Figure 2: Effects of exercise protocols performed in different intensities on the AMPK and ACC phosphorylation and SIRT-1   and PGC-1α protein levels in the quadriceps of young and middle-aged rats. Phosphorylation of the AMPK (a) and ACC (b) and protein levels of SIRT-1 (c) and PGC-1α (d). Upper panels show representative blots of these proteins. Lower panels show representative blots of total AMPK (a) and total ACC (b) protein levels. The results of scanning densitometry are expressed as arbitrary units. Bars represent means ± SEM of six rats. versus young NE rats, versus middle-aged NE rats, versus young rats at , and versus middle-aged rats at .