One of the most important arm muscles is the triceps brachii (the triceps, for short). You use your triceps to extend your arm. It opposes the biceps muscle, which is used to flex the arm. You also ...

Good things always come in threes: fairy godmothers, parts of a combo meal, boy bands made of brothers (Hi Jonas and Hansen!). So it’s no surprise the most eye-popping muscle in your arms is, in fact, ...

Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. Arm day can be one of ...

Training your triceps helps tone your arms, making them stronger and more defined. Strong triceps support your upper body during everyday movements and improve your ability to push and lift. Adding ...

As the old adage goes, good things always come in threes, so it’s no surprise the most eye-popping muscle in your arms is, in fact, three parts that join together. 'There are three heads to the tricep ...

Dr. Shields is a physical therapist with a background in English Literature and a passion for healthcare and education. She hopes to combine her clinical expertise with her love of writing, establish ...