Author(s): EMAM, M., HORVÁTH, A., KOVÁCS, B., CSIZMADIA, B., YE, J., HORTOBÁGYI, T., Institution: SEMMELWEIS UNIVERSITY , Country: EGYPT, Abstract-ID: 2442

INTRODUCTION:
Eccentric overload resistance training has been proposed to induce distinct neuromuscular adaptations compared to traditional resistance training. However, its effects on gait and functional tasks such as sit-to-stand (STS) remain understudied. This pilot study examined the effects of eccentric overload resistance training (experimental group) compared with concentric overload training (control group) on gait and STS biomechanics using markerless motion capture. We hypothesized that eccentric compared with concentric overload training would induce greater changes in lower-limb kinematics, particularly during the STS task.
METHODS:
Ten healthy older adults were randomly allocated to an eccentric overload group (ECC, n = 5, 3 females) or a concentric overload control group (CON, n = 5, 2 females). Gait and STS performance were assessed pre- and post-intervention using OpenCap markerless motion capture. Participants performed five gait trials a metronome-controlled fixed cadence and averaged per participant. They also performed three STS trials, and the fastest trial (based on total time) was included in the analysis. Linear mixed-effects models (LMMs) were used to analyze spatiotemporal gait and scalar STS outcomes. Lower-limb joint kinematics throughout the movement cycle were analyzed using Statistical Parametric Mapping (SPM).
RESULTS:
LMMs revealed no significant group, time, or interaction effects for spatiotemporal gait parameters or scalar STS outcomes. Gait speed remained stable in both groups (ECC: 1.44 ± 0.11 to 1.35 ± 0.45 m/s; CON: 1.60 ± 0.29 to 1.58 ± 0.27 m/s), and cadence also remained unchanged (ECC: 115.2 ± 4.34 to 114.3 ± 3.93 steps/min; CON: 114.9 ± 12.43 to 115.2 ± 10.87 steps/min).
Descriptively, the CON group reduced STS total time from 11.2 ± 2.14 s to 8.4 ± 1.97 s and increased STS mean velocity from 0.40 ± 0.068 m/s to 0.54 ± 0.131 m/s, whereas the ECC group showed minimal change (8.03 ± 1.36 s to 8.22 ± 2.33 s; 0.500 ± 0.082 m/s to 0.508 ± 0.123 m/s). In contrast, SPM identified a significant main effect of group in knee joint kinematics during 50–60% of the STS movement cycle. This phase corresponds to the late rising phase, approaching full knee extension. The ECC group demonstrated altered knee joint excursion during this portion of the movement compared to the CON. No significant kinematic differences were observed during gait or during other phases of the STS cycle

CONCLUSION:
Eccentric overload resistance training was associated with task-specific differences in knee joint kinematics during the late rising phase of the STS task, suggesting potential alterations in movement strategy rather than changes in overall task performance or gait parameters. No preferential improvement was observed for eccentric versus concentric overload training in spatiotemporal gait or scalar STS outcomes. These preliminary findings highlight the need for larger studies to confirm whether eccentric training induces meaningful neuromuscular adaptations.