10 months 4000IU vitamin D supplementation decreases the risk of vitamin D deficiency but has no effect to physical performance during active military training in high-latitudes – a randomized controlled trial. Authors: Leho Rips (M.D.)1,2,4 corresponding author Alar Toom (M.D., Ph.D.)3 Rein Kuik (M.D.)1 Ahti Varblane (M.D.)4 Hanno Mölder (M.D.)5 Ragnar Kibur (M.D.)5 Marika Laidvere (BSN,MSN)5 Mart Kull (M.D., Ph.D.)7 Jüri-Toomas Kartus (M.D., Ph.D.)1,2,8 Helena Gapeyeva (M.D., Ph.D.) Madis Rahu (M.D.)9 1Sports Medicine and Rehabilitation Clinic, Tartu University Hospital, Puusepa 1ª, 50406 Tartu, Estonia, kliinikum@kliinikum.ee 2Department of Sports Medicine and Rehabilitation, Institute of Clinical Medicine, Faculty of Medicine, University of Tartu Ülikooli 8, 50090 Tartu, Estonia, kmi@ut.ee 3Central Finland Central Hospital, Department of Orthopaedics, Keskussairaalantie 19, 40620 Jyväskylä, Finland kirjaamo@ksshp.fi 4Estonian National Defence College, Centre of Military Disaster Medicine, Riia 12, 51010 Tartu, Estonia kvyoa.meditsiin@mil.ee 5Estonian Defence Forces, Medical Centre of the 2nd Infantry Brigade CSS Battalion, 3a Kose Road, 65603 Võru, Estonia kup@mil.ee 6East-Tallinn Central Hospital, Research Department, Ravi 18, 10138 Tallinn, Estonia info@itk.ee 7Viljandi Hospital, Pärna tee 3, 71024 Jämejala Viljandi County, Estonia vmh@vmh.ee 8University of Gothenburg, Box 100, 405 30, Göteborg, Sweden 9East-Tallinn Central Hospital, Clinic of Medical Rehabilitation, Pärnu mnt 104, 11302 Tallinn, Estonia info@itk.ee 1.General Introduction This dataset contains data collected in Kuperjanov Batalion in Võru in Estonia during the study period in 2021-2022. It is being made public both to act as supplementary data for publications and in order for other researchers to use this data in their own work. The study was approved by the Research Ethics Committee of the University of Tartu no 323/T-3, 337M-25 and 341M-12 and funded by grant no. KVA-0.7-1.1/20/29041 of Estonian Defence Forces. 2.Purpose of the test campaign Vitamin D deficiency with related consequences to human health has growing interest to military specific researchers worldwide. Many specific conditions could put soldiers in to the higher risk of vitamin D deficiency. Under high level of physical pressure during military training might increase the need of vitamin D in human body and therefore supplementation with vitamin D could be crucial for general health and physical fitness. 3.Description of the data in this data set Data was collected in Kuperjanov Batalion in Võru in Estonia during the study period in 2021-2022. Data was collected and saved in PC used for scientific work. All the measurements where done with same instruments. 4.Methods Study design and data collection A longitudinal, triple-blinded (participants, supervisors, researchers), randomized, controlled trial (ClinicalTrials.gov NCT04939636) with a ten-month follow-up period from July 2021 until May 2022 was performed. Anthropometric data collection Body mass (kg) and height (cm) of the conscripts were measured four times by the same nurse at the Kuperjanov Battalion medical center using standardized equipment, and their body mass index (BMI) was calculated in kg/m2. Randomization Computed randomization was used to divide conscripts into two groups: either the Group A , in which conscripts received vitamin D3 capsules (4000 IU/150 µg) and the Group B, in which conscripts received vitamin D3 capsules (600 IU/15 µg). Both types of capsules were standardized for size and colour, administered once per day, in the morning before breakfast, for ten months. Every conscript was provided a personal copy of the information with explanations on the supplementation. The general and daily supplementation protocols were supervised by a member of the local medical staff who had undergone special training. Vitamin D supplementation Standardized coded packages (three per conscript) and capsules (100 per package) were manufactured on special order by HC CLOVER PS, SL (Spain). No commercial sponsoring was involved. The key to the package code numbers was stored in a computer database until the unblinding of the participants. At the end of the study all the packages and capsules were collected and destroyed. Maximum recommended daily supplementation dosage stated by the Estonian State Agency of Medicines is 4000IU. Army Physical Fitness Test (APFT) The APFT is designed to test the endurance and muscular strength and cadriovacscular respiratory fitness of soldiers during the preparation and training session. Results are scored 3 events, 2 minutes push-ups, 2 minutes sit-ups and a 3.2 km (2 miles) run. Results ranging from 0 to 100 points. A minimum 60 points needed in each event to pass the test but minimum 180 points need to be collected. Total positive score ranges 180-300 points. Scoring is based on gender and age and score tables can be found in Army FM 7-22 and Department of the Army Form 705, APFT Score card.(26) Objective measurements of physical performance APFT were conducted three times. Participants’ were informed about the rules for assessing the test results with regard to the APFT guidelines. All APFT physical performance testing took place on the same day, under the same conditions in the same running track, and the results were recorded by the same experienced staff of the Kuperjanov Infantry Battalion. The results and APFT scores of sit-ups, push-ups and 3.2 km running time were collected. The Hand grip test The hand grip test was performed using a validated hydraulic hand dynamometer (Lafayette Instrument Co., USA). Measurements were taken from each participant in the standing position, arms at the side, not touching the body, with the elbow slightly bent. The participant squeezed the dynamometer with as much force as possible. The best result of three trials, with pause of about 10–20 seconds between the trials, was recorded in kilograms. The same procedure was performed for both hands. Blood serum tests Blood serum values of vitamin D (25(OH)D), parathyroid hormone (PTH, normal 1.48–7.83 pmol/l), calcium (Ca, normal 2.15–2.6 mmol/l), ionized calcium (Ca-i, normal 1.12–1.32 mmol/l), were measured four times during the study period: first in July 2021 to provide baseline values, then subsequently in October 2021, January 2022 and May 2022. All blood samples were overnight fasting tests, collected on the same day of the week, and all within the same hour, under standardized conditions. Laboratory measurements Serum samples for clinical chemistry analysis were collected in serum clot activator tubes (BD Vacutainer SST II Advance Plus Blood Collection Tubes, Becton Dickinson and Company, New Jersey, United States). Calcium measurements were performed using the spectrophotometry method (ADVIA® 1800 Clinical Chemistry System, Siemens Healthcare GmbH, Erlangen, Germany). Ionized calcium measurements were performed using ion selective electrodes (AVL 9180 Electrolyte Analyzer, Roche Diagnostics, Germany). The direct chemiluminescent immunoassay method was used for measurement of PTH (ADVIA Centaur XP, Siemens Healthcare GmbH, Erlangen, Germany). Measurements of 25(OH)D were performed using the direct chemiluminescent immunoassay method (LIAISON XL, DiaSorin S.p.A, Saluggia VC, Italy). The direct chemiluminescent immunoassay method was used for measurement of testosterone (ADVIA Centaur TSTII assay, Siemens Healthcare GmbH, Erlangen, Germany). The solid-phase competitive chemiluminescent enzyme immunoassay method was used for measurement of cortisol (IMMULITE 2000 Cortisol, Siemens Healthcare Diagnostics Products Ltd. United Kingdom). All analyses were performed by Synlab Estonia. Following methods were used: patients completed the Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee score and Tampa Scale of Kinesiophobia (TSK-17). Quadriceps and hamstring muscle isokinetic strength was assessed at 60°/sec and 180°/sec using the HumacNorm dynamometer. Functional performance was tested with the single-leg hop test for distance and the Y-balance test for anterior reach EXEL table data sheet description: Nr and code of the participant - participant number, ID Gender M- male, F- female. Age - in years Height - cm Weight - kg Dex - dexter Sin - sinister PTH - parathyroid hormon, pmol/L D-vit - serum vitamin D 25(OH)D, nomol/L i-Ca - serum ionized calcium, mmol/l Ca - serum calcium, mmol/L 4.Sharing Embargo until published.