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26 The aim of this study was to perform an electromyography comparison of three commonly 27 used ... more 26 The aim of this study was to perform an electromyography comparison of three commonly 27 used lower limb injury prevention exercises: a single-leg squat on a bench (SLSB), a double-leg 28 squat (DLS) and a double-leg squat on a BOSU® balance trainer (DLSB). After determining the 29 maximum isometric voluntary contraction of the hamstring and quadriceps, eight female athletes 30 performed 3 repetitions of each exercise, while electromyography activity of the biceps femoris 31 (BF), semitendinosus (ST), vastus lateralis (VL) and vastus medialis (VM) was monitored. 32 Comparisons between exercises revealed higher activation in BF (descending phase: p = 0.016, d = 33 1.36; ascending phase: p = 0.046, d = 1.11), ST (descending phase: p = 0.04, d = 1.87; ascending 34 phase: p = 0.04, d = 1.87), VL (ascending phase: p = 0.04, d = 1.17) and VM (descending phase: p 35 = 0.05, d = 1.11; ascending phase: p = 0.021, d = 1.133) muscles for the SLSB compared to the 36 DLSQ. Furthermore, higher...

Hamstring and anterior cruciate ligament injuries are, respectively, the most prevalent and serio... more Hamstring and anterior cruciate ligament injuries are, respectively, the most prevalent and serious non-contact occurring injuries in team sports. Several biomechanical and neuromuscular risk factors have been suggested to be associated with these injuries. Consequently, preventative programmes including different exercise modality have been proposed to modify the injury risk factors. However, there is still a lack of uniform criteria regarding the design of an ideal protocol for effective protection against the two aforementioned injuries in team sport athletes. The preliminary study (study 1) was carried out to evaluate the effect of two different preventative programmes on hamstring strength and torque angle relationship. The results revealed that although both programmes increased hamstring strength, the effect of interventions on knee flexors torque-angle relationship was significantly different. Therefore, a systematic review of literature (study 2) was conducted to clarify th...

Journal of Human Kinetics

The aim of this study was to perform an electromyography comparison of three commonly used lower ... more The aim of this study was to perform an electromyography comparison of three commonly used lower limb injury prevention exercises: a single-leg squat on a bench (SLSB), a double-leg squat (DLS) and a double-leg squat on a BOSU® balance trainer (DLSB). After determining the maximum isometric voluntary contraction of the hamstring and quadriceps, eight female athletes performed 3 repetitions of each exercise, while electromyography activity of the biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL) and vastus medialis (VM) was monitored. Comparisons between exercises revealed higher activation in BF (descending phase: p = 0.016, d = 1.36; ascending phase: p = 0.046, d = 1.11), ST (descending phase: p = 0.04, d = 1.87; ascending phase: p = 0.04, d = 1.87), VL (ascending phase: p = 0.04, d = 1.17) and VM (descending phase: p = 0.05, d = 1.11; ascending phase: p = 0.021, d = 1.133) muscles for the SLSB compared to the DLSQ. Furthermore, higher muscular activation of the ST (a...

Journal of Strength and Conditioning Research

The present study compares the effect of an isoinertial flywheel technology vs. a traditional gra... more The present study compares the effect of an isoinertial flywheel technology vs. a traditional gravity-dependent exercise protocol on modifiable factors associated with the incidence of hamstring strain (HAM) and anterior cruciate ligament (ACL) injuries. Furthermore, the effect on repeated sprint ability was also considered. Eighteen recreationally trained volleyball players completed one of the following 6-week protocols: (i) flywheel (FY) included three exercises using a yo-yo isoinertial-squat machine and three exercising with a versa pulley isoinertial device (ii) gravity dependent (GT) involved 6 similar exercises with no external resistance (participants' body weight). Both programs consisted in 2 sessions/week performing 2 sets of 8 repetitions with 2 min rest. Outcomes included a 10 sec tuck jump assessment (TJA), landing knee valgus score, hamstring and quadriceps concentric and eccentric isokinetic 60°.s-1 peak torque, optimal peak torque localization, conventional and functional hamstring-toquadriceps ratio and 10 m repeated shuttle sprint ability test (RSSA). FY improved TJA (-2, IQR =-3 to-1) and valgus (-1, IQR =-1 to 0) scores, hamstring eccentric (20.37, 95% CI = 9.27, 31.47 Nm) and concentric (17.87, 95% CI = 0.40, 35.34 Nm) peak torque, as well as the RSSA (-0.28, 95% CI =-0.45,-0.10 sec), while GT only improved hamstring eccentric peak torque (21.41, 95% CI = 9.00, 33.82 Nm). A 6-week protocol using flywheel technology seems to elicit better positive adaptations to protect athletes from HAM and ACL injuries and to enhance RSSA performance compared to exercising with no external resistance other than athletes' body weight.

PLOS ONE, 2016

Background Hamstring strain and anterior cruciate ligament injuries are, respectively, the most p... more Background Hamstring strain and anterior cruciate ligament injuries are, respectively, the most prevalent and serious non-contact occurring injuries in team sports. Specific biomechanical and neuromuscular variables have been used to estimate the risk of incurring a non-contact injury in athletes. Objective The aim of this study was to systematically review the evidences for the effectiveness of injury prevention protocols to modify biomechanical and neuromuscular anterior cruciate and/or hamstring injuries associated risk factors in uninjured team sport athletes. Data Sources PubMed, Science Direct, Web of Science, Cochrane Libraries, U.S. National Institutes of Health clinicaltrials.gov, Sport Discuss and Google Scholar databases were searched for relevant journal articles published until March 2015. A manual review of relevant articles, authors, and journals, including bibliographies was performed from identified articles. Main Results Nineteen studies were included in this review. Four assessment categories: i) landing, ii) side cutting, iii) stop-jump, and iv) muscle strength outcomes, were used to analyze the effectiveness of the preventive protocols. Eight studies using multifaceted interventions supported by video and/or technical feedback showed improvement in landing and/or stopjump biomechanics, while no effects were observed on side-cutting maneuver.

Research in Sports Medicine, 2015

The effects of two different 6-week lower body injury prevention programmes on knee muscle torque... more The effects of two different 6-week lower body injury prevention programmes on knee muscle torque-angle relationship were examined in soccer players. Thirty-two men were randomly assigned to three groups: hamstring-eccentric (ECC) (n = 11), unstable-squatting (UNS) (n = 11), and control (n = 10). Intervention groups performed three training sessions per week using only three ECC or UNS exercises, respectively. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100°, pre- and post-intervention. Peak torque increased at 35° (P = 0.034, Cohen's d = 0.67) and 45° (P = 0.004, Cohen's d = 0.96) in the ECC group, and at 60° (P = 0.024, Cohen's d = 1.16), 80° (P = 0.018, Cohen's d = 1.21), and 90° (P = 0.001, Cohen's d = 1.38) in the UNS group. As these specific modifications might respectively and differentially protect athletes against hamstring and knee-joint injuries, the integration of both types of exercises should be considered when designing injury prevention programmes for soccer players.

Journal of Human Kinetics

The aim of this study was to perform an electromyographic and kinetic comparison of two commonly ... more The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of ...

26 The aim of this study was to perform an electromyography comparison of three commonly 27 used ... more 26 The aim of this study was to perform an electromyography comparison of three commonly 27 used lower limb injury prevention exercises: a single-leg squat on a bench (SLSB), a double-leg 28 squat (DLS) and a double-leg squat on a BOSU® balance trainer (DLSB). After determining the 29 maximum isometric voluntary contraction of the hamstring and quadriceps, eight female athletes 30 performed 3 repetitions of each exercise, while electromyography activity of the biceps femoris 31 (BF), semitendinosus (ST), vastus lateralis (VL) and vastus medialis (VM) was monitored. 32 Comparisons between exercises revealed higher activation in BF (descending phase: p = 0.016, d = 33 1.36; ascending phase: p = 0.046, d = 1.11), ST (descending phase: p = 0.04, d = 1.87; ascending 34 phase: p = 0.04, d = 1.87), VL (ascending phase: p = 0.04, d = 1.17) and VM (descending phase: p 35 = 0.05, d = 1.11; ascending phase: p = 0.021, d = 1.133) muscles for the SLSB compared to the 36 DLSQ. Furthermore, higher...

Hamstring and anterior cruciate ligament injuries are, respectively, the most prevalent and serio... more Hamstring and anterior cruciate ligament injuries are, respectively, the most prevalent and serious non-contact occurring injuries in team sports. Several biomechanical and neuromuscular risk factors have been suggested to be associated with these injuries. Consequently, preventative programmes including different exercise modality have been proposed to modify the injury risk factors. However, there is still a lack of uniform criteria regarding the design of an ideal protocol for effective protection against the two aforementioned injuries in team sport athletes. The preliminary study (study 1) was carried out to evaluate the effect of two different preventative programmes on hamstring strength and torque angle relationship. The results revealed that although both programmes increased hamstring strength, the effect of interventions on knee flexors torque-angle relationship was significantly different. Therefore, a systematic review of literature (study 2) was conducted to clarify th...

Journal of Human Kinetics

The aim of this study was to perform an electromyography comparison of three commonly used lower ... more The aim of this study was to perform an electromyography comparison of three commonly used lower limb injury prevention exercises: a single-leg squat on a bench (SLSB), a double-leg squat (DLS) and a double-leg squat on a BOSU® balance trainer (DLSB). After determining the maximum isometric voluntary contraction of the hamstring and quadriceps, eight female athletes performed 3 repetitions of each exercise, while electromyography activity of the biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL) and vastus medialis (VM) was monitored. Comparisons between exercises revealed higher activation in BF (descending phase: p = 0.016, d = 1.36; ascending phase: p = 0.046, d = 1.11), ST (descending phase: p = 0.04, d = 1.87; ascending phase: p = 0.04, d = 1.87), VL (ascending phase: p = 0.04, d = 1.17) and VM (descending phase: p = 0.05, d = 1.11; ascending phase: p = 0.021, d = 1.133) muscles for the SLSB compared to the DLSQ. Furthermore, higher muscular activation of the ST (a...

Journal of Strength and Conditioning Research

The present study compares the effect of an isoinertial flywheel technology vs. a traditional gra... more The present study compares the effect of an isoinertial flywheel technology vs. a traditional gravity-dependent exercise protocol on modifiable factors associated with the incidence of hamstring strain (HAM) and anterior cruciate ligament (ACL) injuries. Furthermore, the effect on repeated sprint ability was also considered. Eighteen recreationally trained volleyball players completed one of the following 6-week protocols: (i) flywheel (FY) included three exercises using a yo-yo isoinertial-squat machine and three exercising with a versa pulley isoinertial device (ii) gravity dependent (GT) involved 6 similar exercises with no external resistance (participants' body weight). Both programs consisted in 2 sessions/week performing 2 sets of 8 repetitions with 2 min rest. Outcomes included a 10 sec tuck jump assessment (TJA), landing knee valgus score, hamstring and quadriceps concentric and eccentric isokinetic 60°.s-1 peak torque, optimal peak torque localization, conventional and functional hamstring-toquadriceps ratio and 10 m repeated shuttle sprint ability test (RSSA). FY improved TJA (-2, IQR =-3 to-1) and valgus (-1, IQR =-1 to 0) scores, hamstring eccentric (20.37, 95% CI = 9.27, 31.47 Nm) and concentric (17.87, 95% CI = 0.40, 35.34 Nm) peak torque, as well as the RSSA (-0.28, 95% CI =-0.45,-0.10 sec), while GT only improved hamstring eccentric peak torque (21.41, 95% CI = 9.00, 33.82 Nm). A 6-week protocol using flywheel technology seems to elicit better positive adaptations to protect athletes from HAM and ACL injuries and to enhance RSSA performance compared to exercising with no external resistance other than athletes' body weight.

PLOS ONE, 2016

Background Hamstring strain and anterior cruciate ligament injuries are, respectively, the most p... more Background Hamstring strain and anterior cruciate ligament injuries are, respectively, the most prevalent and serious non-contact occurring injuries in team sports. Specific biomechanical and neuromuscular variables have been used to estimate the risk of incurring a non-contact injury in athletes. Objective The aim of this study was to systematically review the evidences for the effectiveness of injury prevention protocols to modify biomechanical and neuromuscular anterior cruciate and/or hamstring injuries associated risk factors in uninjured team sport athletes. Data Sources PubMed, Science Direct, Web of Science, Cochrane Libraries, U.S. National Institutes of Health clinicaltrials.gov, Sport Discuss and Google Scholar databases were searched for relevant journal articles published until March 2015. A manual review of relevant articles, authors, and journals, including bibliographies was performed from identified articles. Main Results Nineteen studies were included in this review. Four assessment categories: i) landing, ii) side cutting, iii) stop-jump, and iv) muscle strength outcomes, were used to analyze the effectiveness of the preventive protocols. Eight studies using multifaceted interventions supported by video and/or technical feedback showed improvement in landing and/or stopjump biomechanics, while no effects were observed on side-cutting maneuver.

Research in Sports Medicine, 2015

The effects of two different 6-week lower body injury prevention programmes on knee muscle torque... more The effects of two different 6-week lower body injury prevention programmes on knee muscle torque-angle relationship were examined in soccer players. Thirty-two men were randomly assigned to three groups: hamstring-eccentric (ECC) (n = 11), unstable-squatting (UNS) (n = 11), and control (n = 10). Intervention groups performed three training sessions per week using only three ECC or UNS exercises, respectively. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100°, pre- and post-intervention. Peak torque increased at 35° (P = 0.034, Cohen's d = 0.67) and 45° (P = 0.004, Cohen's d = 0.96) in the ECC group, and at 60° (P = 0.024, Cohen's d = 1.16), 80° (P = 0.018, Cohen's d = 1.21), and 90° (P = 0.001, Cohen's d = 1.38) in the UNS group. As these specific modifications might respectively and differentially protect athletes against hamstring and knee-joint injuries, the integration of both types of exercises should be considered when designing injury prevention programmes for soccer players.

Journal of Human Kinetics

The aim of this study was to perform an electromyographic and kinetic comparison of two commonly ... more The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of ...