Some questions about swimming's contribution to fitness

There was a recent study published by Stephen Blair and colleagues that found swimming in men was associated with lower all-cause mortality than being sedentary or walking for exercise. I believe that study by Steven Blair is described here uscnews.sc.edu/.../02022009-HLTH029.html "Swimming cuts men’s risk of dying by about 50 percent compared with running, walking and not exercising, according to a study by Dr. Steven Blair" and published in IJARE, 2(2), May 2008 hk.humankinetics.com/.../bissues.cfm It appears he talked about in a keynote at a conference www.nspf.com/.../BlairKeynote.html That organization (NSPF) apparently helped fund the research, the results of which are again described in nspf.com/.../PR_Blair.pdf "Dr. Blair also found that regular swimmers had a higher cardiorespiratory fitness than walkers and sedentary people." I have not read the full study and my instinct is that the results are too good to be true, but he seems to have excellent credentials. The release indicates the study involved 40,000 athletes and spanned 32 years. But, if mortality difference were true to that extent, I think it would generally have been recognized before any study was done. Without seeing the details, I'd offer these concerns... Are these comparisons (e.g., swimmers vs runners) valid for weekend athletes, health/fitness athletes (non-competitive, 3 workouts a week), and/or competitive athletes, or does it blend them all together (in which case, are the mixtures per sport similar)? How does the study handle the situation of athletes that may quit their sport due to injury or disability/illness? Is there a (unintended) bias due to swimming or walking being prescribed by doctors for health, injury or weight issues? Or a bias due to financial differences (affecting health care options, etc.) in the populations for the different activities? (Please note, I am neither a physician nor trained in public health.)

There was a recent study published by Stephen Blair and colleagues that found swimming in men was associated with lower all-cause mortality than being sedentary or walking for exercise. I believe that study by Steven Blair is described here uscnews.sc.edu/.../02022009-HLTH029.html "Swimming cuts men’s risk of dying by about 50 percent compared with running, walking and not exercising, according to a study by Dr. Steven Blair" and published in IJARE, 2(2), May 2008 hk.humankinetics.com/.../bissues.cfm It appears he talked about in a keynote at a conference www.nspf.com/.../BlairKeynote.html That organization (NSPF) apparently helped fund the research, the results of which are again described in nspf.com/.../PR_Blair.pdf "Dr. Blair also found that regular swimmers had a higher cardiorespiratory fitness than walkers and sedentary people." I have not read the full study and my instinct is that the results are too good to be true, but he seems to have excellent credentials. The release indicates the study involved 40,000 athletes and spanned 32 years. But, if mortality difference were true to that extent, I think it would generally have been recognized before any study was done. Without seeing the details, I'd offer these concerns... Are these comparisons (e.g., swimmers vs runners) valid for weekend athletes, health/fitness athletes (non-competitive, 3 workouts a week), and/or competitive athletes, or does it blend them all together (in which case, are the mixtures per sport similar)? How does the study handle the situation of athletes that may quit their sport due to injury or disability/illness? Is there a (unintended) bias due to swimming or walking being prescribed by doctors for health, injury or weight issues? Or a bias due to financial differences (affecting health care options, etc.) in the populations for the different activities? (Please note, I am neither a physician nor trained in public health.)