Vitamin D may play a role in performance and injury risk, yet the required supplementation dosage for collegiate athletes is unclear. The objective of this study was to define the dosage of vitamin D3 supplementation required to beneficially affect serum 25-hydroxyvitamin D (25(OH)D) among a sample of collegiate basketball athletes. This was a quasi-experimental trial, participants were allocated to one of three groups of vitamin D3 daily at the beginning of pre-season training and dependent upon their baseline vitamin D status as follows: insufficient (<75 nmol/L) to 10,000 IU, sufficient (75–125 nmol/L) to 5000 IU and optimal (>125 nmol/L) to no supplementation. Follow-up assessments were completed ~ 5 months later in post season. The majority (n = 13) were allocated to 10,000 IU vs. n = 5 to 5000 IU and n = 2 to no supplementation. The 10,000 IU group showed the greatest change (35.0 ± 27.0 nmol/L) vs. the 5000 IU group (−9.3 ± 9.6 nmol/L) and no supplementation group (−41.6 ± 11.7 nmol/L, p < 0.01). Only 1 participant reached optimal status in the 10,000 IU group. In conclusion, a daily dosage of 10,000 IU vitamin D3 supplementation mitigated the high prevalence of vitamin D deficiency among collegiate basketball players but was insufficient for all to reach sufficient levels.

Conkright, WR, Beckner, ME, Sinnott, AM, Eagle, SR, Martin, BJ, Lagoy, AD, Proessl, F, Lovalekar, M, Doyle, TLA, Agostinelli, P, Sekel, NM, Flanagan, SD, Germain, A, Connaboy, C, and Nindl, BC. Neuromuscular performance and hormonal responses to military operational stress in men and women. J Strength Cond Res 35(5): 1296–1305, 2021—Women have recently been integrated into ground close combat positions; however, there are limited data in women in these roles. We aimed to test the hypothesis that there would be no sex-specific neuromuscular responses, but hormonal signaling would be differentially impacted when exposed to simulated military operational stress (SMOS). Neuromuscular performance was assessed daily using a tactical mobility test (TMT) in 54 male and 15 female military members. Blood was drawn before/after TMT. Mood states were assessed each morning. Unloaded 300-m shuttle time increased 6% in both sexes and remained 7% higher after 1 day of recovery compared with baseline (p < 0.05 for both), whereas performance was maintained in other TMT events (p > 0.05). Growth hormone increased in men, but not women, before to after TMT (p < 0.001 vs. p = 0.086). Women experienced a greater decline in insulin-like growth factor-I across days compared with men ( = 0.778 vs. 0.209, respectively, p < 0.001). Brain-derived neurotrophic factor increased significantly in men only from before to after TMT on day 1 (men: +107% vs. women: +10%) but no difference on days 3 or 4. Cortisol increased 69% from before to after TMT when averaged by sex and day. Negative mood states (depression, tension, and anger) and altered hormonal concentrations were associated with poorer TMT performance. Acute SMOS differentially impacted circulating hormonal milieu in men and women, but no differences in physical performance responses. Unloaded 300-m shuttle was negatively impacted while other fitness domains were maintained. Relationships between performance and mood/endocrine signaling highlight the potential for self-report measures and biomarkers to serve as indicators of performance change.

In the British Army, ground close combat roles have opened to women, however, they must pass the newly developed, gender-neutral Role Fitness Tests for Soldiers (RFT(S)). Due to physiological differences between sexes, training that optimally prepares both sexes for military occupational demands and the RFT(S) is needed. The purpose of this study was to determine the efficacy of a 12-week periodized strength and power programme with concurrent interval training on RFT(S) performance and determine if performance adaptations differed between sexes. 39 recruit-aged (18-35 yrs) participants, including 21 men (29 ± 1 yrs) and 18 women (27 ± 1 yrs), completed the study. Participants performed 3 training sessions per week that included strength and power resistance training followed by interval training. Pre-to post-training, improvements were observed for seated medicine ball throw (4.5%, p < 0.001), casualty drag (29.8%, p < 0.001), single lift (8.9%, p < 0.001), water can carry (13.8%, p = 0.012), repeated lift and carry (6.5%, p < 0.001), 2-km load carriage (7.2%, p < 0.001) and 2-km run (3.2%, p = 0.021). Pre-to post-training improvements were also observed for maximal squat (27.0%, p < 0.001), bench press (8.9%, p < 0.001) and deadlift (24.6%, p < 0.001) maximal strength, but not upper body power or aerobic capacity. No differences in RFT(S) improvements were observed between sexes, however men performed better than women in all RFT(S) and physical performance measures. Concurrent resistance and interval training improves military occupational performance in men and women; however, women may need more training than men to pass the gender-neutral RFT(S). KEYWORDSExercise; fitness; gender; resistance; training Highlights . Twelve weeks of concurrent resistance and interval training improved seated medicine ball throw, casualty drag, single lift, water can carry, repeated lift and carry, 2-km load carriage and 2-km run performance, military occupational performance measures that comprise the British Army Role Fitness Test for Soldiers (RFT(S)). . Men and women demonstrated similar military occupational performance improvements from pre-to post-training, however, men performed better than women in all measures. . Simple linear regression analyses between improvements in RFT(S) tasks and measures of physical fitness (one-repetition maximal strength, upper body power, lower body power, aerobic capacity) demonstrated limited significant associations suggesting that military occupational performance improvement relies on simultaneous development of multiple fitness domains.

METHODS: Sixty U.S. Army infantry recruits (97% male) provided fasted blood and saliva samples at the beginning (PRE; week 0) and end (POST; week 22) of IMT. Peripheral leukocyte distribution was measured by flow cytometry, and T-cell and innate cell reactivity were measured by mitogen (anti-CD3/CD28 or lipopolysaccharide (LPS))-stimulated cytokine profiles in 48hr whole blood culture. Latent reactivation of Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and herpes simplex virus 1 (HSV1) was measured in saliva by qPCR. RESULTS: Lymphocyte percentage increased (+28%) while granulocytes (-15%) and monocytes (-13%) decreased PRE to POST (all P < 0.01). This lymphocytosis was driven by an increase in natural killer cells (+19%), and accompanied by decreases in B-cells (-9%) and T-cells (-5%; all P < 0.01). Within T-cell subsets, terminally differentiated CD4+ (+22%) and CD8+ (+30%) cells increased while those of effector memory CD4+ cells (-11%), effector memory CD8+ cells (-54%) and central memory CD8+ cells (-15%) decreased (all P ≤ 0.02). T-cell production of most measured cytokines following anti-CD3/CD28 stimulation increased from PRE to POST (P < 0.05). Conversely, stimulation with LPS resulted in reduced production of most measured cytokines (P < 0.05). Prevalence of EBV reactivation was higher POST (n=30) relative to PRE (n=19; P = 0.01), but neither VZV nor HSV1 reactivation was observed at either time point. CONCLUSION: Lymphocytosis, maturation of CD4+/CD8+ T-cell subsets, and heightened T-cell reactivity at POST collectively suggests an appropriate immune response to pathogen challenges during IMT. Though EBV reactivation was increased at POST, no evidence of VZV or HSV1 reactivation, which are more common during severe stress, was observed. Findings suggest that EBV reactivation during IMT was likely appropriately controlled in recruits and that immune-competence was relatively uncompromised at the end of IMT.

Bone stress injuries (BSI) are a common musculoskeletal condition among exercising and military populations and present a major burden to military readiness. The purpose of this investigation was to determine whether baseline measures of bone density, geometry, and strength, as assessed via peripheral quantitative computed tomography (pQCT), are predictive of tibial BSI during Marine Officer Candidates School training. Tibial pQCT scans were conducted prior to the start of physical training (n = 504; Male n = 382; Female n = 122) to measure volumetric bone mineral density (vBMD), geometry, robustness, and estimates of bone strength. Bone parameters were assessed at three tibial sites including the distal metaphysis (4% of tibial length measured from the distal endplate), mid-diaphysis (38% of tibial length measured from the distal endplate), and proximal diaphysis (66% of tibial length measured from the distal endplate). Injury surveillance data was collected throughout training. Four percent (n = 21) of the sample were diagnosed with a BSI at any anatomical site during training, 10 injuries were of the tibia. Baseline bone parameters were then tested for associations with the development of a tibial BSI during training and it was determined that cortical bone measures at diaphyseal (38 and 66%) sites were significant predictors of a prospective tibial BSI. At the mid-diaphysis (38% site), in a simple model and after adjusting for sex, age, and body size, total area [Odds Ratio (OR): 0.987, 0.983], endosteal circumference (OR: 0.853, 0.857), periosteal circumference (OR: 0.863, 0.824), and estimated bending strength (SSI; OR: 0.998, 0.997) were significant predictors of a BSI during training, respectively, such that lower values were associated with an increased likelihood of injury. Similarly, at the proximal diaphysis (66% site), total area (OR: 0.989, 0.985), endosteal circumference (OR: 0.855, 0.854), periosteal circumference (OR: 0.867, 0.823), robustness (OR: 0.007, 0.003), and SSI (OR: 0.998, 0.998) were also significant predictors of BSI in the simple and adjusted models, respectively, such that lower values were associated with an increased likelihood of injury. Results from this investigation support that narrower bones, with reduced circumference, lower total area, and lower estimated strength are associated with increased risk for tibial BSI during military training.

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The vertical jump (VJ) test is often administered in various sport sectors such as the NBA and NFL combines in order to possibly predict future athlete success. The VJ test is designed to assess lower body peak power by having subjects explosively jump vertically and recording the maximum jump height. Previous research studies have examined different focal points and/or appropriate recovery protocols that may contribute to higher jumping performance in various types of athletes. However, many athletes perform in a competitive setting in their respective sports. Thus, replicating a "competitive environment" during a VJ assessment test setting may elicit an ergogenic effect on an individual's jumping performance. PURPOSE: to determine if competition will have an impact on vertical jump performance in males with an athletic background. METHODS: Twenty-eight no less than averagely fit college aged males had descriptive data collected (i.e. age, HT, WT, BF%) and their reach height measured. Participants then completed a dynamic 8 min warmup and then received a 4 min passive recovery (PR) period. Subjects then completed four familiarization jumps in a counter movement manner and then had another 4 min of PR. After the 2nd 4 min PR period, participants completed six jumps for both jump series with thirty seconds of rest between jumps and 6 min of PR between each jump series. The jump series protocol consisted of two separate counterbalanced jump series. One series consisted of a solo jump (SJ) setting where the subject jumped alone. The competitive jump series occurred where one subject jumped against another subject. A paired-samples t-Test was used to analyze the highest SJ and CJ jumps with significance determined at an alpha level of 0.05. RESULTS: CJ (73.97 + 10.20 cm) was significantly different (p = 0.002) than SJ (72.75 + 9.86 cm). CONCLUSION:The results of the present study suggest that the VJ test competitive format may have elicited an increase in the VJ performance. Future research is needed to assess the effect of competition on VJ performance in female athletes as well as male athletes who specialize in sports with repetitive jumping movements.