Running-specific prostheses limit ground-force during sprinting

Abstract

Running-specific prostheses (RSP) emulate the spring-like behaviour of biological limbs during human running, but little research has examined the mechanical means by which amputees achieve top speeds. To better understand the biomechanical effects of RSP during sprinting, we measured ground reaction forces (GRF) and stride kinematics of elite unilateral trans-tibial amputee sprinters across a range of speeds including top speed. Unilateral amputees are ideal subjects because each amputee's affected leg (AL) can be compared with their unaffected leg (UL). We found that stance average vertical GRF were approximately 9 per cent less for the AL compared with the UL across a range of speeds including top speed (p < 0.0001). In contrast, leg swing times were not significantly different between legs at any speed (p 5 0.32). Additionally, AL and UL leg swing times were similar to those reported for non-amputee sprinters. We infer that RSP impair force generation and thus probably limit top speed. Some elite unilateral trans-tibial amputee sprinters appear to have learned or trained to compensate for AL force impairment by swinging both legs rapidly.

Development of a Wearable Sensor System for Dynamically Mapping the Behavior of an Energy Storing and Returning Prosthetic Foot

“…The system could also be developed to display live properties of the foot, data from the previous stride and wireless transfer to a laptop or tablet device, rather than having to manually download data with a cable at each juncture. Such an approach has been adopted previously in studies with great success [15], [26].…”

“…allowed all of the desired variables to be recorded whilst also allowing the amputee athlete as much flexibility as they would ordinarily have had. Grabowski et al [26] notes that Some Paralympic sprinters regularly add 100-300 grams over the forefoot region of their foot during competition because they feel it helps them achieve a more symmetrical gait. However, the participant was unable to notice the change in mass (additional 148 grams) in this study.…”

Running-specific prostheses: The history, mechanics, and controversy

“…12) suggested that the low mass and inertia of RSPs did not facilitate unnaturally fast leg swing times, and that fast leg swing times could result from learning and/or training.…”

“…On the other hand, Grabowski et al 12) compared the contact length between intact and prosthetic legs in six unilateral transtibial runners using a treadmill. The authors found that the subjects in their study increased the contact length at faster speeds for both, the intact and prosthetic leg, but there were no significant differences in the contact length between the legs.…”

“…They found that the vGRF was significantly higher in the able-bodied athletes than in the double amputee sprinter. Similarly, several studies reported that the RSPs would impair force generation and thus likely limit top speeds 12,[14][15][16] .…”