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Osteogenesis with impact-loading exercise is often assessed by the extra bone growth induced in the loaded arm of tennis players. We used PRISMA to explore % bone mineral content (BMC) and area (BA) asymmetry in players 8-30 years according to weekly training hours, age, sex, maturity, and bone segment. Proper statistics for 70 groups were extracted by two reviewers from 18 eligible studies of low risk of bias (< 35, STROBE) and good quality (> 70%). The quality of the review was high (AMSTAR, 81%). Using "random effects" we tested moderation-specific meta-comparisons and meta-regressions. The loaded bones % hypertrophy was higher in BMC (19%) than BA (10%), and, with BMC and BA merged, in boys (17%) than girls (13%), in humerus (19%) than radius-ulna (14%), and in pubertal (19%) players. Weekly training hours were more important (43%) than sex (17%), puberty (14%) and bone (15%) in BMC, and puberty (48%) was more important than weekly training hours (19%), sex (12%), and radius-ulna (5%) in BA. The loaded bones % hypertrophy correlated with weekly training hours highly (> 0.60) in all maturity groups for BMC and BA, and moderately (0.41) in early adults for BA; it also correlated with age (≥ 0.60) in children and peripubertal players, but not (0.037) with starting age. Impact loading exercise favors mineralization twice than bone expansion, while puberty favors bone expansion about three times more than mineralization. The bone gains are higher for boys than girls, and for peripubertal than older players. The bone growth implications are discussed considering limitations and future research., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

North Africa is among the most water-stressed regions in the world; still, the habitat requirements of its freshwater biota are largely unknown. In this study, (i) we developed habitat suitability curves (HSCs) for freshwater macroinvertebrates in two poorly studied, regulated North African rivers (Ziz and Oum Er-Rbia), and (ii) assessed environmental flows downstream of each river dam by incorporating the HSCs in two-dimensional ecohydraulic models. We demonstrate a low-cost sampling methodology combined with freely distributed ecohydraulic modeling software. The results showed that macroinvertebrates in the arid-desert Ziz River could tolerate a wide range of habitats in terms of flow velocity and water depth compared to the arid-steppe Oum Er-Rbia River, probably due to their adaptation to extreme (arid-desert) environmental conditions. Optimal environmental flows downstream of the Al Hassan Addakhil (Ziz River) and the Al Massira (Oum Er-Rbia River) dams were 1 m 3 /s and 2 m 3 /s, respectively. However, environmental flows at 0.5 m 3 /s and 1 m 3 /s, respectively, could still maintain sustainable freshwater biota downstream of the dams. The results further highlight the critical status of the Ziz River, which was completely dry, and the alarming status of the Oum Er-Rbia River due to the significant reduction in the water levels of the Al Massira Dam. In a continuously changing climate, we suggest that the proposed environmental flows should be immediately delivered to prevent droughts and ensure healthy freshwater communities downstream of the dams, within a basin-wide freshwater management framework. In this water scarce region, more research is necessary to increase ecological awareness about these understudied freshwater systems and achieve a balance between human needs and ecosystem requirements., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Knowledge of uncertainty is valuable mainly in correctly appraising measured effects. In lower limb stiffness, which affects injury risk and athletic performance, uncertainty is often related to vertical (K vert ) and leg (K leg ) stiffness. Imprecisions in measurements of body mass (M), leg length (L), contact (t c ) and flight (t f ) time propagate through the calculations, augment stiffness uncertainty and inflate relevant effects. This study estimated the limits of this uncertainty as probable (E prob ) and upper bound (E upper ) errors by applying Taylor series expansion on Monte-Carlo simulated data. E prob and E upper were 1285 ± 221 N/m (3.9 ± 0.2%) and 1441 ± 248 N/m (4.4 ± 0.3%) in K vert , and 222 ± 61 N/m (2.1 ± 0.1%) and 375 ± 109 N/m (3.6 ± 0.3%) in K leg , respectively. To avoid the complexities of full Taylor series expansion, E prob was predicted (R 2  ≈ 1) more simply as 0.89E upper in K vert and 11 + 0.56E upper in K leg . These uncertainties reflect mostly errors in t c and t f , and uncertainty in F max , at kinematic sampling of 300 Hz and running at 4-5 m/s. With slower sampling or faster running these uncertainties rise, and their impact on similar lower limb stiffness effects could be substantial. Applying Taylor series expansion for error propagation on Monte-Carlo simulated data is valid for uncertainty analysis in any multivariable functional relationship.

Purpose: Bone growth with exercise is best assessed by tennis-induced inter-arm asymmetries. Yet, the effects of training and maturation across puberty were unclear. This study explored arm bone growth across 9 months of training in 46 tennis players 7-14 years (25 boys, 21 girls)., Methods: Bone mineral content (BMC) and bone area (BA) were measured from DXA scans. Pubertal status was assessed by Tanner stage (TS) and somatic growth by maturity offset (MO). Children were grouped as pre- (TS I-I), early (TS I-II), and mid/late pubertal (TS II-III)., Results: Training time (TT) change in the three groups was 160-170, 190-230, and 200-220 h, respectively. Bone asymmetries were large in all groups (d > 0.8, P < 0.001): 5-18 g (9-21%) and 9-17 g (17-23%) in girls and boys, respectively, for BMC, and 5-15 cm 2 (6-13%) and 9-15 cm 2 (12-15%) in girls and boys (10-13%), respectively, for BA. BMC and BA change asymmetry peaked at pre-puberty in girls (56%, 46%) and at early puberty in boys (57%, 43%). Asymmetry gains varied with baseline asymmetry (41%) and change in TT (38%) and TS (17%) in BMC, and with baseline asymmetry (58%) and change in MO (17%) and TS (12%) in BA., Conclusion: All bone asymmetries were substantial. Tennis-induced bone gains were higher at pre- to early puberty in girls and at early to mid/late puberty in boys. Training enhanced mostly bone mass and maturity status enhanced mostly bone size; sex was not bone-change modeling impactful. Implications are discussed considering certain limitations., (© 2024. The Author(s).)

The ocean is dynamically changing due to the influence of climate processes and human activities. The construction of the Suez Canal in the late nineteenth century opened the Pandora's box by facilitating the dispersal of Red Sea species in the Mediterranean Sea. In this study, we developed an open-source spatio-temporal numerical analysis framework to decodify the complex spread of Mediterranean non-indigenous fish species (NIS) that entered through the Suez Canal. We utilized 772 historical detection records of 130 NIS to disentangle their dynamic spread through space and time. The results indicated that species follow a north-westward trajectory with an average expansion time step of 2.5 years. Additionally, we estimated the overall time for a NIS to reach the Central Mediterranean Sea from the Suez Canal at approximately 22 years. Based on the analysis, more than half of the introduced fishes have been established in less than 10 years. Finally, we proceeded in the cross-validation of our results using actual spread patterns of invasive fishes of the Mediterranean Sea, resulting up to 90% of temporal and spatial agreement. The methodology and the findings presented herein may contribute to management initiatives in highly invaded regions around the globe., (© 2024. The Author(s).)

This study estimated upper and lower limb bone mineral content (BMC) and bone area (BA) in 48 children tennis players (24 boys, 24 girls) aged 7-13 years. The sample comprised four age groups (8.2 ± 0.44, 9.5 ± 0.13, 10.5 ± 0.33, 12.2 ± 0.58). BMC and BA were measured via DXA, and sexual maturity by the Tanner scale, then used as a binary: prepubertal vs peripubertal. Total training time (TTT) included all playing years. Arms were asymmetric and legs symmetric. Boys were more asymmetric than girls in BMC (18% vs 13%) and BA (11% vs 8%). Pre-pubertal children were less asymmetric than peri-pubertal in BMC (14% vs 18%) and in BA (9.4% vs 10%). Bone growth changed with age and TTT markedly better in the dominant arm. The linear combination of TTT, sex, and maturity binary extracted 59% of BMC asymmetry and only 21% of BA asymmetry. For both bone parameters the sex effect was significant only for the pre-pubertal children. Training time constitutes the best predictor of bone asymmetry compared to age, sex, and maturity; when adequate, playing arm bone hypertrophy may be detectable at the age of 7-8 years. These results have health and performance implications.

This study investigated the relationship between somatotype, level of competition, and performance in attack in elite level male volleyball players. The objective was to test for the potential covariation of competition level (Division A1 vs. A2) and playing position (hitters vs. centers vs. opposites) considering performance in attack. Anthropometric, body composition and somatotype variables were measured according to the Heath-Carter method. The attack actions of 144 players from 48 volleyball matches were analyzed and their performance was rated using a 5-point numerical scale. Results showed that players of Division A1 were taller, heavier, more muscular, and less endomorphic compared to those of Division A2. MANOVA and follow-up discriminant function analysis revealed somatotype differences among playing positions with centers and opposites being endomorph-ectomorph and hitters being central. Centers performed constantly better than hitters and opposites regardless of the division and somatotype. Multiple linear regression analysis showed that variables defining ectomorph and endomorph players, centers, and players of Division A1 significantly determined the relative performance superiority and were able to explain the variation in performance by almost 25%. These results could be taken into account by coaches when assigning players to particular playing positions or when designing individualized position-specific training programs.

The fatiguing effect of long-distance running has been examined in the context of a variety of parameters. However, there is scarcity of data regarding its effect on the vertical jump mechanics. The purpose of this study was to investigate the alterations of countermovement jump (CMJ) mechanics after a half-marathon mountain race. Twenty-seven runners performed CMJs before the race (Pre), immediately after the race (Post 1) and five minutes after Post 1 (Post 2). Instantaneous and ensemble-average analysis focused on jump height and, the maximum peaks and time-to-maximum peaks of: Displacement, vertical force (Fz), anterior-posterior force (Fx), Velocity and Power, in the eccentric (tECC) and concentric (tCON) phase of the jump, respectively. Repeated measures ANOVAs were used for statistical analysis (p ≤ 0.05). The jump height decrease was significant in Post 2 (-7.9%) but not in Post 1 (-4.1%). Fx and Velocity decreased significantly in both Post 1 (only in tECC) and Post 2 (both tECC and tCON). Α timing shift of the Fz peaks (earlier during tECC and later during tCON) and altered relative peak times (only in tECC) were also observed. Ensemble-average analysis revealed several time intervals of significant post-race alterations and a timing shift in the Fz-Velocity loop. An overall trend of lowered post-race jump output and mechanics was characterised by altered jump timing, restricted anterior-posterior movement and altered force-velocity relations. The specificity of mountain running fatigue to eccentric muscle work, appears to be reflected in the different time order of the post-race reductions, with the eccentric phase reductions preceding those of the concentric one. Thus, those who engage in mountain running should particularly consider downhill training to optimise eccentric muscular action. Key pointsThe 4.1% reduction of jump height immediately after the race is not statistically significantThe eccentric phase alterations of jump mechanics precede those of the concentric ones.Force-velocity alterations present a timing shift rather than a change in force or velocity magnitude.

The assessment of dietary attitudes and behaviors provides information of interest to sports nutritionists. Although there has been little analysis of the quality of research undertaken in this field, there is evidence of a number of flaws and methodological concerns in some of the studies in the available literature. This review undertook a systematic assessment of the attributes of research assessing the nutritional knowledge and attitudes of athletes and coaches. Sixty questionnaire-based studies were identified by a search of official databases using specific key terms with subsequent analysis by certain inclusion-exclusion criteria. These studies were then analyzed using 33 research quality criteria related to the methods, questionnaires, and statistics used. We found that many studies did not provide information on critical issues such as research hypotheses (92%), the gaining of ethics approval (50%) or informed consent (35%), or acknowledgment of limitations in the implementation of studies or interpretation of data (72%). Many of the samples were nonprobabilistic (85%) and rather small (42%). Many questionnaires were of unknown origin (30%), validity (72%), and reliability (70%) and resulted in low (≤ 60%) response rates (38%). Pilot testing was not undertaken in 67% of the studies. Few studies dealt with sample size (2%), power (3%), assumptions (7%), confidence intervals (3%), or effect sizes (3%). Improving some of these problems and deficits may enhance future research in this field.

Biomechanical findings show that running is asymmetric in many kinetic properties. Running stiffness is a vital kinetic property of yet unknown pattern of lateralization. The aim of this study was to examine the degree and variability of lower limb dominance specific asymmetry of running in terms of leg stiffness, vertical stiffness, contact time, flight time, maximal ground reaction force during contact, vertical displacement of the center of mass, and change in leg length. Leg and vertical stiffness was estimated by the sine-wave method in 22 young males during treadmill running at 4.44 m/s. Lower limb dominance was determined by the triple-jump test. Asymmetry was expressed as dominant - non-dominant, and indexed by the absolute asymmetry index. Significant asymmetry was found only in flight time (3.98%) and in maximal ground reaction force (1.75%). The absolute asymmetry index ranged from 1.8% to 6.4%, showed high variation between subjects (0-31.6%), and differentiated among the 7 analyzed variables. Leg and vertical stiffness in treadmill running of moderate pace (4.44 m/s) should be considered symmetric., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Overweight and obesity are widespread nutritional disorders. Their treatment aims at effective weight loss (WL) and weight loss maintenance (WLM). Previous systematic reviews show weight regain, after recommended exercise and diet combined. However, certain experimental and methodological inconsistencies in the original studies and in these reviews left space for a substantial revisit of this problem. This study aimed at systematically re-reviewing the effectiveness of exercise combined with diet on WLM in overweight and obese adults. Literature was searched through Embase and Sport Discus (up to 2008), and PubMed (Medline) and ISI Web of science (up to 2012). 14 randomized clinical trials (RCT) were retained, their quality was assessed by the Jadad scale, and detailed methodological and statistical characteristics were evaluated. Overall estimations showed a WL of 11.1 kg (about 13%) after an average of about 4 months from baseline, a WLM of 5.8 kg (about 52%) and a weight regain of 5.1 kg after an average period of about 21 months. WL was successful but almost half of it (about 48%) was regained, which agrees with previous findings. The Jadad score showed very good to excellent quality for all 14 studies. However, further assessment revealed serious weakness such as high average dropout (>20%), not estimating experimental power or not using a control group in more than half of the studies, possible lack of adherence and variability in demographic traits. Future studies may focus on improving these limitations for more accurate results in this crucial research field.

Objectives: Joint hypermobility syndrome (JHS) is a heritable disorder of the connective tissue characterized by excessive joint movement, musculoskeletal pain and neurophysiological deficits (i.e. decreased proprioceptive acuity, altered neuromuscular reflexes). Such deficits may affect body balance thus increasing the risk of injury. The present study aimed at examining static and dynamic body balance following challenge of the visual and vestibular systems in individuals with JHS., Methods: The sample consisted of 21 females with JHS and 20 controls without signs of JHS. Static body balance was assessed by the degree of anteroposterior and mediolateral deviation of the center of pressure, during 20-sec single-leg stances with eyes opened (EO), eyes closed (EC) and eyes opened with head extension (EO-HE) using a foot pressure platform. Dynamic body balance was assessed by the number of landing and balance errors committed during a multiple single-leg-hop-stabilization test., Results: Nonparametric analysis showed that the JHS-group demonstrated significantly greater (a) mediolateral deviation during single-leg-stance with EO (p < 0.01), (b) mediolateral and anteroposterior deviation during single-leg-stance with EO-HE (p < 0.05), and (c) number of landing errors (p < 0.05) compared to the control group., Conclusions: Poor static balance following challenge of the vestibular system may be justified by vestibular deficiency and/or insufficient proprioceptive capabilities of the neck. Impairments of dynamic balance in individuals with JHS may be attributed to proprioceptive deficits, which can alter feedforward and feedback mechanisms., (Copyright © 2013. Published by Elsevier Ltd.)

Background: Ankle sprain is an extremely common injury in soccer players. Despite extensive research, the intrinsic cause of this injury under noncontact conditions remains unclear., Purpose: To identify intrinsic risk factors for noncontact ankle sprains in professional soccer players., Study Design: Cohort study; Level of evidence, 2, Methods: One hundred professional soccer players were assessed in the preseason for potential risk factors of noncontact ankle sprains. The assessment included (A) ankle joint asymmetries (right-left) in isokinetic muscle strength, flexibility, proprioception, and stability; (B) somatometric asymmetries; (C) previous injuries; and (D) lateral dominance traits. Noncontact ankle sprains were prospectively recorded and diagnosed for a full competition period (10 months)., Results: Seventeen of the players sustained at least 1 noncontact ankle sprain. Logistic regression revealed that players with (A) eccentric isokinetic ankle flexion strength asymmetries (odds ratio [OR] = 8.88; 95% confidence interval [CI], 1.95-40.36, P = .005), (B) increased body mass index (OR = 8.16; 95% CI, 1.42-46.63, P = .018), and (C) increased body weight (OR = 5.72; 95% CI, 1.37-23.95, P = .017 ) each had a significantly higher risk of a noncontact ankle sprain. A trend for younger players (OR = 0.28; 95% CI, 0.061-1.24, P = .092) and for players with ankle laxity asymmetries (OR = 3.38; 95% CI, 0.82-14.00, P = .093) to be at greater risk for ankle sprain was also apparent to the limit of statistical significance (.05 < P < .10)., Conclusion: Functional strength asymmetries of the ankle flexors and increased body mass index and body weight raise the propensity for ankle sprains in professional soccer players. Age and asymmetries in ankle laxity are potential factors worth revisiting, as there was an indication for younger players and players with ankle instability to be at higher risk for ankle injury. Proper preseason evaluation may improve prevention strategies for this type of injury in soccer.

Objectives: To identify the intrinsic risk factors of non-contact strains in the hamstrings and quadriceps muscles of professional soccer players via a cohort prospective design., Methods: A total of 100 professional soccer players (aged 19.4-27.8 years) from four professional teams underwent a composite musculoskeletal assessment at preseason. Intrinsic risk factors included dichotomies of asymmetries in muscle strength, flexibility, proprioception, anthropometry and knee joint stability, and of previous injuries. Muscle strains were prospectively monitored during the subsequent season using questionnaires. The data were analysed via binary logistic regression., Results: Thirty-eight percent of the players sustained one or more lower-extremity muscle strains. Sixteen (42.1 %) and seven (18.4 %) of them were clinically diagnosed as having non-contact muscle strains at their hamstrings and quadriceps, respectively. Players with eccentric hamstring strength asymmetries (OR=3.88; 95% CI 1.13 to 13.23), functional leg length asymmetries (OR=3.80; 95% CI 1.08 to 13.33) and no previous hamstrings injuries (OR=0.15; 95% CI 0.029 to 0.79) were at greater risk of sustaining a hamstring muscle strain. Players with eccentric strength (OR=5.01; 95% CI 0.92 to 27.14) and flexibility asymmetries (OR=4.98; 95% CI 0.78 to 31.80) in their quadriceps as well as heavier (OR=10.70; 95% CI 0.73 to 156.37) and shorter players (OR=0.08; 95% CI 0.00 to 1.35) were at greater risk of sustaining a strain in this muscle group., Conclusions: Professional soccer players with functional asymmetries possess a higher risk of sustaining hamstring strains. Previous injury seems not to constitute a risk factor. The systematic isokinetic evaluation of the lower extremities during the preseason period can provide therapists and trainers with valuable data regarding the predictive elements of non-contact hamstring strains in professional soccer players.

Aim: Soccer players possess various degrees of functional footedness. Their lower limbs are subjected to consistent asymmetrical workloads and neuromuscular adaptations, and as a result develop asymmetrical patterns of musculoskeletal function. This study focused on the myodynamic profile of the knee and ankle joint in professional soccer players. Special emphasis was put on the multivariate quantification of three types of asymmetry: directional (left vs. right), fluctuating (dominant vs. non dominant) and absolute (left vs. right)., Methods: One-hundred professional soccer players (mean age 23.4 years, weight 73.3, height 177.6) were tested isokinetically for concentric and eccentric isokinetic muscle strength (1) of the knee flexors and extensors, and (2) of the ankle dorsal and plantar flexors. Knee flexion-extension was tested at 60o, 180o and 300o/s for the concentric mode of contraction and at 60o and 180o/s for the eccentric. The ankle joint was tested only at 60o/s for both the concentric and eccentric action., Results: MANOVA showed significances for all three types of strength asymmetry (joint and action combined): directional (Wilks' Λ=0.66, F=2.957, P=0.001), fluctuating (Wilks' Λ=0.61, F=2.957, P=0.007), and absolute asymmetry (Wilks' Λ=0.47, F=116.26, P=0.000). Several significant asymmetries were also revealed at the univariate level of analysis (P<0.05)., Conclusion: It seems that the lower limbs of professional soccer players are characterized by significant compound muscle strength asymmetries. These findings substantiate the idea of asymmetry in the myodynamic adaptations that take place at the knee and ankle joint of soccer players during the game. Individual modification of the training load, targeting in strength asymmetry correction, should be taken into consideration for injury prevention.

Kicking and cutting skills in soccer are clearly unilateral, require asymmetrical motor patterns and lead to the development of asymmetrical adaptations in the musculoskeletal function of the lower limbs. Assuming that these adaptations constitute a chronicity-dependent process, this study examined the effects of professional training age (PTA) on the composite strength profile of the knee and ankle joint in soccer players. One hundred soccer players (n=100) with short (5-7 years), intermediate (8-10 years) and long (>11 years) PTA were tested bilaterally for isokinetic concentric and eccentric strength of the knee and ankle muscles. Knee flexion-extension was tested concentrically at 60°, 180° and 300 °/sec and eccentrically at 60° and 180 °/sec. Ankle dorsal and plantar flexions were tested at 60 °/sec for both the concentric and eccentric mode of action. Bilaterally averaged muscle strength [(R+L)/2] increased significantly from short training age to intermediate and stabilized afterwards. These strength adaptations were mainly observed at the concentric function of knee extensors at 60°/sec (p = 0. 023), knee flexors at 60°/sec (p = 0.042) and 180°/sec (p = 0.036), and ankle plantar flexors at 60o/sec (p = 0.044). A linear trend of increase in isokinetic strength with PTA level was observed for the eccentric strength of knee flexors at 60°/sec (p = 0.02) and 180°/sec (p = 0.03). Directional (R/L) asymmetries decreased with PTA, with this being mainly expressed in the concentric function of knee flexors at 180°/sec (p = 0.04) and at 300 °/sec (p = 0.03). These findings confirm the hypothesis of asymmetry in the strength adaptations that take place at the knee and ankle joint of soccer players mainly along with short and intermediate PTA. Players with a longer PTA seem to adopt a more balanced use of their lower extremities to cope with previously developed musculoskeletal asymmetries and possibly reduce injury risk. This has certain implications regarding proper training and injury prevention in relation to professional experience in soccer. Key pointsMuscle strength increased from the low (5-7 years) to the intermediate professional training age (8-10 years) and stabilized thereafter.Soccer practicing and competition at the professional level induces critical strength adaptations (asymmetries) regarding the function of the knee and ankle musculature.Soccer players with long professional training age showed a tendency for lower isokinetic strength asymmetries than players with intermediate and short professional training age.

This study investigated selected structural correlates of fencing performance. 33 elite fencers were tested on (a) selected anthropometric, flexibility, and strength-power related parameters, and (b) specific lower extremity functional fencing tests. Multiple regression showed that drop jump and thigh cross-sectional area were best predictors of lunge time and distance of squat jump on the shuttle test. When the two performance variables were expressed per Lean Body Mass, lunge time was significantly predicted only by the performance on the arm-driven counter-movement jump, while time on the shuttle test was best predicted by three noncollinear significant predictors: squat jump performance, thigh circumference, and percent body fat. Lunge time and time on the shuttle test were predicted by explosive power, while none of the nontrainable anthropometric measures or years of training seemed to be important in performance of fencing-related skills.

Background: Excessive subtalar pronation causes significant changes in the biomechanics of the lower leg, adversely influences proprioceptive feedback and neuromuscular reflex behavior and consequently, affects stability of the foot. However, the changes in muscle strength, caused by hyperpronation are unclear., Objectives: The purpose of the present study was to compare the evertor and invertor peak torque between hyperpronated and normal individuals as well as between their dominant and non-dominant foot., Method: 20 healthy male participants volunteered for this study. Leg dominance was assessed on the basis of a questionnaire and navicular drop measurements were used to classify participants into two groups: hyperpronated (> or =10 mm) and normals (5-9 mm). Isokinetic concentric eversion and inversion muscle group strength was tested at 30 degrees and 120 degrees/s using the Con-Trex MJ isokinetic dynamometer., Results: In all cases, inversion peak torque was greater than eversion peak torque and declined with increasing angular velocity. No significant differences were found for inversion and eversion concentric strength at both speeds tested, neither between normal and hyperpronated individuals neither between their dominant and non-dominant foot., Conclusions: These results indicate the need re-evaluation of navicular drop values in order to identify normal and abnormal subtalar pronation. The assessment of eccentric contractions is also proposed when examining invertors and evertors isokinetic strength.

Background: Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles., Methods: Thirty three male physical education students who volunteered to take part in the study were measured under three ankle brace conditions: i) without brace, ii) with brace and 30 kPa application pressure and iii) with brace and 60 kPa application pressure. Single limb balance (anteroposterior and mediolateral parameter) was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris) activation onset., Results: The results showed that overall balance (total stability parameter) was not significantly affected in any of the three ankle brace conditions. However, the anteroposterior centre of pressure excursion and centre of pressure excursion velocity were significantly increased with the application of ankle brace, both with 30 and 60 kPa application pressures. Furthermore, it was found that single limb balance was significantly worse with closed eyes compared to open eyes. EMG measurements showed that the sequence of lower limb activation onset was not affected in any of the three ankle brace application conditions. The results of this study showed that the application of an ankle brace with two different skin-brace interface pressures had no effect on overall single limb balance and the sequence of lower limb muscle activation., Conclusion: These findings suggest that peripheral joint receptors are either not adequately stimulated by the brace application and therefore are not able to alter the balance control strategy of the CNS, or that they play a less important role in the control of single limb balance. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended.

Unlabelled: We evaluated whether quadriceps and hamstrings weakness depended on chronicity in amateur athletes with anterior cruciate ligament deficiencies. We hypothesized that the weakness would not recover to the level of healthy control subjects without structured rehabilitation. Secondarily, we asked whether quadriceps and hamstrings side-to-side percent asymmetry in strength was consistent at different stages of chronicity. Thirty-six male amateur athletes forming equal groups of short, intermediate, and long chronicity (mean, 4, 12, and 56 months, respectively) were tested isokinetically against control subjects at 60 degrees per second. Weakness was substantial in both muscle groups and at all times ranging from 32% to 21% compared with the control subjects. However, side-to-side deficits revealed a linear trend of lessening with time. The quadriceps had greater side-to-side asymmetry that ranged from 23% to 10%, whereas the hamstrings asymmetry ranged from 14% to almost 0%. Acquiring symmetric strength earlier than 1 year after injury only occurred in the hamstrings. It can be inferred that participation in organized rehabilitation would minimize the detrimental effects of anterior cruciate ligament rupture on thigh muscle strength., Level of Evidence: Prognostic Study, Level II.

The torque-time curve patterns of concentric isokinetic knee extension in anterior cruciate ligament (ACL) deficient patients usually present mid-range irregularities associated with the level of anterior tibial translation. The purpose of this study was to compare the smoothness in isokinetic torque production between the ACL deficient and the healthy knee. Thirty ACL deficient soccer players performed bilaterally five trials of maximum concentric knee extension-flexion at 60 degrees /s on a Biodex dynamometer. The three middle trials (a total of six curves) were retained and submitted to further data processing. Maximum frequency values contained within the 90%, 95% and 99% level of the signal power were calculated for each extension and flexion curve. The frequency content of the ACL deficient side proved to be statistically higher compared to the intact side at all levels of the power spectrum. The percentage differences in the frequency content were 18.8%, 10.6% and 40.0% for knee extension, and 49.5%, 24.5% and 16.3% for knee flexion, for the respective power levels. This indicated higher oscillations and, therefore, more unstable mechanical output of the injured knee. An overall biological interpretation of the present results is based on the notion that disturbed motion is generally connected to poor level of joint functionality.

Anterior cruciate ligament (ACL) rupture causes instability to the knee joint which leads each patient to a different degree of disability. The purpose of this study was to examine the strength of the quadriceps and the hamstrings in ACL-deficient amateur soccer players at different levels of functional status. Thirty male amateur soccer players were separated into three groups according to their Lysholm score; the high-L1 (Lysholm > or =84), the intermediate-L2 (84> Lysholm > or =72) and the low-L3 (Lysholm <72) knee function groups. The control group consisted of 12 amateur soccer players. The strength of the quadriceps and hamstrings was assessed isokinetically at 60 degrees/s. The quadriceps demonstrated significant deficits of the injured knee compared to the intact knee in all groups, whilst the hamstrings showed significant weakness only in the low function group. Respective percentage deficits in groups L1, L2 and L3 were 13.7%, 16.0% and 18.6% for the quadriceps and 2.4%, 5.6% and 19.2% for the hamstrings. All groups had significant quadriceps weakness which did not differ between the groups. In contrast, the strength deficit of the hamstrings was an indicator of poor knee function, since they were significantly weak only in group L3, which represented patients who clearly failed to compensate for instability symptoms. In groups L1 and L2 the side-to-side differences were within the area of asymmetry measured in the control group. Clinical importance of the results is discussed.

The purpose of this study was two fold a) to determine the levels of hormonal parameters which are related to growth and sexual maturation (T, SHBG, FAI, GH) in 66 pre-pubertal and early-pubertal boys (11-13 years old) who systematically engage in individual and team sports activities of endurance, strength, speed and skill, respectively, and b) to investigate the effect of two different forms of exercise namely aerobic (AG) and weight training (WG) on androgen levels in 19 sedentary pre-pubertal boys. The control groups (CG) consisted of boys of the same age who attended only the school physical education programmes. The individuals included in the study participated voluntarily after their parents had been informed and had given their written consent. Hormonal concentrations were determined using radioimmunoassay and immunoradiometric assays. No differences were observed among the various athletes' groups as regards Tanner stages, height and weight. The mean T and FAI values of the control group did not differ from those of the corresponding athletes group. Significant differences were observed among the groups regarding BMI, % body fat, T, SHBG, FAI and GH (p<0.05). T and FAI values in the WG group were significantly higher than the corresponding concentrations: a) in the AG group by 338 and 609%, p<0.05 and b) in the control group CG by 91 and 96%, p<0.05, respectively. The hormonal differences detected among the various groups of athletes must be attributed as much to the type of physical exercise and to developmental factors as to the selection criteria used for the different athletic talents. The importance of the specificity of training stimulus in the hormonal adaptations of pre-pubertal sedentary subjects was demonstrated.

We investigated hormonal regulators of growth and development, leptin levels, body composition, neuromuscular performance, and the associations among them in trained prepubertal athletes (experimental group [EG]) and an untrained control group (CG). Informed consent was obtained from the children and their parents. Their maturation stage was evaluated according to Tanner's criteria. There were no differences between EG and CG in physical characteristics, body mass index (BMI), lean body mass, testosterone (T), sex hormone-binding globulin, free androgen index, growth hormone (GH), hand grip strength, and jumping performance. Leptin levels and percent fat of the EG were significantly lower than those of the CG (p < 0.05-0.005). Leptin levels were significantly correlated to body fat and BMI for both the EG and the CG (r = 0.51-0.79). There is little evidence that leptin has a positive effect on growth and anabolic factors. Sex hormone-binding globulin and GH may explain the variation of leptin in athletes with low T (R(2) = 0.43) and in CG (R(2) = 0.35), respectively. Leptin seems to be a permissive factor for the onset of puberty, and the training background needs an optimal biological maturation to produce significant differences in muscle and power performance.

The purpose of this study was to examine the effects of four teaching methods on several measures of motor skill, self-concept, and social attitudes of 130 fifth-grade children (67 boys, 63 girls), who were randomly chosen from five elementary schools in one area. Teaching methods were systematically applied for 60 teaching days (20 weeks). Measurements were assessed on three occasions (pre-, mid-, and post-experiment). A 4 x 2 x 3 multivariate analysis of covariance showed the 'combined' method most effective in improving the students' motor ability, while 'indirect' and 'game-oriented' methods contributed to the improvement of self-concept and social attitudes, respectively. Since each of the four methods had different effects on various measures made to evaluate whether aims of physical education had been met, the teacher should be aware of many methods and able to implement them in various combinations, depending upon the special features and purposes of a lesson.