The first and most common observation new clients are surprised to discover, is their left arm is much weaker than their right.
This is very common. Right handed people don’t have much reason to use their left hand in their daily activities. When they are not regularly working on maintaining strength, their left falls behind.
It’s not just a strength issue. Most of the time it’s very much about endurance as well. When trainees start their training, initially we work toward strength and endurance training with a 12-15 rep goal, always starting with the weaker arm. I’ve noticed most people can lift 1-6 reps with the same weight but then get fatigued much easier on their left side, for all arm exercises.
The good news is this problem corrects itself rather quickly. Once muscles wake up, the strength and endurance catches up within a few weeks. It can be frustrating in the beginning, knowing you can do so much more with your right but once things start to equal out, then strength training becomes more rewarding and enjoyable.
Funny enough, lefties don’t have this problem. In a world made for right handed people, left handed folk have regularly use both right and left for daily activities.