As a fundamental motor pattern, the ability to run at a range of constant speeds is a prerequisite for participating in competitive games and recreational sports. However, it remains unclear how individuals with unilateral transfemoral amputations modulate anterior and posterior ground reaction force impulses (GRFIs) to maintain constant running speeds.
The study aimed to investigate anterior and posterior GRFIs across a range of constant running speeds in runners with unilateral transfemoral amputations wearing a running-specific prosthesis.
Eleven unilateral transfemoral amputee runners ran on an instrumented treadmill at five different speeds (30 percent, 40 percent, 50 percent, 60 percent, and 70 percent of the average velocity of their 100m personal records). Anterior-posterior ground reaction forces (GRFs) were measured at 1000 Hz over 14 consecutive steps. Impulse, magnitude, and duration of anterior and posterior GRFs were compared between the affected and unaffected limbs at each speed.
The net anterior-posterior GRFI, reflecting the changes in horizontal running velocity, was consistently positive (propulsion) in the affected limb and negative (braking) in the unaffected limb at all speeds.
Regardless of running speed, the study found that runners with unilateral transfemoral amputations can maintain constant running speeds not over each step, but over two consecutive steps (i.e., one stride).
The study, Anterior-posterior ground reaction forces across a range of running speeds in unilateral transfemoral amputees, was published in the Sports Biomechanics Journal.
