A hormone associated with the beneficial effects of exercise has been found in the blood of exercising humans, this time thanks to more robust methods than those used in past studies.

Bruce Spiegelman and Steven Gygi of Harvard Medical School in Boston, Massachusetts, and their colleagues reported in 2012 that exercise boosted levels of the hormone irisin in the blood of mice and humans. But other researchers branded the finding a myth, saying that the human gene for irisin cannot produce a protein and that the tests used to detect the hormone were flawed. The team has now repeated the experiment with the more precise technique of tandem mass spectrometry, which confirmed the original findings.

The technique is expensive and slow, but could be used to validate higher-throughput tests for irisin as they are developed, the authors say.

Cell Metab. http://doi.org/6s9 (2015)