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Training effects on plasma insulin-like growth factor-1 (IGF-1)/cortisol ratio were investigated in boxers. Thirty subjects were assigned to either the training or the control group (n=15 in both). They were tested before the beginning of training (T0), after 5 weeks of intensive training (T1), and after 1 week of tapering (T2). Physical performances (Yo-Yo intermittent recovery test level-1), training loads, and blood sampling were obtained at T0, T1, and T2. Controls were only tested for biochemical and anthropometric parameters at T0 and T2. A significantly higher physical performance was observed at T2 compared to T1. At T1, cortisol levels were significantly increased whereas IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) levels remained unchanged compared to baseline. At T2, cortisol levels decreased while IGF-1 and IGFBP-3 levels increased. The IGF-1/cortisol ratio decreased significantly at T1 and increased at T2, and its variations were significantly correlated with changes in training loads and Yo-Yo intermittent recovery test level 1 (IRT1) performance over the training period. Cortisol variations correlated with changes in training load (r=0.64; p<0.01) and Yo-Yo IRT1 performance (r=0.78; p<0.001) at T1 whereas IGF-1 variations correlated only with changes in Yo-Yo IRT1 performance at T2 (r=0.71; p<0.001). It is concluded that IGF-1/cortisol ratio could be a useful tool for monitoring training loads in young trained boxers. [ABSTRACT FROM AUTHOR]

Training effects on plasma insulin-like growth factor-1 (IGF-1)/cortisol ratio were investigated in boxers. Thirty subjects were assigned to either the training or the control group (n=15 in both). They were tested before the beginning of training (T0), after 5 weeks of intensive training (T1), and after 1 week of tapering (T2). Physical performances (Yo-Yo intermittent recovery test level-1), training loads, and blood sampling were obtained at T0, T1, and T2. Controls were only tested for biochemical and anthropometric parameters at T0 and T2. A significantly higher physical performance was observed at T2 compared to T1. At T1, cortisol levels were significantly increased whereas IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) levels remained unchanged compared to baseline. At T2, cortisol levels decreased while IGF-1 and IGFBP-3 levels increased. The IGF-1/cortisol ratio decreased significantly at T1 and increased at T2, and its variations were significantly correlated with changes in training loads and Yo-Yo intermittent recovery test level 1 (IRT1) performance over the training period. Cortisol variations correlated with changes in training load (r=0.64; p<0.01) and Yo-Yo IRT1 performance (r=0.78; p<0.001) at T1 whereas IGF-1 variations correlated only with changes in Yo-Yo IRT1 performance at T2 (r=0.71; p<0.001). It is concluded that IGF-1/cortisol ratio could be a useful tool for monitoring training loads in young trained boxers. [ABSTRACT FROM AUTHOR]

The present investigation was conducted to evaluate the relative and absolute reliability and the minimal detectable change (MDC95%) of the karate specific aerobic test (KSAT) in male karate athletes. Sixteen subjects (age: 22.2±3.7 years, height: 175.7±6.7 cm, body mass: 72.7±7.2 kg and karate experience: 9.2±4.5 years) participated in this study and performed the KSAT twice (test-retest). Reliability of time to exhaustion (TE) was very good, with intraclass correlation coefficient ICC(3.1)>0.90, standard errors of measurement SEM<5% and 95% limits of agreement (LOA) -15.8 ± 74.7 s. The MDC95% of the KSAT was 81.42 s, rated as “satisfactory”. The dependent t test showed no significant difference between peak heart rate (HRpeak), peak lactate concentration (Lapeak) and rating of perceived exertion (RPE) between test and retest (P>0.05). Effect size for all variables was dz≤0.2, rated as trivial. Thus, when using the present test as a measure of aerobic fitness, a change greater than 9.4% (81.42 s) is necessary to be confident (at the 95% level) that the change in time to exhaustion reflects improvement and exceeds the measurement error. The KSAT is a reliable tool that can be used by practitioners for assessing aerobic fitness in experienced karate athletes. [ABSTRACT FROM AUTHOR]

Background: In karate, the ability to execute high-velocity movements, particularly kicks and punches, is heavily dependent on the strength and power of the lower limb muscles, especially the knee extensors. As such, this study aimed to evaluate the effects of an 8-week eccentric training program utilizing the reverse Nordic exercise (RNE) integrated into karate training compared with regular karate training only on measures of physical fitness in youth karate athletes. Methods: Twenty-seven youth karatekas were recruited and allocated to either RNE group (n = 13; age = 15.35 ± 1.66 years; 7 males and 6 females) or an active control group ([CG]; n = 14; 7 males and 7 females; age = 15.30 ± 1.06 years). To track the changes in measures of physical fitness before and after training, tests to assess linear sprint speed (i.e., 10 m), change of direction (CoD) speed (i.e., modified 505 CoD), vertical jumping (i.e., countermovement jump [CMJ] height) and horizontal jumping distance (i.e., standing long jump [SLJ]), and lower-limb asymmetry score (i.e., the difference between SLJ-dominant and non-dominant legs) were carried out. Results: The results indicated significant group-by-time interactions in all measures of physical fitness (effect size [ES] = 1.03 to 2.89). Post-hoc analyses revealed significant changes in the RNE group across all performance measures (effect size [ES] = 0.33 to 1.63). Additionally, the asymmetry score exhibited a moderate decrease from pre to posttest (∆46.96%, ES = 0.64). In contrast, no significant changes were observed in the CG across all fitness measures. Moreover, the individual response analysis indicated that more karatekas from the RNE group consistently achieved improvements beyond the smallest worthwhile change threshold across all fitness measures. Conclusions: In summary, RNE training is an effective approach to enhance various physical fitness measures besides lower-limb asymmetry scores in youth karatekas and is easy to incorporate into regular karate training. Practitioners are therefore encouraged to consistently integrate RNE training to enhance essential physical fitness components in young karatekas.

Introduction: This study examined the effects of an 8-week backward running (BR) vs. forward running (FR) training programmes on measures of physical fitness in young female handball players., Methods: Twenty-nine players participated in this study. Participants were randomly assigned to a FR training group, BR training group, and a control group., Results and Discussion: Within-group analysis indicated significant, small-to-large improvements in all performance tests (effect size [ g ] = 0.36 to 1.80), except 5-m forward sprint-time in the BR group and 5- and 10-m forward sprint-time in the FR group. However, the CG significantly decreased forward sprint performance over 10-m and 20-m ( g  = 0.28 to 0.50) with no changes in the other fitness parameters. No significant differences in the amount of change scores between the BR and FR groups were noted. Both training interventions have led to similar improvements in measures of muscle power, change of direction (CoD) speed, sprint speed either forward or backward, and repeated sprint ability (RSA) in young female handball players, though BR training may have a small advantage over FR training for 10-m forward sprint time and CoD speed, while FR training may provide small improvements over BR training for RSA best . Practitioners are advised to consider either FR or BR training to improve various measures of physical fitness in young female handball players., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Sammoud, Bouguezzi, Uthoff, Ramirez-Campillo, Moran, Negra, Hachana and Chaabene.)

Background: The 6-min walk test (6MWT) provides information regarding functional capacity, response to therapy and prognosis in a variety of chronic cardiovascular disorders. Variability in body size and composition, particularly in obese people, confounds the six-minute covered distance (6MWD). The aim of the present study was to adopt allometric models to identify the most appropriate body size/shape; i.e., body mass (BM), body height (BH), body mass index (BMI) and estimated fat-free mass (FFM); associated with the 6MWD in 190 young girls with obesity., Methods: Nonlinear allometric modeling was used to calculate common body size exponents for BM, BH, BMI and FFM. In a validation sample of 35 age-matched obese girls, these allometric exponents were used prospectively., Results: The point estimates for the size exponents (95% confidence interval) from the separate allometric models were: BM 0.23 (0.19-0.27), BH 0.91 (0.78-1.03), BMI 0.33 (0.23-0.44) and FFM 0.28 (0.24-0.33). The presence of significant residual size correlations for 6MWD/BH -0.91 indicates that the influence of body size was not correctly partitioned out. In the validation group, the correlations between 6MWD BM -b and BM, 6MWD BMI -b and BMI, and 6MWD FFM -b and FFM using the established exponents were not statistically different from zero (r = 0.01), implying that participants in the allometric investigation were not penalized based on their BM, BMI, or FFM., Conclusion: We conclude that BM, BMI, BH and FFM, as indicators of body size/shape, are the most valid allometric denominators for the scaling of 6MWD in a group of young girls with obesity.

The objective of this study is to characterize purebred Arab mares' milk through monitoring its physicochemical and microbiological composition during different lactation stages and to test its ability to coagulate. Sixteen purebred Arabian mares were selected among 45 mares with approximately the same foaling dates. Milk samples were collected once a week for each mare during 4 months of lactation and analysed in three replicates for physicochemical composition, nitrogen fractions, somatic cell count and total bacterial count. Coagulation assays were carried out in triplicates on fresh mare's milk using increasing doses of calf rennet, starter ( Streptococcus thermophilus ) and CaCl 2 . Arab mare's milk is characterized by an alkaline pH, low-fat and protein contents and high lactose content. The somatic cell and bacterial counts are very low, indicating good health status of mares. Fat and protein contents decreased as the stage of lactation progressed. However, as lactation number increased, fat level tended to increase while protein level tended to decrease. Clotting assays proved that it is possible to coagulate Arabian mare's milk using appropriate doses of calf rennet and starter, while respecting the coagulation procedures and parameters., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interests., (© Association of Food Scientists & Technologists (India) 2021.)

The apparent dry matter digestibility of diets for rabbits was measured in vivo (ADMD vv ) and in vitro with the Ankom Daisy II Incubator. Four diets were tested: low fiber (LF), LF + 5% of pregerminated fenugreek seeds (PGFS) (LF5), LF + 10% PGFS (LF10), and high fiber (HF). For the ADMD vv , feces samples were collected from 56 White New-Zealand × Californian rabbits fed the 4 diets; animals were randomly allocated into 4 groups and housed in individual cages. For the in vitro trial, 3 methods were tested: fecal inoculum (FA) with Kansans State buffer; fecal inoculum with artificial saliva (FB); and multienzyme (ENZ). Fecal inocula were collected at slaughtering from the distal colon of rabbits fed ad libitum the LF diet. For FA and FB methods, the digestibility was measured at 36 and 48 h. The in vitro methods ranked the apparent dry matter digestibility of diets in the same order as in vivo, but ENZ values were always higher than FA and FB at 36 and 48 h. The prediction equations of in vivo digestibility with the ENZ method showed higher coefficient of determination (R 2 = 0.69) and lower SE (0.190) than FA and FB; also, reproducibility was higher with ENZ (CV = 3.1%). In conclusion, different methods can be applied to the Ankom Daisy II Incubator to study the digestibility in rabbits. In our trial, the better reproducibility was observed with the multienzyme method than FA and FB were probably related to the variability of inocula.

This study aimed to examine the reliability and the time-of-day effect of the 505 change of direction (CoD), 10-m sprint, and change of direction deficit test (CoDD). At two different time of days, 39 young diurnally active physical education male students performed different physical tests: 505 CoD, and sprint tests. Measurements were taken at two separate testing sessions, i.e. in the morning (07:00-08:30 h) and early evening (17:00-18:30 h) in a randomized and counter-balanced setting on nonconsecutive days in 21 of them (21.5 ± 1.5 y of age). The results showed that the 505 CoD test, 10-m sprint, and CoDD performances were a reliable test, and performances were better in the evening the 505 CoD, 10-m sprint, and CoDD testing provided reliable and sensitive scores. In addition, phase 2 showed that CoD, speed, and CoDD are affected by the time of day.

Background/objective: Dry land-training (e.g., plyometric jump training) can be a useful mean to improve swimming performance. This study examined the effects of an 8-week plyometric jump training (PJT) program on jump and sport-specific performances in prepubertal female swimmers., Methods: Twenty-two girls were randomly assigned to either a plyometric jump training group (PJT G ; n = 12, age: 10.01 ± 0.57 years, maturity-offset = -1.50 ± 0.50, body mass = 36.39 ± 6.32 kg, body height = 146.90 ± 7.62 cm, body mass index = 16.50 ± 1.73 kg/m2) or an active control (CG; n = 10, age: 10.50 ± 0.28 years, maturity-offset = -1.34 ± 0.51, body mass = 38.41 ± 9.42 kg, body height = 143.60 ± 5.05 cm, body mass index = 18.48 ± 3.77 kg/m2). Pre- and post-training, tests were conducted for the assessment of muscle power (e.g., countermovement-jump [CMJ], standing-long-jump [SLJ]). Sport-specific-performances were tested using the timed 25 and 50-m front crawl with a diving-start, timed 25-m front crawl without push-off from the wall (25-m WP), and a timed 25-m kick without push-off from the wall (25-m KWP)., Results: Findings showed a significant main effect of time for the CMJ (d = 0.78), the SLJ (d = 0.91), 25-m front crawl test (d = 2.5), and the 25-m-KWP (d = 1.38) test. Significant group × time interactions were found for CMJ, SLJ, 25-m front crawl, 50-m front crawl, 25-m KWP, and 25-m WP test (d = 0.29-1.63) in favor of PJT G (d = 1.34-3.50). No significant pre-post changes were found for CG (p > 0.05)., Conclusion: In sum, PJT is effective in improving muscle power and sport-specific performances in prepubertal swimmers. Therefore, PJT should be included from an early start into the regular training program of swimmers., Competing Interests: The authors declare no conflict of interest., (© 2020 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd.)

Purpose: This study aimed to assess the effectiveness and time course for improvements in explosive actions through resistance training (RT) vs. plyometric training (PT) in prepubertal soccer players., Methods: Thirty-four male subjects were assigned to: a control group (n = 11); an RT group (5 regular soccer training sessions per week, n = 12); a PT group (3 soccer training sessions and 2 RT sessions per week, n = 11). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum half-squat test), jump ability (e.g., countermovement jump, squat jump, standing long jump, and multiple 5 bounds test), linear speed (e.g., 20 m sprint test), and change of direction (e.g., Illinois change of direction test)., Results: The RTG showed an improvement in the half-squat (Δ = 13.2%; d = 1.3, p< 0.001) and countermovement jump (Δ = 9.4%; d = 2.4, p< 0.001) at Week 4, whereas improvements in the 20-m sprint (Δ = 4.2%; d = 1.1, p < 0.01); change of direction (CoD) (Δ = 3.8%; d = 2.1, p < 0.01); multiple 5 bounds (Δ = 5.1%; d = 1.5, p < 0.05); standing long jump (Δ = 7.2%; d = 1.2, p < 0.01); squat jump (Δ = 19.6%; d = 1.5, p < 0.01); were evident at Week 8. The PTG showed improvements in CoD (Δ = 2.1%; d = 1.3, p< 0.05); standing long jump (Δ = 9.3%; d = 1.1, p< 0.01); countermovement jump (Δ = 16.1%; d = 1.2, p< 0.01); and squat jump (Δ = 16.7%; d = 1.4, p< 0.01); at Week 8 whereas improvements in the 20-m sprint (Δ = 4.1%; d = 1.3, p < 0.01); and multiple 5 bounds (Δ = 7.4%; d = 2.4, p< 0.001); were evident only after Week. The RT and PT groups showed improvements in all sprint, CoD, and jump tests (p< 0.05) and in half-squat performance, for which improvement was only shown within the RTG (p< 0.001)., Conclusion: RT and PT conducted in combination with regular soccer training are safe and feasible interventions for prepubertal soccer players. In addition, these interventions were shown to be effective training tools to improve explosive actions with different time courses of improvements, which manifested earlier in the RTG than in the PTG. These outcomes may help coaches and fitness trainers set out clear and concise goals of training according to the specific time course of improvement difference between RT and PT on proxies of athletic performance of prepubertal soccer players., (Copyright © 2016. Production and hosting by Elsevier B.V.)

Bouguezzi, R, Chaabene, H, Negra, Y, Ramirez-Campillo, R, Jlalia, Z, Mkaouer, B, and Hachana, Y. Effects of different plyometric training frequencies on measures of athletic performance in prepuberal male soccer players. J Strength Cond Res 34(6): 1609-1617, 2020-This study aimed to compare the effects of 1 vs. 2 sessions of equal-weekly volume plyometric training (PT) across 8 weeks on measures of athletic performance (i.e., sprint time, change of direction [CoD], jumping ability, and muscle strength) in prepuberal male soccer players. Thirty participants were randomly assigned either to 1 session PT group (1SPT [n = 15]) or 2 sessions PT group (2SPT [n = 15]). Plyometric training was integrated into their regular soccer training routine. Pretraining and posttraining tests for the assessment of sprint time (e.g., 5, 10, 20, and 30-m), CoD (e.g., T-test and modified Illinois change of direction test [MICODT]), jumping ability (e.g., standing long jump [SLJ], countermovement jump [CMJ], and squat jump [SJ]), muscle strength (reactive strength index [RSI]), and kicking distance were conducted. Results showed a main effect of time for 5-m sprint-time performance (F(1,56) = 4.00, effect size [ES] = 0.53 [medium], p = 0.05), T-test (F(1,56) = 23.19, ES = 1.28 [large], p < 0.001), MICODT (F(1,56) = 5.72, ES = 0.94 [large], p = 0.02), SLJ (F(1,56) = 16.63, ES = 1.09 [large], p < 0.001), CMJ (F(1,56) = 15.43, ES = 1.04 [large], p < 0.001), SJ (F(1,56) = 20.27, ES = 1.20 [large], p < 0.001), RSI (F(1,56) = 26.26, ES = 1.36 [large], p < 0.001), and kicking distance (F(1,56) = 47.19, ES = 1.83 [large], p < 0.001). There were no training group × time interactions in all the measured outcomes. In conclusion, when an equated moderate volume of jumps is performed, higher PT frequency across 8 weeks has no extra effects on prepuberal male soccer players' measures of athletic performance. The present findings may help optimizing PT interventions dedicated to prepuberal male soccer players.

The purpose of this study was to estimate the optimal body size, limb-segment length, girth or breadth ratios for 100-m backstroke mean speed performance in young swimmers. Sixty-three young swimmers (boys [n = 30; age: 13.98 ± 0.58 years]; girls [n = 33; age: 13.02 ± 1.20 years]) participated in this study. To identify the optimal body size and body composition components associated with 100-m backstroke speed performance, we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 100-m backstroke mean speed performance and the different somatic measurements estimated that biological age, sitting height, leg length for the lower-limbs, and two girths (forearm and arm relaxed girth) are the key predictors. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. In fact, it is only by adopting multiplicative allometric models that the abovementioned ratios could have been derived. These findings highlighted the importance of considering somatic characteristics of young backstroke swimmers and can help swimming coaches to classify their swimmers and enable them to suggest what might be the swimmers' most appropriate stroke (talent identification).

Chaabene, H, Negra, Y, Capranica, L, Bouguezzi, R, Hachana, Y, Rouahi, MA, and Mkaouer, B. Validity and reliability of a new test of planned agility in elite taekwondo athletes. J Strength Cond Res 32(9): 2542-2547, 2018-This study aimed to examine the validity, reliability, and sensitivity of a new test of planned agility in elite taekwondo athletes and to establish its relationship with sprint-time, jumping ability, and dynamic balance. Twenty-seven (20 males and 7 females) taekwondo athletes participated in this study. They performed taekwondo-specific agility test (TSAT) in 2 occasions (i.e., test-retest). In addition, they performed jumping ability (i.e., squat jump, countermovement jump, standing long jump, and 3-hop jump), sprint-time (5- and 20-m dash), and dynamic balance (i.e., Y-test) tests along with a planned agility test (i.e., T-test). To establish TSAT's construct validity, 2 subgroups were identified based on their international and national taekwondo results: top elite (9 males and 2 females) and elite (11 males and 2 females). Taekwondo-specific agility test showed high relative and absolute reliability as well as a good ability to detect small and meaningful performance change. Top-elite athletes showed greater (p < 0.001) TSAT performances (4.5 ± 0.4 seconds) compared with their elite (5.3 ± 0.4 seconds) counterparts. Receiving operating characteristic (ROC) analysis showed that TSAT was able to discriminate athletes of different competitive level as revealed by an area under the ROC curve of 0.94 (95% confidence interval: 0.76-0.99). Taekwondo-specific agility test demonstrated significant association with the T-test (r = 0.71; shared variance = 50%), which is considered as a gold-standard planned agility test. In addition, results showed moderate-to-large associations between TSAT and jumping ability, sprint-time, and dynamic balance tests. The TSAT might be considered as a valid and reliable test to evaluate specific agility of taekwondo athletes.

This study aimed to estimate the optimal body size, limb segment length, and girth or breadth ratios of 100-m breaststroke performance in youth swimmers. In total, 59 swimmers [male: n = 39, age = 11.5 (1.3) y; female: n = 20, age = 12.0 (1.0) y] participated in this study. To identify size/shape characteristics associated with 100-m breaststroke swimming performance, we computed a multiplicative allometric log-linear regression model, which was refined using backward elimination. Results showed that the 100-m breaststroke performance revealed a significant negative association with fat mass and a significant positive association with the segment length ratio (arm ratio = hand length/forearm length) and limb girth ratio (girth ratio = forearm girth/wrist girth). In addition, leg length, biacromial breadth, and biiliocristal breadth revealed significant positive associations with the 100-m breaststroke performance. However, height and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. In fact, it is only by adopting multiplicative allometric models that the previously mentioned ratios could have been derived. These results highlighted the importance of considering anthropometric characteristics of youth breaststroke swimmers for talent identification and/or athlete monitoring purposes. In addition, these findings may assist orienting swimmers to the appropriate stroke based on their anthropometric characteristics.

Background: This study aimed to estimate the optimal body size, limb-segment length, and girth or breadth ratios associated with 100-m butterfly speed performance in swimmers., Methods: One-hundred-sixty-seven swimmers as subjects (male: N.=103; female: N.=64). Anthropometric measurements comprised height, body-mass, skinfolds, arm-span, upper-limb-length, upper-arm, forearm, hand-lengths, lower-limb-length, thigh-length, leg-length, foot-length, arm-relaxed-girth, forearm-girth, wrist-girth, thigh-girth, calf-girth, ankle-girth, biacromial and biiliocristal-breadths. To estimate the optimal body size and body composition components associated with 100-m butterfly speed performance, we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination., Results: Fat-mass was the singularly most important whole-body characteristic. Height and body-mass did not contribute to the model. The allometric model identified that having greater limb segment length-ratio (arm-ratio = [arm-span]/[forearm]) and limb girth-ratio (girth-ratio = [calf-girth]/[ankle-girth]) were key to butterfly speed performance. A greater arm-span to forearm-length ratio and a greater calf to ankle-girth-ratio suggest that a combination of larger arm-span and shorter forearm-length and the combination of larger calves and smaller ankles-girth may benefit butterfly swim speed performance. In addition having greater biacromial and biliocristal breadths is also a major advantage in butterfly swimming speed performance. Finally, the estimation of these ratios was made possible by adopting a multiplicative allometric model that was able to confirm, theoretically, that swim speeds are nearly independent of total body size., Conclusions: The 100-m butterfly speed performance was strongly negatively associated with fat mass and positively associated with the segment length ratio (arm-span/forearm-length) and girth ratio (calf-girth)/(ankle-girth), having controlled for the developmental changes in age.

Negra, Y, Chaabene, H, Sammoud, S, Bouguezzi, R, Mkaouer, B, Hachana, Y, and Granacher, U. Effects of plyometric training on components of physical fitness in prepuberal male soccer athletes: the role of surface instability. J Strength Cond Res 31(12): 3295-3304, 2017-Previous studies contrasted the effects of plyometric training (PT) conducted on stable vs. unstable surfaces on components of physical fitness in child and adolescent soccer players. Depending on the training modality (stable vs. unstable), specific performance improvements were found for jump (stable PT) and balance performances (unstable PT). In an attempt to combine the effects of both training modalities, this study examined the effects of PT on stable surfaces compared with combined PT on stable and unstable surfaces on components of physical fitness in prepuberal male soccer athletes. Thirty-three boys were randomly assigned to either a PT on stable surfaces (PTS; n = 17; age = 12.1 ± 0.5 years; height = 151.6 ± 5.7 cm; body mass = 39.2 ± 6.5 kg; and maturity offset = -2.3 ± 0.5 years) or a combined PT on stable and unstable surfaces (PTC; n = 16; age = 12.2 ± 0.6 years; height = 154.6 ± 8.1 cm; body mass = 38.7 ± 5.0 kg; and maturity offset = -2.2 ± 0.6 years). Both intervention groups conducted 4 soccer-specific training sessions per week combined with either 2 PTS or PTC sessions. Before and after 8 weeks of training, proxies of muscle power (e.g., countermovement jump [CMJ], standing long jump [SLJ]), muscle strength (e.g., reactive strength index [RSI]), speed (e.g., 20-m sprint test), agility (e.g., modified Illinois change of direction test [MICODT]), static balance (e.g., stable stork balance test [SSBT]), and dynamic balance (unstable stork balance test [USBT]) were tested. An analysis of covariance model was used to test between-group differences (PTS vs. PTC) at posttest using baseline outcomes as covariates. No significant between-group differences at posttest were observed for CMJ (p > 0.05, d = 0.41), SLJ (p > 0.05, d = 0.36), RSI (p > 0.05, d = 0.57), 20-m sprint test (p > 0.05, d = 0.06), MICODT (p > 0.05, d = 0.23), and SSBT (p > 0.05, d = 0.20). However, statistically significant between-group differences at posttest were noted for the USBT (p < 0.01, d = 1.49) in favor of the PTC group. For most physical fitness tests (except RSI), significant pre-to-post improvements were observed for both groups (p < 0.01, d = 0.55-3.96). Eight weeks of PTS or PTC resulted in similar performance improvements in components of physical fitness except for dynamic balance. From a performance-enhancing perspective, PTC is recommended for pediatric strength and conditioning coaches because it produced comparable training effects as PTS on proxies of muscle power, muscle strength, speed, agility, static balance, and additional effects on dynamic balance.

Change of direction ability is an essential pre-requisite in team sports athletes. The Illinois change of direction test has been routinely used for testing change of direction ability in soccer players. The aim of the present study was to evaluate the Illinois change of direction test in young elite soccer players in terms of its reliability, usefulness and relationship with body size. A total of one hundred and ninety-four male, national-level soccer players were recruited. They were classified into four age groups (U-8, U-10, U-12 and U-14). Participants were tested using the Illinois change of direction test twice, and basic indices of body size were obtained. The Illinois change of direction scores showed high relative and absolute reliability in all age groups (all intraclass correlation coefficients were >0.91, and the standard error of measurement was <5%). The usefulness analysis showed that the Illinois change of direction test could detect small changes in performance in the U-10 and U-12 groups. However, it could only detect moderate changes in performance in the U-8 and U-14 groups. Although the Illinois change of direction test detected significant performance differences among groups, scores were not significantly related to body size (-0.30 0.05). Taking into account the test's high reliability and the appropriate level of usefulness, these results might support the use of the Illinois change of direction test as a standard measure for quantifying change of direction ability in young soccer players.

This study aimed at examining the effects of plyometric training on stable (SPT) vs. unstable (UPT) surfaces on physical fitness in prepuberal soccer players. Male athletes were randomly assigned to SPT (n=18; age=12.7±0.2 years) or UPT (n=16; age=12.2±0.5 years). Both groups conducted 3 regular soccer training sessions per week combined with either 2 SPT or UPT sessions. Assessment of jumping ability (countermovement jump [CMJ], and standing long jump [SLJ]), speed (10-m, 20-m, 30-m sprint), agility (Illinois agility test [IAT]), and balance (stable [SSBT], unstable [USBT] stork balance test; stable [SYBT], unstable [UYBT] Y balance test) was conducted pre-and post-training. An ANCOVA model was used to test for between-group differences (SPT vs. UPT) at post-test using baseline values as covariates. No significant differences were found for CMJ height (p>0.05, d=0.54), SLJ (p>0.05; d=0.81), 10-m, 20-m, and 30-m sprint performances (p>0.05, d=0.00-0.24), IAT (p>0.05, d=0.48), and dynamic balance (SYBT and UYBT, both p>0.05, d=0.39, 0.08, respectively). Statistically significant between-group differences were detected for the USBT (p<0.01, d=1.86) and the SSBT (p<0.01, d=1.75) in favor of UPT. Following 8 weeks of SPT or UPT in prepuberal athletes, similar performance levels were observed in both groups for measures of jumping ability, speed, dynamic balance, and agility. However, if the goal is to additionally enhance static balance, UPT has an advantage over SPT., (© Georg Thieme Verlag KG Stuttgart · New York.)

Chaabene, H, Negra, Y, Bouguezzi, R, Mkaouer, B, Franchini, E, Julio, U, and Hachana, Y. Physical and physiological profile of wrestler athletes: a short review. J Strength Cond Res 31(5): 1411-1442, 2017-Wrestling is one of the oldest combat sports, disputed since the ancient Greek Olympic Games. This combat sport discipline has caught the attention of scientists since 1943 which is the date that matches the appearance of the first scientific research dealing with wrestling. The current short review aimed to summarize and critically analyze the scientific literature related to wrestling's physical and physiological attributes and to provide practical recommendations for testing/training together with new perspective and areas of future scientific research. Regardless of sex and wrestling styles, an optimal level of cardiorespiratory fitness is important to help sustaining effort throughout the duration of the match and to stimulate the recovery process between periods. With regard to the anaerobic power and capacity, the available studies were in agreement about their critical importance toward reaching high-level wrestling success since these variables have discriminated well between successful and less-successful wrestlers regardless of age, weight classes, and wrestling styles. Physical fitness parameters such as maximal dynamic strength, isometric strength, explosive strength, and strength endurance are closely related to high-level wrestling performance. However, flexibility level seems not to be one of the key fitness variables that help to reach high-level wrestling success. Overall, to achieve high-level wrestling performance, training should be directed to develop anaerobic power and capacity, aerobic power, maximal dynamic and isometric strength, explosive strength, and strength endurance.

Negra, Y, Chaabene, H, Hammami, M, Amara, S, Sammoud, S, Mkaouer, B, and Hachana, Y. Agility in young athletes: is it a different ability from speed and power? J Strength Cond Res 31(3): 727-735, 2017-Agility is an important physical attribute for successful participation in team sports events. Illinois agility test (IAT) and T-test have been widely used within adult team sports players to assess agility performance. The purposes of this investigation are (a) to study the reliability and the sensitivity of both IAT and T-test scores and (b) to explore to what extend the agility is an independent physical ability from speed time and jumping ability. Competitive-level young soccer (n = 95) and handball players (n = 92) participated in this study (i.e., approximately 12 years old). Reliability analyses were established by determining intraclass correlation coefficient (ICC(3,1)) and typical error of measurement (TEM). The sensitivity of agility tests was revealed by comparing TEM to the value of the smallest worthwhile change (SWC). The second aim was examined by means of the principal component analysis. Results revealed that the scores of both IAT and T-test showed a high reliability (all ICC(3,1) > 0.90 and TEM < 5%) and sensitivity (all TEM < SWC). Principal component analysis resulted in one significant component for the soccer and handball group each that explained 72.18 and 80.16% of the total variance, respectively. Significant relationships were recorded between all the selected tests (r = -0.72 to 0.85, p < 0.001). Based on the results of this study, it was concluded that both IAT and T-test provided reliable and sensitive scores. Therefore, these tests could be strongly recommended to evaluate agility within young male competitive-level team sports athletes. In addition, it seems that agility, speed time, and jumping ability assess the same physical attribute in young competitive-level team sports players.

Negra, Y, Chaabene, H, Hammami, M, Hachana, Y, and Granacher, U. Effects of high-velocity resistance training on athletic performance in prepuberal male soccer athletes. J Strength Cond Res 30(12): 3290-3297, 2016-The aim of this study was to assess the effectiveness of a 12-week in-season low-to-moderate load high-velocity resistance training (HVRT) in addition to soccer training as compared with soccer training only on proxies of athletic performance in prepubertal soccer players. Twenty-four male soccer players performed 2 different protocols: (a) regular soccer training with 5 sessions per week (n = 11; age = 12.7 ± 0.3 years) and (b) regular soccer training with 3 sessions per week and HVRT with 2 sessions per week (n = 13; age = 12.8 ± 0.2 years). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum [1RM] half-squat tests), jump ability (e.g., countermovement jump, squat jump [SJ], standing long jump [SLJ], and multiple 5-bound tests [MB5s]), linear speed (e.g., 5-, 10-, 20-, and 30-m sprint tests), and change of direction (e.g., T-test and Illinois change of direction test). Results revealed significant group × test interactions for the SJ test (p ≤ 0.05, d = 0.59) and the SLJ test (p < 0.01, d = 0.83). Post hoc tests illustrated significant pre-post changes in the HVRT group (SJ: [INCREMENT]22%, p < 0.001, d = 1.26; SLJ: [INCREMENT]15%, p < 0.001, d = 1.30) but not in the control group. In addition, tendencies toward significant interaction effects were found for the 1RM half-squat (p = 0.08, d = 0.54) and the 10-m sprint test (p = 0.06, d = 0.57). Significant pre-post changes were found for both parameters in the HVRT group only (1RM: [INCREMENT]25%, p < 0.001, d = 1.23; 10-m sprint: [INCREMENT]7%, p < 0.0001, d = 1.47). In summary, in-season low-to-moderate load HVRT conducted in combination with regular soccer training is a safe and feasible intervention that has positive effects on maximal strength, vertical and horizontal jump and sprint performance as compared with soccer training only.

Background: This study aimed to evaluate the relationship between physiological, and parameters of performance analysis during karate contest., Methods: Nine elite-level karate athletes participated in this study. Saliva sample was collected pre- and post-karate combat., Results: Salivary cortisol (sC) post-combat 2 raised significantly compared to that recorded at pre-combat 1 (Δ%=105.3%; P=0.04; dz=0.78). The largest decrease of the salivary T/C ratio (sR) compared to pre-combat 1 was recorded post-combat 2 (Δ%=-43.5%; P=0.03). Moreover, blood lactate concentration post-combat 1 correlated positively to sCpost-combat 1 (r=0.66; P=0.05) and negatively to both salivary testosterone (sT) (r=-0.76; P=0.01) and sRpost-combat 1 (r=-0.76; P=0.01). There was no significant relationship between hormonal measures and parameters of match analysis., Conclusions: Although under simulated condition, karate combat poses large physiological stress to the karateka. Additionally, physiological strain to karate combat led to a catabolic hormonal response.

Background: Karate is one the most popular combat sports in the world. Physical fitness assessment on a regular manner is important for monitoring the effectiveness of the training program and the readiness of karatekas to compete., Objectives: The aim of this research was to examine the criterion related to validity of the karate specific aerobic test (KSAT) as an indicator of aerobic level of karate practitioners., Patients and Methods: Cardiorespiratory responses, aerobic performance level through both treadmill laboratory test and YoYo intermittent recovery test level 1 (YoYoIRTL1) as well as time to exhaustion in the KSAT test (TE'KSAT) were determined in a total of fifteen healthy international karatekas (i.e. karate practitioners) (means ± SD: age: 22.2 ± 4.3 years; height: 176.4 ± 7.5 cm; body mass: 70.3 ± 9.7 kg and body fat: 13.2 ± 6%)., Results: Peak heart rate obtained from KSAT represented ~99% of maximal heart rate registered during the treadmill test showing that KSAT imposes high physiological demands. There was no significant correlation between KSAT's TE and relative (mL/min kg) treadmill maximal oxygen uptake (r = 0.14; P = 0.69; [small]). On the other hand, there was a significant relationship between KSAT's TE and the velocity associated with VO2max (vVO2max) (r = 0.67; P = 0.03; [large]) as well as the velocity at VO2 corresponding to the second ventilatory threshold (vVO2 VAT) (r = 0.64; P = 0.04; [large]). Moreover, significant relationship was found between TE's KSAT and both the total distance covered and parameters of intermittent endurance measured through YoYoIRTL1., Conclusions: The KSAT has not proved to have indirect criterion related validity as no significant correlations have been found between TE's KSAT and treadmill VO2max. Nevertheless, as correlated to other aerobic fitness variables, KSAT can be considered as an indicator of karate specific endurance. The establishment of the criterion related validity of the KSAT requires further investigation.

Boxing is one of the oldest combat sports. The aim of the current review is to critically analyze the amateur boxer's physical and physiological characteristics and to provide practical recommendations for training as well as new areas of scientific research. High-level male and female boxers show a propensity for low body fat levels. Although studies on boxer somatotypes are limited, the available information shows that elite-level male boxers are characterized by a higher proportion of mesomorphy with a well-developed muscle mass and a low body fat level. To help support the overall metabolic demands of a boxing match and to accelerate the recovery process between rounds, athletes of both sexes require a high level of cardiorespiratory fitness. International boxers show a high peak and mean anaerobic power output. Muscle strength in both the upper and lower limbs is paramount for a fighter's victory and is one of the keys to success in boxing. As boxing punches are brief actions and very dynamic, high-level boxing performance requires well-developed muscle power in both the upper and lower limbs. Albeit limited, the available studies reveal that isometric strength is linked to high-level boxing performance. Future investigations into the physical and physiological attributes of boxers are required to enrich the current data set and to help create a suitable training program.

The intent of this study was to evaluate relative and absolute reliability of the 20-s anaerobic test (WAnT20) versus the WAnT30 and to verify how far the various indices of the 30-s Wingate anaerobic test (WAnT30) could be predicted from the WAnT20 data in male athletes. The participants were Exercise Science majors (age: 21.5±1.6 yrs, stature: 0.183±0.08 m, body mass: 81.2±10.9 kg) who participated regularly in team sports. In Phase I, 41 participants performed duplicate WAnT20 and WAnT30 tests to assess reliability. In Phase II, 31 participants performed one trial each of the WAnT20 and WAnT30 to determine the ability of the WAnT20 to predict components of the WAnT30. In Phase III, 31 participants were used to cross-validate the prediction equations developed in Phase II. Respective intra-class correlation coefficients (ICC) for peak power output (PPO) (ICC = 0.98 and 0.95) and mean power output (MPO) (ICC 0.98 and 0.90) did not differ significantly between WAnT20 and WAnT30. ICCs for minimal power output (POmin) and fatigue index (FI) were poor for both tests (range 0.53 to 0.76). Standard errors of the means (SEM) for PPO and MPO were less than their smallest worthwhile changes (SWC) in both tests; however, POmin and FI values were "marginal," with SEM values greater than their respective SWCs for both tests values. Stepwise regression analysis showed that MPO had the highest coefficient of predictability (R = 0.97), with POmin and FI considerable lower (R = 0.71 and 0.41 respectively). Cross-validation showed insignificant bias with limits of agreement of 0.99±1.04, 6.5±92.7 W, and 1.6±9.8% between measured and predicted MPO, POmin, and FI, respectively. WAnT20 offers a reliable and valid test of leg anaerobic power in male athletes and could replace the classic WAnT30.

Background: Agility is a determinant component in soccer performance. This study aimed to evaluate the reliability and sensitivity of a "Modified Illinois change of direction test" (MICODT) in ninety-five U-14 soccer players., Methods: A total of 95 U-14 soccer players (mean ± SD: age: 13.61 ± 1.04 years; body mass: 30.52 ± 4.54 kg; height: 1.57 ± 0.1 m) from a professional and semi-professional soccer academy, participated to this study. Sixty of them took part in reliability analysis and thirty-two in sensitivity analysis., Results: The intraclass correlation coefficient (ICC) that aims to assess relative reliability of the MICODT was of 0.99, and its standard error of measurement (SEM) for absolute reliability was <5% (1.24%). The MICODT's capacity to detect change is "good", it's SEM (0.10 s) was ≤ SWC (0.33 s). The MICODT is significantly correlated to the Illinois change of direction speed test (ICODT) (r = 0.77; p<0.0001). The ICODT's MDC95 (0.64 s) was twice about the MICODT's MDC95 (0.28 s), indicating that MICODT presents better ability to detect true changes than ICODT. The MICODT provided good sensitivity since elite U-14 soccer players were better than non-elite one on MICODT (p = 0.005; dz = 1.01 [large]). This was supported by an area under the ROC curve of 0.77 (CI 95%, 0.59 to 0.89, p<0.0008). The difference observed in these two groups in ICODT was not statistically significant (p = 0.14; dz = 0.51 [small]), showing poor discriminant ability., Conclusion: MICODT can be considered as more suitable protocol for assessing agility performance level than ICODT in U-14 soccer players.

The purposes of this study were first to assess the reliability and criterion-related validity of the Illinois change of direction (COD) Illinois Agility Test (IAGT) and second to determine whether a relationship with power and speed exists. A total of 105 male team sport athletes participated in this investigation. Repeat measurements in 89 subjects out of the 105 were performed to assess the test-retest reliability and the 95% confidence interval (CI) of the difference in the score between paired observations (minimal detectable change [MDC]95) of the COD IAGT. The intraclass correlation coefficient and the SEM values for the COD IAGT test were 0.96 (95% CI, 0.85-0.98) and 0.19 seconds, respectively. The smallest worthwhile change (0.20 seconds) for the IAGT was greater than its SEM (0.19 seconds). The MDC95 value for the IAGT was 0.52 seconds. Criterion-related validity of the COD IAGT was assessed in the 105 subjects. They performed the COD IAGT and the T-test. Both tests were significantly correlated (r = 0.31 [95% CI, 0.24-0.39]; p < 0.05). The correlation between COD IAGT, acceleration, straight speed, and leg power was analyzed in all the 105 subjects. Pearson moment correlation revealed no association between acceleration and the COD IAGT. However, significant correlations were observed between the COD IAGT and leg power (r = -0.39 [95% CI, -0.26 to -0.44]; p < 0.05), and speed (r = 0.42 [95% CI, 0.37-0.51]; p < 0.05). When controlling for speed with partial correlation, the significant relationship between the COD IAGT and leg power disappeared. In conclusion, the COD IAGT seems to be a reliable and valid test, whose performance is significantly related to speed rather than to acceleration and leg power.

ABThe aim of this study was to examine absolute and relative reliabilities and external responsiveness of the Karate-specific aerobic test (KSAT). This study comprised 43 male karatekas, 19 of them participated in the first study to establish test-retest reliability and 40, selected on the bases of their karate experience and level of practice, participated in the second study to identify external responsiveness of the KSAT. The latter group was divided into 2 categories: national-level group (G(n)) and regional-level group (G(r)). Analysis showed excellent test-retest reliability of time to exhaustion (TE), with intraclass correlation coefficient ICC(3,1) >0.90, standard error of measurement (SEM) <5%: (3.2%) and mean difference (bias) ± the 95% limits of agreement: -9.5 ± 78.8 seconds. There was a significant difference between test-retest session in peak lactate concentration (Peak [La]) (9.12 ± 2.59 vs. 8.05 ± 2.67 mmol·L(-1); p < 0.05) but not in peak heart rate (HRpeak) and rating of perceived exertion (RPE) (196 ± 9 vs. 194 ± 9 b·min(-1) and 7.6 ± 0.93 vs. 7.8 ± 1.15; p > 0.05), respectively. National-level karate athletes (1,032 ± 101 seconds) were better than regional level (841 ± 134 seconds) on TE performance during KSAT (p < 0.001). Thus, KSAT provided good external responsiveness. The area under the receiver operator characteristics curve was >0.70 (0.86; confidence interval 95%: 0.72-0.95). Significant difference was detected in Peak [La] between national- (6.09 ± 1.78 mmol·L(-1)) and regional-level (8.48 ± 2.63 mmol·L(-1)) groups, but not in HRpeak (194 ± 8 vs. 195 ± 8 b·min(-1)) and RPE (7.57 ± 1.15 vs. 7.42 ± 1.1), respectively. The result of this study indicates that KSAT provides excellent absolute and relative reliabilities. The KSAT can effectively distinguish karate athletes of different competitive levels. Thus, the KSAT may be suitable for field assessment of aerobic fitness of karate practitioners.

This review focuses on the most important physical and physiological characteristics of karate athletes from the available scientific research. It has been established that karate's top-level performers require a high fitness level. Top-level male karate athletes are typified by low body fat and mesomorphic-ectomorphic somatotype characteristics. Studies dealing with body composition and somatotype of females are scarce. Aerobic capacity has been reported to play a major role in karate performance. It prevents fatigue during training and ensures the recovery processes during rest periods between two subsequent bouts of fighting activity within a fight and between two consecutive matches. It has been established that there is no significant difference between male and female kata (forms) and kumite (sparring/combat) athletes with regard to aerobic performance. Nevertheless, further studies are needed to support these findings. Concerning anaerobic performance, there is a difference in maximal power explored by the force-velocity test between national and international level karatekas (karate practitioners) but, for the maximum accumulated oxygen deficit test there is no difference between them. Muscle explosive power plays a vital role in a karateka's capacity for high-level performance. However, it has been revealed that vertical jump performance, maximal power and maximal velocity differed between national- and international-level karatekas. Moreover, it has been reported that karate performance relies more on muscle power at lower loads rather than higher ones. Thus, karate's decisive actions are essentially dependent on muscle explosive power in both the upper and lower limbs. With regard to dynamic strength, limited research has been conducted. The maximal absolute bench press, half-squat one-repetition maximum and performance of isokinetic tasks differed significantly between highly competitive and novice male karatekas. Studies on female karate athletes do not exist. Concerning flexibility, which is important for the execution of high kicks and adequate range of action at high speeds, it has been demonstrated that karate athletes' ranges of bilateral hip and knee flexion are greater compared with non-karate athletes. Finally, reaction time is a crucial element in karate because high-level performance is based essentially on explosive techniques. A significant difference in the choice reaction time between high-level and novice karatekas exists. Further research is needed concerning the physiological characteristics of female karatekas, the differences between kata and kumite athletes and variations based on weight categories.

Repeat measurements in 69 young adults were performed to assess the test-retest reliability and the 95% confidence interval of the difference in score between paired observations (MDC95) of a Wingate test as abbreviated for field sport participants (test of a 15-second duration [15-secT]). Test-retest reliability was excellent for peak power output (PPO) and mean power output (MPO), independently of their mode of expression and was moderate for the fatigue index (FI). The standard errors of measurement (SEM) for absolute, relative, and derived PPO and MPO values ranged from 2.6 to 3.7%, all being smaller than the corresponding smallest worthwhile change (SWC). In contrast, FI values were rated as "marginal," with an SEM (9.6%) greater than the SWC (1.7). The range of MDC95 values for PPO and MPO were 9.9-10.4 and 7.37-7.42%, respectively. The absolute MPO showed the highest test-retest reliability and was the most effective in detecting real change. A second phase of the study evaluated the criterion-related validity of the 15-secT in 43 young men who performed 15-secT and standard 30-second Wingate anaerobic test (30-secT) in random order, on 2 separate occasions. There were no significant intertest differences in absolute, relative, or derived PPO. However, the FI for the 30-secT was greater than that for the 15-secT. Intertest correlations were highly significant for both MPOs and FIs. These findings suggest that the abbreviated Wingate test offers a reliable and valid tool for the evaluation of PPO and MPO, at least in young physical education students.

This study investigated whether 30 min of acute hot exposure has an additional passive warm-up effect for the improvement in muscle performance in a moderately warm and humid environment. We also sought to determine whether this effect is dependent on the diurnal variation in body temperature. Nine male subjects (age: 31.9 [+/- 5] years, height: 177 [+/- 6] cm, body mass: 69.3 [+/- 10] kg) were tested (CMJ, cycling sprints, and isokinetic contractions of the knee flexors and extensors) in a moderately warm and humid environment (24 [+/- 1] degrees C and 70 [+/- 4] % rh) with and without acute heat exposure (30 min of rest in a sauna at 76 [+/- 2] degrees C and 27 [+/- 1] % rh), both in the morning (07:00 - 09:00 h) and in the evening (17:00 - 19:00 h). Our results indicated a significant effect of both time-of-day and acute heat exposure on leg skin temperature (p < 0.01) but failed to show any effect of time-of-day or acute heat exposure on the various evaluated parameters (CMJ: speed, force, power and height; cycling power: over a half pedal revolution and a total pedal revolution; isokinetic torque: knee extensor and flexor muscles at 4.19 rad x s (-1), 3.14 rad x s (-1), 2.09 rad x s (-1), and 1.05 rad x s (-1)). In conclusion, our data suggest that 30 min of acute hot exposure does not have any passive warm-up effect in a moderately warm and humid environment. Furthermore, the diurnal variation in body temperature has no passive warm-up effect in a moderately warm and humid or in an extremely hot environment.