Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters.
BACKGROUND
Acute consumption of fat-free fluid milk after resistance exercise promotes a greater positive protein balance than does soy protein.


OBJECTIVE
We aimed to determine the long-term consequences of milk or soy protein or equivalent energy consumption on training-induced lean mass accretion.


METHODS
We recruited 56 healthy young men who trained 5 d/wk for 12 wk on a rotating split-body resistance exercise program in a parallel 3-group longitudinal design. Subjects were randomly assigned to consume drinks immediately and again 1 h after exercise: fat-free milk (Milk; n = 18); fat-free soy protein (Soy; n = 19) that was isoenergetic, isonitrogenous, and macronutrient ratio matched to Milk; or maltodextrin that was isoenergetic with Milk and Soy (control group; n = 19).


RESULTS
Muscle fiber size, maximal strength, and body composition by dual-energy X-ray absorptiometry (DXA) were measured before and after training. No between-group differences were seen in strength. Type II muscle fiber area increased in all groups with training, but with greater increases in the Milk group than in both the Soy and control groups (P < 0.05). Type I muscle fiber area increased after training only in the Milk and Soy groups, with the increase in the Milk group being greater than that in the control group (P < 0.05). DXA-measured fat- and bone-free mass increased in all groups, with a greater increase in the Milk group than in both the Soy and control groups (P < 0.05).


CONCLUSIONS
We conclude that chronic postexercise consumption of milk promotes greater hypertrophy during the early stages of resistance training in novice weightlifters when compared with isoenergetic soy or carbohydrate consumption.
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
Joseph W
JW
Hartman
Jason E
JE
Tang
Sarah B
SB
Wilkinson
Mark A
MA
Tarnopolsky
Randa L
RL
Lawrence
Amy V
AV
Fullerton
Stuart M
SM
Phillips
D000293:Adolescent; D000818:Animals; D001706:Biopsy; D015992:Body Mass Index; D001835:Body Weight; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004041:Dietary Fats; D004734:Energy Metabolism; D015444:Exercise; D006801:Humans; D008892:Milk; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology; D012016:Reference Values; D030262:Soybean Proteins; D011795:Surveys and Questionnaires; D014891:Weight Lifting / Q000502:physiology*
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D030262:Soybean Proteins