The researchers exercised 11 young men to exhaustion over about 70 minutes, then massaged a single leg (determined randomly for each man) for ten minutes. The subjects received a muscle biopsy in both quad muscles to gather samples for massaged and non-massaged legs. The biopsy was repeated after a 2.5-hour rest period.
Researchers analyzed the samples from the different legs to see what was going on after the massage. They found two major changes: reduced signs of inflammation, and an increase in production of mitochondria, the cell's energy factories.
Curbed production of inflammatory molecules "may reduce pain by the same mechanism as conventional anti-inflammatory drugs" like aspirin and ibuprofen, the authors write.
The increase in mitochondria might also aid in recovery, the researchers speculate. This means that massage joins a few other alternative therapies in the category of "it works, but we're not sure why." Still, it's useful to know that massage causes a measurable physiological reaction.