hi i have a question that needs answering!

how come i only feel my muscles contract whenever i use light weights to do Bent Over Barbell Rows or side lateral raises and when i use heavy weight to do the same amount of reps (just to experiment), i do not feel the same contraction as i would with light weights!

i feel the same thing for other exercises as well

Possibly you are loading too heavy and forcing some other muscles to take over to cheat up the weight? Focus on the quality, not the quantity, of the exercise!

Jermey