Thijs A. Heldoorn

Normative Spatiotemporal Parameters During 100-m Sprints in Amputee Sprinters Using Running-Specific Prostheses

The aim of this study was to develop a normative sample of step frequency and step length during maximal sprinting in amputee sprinters. We analyzed elite-level 100-m races of 255 amputees and 93 able-bodied sprinters, both men and women, from publicly-available Internet broadcasts. For each sprinters run, the average forward velocity, step frequency, and step length over the 100-m distance were analyzed by using the official record and number of steps in each race. The average forward velocity was greatest in able-bodied sprinters (10.04 ± 0.17 m/s), followed by bilateral transtibial (8.77 ± 0.27 m/s), unilateral transtibial (8.65 ± 0.30 m/s), and transfemoral amputee sprinters (7.65 ± 0.38 m/s) in men. Differences in velocity among 4 groups were associated with step length (able-bodied vs transtibial amputees) or both step frequency and step length (able-bodied vs transfemoral amputees). Although we also found that the velocity was greatest in able-bodied sprinters (9.10 ± 0.14 m/s), followed by unilateral transtibial (7.08 ± 0.26 m/s), bilateral transtibial (7.06 ± 0.48 m/s), and transfemoral amputee sprinters (5.92 ± 0.33 m/s) in women, the differences in the velocity among the groups were associated with both step frequency and step length. Current results suggest that spatiotemporal parameters during a 100-m race of amputee sprinters is varied by amputation levels and sex.

The fastest sprinter in 2068 has an artificial limb

Recent developments in carbon fiber running-specific prostheses (RSPs) with energy-storing capabilities have allowed individuals with lower extremity amputation (ILEAs) to regain the ability to run. This phenomenon exemplifies how ILEA sprinters are highly motivated and work hard as well as how current prostheses have advanced. This raises the following question: How fast would RSPs allow ILEA sprinters to run? Although several studies predicted limitations in sprint performance in able-bodied sprinters (ABSs),1,2 no studies have been reported for ILEA sprinters. We assessed the progression of the winning times of the men’s 100-m sprint in the Paralympics and compared them with those in the Olympics. The winning times of the men’s 100-m sprint in the Olympics were obtained from the official website of the Olympic Movement (http://www.olympic.org/). Data were available every 4 years from 1900 to 2012 except for 1912–1920 and 1936–1948 when the Olympic Games were cancelled due to World Wars I and II, respectively. We also acquired data for the winning times at the Paralympics from the official website of the Paralympic Movement (http://www.paralympic.org/). Data were available every 4 years from 1976 to 2012. In this study, we included the winning times of the men’s 100-m sprint in the C (1976 and 1980), A4 (1984), A4-A9 (1988), TS2 (1992), T43-44 (1996), and T44 (2000, 2004, 2008, and 2012) classifications. We performed regression analyses to predict the winning time for future Olympics and Paralympics for ABS and ILEA sprinters, respectively. Since the carbon fiber prosthesis was first seen in elite sporting events at the 1988 Paralympic Games,3 data for ILEA sprinters in 1976, 1980, and 1984 were excluded from the regression analyses. The 95% confidence intervals on the predicted winning times were also calculated in the analyses. The significance was set at p < 0.01 in each regression analysis. The difference in winning times between ABSs and ILEAs was over 4 s in 1976 (Figure 1). The ILEAs shaved approximately 1.5 s off the time difference from 1984 to 1988. This improvement may be attributed to the advent of carbon fiber prosthetic feet at the 1988 Paralympic Games.3 These results suggest that technological interventions, such as the advent of RSPs, would contribute to the improvement of the sprint performance of ILEAs. In other words, revolutionary new materials or technical advances may induce drastic performance improvements in the future, similar to that seen from 1984 to 1988. As of 2012, the difference between the two groups has gone down to 1.27 s. The current world records (as of 29 September 2014) are 9.58 s for ABS and 10.57 s for ILEAs, which represent a difference that is already less than 1 s. Our regression model predicted that ILEA sprinters would outperform ABS in 2068, where the predicted winning times could be 9.039 and 9.046 s, respectively. These results indicate that if current trends continue, the fastest sprinters in the world may be ILEAs from 2068 onward.

Step Frequency and Step Length of 200-m Sprint in Able-bodied and Amputee Sprinters

The goal of this study was to examine the hypothesis that the difference in the 200-m sprint performance of amputee and able-bodied sprinters is due to a shorter step length rather than a lower step frequency. Mens elite-level 200-m races with a total of 16 able-bodied, 13 unilateral transtibial, 5 bilateral transtibial, and 16 unilateral transfemoral amputee sprinters were analyzed from publicly available internet broadcasts. For each run, the average forward velocity, step frequency, and step length over the entire 200-m distance were analyzed for each sprinter. The average forward velocity of able-bodied sprinters was faster than that of the other 3 groups, but there was no significant difference in average step frequency between able-bodied and transtibial amputee sprinters. However, the average step length of able-bodied sprinters was significantly longer than that of the transtibial amputee sprinters. In contrast, the step frequency and step length of transfemoral amputees were significantly lower and shorter than those of the other 3 groups. These results suggest that the differences in 200-m sprint performance between able-bodied and amputee sprinters are dependent on amputation level.

Wearing inappropriate footwear increases the loading rate during running

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Physical activity classification using shoe-mounted sensors and confidence regions

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Plantar loading in an amputee runner using running-specific prostheses with a rubber sole

Carbon fibre running-specific prostheses (RSPs) have allowed individuals with lower extremity amputation (ILEA) to actively participate in sporting activities including competitive sports. In spite of this positive trait, the RSPs have not been thoroughly evaluated regarding potential injury risks due to abnormal loading during running. For example, lower extremity injuries are more common in amputee athletes and typically occur during running activities (Ferrera & Peterson, 2000). Furthermore, these injuries are thought to be mainly attributed to the mechanical stress of the vertical ground reaction forces during running (Aruin, 2000; Feldmann et al., 2000), evidence regarding the abnormal loading in ILEA during running has not been reported. Centre of pressure (COP) trajectories have been used as a tool for describing and assessing the effects of shoe or orthotic interventions (Nigg, Stergiou, Cole, Stefanyshyn, M€undermann, & Humble, 2003). Despite the fact that analysis of plantar loading is also informative regarding risks for sustaining common overuse running injuries, little is known about plantar loading patterns during running in amputees using RSPs.