With your hands.
By doing excersizes with dumbbells that work-out your biceps. E.G-Bicep curls.
you need biceps to react with triceps in your arm and biceps help you lift things
A muscle fiber gets a signal to move from a nerve and then it moves!
Dumbbells work a variety of muscles. They work the biceps, triceps, deltoids, shoulders, chest, back. You can also use them when doing lunges for a bigger workout.
There are good exercises you can do for biceps .They also say swimming the beast stroke is good for building biceps. Here is a site or two on biceps www.bodybuilding.com/fun/weik2.htm , and this site www.bodybuilding.com/fun/brewster11.htm
biceps
It is harder to lift two 25 pound dumbbells because you have to balance the dumbbells. So it takes more effort, and uses more muscles to help keep the weights balanced.
Dumbbells feel heavier than barbells because the weight is distributed differently. With dumbbells, the weight is spread out in each hand, making it feel more challenging to lift compared to a barbell where the weight is centralized.
Pectoral Muscles, Biceps, and Triceps.
Dumbbells are harder to lift than barbells because they require more stabilization and coordination from your muscles since each arm is working independently. This makes the exercise more challenging and can lead to greater muscle engagement and strength gains.
hold 1 dumbbell in each hand. lay flat on your back, and with your arms to the side, like a T, slowly lift them up. hold them 1 foot off the ground for 10 secs, and lower. do 20 of them whenever you think about it and your muscles will blow through the roof.
Theses are the muscles who works with a dumbbells: Primary Movers: Anterior Deltoid Secondary Movers Lateral Deltoid Supraspinatus Triceps Brachii (the triceps is actually only a two headed muscle) Middle Trapezius Pectoralis Major Stabilizers: Long head of the triceps Short head of biceps brachii (funnily enough the biceps is a three headed muscle) Upper trapezius