Effect of a shock-absorbing pylon on transmission of heel strike forces during the gait of people with unilateral trans-tibial amputations: a pilot study.

The primary objective was to test the hypothesis that walking with a shock-absorbing pylon (SAP) decreases the peak magnitude and frequency content of the heel-strike-initiated shock wave transmitted to the stump. The secondary hypotheses were that walking with a SAP decreases the heel-strike transient force between the ground and the foot and increases function as measured by walking velocity and subjective assessments. Seven people with unilateral trans-tibial amputations walked at self-selected speeds without and with a SAP. As the primary outcome measure, accelerometers were used mounted proximally and distally along the prosthetic pylon to measure the transmitted shock wave. Secondary measures included ground reaction forces from a force plate, a ten-minute walking test to determine walking speed and a questionnaire to evaluate gait function and subjective preference. The SAP provided no significant shock absorption as indicated by either the mean peak proximal accelerations of 3.19 g and 2.82 g (p = 0.28) without and with the SAP respectively or the mean difference between the peak proximal and distal accelerometers, 0.16 g and 0.19 g (p = 0.58). No significant change in the frequency content was found. Variances were high. There were no significant differences noted in the secondary measures. Although this study failed to identify any statistically significant effects due to the SAP, the magnitude and variance of the data will permit an accurate estimation of the appropriate sample size for future studies required to determine the efficacy of SAPs.

Effect of a high-rolling-resistance training method on the success rate and time required to learn the wheelchair wheelie skill: a randomized controlled trial.

OBJECTIVE: The primary objective of this study was to test the hypotheses that a wheelie training method that begins in a high-rolling-resistance (RR) setting (1) improves the success rate and (2) reduces the training time. Our secondary objectives were to assess the effects of other factors (e.g., age, gender) on training time and to acquire data on the perceptions of the participants that would assist us in refining our training methods. DESIGN: Randomized controlled study including 48 able-bodied participants with no significant wheelchair experience. Each participant was taught the wheelie skill, using up to five training sessions. Participants in the conventional group did all of their training on a smooth, level, tile surface. The RR group began training in a high-RR setting (rear wheels initially prevented from moving at all, progressing to being on 12-cm-thick foam that permitted some movement) before moving to the tile surface. Outcome measures were success rate (%), training time (mins) to achieve wheelie competence (defined as the ability to perform two consecutive 30-sec wheelies within a 1.5-m-diameter circle, assessed at least 2 days after training), and a questionnaire. RESULTS: The success rates for those in the conventional and RR groups were 96% and 100%, respectively (P = 1.000). The mean (+/-SD) training times for the conventional and RR groups were 55.9 mins (+/-27.1) and 51.8 mins (+/-18.7) (P = 0.549). Training time was not significantly affected by trainer or age, but it was affected by sex, with women requiring an average of 21.4 mins more than men (P = 0.002). Perceptions of participants in both groups about the training were positive. Of the participants in the RR group, 14 (74%) perceived the RR technique as "very effective," and five (26%) perceived it as "moderately effective." CONCLUSIONS: Neither success rate nor training time for wheelie skill acquisition by able-bodied learners are improved by a training method using high RR. Women require more time to learn than men. Learners using the RR technique perceive it to be effective. These results have implications for training practices.

The effect of rolling resistance on stationary wheelchair wheelies.

OBJECTIVE: To test the hypotheses that increased rolling resistance (RR) reduces rear-wheel displacement and perceived difficulty during the takeoff and balance phases of stationary wheelchair wheelies. DESIGN: We carried out within-subject comparisons of 20 participants as they each performed, in random order, two 30-sec stationary wheelies in three RR settings (tile, 5-cm-thick foam, and 12.5-cm-high blocks in front of and behind the rear wheels). The main outcome measures were rear-wheel displacement (in centimeters for the takeoff phase and centimeters per second for the balance phase) from a spring-loaded potentiometer and Likert scales of perceived difficulty. RESULTS: For rear-wheel displacement, all six of the pairwise comparisons (three terrains x two phases (takeoff and balance)) showed a significant statistical difference (P < 0.002). In each of the six pairwise comparisons, displacement was less for the higher of the two RR conditions. For perceived difficulty, during the balance phase, participants perceived tile to be significantly more difficult than either foam (P = 0.0067) or blocks (P = 0.0002). The other pairwise comparisons were not statistically significant. CONCLUSION: In conditions of increased RR, rear-wheel displacement and perceived difficulty are reduced during stationary wheelchair wheelies. These findings have implications for teaching wheelchair users to perform wheelies, a foundation of many advanced wheelchair skills.