The dataset was collected to investigate muscle responses under different loaded walking conditions (0kg, 2kg, 4kg, 8kg). Thirteen participants (age: 27 ± 5 years; height: 1.82 ± 0.07 m; body mass: 81 ± 11 kg) took part in the experiment. Participant data was anonymized. Data were recorded while participants walked on an instrumented treadmill at a constant speed of 1.3 m·s⁻¹ (ADAL-WR, HEF Tecmachine, Andrézieux-Boutheon, France). Surface electromyography (EMG) signals were acquired bilaterally from seven muscles: rectus femoris, vastus lateralis, gluteus maximus, biceps femoris, tibialis anterior, gastrocnemius lateralis, and soleus. EMG data were collected using a wireless system (Trigno Avanti, Delsys, Natick, MA, USA), with sensor placement following SENIAM guidelines (www.seniam.org). EMG signals were sampled at 1925.9 Hz. Each EMG sensor also incorporated a triaxial gyroscope sampling at 148 Hz to measure three-dimensional angular velocity. In addition, one EMG sensor including the IMU was mounted on each dumbbell (left and right) to capture times with and without additional weight. Vertical GRFs were recorded for the right and the left limb (100Hz) from the instrumented dual force plate treadmill (ADAL-WR, HEF Tecmachine, Andrezieux-Boutheon, France).