If your goal is to gain more lean muscle on your frame - and avoid getting hurt in the process - than stop training like a powerlifter!
While doing heavy low rep sets can help you build strength, it's a double edge sword because it also increases your risk of injury. And there's nothing that will slow your progress down more than getting injured!
If building a lean muscular physique is your #1 objective, you need to perform a higher volume of repetitions to stimulate hypertrophy.
This is especially true if you're not a young buck anymore and you're over the age of 40.
What's the BEST Rep Range for Building Lean Muscle?
Well a lot of the old school bodybuilders used to do high reps - as many as 15 to 20 reps and even higher - to pack on lean mass.
So leave the ego at the gym door, lighten the weight, increase the reps, and train with more time under tension to help spur on new growth - while reducing your risk of injury, aches, and pains in the process
If you'd like to see an example of how to perform this style of training for yourself - then check out my Beginner Muscle Building Workout that I posted up on YouTube. 
