicated that sport and coaches weight pressures, appearance and performance weight pressures and body mass index accounted for 30.3% of the variance of EAT-26 in competitive gymnasts, while the appearance and performance weight pressures sub-scale accounted for 16.3% of the variance of EAT-26 in non-competitive gymnasts. Sport and coaches weight pressures are associated with ED in competitive gymnasts, while body appearance and performance demands correlate with ED in female gymnasts irrespective of competitive level.

Acute and long-term effects of two different static stretching training protocols on range of motion and vertical jump in preadolescent athletes.

This study examined the acute and long-term effects of two static stretching protocols of equal duration, performed either as a single stretch or multiple shorter duration repetitions on hip hyperextension range of motion (ROM) and single leg countermovement jump height (CMJ). Thirty female gymnasts were randomly assigned to stretching (SG) or control groups (CG). The SG performed two different protocols of static stretching, three times per week for 9 weeks. One leg performed repeated stretching (3 × 30 s with 30 s rest) while the other leg performed a single stretch (90 s). The CG continued regular training. ROM and CMJ were measured pre- and 2 min post-stretching on weeks 0, 3, 6, 9, and 3 weeks into detraining. CMJ height increased over time irrespective of group (main effect time, p = 0.001), with no statistical difference between groups (main effect group, p = 0.272). Three-way ANOVA showed that, CMJ height after stretching was not affected by either stretching protocol at any time point (p = 0.503 to 0.996). Both stretching protocols equally increased ROM on weeks 6 (10.9 ± 13.4%, p < 0.001, d = 0.42), and 9 (21.5 ± 13.4%, p < 0.001, d = 0.78), and this increase was maintained during detraining (17.0 ± 15.0%, p < 0.001, d = 0.68). No increase in ROM was observed in the CG (p > 0.874). Static stretching of long duration applied either as single or multiple bouts of equal duration, results in similar acute and long-term improvements in ROM. Furthermore, both stretching protocols do not acutely affect subsequent CMJ performance, and this effect is not influenced by the large increase in ROM and CMJ overtime.

Muscle Architectural and Functional Adaptations Following 12-Weeks of Stretching in Adolescent Female Athletes.

This study examined the effects of high-volume static stretching training on gastrocnemius muscle architecture, ankle angle and jump height in 21 female adolescent volleyball players. Static stretching of the plantar flexors of one leg (STR) was performed five times/week for 12 weeks, in addition to volleyball training, with the contra-lateral leg used as control (CON). Total duration of stretching per session increased from 540 s (week 1) to 900 s (week 12). At baseline, week 12 and after 3 weeks of detraining, muscle architecture at the middle and the distal part of both gastrocnemius heads (medialis and lateralis) and ankle angle were examined at rest and at maximum dorsiflexion. At the same time-points gastrocnemius cross-sectional area (CSA) was also assessed, while jumping height was measured at baseline and week 12. Following intervention, ankle dorsiflexion increased in both legs with a greater increase in STR than CON (22 ± 20% vs. 8 ± 17%, p < 0.001). Fascicle length at the middle part of gastrocnemius medialis increased only in the STR, at rest (6 ± 7%, p = 0.006) and at maximum dorsiflexion (11 ± 7%, p < 0.001). Fascicle length at maximum dorsiflexion also increased at the distal part of gastrocnemius lateralis of STR (15 ± 13%, p < 0.001). A greater increase in CSA (23 ± 14% vs. 13 ± 14%, p < 0.001) and in one-leg jumping height (27 ± 30% vs. 17 ± 23%, p < 0.001) was found in STR than CON. Changes in ankle angle, fascicle length and CSA were maintained following detraining. High-volume stretching training for 12 weeks results in ankle dorsiflexion, fascicle length and muscle cross sectional area increases in adolescent female volleyball players. These adaptations may partly explain improvements in jump performance.

Are they too perfect to eat healthy? Association between eating disorder symptoms and perfectionism in adolescent rhythmic gymnasts.

OBJECTIVE: Eating disorders are associated with perfectionism in adults, but evidence is lacking in adolescent competitive athletes. This study examined eating disorder symptoms and perfectionism in a sample of 13-15 years old, adolescent rhythmic gymnasts. METHODS: Eighty-nine female rhythmic gymnasts (41 international and 48 recreational level gymnasts), completed the Eating Attitudes Tests 26 (EAT-26), the Sport Perfectionism Questionnaire (SPQ), the Social Desirability Scale (SDS) and provided information on their training. RESULTS: It was found that 41.46% of the international and 14.58% of the recreational level gymnasts scored ≥20 in EAT-26. International level gymnasts also scored higher than recreational in EAT-26 (p = 0.002), and its subscales Dieting (p = 0.012) and Oral Control (p Ë‚ 0.001) and in the Sport Perfectionism Questionnaire (p = 0.005) and the subscales Striving for Perfectionism (p Ë‚ 0.001) and Personal Standards (p Ë‚ 0.001). No differences were found between groups in the subscales Concerns over Mistakes (p = 0.429), and Negative Reactions to Imperfection (p = 0.096). Multiple regression analysis in international level gymnasts, showed that Negative Reactions to Imperfection, body mass index and training experience accounted for 33.2% of the variance in EAT-26 (adjusted R2 = 0.332, F = 6.786, p Ë‚ 0.001). A negative association was observed between training experience and eating disorder symptoms in international level athletes. No association was found between the subscales of perfectionism and EAT-26 in recreational gymnasts (p Ëƒ 0.316). CONCLUSIONS: International level, adolescent rhythmic gymnasts show more eating pathology than recreational. Negative Reactions to Imperfection and BMI seem relevant for gymnasts' dieting behaviour while training experience may help adolescent athletes to cope with disturbed eating behaviours.

Effects of Supplementary Strength-Power Training on Neuromuscular Performance in Young Female Athletes.

This study examined the effects of a short-duration supplementary strength-power training program on neuromuscular performance and sport-specific skills in adolescent athletes. Twenty-three female "Gymnastics for All" athletes, aged 13 ± 2 years, were divided into a training group (TG, n = 12) and a control group (CG, n = 11). Both groups underwent a test battery before and after 10 weeks of intervention. TG completed, in addition to gymnastics training, a supplementary 7-9 min program that included two rounds of strength and power exercises for arms, torso, and legs, executed in a circuit fashion with 1 min rest between rounds, three times per week. Initially, six exercises were performed (15 s work-15 s rest), while the number of exercises was decreased to four and the duration of each exercise was increased to 30 s (30 s rest) after the fifth week. TG improved countermovement jump performance with one leg (11.5% ± 10.4%, p = 0.002) and two legs (8.2% ± 8.8%, p = 0.004), drop jump performance (14.4% ± 12.6%, p = 0.038), single-leg jumping agility (13.6% ± 5.2%, p = 0.001), and sport-specific performance (8.8% ± 7.4%, p = 0.004), but not 10 m sprint performance (2.4% ± 6.6%, p = 0.709). No change was observed in the CG (p = 0.41 to 0.97). The results of this study indicated that this supplementary strength-power program performed for 7-9 min improves neuromuscular and sport-specific performance after 10 weeks of training.

Heart Rate Responses during Sport-Specific High-Intensity Circuit Exercise in Child Female Gymnasts.

This study examined heart rate (HR) responses during a sport-specific high-intensity circuit training session to indirectly assess cardiorespiratory stress in child athletes. Seventeen, female gymnasts, aged 9-11 years performed two 5-min 15 s sets of circuit exercise, interspersed by a 3 min rest interval. Each set included five rounds of five gymnastic exercises (7 s work, 7 s rest) executed with maximal effort. During the first circuit training set, peak heart rate (HR) was 192 ± 7 bpm and average HR was 83 ± 4% of maximum HR (HRmax), which was determined in a separate session. In the second set, peak HR and average HR were increased to 196 ± 8 bpm (p < 0.001, d = 0.55) and to 89 ± 4% HRmax (p < 0.001, d = 2.19), respectively, compared with the first set. HR was above 80% HRmax for 4.1 ± 1.2 min during set 1 and this was increased to 5.1 ± 0.4 min in set 2 (p < 0.001, d = 1.15). Likewise, HR was above 90% of HRmax for 2.0 ± 1.2 min in set 1 and was increased to 3.4 ± 1.7 min in set 2 (p < 0.001, d = 0.98). In summary, two 5-min 15 s sets of high-intensity circuit training using sport-specific exercises, increased HR to levels above 80% and 90% HRmax for extended time periods, and thus may be considered as an appropriate stimulus, in terms of intensity, for improving aerobic fitness in child female gymnasts.

Gastrocnemius Medialis Architectural Properties in Flexibility Trained and Not Trained Child Female Athletes: A Pilot Study.

Gastrocnemius medialis (GM) architecture and ankle angle were compared between flexibility trained (n = 10) and not trained (n = 6) female athletes, aged 8-10 years. Ankle angle, fascicle length, pennation angle and muscle thickness were measured at the mid-belly and the distal part of GM, at rest and at the end of one min of static stretching. Flexibility trained (FT) and not trained athletes (FNT) had similar fascicle length at the medial (4.19 ± 0.37 vs. 4.24 ± 0.54 cm, respectively, p = 0.841) and the distal part of GM (4.25 ± 0.35 vs. 4.18 ± 0.65 cm, respectively, p = 0.780), similar pennation angles, and muscle thickness (p > 0.216), and larger ankle angle at rest (120.9 ± 4.2 vs. 110.9 ± 5.8°, respectively, p = 0.001). During stretching, FT displayed greater fascicle elongation compared to FNT at the medial (+1.67 ± 0.37 vs. +1.28 ± 0.22 cm, respectively, p = 0.048) and the distal part (+1.84 ± 0.67 vs. +0.97 ± 0.97 cm, respectively, p = 0.013), larger change in joint angle and muscle tendon junction displacement (MTJ) (p < 0.001). Muscle thickness was similar in both groups (p > 0.053). Ankle dorsiflexion angle significantly correlated with fascicle elongation at the distal part of GM (r = -0.638, p < 0.01) and MTJ displacement (r = -0.610, p < 0.05). Collectively, FT had greater fascicle elongation at the medial and distal part of GM and greater MTJ displacement during stretching than FNT of similar age.

Acute Effects of Intermittent and Continuous Static Stretching on Hip Flexion Angle in Athletes with Varying Flexibility Training Background.

Τhis study examined changes in hip joint flexion angle after an intermittent or a continuous static stretching protocol of equal total duration. Twenty-seven female subjects aged 19.9 ± 3.0 years (14 artistic and rhythmic gymnasts and 13 team sports athletes), performed 3 min of intermittent (6 × 30 s with 30 s rest) or continuous static stretching (3 min) of the hip extensors, with an intensity of 80-90 on a 100-point visual analogue scale. The order of stretching was randomized and counterbalanced, and each subject performed both conditions. Hip flexion angle was measured with the straight leg raise test for both legs after warm-up and immediately after stretching. Both stretching types equally increased hip flexion angle by ~6% (continuous: 140.9° ± 20.4° to 148.6° ± 18.8°, p = 0.047; intermittent: 141.8° ± 20.3° to 150.0° ± 18.8°, p = 0.029) in artistic and rhythmic gymnasts. In contrast, in team sports athletes, only intermittent stretching increased hip flexion angle by 13% (from 91.0° ± 7.2° to 102.4° ± 14.5°, p = 0.001), while continuous stretching did not affect hip angle (from 92.4° ± 6.9° vs. 93.1° ± 9.2°, p = 0.99). The different effect of intermittent vs. continuous stretching on hip flexion between gymnasts and team sports athletes suggests that responses to static stretching are dependent on stretching mode and participants training experience.

Effect of Plyometric Training on Jumping, Sprinting and Change of Direction Speed in Child Female Athletes.

BACKGROUND: This study examined the effects of 8 weeks of plyometric training on jumping, sprinting, and change of direction (COD) performance. METHODS: Fifty female 7-9-year-old gymnasts were randomly assigned to a plyometric training group (PG; n = 33), that performed supplementary plyometric training twice per week, and a control group (CG; n = 17) that continued regular training. The following tests were performed before and after the intervention: 10 and 20 m sprints, 5 + 5 m and 10 + 10 m COD tests, one-leg and two-leg countermovement jump (CMJ), drop jump (DJ), squat jump (SJ), and standing long jump (SLJ). RESULTS: Only a main effect for time was found for all jumping performance parameters (p = 0.001). However, the improvement of one- and two-leg CMJ in PG had a greater effect size than CG (0.72 and 0.67 vs. 0.34 and 0.18, respectively). Group × time interactions were found for 10 and 20 m sprint tests (p = 0.018 and p = 0.011, respectively) and for 10 + 10 m COD (p = 0.008) with the post hoc test showing improvement only for the PG (p = 0.001, 0.001, and 0.003 and d = 1.1, 1.14, and 0.6, respectively). CONCLUSIONS: Supplementary plyometric training increased sprint and COD performance more than regular gymnastics training, while jumping performance was equally improved in both groups.

Gastrocnemius Medialis Architectural Properties at Rest and During Stretching in Female Athletes with Different Flexibility Training Background.

BACKGROUND: This study examined gastrocnemius medialis (GM) architectural properties and ankle joint range of motion (ROM) between female athletes with different flexibility training background. METHODS: Elite rhythmic gymnasts (n = 10) were compared to national level volleyball athletes (n = 10). Fascicle length, pennation angle and muscle thickness at the medial and the distal part of GM, and ankle ROM were measured at rest and during 1 min of static stretching. RESULTS: At rest, rhythmic gymnasts displayed longer fascicles compared to volleyball athletes, at the medial (5.93 ± 0.27 vs. 4.74 ± 0.33 mm, respectively, p = 0.001) and the distal part of GM (5.63 ± 0.52 vs. 4.57 ± 0.51 mm, respectively, p = 0.001), smaller pennation angle at the medial part (22.4 ± 2.5 vs. 25.8 ± 2.4°; respectively, p = 0.001) and greater ankle angle (121.7 ± 4.1 vs. 113.2 ± 3.7°, respectively, p = 0.001). During the 1 min of static stretching, gymnasts displayed greater fascicle elongation at the distal part (p = 0.026), greater maximal ankle dorsiflexion (p < 0.001) and muscle tendon junction displacement (p < 0.001) with no difference between groups in pennation angles (p > 0.145), muscle thickness (p > 0.105), and fascicle elongation at mid-belly (p = 0.063). CONCLUSIONS: Longer muscle fascicles at rest and greater fascicle elongation at the distal part of GM may contribute to the greater ankle ROM observed in rhythmic gymnasts.

Intermittent but Not Continuous Static Stretching Improves Subsequent Vertical Jump Performance in Flexibility-Trained Athletes.

Bogdanis, GC, Donti, O, Tsolakis, C, Smilios, I, and Bishop, DJ. Intermittent but not continuous static stretching improves subsequent vertical jump performance in flexibility-trained athletes. J Strength Cond Res 33(1): 203-210, 2019-This study examined changes in countermovement jump (CMJ) height after an intermittent or a continuous static stretching protocol of equal total duration. Sixteen male, elite-level gymnasts performed 90 seconds of intermittent (3 × 30 seconds with 30 seconds rest) or continuous stretching (90 seconds) of the quadriceps muscle. A single-leg stretching and jumping design was used, with the contralateral limb serving as a control. The same individuals performed both conditions with alternate legs in a randomized, counterbalanced order. One-leg CMJ height was measured for the stretched and the control leg after warm-up, immediately after stretching, and at regular intervals for 10 minutes after stretching. Range of motion (ROM) of the hip and knee joints was measured before, after, and 10 minutes poststretching. Compared with the control leg, intermittent stretching increased CMJ height by 8.1 ± 2.0%, 4 minutes into recovery (2.2 ± 2.0 cm, 95% confidence interval [CI]: 1.0-3.4 cm, p = 0.001), whereas continuous stretching decreased CMJ height by 17.5 ± 3.3% immediately after (-2.9 ± 1.7 cm, 95% CI: -2.0 to -3.7 cm, p = 0.001) and by 12.0 ± 2.7% 1 minute after stretching (-2.2 ± 2.1 cm, 95% CI: -1.2 to -3.2 cm, p = 0.001). The increases in hip (2.9 and 3.6°, p = 0.001. d = 2.4) and knee joint ROM (5.1 and 6.1°, p = 0.001. d = 0.85) after the intermittent and continuous stretching protocols were not different. The opposite effects of intermittent vs. continuous stretching on subsequent CMJ performance suggests that stretching mode is an important variable when examining the acute effects of static stretching on performance in flexibility-trained athletes.

Obesity and physical fitness indices of children aged 5-12 years living on remote and isolated islands.

INTRODUCTION: Obesity has become one of the major health risks in childhood, significantly affecting children's health and physical fitness. Although the marked increase of obesity in urban areas is well established, evidence is limited in remote and isolated areas with adverse socioeconomic features. The aim of this study was to examine the prevalence of obesity and its association with physical performance indices in young school-aged children living in 18 remote and isolated Greek islands. METHODS: Four hundred and sixty-three children (244 boys, 219 girls), aged 5-12 years underwent a series of physical fitness tests including 20 m sprint, standing long jump, 1 kg medicine ball throw, agility T-test and sit-and-reach test. Age and gender BMI cut-off points were determined according to World Health Organisation (WHO) norms. RESULTS: The prevalence of obesity was 23.8% and 13.2% for boys and girls, respectively. A negative body mass index (BMI) main effect was observed for weight-bearing activities, such as 20 m sprint (F=6.21, p=0.000, η2=0.041) and standing long jump (F=11.369, p=0.000, η2=0.074), while medicine ball throw was positively correlated with BMI in children aged 9-12 years. CONCLUSION: The results of this study confirmed previous findings on obesity prevalence in Greece. A negative association was also found between BMI and physical fitness indices and, in particular, in weight-bearing activities. It is critical to establish physical education interventions and physical fitness programs at schools, aiming to increase motivation for physical activity participation.

The relative contribution of physical fitness to the technical execution score in youth rhythmic gymnastics.

This study examined the association between physical fitness and a technical execution score in rhythmic gymnasts varying in the performance level. Forty-six young rhythmic gymnasts (age: 9.9 ±1.3 years) were divided into two groups (qualifiers, n=24 and non-qualifiers, n=22) based on the results of the National Championships. Gymnasts underwent a series of physical fitness tests and technical execution was evaluated in a routine without apparatus. There were significant differences between qualifiers and non-qualifiers in the technical execution score (p=0.01, d=1.0), shoulder flexion (p=0.01, d=0.8), straight leg raise (p=0.004, d=0.9), sideways leg extension (p=0.002, d=0.9) and body fat (p=.021, d=0.7), but no differences were found in muscular endurance and jumping performance. The technical execution score for the non-qualifiers was significantly correlated with shoulder extension (r=0.423, p<0.05), sideways leg extension (r=0.687, p<0.01), push ups (r=0.437, p<0.05) and body fat (r=0.642, p<0.01), while there was only one significant correlation with sideways leg extension (r=0.467, p<0.05) for the qualifiers. Multiple regression analysis revealed that sideways leg extension, body fat, and push ups accounted for a large part (62.9%) of the variance in the technical execution score for the non-qualifiers, while for the qualifiers, only 37.3% of the variance in the technical execution score was accounted for by sideways leg extension and spine flexibility. In conclusion, flexibility and body composition can effectively discriminate between qualifiers and non-qualifiers in youth rhythmic gymnastics. At the lower level of performance (non-qualifiers), physical fitness seems to have a greater effect on the technical execution score.

Effects of baseline levels of flexibility and vertical jump ability on performance following different volumes of static stretching and potentiating exercises in elite gymnasts.

This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warm- up protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes. Key PointsThe initial levels of flexibility and vertical jump ability have no effect on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) of elite gymnasts following warm-up protocols differing in stretching and potentiating exercise volumesStretching of the main leg muscle groups for only 15 s has no effect on ROM of elite gymnastsIn these highly-trained athletes, one set of 5 tuck jumps during warm-up is not adequate to increase CMJ performance, while 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance (by 4.6% above baseline), despite a 5.9% increase in flexibility due to the 30 s stretching exercises.