Longitudinal Changes in Fat and Lean Mass: Comparisons between 3D-Infrared and Dual-Energy X-ray Absorptiometry Scans in Athletes.

The low cost and portability of three-dimensional (3D) infrared body scanners make them an attractive tool for body composition measurement in athletes. The main purpose of this study was to compare total body fat percentage (BF%) and total lean mass (LM in kg), in a cohort of collegiate athletes, using a 3D infrared body scanner versus a dual energy x-ray absorptiometry (DXA) scanner. Phase I was a pre-season cross-sectional analysis of 61 (39 male) athletes while Phase II was a longitudinal subset analysis of 38 (27 male) student-athletes who returned to the laboratory for post-season scans (Post minus pre-season change). Both the 3D and DXA scans were performed within 20-minutes of one another in the same room, wearing the same clothing. Paired t-tests were used to compare the mean values (BF% and LM) between measurement devices with estimated effects size calculated using Cohen's d. Data reported as mean±SD. Mean difference (DXA minus 3D) in LM were significantly higher using the 3D scan (5.84 ± 3.55kg; p < 0.001; d = 0.90) compared to the DXA scan, while significantly underestimating BF% (-4.57 ± 4.67%; p < 0.001; d = 1.6) in Phase I analyses. In Phase II analyses, significant differences in the change (post-season minus pre-season change) values were found between methods for LM (4.45 ± 5.04; p < 0.001; d = 0.90), while BF% (-0.41 ± 2.06; p= 0.223; d = 0.2) showed no significant differences. In summary, the 3D and DXA scan values for LM and BF% were not interchangeable in cross-sectional nor longitudinal body composition analyses in collegiate athletes. Close agreement was only observed in longitudinal analyses of BF% and requires further validation with larger cohorts.

Vitamin D supplementation and body composition changes in collegiate basketball players: a 12-week randomized control trial.

Background: Vitamin D promotes bone and muscle growth in non-athletes, suggesting supplementation may be ergogenic in athletes. Our primary aim was to determine if modest Vitamin D supplementation augments favorable body composition changes (increased bone and lean mass and decreased fat mass) and performance in collegiate basketball players following 12 weeks of standardized training. Methods: Members of a men's and women's NCAA D1 Basketball team were recruited. Volunteers were randomized to receive either a weekly 4000 IU Vitamin D3 supplement (D3) or placebo (P) over 12 weeks of standardized pre-season strength training. Pre- and post-measurements included 1) serum 25-hydroxy vitamin D (25(OH)D); 2) body composition variables (total body lean, fat, and bone mass) using dual-energy X-ray absorptiometry (DXA) scans and 3) vertical jump test to assess peak power output. Dietary intake was assessed using Food Frequency questionnaires. Main outcome measures included changes (∆: post-intervention minus pre-intervention) in 25(OH)D, body composition, and performance. Results: Eighteen of the 23 players completed the trial (8 females/10 males). Eight received the placebo (20 ± 1 years; 3 females) while ten received Vitamin D3 (20 ± 2 years; 5 females). Weekly Vitamin D3 supplementation induced non-significant increases (∆) in 25(OH)D (2.6 ± 7.2 vs. -3.5 ± 5.3 ng/mL; p = 0.06), total body bone mineral content (BMC) (73.1 ± 62.5 vs. 84.1 ± 46.5 g; p = 0.68), and total body lean mass (2803.9 ± 1655.4 vs. 4474.5 ± 11,389.8 g; p = 0.03), plus a non-significant change in body fat (-0.5 ± 0.8 vs. -1.1 ± 1.2%; p = 0.19) (Vitamin D3 vs. placebo supplementation groups, respectively). Pre 25(OH)D correlated with both Δ total fat mass (g) (r = 0.65; p = 0.003) and Δ total body fat% (r = 0.56; p = 0.02). No differences were noted in peak power output ∆ between the D3 vs. P group (-127.4 ± 335.4 vs. 50.9 ± 9 W; NS). Participants in the D3 group ingested significantly fewer total calories (-526.2 ± 583.9 vs. -10.0 ± 400 kcals; p = 0.02) than participants in the P group. Conclusions: Modest (~517 IU/day) Vitamin D3 supplementation did not enhance favorable changes in total body composition or performance, over 3 months of training, in collegiate basketball players. Weight training provides a robust training stimulus for bone and lean mass accrual, which likely predominates over isolated supplement use with adequate caloric intakes.

Too Tall for the DXA Scan? Contributions of the Feet and Head to Overall Body Composition.

Accurate assessment of total body composition in tall (>1.96m) individuals using dual energy x-ray absorptiometry (DXA) scans is problematic due to current height restrictions of the scan table. The aim of this investigation was to quantify absolute and relative contributions of fat, bone and lean mass, of the feet and head regions, to whole-body composition DXA scan totals. Whole-body DXA scans were performed in collegiate athletes. Athlete DXA scans were included in data analyses if the entire body fit within the confines of scan table area. The feet region of interest (ROI) was delineated at the ankle joint mortise, marked superiorly by the inferior margin of the tibial plafond and encompassing all inferior anatomical structures. The head region was calculated by the DXA scan software. Both absolute (kg) and relative (feet/whole-body x 100 = feet mass %) contributions to body composition were calculated. Data presented as mean±SD. 132 National Collegiate Athletic Association (NCAA) athletes (85 female) underwent DXA scans which met the inclusion criteria. The feet region represented: 1.9±0.3kg (2.6±0.3%) of total mass; 0.4±0.3kg (2.6±0.5%) of fat mass; 1.3±0.3kg (2.5±0.3%) of lean mass; and 0.14±0.0kg (5.4±0.6%) of bone mineral content (BMC). The head region represented: 4.8±0.5kg (6.9±0.8%) of total mass; 1.2±0.2kg (8.2±3.0%) of fat mass; 3.2±0.5kg (6.1±0.9%) of lean mass; and 0.48±0.07kg (18.7±2.7%) of BMC. Significant negative relationships were found between head% versus whole-body BMC (r=-0.54;p < 0.0001), lean mass (r=-0.57;p<0.0001), and fat mass (r=-0.81;p<0.0001) and between feet% versus fat mass (r=-0.68;p<0.0001). A significant positive relationship was noted between feet% versus whole-body BMC (r=0.18;p=0.04) but not versus lean mass (r=0.15;p=0.09). Removing the feet from whole-body composition analyses reduces lean, fat and bone mass compartment totals by 3%-5%. Removing the head region reduces body composition compartments by 6%-19%, from whole-body DXA scan totals.

Pandemic-Induced Reductions on Swim Training Volume and Performance in Collegiate Swimmers.

The COVID-19 pandemic caused significant training disruptions during the 2020-2021 season, due to lockdowns, quarantines, and strict adherence to the pandemic protocols. The main purpose of this study was to determine how the pandemic training restrictions affected training volume and performance in one collegiate swim team. Cumulative training volume data across a 28-week season were compared between a pandemic (2020-2021) versus non-pandemic (2019-2020) season. The swimmers were categorized into three groups (sprinters, mid-distance, and long-distance) based on their training group. The performance times of 25 swimmers who competed in the regional championships, during both the non-pandemic and pandemic year, were compared via one-way ANOVA. Twenty-six male and 22 female swimmers commenced the 2020-2021 (pandemic) season, with 23% of the swimmers voluntarily opting out. Three COVID-19 cases were confirmed (2%) by the medical staff, with no long-term effects. Significant reductions in the average swim volume were verified in sprinters (32,867 ± 10,135 vs. 14,800 ± 7995 yards; p < 0.001), mid-distance (26,457 ± 10,692 vs. 17,054 ± 9.923 yards; p < 0.001), and long-distance (37,600 ± 14,430 vs. 22,254 ± 14,418 yards; p < 0.001) swimmers (non-pandemic vs. pandemic season, respectively). In the regional performance analyses, the sprinters swam faster (n = 8; -0.5 ± 0.6 s), while the mid-distance (n = 10; 0.17 ± 2.1 s) and long-distance (n = 7; 6.0 ± 4.9 s) swimmers swam slower (F = 11.76; p = 0.0003; r2 = 0.52). Thus, the pandemic caused significant reductions in swim training volume, with sprinters performing better and long-distance swimmers performing worse at the regional championships.

Of Mice and Men-The Physiology, Psychology, and Pathology of Overhydration.

The detrimental effects of dehydration, to both mental and physical health, are well-described. The potential adverse consequences of overhydration, however, are less understood. The difficulty for most humans to routinely ingest ≥2 liters (L)-or "eight glasses"-of water per day highlights the likely presence of an inhibitory neural circuit which limits the deleterious consequences of overdrinking in mammals but can be consciously overridden in humans. This review summarizes the existing data obtained from both animal (mostly rodent) and human studies regarding the physiology, psychology, and pathology of overhydration. The physiology section will highlight the molecular strength and significance of aquaporin-2 (AQP2) water channel downregulation, in response to chronic anti-diuretic hormone suppression. Absence of the anti-diuretic hormone, arginine vasopressin (AVP), facilitates copious free water urinary excretion (polyuria) in equal volumes to polydipsia to maintain plasma tonicity within normal physiological limits. The psychology section will highlight reasons why humans and rodents may volitionally overdrink, likely in response to anxiety or social isolation whereas polydipsia triggers mesolimbic reward pathways. Lastly, the potential acute (water intoxication) and chronic (urinary bladder distension, ureter dilation and hydronephrosis) pathologies associated with overhydration will be examined largely from the perspective of human case reports and early animal trials.