@misc{RamirezCampilloPerezCastillaThapaetal.2022,
  author    = {Ramirez-Campillo, Rodrigo and P{\´e}rez-Castilla, Alejandro and Thapa, Rohit Kumar and Afonso, Jos{\´e} and Clemente, Filipe Manuel Batista and Colado, Juan C. and Eduardo, Sa{\´e}z de Villarreal and Chaabene, Helmi},
  title     = {Effects of Plyometric Jump Training on Measures of Physical Fitness and Sport-Specific Performance of Water Sports Athletes},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {804},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-57144},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-571441},
  pages     = {27},
  year      = {2022},
  abstract  = {Background A growing body of literature is available regarding the effects of plyometric jump training (PJT) on measures of physical fitness (PF) and sport-specific performance (SSP) in-water sports athletes (WSA, i.e. those competing in sports that are practiced on [e.g. rowing] or in [e.g. swimming; water polo] water). Indeed, incoherent findings have been observed across individual studies making it difficult to provide the scientific community and coaches with consistent evidence. As such, a comprehensive systematic literature search should be conducted to clarify the existent evidence, identify the major gaps in the literature, and offer recommendations for future studies. Aim To examine the effects of PJT compared with active/specific-active controls on the PF (one-repetition maximum back squat strength, squat jump height, countermovement jump height, horizontal jump distance, body mass, fat mass, thigh girth) and SSP (in-water vertical jump, in-water agility, time trial) outcomes in WSA, through a systematic review with meta-analysis of randomized and non-randomized controlled studies. Methods The electronic databases PubMed, Scopus, and Web of Science were searched up to January 2022. According to the PICOS approach, the eligibility criteria were: (population) healthy WSA; (intervention) PJT interventions involving unilateral and/or bilateral jumps, and a minimal duration of ≥ 3 weeks; (comparator) active (i.e. standard sports training) or specific-active (i.e. alternative training intervention) control group(s); (outcome) at least one measure of PF (e.g. jump height) and/or SSP (e.g. time trial) before and after training; and (study design) multi-groups randomized and non-randomized controlled trials. The Physiotherapy Evidence Database (PEDro) scale was used to assess the methodological quality of the included studies. The DerSimonian and Laird random-effects model was used to compute the meta-analyses, reporting effect sizes (ES, i.e. Hedges' g) with 95\% confidence intervals (95\% CIs). Statistical significance was set at p ≤ 0.05. Certainty or confidence in the body of evidence for each outcome was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE), considering its five dimensions: risk of bias in studies, indirectness, inconsistency, imprecision, and risk of publication bias. Results A total of 11,028 studies were identified with 26 considered eligible for inclusion. The median PEDro score across the included studies was 5.5 (moderate-to-high methodological quality). The included studies involved a total of 618 WSA of both sexes (330 participants in the intervention groups [31 groups] and 288 participants in the control groups [26 groups]), aged between 10 and 26 years, and from different sports disciplines such as swimming, triathlon, rowing, artistic swimming, and water polo. The duration of the training programmes in the intervention and control groups ranged from 4 to 36 weeks. The results of the meta-analysis indicated no effects of PJT compared to control conditions (including specific-active controls) for in-water vertical jump or agility (ES =  - 0.15 to 0.03; p = 0.477 to 0.899), or for body mass, fat mass, and thigh girth (ES = 0.06 to 0.15; p = 0.452 to 0.841). In terms of measures of PF, moderate-to-large effects were noted in favour of the PJT groups compared to the control groups (including specific-active control groups) for one-repetition maximum back squat strength, horizontal jump distance, squat jump height, and countermovement jump height (ES = 0.67 to 1.47; p = 0.041 to < 0.001), in addition to a small effect noted in favour of the PJT for SSP time-trial speed (ES = 0.42; p = 0.005). Certainty of evidence across the included studies varied from very low-to-moderate. Conclusions PJT is more effective to improve measures of PF and SSP in WSA compared to control conditions involving traditional sport-specific training as well as alternative training interventions (e.g. resistance training). It is worth noting that the present findings are derived from 26 studies of moderate-to-high methodological quality, low-to-moderate impact of heterogeneity, and very low-to-moderate certainty of evidence based on GRADE. Trial registration The protocol for this systematic review with meta-analysis was published in the Open Science platform (OSF) on January 23, 2022, under the registration doi https://doi.org/10.17605/OSF.IO/NWHS3 (internet archive link: https://archive.org/details/osf-registrations-nwhs3-v1).},
  language  = {en}
}
@misc{ChaabeneBehmNegraetal.2019,
  author    = {Chaabene, Helmi and Behm, David George and Negra, Yassine and Granacher, Urs},
  title     = {Acute Effects of Static Stretching on Muscle Strength and Power},
  series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe},
  number    = {585},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-44003},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440036},
  pages     = {8},
  year      = {2019},
  abstract  = {The effects of static stretching (StS) on subsequent strength and power activities has been one of the most debated topics in sport science literature over the past decades. The aim of this review is (1) to summarize previous and current findings on the acute effects of StS on muscle strength and power performances; (2) to update readers' knowledge related to previous caveats; and (3) to discuss the underlying physiological mechanisms of short-duration StS when performed as single-mode treatment or when integrated into a full warm-up routine. Over the last two decades, StS has been considered harmful to subsequent strength and power performances. Accordingly, it has been recommended not to apply StS before strength- and power-related activities. More recent evidence suggests that when performed as a single-mode treatment or when integrated within a full warm-up routine including aerobic activity, dynamic-stretching, and sport-specific activities, short-duration StS (≤60 s per muscle group) trivially impairs subsequent strength and power activities (∆1-2\%). Yet, longer StS durations (>60 s per muscle group) appear to induce substantial and practically relevant declines in strength and power performances (∆4.0-7.5\%). Moreover, recent evidence suggests that when included in a full warm-up routine, short-duration StS may even contribute to lower the risk of sustaining musculotendinous injuries especially with high-intensity activities (e.g., sprint running and change of direction speed). It seems that during short-duration StS, neuromuscular activation and musculotendinous stiffness appear not to be affected compared with long-duration StS. Among other factors, this could be due to an elevated muscle temperature induced by a dynamic warm-up program. More specifically, elevated muscle temperature leads to increased muscle fiber conduction-velocity and improved binding of contractile proteins (actin, myosin). Therefore, our previous understanding of harmful StS effects on subsequent strength and power activities has to be updated. In fact, short-duration StS should be included as an important warm-up component before the uptake of recreational sports activities due to its potential positive effect on flexibility and musculotendinous injury prevention. However, in high-performance athletes, short-duration StS has to be applied with caution due to its negligible but still prevalent negative effects on subsequent strength and power performances, which could have an impact on performance during competition.},
  language  = {en}
}
@misc{RamirezCampilloGarciaPinillosGarciaRamosetal.2018,
  author    = {Ramirez-Campillo, Rodrigo and Garc{\´i}a-Pinillos, Felipe and Garc{\´i}a-Ramos, Amador and Yanci, Javier and Gentil, Paulo and Chaabene, Helmi and Granacher, Urs},
  title     = {Effects of Different Plyometric Training Frequencies on Components of Physical Fitness in Amateur Female Soccer Players},
  series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {474},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419377},
  pages     = {11},
  year      = {2018},
  abstract  = {Plyometric jump training (PJT) is a frequently used and effective means to improve amateur and elite soccer players' physical fitness. However, it is unresolved how different PJT frequencies per week with equal overall training volume may affect training-induced adaptations. Therefore, the aim of this study was to compare the effects of an in-season 8 week PJT with one session vs. two sessions per week and equal training volume on components of physical fitness in amateur female soccer players. A single-blind randomized controlled trial was conducted. Participants (N = 23; age, 21.4 ± 3.2 years) were randomly assigned to a one session PJT per-week (PJT-1, n = 8), two sessions PJT per-week (PJT-2, n = 8) or an active control group (CON, n = 7). Before and after training, participants performed countermovement jumps (CMJ), drop-jumps from a 20-cm drop-height (DJ20), a maximal kicking velocity test (MKV), the 15-m linear sprint-time test, the Meylan test for the assessment of change of direction ability (CoDA), and the Yo-Yo intermittent recovery endurance test (Yo-YoIR1). Results revealed significant main effects of time for the CMJ, DJ20, MKV, 15-m sprint, CoDA, and the Yo-YoIR1 (all p < 0.001; d = 0.57-0.83). Significant group × time interactions were observed for the CMJ, DJ20, MKV, 15-m sprint, CoDA, and the Yo-YoIR1 (all p < 0.05; d = 0.36-0.51). Post-hoc analyses showed similar improvements for PJT-1 and PJT-2 groups in CMJ (Δ10.6\%, d = 0.37; and Δ10.1\%, d = 0.51, respectively), DJ20 (Δ12.9\%, d = 0.47; and Δ13.1\%, d = 0.54, respectively), MKV (Δ8.6\%, d = 0.52; and Δ9.1\%, d = 0.47, respectively), 15-m sprint (Δ8.3\%, d = 2.25; and Δ9.5\%, d = 2.67, respectively), CoDA (Δ7.5\%, d = 1.68; and Δ7.4\%, d = 1.16, respectively), and YoYoIR1 (Δ10.3\%, d = 0.22; and Δ9.9\%, d = 0.26, respectively). No significant pre-post changes were found for CON (all p > 0.05; Δ0.5-4.2\%, d = 0.03-0.2). In conclusion, higher PJT exposure in terms of session frequency has no extra effects on female soccer players' physical fitness development when jump volume is equated during a short-term (i.e., 8 weeks) training program. From this, it follows that one PJT session per week combined with regular soccer-specific training appears to be sufficient to induce physical fitness improvements in amateur female soccer players.},
  language  = {en}
}
@misc{ELAshkerChaabenePrieske2022,
  author    = {EL-Ashker, Said and Chaabene, Helmi and Prieske, Olaf},
  title     = {Maximal isokinetic elbow and knee flexor-extensor strength measures in combat sports athletes: the role of movement velocity and limb side},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {822},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-58347},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-583475},
  pages     = {10},
  year      = {2022},
  abstract  = {Background Maximal isokinetic strength ratios of joint flexors and extensors are important parameters to indicate the level of muscular balance at the joint. Further, in combat sports athletes, upper and lower limb muscle strength is affected by the type of sport. Thus, this study aimed to examine the differences in maximal isokinetic strength of the flexors and extensors and the corresponding flexor-extensor strength ratios of the elbows and knees in combat sports athletes. Method Forty male participants (age = 22.3 ± 2.5 years) from four different combat sports (amateur boxing, taekwondo, karate, and judo; n = 10 per sport) were tested for eccentric peak torque of the elbow/knee flexors (EF/KF) and concentric peak torque of the elbow/knee extensors (EE/KE) at three different angular velocities (60, 120, and 180°/s) on the dominant and non-dominant side using an isokinetic device. Results Analyses revealed significant, large-sized group × velocity × limb interactions for EF, EE, and EF-EE ratio, KF, KE, and KF-KE ratio (p ≤ 0.03; 0.91 ≤ d ≤ 1.75). Post-hoc analyses indicated that amateur boxers displayed the largest EE strength values on the non-dominant side at ≤ 120°/s and the dominant side at ≥ 120°/s (p < 0.03; 1.21 ≤ d ≤ 1.59). The largest EF-EE strength ratios were observed on amateur boxers' and judokas' non-dominant side at ≥ 120°/s (p < 0.04; 1.36 ≤ d ≤ 2.44). Further, we found lower KF-KE strength measures in karate (p < 0.04; 1.12 ≤ d ≤ 6.22) and judo athletes (p ≤ 0.03; 1.60 ≤ d ≤ 5.31) particularly on the non-dominant side. Conclusions The present findings indicated combat sport-specific differences in maximal isokinetic strength measures of EF, EE, KF, and KE particularly in favor of amateur boxers on the non-dominant side.},
  language  = {en}
}
@misc{NevillNegraMyersetal.2021,
  author    = {Nevill, Alan M. and Negra, Yassine and Myers, Tony D. and Duncan, Michael J. and Chaabene, Helmi and Granacher, Urs},
  title     = {Are Early or Late Maturers Likely to Be Fitter in the General Population?},
  series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {695},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-48992},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-489928},
  pages     = {18},
  year      = {2021},
  abstract  = {The present study aims to identify the optimal body-size/shape and maturity characteristics associated with superior fitness test performances having controlled for body-size, sex, and chronological-age differences. The sample consisted of 597 Tunisian children (396 boys and 201 girls) aged 8 to 15 years. Three sprint speeds recorded at 10, 20 and 30 m; two vertical and two horizontal jump tests; a change-of-direction and a handgrip-strength tests, were assessed during physical-education classes. Allometric modelling was used to identify the benefit of being an early or late maturer. Findings showed that being tall and light is the ideal shape to be successful at most physical fitness tests, but the height-to-weight "shape" ratio seems to be test-dependent. Having controlled for body-size/shape, sex, and chronological age, the model identified maturity-offset as an additional predictor. Boys who go earlier/younger through peak-height-velocity (PHV) outperform those who go at a later/older age. However, most of the girls' physical-fitness tests peaked at the age at PHV and decline thereafter. Girls whose age at PHV was near the middle of the age range would appear to have an advantage compared to early or late maturers. These findings have important implications for talent scouts and coaches wishing to recruit children into their sports/athletic clubs.},
  language  = {en}
}
@misc{ElAshkerChaabenePrieskeetal.2019,
  author    = {El-Ashker, Said and Chaabene, Helmi and Prieske, Olaf and Abdelkafy, Ashraf and Ahmed, Mohamed A. and Muaidi, Qassim I. and Granacher, Urs},
  title     = {Effects of Neuromuscular Fatigue on Eccentric Strength and Electromechanical Delay of the Knee Flexors},
  series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe},
  number    = {562},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-43586},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435863},
  pages     = {9},
  year      = {2019},
  abstract  = {Purpose: To examine the effects of fatiguing isometric contractions on maximal eccentric strength and electromechanical delay (EMD) of the knee flexors in healthy young adults of different training status. Methods: Seventy-five male participants (27.7 ± 5.0 years) were enrolled in this study and allocated to three experimental groups according to their training status: athletes (ATH, n = 25), physically active adults (ACT, n = 25), and sedentary participants (SED, n = 25). The fatigue protocol comprised intermittent isometric knee flexions (6-s contraction, 4-s rest) at 60\% of the maximum voluntary contraction until failure. Pre- and post-fatigue, maximal eccentric knee flexor strength and EMDs of the biceps femoris, semimembranosus, and semitendinosus muscles were assessed during maximal eccentric knee flexor actions at 60, 180, and 300°/s angular velocity. An analysis of covariance was computed with baseline (unfatigued) data included as a covariate. Results: Significant and large-sized main effects of group (p ≤ 0.017, 0.87 ≤ d ≤ 3.69) and/or angular velocity (p < 0.001, d = 1.81) were observed. Post hoc tests indicated that regardless of angular velocity, maximal eccentric knee flexor strength was lower and EMD was longer in SED compared with ATH and ACT (p ≤ 0.025, 0.76 ≤ d ≤ 1.82) and in ACT compared with ATH (p = ≤0.025, 0.76 ≤ d ≤ 1.82). Additionally, EMD at post-test was significantly longer at 300°/s compared with 60 and 180°/s (p < 0.001, 2.95 ≤ d ≤ 4.64) and at 180°/s compared with 60°/s (p < 0.001, d = 2.56), irrespective of training status. Conclusion: The main outcomes revealed significantly higher maximal eccentric strength and shorter eccentric EMDs of knee flexors in individuals with higher training status (i.e., athletes) following fatiguing exercises. Therefore, higher training status is associated with better neuromuscular functioning (i.e., strength, EMD) of the hamstring muscles in fatigued condition. Future longitudinal studies are needed to substantiate the clinical relevance of these findings.},
  language  = {en}
}
@misc{SammoudNegraBouguezzietal.2020,
  author    = {Sammoud, Senda and Negra, Yassine and Bouguezzi, Raja and Hachana, Younes and Granacher, Urs and Chaabene, Helmi},
  title     = {The effects of plyometric jump training on jump and sport-specific performances in prepubertal female swimmers},
  series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {658},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-47827},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-478272},
  pages     = {9},
  year      = {2020},
  abstract  = {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 (PJTG; 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 PJTG (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.},
  language  = {en}
}