Purpose: Weight training is a training method that can effectively increase muscle strength and anaerobic exercise capacity. The muscles of the lower extremities, which have been trained through lower body exercises, are a particularly important group of muscles for daily physical and sporting activities. The purpose of this study was to investigate the difference squat loading of the lower extremity joints movement pattern between trained versus un-trained individuals. Method: A total of 20 physically healthy individuals 10 trained subjects(age: 28.71±2.41 yrs, height: 178.92± 4.25 cm, weight: 81.72±4.98 kg) and 10 un-trained subjects(age: 29.42±3.67 yrs, height: 176.62±3.8 cm, weight: 80.2±5.11 kg) participated in this study. The un-trained subjects who had not performed regular resistance exer-cise for at least the past 1 year, and had no experience performing squat movements were selected. The trained group was selected as subjects who had regularly performed resistance strength training for at least 3 years. The three-dimensional motion analysis system, force plate and an wireless electromyography system were synchro-nized and used for measurement. Results: The results of this study showed that there was difference between the trained group and the un-trained group and the trained group showed the pattern of knee varus and un-trained group showed the valgus angle(Knee valgus) displacement. Also, Statistically significant differences appeared in knee forward movement and the trained group(5cm) showed less than the un-trained group(11cm). In the case of MLSI(Medial-Lateral Stability Index), the untrained group showed a higher stability index than the trained group. It was found that the stability index of the trained and untrained groups increased as the body weight increased. Conclusion: The purpose of this study was to investigate the effect of various squat loads on lower extremity movement patterns and stability index during squat exercise between trained and untrained individuals. The subjects of the study were 10 trainees who regularly squat for 3 years and 10 non-trainers who practiced squats irregularly throughout their lives. As a result of the experiment, it was confirmed that the untrained group had greater knee forward movement and a smaller hip flexion angle than the trained group. In the stability index, it was confirmed that the untrained group showed a higher stability index than the trained group. In future studies, it is considered necessary to study the improvement of squat motion in untrained individuals. It is important to check for changes in movement patterns after training.