Gastrointestinal (GI) disturbances are a prevalent cause of marathon related complaints, and in extreme cases can promote life-threatening conditions such as exertional heat stroke. Our aim was to ...study intestinal cell injury via intestinal fatty acid binding protein (I-FABP) and perceived GI distress symptoms among marathon runners. We also examined potential risk factors (e.g., inadequate sleep) that could exacerbate GI disturbances in healthy, trained endurance runners. This was a parallel mixed-methods study design. 2019 Boston Marathon participants were recruited via email and subjects completed surveys before the race describing demographics and training history. Participants completed a GI questionnaire to assess presence and severity of symptoms, a survey regarding risk factors (e.g., recent illness, medications) that could promote GI disturbances, and provided a urine sample at three time points (immediately pre-race, post-race, and 24-h post-race). Due to weather, blood samples were only collected immediately and 24-h post-race. A total of 40 runners (males:
n
= 19, age = 44.9 ± 10.8 years; females: n = 21, age = 44.8 ± 10.6 years) completed this study. I-FABP significantly decreased from post-race (3367.5 ± 2633.5 pg/mL) to 24-h post-race (1657.3 ± 950.7 pg/mL, t (39) = −4.228,
p
< .001, d = −.669). There was a significant difference in overall GI symptom scores across the three time points (F (2, 39) = 41.37,
p
< .001). The highest average score occurred post-race (.84 ± .68), compared to pre-race (.09 ± .12) and 24-h post-race (.44 ± .28). Post-race I-FABP (r = .31,
p
= .048) and post-race urine specific gravity (r = .33,
p
= .041) were significantly correlated with post-race GI symptom scores. Our study provides further support to the individualized nature of GI disturbances, with participants experiencing a wide range of risk factors that can influence the extent of GI damage and perceived symptoms during and after exercise.
Evaluate physiological and perceptual responses using a phase change cooling (PCC) garment during simulated work in the heat.
Twenty males wearing compression undergarments, coverall suit, gloves, ...and hard-hat, completed two randomly assigned trials (with PCC inserts or control, CON) of simulated industrial tasks in the heat (34.2 ± 0.05 °C, 54.7 ± 0.3%RH). Trials consisted of two 20 min work bouts, a maximum performance bout, and 10 min of recovery.
Physiological strain index (PSI) was lower during PCC after the second work bout and during recovery (all P < 0.05). PCC reduced heat storage (27.0 ± 7.6 W m−2) compared to CON (42.7 ± 9.9 W m−2, P < 0.001). Perceptual strain index (PeSI) was reduced with PCC compared to CON (P < 0.001), however performance outcomes were not different between trials (P = 0.10).
PCC during work in the heat attenuated thermal, physiological, and perceptual strain. This PCC garment could increase safety and reduce occupational heat illness risk.
•Phase change cooling was used during simulated industrial work in the heat.•Physiological strain during work and recovery decreased with phase change cooling.•Phase change cooling improved perceptual responses to work in the heat.•Work performance was not improved with the use of phase change cooling.
The purpose of our field study was to investigate the effects of running the Boston Marathon on acute kidney injury (AKI) biomarkers. We hypothesized that biomarker values would be elevated ...immediately post-marathon but would resolve in the 24-h post-marathon. Secondarily, we sought to identify sex differences related to renal stress. Participants were 65 runners who completed the Boston Marathon (46 ± 9 years, 65.4 ± 10.8 kg). Urine samples were collected at three different time points (pre-marathon, post-marathon, and 24-h post-marathon). Blood samples were collected post-marathon and 24-h post-marathon. Urine specific gravity (USG) and AKI biomarkers were evaluated. Pre-marathon USG (1.012 ± 0.007) was significantly less than post-marathon (1.018 ± 0.008) and 24-h post-marathon (1.020 ± 0.009;
< 0.001). Male USG (1.024 ± 0.009) was significantly greater 24-h post-marathon than females (1.017 ± 0.008;
= 0.019). Urinary neutrophil gelatinase-associated lipocalin values were significantly greater over time (
< 0.001), and there was a main effect of sex with female urinary creatinine (
Cr) greater than males at all three time points (
= 0.040). Post-marathon
Cr (366.24 ± 295.16 mg/dl) was significantly greater than pre-marathon (206.65 ± 145.28.56 mg/dl;
< 0.001) and 24-h post-marathon was significantly lower than other time-points (93.90 ± 125.07 mg/dl;
< 0.001). Female
Cr values were significantly greater than males 24-h post-marathon (
< 0.001). There was no difference in serum cystatin C (
Cys) values post- or 24-h post-marathon (
= 0.178). Serum creatinine (
Cr) significantly decreased between post-marathon and 24-h post-marathon, (
< 0.001). We can infer that the characteristics unique to the Boston Marathon may have attributed to prolonged elevations in AKI biomarkers. Sex differences were observed during the Boston Marathon warranting further investigation.
Purpose
This study determined fluid intake and physical activity behaviors among college students during the COVID-19 pandemic.
Methods
College students (
n
= 1014; females, 75.6%) completed an ...online survey during the Spring 2020 academic semester following the initial global response to the COVID-19 pandemic. Academic standing, habitation situation, and University/College responses to COVID-19 were collected. Participants completed the Godin Leisure-Time Exercise Questionnaire and a 15-item Beverage Questionnaire (BEVQ-15) to determine physical activity level and fluid intake behaviors, respectively.
Results
Females (1920 ± 960 mL) consumed significantly less fluid than males (2400 ± 1270 mL,
p
< 0.001). Living off-campus (
p
< 0.01) and living with a spouse/partner (
p
< 0.01) was associated with increased consumption of alcoholic beverages. 88.7% of participants reported being at least moderately active; however, Black/African American and Asian participants were more likely to be less active than their Caucasian/White counterparts (
p
< 0.05). Participants reporting no change in habitation in response to COVID-19 had a higher fluid intake (
p
= 0.002); however, the plain water consumption remained consistent (
p
= 0.116). While there was no effect of habitation or suspension of classes on physical activity levels (
p
> 0.05), greater self-reported physical activity was associated with greater fluid intake (std. β = 0.091,
p
= 0.003).
Conclusions
Fluid intake among college students during the initial response to the COVID-19 pandemic approximated current daily fluid intake recommendations. Associations between COVID-19-related disruptions (i.e., suspension of classes and changes in habitation) and increased alcohol intake are concerning and may suggest the need for the development of targeted strategies and programming to attenuate the execution of negative health-related behaviors in college students.
•People of larger body size drink more water.•Body size is correlated with urine osmolality.•Overweight and obese individuals may have a dysregulated thirst mechanism.
Elevated body mass index (BMI) ...has been associated with elevated urine osmolality (UOsm), despite having higher total water intake, but it is unclear if overweight/obese individuals have reduced thirst. In this observational study, we found that overweight/obese individuals had higher UOsm compared to normal-weight individuals (749 ± 37 vs. 624 ± 35 mmol•kg−1; P < 0.01) while possessing similar thirst ratings (56.4 ± 3 vs. 51.6 ± 3 mm; P = 0.3). In this observational study, overweight/obese individuals possessed more concentrated urine in the absence of higher thirst perception.
ABSTRACTPaulsen, KM, Butts, CL, and McDermott, BP. Observation of women soccer playersʼ physiology during a single season. J Strength Cond Res 32(6)1702–1707, 2018—The purpose of this study was to ...observe heart rate (HR) responses in match settings over the course of a conference season in National Collegiate Athletic Association Division I womenʼs soccer. Twenty-one female collegiate soccer players were provided a HR monitor and instructed to wear it for the duration of match play. Player positions included 6 defenders (DEF), 6 midfielders (MID), and 9 forwards (FWD). Defenders were further identified as either center defenders (CD) or outside defenders (OD). A 1-way analysis of variance was used to determine if mean HR varied between FWD, MID, and DEF. An independent t-test was used to determine if there was a difference between CD and OD HRs. The FWD, MID, and DEF did have significantly different mean HR (p ≤ 0.05), but post-hoc analysis revealed no significant differences (p ≥ 0.05). However, CD demonstrated significantly lower HRs than OD (p = 0.009). Player position, specifically in the CD and OD role, impact the intensity of exercise in match settings and may be used to specify training and conditioning sessions.
Objective: Prior research suggests maximal physical exertion (MPE) may negatively affect the reliability and validity of computerized neurocognitive testing (CNT); the purpose of this study was to ...identify aclinically relevant recovery interval following MPE for the administration of baseline CNT.
Design: Random-crossover.
Participants: Thirty (M = 21.87 ± 2.29 y), moderately-active,healthy participants, without history of ADHD, learning disabilities, psychological disorders or concussion (within the last six months).
Intervention: Participants completed four randomly ordered experimental trials. Except for the control trial, CNT was administered following MPE with assigned recovery intervals Immediate, 10-minutes,or 20-minutes. Aseries of repeated measures analysis of variance (ANOVAs) were performed on CNT composite and total symptom scores.
Results: Total symptom scores were significantly greater (p < .01) at the immediate, 10-minute,and 20-minuterecovery intervals compared to the control trial. Processing speed was significantly faster at the 20-minuterecovery interval compared to the control trials. Visual memory, verbal memory, or reaction time did not differ across recovery intervals.
Conclusions: Clinicians should wait more than 20 minutes before assessing baseline concussion symptoms following about of MPE.
Epidemiological studies in humans show increased concentrations of copeptin, a surrogate marker of arginine vasopressin (AVP), to be associated with increased risk for type 2 diabetes.
To examine the ...acute and independent effect of osmotically stimulated AVP, measured via the surrogate marker copeptin, on glucose regulation in healthy adults.
Sixty subjects (30 females) participated in this crossover design study. On 2 trial days, separated by ≥7 d (males) or 1 menstrual cycle (females), subjects were infused for 120 min with either 0.9% NaCl isotonic (ISO) or 3.0% NaCl hypertonic (HYPER). Postinfusion, a 240-min oral-glucose-tolerance test (OGTT; 75 g) was administered.
During HYPER, plasma osmolality and copeptin increased (P < 0.05) and remained elevated during the entire 6-h protocol, whereas renin-angiotensin-aldosterone system hormones were within the lower normal physiological range at the beginning of the protocol and declined following infusion. Fasting plasma glucose did not differ between trials (P > 0.05) at baseline and during the 120 min of infusion. During the OGTT the incremental AUC for glucose from postinfusion baseline (positive integer) was greater during HYPER (401.5 ± 190.5 mmol/L·min) compared with the ISO trial (354.0 ± 205.8 mmol/L·min; P < 0.05). The positive integer of the AUC for insulin during OGTT did not differ between trials (HYPER 55,850 ± 36,488 pmol/L·min compared with ISO 57,205 ± 31,119 pmol/L·min). Baseline values of serum glucagon were not different between the 2 trials; however, the AUC of glucagon during the OGTT was also significantly greater in HYPER (19,303 ± 3939 ng/L·min) compared with the ISO trial (18,600 ± 3755 ng/L·min; P < 0.05).
The present data indicate that acute osmotic stimulation of copeptin induced greater hyperglycemic responses during the oral glucose challenge, possibly due to greater glucagon concentrations.
This study was registered at clinicaltrials.gov as NCT02761434.
Purpose
Prior evidence indicates that acute heat stress and aerobic exercise independently reduce arterial stiffness. The combined effects of exercise and heat stress on PWV are unknown. The purpose ...of this study was to determine the effects of heat stress with passive heating and exercise in the heat on arterial stiffness.
Methods
Nine participants (
n
= 3 females, 47 ± 11 years old; 24.1 ± 2.8 kg/m
2
) completed four trials. In a control trial, participants rested supine (CON). In a passive heating trial (PH), participants were heated with a water-perfusion suit. In two other trials, participants cycled at ~50% of
V
˙
O
2
peak
in a hot (~40 °C; HC trial) or cool (~15 °C; CC trial) environment. Arterial stiffness, measured by PWV, was obtained at baseline and after each intervention (immediately, 15, 30, 45, and 60 min post). Central PWV (
C
PWV
) was assessed between the carotid/femoral artery sites. Upper and lower peripheral PWV was assessed using the radial/carotid (
U
PWV
) and dorsalis pedis/femoral (
L
PWV
) artery sites. The mean body temperature (
T
B
) was calculated from the skin and rectal temperatures.
Results
No significant changes in
T
B
were observed during the CON and CC trials. As expected, the PH and HC trials elevated
T
B
2.69 ± 0.23 °C and 1.67 ± 0.27 °C, respectively (
p
< 0.01). PWV did not change in CON, CC, or HC (
p
> 0.05). However, in the PH trial,
U
PWV
was reduced immediately (−107 ± 81 cm/s) and 15 min (−93 ± 82 cm/s) post-heating (
p
< 0.05).
Conclusions
Heat stress via exercise in the heat does not acutely change arterial stiffness. However, passive heating reduces
U
PWV
, indicating that heat stress has an independent effect on PWV.
Whole body heat stress (WBH) results in numerous cardiovascular alterations that ultimately reduce orthostatic tolerance. While impaired carotid baroreflex (CBR) function during WBH has been reported ...as a potential reason for this decrement, study design considerations may limit interpretation of previous findings. We sought to test the hypothesis that CBR function is unaltered during WBH. CBR function was assessed in 10 healthy male subjects (age: 26 ± 3; height: 185 ± 7 cm; weight: 82 ± 10 kg; BMI: 24 ± 3 kg/m
; means ± SD) using 5-s trials of neck pressure (+45, +30, and +15 Torr) and neck suction (-20, -40, -60, and -80 Torr) during normothermia (NT) and passive WBH (Δ core temp ∼1°C). Analyses of stimulus response curves (four-parameter logistic model) for CBR control of heart rate (CBR-HR) and mean arterial pressure (CBR-MAP), as well as separate two-way ANOVA of the hypotensive and hypertensive stimuli (factor 1: thermal condition, factor 2: chamber pressure), were performed. For CBR-HR, maximal gain was increased during WBH (-0.73 ± 0.11) compared with NT (-0.39 ± 0.04, mean ± SE,
= 0.03). In addition, the CBR-HR responding range was increased during WBH (33 ± 5) compared with NT (19 ± 2 bpm,
= 0.03). Separate analysis of hypertensive stimulation revealed enhanced HR responses during WBH at -40, -60, and -80 Torr (condition × chamber pressure interaction,
= 0.049) compared with NT. For CBR-MAP, both logistic analysis and separate two-way ANOVA revealed no differences during WBH. Therefore, in response to passive WBH, CBR control of heart rate (enhanced) and arterial pressure (no change) is well preserved.
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