Correction: Maximal and sub-maximal exercise tests alter PBMC microRNA expression: insights into sport- and sex-specific variations
Year: 2025
Type: erratum
Abstract: 1 Introduction MicroRNAs (miRNAs) are small non-coding RNAs (18–24 nucleotides) that regulate gene expression by binding to messenger RNAs (mRNAs), promoting their degradation or inhibiting translation. This regulation is essential for cellular homeostasis, immune function, and tissue repair (Rocchi et al., 2021). Measuring microRNA expression before and after exercise offers valuable insights into athletes' physiological adaptations (Da Silva et al., 2020). Exercise-induced changes in microRNA levels may reflect the body's adaptive responses, and these alterations have been observed in various biological samples including serum, plasma, saliva, and muscle biopsies (Da Silva et al., 2020). However, studies specifically examining microRNAs in peripheral blood mononuclear cells (PBMCs) remain scarce (Radom-Aizik et al., 2012; Carbonare et al., 2022). PBMCs—comprising lymphocytes, monocytes, and dendritic cells—are critical immune cells that transiently increase in circulation following acute exercise. Endurance training may enhance the expression of specific PBMC microRNAs associated with immune function, recovery, and adaptation (Radom-Aizik et al., 2012; Carbonare et al., 2022). Yet, comparative studies of microRNA expression between different endurance sports or between sexes are still lacking. Runners and cyclists display distinct biomechanical and physiological characteristics. Runners often exhibit higher VO2max on a treadmill, whereas cyclists may reach similar VO2max levels on a cycle ergometer (Millet et al., 2009). Sport-specific adaptations, such as differences in ventilatory thresholds, cardiac output, and muscle recruitment, can influence submaximal parameters even without changes in VO2max. Notably, running imposes impact forces absent in cycling (Millet et al., 2009), which may differentially affect physiological responses and microRNA expression. Biological sex also shapes physiological traits through hormonal, chromosomal, and epigenetic interactions (Khramtsova et al., 2019; Oliva et al., 2020). Recently, microRNAs have emerged as important mediators of sex-specific biological differences (Cui et al., 2018), making it essential to explore microRNA expression in male and female athletes under exercise stress. This study aimed to determine the PBMC microRNA expression profile in female and male runners and cyclists before and after (i) a maximal exercise (VO2max) test, and (ii) a submaximal exercise (85% of VO2max) until exhaustion. 2 Methods 2.1 Study design and participants Each subject received information about the study and signed an informed consent form after approval from the Tel Aviv University Ethics Committee (approval No. 0003766-1). All informed consent forms signed by the subjects are in the files of the principal researcher at Tel Aviv University, Israel. We enlisted endurance runners and cyclists from structured, non-professional competitive sports teams in Israel, which are registered with national athletic or cycling associations. These teams operate within organized training frameworks, led by certified coaches, and participate in regular weekly training sessions, as well as local and national competitions throughout the year. Although the athletes are not professional in the contractual or salaried sense, they train and compete at a high level of commitment and performance. To further support their classification as competitive endurance athletes, we used objective inclusion criteria: runners were required to run at least 50 km per week (mean 67 ± 15.6 km), and cyclists to cycle at least 120 km per week (mean 174 ± 54 km). According to self-reports, the athletes trained at an intensity of 80% or more of their maximum heart rate. The runners had a mean age of 43 ± 6.5 years and a body mass index (BMI) of 23.2 ± 2.61. The cyclists had a mean age of 46 ± 7 years and a BMI of 22.9 ± 3.25. The ethnic origin of all the participants in this study was Ashkenazi Jews (originating from Europe and North America). The control group participants were selected from the general population and consisted of healthy, active individuals who engaged in light physical activity. Their weekly walking or running volume was less than 5 km per week, performed for recreational purposes to maintain general health and lifestyle rather than for competition. The control group had a mean age of 41 ± 7.4 years and a BMI of 23.9 ± 4.01. To ensure comparability between athletes and the control group, participants were selected to match as closely as possible in terms of age, BMI, and health status, with the primary difference being the level of physical activity. Inclusion criteria were: (1) age between 30 and 55 years. Efforts were made to recruit participants of similar average age in all study groups, resulting in a comparable age distribution across the study arms; (2) BMI within the normal range (20.0–24.9 kg/m2); (3) omnivorous dietary pattern to reduce dietary variability; and (4) self-reported good health, with no history or current evidence of chronic diseases, including cardiovascular, metabolic, gastrointestinal, or autoimmune disorders. Exclusion criteria included: (1) smoking or use of nicotine products; (2) use of medications or dietary supplements known to influence vascular function, immune response, or gut microbiota (e.g., antibiotics, probiotics, prebiotics, corticosteroids) in the 3 months before the study; (3) adherence to vegetarian, vegan, ketogenic, or other specialized diets; and (4) recent participation in another clinical or dietary intervention study. An online survey was completed by each participant, which provided detailed information about their diet and training exercises. Participants were instructed not to consume any pre-workout supplements, such as caffeine or nitric oxide supplements, drink coffee, and avoid any ergogenic dietary supplements that could affect their vascular function and enhance athletic performance for 72 h before their arrival for the exercise tests. They were also required to fast for 12 h before the tests to ensure all participants arrived at a comparable energy status. 2.2 Exercise tests 2.2.1 Maximal exercise test (VO2max test) Each participant underwent a maximal exercise test to assess their aerobic capacity ("exercise test A"). Maximal oxygen uptake (VO2max) and ventilatory thresholds (VT1 and VT2) were determined using a metabolic cart (Quark CPET, COSMED S.r.l., Rome, Italy) (Evans et al., 2015; Shephard, 1984). The system was calibrated prior to each test session according to the manufacturer's specifications, including gas and flowmeter calibration. Cyclists performed the test on a stationary SRM Ergometer (SRM GmbH, Jülich, Germany), starting at an initial workload of 80 W. The workload increased incrementally by 20 W every minute, while participants were instructed to maintain a pedaling cadence of 80 revolutions per minute (RPM). The test was terminated at volitional exhaustion or when cadence dropped below 60 RPM despite encouragement. Runners and control participants performed a treadmill running test using an h/p/cosmos Saturn 300 treadmill (h/p/cosmos sports and medical gmbh, Nussdorf-Traunstein, Germany). The test began at a speed corresponding to approximately 50% of the participant's estimated running economy, increasing by 1 kph every minute until volitional exhaustion. This protocol was selected to reflect the primary mode of physical activity in these groups. Control participants performed the treadmill test rather than a cycling test, as their habitual activity involved walking or light running and not cycling. To standardize intensity across individuals, all tests were individualized and based on each participant's fitness level, with intensity progression tailored to elicit maximal effort within 8–12 min of exercise. 2.2.2 Submaximal exercise test One week later, participants completed a submaximal constant-load exercise test ("exercise test B") to evaluate time-to-exhaustion at 85% of their previously determined VO2max (Laursen et al., 2007). Runners and control subjects performed the test on the same h/p/cosmos treadmill used for the maximal test, while cyclists used the SRM Ergometer. In the present study, differences in microRNA expression were assessed as within-group percentage changes in response to exercise. Specifically, post-exercise microRNA expression levels were compared to pre-exercise levels within each group: runners were evaluated before and after running, and cyclists were evaluated before and after cycling. Each group was assessed in its respective sport-specific exercise modality. Heart rate (HR) was continuously monitored using a POLAR watch (Polar Electro Oy, Kempele, Finland), and capillary blood lactate concentrations were measured every 5 min during the test using a Lactate Scout + handheld analyzer (EKF Diagnostics GmbH, Barleben, Germany). The test was terminated at volitional exhaustion or upon any signs of physiological distress, in accordance with safety protocols. 2.3 Blood collection, PBMC isolation, and PBMC microRNA analysis 2.3.1 Blood collection Peripheral blood samples were collected from participants following standard venipuncture procedures before and immediately after each exercise test (A and B). Resting values served as baseline levels. Blood was drawn into EDTA-containing tubes (purple cap Vacutainer™ tubes, BD Biosciences, Franklin Lakes, NJ, United States). 2.3.2 Complete blood counts and white blood cells differential The differential count of white blood cells (WBC) was performed using an automated hematology analyzer equipped with VCS technology (Volume, Conductivity, Scatter). Whole blood was analyzed on a DxH 800 Hematology Analyzer (Beckman Coulter, B46899), a device designed to provide complete blood counts and perform leukocyte differential using advanced laser light scatter and electrical impedance methods. This technology allows for precise classification of leukocyte subpopulations, enabling rapid and reliable analysis. The analyzer provides high-throughput capability, ensuring accurate and in clinical Blood for PBMC microRNA analysis Blood samples were using Whole blood was to the tubes and for min at revolutions per minute to and PBMC from blood PBMC and were to a and for min at RPM was and PBMC was in and to tubes Germany). were for 5 min at The was and tubes with PBMC were at 80 underwent PBMC samples were using United by using and at at for 20 min and with at at for was with in and at at for 5 was in The and were measured using a United States). the and initial were performed by specific procedures may not However, based on standard associated with the and the following procedures were from was used for with the following the manufacturer's was performed on an United in a of approximately 20 per and were using and were to the using was with enabling the of known and of counts was performed using the mean of control of and of expression analysis was using the was to control the rate and with and an were differentially analysis and was using the and all analysis was performed by a using were and using the by and using The between the was using under and differential expression analysis were performed using with between microRNA expression and physiological (e.g., training were within the values were using the were using of PBMC count the and was performed in by analysis. 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Source: Frontiers in Physiology
Institutions: Tel Aviv University, Assaf Harofeh Medical Center
Language: English
Subfield: Rehabilitation
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $3,801
OpenAlex ID: W4415984387
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