Changes in the Trend of Walking Motor Control in Athletes with Anterior Cruciate Ligament Deficiency in Response to Progressive Perturbation Trainings

Research Article

Austin Sports Med. 2021; 6(1): 1045.

Changes in the Trend of Walking Motor Control in Athletes with Anterior Cruciate Ligament Deficiency in Response to Progressive Perturbation Trainings

Jomhouri S1*, Talebian S2, Vaez-Mousavi M3, Hatef B4 and Sadjadi-Hazaveh SH5

1Department of Motor Behavior, Central Branch of Islamic Azad University, Iran

2Department of Motor Control, Tehran University of Medical Sciences (TUMS), Iran

3Department of Knowledge and Cognitive Intelligence, Imam Hossein University, Iran

4Neuroscience Research Center, Baqiyatallah University of Medical Science, Tehran, Iran

5Department of Sport Management, Central Branch of Islamic Azad University, Iran

*Corresponding author: Jomhouri S, Department of Motor Behavior, Faculty of Physical Education and Sport Sciences, Central Branch of Islamic Azad University, Velayat Complex, Shahid Sohani St, Iran

Received: February 13, 2021; Accepted: March 16, 2021; Published: March 23, 2021


Background and Purpose: The beliefs are that sudden and unpredictable balance disturbance by instruments that cause mechanical perturbations can affect individuals with Anterior Cruciate Ligament Deficiency (ACLD) to reach faster and more effective recovery of knee dynamic stabilization strategies to return successfully pre-injury levels. The aim of this study was to investigate the effect of mechanical perturbation training and standard training in the process of changes in motor control during walking task in coper ACLD individuals.

Methods: Thirty athletes with a unilateral rupture of the Anterior Cruciate Ligament (ACL), classified as coper, were randomly assigned to perturbation and standard training groups. Intervention training results based on comparison of scores obtained from functional tests in 4 single-leg jump tests, scores of questioners, and surface Electromyography (sEMG) tests were determined between the two groups as well as between the two healthy and ACLD limbs in each group in the walking task.

Results: The perturbation training group showed a significant increase in muscle activity in both healthy and ACLD limbs with an increase in similarity index (SI) (p=0.08, ES=0.81), while in the standard training group the results were not significant (p=0.39, ES=0.39).

Conclusion: Individuals in the perturbation training group achieved higher scores on all tests compared to the standard training group. This means that the perturbation training group was more mentally and physically prepared in terms of strength, coordination and symmetry between the two limbs to participate in pre-injury sports levels.

Keywords: ACLD; Perturbation training; Walking task; Voluntary response index


ACLD: Anterior Cruciate Ligament Deficiency; sEMG: surface Electromyography; SI: Similarity Index; CNS: Central Nervous System; ES: Effect Size; VRI: Voluntary Response Index; SENIAM: Surface Electromyography for the Non-Invasive Assessment of Muscles; RVi: Response Vector; PRVi: Prototype Response Vectore


Anterior Cruciate Ligament Deficiency (ACLD) is one of the most common knee injuries in sports activities among young athletes [1] in the age group of 16 to 39 years with an estimated incidence of approximately 85 per 100,000 [2]. Commonly the following things have been reported to happen after an ACLD: reduced quadriceps strength [3-7], decreased knee function [4-6], deficits in proprioception and balance [6], abnormal gait patterns [4,5,7-10], asymmetry in both limbs [4,5], knee instability in daily and functional activities [1,4,5,11], reduction in range of motion [5], defective biomechanics [1], secondary knee injury and progression of osteoarthritis in the knee joint [1,4-6,8-10] due to its repetitive dynamic instability [1] all of which have imposed a lot of time,-socio-economic [12], as well as psychological [13] burdens on these patients.

In several studies, persistent abnormal changes in the kinematic and kinetic patterns of the lower limbs in gait activity have been reported following ACLD, which have still existed despite reconstructive surgery compared to healthy individuals [8,9]. Magnitude of shearing forces due to giving way and compressive forces caused by increased co-contractions happen in these individuals on areas of the joint’s cartilage that were not previously under load while walking, and the result is the occurrence of early degenerative changes in the knee joint [8-11].

Typically, reconstructive surgery is the selective treatment for athletes who want to return to high levels of sports (including jumping, cutting, and pivoting) to avoid secondary joint damage. However, several recent studies have showed successful non-surgical treatments at higher levels of sports [2,4]. Numerous studies have established documented non-surgical treatment algorithms for perturbation rehabilitation in ACLD patients [1,3-5,12,14], from which long-term success has been reported in patients returning to regular high levels of recreational or sports activities that require jumping, changing direction and rotation [14,15]. Perturbation or neuromuscular training improve the dynamic stability of the knee joint and normalize movement patterns of the knee while walking [3-5,12]. Studies on perturbation have shown that by stimulating the visual, vestibular, and proprioceptive systems, body sway increases, and by repetition, the Central Nervous System (CNS) tries to optimally balance mechanisms by reinforcing two feed-forward and feedback control strategies [16]. This model of neuromuscular control training helps to regain the lost coordination, balance, strength and skills by strengthening the joint muscles co-contraction, especially in the stabilizing muscles, to stimulate the stabilization reflex and prepare for the activity while creating functional stability of the joint by stiffening it [17]. In most studies, perturbation trainings have been used manually in different directions [1,11,12,14,15], and in recent studies, mechanical perturbation exercises have been used in limited directions. In the comparison results, it has been reported that mechanical perturbation trainings are preferable to the manual forms [1,4,5].

Surface Electromyography (sEMG) has been commonly used for more than 50 years in research studies of functional activity as well as gait [18,19]. Recording sEMG during voluntary motor work is relatively easy and non-invasive, and provides a quantitative measurement of the output of the CNS to the muscle. It is a reliable method for assessing altered motor control [20], and is commonly used in dynamic tests in ACLD individuals [18]. In most previous studies in the field of sEMG, muscle activity levels have been assessed on a muscle-by-muscle basis in a task, and mainly examined the onset/ off-set of muscle activity and the intensity of activity [21]. Due to the inherent limitations of sEMG recording and measurement during voluntary movement, attempts to quantitatively analyze motor control while walking are still unsuccessful [20]. In recent sEMG studies, instead of measuring the activity of each muscle alone, the EMG activity of all the muscles responsible for the activity as a whole is quantitatively measured in the work pattern. This type of measurement has a more objective evaluation, and it is called the Voluntary Response Index (VRI) [18,20]. All studies in this field have shown that this method has a high sensitivity in detecting altered patterns of muscle activity in people with movement disorders and has a high validity [21]. By studying the available articles, the effectiveness of manual and mechanical perturbation training for non-surgical treatment of ACLD individuals has been determined [1,3-5,11,12,14,15], although issues still exist in the employment of the training protocols regarding the use of specialized personnel, and the timings as well as characteristics of manual and instrumental training [1,4,5].

The aim of this study was to use internal-external mechanical perturbation training with a new training approach in all directions and at relatively high speeds similar to the occurrence of real events under controlled laboratory conditions in ACLD individuals. In this study, we want to compare ACLD individuals in two groups of internal-external mechanical perturbation training and standard training with each other as well as with their healthy limbs. It is hypothesized that with this treatment, the walking patterns of ACLD individuals become more synchronized and we can define a new approach to perturbation training in these individuals.



Thirty people (17 men and 13 women in the age range of 18 to 40 years) with complete unilateral rupture of the anterior cruciate ligament of the left knee were selected from the athletes referred to the clinic of the Sports Medicine Federation of the Islamic Republic of Iran (SMFIRI). All participants were first diagnosed by an orthopedic surgeon through clinical tests and MRI images and then referred to a sports physiotherapist to evaluate the inclusion and exclusion criteria. Then, they were randomly assigned to the perturbation training group (15 people) and also to the standard training group (15 people). This study was approved by the ethics committee of the Sports Sciences Research Institute (SSRI), (Approval ID was: IR.SSRC.REC.1399.095) and all participants accepted and signed the consent form to participate in this study before entering the study.

Training interventions

Standard group: The training protocol of this group was cardiovascular, lower extremity muscle strength, balance, core stabilization, agility and sport-specific exercises (according to Table 2). The training program of this group of participants was performed for 3 intermittent sessions at week for a month.