The dataset was collected from experiments with six young, healthy participants who were instructed to perform two-legged hopping at a self-selected frequency on a specially designed platform capable of applying vertical perturbations. The platform introduced a controlled downward displacement of 7.5 cm during ground contact. Each trial lasted 20 seconds, during which participants completed approximately 30 hops. In each trial, one perturbation was delivered at an unpredictable moment. Each participant performed three trials, with each trial targeting a different phase of the stance period. To reduce fatigue and limit any anticipatory reactions, a two-minute rest period was provided between trials. Although participants were informed that perturbations would occur, they were not told the specific timing within each trial. Due to the short duration of each hop and stance phase, it was unlikely that participants could predict exactly when the perturbation would happen, ensuring that their reactions were primarily reflexive. Hopping consists of two phases: the stance phase, when the feet are in contact with the ground, and the flight phase, when the body is airborne. In this study, the focus was on perturbations applied during the stance phase, which was divided into three subphases according to the vertical motion of the center of mass (CoM): Early Stance Perturbation (ESP): Occurring during the first 40% of the stance phase, with the full platform displacement happening during ground contact. Mid-Stance Perturbation (MSP): Taking place between 40% and 60% of the stance phase, with take-off occurring as the platform is still moving downward. Late Stance Perturbation (LSP): Beginning in the final 40% of the stance phase, where most of the platform movement happens after take-off during the flight phase. These conditions were designed to investigate how the timing of ground-level downward perturbations during stance influences participants’ recovery strategies. For motion capture, 20 reflective markers were positioned on specific anatomical landmarks, including the acromion, anterior and posterior superior iliac spines (ASIS and PSIS), heels, and the lateral and medial sides of the knees, ankles, and toes. Marker trajectories were recorded using a 10-camera infrared motion capture system at 500 Hz. Ground reaction forces (GRF) were measured using a 3D force plate (1 kHz), which was integrated into the perturbation platform. The study received ethical approval from the Technical University of Darmstadt (approval ID EK 11/2015) and was conducted in accordance with the Declaration of Helsinki. All participants provided written informed consent before taking part in the study.