It is surprising to hear that the first scientific article showing that vigorous exercise could influence certain components of the immune system was way back in 1902.
To show this, R.C. Larrabee took blood from four competitors in the 1901 Boston Marathon both before the race and again within 5 minutes of completion. He found that all began the race with no abnormalities, but that the end tests all showed evidence of leucocytosis (that's a white blood cell count above the normal range in blood to you and me).
With his conclusion stating that a marathon is a "violent, prolonged, exhausting work" and earlier mentioning that "...the winner...covered the distance in less than two and one-half hours. This is about ten miles an hour, about as fast as an ordinary man rides his bicycle for pleasure", perhaps we can conclude that R.C. Larrabee wasn't into his running! (FYI - the 2012 Boston Marathon winner came home in 2 hours 12 minutes.)
The first report linking physical activity and cancer risk dates back to 1922, where it was observed that men involved in physically active occupations experienced lower cancer mortality rates than their fellow men engaged in less strenuous jobs.
Cherry, T. (1922). A theory of cancer. Medical Journal of Australia, 1, 425–438.
Since this report, more than 190 reports from epidemiological studies and over 10 reviews have examined this relationship. This body of evidence is still growing.
Using exercise as therapy goes back even further to 1796, with an early exercise machine superbly called "The Gymnasticon" (see image) invented to 'give and apply motion and exercise, voluntary or involuntary, to the limbs, joints, and muscles of the human body'.
