Blood and MRI biomarkers of mild traumatic brain injury in non-concussed collegiate football players.

Football has one of the highest incidence rates of mild traumatic brain injury (mTBI) among contact sports; however, the effects of repeated sub-concussive head impacts on brain structure and function remain under-studied. We assessed the association between biomarkers of mTBI and structural and functional MRI scans over an entire season among non-concussed NCAA Division I linemen and non-linemen. Concentrations of S100B, GFAP, BDNF, NFL, and NSE were assessed in 48 collegiate football players (32 linemen; 16 non-linemen) before the start of pre-season training (pre-camp), at the end of pre-season training (pre-season), and at the end of the competitive season (post-season). Changes in brain structure and function were assessed in a sub-sample of 11 linemen and 6 non-linemen using structural and functional MRI during the execution of Stroop and attention network tasks. S100B, GFAP and BDNF concentrations were increased at post-season compared to pre-camp in linemen. White matter hyperintensities increased in linemen during pre-season camp training compared to pre-camp. This study showed that the effects of repeated head impacts are detectable in the blood of elite level non-concussed collegiate football players exposed to low-moderate impacts to the heads, which correlated with some neurological outcomes without translating to clinically-relevant changes in brain anatomy or function.

Seasonal changes in physiological and psychological parameters of stress in collegiate swimmers.

To investigate the seasonal changes in physiological and psychological parameters of stress in collegiate swimmers. Fifteen NCAA Division I swimmers (8 men) participated in a tethered anaerobic swim test to determine physiological responses in an ecologically-relevant, graded exercise test. Wisconsin Upper Respiratory Symptom Survey (WURSS-21), Activation-Deactivation Adjective Check List (AD-ACL), Daily Analysis of Life Demands of Athletes (DALDA), and Pittsburgh Sleep Quality Index were assessed at post-season in April (V1), the end of off-season in June (V2), and pre-season in October (V3). The percent change was determined from V2-V1 (off-season phase), V3-V2 (pre-season phase), V1-V3 (in-season phase). Spearman's rho correlation was used to examine associations between change in physiological and psychological outcomes. All data results showed a better swim performance occurred at V2. Men tended to have faster speed (p = 0.07) in fewer strokes (p = 0.10) and greater work per stroke (p = 0.10) at V2 than V1. Women were faster during V2 compared to V1 (p = 0.02) and V3 (p = 0.05). Women had fewer strokes (p = 0.02) and greater work per stroke (p = 0.01) at V2 compared to V3. Women had the lowest HR and lactate concentration at V3 compared to other visits (p < 0.05). During the in-season phase, swim speed decreased the greatest extent and stress sources and symptoms assessed by DALDA had greatest elevation (p < 0.05). An increased in stress sources and symptoms assessed by DALDA was associated with an increase in upper respiratory illness from WURSS-21 (rho = 0.44, p = 0.009), being less energetic (rho = - 0.35, p = 0.04) and greater tension state (rho = 0.49, p = 0.003; AD-ACL), and a decrease in swim speed (rho =- 0.38, p = 0.03). Swim performance peaked at off-season when psychological stress was at its lowest. The relationship between DALDA scores with psychological parameters and swim performance suggested physiological and psychological parameters of stress is an important aspect to avoid overtraining when approaching high swim performance.

Impact of maximal exercise on immune cell mobilization and bioenergetics.

Acute aerobic exercise increases the number and proportions of circulating peripheral blood mononuclear cells (PMBC) and can alter PBMC mitochondrial bioenergetics. In this study, we aimed to examine the impact of a maximal exercise bout on immune cell metabolism in collegiate swimmers. Eleven (7 M/4F) collegiate swimmers completed a maximal exercise test to measure anaerobic power and capacity. Pre- and postexercise PBMCs were isolated to measure the immune cell phenotypes and mitochondrial bioenergetics using flow cytometry and high-resolution respirometry. The maximal exercise bout increased circulating levels of PBMCs, particularly in central memory (KLRG1+/CD57-) and senescent (KLRG1+/CD57+) CD8+ T cells, whether measured as a % of PMBCs or as absolute concentrations (all p < 0.05). At the cellularlevel, the routine oxygen flow (IO2 [pmol·s-1 ·106 PBMCs-1 ]) increased following maximal exercise (p = 0.042); however, there were no effects of exercise on the IO2 measured under the LEAK, oxidative phosphorylation (OXPHOS), or electron transfer (ET) capacities. There were exercise-induced increases in the tissue-level oxygen flow (IO2-tissue [pmol·s-1 ·mL blood-1 ]) for all respiratory states (all p < 0.01), except for the LEAK state, after accounting for the mobilization of PBMCs. Future subtype-specific studies are needed to characterize further maximal exercise's true impact on immune cell bioenergetics.

Impact of acute exercise on peripheral blood mononuclear cells nutrient sensing and mitochondrial oxidative capacity in healthy young adults.

Regular exercise is associated with changes in peripheral blood mononuclear cell (PBMC) proportions that have enhanced effector functions in young and old adults; however, the effects of acute exercise on PBMC nutrient sensors and metabolic function in active young adults is unknown. To fill this gap, activation status and nutrient-sensing mechanisms of PBMCs isolated from 21 healthy active adults (20-35 yr; 36.5 ± 6.3 V̇O2peak ) were characterized before and after 30 min of moderate-to-vigorous cycling (65%-75% V̇O2peak ). In addition, changes in PBMC mitochondrial respiratory function in response to exercise were assessed using high-resolution respirometry. There was an increase in the number of activated CD69+/CD4 (79% increase) and CD69+/CD8 (166% increase) T-cells in response to the acute bout of exercise, while the nutrient-sensing mechanisms remained unchanged. PBMC mitochondrial respiration did not increase on a cell-per-cell basis, however, mitochondrial oxidative capacity (OXPHOS) increased at the tissue level (18.6 pmol/(s*ml blood) versus 29.3 pmol/(s*ml blood); p < 0.05) in response to acute exercise. Thus, this study shows that acute exercise preferentially mobilizes activated T-cells while concomitantly increasing PBMC mitochondrial oxidative capacity at the tissue level, rather than acutely changing mitochondrial oxidative capacity at the cellular level in young adults.

Cytomegalovirus Infection Impairs the Mobilization of Tissue-Resident Innate Lymphoid Cells into the Peripheral Blood Compartment in Response to Acute Exercise.

Circulating immune cell numbers and phenotypes are impacted by high-intensity acute bouts of exercise and infection history with the latent herpesviruses cytomegalovirus (CMV). In particular, CMV infection history impairs the exercise-induced mobilization of cytotoxic innate lymphoid cells 1 (ILC1) cells, also known as NK cells, in the blood. However, it remains unknown whether exercise and CMV infection modulate the mobilization of traditionally tissue-resident non-cytotoxic ILCs into the peripheral blood compartment. To address this question, 22 healthy individuals with or without CMV (20-35 years-45% CMVpos) completed 30 min of cycling at 70% VO2 max, and detailed phenotypic analysis of circulating ILCs was performed at rest and immediately post-exercise. We show for the first time that a bout of high-intensity exercise is associated with an influx of ILCs that are traditionally regarded as tissue-resident. In addition, this is the first study to highlight that latent CMV infection blunts the exercise-response of total ILCs and progenitor ILCs (ILCPs). These promising data suggest that acute exercise facilitates the circulation of certain ILC subsets, further advocating for the improvements in health seen with exercise by enhancing cellular mobilization and immunosurveillance, while also highlighting the indirect deleterious effects of CMV infection in healthy adults.

Effects of Field Position on Fluid Balance and Electrolyte Losses in Collegiate Women's Soccer Players.

Research investigating hydration strategies specialized for women's soccer players is limited, despite the growth in the sport. The purpose of this study was to determine the effects of fluid balance and electrolyte losses in collegiate women's soccer players. Eighteen NCAA Division I women's soccer players were recruited (age: 19.2 ± 1.0 yr; weight: 68.5 ± 9.0 kg, and height: 168.4 ± 6.7 cm; mean ± SD), including: 3 forwards (FW), 7 mid-fielders (MD), 5 defenders (DF), and 3 goalkeepers (GK). Players practiced outdoor during spring off-season training camp for a total 14 practices (WBGT: 18.3 ± 3.1 °C). The main outcome measures included body mass change (BMC), sweat rate, urine and sweat electrolyte concentrations, and fluid intake. Results were analyzed for comparison between low (LOW; 16.2 ± 2.6° C, n = 7) and moderate risk environments for hyperthermia (MOD; 20.5 ± 1.5 °C, n = 7) as well as by field position. The majority (54%) of players were in a hypohydrated state prior to practice. Overall, 26.7% of players had a %BMC greater than 0%, 71.4% of players had a %BMC less than -2%, and 1.9% of players had a %BMC greater than -2% (all MD position). Mean %BMC and sweat rate in all environmental conditions were -0.4 ± 0.4 kg (-0.5 ± 0.6% body mass) and 1.03 ± 0.21 mg·cm-2·min-1, respectively. In the MOD environment, players exhibited a greater sweat rate (1.07 ± 0.22 mg·cm-2·min-1) compared to LOW (0.99 ± 0.22 mg·cm-2·min-1; p = 0.02). By position, DF had a greater total fluid intake and a lower %BMC compared to FW, MD, and GK (all p < 0.001). FW had a greater sweat sodium (Na+) (51.4 ± 9.8 mmol·L-1), whereas GK had the lowest sweat sodium (Na+) (30.9 ± 3.9 mmol·L-1). Hydration strategies should target pre-practice to ensure players are adequately hydrated. Environments deemed to be of moderate risk of hyperthermia significantly elevated the sweat rate but did not influence fluid intake and hydration status compared to low-risk environments. Given the differences in fluid balance and sweat responses, recommendations should be issued relative to soccer position.

Allostatic stress load and CMV serostatus impact immune response to maximal exercise in collegiate swimmers.

Collegiate athletes are exposed to varying levels of academic and physical stressors, placing them at increased risk for stress-activated latent viral infections. However, the impact of allostatic stress load on the immune response to maximal exercise in athletes remains largely unknown. This study examined the effects of a 7-mo training period and cytomegalovirus (CMV) serostatus on immune cell response to high-intensity swim tests within a group of collegiate swimmers. Samples were collected from 15 National Collegiate Athletic Association Division I swimmers (9 men, 6 women: 19.87 ± 0.64 yr) before and after exhaustive in-pool swims at 2 time points (V1: immediately post-season 1 and V3: beginning of season 2). An additional off-season (V2) time point was collected in a subset of 9 swimmers. Natural killer (NK) cell, B cell, and T cells were quantified by flow cytometry. Linear mixed models were used to determine the effects of exercise, time point, and CMV serostatus (α = 0.05). Resting senescent CD8+ T cells were higher in CMV-seropositive participants at V3 (P = 0.005). CMV-seronegative participants had a decrease in resting senescent CD8+ T cells from V1 to V3 (P = 0.021). After acute exercise, CMV-seropositive participants had lower naïve CD8+ T cells (P < 0.001) and higher senescent CD8+ T cells (P < 0.001). Increased cumulative stress levels did not appear to affect B-cell and NK-cell compartments. Immune response to exercise was impacted by CMV serostatus and allostatic stress load. Young CMV-seropositive athletes exposed to elevated stressors should be monitored to determine long-term effects of training and academic stressors.NEW & NOTEWORTHY Allostatic stress load is associated with impaired immune response to maximal exercise in cytomegalovirus (CMV)-seropositive subjects but not in CMV-seronegative young healthy adults.

Free-living, continuous hypo-hydration, and cardiovascular response to exercise in a heated environment.

Chronic dehydration (DEH) and heat stress combined with poor cardiovascular (CV) health may influence physiological responses to exercise. We examined the effects of free-living induced hypo-hydration on physiological responses to exercise in a heated environment and whether resting CV health is related to these changes. Participants (N = 16, 20.6 ± 1.2 years) were randomized to 3 days of voluntary fluid restriction (DEH) or intake (hydration [HYD]) followed by an exercise bout. CV health was assessed by flow-mediated dilation (FMD), pulse wave analysis, and heart rate variability (HRV). HYD was assessed by weight, urine color, and specific gravity (USG). Exercise trials were conducted in a heated environment (30.3 ± 0.8°C, 27.4 ± 7.4% RH) on a cycle ergometer for 30 min. Heart rate (HR), weighted skin (Tsk ) and mean body temperature (Tb ) and skin blood flow (SBF) were assessed during exercise. Pre-exercise weight (P < 0.005), urine color, and USG (P < 0.001) were different in between trials. HR was greater in DEH (153 ± 26 bpm) versus HYD (144 ± 23 bpm, P = 0.02) after exercise. No group differences were found, but a time interaction P < 0.001) for all temperature responses and time-by-trial interaction for Tre (P < 0.01) and Tsk (P < 0.001) was observed. Greater changes in Tre (P = 0.02) and Tsk (P < 0.01) were associated with increased FMD. Free-living, continuous DEH alters weight, blood, and urine markers of HYD as well as HR response during exercise. Resting CV health was related to increased change in Tre and Tsk , suggesting CV health plays a role in the mechanism of heat dissipation when DEH even in college-age men and women.