A few weeks ago an active patient of mine asked me a fantastic question that no other patient had asked in my ten years of experience as a PT.
"What is something that your elderly patients aren't doing that they should be doing?"
It wasn't a specific question focused on her in particular, although she could relate to it. She admitted that she was here for 30 minutes and I had a lot of knowledge and she might as well pick my brain a bit.
My answer was STRENGTHENING. Many people as they get older focus on endurance because that is the limitation they are more aware of, they get tired doing things around the house, in the yard, or exercising. They attribute the fatigue to a lack of cardiovascular endurance. This isn't to say that their regular walks and time on the stationary bike or elliptical isn't beneficial but what they are forgetting is people lose muscle mass as they age. The lack of strength can be a major contributor to the fatigue they feel. As they get stronger the perceived effort they put into a given task decreases.
When it comes to strengthening, particularly elderly patients, and even more so with elderly female patients, the strengthening they do is often very low level. Elderly patients gravitate to the itty bitty dumbbells, 1-3 lbs. Now I don't want to knock the little weights because they are completely appropriate for some people but if you're someone who doesn't have an issue picking up a casserole dish off the table or their newborn 8 lb infant you probably need more of a challenge.
You should also take into account the muscles you're working. The primary muscle of the arms are smaller than the legs, the expectation is your legs should be stronger than your arms. If you weigh 150 lbs, every time you stand up from a chair you're moving most of that weight. Getting on a leg press with 20 lbs is probably too conservative. If you can maintain good form without pain, continue to increase the weight until completing 3 sets of 10-15 reps is difficult.
If you have questions on form or setting up a strength training routine, your local physical therapist is a wonderful resource and remember... effort with strength training should be felt in your muscles "the meaty part", not your joints.