Final Answer:
Max IR is reached at 30-40% percent of gait (option C).
Step-by-step explanation:
The maximum initial contact reaction force (Max IR) occurs at approximately 30-40% of the gait cycle (option C). During the gait cycle, different phases contribute to the forces experienced by the lower extremities, and Max IR corresponds to the point where the heel contacts the ground.
This occurs during the initial portion of the stance phase, and the specified percentage range reflects the typical timing of Max IR in relation to the entire gait cycle. Understanding the distribution of forces during gait is essential in biomechanics and rehabilitation.
The timing of Max IR provides valuable information for clinicians and researchers studying gait patterns, as alterations in this force can be indicative of various musculoskeletal and biomechanical conditions. Thus, recognizing the specific percentage range associated with Max IR aids in the assessment and management of gait-related issues.