Effects of dietary protein on enzyme activity following exercise-induced muscle injury.
OBJECTIVE
The objective of this investigation was to determine the effects of varying levels of dietary protein on the postexercise increase in serum and muscle enzyme activity normally observed following exercise-induced muscle injury.


METHODS
Serum creatine kinase (CK), serum aspartate aminotransferase (AST), and muscle glucose-6-phosphate dehydrogenase (G-6-PD) activities were measured in rats fed for 10 d on high (50%), normal (12%), or low (4%) protein diets following a single bout of eccentric exercise (treadmill running at 16 m.min(-1), -16 degrees incline, 90 min).


RESULTS
The exercise intervention resulted in significant increases in serum CK and AST activities in all diet groups. Serum CK demonstrated peak activity immediately postexercise with increases reaching 910+/-94, 594+/-53, and 283+/-52 IU.L(-1) for animals on high, normal, and low protein diets, respectively. Similarly, peak postexercise AST activity for high, normal, and low protein diets reached 193+/-10, 147+/-3, and 162+/-9 IU.L(-1), respectively. The exercise intervention resulted in increases in muscle G-6-PD activity for all diet groups; however, LP rats demonstrated significantly lower values than NP or HP rats.


CONCLUSIONS
These data show that dietary protein intake can significantly effect both serum and muscle enzyme activity following acute exercise-induced muscle injury.
Hayward
R
R
Department of Kinesiology, University of Northern Colorado, Greeley 80639, USA.
Ferrington
D A
DA
Kochanowski
L A
LA
Miller
L M
LM
Jaworsky
G M
GM
Schneider
C M
CM
D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001835:Body Weight; D004044:Dietary Proteins / Q000494:pharmacology*; D005069:Evaluation Studies as Topic; D005953:Glycogen Storage Disease Type I / Q000097:blood; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D004044:Dietary Proteins; D001219:Aspartate Aminotransferases