
Carl K. answered 01/12/20
Assistant Professor of Family Medicine
Due to knee pain, she will want to choose something that is easy on the knee. Running and jumping, such as playing basketball would cause knee pain and would not be a reasonable choice.
Activities that are easy on the knee are swimming and level walking (not trail hiking on uneven surfaces).
Walking burns about 1 calories per mile per 2 pounds of body weight. Let's say she weighs 120 pounds, then she would burn 65 calories per mile.
She could wear a fitness meter and calories would be 100 calories per 2,000 steps.
Swimming is far more efficient in calories per hour - moderate lap swimming is about 350 calories per 30 minutes.
Swimming is more aerobic than simple step counting, so I would suggest it as the best exercise that is easy on the knee, will burn calories and provide overall fitness improvement. Swimming will use all of her muscles, and provide her with the best alternative for improving body composition.
You would also recommend a diet low in carbs and processed foods, increase vegetables, salads, and food made from scratch.