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We examined the effect of a COVID-19 infection on changes in exercise levels in recreational athletes in the first three months after infection, and identified personal factors associated with a larger change in exercise level and recovery time. Recreational athletes (n=4360) completed an online questionnaire on health and exercise levels. 601 Athletes have had a diagnostically confirmed COVID-19 infection, while 3479 athletes did not (non-COVID-19 group). Exercise levels (in MET-min/week) were examined prior to (2019) and during the COVID-19 pandemic (2020) for the non-COVID-19 group, and in 2019, 1-month pre-COVID-19 infection, 1-month post-COVID-19 infection and 3 months post-COVID-19 infection in the COVID-19 group. Median exercise level at baseline in the COVID-19 group was 3528 (IQR=1488-5760) MET-min/week. One-month post-COVID-19 infection, exercise level dropped 58% (2038 MET-min/week), which partly stabilized to 36% (1256 MET-min/week) below baseline values 3 months post-COVID-19 infection. Moreover, in both the COVID-19 (pre-COVID-19 infection) and non-COVID-19 group exercise levels during the pandemic decreased with ~260 MET-min/week. These results illustrate that even a relatively physically active population of recreational athletes is significantly affected by a COVID-19 infection, particularly those athletes who are overweight. COVID-19 disease burden, age, sex, comorbidities and smoking were not associated with reduced exercise levels.

Item does not contain fulltext PURPOSE: Thermal perception, including thermal sensation (TS), influences exercise performance in the heat. TS is a widely used measure and we examined the impact of initial TS (iTS) on performance loss during exercise in simulated Tokyo environmental conditions among elite athletes. METHODS: 105 Elite outdoor athletes (endurance, skill, power and mixed trained) participated in this crossover study. Participants performed a standardized exercise test in control (15.8 ± 1.2 °C, 55 ± 6% relative humidity (RH)) and simulated Tokyo (31.6 ± 1.0 °C, 74 ± 5% RH) conditions to determine performance loss. TS was assessed ± 5 min prior to exercise (iTS) and every 5 min during the incremental exercise test (TS). Based on iTS in the Tokyo condition, participants were allocated to a neutral (iTS = 0, n = 11), slightly warm (iTS = 1, n = 50), or warm-to-hot (iTS = 2/3, n = 44) subgroup. RESULTS: For the whole cohort iTS was 1 [1-2] and TS increased to 3 [3-3] at the end of exercise in the Tokyo condition. Average performance loss was 26.0 ± 10.7% in the Tokyo versus control condition. The slightly warm subgroup had less performance loss (22.3 ± 11.3%) compared to the warm-to-hot subgroup (29.4 ± 8.5%, p = 0.003), whereas the neutral subgroup did not respond different (28.8 ± 11.0%, p = 0.18) from the slightly warm subgroup. CONCLUSION: iTS impacted the magnitude of performance loss among elite athletes exercising in hot and humid conditions. Athletes with a warm-to-hot iTS had more performance loss compared to counterparts with a slightly warm iTS, indicating that pre-cooling strategies and/or heat acclimation may be of additional importance for athletes in the warm-to-hot iTS group to mitigate the impact of heat stress. 01 februari 2022

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Objective We examined the impact of simulated Tokyo 2020 environmental condition on exercise performance, thermoregulatory responses and thermal perception among Dutch elite athletes. Methods 105 elite athletes from different sport disciplines performed two exercise tests in simulated control (15.9 ± 1.2 °C, relative humidity (RH) 55 ± 6%) and Tokyo (31.6 ± 1.0 °C, RH 74 ± 5%) environmental conditions. Exercise tests consisted of a 20-min warm-up (70% HRmax), followed by an incremental phase until volitional exhaustion (5% workload increase every 3 min). Gastrointestinal temperature (Tgi), heart rate, exercise performance and thermal perception were measured. Results Time to exhaustion was 16 ± 8 min shorter in the Tokyo versus the control condition (− 26 ± 11%, whereas peak power output decreased with 0.5 ± 0.3 W/kg (16 ± 7%). Greater exercise-induced increases in Tgi (1.8 ± 0.6 °C vs. 1.5 ± 0.5 °C, p Tgi (38.9 ± 0.6 °C vs. 38.7 ± 0.4 °C, p Tgi (range 0.7–3.5 °C) and peak Tgi (range 37.6–40.4 °C) were found in the Tokyo condition, with greater Tgi responses in endurance versus mixed- and skill-trained athletes. Peak thermal sensation and thermal comfort scores deteriorated in the Tokyo condition, with aggravated responses for power versus endurance- and mixed-trained athletes. Conclusion Large performance losses and Tgi increases were found among elite athletes exercising in simulated Tokyo conditions, with a substantial interindividual variation and significantly different responses across sport disciplines. These findings highlight the importance of an individual approach to optimally prepare athletes for safe and maximal exercise performance during the Tokyo Olympics.

Contains fulltext : 238809.pdf (Publisher’s version ) (Open Access) The environmental conditions during the Tokyo Olympic and Paralympic Games are expected to be challenging, which increases the risk for participating athletes to develop heat-related illnesses and experience performance loss. To allow safe and optimal exercise performance of Dutch elite athletes, the Thermo Tokyo study aimed to determine thermoregulatory responses and performance loss among elite athletes during exercise in the heat, and to identify personal, sports-related, and environmental factors that contribute to the magnitude of these outcomes. For this purpose, Dutch Olympic and Paralympic athletes performed two personalized incremental exercise tests in simulated control (15°C, relative humidity (RH) 50%) and Tokyo (32°C, RH 75%) conditions, during which exercise performance and (thermo)physiological parameters were obtained. Thereafter, athletes were invited for an additional visit to conduct anthropometric, dual-energy X-ray absorptiometry (DXA), and 3D scan measurements. Collected data also served as input for a thermophysiological computer simulation model to estimate the impact of a wider range of environmental conditions on thermoregulatory responses. Findings of this study can be used to inform elite athletes and their coaches on how heat impacts their individual (thermo)physiological responses and, based on these data, advise which personalized countermeasures (i.e. heat acclimation, cooling interventions, rehydration plan) can be taken to allow safe and maximal performance in the challenging environmental conditions of the Tokyo 2020 Olympic and Paralympic Games.

Variants in the ryanodine receptor-1 gene (RYR1) have been associated with a wide range of neuromuscular conditions, including various congenital myopathies and malignant hyperthermia (MH). More recently, a number of RYR1 variants, mostly MH-associated, have been demonstrated to contribute to rhabdomyolysis events not directly related to anesthesia in otherwise healthy individuals. This review focuses on RYR1-related rhabdomyolysis in the context of several clinical presentations (i.e., exertional rhabdomyolysis, exertional heat illnesses and MH), and conditions involving a similar hypermetabolic state, in which RYR1 variants may be present (i.e., neuroleptic malignant syndrome and serotonin syndrome). The variety of triggers that can evoke rhabdomyolysis, on their own or in combination, as well as the number of potentially associated complications, illustrates that this is a condition relevant to several medical disciplines. External triggers include but are not limited to strenuous physical exercise, especially if unaccustomed or performed under challenging environmental conditions (e.g., high ambient temperature or humidity), alcohol/illicit drugs, prescription medication (in particular statins, other anti-lipid agents, antipsychotics and antidepressants) infection, or heat. Amongst all patients presenting with rhabdomyolysis, genetic susceptibility is present in a proportion, with RYR1 being one of the most common genetic causes. Clinical clues for a genetic susceptibility include recurrent rhabdomyolysis, creatine kinase (CK) levels above 50 times the upper limit of normal, hyperCKemia lasting for 8 weeks or longer, drug/medication doses insufficient to explain the rhabdomyolysis event, and positive family history. For the treatment or prevention of RYR1-related rhabdomyolysis, the RYR1 antagonist dantrolene can be administered, both in the acute phase or prophylactically in patients with a history of muscle cramps and/or recurrent rhabdomyolysis events. Aside from dantrolene, several other drugs are being investigated for their potential therapeutic use in RYR1-related disorders. These findings offer further therapeutic perspectives for humans, suggesting an important area for future research.

Contains fulltext : 252160.pdf (Publisher’s version ) (Open Access)

Background: Adequate animal-based protein intake can attenuate exercise induced-muscle damage (EIMD) in young adults. We examined the effects of 13 days plant-based (pea) protein supplementation compared to whey protein and placebo on EIMD in active older adults. Methods: 47 Physically active older adults (60+ years) were randomly allocated to the following groups: (I) whey protein (25 g/day), (II) pea protein (25 g/day) or (III) iso-caloric placebo. Blood concentrations of creatine kinase (CK) and lactate dehydrogenase (LDH), and skeletal muscle mass, muscle strength and muscle soreness were measured prior to and 24 h, 48 h and 72 h after a long-distance walking bout (20–30 km). Results: Participants walked 20–30 km and 2 dropped out, leaving n = 15 per subgroup. The whey group showed a significant attenuation of the increase in EIMD at 24 h post-exercise compared to the pea and placebo group (CK concentration: 175 ± 90 versus 300 ± 309 versus 330 ± 165, p = p < 0.001). No differences in LDH levels, muscle strength, skeletal muscle mass and muscle soreness were observed across groups (all p-values > 0.05). Conclusions: Thirteen days of pea protein supplementation (25 g/day) does not attenuate EIMD in older adults following a single bout of prolonged walking exercise, whereas the whey protein supplementation group showed significantly lower post-exercise CK concentrations.

The combination of an exacerbated workload and impermeable nature of the personal protective equipment (PPE) worn by COVID-19 healthcare workers increases heat strain. We aimed to compare the prevalence of heat strain symptoms before (routine care without PPE) versus during the COVID-19 pandemic (COVID-19 care with PPE), identify risk factors associated with experiencing heat strain, and evaluate the access to and use of heat mitigation strategies. Dutch healthcare workers (n = 791) working at COVID-19 wards for ≥1 week, completed an online questionnaire to assess personal characteristics, heat strain symptoms before and during the COVID-19 pandemic, and the access to and use of heat mitigation strategies. Healthcare workers experienced ~25× more often heat strain symptoms during medical duties with PPE (93% of healthcare workers) compared to without PPE (30% of healthcare workers; OR = 25.57 (95% CI = 18.17–35.98)). Female healthcare workers and those with an age

The environmental conditions during the Tokyo Olympic and Paralympic Games are expected to be challenging, which increases the risk for participating athletes to develop heat-related illnesses and experience performance loss. To allow safe and optimal exercise performance of Dutch elite athletes, the Thermo Tokyo study aimed to determine thermoregulatory responses and performance loss among elite athletes during exercise in the heat, and to identify personal, sports-related, and environmental factors that contribute to the magnitude of these outcomes. For this purpose, Dutch Olympic and Paralympic athletes performed two personalized incremental exercise tests in simulated control (15°C, relative humidity (RH) 50%) and Tokyo (32°C, RH 75%) conditions, during which exercise performance and (thermo)physiological parameters were obtained. Thereafter, athletes were invited for an additional visit to conduct anthropometric, dual-energy X-ray absorptiometry (DXA), and 3D scan measurements. Collected data also served as input for a thermophysiological computer simulation model to estimate the impact of a wider range of environmental conditions on thermoregulatory responses. Findings of this study can be used to inform elite athletes and their coaches on how heat impacts their individual (thermo)physiological responses and, based on these data, advise which personalized countermeasures (i.e. heat acclimation, cooling interventions, rehydration plan) can be taken to allow safe and maximal performance in the challenging environmental conditions of the Tokyo 2020 Olympic and Paralympic Games.

Contains fulltext : 238795.pdf (Publisher’s version ) (Closed access) BACKGROUND: Emerging evidence suggests that increasing dietary nitrate intake may be an effective approach to improve cardiovascular health. However, the effects of a prolonged elevation of nitrate intake through an increase in vegetable consumption are understudied. OBJECTIVE: Our primary aim was to determine the impact of 12 wk of increased daily consumption of nitrate-rich vegetables or nitrate supplementation on blood pressure (BP) in (pre)hypertensive middle-aged and older adults. METHODS: In a 12-wk randomized, controlled study (Nijmegen, The Netherlands), 77 (pre)hypertensive participants (BP: 144 ± 13/87 ± 7 mmHg, age: 65 ± 10 y) either received an intervention with personalized monitoring and feedback aiming to consume ∼250-300 g nitrate-rich vegetables/d (∼350-400 mg nitrate/d; n = 25), beetroot juice supplementation (400 mg nitrate/d; n = 26), or no intervention (control; n = 26). Before and after intervention, 24-h ambulatory BP was measured. Data were analyzed using repeated measures ANOVA (time × treatment), followed by within-group (paired t-test) and between-group analyses (1-factor ANOVA) where appropriate. RESULTS: The 24-h systolic BP (SBP) (primary outcome) changed significantly (P-interaction time × treatment = 0.017) with an increase in the control group (131 ± 8 compared with 135 ± 10 mmHg; P = 0.036); a strong tendency for a decline in the nitrate-rich vegetable group (129 ± 10 compared with 126 ± 9 mmHg; P = 0.051) which was different from control (P = 0.020); but no change in the beetroot juice group (133 ± 11 compared with 132 ± 12 mmHg; P = 0.56). A significant time × treatment interaction was also found for daytime SBP (secondary outcome, P = 0.011), with a significant decline in the nitrate-rich vegetable group (134 ± 10 compared with 129 ± 9 mmHg; P = 0.006) which was different from control (P = 0.010); but no changes in the beetroot juice (138 ± 12 compared with 137 ± 14 mmHg; P = 0.41) and control group (136 ± 10 compared with 137 ± 11 mmHg; P = 0.08). Diastolic BP (secondary outcome) did not change in any of the groups. CONCLUSIONS: A prolonged dietary intervention focusing on high-nitrate vegetable intake is an effective strategy to lower SBP in (pre)hypertensive middle-aged and older adults. This trial was registered at www.trialregister.nl as NL7814.

Thermal perception, including thermal sensation (TS), influences exercise performance in the heat. TS is a widely used measure and we examined the impact of initial TS (iTS) on performance loss during exercise in simulated Tokyo environmental conditions among elite athletes.105 Elite outdoor athletes (endurance, skill, power and mixed trained) participated in this crossover study. Participants performed a standardized exercise test in control (15.8 ± 1.2 °C, 55 ± 6% relative humidity (RH)) and simulated Tokyo (31.6 ± 1.0 °C, 74 ± 5% RH) conditions to determine performance loss. TS was assessed ± 5 min prior to exercise (iTS) and every 5 min during the incremental exercise test (TS). Based on iTS in the Tokyo condition, participants were allocated to a neutral (iTS = 0, n = 11), slightly warm (iTS = 1, n = 50), or warm-to-hot (iTS = 2/3, n = 44) subgroup.For the whole cohort iTS was 1 [1-2] and TS increased to 3 [3-3] at the end of exercise in the Tokyo condition. Average performance loss was 26.0 ± 10.7% in the Tokyo versus control condition. The slightly warm subgroup had less performance loss (22.3 ± 11.3%) compared to the warm-to-hot subgroup (29.4 ± 8.5%, p = 0.003), whereas the neutral subgroup did not respond different (28.8 ± 11.0%, p = 0.18) from the slightly warm subgroup.iTS impacted the magnitude of performance loss among elite athletes exercising in hot and humid conditions. Athletes with a warm-to-hot iTS had more performance loss compared to counterparts with a slightly warm iTS, indicating that pre-cooling strategies and/or heat acclimation may be of additional importance for athletes in the warm-to-hot iTS group to mitigate the impact of heat stress.

Global Models are widely used to study reaction kinetics in low-temperature plasma discharges. The governing conservative equations are simplified into a system of ordinary differential equations in order to provide computationally feasible conditions to study complex chemistries with hundreds of species and thousands of reactions. This paper presents a detailed two-temperature global model for a H2O–He mixture. The model developed in this work uses a statistical thermodynamics approach to solve the heavy particles energy equation self-consistently together with the electron energy and particles balance equations in order to improve the description of reactive plasma environments. Three analytical test cases are presented to validate and demonstrate the capability of this newly developed functionality embedded in PLASIMO software's [1] global model module. The developed H2O–He models are compared with the reported results for a radio-frequency plasma [2] and then with experimental measured electron densities and gas temperature for a microwave induced plasma. In addition, conversion and energy efficiencies of hydrogen and hydrogen peroxide productions are compared with experimental values (only for hydrogen) for a pure H2O microwave induced plasma and with available literature results. This comparison underlines the challenges toward finding an optimal plasma configuration and conditions for production of hydrogen from water. The three analytical test cases for validation of the gas-temperature balance implementation in the PLASIMO global model and the detailed developed H2O–He model can be used as benchmarks for other global plasma models. The PLASIMO input files for the presented H2O–He model are available as supplementary materials (https://stacks.iop.org/PSST/30/075007/mmedia); for any future update, please consult the PLASIMO website, https://plasimo.phys.tue.nl.

The amplitude of the innate immune response reflects the degree of physiological stress imposed by exercise load. An optimal balance of exercise intensity and duration is essential for a balanced immune system and reduces the risk of dysfunction of the immune system. Therefore, it is hypothesized that neutrophils, as key players in the innate immune system, can be used as biomarker in detecting overtraining. The aim was to monitor the state of the innate immune system by phenotyping neutrophils during consecutive bouts of prolonged exercise. Study subjects were recruited from a cohort of walkers participating in a walking event on 3 consecutive days. Participants with immune deficiencies were excluded. Questionnaires to determine the physiological status of the participants were completed. Analysis of neutrophil receptor expression was done by a point‐of‐care fully automated flow cytometer. A total of 45 participants were recruited, of whom 39 participants were included for data analysis. Study participants had a median age of 64 (58‐70) years. The absolute numbers CD16dim/CD62Lbright and CD16bright/CD62Ldim neutrophils were increased after the first 2 days of exercise followed by an adaptation/normalization after the third day. Participants with activated neutrophils (high CD11b expression) had an impaired physical feeling indicated by the participant on a lower visual analog scale compared to participants who did not have activated neutrophils (P = 0.017, P = 0.022). Consecutive days of prolonged exercise results in an initial systemic innate immune response, followed by normalization/adaptation. Increased neutrophil activation was associated with impaired physical feeling measured by a validated VAS score indicated by the participant. Fully automated point‐of‐care flow cytometry analysis of neutrophil phenotypes in a field laboratory might be a useful tool to monitor relevant differences in the systemic innate immune response in response to exercise., Graphical Abstract Fully automated flow cytometry analysis of neutrophils obtained in a field laboratory after repetitive prolonged exercise.

“Faster, higher, stronger” is the official Olympic motto and illustrates that participating athletes are expected to deliver extraordinary performances to entertain spectators and achieve the highe...

Contains fulltext : 229904.pdf (Publisher’s version ) (Open Access) BACKGROUND AND OBJECTIVES: The role of exercise in the management of inflammatory bowel disease (IBD) is inconclusive as most research focused on short or low-intensity exercise bouts and subjective outcomes. We assessed the effects of repeated prolonged moderate-intensity exercise on objective inflammatory markers in IBD patients. METHODS: In this study, IBD patients (IBD walkers, n = 18), and a control group (non-IBD walkers, n = 19), completed a 30, 40 or 50 km walking exercise on four consecutive days. Blood samples were taken at baseline and every day post-exercise to test for the effect of disease on exercise-induced changes in cytokine concentrations. A second control group of IBD patients who did not take part in the exercise, IBD non-walkers (n = 19), was used to test for the effect of exercise on faecal calprotectin. Both IBD groups also completed a clinical disease activity questionnaire. RESULTS: Changes in cytokine concentrations were similar for IBD walkers and non-IBD walkers (IL-6 p = .95; IL-8 p = .07; IL-10 p = .40; IL-1β p = .28; TNF-α p = .45), with a temporary significant increase in IL-6 (p

Exertional heat stroke (EHS) is a medical emergency characterized by life-threatening hyperthermia and central nerve system dysfunction during or directly after exercise. Early recognition and aggressive cooling reduces morbidity and mortality of patients with EHS. Therefore, all health care professionals involved in acute care should immediately recognise EHS and start cooling with cold water immersion as soon as possible. Most EHS occur in young and healthy individuals without a medical history, such as athletes or soldiers. We report the case of EHS in a 26-year-old man without a medical history. He suffered from EHS during a military admission test. A few years later he had a second EHS during military training. This time, the EHS was complicated by compartment syndrome, rhabdomyolysis, acute kidney injury and epilepsy. He fully recovered from both EHS episodes. Muscle histology, whole exome sequencing and heat tolerance tests did not show any abnormalities.

BACKGROUND Neutrophils and monocytes are key immune effector cells in inflammatory bowel disease (IBD) that is associated with chronic inflammation in the gut. Patients with stable IBD who perform exercise have significantly fewer flare-ups of the disease, but no underlying mechanism has been identified. Therefore, the aim of this study was to compare the responsiveness/refractoriness of these innate immune cells after repeated bouts of prolonged exercise in IBD patients and controls. METHODS Patients with IBD and age- and gender-matched healthy controls were recruited from a cohort of walkers participating in a 4-day walking event. Blood analysis was performed at baseline and after 3 days of walking. Responsiveness to the bacterial/mitochondrial-stimulus N-Formylmethionine-leucyl-phenylalanine (fMLF) was tested in granulocytes and monocytes by measuring the expression of activation markers after adding this stimulus to whole blood. RESULTS In total 38 participants (54 ± 12 years) were included in this study: 19 walkers with and 19 walkers without IBD. After 3 days of prolonged exercise, a significant increase in responsiveness to fMLF was observed in all participants irrespective of disease. However, IBD patients showed significantly less responsiveness in neutrophils and monocytes, compared with non-IBD walkers. CONCLUSIONS Increased responsiveness of neutrophils and monocyte to fMLF was demonstrated after repetitive bouts of prolonged exercise. Interestingly, this exercise was associated with relative refractoriness of both neutrophils and monocytes in IBD patients. These refractory cells might create a lower inflammatory state in the intestine providing a putative mechanism for the decrease in flare-ups in IBD patients after repeated exercise.

Background: It is unknown whether protein supplementation can enhance recovery of exercise-induced muscle damage in older adults who have a disturbed muscle protein synthetic response. We assessed whether protein supplementation could attenuate exercise-induced muscle damage and soreness after prolonged moderate-intensity walking exercise in older adults. Methods: In a double-blind, placebo-controlled intervention study, 104 subjects (81% male, &ge, 65 years) used either a protein (n = 50) or placebo supplement (n = 54) during breakfast and directly after exercise. Within a walking event, study subjects walked 30/40/50 km per day on three consecutive days. Muscle soreness and fatigue were determined with a numeric rating scale, and creatine kinase (CK) concentrations and serum inflammation markers were obtained. Results: Habitual protein intake was comparable between the protein (0.92 &plusmn, 0.27 g/kg/d) and placebo group (0.97 &plusmn, 0.23 g/kg/d, p = 0.31). At baseline, comparable CK concentrations were found between the protein and the placebo group (110 (IQR: 84&ndash, 160 U/L) and 115 (IQR: 91&ndash, 186 U/L), respectively, p = 0.84). Prolonged walking (protein: 32 &plusmn, 9 km/d, placebo: 33 &plusmn, 6 km/d) resulted in a cumulative increase of CK in both the protein (∆283 (IQR: 182&ndash, 662 U/L)) and placebo group (∆456 (IQR: 209&ndash, 885 U/L)) after three days. CK elevations were not significantly different between groups (p = 0.43). Similarly, no differences in inflammation markers, muscle soreness and fatigue were found between groups. Conclusions: Protein supplementation does not attenuate exercise-induced muscle damage, muscle soreness or fatigue in older adults performing prolonged moderate-intensity walking exercise.

Although heat exposure is the leading cause of mortality for undocumented immigrants attempting to traverse the Mexico-U.S. border, there has been little work in quantifying risk. Therefore, our study aims to develop a methodology projecting increase in core temperature over time and space for migrants in Southern Arizona using spatial analysis and remote sensing in combination with the heat balance equation—adapting physiological formulae to a multi-step geospatial model using local climate conditions, terrain, and body specifics. We sought to quantitatively compare the results by demographic categories of age and sex and qualitatively compare them to known terrestrial conditions and prior studies of those conditions. We demonstrated a more detailed measure of risk for migrants than those used most recently: energy expenditure and terrain ruggedness. Our study not only gives a better understanding of the ‘funnel effect’ mechanisms, but also provides an opportunity for relief and rescue operations.

Contains fulltext : 207107.pdf (Publisher’s version ) (Open Access) Exercising in a hot and humid environment increases core body temperature, which may limit exercise performance. The risk of exercise-induced hyperthermia and associated performance decrement in Olympic sailing athletes is largely unknown. Therefore, this study aimed to compare thermoregulatory responses and performance indicators of elite sailors in a cool versus hot and humid environment. Seven elite athletes from four different Olympic sailing classes (Laser, RS:X, Finn, 470) performed cycling and/or rowing exercise in a cool (18 degrees C) and hot (33 degrees C) environment, while core body temperature (TC), skin temperature (TSK), exercise performance (covered distance), and rating of perceived exertion were measured continuously. TC increased significantly more in the hot environment (37.6 +/- 0.2 degrees C to 39.1 +/- 0.1 degrees C) compared to the cool environment (37.5 +/- 0.1 degrees C to 38.5 +/- 0.2 degrees C; p = 0.002), but the increase in TC between conditions differed substantially within individuals (range: 0.3 degrees C - 0.9 degrees C). Exercise performance decreased by 6.2 +/- 2.9% in the hot environment (p = 0.013, range: 2.3%-9.5%), but more importantly, exercise performance was strongly inversely related to peak TC (R = -0.78, p = 0.039). Rating of perceived exertion (cool: 14.2 +/- 0.6; hot: 13.9 +/- 1.2) and increase in TSK (cool: 0.5 +/- 1.0 degrees C; hot: 0.9 +/- 0.3 degrees C) did not differ between conditions (p = 0.59 and p = 0.36, respectively). To conclude, a larger increase in TC and substantial exercise performance decrement were observed in the hot versus cool environment. As a further matter, large inter-individual differences were observed across athletes with an inverse relationship between TC and exercise performance, which stresses the importance of appropriate and personalized interventions to reduce thermoregulatory burden of elite sailors during exercise in the heat.

Item does not contain fulltext OBJECTIVES: Obesity is characterized by a pro-inflammatory state, which plays a role in the pathogenesis of metabolic and cardiovascular disease. An exercise bout causes a transient increase in pro-inflammatory cytokines, whilst training has anti-inflammatory effects. No previous study examined whether the exercise-induced increase in pro-inflammatory cytokines is altered with repeated prolonged exercise bouts and whether this response differs between lean and overweight/obese individuals. DESIGN: Lean (n=25, BMI 22.9+/-1.5kg/m(2)) and age-/sex-matched overweight/obese (n=25; BMI 27.9+/-2.4kg/m(2)) individuals performed walking exercise for 30, 40 or 50km per day on four consecutive days (distances similar between groups). METHODS: Circulating cytokines (IL-6, IL-10, TNF-alpha, IL-1beta and IL-8) were examined at baseline and

Contains fulltext : 203382.pdf (Publisher’s version ) (Open Access) BACKGROUND: An inadequate protein intake may offset the muscle protein synthetic response after physical activity, reducing the possible benefits of an active lifestyle for muscle mass. We examined the effects of 12 weeks of daily protein supplementation on lean body mass, muscle strength, and physical performance in physically active older adults with a low habitual protein intake (

Item does not contain fulltext The purpose of this study was to examine the effects of 12 weeks collagen peptide (CP) supplementation on knee pain and function in individuals with self-reported knee pain. Healthy physically active individuals (n = 167; aged 63 [interquartile range = 56-68] years) with self-reported knee pain received 10 g/day of CP or placebo for 12 weeks. Knee pain and function were measured with the Visual Analog Scale (VAS), the Lysholm questionnaire, and the Knee injury and Osteoarthritis Outcome Score (KOOS). Furthermore, we assessed changes in inflammatory, cartilage, and bone (bio)markers. Measurements were conducted at baseline and after 12 weeks of supplementation. Baseline VAS did not differ between CP and placebo (4.7 [2.5-6.1] vs. 4.7 [2.8-6.2], p = 0.50), whereas a similar decrease in VAS was observed after supplementation (-1.6 ± 2.4 vs. -1.9 ± 2.6, p = 0.42). The KOOS and Lysholm scores increased after supplementation in both groups (p values < 0.001), whereas the increase in the KOOS and Lysholm scores did not differ between groups (p = 0.28 and p = 0.76, respectively). Furthermore, CP did not impact inflammatory, cartilage, and bone (bio)markers (p values > 0.05). A reduced knee pain and improved knee function were observed following supplementation, but changes were similar between groups. This suggests that CP supplementation over a 12-week period does not reduce knee pain in healthy, active, middle-aged to elderly individuals. Novelty CP supplementation over a 12-week period does not reduce knee pain in healthy, active, middle-aged to elderly individuals. CP supplementation over a 12-week period does not impact on inflammatory, cartilage, and bone (bio)markers in healthy, active, middle-aged to elderly individuals. 01 juli 2020

Contains fulltext : 224865.pdf (Publisher’s version ) (Closed access)

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Purpose: Studies often assess the impact of sex on the relation between core body temperature (CBT), whole-body sweat rate (WBSR), and heat production during exercise in laboratory settings, but less is known in free-living conditions. Therefore, the authors compared the relation between CBT, WBSR, and heat production between sexes in a 15-km race under cool conditions. Methods: During 3 editions of the Seven Hills Run (Nijmegen, the Netherlands) with similar ambient conditions (8–12°C, 80–95% relative humidity), CBT and WBSR were measured among 375 participants (52% male) before and immediately after the 15-km race. Heat production was estimated using initial body mass and mean running speed, assuming negligible external work. Results: Men finished the race in 76 (12) minutes and women in 83 (13) minutes (P P P P = .71, ES = 0.04). Men demonstrated a greater increase in CBT (1.5°C [0.8°C] vs 1.3°C [0.7°C], respectively, P = .013, ES = 0.31); the sex difference remains after correcting for heat production (P = .004). WBSR was larger in men (18.0 [6.9] g/min) than in women (11.4 [4.7] g/min; P R2 = .395, P Conclusions: WBSR was associated with heat production, irrespective of sex, during a self-paced 15-km running race in cool environmental conditions. Men had a higher ΔCBT than women.

Contains fulltext : 174533.pdf (Publisher’s version ) (Open Access) Exercise-induced increases in core body temperature could negative impact performance and may lead to development of heat-related illnesses. The use of cooling techniques prior (pre-cooling), during (per-cooling) or directly after (post-cooling) exercise may limit the increase in core body temperature and therefore improve exercise performance. The aim of the present review is to provide a comprehensive overview of current scientific knowledge in the field of pre-cooling, per-cooling and post-cooling. Based on existing studies, we will discuss 1) the effectiveness of cooling interventions, 2) the underlying physiological mechanisms and 3) practical considerations regarding the use of different cooling techniques. Furthermore, we tried to identify the optimal cooling technique and compared whether cooling-induced performance benefits are different between cool, moderate and hot ambient conditions. This article provides researchers, physicians, athletes and coaches with important information regarding the implementation of cooling techniques to maintain exercise performance and to successfully compete in thermally stressful conditions.

This chapter describes the fundamental factors that influence heat exchange between the human body and its surrounding environment. The bulk of heat exchange takes place at the skin surface via sensible heat transfer (i.e. convection and radiation) and evaporation. With increasing ambient temperature, the gradient for sensible heat transfer declines, meaning that the human body becomes increasingly dependent on the evaporation of sweat for heat dissipation. If the combination of climate (air temperature, radiant temperature, humidity and air velocity) and clothing permit a sufficient level of heat dissipation to counterbalance the rate of internal heat production, elevations in core temperature are moderated (i.e. compensable heat stress). However, if heat production exceeds the upper capacity to lose heat from the skin surface due to high ambient temperatures, humidity, low wind speeds or high evaporative resistance of clothing, a continuous increase in core temperature occurs (i.e. uncompensable heat stress).

Background: Magnesium is essential for health and performance. Sub-optimal levels have been reported for older persons. In addition, physical exercise is known to temporally decrease magnesium blood concentrations. Objective: To investigate these observations in conjunction we assessed total (tMg) and ionized magnesium (iMg) concentrations in plasma and whole blood, respectively, during 4 consecutive days of exercise in very old vital adults. Design: 68 participants (age 83.7±1.9 years) were monitored on 4 consecutive days at which they walked 30–40km (average ∼8 hours) per day at a self-determined pace. Blood samples were collected one or two days prior to the start of exercise (baseline) and every walking day immediately post-exercise. Samples were analysed for tMg and iMg levels. Results: Baseline tMg and iMg levels were 0.85±0.07 and 0.47±0.07 mmol/L, respectively. iMg decreased after the first walking day (−0.10±0.09 mmol/L, p

Contains fulltext : 196745.pdf (Publisher’s version ) (Open Access) PURPOSE: The aim of the present study was to assess the effect of prolonged and repeated exercise on iron metabolism in middle-aged adults and to compare differences between sexes. METHODS: 50 male (58.9 +/- 9.9 year) and 48 female (50.9 +/- 11.2 year) individuals were monitored on 4 consecutive days at which they walked on average 8 h and 44 min per day at a self-determined pace. Blood samples were collected 1 or 2 days prior to the start of the exercise (baseline) and every day immediately post-exercise. Samples were analysed for iron, ferritin, haemoglobin, and haptoglobin concentrations. RESULTS: Plasma iron decreased across days, while ferritin increased across days (both p < 0.001). Haptoglobin showed a decrease (p < 0.001) after the first day and increased over subsequent days (p < 0.001). Haemoglobin did not change after the first day, but increased during subsequent days (p < 0.05). At baseline, 8% of the participants had iron concentrations below minimum reference value (10 micromol/L), this increased to 43% at day 4. There was an interaction between sex and exercise days on iron (p = 0.028), ferritin (p < 0.001) and haemoglobin levels (p = 0.004), but not on haptoglobin levels. CONCLUSION: This study showed decreases in iron, increases in ferritin, a decrease followed by increases in haptoglobin and no change followed by increases in haemoglobin. This is most likely explained by (foot strike) haemolysis, inflammation, and sweat and urine losses. These processes resulted in iron levels below minimum reference value in a large number of our participants.

Objective: The discomfort caused by rectal probes and esophageal probes for the estimation of body core temperature has triggered the development of gastrointestinal (GI) capsules that are easily accepted by athletes and workers due to their non-invasive characteristics. We compare two new GI capsule devices with rectal temperature during cycle ergometer exercise and rest. Approach: Eight participants followed a protocol of (i) 30 min exercise with a power output of 130 W, (ii) 5 min rest, (iii) 10 min self-paced maximum exercise, and (iv) 15 min rest. Core temperature was measured using two GI-capsule devices (e-Celsius and myTemp) and rectal temperature. Main results: The myTemp system provided only slightly different temperatures to the rectal temperature probe during rest and exercise. However, the factory-calibrated e-Celsius system showed a systematic rectal temperature underestimation of 0.2 °C that is corrected in the 2018 versions. Both GI capsules reacted faster to temperature changes in the body compared to the rectal temperature probe during the rest period following maximum exercise. Significance: The GI-capsules react faster to temperature changes in the body compared to the rectal temperature probe, in particular during the rest period following exercise.

Previous studies have shown that exercise-induced changes in cytokine profiles depend on exercise duration and intensity. Studies are generally limited to a single day, and insight into the time course during multiple days of exercise is lacking. Therefore, this study assessed cytokine responses during multiple days of moderate intensity exercise in men and women. Fifty males (58.9 ± 9.9 years) and fifty females (50.9 ± 11.2 years) were monitored on 4 consecutive days at which they walked on average ~9 h/d at a self-determined pace. Blood samples were collected 1 or 2 days prior to the start of the exercise (baseline) and every walking day immediately post-exercise. Blood samples were analyzed for IL-6, IL-8, IL-10, IL-1β, and TNF-α concentrations. All cytokine concentrations increased from baseline to post-exercise at day 1 (P < .001). Thereafter, concentrations decreased from day 1 to day 2 (P < .01), remaining rather stable during the next days. IL-1β and TNF-α were higher in men at baseline and during all days. In conclusion, exercise-induced cytokine increases attenuated on subsequent days, although daily workload remained constant. Men and women showed different baseline levels but similar exercise responses. These results suggest that individuals adapt rapidly to this type of repeated exercise.

The aim of the present case study was to use real-time observations to investigate ultramarathon runners' timing of food and fluid intake per 15 km and per hour, and total bodyweight loss due to dehydration. The study included 5 male ultramarathon runners observed during a 120 km race. The research team members followed on a bicycle and continuously observed their dietary intake using action cameras. Hourly carbohydrate intake ranged between 22.1 and 62.6 g/h, and fluid intake varied between 260 and 603 mL/h. These numbers remained relatively stable over the course of the ultra-endurance marathon. Runners consumed food and fluid on average 3-6 times per 15 km. Runners achieved a higher total carbohydrate consumption in the second half of the race (p = 0.043), but no higher fluid intake (p = 0.08). Energy gels contributed the most to the total average carbohydrate intake (40.2 ± 25.7%). Post-race weight was 3.6 ± 2.3% (range 0.3-5.7%) lower than pre-race weight, revealing a non-significant (p = 0.08) but practical relevant difference. In conclusion, runners were able to maintain a constant timing of food and fluid intake during competition but adjusted their food choices in the second half of the race. The large variation in fluid and carbohydrate intake indicate that recommendations need to be individualized to further optimize personal intakes.

Purpose: Telemetric temperature capsule systems are wireless, relatively noninvasive, and easily applicable in field conditions and have therefore great advantages for monitoring core body temperature. However, the accuracy and responsiveness of available capsule systems have not been compared previously. Therefore, the aim of this study was to examine the validity, reliability, and inertia characteristics of four ingestible temperature capsule systems (i.e., CorTemp, e-Celsius, myTemp, and VitalSense). Methods: Ten temperature capsules were examined for each system in a temperature-controlled water bath during three trials. The water bath temperature gradually increased from 33-C to 44-C in trials 1 and 2 to assess the validity and reliability, and from 36-C to 42-C in trial 3 to assess the inertia characteristics of the temperature capsules. Results: A systematic difference between capsule and water bath temperature was found for CorTemp (0.077-C T 0.040-C), e-Celsius (j0.081-C T 0.055-C), myTemp (j0.003-C T 0.006-C), and VitalSense (j0.017-C T 0.023-C; P G 0.010), with the lowest bias for the myTemp system (P G 0.001). A systematic difference was found between trial 1 and trial 2 for CorTemp (0.017-C T 0.083-C; P = 0.030) and e-Celsius (j0.007-C T 0.033-C; P = 0.019), whereas temperature values of myTemp (0.001-C T 0.008-C) and VitalSense (0.002-C T 0.014-C) did not differ (P 9 0.05). Comparable inertia characteristics were found for CorTemp (25 T 4 s), e-Celsius (21 T 13 s), and myTemp (19 T 2 s), whereas the VitalSense system responded more slowly (39 T 6 s) to changes in water bath temperature (P G 0.001). Conclusions: Although differences in temperature and inertia were observed between capsule systems, an excellent validity, test-retest reliability, and inertia was found for each system between 36-C and 44-C after removal of outliers.

OBJECTIVES: An accurate and non-invasive measurement of core body temperature (Tc) is of great importance to quantify exercise-induced increases in Tc in athletes or to assess changes in Tc in patient populations. The use of ingestible gastrointestinal telemetric temperature capsules is widely accepted as a surrogate marker for Tc, but widespread implementation is lacking due to the high costs of these disposable capsules. A new and cheaper temperature capsule system (i.e. myTemp) was recently introduced. The aim of present study is to determine the validity and test-retest reliability of the myTemp system. DESIGN: Ex-vivo experimental study. METHODS: Fifteen ingestible temperature capsules (myTemp, Nijmegen, Netherlands) were tested in a highly temperature controlled water bath, in which the water temperature gradually increased from 34°C to 44°C. The study protocol was performed twice for each temperature capsule. RESULTS: Mean difference between myTemp temperature and water bath temperature was -0.001±0.005°C (Limit of Agreement (LOA): ±0.011°C) during Trial 1 (p=0.11) and -0.001±0.006°C (LOA: ±0.012°C) during Trial 2 (p=0.039). Furthermore, an Intraclass Correlation Coefficient (ICC) of 1.00 was found for both trials. A systematic difference between Trials 1 and 2 of 0.004±0.008°C (LOA: ±0.015°C) was found (p

Exercise and dehydration may be associated with a compromised kidney function and potential signs of kidney injury. However, the kidney responses to exercise of different durations and hypohydration levels are not yet known. Therefore, we aimed to compare the effects of acute versus prolonged exercise and dehydration on estimated glomerular filtration rate (eGFR) and kidney injury biomarkers in healthy male adults. A total of 35 subjects (23 ± 3 years) were included and invited for two study visits. Visit 1 consisted of a maximal cycling test. On Visit 2, subjects performed a submaximal exercise test at 80% of maximal heart rate until 3% hypohydration. Blood and urine samples were taken at baseline, after 30 min of exercise (acute effects; low level of hypohydration) and after 150 min of exercise or when 3% hypohydration was achieved (prolonged effects, high level of hypohydration). Urinary outcome parameters were corrected for urinary cystatin C, creatinine, and osmolality. Subjects dehydrated on average 0.6 ± 0.3% and 2.9 ± 0.7% after acute and prolonged exercise, respectively (P 0.05), and elevated osmolality corrected uNGAL concentrations after acute and prolonged exercise (all P-values

Item does not contain fulltext Exercise-induced increase in core body temperature may lead to the development of hyperthermia (>40.0 degrees C) and/or decreased performance levels. This study examined the effects of wearing a cooling vest during a 5-km time trial on thermoregulatory responses and performance. 10 male masters athletes (42+/-10 years) performed a 5-km time trial on a motorized treadmill in a climate chamber (25 degrees C, 55% relative humidity) with and without a cooling vest. Split times, heart rate, core-, skin- and cooling vest temperature were measured every 500 m. Subjects also rated thermal comfort and level of perceived exertion. The cooling vest significantly decreased heart rate (p

Our knowledge on the molecular mechanisms of red blood cell aging is mostly derived from in vitro studies. The Four Days Marches of Nijmegen in the Netherlands, the world&rsquo, s largest yearly walking event, constitutes a unique possibility to study the effect of mechanical and biochemical stressors occurring during moderate-intensity exercise on red blood cell aging in vivo. Therefore, longitudinal measurements were performed of biophysical, immunological, and functional red blood cell characteristics that are known to change during aging. Our data show that moderate-intensity exercise induces the generation of a functionally improved red blood cell population with a higher deformability and a decreased tendency to aggregate. This is likely to be associated with an early removal of the oldest red blood cells from the circulation, as deduced from the (dis)appearance of removal signals. Thus, the physiological red blood cell aging process maintains homeostasis in times of moderate-intensity exercise-induced stress, probably by accelerated aging and subsequent removal of the oldest, most vulnerable red blood cells.

Contains fulltext : 182501.pdf (Publisher’s version ) (Open Access) Exercise may lead to kidney injury through several mechanisms. Urinary Kidney Injury Molecule-1 (uKIM1) and Neutrophil Gelatinase-Associated Lipocalin (uNGAL) are known biomarkers for acute kidney injury, but their response to repetitive exercise remains unknown. We examined the effects of a single versus repetitive bouts of exercise on markers for kidney injury in a middle-aged population. Sixty subjects (aged 29-78 years, 50% male) were included and walked 30, 40 or 50 km for three consecutive days. At baseline and after exercise day 1 and 3, a urine sample was collected to determine uNGAL and uKIM1. Furthermore, urinary cystatin C, creatinine, and osmolality were used to correct for dehydration-related changes in urinary concentration. Baseline uNGAL was 9.2 (5.2-14.7) ng/mL and increased to 20.7 (11.0-37.2) ng/mL and 14.2(8.0-26.3) ng/mL after day 1 and day 3, respectively, (P