The effect of different hip rotation angles on electromyography activity of the quadriceps muscle during closed kinetic chain tasks in healthy females

Muscle modes of the equestrian rider at walk, rising trot and canter

Equestrian sports have been a source of numerous studies throughout the past two decades, however, few scientists have focused on the biomechanical effects, including muscle activation, that the horse has on the rider. Because equitation is a sport of two (the horse-human dyad), we believe there is a need to fill in the knowledge gap in human biomechanics during riding. To investigate the differences between novice and advanced riders at a neuromuscular level we characterized the motor output of a set of riders’ key muscles during horse riding. Six recreational riders (24 ± 7 years) and nine professional riders (31 ± 5 years) from the Spanish Classical School of Riding (Lipica) volunteered to take part in this study. Riders’ upper body, core and lower limb muscles were monitored and synchronized with inertial data from the left horse’s leg at walk, rising trot and canter. We used principal component analysis to extract muscle modes. Three modes were identified in the advanced group whereas five modes were identified in the novice group. From the novice group, one mode united dorsal and ventral muscles of the body (reciprocal mode). Advanced riders showed higher core muscles engagement and better intermuscular coordination. We concluded that advanced horse riding is characterized by an ability to activate muscles contralaterally but not reciprocally (dorsal-ventral contraction). In addition, activating each muscle independently with different levels of activation, and the ability to quickly decrease overall muscle activity is distinctive of advanced riders.

Biomechanical Evaluation of Preoperative Rehabilitation in Patients of Anterior Cruciate Ligament Injury

Objectives

To investigate the biomechanical characteristics of patients with anterior cruciate ligament (ACL) injury by gait analysis, surface electromyography (SEMG), and proprioception test, and provide rehabilitation suggestions according to the results.

Methods

In this retrospective cohort study, 90 adults with unilateral ACL injury, ranging in age from 19 to 45 years (66 men and 24 women, average age: 30.03 ± 7.91) were recruited for this study form May 2018 to July 2019. They were divided into three groups according to the time after the injury: group A (3‐week to 1.5‐month), group B (1.5‐month to 1 year), and group C (more than 1 year). The SEMG signals were collected from the bilateral rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) and the root mean square (RMS) were used to assess muscular activity. SEMG were used to analyze muscles function, gait analysis was used to evaluate the walking stability, balance and location assessment were used to analyze the proprioception.

Results

Through the comparison between bilateral limbs, all muscles strength shown decreased (RF: 239.94 ± 129.70 vs 364.81 ± 148.98, P = 0.001; VM: 298.88 ± 175.41 vs 515.79 ± 272.49, P = 0.001; VL:389.54 ± 157.97 vs 594.28 ± 220.31, P < 0.001) and the division of proprioception became larger (tandem position: 7.79 ± 1.57 vs 6.33 ± 1.49, P = 0.001; stance with one foot: 8.13 ± 0.84 vs 7.1 ± 0.57, P = 0.003; variance of 30°: 6.96 ± 3.15 vs 4.45 ± 1.67, P = 0.03; variance of 60°: 4.64 ± 3.38 vs 2.75 ± 1.98, P = 0.044) in the injured side when compared to the non‐injured and 26 gait parameters were shown difference in group A. In group B, the muscle strength of VL shown decreased (VL: 381.23 ± 142.07 vs 603.9 ± 192.72, P < 0.001) and the division of location of 30° became larger (7.62 ± 4.98 vs 4.33 ± 3.24, P = 0.028) in the injured side when compared to the non‐injured side and there were eight gait parameters that showed differences. In group C, the muscle strength and proprioception showed no differences and only 16 gait parameters showed differences between the bilateral limbs.

Conclusion

The results proved the deterioration of proprioception in 30° of injured side will not recover and non‐injury side and will become worse after 1 year from the injury; among the VL, VM, and RF, the recovery rate of VL is the slowest and bilateral straight leg raising (SLR) (30°) is the best way to train it; the gait stability will be worse after 1 year from the injury. Therefore, we suggest that the training for proprioception in 30° and VL are important for the rehabilitation, and the ACL reconstruction should be performed within 1 year.