1) Climbing up and down stairs - climbing stairs is not advisable for the elderly. It places to much strain on the knee cap. The knee cap is usually the first to wear out and avoiding stairs whenever possible can significantly reduce knee pain
2) Sitting on the floor - while sitting on the floor can recharge your body faster for your next schedule, it is not exactly safe for your knees if you have crossed 50 years of age. Slouching to sit on the floor and getting up from that position can place enormous pressure on the knees and accelerate wear and tear off the joint
3) Squatting on the floor commode - this is the activity that produces the most amount of pressure on the knee joint and under the knee cap. Using a raised commode or just a wooden or plastic augment to the floor commode can go a long way in increasing the life of your knee joint
4) Kneeling on the floor as in cleaning the floor or for prayers places direct pressure on the cartilage of the knee cap and causes damage. It is best avoided when possible in old age or when you have knee pain
5) Running is not a good idea for the elderly. A brisk walk can both keep you fit and also avoid