Description

Participants

All participants were informed about the procedures and provided signed informed consent. The study was conducted in accordance with the guidelines of the Declaration of Helsinki Declaration for Research Involving Human Subjects and the protocol was approved by the Institutional Review/Ethics Committee of the Catholic University of Murcia (Code: CE052416).

Study design

Randomized, double-blind, placebo-controlled, crossover clinical trial with 2 study groups (vitamin B12 and placebo). Cyclists were instructed to take the supplement (vitamin B12 or placebo) with breakfast on the three days before the tests and 3h before the test day, and to continue with their usual diet and training programme. Subjects in both groups were instructed not to consume vitamin B12-rich foods for 7 days before and during the study. Between each intervention (B12 and Placebo) there was a 7-day washout period.

Procedures

Participants visited the laboratory on three occasions. Visit 1 consisted of a medical examination and a blood draw to determine health status. At visits 2 and 3, a 24-hour diet reminder and a Wingate test, mental fatigue test and venous blood draw were performed. The sports nutritionist prescribed a standardized breakfast before each testing session (visits 2 and 3).

Pre- and post-evaluation test

Visit 1:

Health status blood test: A general blood test will be performed both pre- and post-supplementation. The blood will be drawn through a vein (fasting).

Medical examination: A medical history of family and personal history, an electrocardiogram (ECG) at rest and a medical examination (auscultation, blood pressure, etc.) will be carried out to certify that the person is healthy and does not present a risk to participate in the study (Fasting).

Body composition by absorptiometric densitometry (DXA): A body composition test will be performed using the double energy absorptiometric densitometry technique (X-rays), with the aim of determining parameters of fat mass, fat-free mass and fat percentage. In addition, anthropometry will also be used to determine changes in body composition (fat and muscle mass) (Fasting).

Visits 2 and 3:

Anaerobic power and mechanical power output: After a standardised breakfast, a Wingate test was performed on a cycle ergometer. The Wingate test (WAnT) consisted of a 30 s sprint on a cycle ergometer (Monark Ergomedic 894E Peak Bike, Vansbro, Sweden). Breaking strength was held constant at 7.5% of each individual's body mass. All participants were verbally encouraged to pedal as fast as possible throughout the sprint.

Mental fatigue test: All participants will be tested for the evaluation of reaction time to a sequence of lights set by the investigator before and after the performance test.

Biochemical markers: A venous blood draw will be performed by medical personnel before and after the performance test, in which vitamin B12, creatine kinase and lactate dehydrogenase levels will be analyzed.

All data of the subjects who participated in the study were stored in a computer system with a security key. In addition, some of the data was also recorded on paper and kept under lock and key, accessible only to the researchers of this project.