Moderately Increased Protein Intake Predominately From Egg Sources Does Not Influence Whole Body, Regional, or Muscle Composition Responses to Resistance Training in Older People

J Nutr Health Aging. 2009 Feb;13(2):108-14. doi: 10.1007/s12603-009-0016-y.

Abstract

The effects of increased dietary protein on resistance training (RT)-induced changes in body composition and skeletal muscle fiber size are uncertain in older people.

Objectives: We hypothesized that the ingestion of more animal-based foods, especially eggs, to achieve a higher protein intake would enhance RT-induced changes in body composition.

Setting: West Lafayette, IN.

Participants: 36 older people (age 61 +/- 1 y; mean +/- SEM).

Intervention: Subjects completed RT three d/wk for 12 weeks, and consumed omnivorous diets that contained either 0.9 +/- 0.1 (lower protein) or 1.2 +/- 0.0 (higher protein) g protein x kg(-1) x d(-1) (12 +/- 3 and 17 +/- 5% of energy intakes, respectively), with the higher protein intake achieved by consuming more eggs, meats, and dairy foods. The lower and higher protein diets contained 213 +/- 21 and 610 +/- 105 mg cholesterol/d, respectively.

Measurements: Strength, body composition, serum lipid-lipoprotein profile, urinary creatinine, skeletal muscle fiber type and size.

Results: Among all subjects, over time (i.e. with RT) body weight was unchanged, lean mass (1.1 +/- 0.2 kg) increased, and fat mass (-1.4 +/- 0.2 kg) decreased (all changes P < 0.05). Regional (i.e. trunk, legs, arms) lean mass increased and fat mass decreased. Whole body muscle mass (24-h urinary creatinine excretion) increased, but skeletal muscle (vastus lateralis) type 1, type 2a, and type 2x fiber cross-sectional areas did not change from baseline. Serum total and LDL cholesterol decreased (P < 0.05) and HDL cholesterol and triacylglycerol were unchanged. Dietary protein and cholesterol intakes did not influence these responses to RT.

Conclusion: Consumption of diets that contained moderately higher protein and variable amounts of cholesterol did not differentially affect body composition, skeletal muscle fiber size, or serum lipid-lipoprotein profile responses to resistance training in older people.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adiposity / drug effects
  • Aged
  • Aged, 80 and over
  • Aging / physiology*
  • Body Composition / drug effects*
  • Body Composition / physiology
  • Cholesterol / blood
  • Cholesterol, Dietary / pharmacology
  • Creatinine / urine
  • Dairy Products
  • Diet
  • Dietary Proteins / pharmacology
  • Dietary Proteins / therapeutic use*
  • Dose-Response Relationship, Drug
  • Eggs*
  • Energy Intake
  • Female
  • Humans
  • Indiana
  • Male
  • Meat
  • Middle Aged
  • Muscle Weakness / diet therapy
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / physiology
  • Resistance Training*
  • Weight Lifting / physiology*

Substances

  • Cholesterol, Dietary
  • Dietary Proteins
  • Cholesterol
  • Creatinine