Pivoting neuromuscular control and proprioception in females and males.

PURPOSE: Noncontact ACL injuries occur most commonly in pivoting sports and are much more frequent in females than in males. However, information on sex differences in proprioceptive acuity under weight-bearing and leg neuromuscular control in pivoting is scarce. The objective of this study was to investigate sex differences in pivoting neuromuscular control during strenuous stepping tasks and proprioceptive acuity under weight-bearing. METHODS: 21 male and 22 female subjects were recruited to evaluate pivoting proprioceptive acuity under weight-bearing, and pivoting neuromuscular control (in terms of leg pivoting instability, stiffness, maximum internal and external pivoting angles, and entropy of time-to-peak EMG in lower limb muscles) during strenuous stepping tasks performed on a novel offaxis elliptical trainer. RESULTS: Compared to males, females had significantly lower proprioceptive acuity under weight-bearing in both internal and external pivoting directions, higher pivoting instability, larger maximum internal pivoting angle, lower leg pivoting stiffness, and higher entropy of time-to-peak EMG in the gastrocnemius muscles during strenuous stepping tasks with internal and external pivoting perturbations. CONCLUSIONS: Results of this study may help us better understand factors contributing to ACL injuries in females and males, develop training strategies to improve pivoting neuromuscular control and proprioceptive acuity, and potentially reduce ACL and lower-limb musculoskeletal injuries.

Effects of pivoting neuromuscular training on pivoting control and proprioception.

PURPOSE: Pivoting neuromuscular control and proprioceptive acuity may play an important role in anterior cruciate ligament injuries. The goal of this study was to investigate whether pivoting off-axis intensity adjustable neuromuscular control training (POINT) could improve pivoting neuromuscular control, proprioceptive acuity, and functional performance. METHODS: Among 41 subjects, 21 subjects participated in 18 sessions of POINT (three sessions per week for 6 wk), and 20 subjects served as controls who did their regular workout. Both groups received pre-, mid-, and postintervention evaluations. Propensity score analysis with multivariable regression adjustment was used to investigate the effect of training on pivoting neuromuscular control (pivoting instability, leg pivoting stiffness, maximum internal, and external pivoting angles), proprioceptive acuity, and functional performance in both groups. RESULTS: Compared with the control group, the training group significantly improved pivoting neuromuscular control as reduced pivoting instability, reduced maximum internal and external pivoting angles, increased leg pivoting stiffness, and decreased entropy of time to peak EMG in the gluteus maximus and lateral gastrocnemius under pivoting perturbations. Furthermore, the training group enhanced weight-bearing proprioceptive acuity and improved the single leg hop distance. CONCLUSION: Improvement of pivoting neuromuscular control in functional weight-bearing activities and task performances after POINT may help develop lower limb injury prevention and rehabilitation methods to reduce anterior cruciate ligament and other musculoskeletal injuries associated with pivoting sports.

Gender differences in offaxis neuromuscular control during stepping under a slippery condition.

PURPOSE: Females are at greater risks of musculoskeletal injuries than are males, which may be related to decreased neuromuscular control in axial and/or frontal planes, offaxis neuromuscular control. The objective of this study was to investigate gender differences in offaxis neuromuscular control during stepping under a slippery condition. METHODS: Forty-three healthy subjects (21 males and 22 females) performed different stepping tasks under a slippery condition, namely, free pivoting task (FPT) to control axial plane pivoting, free sliding task (FST) to control frontal plane sliding, and free pivoting and sliding task (FPST) to control axial pivoting, and frontal sliding on a custom-made offaxis elliptical trainer. RESULTS: Compared to males, females showed significantly higher pivoting instability, higher max internal and external pivoting angles, higher mean max medial and lateral sliding distance, and higher entropy of time to peak EMG in the medial and lateral gastrocnemius muscles during the FPST and higher entropy of time to peak EMG in the lateral gastrocnemius muscle during the FPT and FST. CONCLUSIONS: The findings may help us understand potential injury risk factors associated with gender differences, and provide a basis for developing targeted neuromuscular training to improve offaxis neuromuscular control, and reduce musculoskeletal injuries associated with excessive offaxis loadings.

Offaxis neuromuscular training of knee injuries using an offaxis robotic elliptical trainer.

The goal of this study was to use an offaxis robotic elliptical trainer to improve off-axis neuromuscular control in people with knee injuries. Thirteen individuals with knee injuries participated in the study. Among them, 8 individuals participated in 18 sessions of pivoting offaxis intensity-adjustable neuromuscular control training (POINT) (3 sessions/week for 6 weeks including 3 evaluation sessions) to improve offaxis neuromuscular control, specifically dynamic lower limb stability in pivoting. 5 individuals served as controls who only participated in the three evaluations. Following POINT patients in the training group reduced pivoting instability (p=0.024), while the control group did not (p=0.118). Individuals in the training group were able to hop farther in a single leg hop for distance task, take shorter in 12 m hop time for time task, and reported reduced knee pain. The results suggest that subject-specific POINT utilizing the novel robotic elliptical trainer can be implemented as a rehabilitation protocol for patients with knee injuries to improve their lower limb functions and reduce knee symptoms.

Improvement in off-axis neuromuscular control through pivoting elliptical training: Implication for knee injury prevention.

The goal of this study was to investigate the efficacy of off-axis neuromuscular control training using a pivoting elliptical machine. Although knee motion is mainly in flexion/extension, injuries to the knee are usually associated with excessive off-axis movement (tibial axial rotation and valgus/varus). A pivoting elliptical training system was developed to improve neuromuscular control about the off-axes. Six week training was conducted in nine healthy individuals and seven healthy individuals served as control and only participated in evaluation sessions. Our results showed that following the pivoting elliptical training, individuals were able to reduce pivoting instability across different phases of the elliptical cycle (p〈0.01) and also mediolateral instability at mid and terminal swing phase (p〈0.05). A trend of reduced response time and phase dependent changes in EMG patterns were also observed. The results showed that the pivoting elliptical training is effective to improve off-axis neuromuscular control in healthy individuals and such training protocol can potentially be implemented to prevent knee injury.

Training for knee injury prevention using a pivoting elliptical machine.

Anterior cruciate ligament (ACL) is the most commonly injured knee ligament in sports-related activities, especially in pivoting sports. In general, knee joint movements about the off-axes are much more limited and musculoskeletal injuries are usually associated with excessive loading/movement about the off-axes. The purposes of this project were to develop an injury prevention program including a pivoting elliptical exercise machine to address the specific ACL injury mechanisms, especially in women. ACL injury prevention training was carried out to target the specific injury mechanisms associated with tibial rotation. The pivoting elliptical training improved the off-axis neuromuscular control considerably. Training-induced neuromuscular changes in tibial rotation were assessed with multiple outcome measures.