Exploring the effects of L-carnitine supplementation on CrossFit® performance

ISRCTN	ISRCTN14089170
DOI	https://doi.org/10.1186/ISRCTN14089170
ClinicalTrials.gov (NCT)	Nil known
Clinical Trials Information System (CTIS)	Nil known
Protocol serial number	CARCT1
Sponsor	Universidad Nacional Autónoma de México
Funder	Universidad Nacional Autónoma de México

Submission date: 07/10/2024
Registration date: 29/01/2025
Last edited: 28/02/2025

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Other

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
This study aims to investigate whether L-carnitine supplementation can improve performance in recreational CrossFit® athletes during a high-intensity workout called "Cindy." Specifically, whether taking L-carnitine will increase the number of repetitions completed during the workout and its effects on perceived exertion, blood pressure, and any potential side effects like gastrointestinal discomfort.

Who can participate?
The study includes adult male volunteers between the ages of 18 and 35 years old who had at least six months of CrossFit® experience and had previously completed the "Cindy" workout

What did the study involve?
Participants will be randomly assigned to take either a 3 g dose of L-carnitine or a placebo 90 minutes before performing the "Cindy" workout. Each participant takes part in two separate sessions: one with L-carnitine and one with a placebo. During the workout, the total number of repetitions, ratings of perceived exertion (RPE), blood pressure and any side effects, such as gastrointestinal issues, are recorded.

What were the possible benefits and risks of participating?
While participants will not experience direct benefits from the study, the findings provide valuable information about the effects of L-carnitine on high-intensity exercise performance. There are minimal risks involved, such as reporting minor gastrointestinal discomfort and difficulty sleeping after taking L-carnitine, but no serious adverse effects are expected to be observed.

Where was the study run from?
The study was conducted at a CrossFit® club within the Faculty of Higher Studies of Zaragoza.

When did the study start and how long did it run for?
January 2023 to December 2023

Who funded the study?
Universidad Nacional Autónoma de México

Who was the main contact?
Dr Azucena Ojeda Sanchez, a.ojeda@zaragoza.unam.mx, azucenaojedasan@yahoo.com.mx

Contact information

Prof Beat Knechtle
Scientific

Gallen Am Vadianplatz, Vadianstrasse 26
St. Gallen
9001
Switzerland

ORCID ID	0000-0002-2412-9103
Phone	+41 71 534 01 31
Email	beat.knechtle@hispeed.ch

Dr Asli Devrim Lanpir
Public

Collins Ave Ext, Artane - Whitehall
Dublin 9
D09 W6Y4
Ireland

ORCID ID	0000-0002-4267-9950
Phone	+353 (1) 700 5000
Email	aslidevrimlanpir@gmail.com

Dr Azucerna Ojeda Sanchez
Principal investigator

Epidemiología y Salud Pública, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México
Mexica City
04510
Mexico

Phone	+52 36011000 Ext 69326
Email	a.ojeda@zaragoza.unam.mx

Study information

Primary study design	Interventional
Study design	Randomized double-blind placebo-controlled crossover study
Secondary study design	Randomised controlled trial
Participant information sheet	46188_PIS.pdf
Scientific title	The effects of acute L-carnitine supplementation on CrossFit® performance: a randomized, double-blind, placebo-controlled crossover study
Study objectives	Primary Hypothesis: Acute L-carnitine supplementation will enhance exercise performance, as measured by the total number of repetitions completed by recreational CrossFit® athletes, compared to a placebo. Secondary Hypothesis: L-carnitine supplementation will result in lower ratings of perceived exertion (RPE) and more favorable blood pressure (BP) measurements during exercise compared to a placebo.
Ethics approval(s)	Approved 27/11/2023, The Research Ethics Committee of National Autonomous University of Mexico (Av. Universidad 3004, Copilco Universidad, Coyoacán, Mexico City, 04510, Mexico; +52 55 5622 0000; etica.enlace@zaragoza.unam.mx), ref: FESZ/CEI/31/23
Health condition(s) or problem(s) studied	The acute effects of L-carnitine supplementation on exercise performance in recreational CrossFit® practitioners
Intervention	In this randomized, double-blind, placebo-controlled crossover study, a free online randomisation tool (randomiser.org) was used to assign CrossFit practitioners to groups. They participated in two workout sessions in a crossover design, with no additional follow-up activities afterwards. Participants were assigned to receive either a 3 mg dose of L-carnitine tartrate or a placebo. The L-carnitine tartrate dose was administered 90 minutes before the “Cindy” workout, a CrossFit® exercise regimen. Participants completed both the L-carnitine and placebo conditions in separate sessions, with the order of administration randomized to minimize bias. The total number of repetitions completed during the workout was recorded to assess exercise performance. In addition, ratings of perceived exertion (RPE) and blood pressure (BP) measurements were collected during each session. The percent change in performance between sessions was calculated to evaluate any potential learning effect on the ergogenic benefits of L-carnitine supplementation.
Intervention type	Supplement
Primary outcome measure(s)	Exercise performance was measured using the total number of repetitions completed during the "Cindy" workout, a high-intensity CrossFit® protocol immediately after the workout in each session
Key secondary outcome measure(s)	1. Ratings of Perceived Exertion (RPE) were measured using a standard Borg scale at the end of the workout 2. Blood Pressure (BP) was measured using a standard sphygmomanometer before and after the workout session 3. Gastrointestinal issues were measured using participant self-reporting at the end of the workout
Completion date	31/12/2023

Eligibility

Participant type(s)	Healthy volunteer
Age group	Adult
Lower age limit	18 Years
Upper age limit	35 Years
Sex	Male
Target sample size at registration	20
Total final enrolment	20
Key inclusion criteria	1. Trained adult males aged 18-35 years old 2. A minimum of six months of CrossFit® experience 3. Required to have previously completed the “Cindy” workout routine
Key exclusion criteria	1. Diagnosed illnesses 2. Smoking 3. Recent use of medications or supplements (within the last three months) 4. Family history of seizures 5. Musculoskeletal injuries
Date of first enrolment	27/11/2023
Date of final enrolment	27/12/2023

Locations

Countries of recruitment

Mexico

Study participating centre

Faculty of Higher Studies of Zaragoza

Avenida Guelato 66
Col. Ejército de Oriente
Mexico City
09230
Mexico

Results and Publications

Individual participant data (IPD) Intention to share	Yes
IPD sharing plan summary	Available on request
IPD sharing plan	The datasets generated during and/or analyzed during the current study will be available upon request from Beat Knechtle, beat.knechtle@hispeed.ch. The data includes individual participant data (IPD) related to performance outcomes, ratings of perceived exertion (RPE), blood pressure measurements, and any reported side effects. The data will be anonymized to protect participant confidentiality and will be shared with researchers upon request for the purpose of replicating or extending the findings of the study. Access will be granted to individuals or institutions involved in academic or scientific research, subject to approval by the study’s ethics committee. Consent for data sharing was obtained from participants as part of the informed consent process.

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Participant information sheet			21/10/2024	No	Yes
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes

Additional files

46188_PIS.pdf: Participant information sheet

Editorial Notes

28/02/2025: Contact details updated.
08/10/2024: Study's existence confirmed by The Research Ethics Committee of National Autonomous University of Mexico.