Gabe Mirkin, M.D.
Second wind means that when you run very fast, you
reach a point where you gasp for breath, slow down but keep on
pushing and after a few seconds, you feel recovered and pick up
the pace. Some people think that you just slow down and allow
yourself enough time to recover from your oxygen debt, but
research from the University of California in Berkeley may give
another explanation.
When you run fast, your muscles use large amounts of
oxygen to burn carbohydrate, fat and protein for energy. If you
run so fast that your lungs cannot supply all the oxygen that you
need, you develop an oxygen debt that causes lactic acid to
accumulate in your muscles to make them burn, and you gasp
for air. The muscle burning and shortness of breath caused by
the accumulation of lactic acid forces you to slow down. This
research shows that the lactic acid that accumulates in muscles
when you run very fast actually is the first choice of fuel for your
muscles when you are running so fast that you can't get all the
oxygen that you need (American Journal of Physiology-
Endocrinology and Metabolism, June 2006). So your muscles
switch to burning more lactic acid for energy, you need less
oxygen and then you pick up the pace. Of course when you
keep on pushing the pace, you can again accumulate large
amounts of lactic acid in muscles, which makes them burn and
hurt again.
September 15, 2006