Fluid Intake and Hydration Responses to Mass Participation Gravel Cycling

Gravel cycling is a relatively new cycling discipline, with the Union Cycliste Internationale (UCI) hosting their first UCI Gravel World Championships in 2022. Gravel races combine features of road racing, cyclocross, and mountain biking, including various terrain of varying technical difficulty (paved roads, dirt roads, fire roads, single- and double-track trails), long distances, substantial vertical elevation gain, obstacles, and limited opportunities to stop for in-race nutrition. PURPOSE: To date, gravel racing has not been scientifically examined to determine the demands of the sport. Data from cycling road races indicate substantial fluid loss, which may impair exercise performance. This study assessed hydration responses to gravel races of three different distances. METHODS: This field study collected data on saliva osmolarity, body mass, fluid intake, and nutrition knowledge. Variables were assessed before and after a gravel cycling race in April 2023. A total of 121 participants completed pre-race surveys, 53 provided pre-race measures of body mass and saliva osmolarity (SOsm), and 38 participants completed post-race testing. RESULTS: Based on manufacturer cutpoints for SOsm, only 22.6% (n = 12) of participants were hydrated before the race, with 56.6% mildly dehydrated (n = 30), 18.9% moderately dehydrated (n = 10), and 1.9% severely dehydrated (n = 1). Post-race, 15% (n=6) were still hydrated, 20% (n = 8) were mildly dehydrated, 47.5% (n = 19) were moderately dehydrated, and 17.5% (n = 7) were severely dehydrated. Analyses revealed significant decreases in body mass and increases in SOsm from pre- to post-exercise in the two longer race distances (p \u3c 0.05). There was a significant effect of race distance on energy, fluid, carbohydrate, and sodium intake (p \u3c 0.05), but post-hoc comparisons were only significant for fluid intake. Sweat rates were not different (p \u3e 0.05). Change in percent body mass and change in SOsm were not correlated (r = -0.254, p = 0.118). Longer race distances were associated with higher energy, fluid, carbohydrate, and sodium intake. CONCLUSION: This study provides data quantifying the fluid and nutrient intake during mass participation gravel cycling. Future studies should expand on our results by capturing in-race nutrient data and more sensitive hydration assessments

Validity of a Novel Sensor for Noninvasive Measurement of Core Body Temperature in Humans during Exercise

The measurement of core body temperature during exercise can be useful for athletic performance and the prevention of heat-related illness. Non-invasive sensors have been developed for the measurement of core body temperature, but more data on their validity and reliability is needed before they can be recommended for widespread adoption. PURPOSE: The purpose of the present study was to evaluate a noninvasive core temperature sensor (TCore) during exercise compared to an ingestible thermistor (TPill). METHODS: Twenty men and women (25 ± 4 years) participated in this study. Participants completed 20 minutes of exercise at 60% age-predicted max heart rate, 20 minutes at 70%, and 20 minutes at 80% while wearing warm clothing. During exercise, heart rate, core temperature, RPE, and thermal comfort were collected every 5 minutes. Pre/post exercise changes in body mass and urine specific gravity were conducted to ensure stable fluid levels. Mean differences were compared via a paired t-test, core temperature during exercise using a time*device repeated measures ANOVA, and agreement assessed with Bland-Altman and correlation analysis. RESULTS: Participants lost -0.47 ± 0.42 % body mass during exercise. USG did not change in response to exercise (Pre: 1.009 ± 0.005 vs Post: 1.009 ± 0.006; p =0.93). Devices were well correlated (r = 0.90, 95% Confidence Interval: 0.74 – 0.97; p \u3c 0.0001). Mean core temperature during exercise was slightly but significantly lower as measured by the TCore compared to TPill (Mean difference = -0.3°C, 95% CI: -0.57 to -0.03; p = 0.028). Exercise created a main effect of time on core temperature (p \u3c 0.0001), with a significant interaction across time between devices (p \u3c 0.0001). Specifically, core temperature was lower for TCore from 15-55 minutes of exercise compared to TPill. Mean ± SD of bias was -0.3°C ± 0.16, with 95% limits of agreement of -0.61°C to 0.03°C. CONCLUSION: Results of the present investigation revealed that the CORE device tended to underestimate core body temperature during indoor exercise of increasing intensity. However, the margin of error was relatively small, and few participants exceeded 39°C. Future studies should conduct field validity tests of the CORE device and should also include measures of skin temperature to facilitate further comparisons

Influence of Acute Exercise on Postprandial Lipemia and Fat Oxidation in Active Cannabis Users

Adults residing in industrialized nations spend most of their day in a postprandial state. This can cause prolonged elevated levels of triglycerides and glucose post-meal, leading to increased risk of cardiovascular and metabolic disease. In epidemiological literature, cannabis users have been reported to have similar or lower levels of blood lipids compared to nonusers. However, postprandial responses and whether prior exercise improves postprandial lipemia (PPL) in this population is not known. PURPOSE: To examine the influence of prior exercise on PPL in active cannabis users. METHODS: This analysis presents preliminary data from a larger ongoing study comparing prior exercise and PPL in cannabis users and non-users. Seven active cannabis users (Age: 30 ± 7 years; BMI: 24.3 ± 3.4 kg/m2; VO2max: 47.5 ± 10.8 mL/kg/min) completed 1 hour of exercise at their ventilatory threshold (VT) the evening before a high-fat, high-sugar liquid meal containing 15 kcal/kg body mass. Substrate oxidation, blood pressure, and capillary blood samples were obtained before and every 30-60 minutes post-meal for 3 hours. Blood samples were analyzed for glucose and triglycerides. Repeated-measures ANOVAs were utilized to examine differences in variables between conditions, across time, and their interaction. Area-under-the-curve (AUC) for glucose and triglycerides were calculated by the trapezoidal rule. RESULTS: Participants exercised at an intensity of 96 ± 5% VT (73 ± 11% VO2max) and expended 790 ± 168 kcals with an average RER of 0.92 ± 0.03. Post meal (1141 ± 200 kcals), all variables had significant effects of time (p \u3c 0.05), but no significant effect of condition (Control vs. Exercise) or interaction (p \u3e 0.05). AUC for triglycerides (p = 0.057) and glucose (p = 0.243) were not significantly different between conditions. CONCLUSION: In the present analysis, exercise did not acutely affect cardiovascular or metabolic responses to a high-fat, high-sugar liquid meal. Larger sample sizes will facilitate better comparisons

The Hydration Status of Female Collegiate Soccer Players Over Consecutive Training and Match Days

Purpose: Hydration has been shown to play a pivotal role in sport. Soccer is a team sport in which the integrity of all players is vital for team performance; thus, individual player hydration status is important. The primary aim of this study was to investigate the hydration status of female collegiate soccer players during regular season. Methods: Sixteen collegiate female soccer players (age: 20.4 ± 0.8 years; height: 163.6 ± 6.9 cm; weight: 65.3 ± 12 kg) provided urine over 9 days to monitor their hydration status. Hydration was determined by urine specific gravity (Usg). Usg was analyzed in the morning (AM) and in the afternoon before practice/game (PM). Results: All 16 players were at least minimally hypohydrated (Usg \u3e 1.010) in the AM on 5 of the 9 days tested. Players had significantly higher Usg values in the AM as compared to PM (F(1,250) = 23.09; p \u3c 0.0001); however, there was no significant time*day interaction (F(1,250) = 1.98; p = 0.16). Conclusion: Data show a high prevalence of hypohydration occurring in this specific population. This sub-optimal hydration status could be a cause for concern in terms of overall performance. Efforts should be made to integrate hydration interventions and daily monitoring to minimize hypohydration in players

The Hydration Status of Female Collegiate Soccer Players Over Consecutive Training and Match Days

Purpose: Hydration has been shown to play a pivotal role in sport. Soccer is a team sport in which the integrity of all players is vital for team performance; thus, individual player hydration status is important. The primary aim of this study was to investigate the hydration status of female collegiate soccer players during regular season. Methods: Sixteen collegiate female soccer players (age: 20.4 ± 0.8 years; height: 163.6 ± 6.9 cm; weight: 65.3 ± 12 kg) provided urine over 9 days to monitor their hydration status. Hydration was determined by urine specific gravity (Usg). Usg was analyzed in the morning (AM) and in the afternoon before practice/game (PM). Results: All 16 players were at least minimally hypohydrated (Usg \u3e 1.010) in the AM on 5 of the 9 days tested. Players had significantly higher Usg values in the AM as compared to PM (F(1,250) = 23.09; p \u3c 0.0001); however, there was no significant time*day interaction (F(1,250) = 1.98; p = 0.16). Conclusion: Data show a high prevalence of hypohydration occurring in this specific population. This sub-optimal hydration status could be a cause for concern in terms of overall performance. Efforts should be made to integrate hydration interventions and daily monitoring to minimize hypohydration in players

Band-to-band transitions and critical points in the near-infrared to vacuum ultraviolet dielectric functions of single crystal urania and thoria

Band-to-band transition energy parameters for single-crystal actinide samples of uranium oxide and thorium oxide were determined and compared using spectroscopic ellipsometry and critical-point dielectric function analyses. Spectroscopic ellipsometry measurements from the near-infrared to the vacuum ultraviolet spectral region were used to determine the dielectric functions of uranium oxide and thorium oxide. The critical-point structure is similar between UO2 and ThO2 but strongly blue shifted for ThO2. We find bandgap energies of 2.1 eV and 5.4 eV for UO2 and ThO2, respectively

Infrared-active Phonon Modes in Single-crystal Thorium Dioxide and Uranium Dioxide

The infrared-active phonon modes, in single-crystal samples of thorium dioxide (ThO2) and uranium dioxide (UO2), were investigated using spectroscopic ellipsometry and compared with density functional theory. Both ThO2 and UO2 are found to have one infrared-active phonon mode pair [consisting of one transverse optic (TO) and one associated longitudinal optic (LO) mode], which is responsible for the dominant features in the ellipsometric data. At room temperature, our results for the mode pair’s resonant frequencies and broadening parameters are comparable with previous reflectance spectroscopy characterizations and density functional theory predictions. For ThO2, our ellipsometry and density function theory results both show that the LO mode broadening parameter is larger than the TO mode broadening. This signifies mode anharmonicity, which can be attributed to the intrinsic phonon–phonon interaction. In addition to the main mode pair, a broad low-amplitude impurity-like vibrational mode pair is detected within the reststrahlen band for both ThO2 and UO2. Elevated temperature measurements were performed for ThO2 in order to study the mechanisms by which the phonon parameters evolve with increased heat. The observed change in the TO resonant frequency is in excellent agreement with previous density functional calculations, which only consider volume expansion of the crystal lattice. This suggests that the temperature-dependent change in the TO frequency is primarily due to volume expansion. The change in the main mode pair’s broadening parameters is nearly linear within the temperature range of this study, which indicates the intrinsic anharmonic scattering (via cubic anharmonicities) as the main decay mechanism

Band-to-band Transitions and Critical Points in the Near-infrared to Vacuum Ultraviolet Dielectric Functions of Single Crystal Urania and Thoria

Band-to-band transition energy parameters for single-crystal actinide samples of uranium oxide and thorium oxide were determined and compared using spectroscopic ellipsometry and critical-point dielectric function analyses. Spectroscopic ellipsometry measurements from the near-infrared to the vacuum ultraviolet spectral region were used to determine the dielectric functions of uranium oxide and thorium oxide. The critical-point structure is similar between UO2 and ThO2 but strongly blue shifted for ThO2. We find bandgap energies of 2.1 eV and 5.4 eV for UO2 and ThO2, respectively

Telepresence and the Role of the Senses

The telepresence experience can be evoked in a number of ways. A well-known example is a player of videogames who reports about a telepresence experience, a subjective experience of being in one place or environment, even when physically situated in another place. In this paper we set the phenomenon of telepresence into a theoretical framework. As people react subjectively to stimuli from telepresence, empirical studies can give more evidence about the phenomenon. Thus, our contribution is to bridge the theoretical with the empirical. We discuss theories of perception with an emphasis on Heidegger, Merleau-Ponty and Gibson, the role of the senses and the Spinozian belief procedure. The aim is to contribute to our understanding of this phenomenon. A telepresence-study that included the affordance concept is used to empirically study how players report sense-reactions to virtual sightseeing in two cities. We investigate and explore the interplay of the philosophical and the empirical. The findings indicate that it is not only the visual sense that plays a role in this experience, but all senses