Toning - definition: the act of lowering body fat, to reveal underlying muscle.
In other words, toning has jack**** to do with your training, number of reps, or weight used. It has EVERYTHING to do with your diet/calorie intake.
granted you DO need to have enough muscle to 'show off' for that chisled look with a low bodyfat percentage...otherwise you just look scrawny.
but all 50 reps with 10lbs does is build endurance. endurance places zero emphasis on growing muscle, or strength...it just builds the ability to do more reps with little weight.
that's why marathon runners don't look like bodybuilders
spend more time with us and we'll help you debunk all the myth's you've heard, and get started on the right way to train.
speaking of which, if you want bigger, defined biceps....ditch all those curls, and start doing more heavy rows and compound back exercises: seated cable rows, pull ups, chin ups, barbell or dumbbell rows, and deadlifts.