When I maxed out my bench press, I could lift 150 pounds. However, I only lift a maximum of 60 pound dumbbells however I try. I could not lift 65 pound dumbbells (130 pounds) but I could lift a 150 pound barbell. The movement seems to be the same and the weight is less. Why is a barbell somehow easier to bench?
I believe it comes down to isolation - barbell isolates (given you're using proper form) your chest, shoulders, arms.
With dumbbells or free weights, it takes more effort (more muscles are activated) to perform the same movement because you have more freedom of movement. Also, if one arm is weaker than the other, it's harder to mask that.
More info on those points is linked below, specifically:
- Increases stabilization required & muscle activation
- Helps overcoming strength imbalances
- Increased range of motion