Doing certain types of hard arm exercises that lengthen the muscle while it's working can make your arms weaker and less flexible within a day.

Some guys who do really intense bicep exercises can lose almost all their strength right after and take over a month and a half to fully recover — way longer than usual.

After doing a hard arm workout twice, four weeks apart, people feel stronger sooner the second time—even though they did the same amount of work.

When people who don't normally lift weights do a tough arm exercise twice, four weeks apart, their biceps don't stretch as much the second time, even though they're trying just as hard.

People push just as hard during the second workout as the first, even though they feel less sore and recover faster.

Doing a new type of strength exercise that stretches your biceps a lot can cause temporary muscle damage and soreness in women, and these effects can last up to four days.