Effects of L-arginine and L-citrulline Supplementation on Muscle Respiration
- Conditions
- Dietary Exposure
- Interventions
- Dietary Supplement: Dietary SupplementBehavioral: Endurance exercise on a cycle ergometer
- Registration Number
- NCT03998800
- Lead Sponsor
- Loughborough University
- Brief Summary
The objective of this trial is to determine the effects of dietary supplementation with the amino acids, L-arginine and L-citrulline, on endurance performance and mitochondrial respiration in healthy men compared to supplementation with L-arginine alone and a placebo supplement.
- Detailed Description
This study is a randomized, double-blind, cross over trial of L-arginine and L-citrulline supplementation, L-arginine supplementation alone and placebo supplementation in healthy men. The intervention period will be 8-11 weeks for each participant and a minimum of 15 individuals will be recruited and enrolled to complete the trial. Subjects will complete the experimental protocol described below over 3 individual 10 day supplementation periods, separated by washout periods of approximately 2 weeks. Subjects will ingest corn-starch as a placebo, L-arginine (3g/day) or L-arginine (1.5 g/day) + L-citrulline (1.5g/day). On day 7 of the supplementation period, a skeletal muscle biopsy and blood sample will be obtained from the subjects to investigate mitochondrial function and blood amino acid and nitric oxide levels. On day 10 of the supplementation period, subjects will complete a performance test on a cycle ergometer to investigate their endurance performance. These assessments will be performed to determine the effects of co-ingesting L-arginine and L-citrulline compared to L-arginine alone and placebo administration.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- Male
- Target Recruitment
- 18
- healthy male, 18-40 years of age
- recreationally-active
- healthy BMI (≥18.5 and ≤24.9 kg/m2)
- participating in other studies currently or in the past two months or has an intention to participate in other studies over the period of this study
- history of gastric, digestive, cardiovascular, renal disease or any other orthopaedic diseases related to motor organs
- lidocaine allergy
- use of medication that may affect study measures
- contraindication to the biopsy procedures
- on medications that affect the immune system
- on Aspirin or other drugs known to prolong bleeding
- smoker
- user of dietary supplements currently or in the past one month
- a heavy drinker
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description L-arginine Dietary Supplement 10 days of supplementation with 3 g of L-arginine per day L-arginine Endurance exercise on a cycle ergometer 10 days of supplementation with 3 g of L-arginine per day L-arginine and L-citrulline Endurance exercise on a cycle ergometer 10 days of supplementation with 1.5 g of L-arginine and 1.5 g of L-citrulline per day Placebo (corn-starch) Endurance exercise on a cycle ergometer 10 days of supplementation with corn-starch Placebo (corn-starch) Dietary Supplement 10 days of supplementation with corn-starch L-arginine and L-citrulline Dietary Supplement 10 days of supplementation with 1.5 g of L-arginine and 1.5 g of L-citrulline per day
- Primary Outcome Measures
Name Time Method Change in Endurance performance on a cycle ergometer between L-arginine supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation periods, subjects will complete a performance test on a cycle ergometer to investigate their endurance performance
Changes of mitochondrial function in skeletal muscle between L-arginine supplementation and placebo supplementation 8-11 weeks On day 7 of the supplementation periods, a skeletal muscle biopsy sample will be obtained from subjects to investigate mitochondrial function.
Changes of mitochondrial function in skeletal muscle between L-arginine + L-citrulline supplementation and placebo supplementation 8-11 weeks On day 7 of the supplementation periods, a skeletal muscle biopsy sample will be obtained from subjects to investigate mitochondrial function.
Change in Endurance performance on a cycle ergometer between L-arginine + L-citrulline supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation periods, subjects will complete a performance test on a cycle ergometer to investigate their endurance performance
- Secondary Outcome Measures
Name Time Method Changes in muscle oxygenation between L-arginine + L-citrulline supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation periods, skeletal muscle oxygenation will be assessed using near-infrared spectroscopy to reveal the tissue saturation index during exercise.
Changes of amino acid and nitric oxide biomarkers levels in plasma between L-arginine supplementation and placebo supplementation 8-11 weeks On days 7 and 10 of the supplementation periods, a venous blood sample will be obtained from subjects to investigate amino acid and nitric oxide biomarkers levels in plasma.
Changes in subjective feeling during and after exercise between L-arginine + L-citrulline supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation period, subjective feeling during (using the 6-20 ratings of perceived exertion scale) and after (using a 100 mm visual analogue scale where 0 mm = no pain and 100 m = maximal pain) exercise will be assessed. Subjective feeling will also be assessed on the morning of day 11 of each supplementation period.
Changes in subjective feeling during and after exercise between L-arginine supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation period, subjective feeling during (using the 6-20 ratings of perceived exertion scale) and after (using a 100 mm visual analogue scale where 0 mm = no pain and 100 m = maximal pain) exercise will be assessed. Subjective feeling will also be assessed on the morning of day 11 of each supplementation period.
Changes in muscle oxygenation between L-arginine supplementation and placebo supplementation 8-11 weeks On day 10 of the supplementation periods, skeletal muscle oxygenation will be assessed using near-infrared spectroscopy to reveal the tissue saturation index during exercise.
Changes of amino acid and nitric oxide biomarkers levels in plasma between L-arginine + L-citrulline supplementation and placebo supplementation 8-11 weeks On days 7 and 10 of the supplementation periods, a venous blood sample will be obtained from subjects to investigate amino acid and nitric oxide biomarkers levels in plasma.
Trial Locations
- Locations (1)
School of Sport, Exercise and Health Sciences
🇬🇧Loughborough, Leicester, United Kingdom