High dose vitamin D supplementation decreases the risk of deficiency in male conscripts, but has no effect on physical performance-A randomized study.

Purpose: Physical load during military training might increase the need for vitamin D; therefore, supplementation could be beneficial for 25(OH)D serum levels and physical performance. Methods: One hundred and twelve male conscripts were randomized into two vitamin D oil capsule supplementation groups: 55 participants in the 600 IU group and 57 in the 4000 IU group with a follow-up period from July 2021 to May 2022. Physical fitness tests were performed in July, October and May. Hand grip strength tests were performed in July, October and January. Blood serum (25(OH)D), parathyroid hormone PTH), calcium and ionized calcium (i-Ca) values were measured in July, October, January and May. Results: The 600 IU group had a lower (p < 0.001) value of 25(OH)D at all time points compared to the 4000 IU group, except at baseline. None of the subjects in the 600 IU group reached sufficient levels of 75 nmol/L of 25(OH)D in January and May. In May, 60% of participants in the 600 IU group and 30% in the 4000 IU group had 25(OH)D levels under 50 nmol/L. No significant differences in PTH or i-Ca values were found between the study groups at any time point. No significant differences at any time point were found in the physical fitness test or hand grip strength test between the groups. Conclusion: A 10-month vitamin D supplementation with 4000 IU decreased the incidence of vitamin D deficiency (<75 nmol/L) in young, male army conscripts during wintertime, but no differences in physical performance were found compared to 600 IU supplementation. Level of Evidence: Level I, Prospective randomized study.

Severe deficiency of vitamin D has no negative effect on physical performance during military training.

BACKGROUND: Decreased physical fitness and inferior physical performance are potentially life-threatening risk factors in a combat situation. To examine the effect of vitamin D on physical performance, a prospective study of young men conscripts in the Estonian Army was designed. The hypothesis of the study was that severe deficiency of vitamin D has a negative effect on physical performance. METHODS: All conscripts (N.=410) entering 10-month military service in July 2015 at the Kuperjanov Battalion were asked to participate. Initially, a total of 98 conscripts volunteered to participate. A prospective longitudinal study with a 10-month follow-up period was performed. The Army Physical Fitness Test (APFT) was performed three times, and hand grip strength, and blood serum values of 25(OH)D, parathyroid hormone (PTH) and calcium (Ca) were measured four times. RESULTS: A significant decrease in the levels of 25(OH)D compared with baseline values were found, with a lowest mean value of 31.9 nmol/L in March 2016 (P<0.001). No significant differences were found in serum Ca levels. In March 2016, PTH was significantly higher in the severe deficiency group (<25 nmol/L of 25(OH)D) (P=0.02). No significant differences were found in terms of the APFT or hand grip strength between conscripts with severe deficiency of 25(OH)D or values >25 nmol/L. The main finding of the present study was that severe 25(OH)D deficiency was common among male conscripts during the winter season but had no negative effect on physical performance in terms of the APFT test and hand grip strength test. CONCLUSIONS: Severe vitamin D deficiency during the winter season is common but has no negative effect on physical performance in young, physically active men in military service.

Seven-month wintertime supplementation of 1200 IU vitamin D has no effect on hand grip strength in young, physically active males: A randomized, controlled study.

Background: There has been a growing interest in the role of vitamin D for the well-being and physical performance of humans under heavy training such as conscripts in military service; however, there is a lack of long-term supplementation studies performed on members of this type of young, physically active, male population. The hypothesis of the study was that vitamin D supplementation during wintertime will decrease the prevalence of critically low vitamin D blood serum levels and increase hand grip strength during the winter season among young male conscripts. Study Design: Longitudinal, triple-blinded, randomized, placebo-controlled trial. Methods: Fifty-three male conscripts from the Estonian Army were randomized into two groups: 27 to an intervention group and 26 to a placebo group. The groups were comparable in terms of their demographics. The intervention group received 1200 IU (30 µg) capsules of vitamin D3, and the control group received placebo oil capsules once per day. The length of the follow-up was 7 months, from October 2016 until April 2017. Blood serum vitamin D (25(OH)D), parathyroid hormone (PTH), calcium (Ca), ionized calcium (Ca-i), testosterone and cortisol values, and hand grip strength were measured four times during the study period. Results: The mean 25(OH)D level decreased significantly in the control group to a critically low level during the study, with the lowest mean value of 22 nmol/l found in March 2017. At that time point, 65% in the control group vs 15% in the intervention group had 25(OH)D values of less than 25 nmol/l (p < 0.001). In the intervention group, the levels of 25(OH)D did not change significantly during the study period. All other blood tests revealed no significant differences at any time point. The corresponding result was found for hand grip strength at all time points. Conclusion: Long-term vitamin D supplementation during wintertime results in fewer conscripts in the Estonian Army with critically low serum vitamin D (25(OH)D) levels during the winter season. However, this did not influence their physical performance in the form of the hand grip strength test.

Self-Reported Knee Pain Does Not Impact Physical Training Negatively in Conscripts.

INTRODUCTION: Despite the great number of investigations on the effects of injuries during military service, there is limited information available on the use of self-reported instruments. This study evaluated self-reported knee pain (KP) and its effect on physical performance during military service in the Estonian Defense Forces. MATERIAL AND METHODS: Ninety-five male conscripts aged 19-25 years were divided into two study groups based on the occurrence of KP or not. Self-reported KP and function according to the Knee Injury and Osteoarthritis Outcome Score (KOOS) were measured. Physical fitness level was scored using the Army Physical Fitness Test (APFT). KOOS and APFT were measured in the beginning and at the end of the 6-month period of military service. RESULTS: Significant differences in favor of the group without KP (P < 0.001) were found for all subgroups of the KOOS. In spite of KP, the physical condition improved significantly (P < 0.001) in both study groups as measured with both the APFT test (22.2% increase) and running time (10.3% decrease). CONCLUSION: In conclusion, self-reported KP and limited function according to KOOS did not hinder the improvement of physical condition and running speed as assessed by APFT in Estonian conscripts.