UCLA Magnesium Formulation Athlete Study

Magnesium is involved in neuromuscular signaling, cellular energy metabolism, autonomic regulation, and sleep-related physiology. Competitive athletes often experience sleep restriction, training stress, travel, soreness, and recovery demands. Magnesium glycinate and magnesium L-threonate are commonly used athlete-facing magnesium formulations, but they are not interchangeable. Glycinate is commonly positioned as a well-tolerated sleep-oriented formulation, whereas L-threonate is of interest because of prior signals related to sleep, cognition, reaction performance, and central nervous system magnesium biology. This single-site UCLA study will enroll adult varsity athletes aged 18 to 35 years. Participants will complete screening, informed consent, baseline assessments, wearable monitoring, a baseline monitoring period, randomization in a 1:1:1 ratio, 4 weeks of blinded nightly capsules, brief daily REDCap morning surveys, weekly adherence and safety check-ins, and final performance-adjacent testing. The primary outcome is change in average WHOOP-derived sleep efficiency from baseline week to final treatment week. Prespecified primary contrasts will compare magnesium glycinate versus placebo and magnesium L-threonate versus placebo. Total sleep time, sleep consistency, resting heart rate, heart rate variability, WHOOP Recovery Score, reaction-time performance, grip strength, countermovement jump height, adherence, tolerability, and adverse events will be analyzed as secondary or exploratory outcomes according to the final statistical analysis plan. The magnesium glycinate versus magnesium L-threonate contrast will be treated as exploratory unless the final statistical analysis plan preserves alpha for that comparison.

• Magnesium glycinate (Dietary supplement): Blinded oral magnesium glycinate, exactly two capsules nightly for 28 days. The nightly dose is 240 mg elemental magnesium by label claim (120 mg per capsule) and 288 mg by lot-specific assay (144 mg per capsule). Take approximately 1 hour before intended bedtime, with food, while upright, and with at least 8 oz water. No study product is taken during the 1-week baseline period.
• Magnesium L-threonate (Dietary supplement): Blinded oral magnesium L-threonate (Magtein), exactly two 1-g capsules nightly for 28 days, for 2 g Magtein and 156 mg elemental magnesium nightly based on the linked raw-ingredient assay of 7.8% magnesium. Take approximately 1 hour before intended bedtime, with food, while upright, and with at least 8 oz water. No study product is taken during the 1-week baseline period.
• Placebo (Other): Matched oral placebo, exactly two capsules nightly for 28 days. Each capsule contains calcium laurate 300 mg plus silicified microcrystalline cellulose 440 mg and no active magnesium. Take approximately 1 hour before intended bedtime, with food, while upright, and with at least 8 oz water. No study product is taken during the 1-week baseline period. One matched-placebo regimen is used, without double-dummy.

Primary outcomes

• Change in WHOOP-derived sleep efficiency percentage from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: Average nightly WHOOP-derived sleep efficiency, expressed as a percentage, will be calculated for the baseline week and final treatment week. A valid week requires at least 5 usable nights in the 7-day window. The outcome is final-treatment-week average minus baseline-week average; higher values indicate improved sleep efficiency.

Secondary outcomes

• Change in BlazePod RIW Challenge reaction time in milliseconds from baseline to final visit [Baseline to final visit, approximately 5 weeks]: Reaction performance will be measured using the prespecified BlazePod RIW Challenge protocol. The outcome is change in reaction time in milliseconds from baseline to final visit. Lower reaction time indicates better performance.
• Change in BlazePod Speed Tap reaction time in milliseconds from baseline to final visit [Baseline to final visit, approximately 5 weeks]: Reaction performance will be measured using the prespecified BlazePod Speed Tap protocol. The outcome is change in reaction time in milliseconds from baseline to final visit. Lower reaction time indicates better performance.
• Change in WHOOP-derived sleep consistency score from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: WHOOP 4.0-derived sleep consistency score, or an equivalent prespecified WHOOP 4.0-derived sleep timing regularity metric, will be summarized for the baseline week and final treatment week. The outcome is final-treatment-week average minus baseline-week average.
• Change in WHOOP-derived total sleep time in minutes from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: Average nightly total sleep time captured by WHOOP, expressed in minutes, will be calculated for the baseline week and final treatment week. The outcome is final-treatment-week average minus baseline-week average.
• Change in WHOOP-derived resting heart rate in beats per minute from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: Nightly resting heart rate captured by WHOOP, expressed in beats per minute, will be summarized as weekly averages for the baseline week and final treatment week. The outcome is final-treatment-week average minus baseline-week average.
• Change in WHOOP-derived heart rate variability in milliseconds from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: Nightly heart rate variability captured by WHOOP, expressed in milliseconds, will be summarized as weekly averages for the baseline week and final treatment week. The outcome is final-treatment-week average minus baseline-week average.
• Change in WHOOP Recovery Score from baseline week to final treatment week [Baseline week to final treatment week, approximately 5 weeks total including baseline monitoring]: WHOOP Recovery Score, reported on a 0 to 100 scale where higher scores indicate better recovery, will be summarized as weekly averages for the baseline week and final treatment week. The outcome is final-treatment-week average minus baseline-week average.
• Change in VALD dynamometer bilateral average handgrip strength from baseline to final visit [Baseline to final visit, approximately 5 weeks]: Bilateral average handgrip strength will be measured with the prespecified VALD handgrip dynamometer protocol. The outcome is final-visit bilateral average handgrip strength minus baseline bilateral average handgrip strength.
• Change in VALD force plate countermovement jump height from baseline to final visit [Baseline to final visit, approximately 5 weeks]: Countermovement jump height will be measured with the prespecified VALD force plate protocol. The outcome is final-visit jump height minus baseline jump height.
• Number of participants with adverse events and supplement tolerability concerns [From first dose through final visit, approximately 4 weeks]: The number of participants with adverse events, tolerability concerns, dose interruptions, and study-product discontinuations will be summarized by study arm. Events of interest include gastrointestinal symptoms, sedation, dizziness, headache, allergic reaction, skin irritation from wearable use, and study-product discontinuation.

Sex: All, ages: 18 Years to 35 Years, accepts healthy volunteers

Inclusion Criteria:

* Age 18-35 years.
* Current NCAA Division I athlete at UCLA.
* Actively participating in team training and/or competition.
* Willing to wear a WHOOP 4.0 device continuously during the baseline and treatment periods of the study block.
* Able to swallow oral capsules and follow supplement instructions.
* Able and willing to complete daily REDCap surveys and weekly check-ins during the study block.
* Fluent in English.
* Able to provide informed consent.

Exclusion Criteria:

* Known kidney disease or impaired renal function, assessed by participant-completed screening questions and review by the PI or designated study clinician. Screening asks about known kidney disease, reduced kidney function, dialysis, a history of abnormally high magnesium, and prior medical advice to avoid magnesium supplementation. A positive or uncertain response requires clinician review. If safety cannot be established from the questionnaire and participant interview alone, the athlete will not be enrolled. The study will not access medical records or perform research laboratory testing for this screening.
* Current use of non-study magnesium supplements within the past 30 days or unwillingness to avoid non-study magnesium supplements during the study unless approved by the study clinician.
* Diagnosed or treated sleep disorder likely to confound sleep outcomes, such as untreated or unstable insomnia, sleep apnea, or regular use of sleep medication expected to affect study outcomes.
* Known difficulty swallowing capsules or history of choking.
* Known allergy or sensitivity to magnesium or inactive capsule ingredients.
* Known current pregnancy or breastfeeding, determined by participant self-report; no pregnancy testing is planned for this minimal-risk study. A participant who becomes pregnant or begins breastfeeding during the study will stop study product and notify the study team. Additional exclusionary circumstances include use of magnesium-containing laxatives or antacids during the study unless approved by the study clinician, or significant recent or planned changes in training load, diet, sleep medication, or recovery supplements that the investigator believes would confound interpretation.

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• Jeremy Swisher, MD, Principal investigator, University of California, Los Angeles
• Joshua Goldman, MD, Study director, University of California, Los Angeles