PURPOSE: The micronutrient choline plays a major role in neurotransmission and skeletal muscle contraction. We conducted a randomized controlled trial to examine the effects of choline intake on skeletal muscle responses to resistance exercise training (RET) in older adults.
METHODS: Three groups of 50 to 69-year-old generally healthy men and women (n=37, age=59.8 ± 6 y, height=168.4 ± 9 cm, weight=79.5 ± 16 kg, body fat=30.3 ± 10 kg, male/female=15/22) underwent 12 weeks of RET (3x/week, 3 sets, 8-12 reps, 70% of maximum strength [1RM]) and submitted >1,776 diet logs (>4x/week for 12 weeks, 37 subjects). Participants’ diets (mean choline intake: 5.9 mg/kg lean/d) were supplemented with 0.7 mg/kg lean/d (Low, n=13), 2.8 mg/kg lean/d (Med, n=11), or 7.5 mg/kg lean/d (High, n=13) of choline in the form of egg yolk. Body composition, 1RM, and blood tests were performed before and after training.
RESULTS: ANCOVA tests showed Low choline intake, compared with Med or High choline intakes, resulted in significantly diminished gains in composite strength (leg press + chest press 1RM; Low: 19.4 ± 8.2%, Med: 46.8 ± 8.9%, High: 47.4 ± 8.1%, p=0.034) and thigh muscle quality (leg press 1RM / thigh lean mass; Low: 12.3 ± 9.6%, Med/ High: 46.4 ± 7.0%, p=0.010) after controlling for lean mass, protein, betaine, and vitamin B12. No differences were observed in lean mass gains, clinical markers of liver/muscle damage, or blood lipid profiles.
CONCLUSION: These data indicate that low supplemental choline intake negatively affects strength gains with RET in older adults. This study was supported by U.S. Poultry and Egg Association.