Creatine-dextrose and protein-dextrose induce similar strength gains during training.
BACKGROUND
Creatine supplementation during resistance exercise training has been reported to induce greater increases in fat-free mass (FFM), muscle fiber area, and strength when compared with a placebo. We have recently shown that timing of nutrient delivery in the postexercise period can have positive effects on whole body protein turnover (B. D. Roy et al., Med Sci Sports Exerc. 32(8):1412-1418, 2000).


OBJECTIVE
We tested the hypothesis that a postexercise protein-carbohydrate supplement would result in similar increases in FFM, muscle fiber area, and strength as compared with creatine monohydrate (CM), during a supervised 2-month resistance exercise training program in untrained men.


METHODS
Young healthy male subjects were randomized to receive either CM and glucose (N = 11; CM 10 g + glucose 75 g [CR-CHO] (CELL-Tech)) or protein and glucose (N = 8; casein 10 g + glucose 75 g [PRO+CHO]), using double-blinded allocation. Participants performed 8 wk of whole body split-routine straight set weight training, 1 h.d(-1), 6 d.wk(-1). Measurements, pre- and post-training were made of fat-free mass (FFM; DEXA), total body mass, muscle fiber area, isokinetic knee extension strength (45 and 240 degrees.s(-1)), and 1 repetition maximal (1RM) strength for 16 weight training exercises.


RESULTS
Total body mass increased more for CR-CHO (+4.3 kg, 5.4%) as compared with PRO-CHO (+1.9 kg, 2.4%) (P < 0.05 for interaction) and FFM increased after training (P < 0.01) but was not significantly different between the groups (CR-CHO = +4.0 kg, 6.4%; PRO-CHO = +2.6 kg, 4.1%) (P = 0.11 for interaction). Muscle fiber area increased similarly after training for both groups (approximately 20%; P < 0.05). Training resulted in an increase in 1RM for each of the 16 activities (range = 14.2-39.9%) (P < 0.001), isokinetic knee extension torque (P < 0.01), with no treatment effects upon any of the variables.


CONCLUSIONS
We concluded that postexercise supplementation with PRO-CHO resulted in similar increases in strength after a resistance exercise training program as compared with CR-CHO. However, the greater gains in total mass for the CR-CHO group may have implications for sport-specific performance.
Tarnopolsky
M A
MA
Department of Medicine (Neurology and Neurological Rehabilitation), Rm. 4U4, McMaster University Medical Center, 1200 Main Street W., Hamilton, Ontario, Canada, L8N 3Z5. tarnopol@mcmaster.ca
Parise
G
G
Yardley
N J
NJ
Ballantyne
C S
CS
Olatinji
S
S
Phillips
S M
SM
D000328:Adult; D000886:Anthropometry; D001219:Aspartate Aminotransferases / Q000097:blood; D001806:Blood Urea Nitrogen; D001835:Body Weight; D003401:Creatine / Q000032:analysis / Q000494:pharmacology*; D003402:Creatine Kinase / Q000097:blood; D003404:Creatinine / Q000652:urine; D004044:Dietary Proteins / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D010806:Physical Education and Training / Q000379:methods
D004044:Dietary Proteins; D003404:Creatinine; D001219:Aspartate Aminotransferases; D003402:Creatine Kinase; D005947:Glucose; D003401:Creatine