RT Journal
A1 Stephenson J
T1 EXercise and antioxidants
JF JAMA
JO JAMA
YR 2009
FD June 17
VO 301
IS 23
SP 2432
OP 2432
DO 10.1001/jama.2009.820
UL http://dx.doi.org/10.1001/jama.2009.820
AB 
Exercise improves sensitivity to insulin. But when muscle cells metabolize glucose, “free radicals”—reactive oxygen species (ROS), which can cause cell damage—are produced. However, the researchers reasoned, because reduced mitochondrial metabolism has been linked with type 2 diabetes, ROS generated by exercise also may have a health-promoting effect that antioxidants such as vitamin C or E might undermine.