###Human: There is a hike in heart rate and weakness in legs after a walk. Why? ###Assistant: Hi. It seems that you do not have stamina and endurance. Your muscles get tired due to the lack of stretch exercise. You need to start stretch exercise and cardio to gain more energy and endurance. I have gone through the attachment (attachment removed to protect patient identity). With normal investigations, your heart is working regularly. Your body muscles are causing the problem. It is mandatory for you to do body stretching exercise and cardio exercise on a daily basis.