Journal of Electromyography and Kinesiology, Oct 15, 2011
The aims of this study were:(i) to present the kinematic and electromyographic patterns of the ch... more The aims of this study were:(i) to present the kinematic and electromyographic patterns of the choku-zuki punch performed by 18 experienced karatekas from the Portuguese team, and (ii) to compare it with the execution of 19 participants without any karate experience. The kinematic and electromyographic data were collected from the arm and forearm during the execution of the specific punch. A two-way analysis of variance (ANOVA) was used with significant level set at p⩽ 0.05.
The purpose of this study was to assess kinematic and kinetic differences between three tasks (dr... more The purpose of this study was to assess kinematic and kinetic differences between three tasks (drop-jump, sidestep cutting, and pivot tasks) commonly used to evaluate anterior cruciate ligament risk factors. Nineteen female collegiate soccer athletes from a Division I institution participated in this study. Participants performed a drop-jump task, and two unanticipated tasks, sidestep cutting and pivot. Repeated-measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between tasks. The pivot task had lower knee flexion (−41.2 ± 8.8°) and a higher valgus angle (−7.6 ± 10.1°) than the sidestep (−53.9 ± 9.4° and −2.9 ± 10.0°, respectively) at maximum vertical ground reaction force. The pivot task (0.8 ± 0.3 multiples of body weight) had higher peak posterior ground reaction force than the drop-jump (0.3 ± 0.06 multiples of body weight) and sidestep cutting (0.3 ± 0.1 multiples of body weight), as well as higher internal varus moments (0.72 ± 0.3 N · m/kg · m) than the drop-jump (0.14 ± 0.07 N · m/kg · m) and sidestep (0.17 ± 0.5 N · m/kg · m) at peak stance. During the pivot task, the athletes presented a more erect posture and adopted strategies that may place higher loads on the knee joint and increase the strain on the anterior cruciate ligament.
The purpose of this study was to evaluate the effects of a functional agility fatigue protocol on... more The purpose of this study was to evaluate the effects of a functional agility fatigue protocol on lower extremity biomechanics between two unanticipated tasks (stop-jump and sidestep). The subjects consisted of fifteen female collegiate soccer athletes (19±0.7 years, 1.67±0.1 m, 61.7±8 kg) free of lower extremity injury. Participants performed five trials of stop-jump and sidestep tasks. A functional short-term agility protocol was performed, and immediately following participants repeated the unanticipated running tasks. Lower extremity kinematic and kinetic values were obtained pre and post fatigue. Repeated measures analyses of variance were conducted for each dependent variable with an alpha level set at 0.05. Knee position post-fatigue had increased knee internal rotation (11.4±7.5° vs. 7.9±6.5° p=0.011) than pre-fatigue, and a decreased knee flexion angle (–36.6±6.2° vs. −40.0±6.3°, p=0.003), as well as hip position post-fatigue had decreased hip flexion angle (35.5±8.7° vs. 43.2±9.5°, p=0.002). A quick functional fatigue protocol altered lower extremity mechanics of Division I collegiate soccer athletes during landing tasks. Proper mechanics should be emphasized from the beginning of practice/game to aid in potentially minimizing the effects of fatigue in lower extremity mechanics.
The improvement of ecological validity of laboratory research studies has recently come to the fo... more The improvement of ecological validity of laboratory research studies has recently come to the forefront of technology with virtual reality scenarios. The purpose of this study was to assess differences between unanticipated and anticipated lower extremity biomechanics while performing a sidestep cutting task. A visualization software was developed for this purpose, which would recreate a soccer game situation for use in a laboratory setting. Thirteen participants volunteered for this study. Lower extremity biomechanical data were collected with a VICON motion analysis system and two force plates, under anticipated and unanticipated conditions while performing a sidestep cutting task. Paired t-tests were conducted to assess possible differences between conditions. Alpha level was set a priori at 0.05. We found an increased knee adduction angle (unanticipated: -7.2 ± 5.3°; anticipated: -4.0 ± 5.3°), and knee internal rotation (unanticipated: 8.1 ± 4.7°; anticipated: 5.2 ± 6.5°) when performing the unanticipated condition (p < 0.05). The methodological approaches for studies investigating the factors possibly associated with ACL injury may need to take into account the laboratory environment and how the task(s) are presented to the participants.
Journal of Electromyography and Kinesiology, Oct 15, 2011
The aims of this study were:(i) to present the kinematic and electromyographic patterns of the ch... more The aims of this study were:(i) to present the kinematic and electromyographic patterns of the choku-zuki punch performed by 18 experienced karatekas from the Portuguese team, and (ii) to compare it with the execution of 19 participants without any karate experience. The kinematic and electromyographic data were collected from the arm and forearm during the execution of the specific punch. A two-way analysis of variance (ANOVA) was used with significant level set at p⩽ 0.05.
The purpose of this study was to assess kinematic and kinetic differences between three tasks (dr... more The purpose of this study was to assess kinematic and kinetic differences between three tasks (drop-jump, sidestep cutting, and pivot tasks) commonly used to evaluate anterior cruciate ligament risk factors. Nineteen female collegiate soccer athletes from a Division I institution participated in this study. Participants performed a drop-jump task, and two unanticipated tasks, sidestep cutting and pivot. Repeated-measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between tasks. The pivot task had lower knee flexion (−41.2 ± 8.8°) and a higher valgus angle (−7.6 ± 10.1°) than the sidestep (−53.9 ± 9.4° and −2.9 ± 10.0°, respectively) at maximum vertical ground reaction force. The pivot task (0.8 ± 0.3 multiples of body weight) had higher peak posterior ground reaction force than the drop-jump (0.3 ± 0.06 multiples of body weight) and sidestep cutting (0.3 ± 0.1 multiples of body weight), as well as higher internal varus moments (0.72 ± 0.3 N · m/kg · m) than the drop-jump (0.14 ± 0.07 N · m/kg · m) and sidestep (0.17 ± 0.5 N · m/kg · m) at peak stance. During the pivot task, the athletes presented a more erect posture and adopted strategies that may place higher loads on the knee joint and increase the strain on the anterior cruciate ligament.
The purpose of this study was to evaluate the effects of a functional agility fatigue protocol on... more The purpose of this study was to evaluate the effects of a functional agility fatigue protocol on lower extremity biomechanics between two unanticipated tasks (stop-jump and sidestep). The subjects consisted of fifteen female collegiate soccer athletes (19±0.7 years, 1.67±0.1 m, 61.7±8 kg) free of lower extremity injury. Participants performed five trials of stop-jump and sidestep tasks. A functional short-term agility protocol was performed, and immediately following participants repeated the unanticipated running tasks. Lower extremity kinematic and kinetic values were obtained pre and post fatigue. Repeated measures analyses of variance were conducted for each dependent variable with an alpha level set at 0.05. Knee position post-fatigue had increased knee internal rotation (11.4±7.5° vs. 7.9±6.5° p=0.011) than pre-fatigue, and a decreased knee flexion angle (–36.6±6.2° vs. −40.0±6.3°, p=0.003), as well as hip position post-fatigue had decreased hip flexion angle (35.5±8.7° vs. 43.2±9.5°, p=0.002). A quick functional fatigue protocol altered lower extremity mechanics of Division I collegiate soccer athletes during landing tasks. Proper mechanics should be emphasized from the beginning of practice/game to aid in potentially minimizing the effects of fatigue in lower extremity mechanics.
The improvement of ecological validity of laboratory research studies has recently come to the fo... more The improvement of ecological validity of laboratory research studies has recently come to the forefront of technology with virtual reality scenarios. The purpose of this study was to assess differences between unanticipated and anticipated lower extremity biomechanics while performing a sidestep cutting task. A visualization software was developed for this purpose, which would recreate a soccer game situation for use in a laboratory setting. Thirteen participants volunteered for this study. Lower extremity biomechanical data were collected with a VICON motion analysis system and two force plates, under anticipated and unanticipated conditions while performing a sidestep cutting task. Paired t-tests were conducted to assess possible differences between conditions. Alpha level was set a priori at 0.05. We found an increased knee adduction angle (unanticipated: -7.2 ± 5.3°; anticipated: -4.0 ± 5.3°), and knee internal rotation (unanticipated: 8.1 ± 4.7°; anticipated: 5.2 ± 6.5°) when performing the unanticipated condition (p < 0.05). The methodological approaches for studies investigating the factors possibly associated with ACL injury may need to take into account the laboratory environment and how the task(s) are presented to the participants.
Uploads
Papers by Nelson Cortes