Gait analysis is the systematic study of human locomotion, quantifying movement patterns and biomechanics using observation and advanced instrumentation. By capturing and interpreting physical parameters, specialists identify abnormalities, inefficiencies, or compensatory movements often invisible to the unaided eye. The resulting data serves as a diagnostic tool, providing an objective assessment of overall movement mechanics.
Defining the Key Parameters of Human Gait
The analysis of human gait is structured around two main categories of quantitative measurements: temporal and spatial parameters.
Temporal parameters are time-based metrics defining the rhythm and sequencing of the walking or running cycle. These include cadence (steps taken per minute) and step time (the duration of a single step). The gait cycle is divided into the stance phase (foot on the ground) and the swing phase (foot moving forward). The proportion of time spent in the double support phase, where both feet are simultaneously on the ground, is also measured as it relates to stability.
Spatial parameters focus on the distances and positions involved in locomotion. Stride length measures the distance from the heel strike of one foot to the next heel strike of the same foot, representing a complete gait cycle. Step length is the distance between the heel strike of one foot and the heel strike of the opposite foot. Step width, or the base of support, measures the lateral distance between the center of the two feet during successive steps.
Technology Driving Modern Analysis
The precision of modern gait analysis relies on sophisticated technology to accurately capture the complexity of human movement.
Motion capture systems use multiple high-speed infrared cameras to track the three-dimensional position of reflective markers placed on specific anatomical landmarks of the body. This process, known as kinematics, records the angles, velocities, and accelerations of joints and body segments throughout the movement. The resulting data allows for the reconstruction of the entire body’s motion, providing a detailed view of joint mechanics.
Force plates, specialized sensors embedded in the floor or treadmill, measure the kinetics of gait. These plates quantify the ground reaction forces (GRF) that the body exerts on the walking surface. This measurement helps determine the magnitude and direction of forces acting on the joints, as well as the pressure distribution across the foot during contact. Some systems also use instrumented insoles, which are thin pressure-resistive sensors placed inside footwear to collect force and pressure data during multiple gait cycles.
Electromyography (EMG) records the electrical activity of muscles during the gait cycle. Electrodes are placed on the skin over specific muscles to measure when a muscle turns on and off and how intensely it is working. This provides insight into the timing and coordination of muscle activation, which helps identify neuromuscular issues or muscle imbalances contributing to an abnormal gait pattern.
Clinical and Athletic Applications
Gait analysis is a valuable tool with applications across clinical medicine and athletic performance enhancement. In clinical settings, it provides objective data for diagnosing and managing conditions affecting movement. For individuals with neurological disorders such as Parkinson’s disease or stroke, the analysis quantifies impaired balance, reduced walking speed, or asymmetrical movement patterns. This information helps clinicians tailor treatment plans, such as optimizing orthotic devices or planning therapeutic interventions for spasticity.
Orthopedic Assessment
For orthopedic patients, gait analysis assesses chronic pain and musculoskeletal issues involving the hip, knee, or ankle. It identifies subtle biomechanical inefficiencies or compensatory movements that contribute to overuse injuries or joint stress. The analysis results guide surgical planning and measure the effectiveness of rehabilitation programs, providing a quantified reference point for tracking recovery progress.
Athletic Performance
In sports, particularly for runners, the analysis optimizes performance and reduces injury risk. By analyzing the athlete’s running mechanics, specialists identify inefficiencies like excessive pronation or a low cadence, which affect speed and endurance. The data helps in selecting appropriate footwear or designing targeted strength and conditioning programs to correct movement flaws. The goal is to improve the efficiency of the gait cycle, allowing the athlete to move more effectively while minimizing stress on joints and tendons.
Preparing for a Gait Analysis Session
Preparing for a gait analysis session involves ensuring the movement can be clearly captured by the equipment. Subjects are advised to wear tight-fitting exercise clothing, such as shorts or compression tights, to allow for the proper placement of reflective markers directly onto the skin over specific joint centers. Loose clothing can obscure these markers, compromising the accuracy of the motion capture data.
It is helpful to bring the footwear normally worn for walking or running, as the analysis may include testing those shoes to assess their contribution to the gait pattern. The session usually involves the subject walking or running on a treadmill or specialized walkway at a comfortable pace. Subjects must move naturally and avoid consciously altering their usual walking or running style during data collection. The entire procedure typically takes a few hours.