TY - JOUR A1 - Fernandez-Fernandez, Jaime A1 - Granacher, Urs A1 - Martinez-Martin, Isidoro A1 - Garcia-Tormo, José Vicente A1 - Herrero-Molleda, Alba A1 - Barbado, David A1 - García López, Juan T1 - Physical fitness and throwing speed in U13 versus U15 male handball players JF - BMC Sports Science, Medicine and Rehabilitation N2 - Background The aim of this study was to analyze the shoulder functional profile (rotation range of motion [ROM] and strength), upper and lower body performance, and throwing speed of U13 versus U15 male handball players, and to establish the relationship between these measures of physical fitness and throwing speed. Methods One-hundred and nineteen young male handball players (under (U)-13 (U13) [n = 85]) and U15 [n = 34]) volunteered to participate in this study. The participating athletes had a mean background of sytematic handball training of 5.5 ± 2.8 years and they exercised on average 540 ± 10.1 min per week including sport-specific team handball training and strength and conditioning programs. Players were tested for passive shoulder range-of-motion (ROM) for both internal (IR) and external rotation (ER) and isometric strength (i.e., IR and ER) of the dominant/non-dominant shoulders, overhead medicine ball throw (OMB), hip isometric abductor (ABD) and adductor (ADD) strength, hip ROM, jumps (countermovement jump [CMJ] and triple leg-hop [3H] for distance), linear sprint test, modified 505 change-of-direction (COD) test and handball throwing speed (7 m [HT7] and 9 m [HT9]). Results U15 players outperformed U13 in upper (i.e., HT7 and HT9 speed, OMB, absolute IR and ER strength of the dominant and non-dominant sides; Cohen’s d: 0.76–2.13) and lower body (i.e., CMJ, 3H, 20-m sprint and COD, hip ABD and ADD; d: 0.70–2.33) performance measures. Regarding shoulder ROM outcomes, a lower IR ROM was found of the dominant side in the U15 group compared to the U13 and a higher ER ROM on both sides in U15 (d: 0.76–1.04). It seems that primarily anthropometric characteristics (i.e., body height, body mass) and upper body strength/power (OMB distance) are the most important factors that explain the throw speed variance in male handball players, particularly in U13. Conclusions Findings from this study imply that regular performance monitoring is important for performance development and for minimizing injury risk of the shoulder in both age categories of young male handball players. Besides measures of physical fitness, anthropometric data should be recorded because handball throwing performance is related to these measures. KW - Overhead athletes KW - Shoulder KW - Injury risk KW - Sport-specific performance Y1 - 2022 U6 - https://doi.org/10.1186/s13102-022-00507-0 SN - 1758-2555 VL - 14 PB - Springer CY - London ER - TY - JOUR A1 - Jararnezhadgero, AmirAli A1 - Mamashli, Elaheh A1 - Granacher, Urs T1 - An Endurance-Dominated Exercise Program Improves Maximum Oxygen Consumption, Ground Reaction Forces, and Muscle Activities in Patients With Moderate Diabetic Neuropathy JF - Frontiers in physiology / Frontiers Research Foundation N2 - Background: The prevalence of diabetes worldwide is predicted to increase from 2.8% in 2000 to 4.4% in 2030. Diabetic neuropathy (DN) is associated with damage to nerve glial cells, their axons, and endothelial cells leading to impaired function and mobility. Objective: We aimed to examine the effects of an endurance-dominated exercise program on maximum oxygen consumption (VO2max), ground reaction forces, and muscle activities during walking in patients with moderate DN. Methods: Sixty male and female individuals aged 45–65 years with DN were randomly assigned to an intervention (IG, n = 30) or a waiting control (CON, n = 30) group. The research protocol of this study was registered with the Local Clinical Trial Organization (IRCT20200201046326N1). IG conducted an endurance-dominated exercise program including exercises on a bike ergometer and gait therapy. The progressive intervention program lasted 12 weeks with three sessions per week, each 40–55 min. CON received the same treatment as IG after the post-tests. Pre- and post-training, VO2max was tested during a graded exercise test using spiroergometry. In addition, ground reaction forces and lower limbs muscle activities were recorded while walking at a constant speed of ∼1 m/s. Results: No statistically significant baseline between group differences was observed for all analyzed variables. Significant group-by-time interactions were found for VO2max (p < 0.001; d = 1.22). The post-hoc test revealed a significant increase in IG (p < 0.001; d = 1.88) but not CON. Significant group-by-time interactions were observed for peak lateral and vertical ground reaction forces during heel contact and peak vertical ground reaction force during push-off (p = 0.001–0.037; d = 0.56–1.53). For IG, post-hoc analyses showed decreases in peak lateral (p < 0.001; d = 1.33) and vertical (p = 0.004; d = 0.55) ground reaction forces during heel contact and increases in peak vertical ground reaction force during push-off (p < 0.001; d = 0.92). In terms of muscle activity, significant group-by-time interactions were found for vastus lateralis and gluteus medius during the loading phase and for vastus medialis during the mid-stance phase, and gastrocnemius medialis during the push-off phase (p = 0.001–0.044; d = 0.54–0.81). Post-hoc tests indicated significant intervention-related increases in vastus lateralis (p = 0.001; d = 1.08) and gluteus medius (p = 0.008; d = 0.67) during the loading phase and vastus medialis activity during mid-stance (p = 0.001; d = 0.86). In addition, post-hoc tests showed decreases in gastrocnemius medialis during the push-off phase in IG only (p < 0.001; d = 1.28). Conclusions: This study demonstrated that an endurance-dominated exercise program has the potential to improve VO2max and diabetes-related abnormal gait in patients with DN. The observed decreases in peak vertical ground reaction force during the heel contact of walking could be due to increased vastus lateralis and gluteus medius activities during the loading phase. Accordingly, we recommend to implement endurance-dominated exercise programs in type 2 diabetic patients because it is feasible, safe and effective by improving aerobic capacity and gait characteristics. KW - oxygen consumption KW - kinetics KW - electromyography KW - diabetic KW - gait Y1 - 2021 U6 - https://doi.org/10.3389/fphys.2021.654755 SN - 1664-042X VL - 12 SP - 1 EP - 15 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Ahmadi, Hamid A1 - Herat, Nehara A1 - Alizadeh, Shahab A1 - Button, Duane C. A1 - Granacher, Urs A1 - Behm, David G. T1 - Effect of an inverted seated position with upper arm blood flow restriction on measures of elbow flexors neuromuscular performance JF - PLOS ONE / Public Library of Science N2 - Purpose The objective of the investigation was to determine the concomitant effects of upper arm blood flow restriction (BFR) and inversion on elbow flexors neuromuscular responses. Methods Randomly allocated, 13 volunteers performed four conditions in a within-subject design: rest (control, 1-min upright position without BFR), control (1-min upright with BFR), 1-min inverted (without BFR), and 1-min inverted with BFR. Evoked and voluntary contractile properties, before, during and after a 30-s maximum voluntary contraction (MVC) exercise intervention were examined as well as pain scale. Results Inversion induced significant pre-exercise intervention decreases in elbow flexors MVC (21.1%, Z2p = 0.48, p = 0.02) and resting evoked twitch forces (29.4%, Z2p = 0.34, p = 0.03). The 30-s MVC induced significantly greater pre- to post-test decreases in potentiated twitch force (Z2p = 0.61, p = 0.0009) during inversion (75%) than upright (65.3%) conditions. Overall, BFR decreased MVC force 4.8% (Z2p = 0.37, p = 0.05). For upright position, BFR induced 21.0% reductions in M-wave amplitude (Z2p = 0.44, p = 0.04). There were no significant differences for electromyographic activity or voluntary activation as measured with the interpolated twitch technique. For all conditions, there was a significant increase in pain scale between the 40-60 s intervals and post-30-s MVC (upright< inversion, and without BFR< BFR). Conclusion The concomitant application of inversion with elbow flexors BFR only amplified neuromuscular performance impairments to a small degree. Individuals who execute forceful contractions when inverted or with BFR should be cognizant that force output may be impaired. Y1 - 2021 U6 - https://doi.org/10.1371/journal.pone.0245311 SN - 1932-6203 VL - 16 IS - 5 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Arazi, Hamid A1 - Asadi, Abbas A1 - Khalkhali, Farhood A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players BT - A Preliminary Study JF - Frontiers in Physiology N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season. KW - training load KW - rate of perceived exertion KW - rolling averages KW - weighted moving averages KW - football Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00995 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Prieske, Olaf A1 - Chaabene, Helmi A1 - Gäbler, Martijn A1 - Herz, Michael A1 - Helm, Norman A1 - Markov, Adrian A1 - Granacher, Urs T1 - Seasonal changes in anthropometry, body composition, and physical fitness and the relationships with sporting success in young sub-elite judo athletes BT - an exploratory study JF - International journal of environmental research and public health : IJERPH N2 - This exploratory study aimed to monitor long-term seasonal developments in measures of anthropometry, body composition, and physical fitness in young judo athletes, and to compute associations between these measures and sporting success. Forty-four young judoka (20 females, 24 males) volunteered to participate. Tests for the assessment of anthropometry (e.g., body height/mass), body-composition (e.g., lean body mass), muscle strength (isometric handgrip strength), vertical jumping (e.g., countermovement-jump (CMJ) height), and dynamic balance (Y-balance test) were conducted at the beginning and end of a 10-month training season. Additionally, sporting success at the end of the season was recorded for each athlete. Analyses revealed significant time x sex interaction effects for lean-body-mass, isometric handgrip strength, and CMJ height (0.7 <= d <= 1.6). Post-hoc analyses showed larger gains for all measures in young males (1.9 <= d <= 6.0) compared with females (d = 2.4) across the season. Additionally, significant increases in body height and mass as well as Y-balance test scores were found from pre-to-post-test (1.2 <= d <= 4.3), irrespective of sex. Further, non-significant small-to-moderate-sized correlations were identified between changes in anthropometry/body composition/physical fitness and sporting success (p > 0.05; -0.34 <= rho <= 0.32). Regression analysis confirmed that no model significantly predicted sporting success. Ten months of judo training and/or growth/maturation contributed to significant changes in anthropometry, body composition, and physical fitness, particularly in young male judo athletes. KW - combat sports KW - periodization KW - somatic variables KW - training load KW - training KW - monitoring KW - young athletes Y1 - 2020 U6 - https://doi.org/10.3390/ijerph17197169 SN - 1660-4601 VL - 17 IS - 19 PB - MDPI AG CY - Basel ER - TY - JOUR A1 - Kasmi, Sofien A1 - Zouhal, Hassane A1 - Hammami, Raouf A1 - Clark, Cain Craig Truman A1 - Hackney, Anthony C. A1 - Hammami, Amri A1 - Chtara, Moktar A1 - Chortane, Sabri Gaied A1 - Ben Salah, Fatma Zohra A1 - Granacher, Urs A1 - Ben Ounis, Omar T1 - The Effects of Eccentric and Plyometric Training Programs and Their Combination on Stability and the Functional Performance in the Post-ACL-Surgical Rehabilitation Period of Elite Female Athletes JF - Frontiers in physiology N2 - Background: The standard method to treat physically active patients with anterior cruciate ligament (ACL) rupture is ligament reconstruction surgery. The rehabilitation training program is very important to improve functional performance in recreational athletes following ACL reconstruction. Objectives: The aims of this study were to compare the effects of three different training programs, eccentric training (ECC), plyometric training (PLYO), or combined eccentric and plyometric training (COMB), on dynamic balance (Y-BAL), the Lysholm Knee Scale (LKS), the return to sport index (RSI), and the leg symmetry index (LSI) for the single leg hop test for distance in elite female athletes after ACL surgery. Materials and Methods: Fourteen weeks after rehabilitation from surgery, 40 elite female athletes (20.3 ± 3.2 years), who had undergone an ACL reconstruction, participated in a short-term (6 weeks; two times a week) training study. All participants received the same rehabilitation protocol prior to the training study. Athletes were randomly assigned to three experimental groups, ECC (n = 10), PLYO (n = 10), and COMB (n = 10), and to a control group (CON: n = 10). Testing was conducted before and after the 6-week training programs and included the Y-BAL, LKS, and RSI. LSI was assessed after the 6-week training programs only. Results: Adherence rate was 100% across all groups and no training or test-related injuries were reported. No significant between-group baseline differences (pre-6-week training) were observed for any of the parameters. Significant group-by-time interactions were found for Y-BAL (p < 0.001, ES = 1.73), LKS (p < 0.001, ES = 0.76), and RSI (p < 0.001, ES = 1.39). Contrast analysis demonstrated that COMB yielded significantly greater improvements in Y-BAL, LKS, and RSI (all p < 0.001), in addition to significantly better performances in LSI (all p < 0.001), than CON, PLYO, and ECC, respectively. Conclusion: In conclusion, combined (eccentric/plyometric) training seems to represent the most effective training method as it exerts positive effects on both stability and functional performance in the post-ACL-surgical rehabilitation period of elite female athletes. KW - return-to-sport KW - anterior cruciate ligament KW - eccentric-plyometric KW - training KW - stability KW - functional performance Y1 - 2021 U6 - https://doi.org/10.3389/fphys.2021.688385 SN - 1664-042X VL - 12 SP - 1 EP - 11 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Delfan, Maryam A1 - Vahed, Alieh A1 - Bishop, David A1 - Juybari, Raheleh Amadeh A1 - Laher, Ismail A1 - Saeidi, Ayoub A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Effects of two workload-matched high-intensity interval training protocols on regulatory factors associated with mitochondrial biogenesis in the soleus muscle of diabetic rats JF - Frontiers in Physiology N2 - Aims: High intensity interval training (HIIT) improves mitochondrial characteristics. This study compared the impact of two workload-matched high intensity interval training (HIIT) protocols with different work:recovery ratios on regulatory factors related to mitochondrial biogenesis in the soleus muscle of diabetic rats. Materials and methods: Twenty-four Wistar rats were randomly divided into four equal-sized groups: non-diabetic control, diabetic control (DC), diabetic with long recovery exercise [4–5 × 2-min running at 80%–90% of the maximum speed reached with 2-min of recovery at 40% of the maximum speed reached (DHIIT1:1)], and diabetic with short recovery exercise (5–6 × 2-min running at 80%–90% of the maximum speed reached with 1-min of recovery at 30% of the maximum speed reached [DHIIT2:1]). Both HIIT protocols were completed five times/week for 4 weeks while maintaining equal running distances in each session. Results: Gene and protein expressions of PGC-1α, p53, and citrate synthase of the muscles increased significantly following DHIIT1:1 and DHIIT2:1 compared to DC (p ˂ 0.05). Most parameters, except for PGC-1α protein (p = 0.597), were significantly higher in DHIIT2:1 than in DHIIT1:1 (p ˂ 0.05). Both DHIIT groups showed significant increases in maximum speed with larger increases in DHIIT2:1 compared with DHIIT1:1. Conclusion: Our findings indicate that both HIIT protocols can potently up-regulate gene and protein expression of PGC-1α, p53, and CS. However, DHIIT2:1 has superior effects compared with DHIIT1:1 in improving mitochondrial adaptive responses in diabetic rats. KW - diabetes mellitus KW - muscle metabolism KW - time-efficient exercise KW - mitochondrial adaptation KW - exercise training Y1 - 2022 U6 - https://doi.org/10.3389/fphys.2022.927969 SN - 1664-042X SP - 1 EP - 12 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Ramachandran, Akhilesh Kumar A1 - Singh, Utkarsh A1 - Ramirez-Campillo, Rodrigo A1 - Clemente, Filipe Manuel A1 - Afonso, José A1 - Granacher, Urs T1 - Effects of Plyometric Jump Training on Balance Performance in Healthy Participants: A Systematic Review With Meta-Analysis / Effects of plyometric-jump training on balance performance in healthy individuals across the lifespan: A systematic review with meta-analysisist JF - Frontiers in Physiology N2 - Postural balance represents a fundamental movement skill for the successful performance of everyday and sport-related activities. There is ample evidence on the effectiveness of balance training on balance performance in athletic and non-athletic population. However, less is known on potential transfer effects of other training types, such as plyometric jump training (PJT) on measures of balance. Given that PJT is a highly dynamic exercise mode with various forms of jump-landing tasks, high levels of postural control are needed to successfully perform PJT exercises. Accordingly, PJT has the potential to not only improve measures of muscle strength and power but also balance. To systematically review and synthetize evidence from randomized and non-randomized controlled trials regarding the effects of PJT on measures of balance in apparently healthy participants. Systematic literature searches were performed in the electronic databases PubMed, Web of Science, and SCOPUS. A PICOS approach was applied to define inclusion criteria, (i) apparently healthy participants, with no restrictions on their fitness level, sex, or age, (ii) a PJT program, (iii) active controls (any sport-related activity) or specific active controls (a specific exercise type such as balance training), (iv) assessment of dynamic, static balance pre- and post-PJT, (v) randomized controlled trials and controlled trials. The methodological quality of studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. This meta-analysis was computed using the inverse variance random-effects model. The significance level was set at p <0.05. The initial search retrieved 8,251 plus 23 records identified through other sources. Forty-two articles met our inclusion criteria for qualitative and 38 for quantitative analysis (1,806 participants [990 males, 816 females], age range 9–63 years). PJT interventions lasted between 4 and 36 weeks. The median PEDro score was 6 and no study had low methodological quality (≤3). The analysis revealed significant small effects of PJT on overall (dynamic and static) balance (ES = 0.46; 95% CI = 0.32–0.61; p < 0.001), dynamic (e.g., Y-balance test) balance (ES = 0.50; 95% CI = 0.30–0.71; p < 0.001), and static (e.g., flamingo balance test) balance (ES = 0.49; 95% CI = 0.31–0.67; p < 0.001). The moderator analyses revealed that sex and/or age did not moderate balance performance outcomes. When PJT was compared to specific active controls (i.e., participants undergoing balance training, whole body vibration training, resistance training), both PJT and alternative training methods showed similar effects on overall (dynamic and static) balance (p = 0.534). Specifically, when PJT was compared to balance training, both training types showed similar effects on overall (dynamic and static) balance (p = 0.514). Conclusion: Compared to active controls, PJT showed small effects on overall balance, dynamic and static balance. Additionally, PJT produced similar balance improvements compared to other training types (i.e., balance training). Although PJT is widely used in athletic and recreational sport settings to improve athletes' physical fitness (e.g., jumping; sprinting), our systematic review with meta-analysis is novel in as much as it indicates that PJT also improves balance performance. The observed PJT-related balance enhancements were irrespective of sex and participants' age. Therefore, PJT appears to be an adequate training regime to improve balance in both, athletic and recreational settings. KW - plyometric exercise KW - human physical conditioning KW - resistance training KW - postural control KW - exercise KW - movement Y1 - 2021 SN - 1664-042X VL - 12 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Jafarnezhadgero, Amir Ali A1 - Noroozi, Raha A1 - Fakhri, Ehsan A1 - Granacher, Urs A1 - Oliveira, Anderson Souza T1 - The Impact of COVID-19 and muscle fatigue on cardiorespiratory fitness and running kinetics in female recreational runners JF - Frontiers in physiology N2 - Background: There is evidence that fully recovered COVID-19 patients usually resume physical exercise, but do not perform at the same intensity level performed prior to infection. The aim of this study was to evaluate the impact of COVID-19 infection and recovery as well as muscle fatigue on cardiorespiratory fitness and running biomechanics in female recreational runners. Methods: Twenty-eight females were divided into a group of hospitalized and recovered COVID-19 patients (COV, n = 14, at least 14 days following recovery) and a group of healthy age-matched controls (CTR, n = 14). Ground reaction forces from stepping on a force plate while barefoot overground running at 3.3 m/s was measured before and after a fatiguing protocol. The fatigue protocol consisted of incrementally increasing running speed until reaching a score of 13 on the 6-20 Borg scale, followed by steady-state running until exhaustion. The effects of group and fatigue were assessed for steady-state running duration, steady-state running speed, ground contact time, vertical instantaneous loading rate and peak propulsion force. Results: COV runners completed only 56% of the running time achieved by the CTR (p < 0.0001), and at a 26% slower steady-state running speed (p < 0.0001). There were fatigue-related reductions in loading rate (p = 0.004) without group differences. Increased ground contact time (p = 0.002) and reduced peak propulsion force (p = 0.005) were found for COV when compared to CTR. Conclusion: Our results suggest that female runners who recovered from COVID-19 showed compromised running endurance and altered running kinetics in the form of longer stance periods and weaker propulsion forces. More research is needed in this area using larger sample sizes to confirm our study findings. KW - hospitalization KW - running mechanics KW - ground reaction forces KW - virus KW - infection KW - COVID-19 Y1 - 2022 U6 - https://doi.org/10.3389/fphys.2022.942589 SN - 1664-042X VL - 13 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Thiele, Dirk A1 - Prieske, Olaf A1 - Lesinski, Melanie A1 - Granacher, Urs T1 - Effects of Equal Volume Heavy-Resistance Strength Training Versus Strength Endurance Training on Physical Fitness and Sport-Specific Performance in Young Elite Female Rowers JF - Frontiers in Physiology N2 - Strength training is an important means for performance development in young rowers. The purpose of this study was to examine the effects of a 9-week equal volume heavy-resistance strength training (HRST) versus strength endurance training (SET) in addition to regular rowing training on primary (e.g., maximal strength/power) and secondary outcomes (e.g., balance) in young rowers. Twenty-six female elite adolescent rowers were assigned to an HRST (n = 12; age: 13.2 ± 0.5 yrs; maturity-offset: +2.0 ± 0.5 yrs) or a SET group (n = 14; age: 13.1 ± 0.5 yrs; maturity-offset: +2.1 ± 0.5 yrs). HRST and SET comprised lower- (i.e., leg press/knee flexion/extension), upper-limbs (i.e., bench press/pull; lat-pull down), and complex exercises (i.e., rowing ergometer). HRST performed four sets with 12 repetitions per set at an intensity of 75–95% of the one-repetition maximum (1-RM). SET conducted four sets with 30 repetitions per set at 50–60% of the 1-RM. Training volume was matched for overall repetitions × intensity × training per week. Pre-post training, tests were performed for the assessment of primary [i.e., maximal strength (e.g., bench pull/knee flexion/extension 1-RM/isometric handgrip test), muscle power (e.g., medicine-ball push test, triple hop, drop jump, and countermovement jump), anaerobic endurance (400-m run), sport-specific performance (700-m rowing ergometer trial)] and secondary outcomes [dynamic balance (Y-balance test), change-of-direction (CoD) speed (multistage shuttle-run test)]. Adherence rate was >87% and one athlete of each group dropped out. Overall, 24 athletes completed the study and no test or training-related injuries occurred. Significant group × time interactions were observed for maximal strength, muscle power, anaerobic endurance, CoD speed, and sport-specific performance (p ≤ 0.05; 0.45 ≤ d ≤ 1.11). Post hoc analyses indicated larger gains in maximal strength and muscle power following HRST (p ≤ 0.05; 1.81 ≤ d ≤ 3.58) compared with SET (p ≤ 0.05; 1.04 ≤ d ≤ 2.30). Furthermore, SET (p ≤ 0.01; d = 2.08) resulted in larger gains in sport-specific performance compared with HRST (p < 0.05; d = 1.3). Only HRST produced significant pre-post improvements for anaerobic endurance and CoD speed (p ≤ 0.05; 1.84 ≤ d ≤ 4.76). In conclusion, HRST in addition to regular rowing training was more effective than SET to improve selected measures of physical fitness (i.e., maximal strength, muscle power, anaerobic endurance, and CoD speed) and SET was more effective than HRST to enhance sport-specific performance gains in female elite young rowers. KW - concurrent training KW - plyometric training KW - on-water performance KW - race time KW - oarsmen Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00888 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Chaabene, Helmi A1 - Lesinski, Melanie A1 - Behm, David George A1 - Granacher, Urs T1 - Performance- and healthrelated benefits of youth resistance training T1 - Leistungs- und gesundheitsbezogene Wirkungen von Krafttraining mit Heranwachsenden JF - Sports Orthopaedics and Traumatology N2 - Performance- and healthrelated benefits of yoThere is ample evidence that youth resistance training (RT) is safe, joyful, and effective for different markers of performance (e.g., muscle strength, power, linear sprint speed) and health (e.g., injury prevention). Accordingly, the first aim of this narrative review is to present and discuss the relevance of muscle strength for youth physical development. The second purpose is to report evidence on the effectiveness of RT on muscular fitness (muscle strength, power, muscle endurance), on movement skill performance and injury prevention in youth. There is evidence that RT is effective in enhancing measures of muscle fitness in children and adolescents, irrespective of sex. Additionally, numerous studies indicate that RT has positive effects on fundamental movement skills (e.g., jumping, running, throwing) in youth regardless of age, maturity, training status, and sex. Further, irrespective of age, sex, and training status, regular exposure to RT (e.g., plyometric training) decreases the risk of sustaining injuries in youth. This implies that RT should be a meaningful element of youths’ exercise programming. This has been acknowledged by global (e.g., World Health Organization) and national (e.g., National Strength and Conditioning Association) health- and performance-related organizations which is why they recommended to perform RT as an integral part of weekly exercise programs to promote muscular strength, fundamental movement skills, and to resist injuries in youth.uth resistance training N2 - Die aktuelle Literatur zum Krafttraining mit Kindern und Jugendlichen zeigt eindrücklich, dass ein altersgerechtes und fachlich angeleitetes Krafttraining eine sichere, freudvolle und effektive Maßnahme für die Leistungsentwicklung (z. B. Muskelkraft, Schnellkraft, Sprintgeschwindigkeit) und Gesundheitserhaltung (z. B. Verletzungsprävention) von Heranwachsenden darstellt. Einerseits ist es das Ziel dieses narrativen Übersichtsartikels, die Relevanz der Muskelkraft für die körperliche Entwicklung von Heranwachsenden zu diskutieren. Andererseits sollen aktuelle Befunde zur Effektivität von Krafttraining auf die muskuläre Fitness (Maximal-/Schnellkraft, Kraftausdauer), elementare Bewegungsfertigkeiten (z.B. Springen, Rennen, Werfen) sowie die Verletzungsprävention bei Kindern und Jugendlichen beschrieben werden. Die aktuelle Literatur belegt, dass Krafttraining die Muskelkraft, die Schnellkraft und die Kraftausdauer von Kindern und Jugendlichen unabhängig vom Geschlecht verbessern kann. Weiterhin zeigen Studien, dass trainingsbedingte Verbesserungen der muskulären Fitness auf elementare Bewegungsfertigkeiten transferieren. Diese Wirkungen sind unabhängig vom Alter, der biologischen Reife, dem Trainingsstatus und dem Geschlecht der Trainierenden. Zudem verringert regelmäßiges Krafttraining das Verletzungsrisiko der Heranwachsenden unabhängig von Alter, Geschlecht und Trainingsstatus. Aufgrund dieses breiten Wirkungsspektrums sollte Krafttraining ein elementarer Bestandteil des Trainings von Heranwachsenden darstellen. Nationale (National Strength and Conditioning Association) sowie internationale (Weltgesundheitsorganisation) gesundheits- und leistungsorientierte Standesgesellschaften haben die positiven Wirkungen von Krafttraining erkannt und in ihre Bewegungsempfehlungen für Kinder und Jugendliche übernommen. KW - muscle strength KW - muscle power KW - strength training KW - children KW - adolescents KW - Maximalkraft KW - Schnellkraft KW - Widerstandstraining KW - Kinder KW - Jugendliche Y1 - 2020 VL - 36 IS - 3 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nobari, Hadi A1 - Mahmoudzadeh Khalili, Sara A1 - Denche Zamorano, Angel Manuel A1 - Bowman, ‪Thomas G. A1 - Granacher, Urs T1 - Workload is associated with the occurrence of non-contact injuries in professional male soccer players: A pilot study JF - Frontiers in Psychology N2 - Injuries in professional soccer are a significant concern for teams, and they are caused amongst others by high training load. This cohort study describes the relationship between workload parameters and the occurrence of non-contact injuries, during weeks with high and low workload in professional soccer players throughout the season. Twenty-one professional soccer players aged 28.3 ± 3.9 yrs. who competed in the Iranian Persian Gulf Pro League participated in this 48-week study. The external load was monitored using global positioning system (GPS, GPSPORTS Systems Pty Ltd) and the type of injury was documented daily by the team's medical staff. Odds ratio (OR) and relative risk (RR) were calculated for non-contact injuries for high- and low-load weeks according to acute (AW), chronic (CW), acute to chronic workload ratio (ACWR), and AW variation (Δ-Acute) values. By using Poisson distribution, the interval between previous and new injuries were estimated. Overall, 12 non-contact injuries occurred during high load and 9 during low load weeks. Based on the variables ACWR and Δ-AW, there was a significantly increased risk of sustaining non-contact injuries (p < 0.05) during high-load weeks for ACWR (OR: 4.67), and Δ-AW (OR: 4.07). Finally, the expected time between injuries was significantly shorter in high load weeks for ACWR [1.25 vs. 3.33, rate ratio time (RRT)] and Δ-AW (1.33 vs. 3.45, RRT) respectively, compared to low load weeks. The risk of sustaining injuries was significantly larger during high workload weeks for ACWR, and Δ-AW compared with low workload weeks. The observed high OR in high load weeks indicate that there is a significant relationship between workload and occurrence of non-contact injuries. The predicted time to new injuries is shorter in high load weeks compared to low load weeks. Therefore, the frequency of injuries is higher during high load weeks for ACWR and Δ-AW. ACWR and Δ-AW appear to be good indicators for estimating the injury risk, and the time interval between injuries. KW - ACWR KW - external load KW - football KW - prevention KW - performance KW - injury risk Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.925722 SN - 1664-1078 SP - 1 EP - 9 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Haile, Sarah R. A1 - Fühner, Thea Heidi A1 - Granacher, Urs A1 - Stocker, Julien A1 - Radtke, Thomas A1 - Kriemler, Susi T1 - Reference values and validation of the 1-minute sit-to-stand test in healthy 5-16-year-old youth BT - a cross-sectional study JF - BMJ open N2 - Objectives: It is essential to have simple, reliable and valid tests to measure children's functional capacity in schools or medical practice. The 1-minute sit-to-stand (STS) test is a quick fitness test requiring little equipment or space that is increasingly used in both healthy populations and those with chronic disease. We aimed to provide age-specific and sex-specific reference values of STS test in healthy children and adolescents and to evaluate its short-term reliability and construct validity. Design setting and participants: Cross-sectional convenience sample from six public schools and one science fair in central Europe. Overall, 587 healthy participants aged 5-16 years were recruited and divided into age groups of 3 years each. Outcomes: 1-minute STS. To evaluate short-term reliability, some children performed the STS test twice. To evaluate construct validity, some children also performed a standing long jump (SLJ) and a maximal incremental exercise test. Results: Data from 547 youth aged 5-16 years were finally included in the analyses. The median number of repetitions in 1 min in males (females) ranged from 55 [95% CI: 38 to 72] (53 [95% CI: 35 to 76]) in 14-16-year olds to 59 [95% CI: 41 to 77] (60 [95% CI: 38 to 77]) in 8-10-year olds. Children who repeated STS showed a learning effect of on average 4.8 repetitions more than the first test (95% limits of agreement: -6.7 to 16.4). Moderate correlations were observed between the STS and the SLJ (r=0.48) tests and the maximal exercise test (r=0.43). Conclusions: The reported STS reference values can be used to interpret STS test performance in children and adolescents. The STS appears to have good test- retest reliability, but a learning effect of about 10%. The association of STS with other measures of physical fitness should be further explored in a larger study and technical standards for its conduct are needed. Y1 - 2021 U6 - https://doi.org/10.1136/bmjopen-2021-049143 SN - 2044-6055 VL - 11 IS - 5 PB - BMJ Publishing Group CY - London ER - TY - JOUR A1 - Jafarnezhadgero, Amir Ali A1 - Fatollahi, Amir A1 - Granacher, Urs T1 - Eight weeks of exercising on sand has positive effects on biomechanics of walking and muscle activities in individuals with pronated feet BT - a randomized double-blinded controlled trial JF - Sports : open access journal N2 - This study aimed to investigate the effects of eight weeks of barefoot running exercise on sand versus control on measures of walking kinetics and muscle activities in individuals with diagnosed pronated feet. Sixty physically active male adults with pronated feet were randomly allocated into an intervention or a waiting control group. The intervention group conducted an 8-weeks progressive barefoot running exercise program on sand (e.g., short sprints) with three weekly sessions. Pre and post intervention, participants walked at a constant speed of 1.3 m/s +/- 5% on a 18 m walkway with a force plate embedded in the middle of the walkway. Results showed significant group-by-time interactions for peak impact vertical and lateral ground reaction forces. Training but not control resulted in significantly lower peak impact vertical and lateral ground reaction forces. Significant group-by-time interactions were observed for vastus lateralis activity during the loading phase. Training-induced increases were found for the vastus lateralis in the intervention but not in the control group. This study revealed that the applied exercise program is a suitable means to absorb ground reaction forces (e.g., lower impact vertical and lateral peaks) and increase activities of selected lower limb muscles (e.g., vastus lateralis) when walking on stable ground. KW - flat foot KW - free moment KW - gait KW - loading rate KW - training Y1 - 2022 U6 - https://doi.org/10.3390/sports10050070 SN - 2075-4663 VL - 10 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Wiesmeier, Isabella K. A1 - Dalin, Daniela A1 - Wehrle, Anja A1 - Granacher, Urs A1 - Muehlbauer, Thomas A1 - Dietterle, Jörg A1 - Weiller, Cornelius A1 - Gollhofer, Albert A1 - Maurer, Christoph T1 - Balance training enhances vestibular function and reduces overactive proprioceptive feedback in elderly JF - Frontiers in aging neuroscience N2 - Objectives: Postural control in elderly people is impaired by degradations of sensory, motor, and higher-level adaptive mechanisms. Here, we characterize the effects of a progressive balance training programon these postural control impairments using a brain network model based on system identification techniques. Methods and Material: We analyzed postural control of 35 healthy elderly subjects and compared findings to data from 35 healthy young volunteers. Eighteen elderly subjects performed a 10 week balance training conducted twice per week. Balance training was carried out in static and dynamic movement states, on support surfaces with different elastic compliances, under different visual conditions and motor tasks. Postural control was characterized by spontaneous sway and postural reactions to pseudorandom anterior-posterior tilts of the support surface. Data were interpreted using a parameter identification procedure based on a brain network model. Conclusion: Balance training reduced overactive proprioceptive feedback and restored vestibular orientation in elderly. Based on the assumption of a linear deterioration of postural control across the life span, the training effect can be extrapolated as a juvenescence of 10 years. This study points to a considerable benefit of a continuous balance training in elderly, even without any sensorimotor deficits. KW - age KW - balance KW - vestibular KW - proprioception KW - training Y1 - 2017 U6 - https://doi.org/10.3389/fnagi.2017.00273 SN - 1663-4365 VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Werfelli, Hanen A1 - Hammami, Raouf A1 - Selmi, Mohamed Amine A1 - Selmi, Walid A1 - Gabrilo, Goran A1 - Clark, Cain C. T. A1 - Duncan, Michael A1 - Sekulic, Damir A1 - Granacher, Urs A1 - Rebai, Haithem T1 - Acute Effects of Different Plyometric and Strength Exercises on Balance Performance in Youth Weightlifters JF - Frontiers in Physiology N2 - Background: High-intensity muscle actions have the potential to temporarily improve the performance which has been denoted as postactivation performance enhancement. Objectives: This study determined the acute effects of different stretch-shortening (fast vs. low) and strength (dynamic vs. isometric) exercises executed during one training session on subsequent balance performance in youth weightlifters. Materials and Methods: Sixteen male and female young weightlifters, aged 11.3±0.6years, performed four strength exercise conditions in randomized order, including dynamic strength (DYN; 3 sets of 3 repetitions of 10 RM) and isometric strength exercises (ISOM; 3 sets of maintaining 3s of 10 RM of back-squat), as well as fast (FSSC; 3 sets of 3 repetitions of 20-cm drop-jumps) and slow (SSSC; 3 sets of 3 hurdle jumps over a 20-cm obstacle) stretch-shortening cycle protocols. Balance performance was tested before and after each of the four exercise conditions in bipedal stance on an unstable surface (i.e., BOSU ball with flat side facing up) using two dependent variables, i.e., center of pressure surface area (CoP SA) and velocity (CoP V). Results: There was a significant effect of time on CoP SA and CoP V [F(1,60)=54.37, d=1.88, p<0.0001; F(1,60)=9.07, d=0.77, p=0.003]. In addition, a statistically significant effect of condition on CoP SA and CoP V [F(3,60)=11.81, d=1.53, p<0.0001; F(3,60)=7.36, d=1.21, p=0.0003] was observed. Statistically significant condition-by-time interactions were found for the balance parameters CoP SA (p<0.003, d=0.54) and CoP V (p<0.002, d=0.70). Specific to contrast analysis, all specified hypotheses were tested and demonstrated that FSSC yielded significantly greater improvements than all other conditions in CoP SA and CoP V [p<0.0001 (d=1.55); p=0.0004 (d=1.19), respectively]. In addition, FSSC yielded significantly greater improvements compared with the two conditions for both balance parameters [p<0.0001 (d=2.03); p<0.0001 (d=1.45)]. Conclusion: Fast stretch-shortening cycle exercises appear to be more effective to improve short-term balance performance in young weightlifters. Due to the importance of balance for overall competitive achievement in weightlifting, it is recommended that young weightlifters implement dynamic plyometric exercises in the fast stretch-shortening cycle during the warm-up to improve their balance performance. KW - postural stability KW - conditioning exercise KW - adolescents KW - performance KW - weightlifting Y1 - 2021 U6 - https://doi.org/10.3389/fphys.2021.716981 SN - 1664-042X VL - 12 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Fernandez-Fernandez, Jaime A1 - Moya-Ramon, Manuel A1 - Santos-Rosa, Francisco Javier A1 - Gantois, Petrus A1 - Nakamura, Fabio Yuzo A1 - Sanz-Rivas, David A1 - Granacher, Urs T1 - Within-session sequence of the tennis serve training in youth elite players JF - International journal of environmental research and public health N2 - The influence of muscular fatigue on tennis serve performance within regular training sessions is unclear. Therefore, the aim of the present study was to examine the within-session sequence of the tennis serve in youth tennis. Twenty-five young male (14.9 +/- 0.9 years) and female (14.5 +/- 0.9 years) players participated in this within-subject crossover study, and they were randomly but sex-matched assigned to different training sequences (serve exercise before tennis training (BTS) or after tennis training (ATS)). Pre- and post-tests included serve velocity performance and accuracy, shoulder strength, and range-of-motion (ROM) performance (internal/external rotation). Results showed that after one week of serve training conducted following the ATS sequence, significant decreases were found in serve performance (e.g., speed and accuracy), with standardized differences ranging from d = 0.29 to 1.13, as well as the shoulder function (strength [d = 0.20 to 1.0] and ROM [d = 0.17 to 0.31]) in both female and male players, compared to the BTS sequence. Based on the present findings, it appears more effective to implement serve training before the regular tennis training in youth players. If applied after training, excessive levels of fatigue may cause shoulder imbalances that could be related to an increased injury risk. KW - athletes KW - athletic performance KW - fatigue KW - fitness KW - shoulder strength KW - range of motion Y1 - 2020 U6 - https://doi.org/10.3390/ijerph18010244 SN - 1660-4601 VL - 18 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Ramirez-Campillo, Rodrigo A1 - Moran, Jason A1 - Oliver, Jonathan L. A1 - Pedley, Jason S. A1 - Lloyd, Rhodri S. A1 - Granacher, Urs T1 - Programming Plyometric-Jump Training in Soccer: A Review JF - Sports N2 - The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different ages and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and Scopus using keywords related to the main topic of this study (e.g., “ballistic” and “plyometric”). According to the PICOS framework, the population for the review was restricted to soccer players, involved in jump or plyometric training. Among 7556 identified studies, 90 were eligible for inclusion. Only 12 studies were found for females. Most studies (n = 52) were conducted with youth male players. Moreover, only 35 studies determined the effectiveness of a given jump training programming factor. Based on the limited available research, it seems that a dose of 7 weeks (1–2 sessions per week), with ~80 jumps (specific of combined types) per session, using near-maximal or maximal intensity, with adequate recovery between repetitions (<15 s), sets (≥30 s) and sessions (≥24–48 h), using progressive overload and taper strategies, using appropriate surfaces (e.g., grass), and applied in a well-rested state, when combined with other training methods, would increase the outcome of effective and safe plyometric-jump training interventions aimed at improving soccer players physical fitness. In conclusion, jump training is an effective and easy-to-administer training approach for youth, adult, male and female soccer players. However, optimal programming for plyometric-jump training in soccer is yet to be determined in future research. KW - human physical conditioning KW - exercise KW - resistance training KW - muscle strength KW - plyometric exercise KW - musculoskeletal and neural physiological phenomena KW - movement KW - sports KW - football KW - youth sport Y1 - 2022 U6 - https://doi.org/10.3390/sports10060094 SN - 2075-4663 VL - 10 SP - 1 EP - 20 PB - MDPI CY - Basel, Schweiz ET - 6 ER - TY - JOUR A1 - Sariati, Dorsaf A1 - Hammami, Raouf A1 - Zouhal, Hassane A1 - Clark, Cain Craig Truman A1 - Nebigh, Ammar A1 - Chtara, Moktar A1 - Chortane, Sabri Gaied A1 - Hackney, Anthony C. A1 - Souissi, Nizar A1 - Granacher, Urs A1 - Ben Ounis, Omar ED - Trecroci, Athos T1 - Improvement of Physical Performance Following a 6 Week Change-of-Direction Training Program in Elite Youth Soccer Players of Different Maturity Levels JF - Frontiers in physiology N2 - Background: Change-of-direction (CoD) is a necessary physical ability of a field sport and may vary in youth players according to their maturation status. Objectives: The aim of this study is: to compare the effectiveness of a 6-week CoD training intervention on dynamic balance (CS-YBT), horizontal jump (5JT), speed (10 and 30-m linear sprint times), CoD with (15 m-CoD + B) and without (15 m-CoD) the ball, in youth male soccer players at different levels of maturity [pre- and post-peak height velocity (PHV)]. Materials and Methods: Thirty elite male youth soccer players aged 10–17 years from the Tunisian first division participated in this study. The players were divided into pre- (G1, n = 15) and post-PHV (G2, n = 15) groups. Both groups completed a similar 6-week training program with two sessions per week of four CoD exercises. All players completed the following tests before and after intervention: CS-YBT; 5 JT; 10, 30, and 15 m-CoD; and 15 m-CoD + B, and data were analyzed using ANCOVA. Results: All 30 players completed the study according to the study design and methodology. Adherence rate was 100% across all groups, and no training or test-related injuries were reported. Pre-PHV and post-PHV groups showed significant amelioration post-intervention for all dependent variables (after test > before test; p < 0.01, d = 0.09–1.51). ANOVA revealed a significant group × time interaction only for CS-YBT (F = 4.45; p < 0.04; η2 = 0.14), 5JT (F = 6.39; p < 0.02; η2 = 0.18), and 15 m-CoD (F = 7.88; p < 0.01; η2 = 0.22). CS-YBT, 5JT, and 15 m-CoD improved significantly in the post-PHV group (+ 4.56%, effect size = 1.51; + 4.51%, effect size = 1.05; and -3.08%, effect size = 0.51, respectively), more than the pre-PHV group (+ 2.77%, effect size = 0.85; + 2.91%, effect size = 0.54; and -1.56%, effect size = 0.20, respectively). Conclusion: The CoD training program improved balance, horizontal jump, and CoD without the ball in male preadolescent and adolescent soccer players, and this improvement was greater in the post-PHV players. The maturity status of the athletes should be considered when programming CoD training for soccer players. KW - youth soccer KW - peak height velocity KW - change of direction speed KW - training adaptation KW - football Y1 - 2021 U6 - https://doi.org/10.3389/fphys.2021.668437 SN - 1664-042X VL - 12 SP - 1 EP - 8 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Sandau, Ingo A1 - Granacher, Urs T1 - Effects of the barbell load on the acceleration phase during the snatch in elite Olympic weightlifting JF - Sports N2 - The load-depended loss of vertical barbell velocity at the end of the acceleration phase limits the maximum weight that can be lifted. Thus, the purpose of this study was to analyze how increased barbell loads affect the vertical barbell velocity in the sub-phases of the acceleration phase during the snatch. It was hypothesized that the load-dependent velocity loss at the end of the acceleration phase is primarily associated with a velocity loss during the 1st pull. For this purpose, 14 male elite weightlifters lifted seven load-stages from 70-100% of their personal best in the snatch. The load-velocity relationship was calculated using linear regression analysis to determine the velocity loss at 1st pull, transition, and 2nd pull. A group mean data contrast analysis revealed the highest load-dependent velocity loss for the 1st pull (t = 1.85, p = 0.044, g = 0.49 [-0.05, 1.04]) which confirmed our study hypothesis. In contrast to the group mean data, the individual athlete showed a unique response to increased loads during the acceleration sub-phases of the snatch. With the proposed method, individualized training recommendations on exercise selection and loading schemes can be derived to specifically improve the sub-phases of the snatch acceleration phase. Furthermore, the results highlight the importance of single-subject assessment when working with elite athletes in Olympic weightlifting. KW - biomechanics KW - barbell velocity KW - performance KW - training KW - load-velocity KW - relationship Y1 - 2020 U6 - https://doi.org/10.3390/sports8050059 SN - 2075-4663 VL - 8 IS - 5 PB - MDPI CY - Basel ER -