Background: Low Back Pain Comprises an Extremely Common and Costly Condition that Represents the Leading Cause of Disability Globally. Usually, Low Back Pain Presents a Nonspecific
Etiology and its Recurrences are Common. Despite Epidemiologic Data Involved Mainly Non-Athletes, Nonspecific Low Back Pain is also a Common Finding Between Athletes of Different Modalities. Among
Different Aspects Related to Nonspecific Low Back Pain, Issues Related to Motor Control are the Focus of the Present Study. For Example, Anticipatory Postural Adjustments (APA) are Achieved from a
Main Control Mechanism Named Feedforward, Which is Responsible for Predicting Disturbances and Producing Adequate Responses that Maintain Stability. This Aspect of Motor Control Could be Influenced by
the Low Back Pain Symptoms. Among Different Motor Tasks to Investigate APA, we Selected Gait Initiation, which is a Functional Task and Corresponds to the Transition between an Upright Quiet Stance
and the Execution of the First Step. In this Way, the Main Goal of this Study was to Compare Gait Initiation in Younger Adults with and without Nonspecific Low Back Pain Symptoms.
Methods: Eleven Individuals with Nonspecific Low Back (“LBP group”) and 11 Individuals without LBP Symptoms (“Control Group”) Paired by Sex, Age and Anthropometric Characteristics
Participated in the Study. All Participants were Requested to Stand Still with One Foot on Each Force Plate, Side-by-Side, and Body Weight Evenly Distributed Between both Feet. At a Verbal Command,
they Should Start Walking with Right Foot at a Comfortable and Self-Selected Speed. Reflective Markers were Placed Bilaterally on Heel and Third Metatarsal Head in Order to Detect the Following
Events: Heel-Off and Toe-Off of both Feet, and Heel Strike of Step Foot. From Force Plates’ Data, Ground Reaction Forces and Center of Pressure (CoP) in the Anterior-Posterior (AP) and Medial-Lateral
(ML) Directions were Calculated. From the Events and CoP, APA Duration and Displacement on AP and ML Directions were Calculated.
Results: Participants from LBP Group Presented Longer APA Duration and Reduced Displacement of CoP in the AP Direction Compared to Participants from Control Group. No Difference was
Found for the Displacement of CoP in the ML Direction.
Conclusions: APA are Determined by Descending Commands from Central Nervous System prior the Execution of Any Voluntary Movement. In Gait Initiation, APA Consists of a Backward and
Lateral Displacement of CoP. Since Individuals with Nonspecific LBP Symptoms Presented Reduced Backward Displacement and Longer Duration of APA Compared to Individuals with no LBP Symptoms, we can
Suggest that LBP Symptoms can Influence the Feedforward Control of Voluntary Movement, Mainly in the AP Direction which is the Progression Line of Gait.