## 4 Discussion
Regarding spatiotemporal parameters, [PERSON], [PERSON], and [PERSON] [14] described that 60 s of Counter-Movement Jumps fatigue protocol increased the stride frequency when the speed was constant, with no modifications in stance time, swing time, stride length, and vertical stiffness. However, in our research, stride frequency was not modified after peripheral fatigue. As far as we know, few studies analyzed the effects of muscular fatigue in spatiotemporal parameters during running, so more investigations are needed to clarify this disagreement. The third hypothesis, that central fatigue increased to a greater extent the range of movements of the lower limb in absorption and propulsion phases and stance time than peripheral fatigue, was supported. For all we know, there are no studies that compare the effects of central and peripheral fatigue in angular kinematics during running. In our investigation, the differences between the effects of central and peripheral fatigue were found during the absorption phase, showing similar effects in take-off and oscillation phases. Compared to peripheral fatigue, central fatigue caused greater increases in thigh and knee flexion, and ankle position was more dorsiflexed during the initial contact and maximum absorption phases. It could describe compensatory adaptations to maintain balance by shifting the body's center of mass [10,35] and to reduce the vGRF [7,41], diminishing knee loading without increasing the energetics or biomechanics demand in ankle [47]. These postural forward modifications and the decreased strength of knee extensors [47] would explain the higher increase of propulsion time after central than peripheral fatigue. Furthermore, the increment of range of movements during the absorption phase after central fatigue would be responsible for the increased stance time [8,11,16,17,37,45]. Peripheral fatigue produced a higher extended hip and knee during the initial contact and also during the maximum knee flexion phase compared to central fatigue. This greater knee extension during stance increases the vGRF received [6,7], and it may increase the risk of lower extremity injuries [6,7,11]. Moreover, the greater plantar flexion during peripheral fatigue to compensate the absorption with ankle and foot could override these structures and lead to injuries [44]. Running patterns in a central fatigue state were characterized by an increase in ranges of movement oriented toward a greater hip and knee flexion and ankle dorsiflexion during the initial contact and maximum absorption, increasing the stance time and propulsion time. While running with peripheral fatigue in quadriceps and hamstrings muscles was based on an increase in hip and knee extension during phases dedicated to the cushioning. Finally, this study had some limitations. Firstly, although there are studies that suggest that fatigue affects the dominant and non-dominant limbs in a similar way [48], we believe that the analysis of the two limbs could provide an extra quality to this research. Fatigue only of the dominant limb could cause the athlete to run compensating for this fatigue with the non-dominant and non-fatigued leg. However, the time required to fatigue both limbs on the isokinetic dynamometer was too long, and it could compromise the state of fatigue by helping the first-place fatigued leg to recover. Secondly, the infrared camera system used did not allow both extremities to be recorded at the same time, which is an aspect that would have provided more information on the processes of fatigue in athletes. The authors believe that future research should focus on knowing the effect of central and peripheral fatigue in both extremities at the same time, seeking protocols and instruments that allow a specific muscle group to be locally fatigued in both extremities at the same time, in addition to using a three-dimensional filming system that allows both extremities to be recorded during running.