Your biceps and triceps -- the muscles of your upper arm -- work to bend and straighten your arm and turn your wrist. Your upper-arm muscles function in a variety of athletic activities. Rope climbing and arm wrestling heavily tax your biceps, and your triceps function in everything from pushing to punching. Consult a health care practitioner before starting any exercise program.
Triceps
Your triceps -- the muscles on the back of your upper arm -- extend your elbow. Every time your arm straightens against resistance, you are using your triceps. Any exercise where your elbow extends, such as pushdowns, barbell extensions or overhead extensions allows you to focus on your triceps. Compound exercises that use multiple joints, including the bench press, heavily work your triceps, according to a 1995 study published in the "Journal of Strength and Conditioning Research." The effort of pushing your arms straight against the resistance of the bench press causes significant elbow extension and triceps recruitment.
Biceps
Your biceps serve two purposes -- flexing your elbow and suppinating your wrist. Flexion of the elbow occurs when you bend your arm up, and takes place in exercises such as barbell curls. Suppination is when you turn your palm so it faces up, and occurs in exercises such as dumbbell curls, where you rotate your wrist on the way up to activate this function of your biceps. Compound exercises such as chinups and barbell rows heavily tax your biceps, as your elbow is flexing while your biceps is in a stretched position.
How They Function
Muscle fibers, small units of contractile tissue, comprise the bulk of all skeletal muscles, including your biceps and triceps. Muscle fibers vary in size and get recruited on an as-needed basis. When placed under stress, your muscle fibers contract. The greater the stress, the greater the contraction. Muscle fibers are recruited in order of size, with smaller fibers being recruited first. So if you truly want results, you need to train with heavy weights to develop the larger, stronger muscle fibers. Light weights with high repetitions will do little to build strength or muscle.
Efficiency
The ability of your muscles to accomplish a task -- generate power -- is based on two functions, size and recruitment. The limit strength of a muscle is determined by its peak cross-sectional area, or the area of your muscle at its widest point. The number of fibers you can recruit and the rate at which you recruit them plays a key role in strength, which is why strength athletes lift extremely heavy weights and display more efficient recruitment of large muscle fibers.
References
- "Journal of Strength and Conditioning Research"; Effects of Variations of the Bench Press Exercise on the EMG Activity of Five Shoulder Muscles; Chris Barnett, et al.; November 1995
- "Strength Training Anatomy - Third Edition"; Frederic Delavier; 2010
- "Physiology of Sport and Exercise, Fourth Edition"; Dr. Jack H. Wilmore; 2007
- "Science and Practice of Strength Training, Second Edition"; Vladimir Zatsiorsky, et al.; 2006
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