## 4 Discussion
This finding is in accordance with [PERSON] et al., who examined dynamic stability control during stair descents and found that, when compared to younger adults, older adults are at greater risk of falling due to their body's lowered safety control ability with respect to the CoM while stepping down [14]. Our results are also in accordance with [PERSON] et al., who investigated CoM vertical velocity profiles, reporting that the peak downward CoM velocity was significantly reduced by age [15]. The previous literature has also found that older adults may adopt a stair descent strategy where the downward CoM velocity is limited to decrease fall risks [16], with the reduced peak occurring approximately at the instant of contact with the step below [15]. Greater FP [16] and reduced FC have been associated with a higher risk of falling during stair negotiation [18]. [PERSON] et al. reported that falls during stair descent are more likely to occur near the bottom of the staircase, when older adults tread on the last step [18], so it was important to analyze FC and FP during this transition. Our results showed that older adults with and without HoF and FoF present similar strategies when negotiating FP and FC, leaving and reaching the steps within a reasonable distance in a safe manner. [PERSON] et al. analyzed the influence of age and step height inconsistency on FP and FC, reporting significantly greater FP in older adults when comparing the same steps [16]. Their study states that this finding is related to the more cautious stepping strategies adopted by older adults, which increase the chances of overstepping and the foot slipping forwards over an edge, causing a backward loss of balance and possibly a fall [16]. However, their study could not establish an association between age and changes in FP and FC on the last step, similarly to our results, which were not able to associate HoF and FoF with lower FC and greater FP. This could be related to the chosen moment of FP and FC data extraction in both protocols, given that when the limb leaves the last step and initiates gait transition, the vertical and horizontal distance of the foot to the step is considerably higher because there is no step below to limit its trajectory [15]. Within the stair cycle, it was important to analyze the lower-limb joint angles at the instant of the aforementioned events because their reduction in older adults has been reported to result in a higher risk of falling [2]. Our results do not demonstrate the influence of HoF and FoF on lower-limb kinematics, given that the participants exhibit similar position angles. It is also not possible to compare our results to other studies, given that, to the best of our knowledge, no authors have focused on the lower-limb joint position at specific FC and FP events. In the gait cycle, we analyzed lower-limb joint angles at HS and TO after stair descent. These events are the most significant given that the previous literature has found that older adults present altered lower-limb joint motion [20], resulting in limited capacities in limb advancement during gait [17]. Our results showed that participants exhibited similar angles in the hip and knee joints; however, regarding the ankle, older adults with HoF and FoF adopted different angle positions. This resulted in different ankle strategies, specifically diminished ankle dorsiflexion at HS and diminished plantarflexion at TO. Reduced hip and ankle angles are the most consistent finding among older adults [38]; however, only significant differences were present at the ankle in participants with HoF and FoF. Our study found that older adults with FoF adopted significantly reduced ipsi ankle angles at HS, in accordance with [PERSON] et al., who compared older and younger adults, reporting reduced ankle dorsiflexion at HS in older adults [47].