Abstract: The cross-sectional areas of trunk and lower limb muscle groups, psoas major muscle groups, back muscle groups, beta scapular muscle groups, and left upper limb muscle groups in rats administered with casein non-phosphopeptide (CNPP), a byproduct of the production of casein phosphopeptide (CPP) were determined using a transverse spiral computed tomography (CT) scanner. The results showed that the cross-sectional areas of trunk and lower limb muscle groups, back muscle groups, beta scapular muscle groups, and left upper limb muscle groups from no exercise (NE) rats administered with moderate-dose CNPP were significantly 1.19, 1.16, 1.24 and 1.93 times greater than those of the blank group on day 50, respectively (P < 0.05). The increases in the cross-sectional areas of trunk and lower limb muscle groups, back muscle groups of resistance exercise (RE) rats after administration of high-dose CNPP were significantly higher than those of NE rats (P < 0.05), and also significantly higher than those of RE rats administered with lactalbumin at the same dose (P < 0.05). These findings have demonstrated that a combination of physical exercise and dietary supplementation with CNPP can synergistically improve muscle mass in rats.

Key words: casein non-phosphopeptide, resistance exercise, rats, muscle mass