You’ve recently experienced some of the most intense arm training workouts ever. You can sense new growth is at hand by the outrageous pump you get when you train arms. You feel the burn down to the bone with each succeeding set. Your diet and rest are balanced, creating the ideal anabolic environment to support new muscle growth. In short, you’re on an arm-training roll; you’ve hit the sweet spot of arm training. What can possibly go wrong now?
In rare instances you may find that not only aren’t you growing, but the muscle appears to be shrinking’or to put it more scientifically, atrophying’as well. How can that be? A case study of a football player who experienced that sorry situation recently appeared in a medical journal.1 What happens is that you suffer a nerve impingement in your upper arm that effectively cuts off nerve stimulation to the biceps muscle, and without that stimulation the muscle shrinks.
Atrophy most often happens to just one arm at a time, but it occurred in both of the football player’s arms. Known as bilateral musculocutaneous nerve palsy, it usually results from excessive training.
What happens next is a selective hypertrophy, or growth, of the brachioradialis muscle, a smaller muscle of the upper arm. When the brachioradialis grows out of balance with the larger biceps, it impinges on the relevant nerves, leading to selective atrophy and biceps weakness. The condition may also be caused by a traction injury to the upper arm from simply training the muscle too hard or subjecting it to unaccustomed exercise.
The football player first noticed something was wrong when his biceps suddenly began to shrink. Although he felt no pain in his arm, he couldn’t even flex his biceps. That followed a routine in which he trained his arms every day for three weeks. After a while he noticed a loss of strength in biceps and in chinning exercises, which involve the biceps.
Diagnosed with biceps nerve impingement in both arms, he was given a training program that eliminated all biceps exercises. A gradual improvement in biceps strength ensued, and after four months his upper-arm nerve conduction returned to normal.
Cases of nerve impingement have been reported in men who trained their biceps with high intensity. That doesn’t mean you should avoid training your arms hard, but you should heed body signals and not overtrain. You must also learn to differentiate normal from pathological pain. In short, if you suspect that any pain you feel during the workout isn’t from the usual burning sensation after a hard set, stop right there. Going any further or simply ignoring the pain may result in atrophy.
Forget the garbage you read in magazines and books about doing endless sets. Trust me, most of that stuff is sheer nonsense, a creature more of the writer’s imagination than of actuality. Learn to listen to your body cues. Common sense equals uncommon muscular gains. IM
1 Matz, S.G., et al. (2004). Bilateral musculocutaneous nerve palsy from strength training. Phys Sports Med. 32:18-20.