I am 73 and had been doing light weights, 8 to 12 reps, 3 to 4 sets for the last 3 years without much gain. I recently switched about 3 months ago to heavy weights, 3 to 5 reps and 5 set and can see a significant improvement in my strength. Also the heavy squats and dead lifts eliminated back and leg pain I had been suffering from for several years.

http://www.dailymail.co.uk/health/ar...s-muscles.html