## 4 Discussion  
The aim of the present study was to determine the level of association of the spatio-temporal gait parameters in both subjects with and without plantar fasciopathy. The second objective was to analyze whether differences in the spatio-temporal gait parameters exist between groups. The spatio-temporal gait parameters in people with bilateral plantar fasciopathy that had statistical significance when compared to the control group were: decreased step length (\(p<0.001\)), increased contact phase (\(p<0.001\)), increased double support (\(p<0.001\)), increased response to load (\(p<0.001\)), increased pre-swing (\(p<0.001\)), increased gait cycle (\(p<0.001\)), decreased stride (\(p<0.001\)), decreased speed (\(p<0.001\)), decreased cadence (\(p<0.001\)), and increased propulsion phase (\(p<0.001\)). Gait analysis has been shown to be an objective tool for assessing PF and the changes obtained after a treatment program [29]; however, the effect that bilateral PF has on the gait has not been frequently reported in the literature [30]. Thus, increasing knowledge about gait parameters and the clinical usefulness that it has in patients with bilateral PF is of clinical importance. Our results showed a strong correlation (0.671) between step length (mean 52.1 s) and cadence (mean 83.30 gait cycle/s) in the injured group; however, this correlation did not exist (0.173) in the healthy group (58.85 s-110.81 gait cycle/s). Differences may be explained, since patients suffering from PF have a different step length which affects the normal cadence of the human gait, probably because they suffer from pain when they are walking. This fact is also true with the stride and the propulsive phase in the injured group. Both spatio-temporal gait parameters have a moderate and negative correlation between them (\(-0.506\)); when the stride increases, the propulsive phase decreases; however, this is not the case for the healthy group. Stride (mean 104.2 cm) also has a strong correlation (0.671) with cadence (mean 83.3 gait cycle/s) for patients with PF; however, this correlation does not exist (0.172) in the healthy group (117.7 cm-110.81 gait cycle/s). This may also be explained due to the absence of pain in healthy subjects during walking, which allows them to take longer strides in order to walk faster, thus producing a shorter propulsion phase. In addition, patients with PF have a longer propulsion phase than the control group; for the injured group, 0.45 s; and for the control group, 0.21 s. This condition is produced when the plantar fascia is altered, resulting in the windlass mechanism being activated with greater difficulty, and this produces a late lifting of the foot. Thus, our results may explain the posture and the motion adopted during walking that are shown in subjects with bilateral PF, which may also present similar symptoms to those suffering from low back pain, with a greater amplitude of activation in the paraspinal muscles [31]. Furthermore, the aforementioned adopted posture and motion may be explained by the decreased velocity of the transverss, with the counter-rotation between the thorax and the pelvis, and that it globally affects the mean erector spinae function [31]. Figure 3: Scatter plots on the variables with the most significant results. Constant line is the linear regression and spot line is the logistic regression of the variables. These findings are in line with previous studies that have been carried out on patients with unilateral PF [29; 32]. In each scatter plot, the difference of each variable between the two groups studied can be observed. It is observed that in the group of patients without pathology, all of the subjects have similar values, as in the distance, they perform in the cadence and the step, unlike the subjects with FP, who obtain results with a greater variability of data between them, which may be due to the influence of the degree of pain on the gait cycle. [PERSON] et al.