Discussion

DISCUSSION

The purpose of this study was to identify the effect of heel height on the angles of the ankle and knee, step length, stride length, and stride rate. We hypothesized that with increasing heel height, the ankle would increase plantar flexion (yielding higher ankle angles), while the knee would increase flexion (yielding lower knee angles). We also hypothesized that increasing heel height would cause decreased step length and stride length, and increased stride rate.

After analyzing these variables in each condition (tennis shoes, low heels, and high heels), it was found that as heel height increases, plantar flexion of the ankle increases. This is shown in Figure 1 as high heels consistently demonstrate the greatest plantar flexion of the ankle. Additionally, we found that as heel height increases, flexion of the knee increases. This is shown in Figure 2 wherein high heels generally demonstrate the greatest flexion of the knee. However, in % Gait 43.2 to 80, the tennis shoes condition has the greatest knee flexion. This may be a result of human error, as potential sources of this discrepancy include placement of the markers on the subject's clothes rather than directly on their bones. These results could also be attributed to technical difficulties posed by PowerChalk. Moreover, we discovered that as heel height increased, step and stride length decreased consistently across all conditions, as seen in Table 1.

As expected, it was found that stride rate in heels was higher compared to that in tennis shoes, though it was found that low heels actually had the highest stride rate. This went against our initial hypothesis which suggested that the highest heels would yield the highest stride rate. There was only a small difference between the two conditions (stride rates of 0.792 versus 0.789, seen in Table 1). Further testing with more trials would be ideal to determine if this result is just an error, or if there is significance to it.

When compared to existing research, the findings of our study are predominantly consistent. Shorter step lengths were associated with wearing high heels, as was seen in previous studies (Opila-Correia, 1990) (Wiedemeijer & Otten, 2018). A decreased stride length and an increased stride rate were also observed in our study. These findings have been demonstrated previously in research conducted on a similar subject demographic (Barkema et al., 2012). As mentioned, however, lower heels were associated the highest stride rate, which is inconsistent with prior evidence that found higher heels to have the greatest effect (Barkema et al., 2012). Our findings regarding joint angles of the ankle and knee also correspond to existing research, with high heels yielding an increase in plantar flexion at the ankle joint and an increase in flexion at the knee joint (Wiedemeijer & Otten, 2018) (Barkema et al., 2012). This held true for all data besides the aforementioned % Gait span in Figure 2 for tennis shoes, which could possibly be attributed to human error.

Though our findings generally supported our hypothesis, there were some limitations to this study. One limitation is the use of the adhesive markers to the subject's clothes. Though researchers aimed to put the markers as accurately as possible on the anatomical landmarks of interest, these markers are not as accurate as those directly on the skin (where bones may be visible), or directly on the bones themselves (which is much more invasive). Another limitation is that the shoes worn by the subject were not her own, and did not fit properly. They were slightly big, so researchers tried to remedy this by having the subject wear socks, but slightly big sizing could have still influenced the subject's gait. The two heels used were also slightly different styles, as one had a strap around the ankle and the other did not. Ideally heels of the same style but different heel heights would be used to limit other variables or influences on the results. Additional limitations include the small size of the study. Only one participant was used, with one trial in three different conditions. This lowers the generalizability or external validity of the study, meaning the study's results are mainly relevant for the subject herself, but may not apply well to others. Future studies may involve a larger, more diverse sample so that generalizability is increased, and with more trials within each condition to evaluate consistency of results. There may have also been some human errors associated with filming, and technical difficulties associated with the use of PowerChalk, both on the manufacturer and user ends, though neither of these are thought to have greatly influenced study results.

Due to the common use of high heels among women, it is important to further investigate the long-term effects of high heel wearing on an individual's gait and what future health implications this may cause. Additionally, one might consider the mediation of several factors within the relationship between heel height and the gait cycle, including greater experience and comfortability with wearing high heels.

In conclusion, high heels do have an effect on gait, including step length, stride length, stride rate, and the angles of the ankle and knee, as well as many other aspects that were not investigated in this study. Our hypotheses were supported, as increased heel height was associated with an increase in plantar flexion of the ankle and flexion of the knee. Additionally, stride length and step length decreased while stride rate increased with heels compared to tennis shoes. Overall, these findings are relevant to women in their daily lives as they try to navigate wearing high heels, despite their limitations.