Came across this old article in the British Journal of Sports Medicine. 18 middle aged people were seperated in to 2 groups. 9 did Soo Bahk Doo, 9 led sedantry lifestyles. They were then submitted to a battery of fitness tests (to test flexibility, strength, co-ordination, aerobic fitness et al).
In case you don't make it to the end I will ruin the surprise and tell you that the SBD students were far better in every test (except grip strength) than the sedantry group. Shocking stuff I know!!!
I decided to share this as although it wasn't a large study, certainly it offered encouraging results. There are have been some folks in the past who have asked if they are too old to start martial arts. I would say this study helps to show that traditional martial arts* probably a WAYYYY healthier option than doing nothing. I know that seems like common sense but you'd be surprised how many people need convincing!http://bjsm.bmj.com/content/38/2/143.abs
* Although this study looked at SBD students, I'd be fairly sure the results would be similar if they looked at students of a similar age group who did karate a similar traditional art.