Lee, Chang Woock (2016-05). The Effects of Dietary Choline on Muscle Responses to Resistance Exercise in Older Adults. Doctoral Dissertation. Thesis uri icon

abstract

  • Choline is an essential nutrient for humans. It participates in many important physiological processes including membrane signaling/integrity, neurotransmission, methylation, and lipid transport. Since choline is a precursor to acetylcholine (ACh), a neurotransmitter that mediates muscle contraction, studies have been conducted to examine the relations between choline intake and endurance exercise performance. However, the results were equivocal, mostly due to lack of nutritional control, and there has been no study that examined the effects of choline associated with resistance exercise (RE). The purpose of this research was to investigate the effects of dietary choline on muscle responses to RE in three study populations. It was hypothesized that low choline consumption would negatively influence changes in lean mass and strength in response to RE in older adults. The first study examined the effects of habitual choline intake in the context of commonly recommended "healthy eating", on changes in strength and lean mass following 12 weeks of full body resistance exercise training (RET). The results showed that lower intake of choline (<50% of Adequate Intake [AI]) was associated with significantly diminished gains in strength and lean mass compared with higher choline intakes (~63% or ~85% of AI). The second study investigated the effects of choline supplementation from egg yolk for 12 weeks on muscle responses to RET in a randomized double-blind placebo-controlled trial. The results showed that lower (~51% of AI) choline consumption significantly impaired strength but not muscle gains compared with moderate choline intake (~68% of AI) while higher (~118% of AI) choline intake did not provide additional benefits on strength gains. The third study examined the effects of choline supplementation for 3 weeks on EMG amplitude and strength responses. No choline effect was observed on isometric force outputs, maximum strength on leg press/leg extension, or EMG amplitudes. The results of these studies suggest that only lower choline intake (~50% of AI) for more than one month may negatively affect change in strength associated with RET. Consumption of varying amounts of choline for a short period or higher than recommended amounts of choline may not influence muscle responses to RE.
  • Choline is an essential nutrient for humans. It participates in many important physiological processes including membrane signaling/integrity, neurotransmission, methylation, and lipid transport. Since choline is a precursor to acetylcholine (ACh), a neurotransmitter that mediates muscle contraction, studies have been conducted to examine the relations between choline intake and endurance exercise performance. However, the results were equivocal, mostly due to lack of nutritional control, and there has been no study that examined the effects of choline associated with resistance exercise (RE).
    The purpose of this research was to investigate the effects of dietary choline on muscle responses to RE in three study populations. It was hypothesized that low choline consumption would negatively influence changes in lean mass and strength in response to RE in older adults.
    The first study examined the effects of habitual choline intake in the context of commonly recommended "healthy eating", on changes in strength and lean mass following 12 weeks of full body resistance exercise training (RET). The results showed that lower intake of choline (<50% of Adequate Intake [AI]) was associated with significantly diminished gains in strength and lean mass compared with higher choline intakes (~63% or ~85% of AI).
    The second study investigated the effects of choline supplementation from egg yolk for 12 weeks on muscle responses to RET in a randomized double-blind placebo-controlled trial. The results showed that lower (~51% of AI) choline consumption significantly impaired strength but not muscle gains compared with moderate choline intake (~68% of AI) while higher (~118% of AI) choline intake did not provide additional benefits on strength gains.
    The third study examined the effects of choline supplementation for 3 weeks on EMG amplitude and strength responses. No choline effect was observed on isometric force outputs, maximum strength on leg press/leg extension, or EMG amplitudes.
    The results of these studies suggest that only lower choline intake (~50% of AI) for more than one month may negatively affect change in strength associated with RET. Consumption of varying amounts of choline for a short period or higher than recommended amounts of choline may not influence muscle responses to RE.

publication date

  • May 2016