Gym exercise and outdoor exercise, although both aerobic exercise, are limited in gym exercise. It can only be some strength-based sports. Like a treadmill. Pedal bike Weight lifting barbells for arm exercises. Lumbar back abdominal muscle exercise. But outdoor is different. You can breathe the fresh air of nature while doing aerobic exercise. Outdoor sports can do some endurance sports. Such as mountain climbing and swimming. And rock climbing. If the weather is fine, it is recommended to do more outdoor aerobic exercise, which is of great help to physical and mental pleasure. Old people and children can get more sunshine when they exercise outdoors, which is helpful for calcium absorption.