Exercise and Heat Stress: Inflammation and the Iron Regulatory Response

2021 ◽  
pp. 1-6
Author(s):  
Alannah K.A. McKay ◽  
Rachel McCormick ◽  
Nicolin Tee ◽  
Peter Peeling
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Venous Blood ◽  
Treadmill Running ◽  
Maximum Heart Rate ◽  
Physiological Strain ◽  
Running Speed ◽  
Hot Environments ◽  
The Impact ◽  
Cool Conditions

This study determined the impact of heat stress on postexercise inflammation and hepcidin levels. Twelve moderately trained males completed three, 60-min treadmill running sessions under different conditions: (a) COOL, 18 °C with speed maintained at 80% maximum heart rate; (b) HOTHR, 35 °C with speed maintained at 80% maximum heart rate; and (c) HOTPACE, 35 °C completed at the average running speed from the COOL trial. Venous blood samples were collected pre-, post-, and 3-hr postexercise and analyzed for serum ferritin, interleukin-6 (IL-6), and hepcidin concentrations. Average HR was highest during HOTPACE compared with HOTHR and COOL (p < .001). Running speed was slowest in HOTHR compared with COOL and HOTPACE (p < .001). The postexercise increase in IL-6 was greatest during HOTPACE (295%; p = .003). No differences in the IL-6 response immediately postexercise between COOL (115%) and HOTHR (116%) were evident (p = .992). No differences in hepcidin concentrations between the three trials were evident at 3 hr postexercise (p = .407). Findings from this study suggest the IL-6 response to exercise is greatest in hot compared with cool conditions when the absolute running speed was matched. No differences in IL-6 between hot and cool conditions were evident when HR was matched, suggesting the increased physiological strain induced from training at higher intensities in hot environments, rather than the heat per se, is likely responsible for this elevated response. Environmental temperature had no impact on hepcidin levels, indicating that exercising in hot conditions is unlikely to further impact transient alterations in iron regulation, beyond that expected in temperate conditions.

Stability of Heart Rate at Physiological Thresholds Between Temperate and Heat Stress Environments in Endurance-Trained Males

2020 ◽  
pp. 1-4
Author(s):  
Ed Maunder ◽  
Daniel J. Plews ◽  
Fabrice Merien ◽  
Andrew E. Kilding
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Relative Humidity ◽  
Blood Lactate ◽  
Endurance Athletes ◽  
Heart Rates ◽  
Stress Environments ◽  
Positive Correlations ◽  
Hot Environments ◽  
Stress Training

Many endurance athletes perform specific blocks of training in hot environments in “heat stress training camps.” It is not known if physiological threshold heart rates measured in temperate conditions are reflective of those under moderate environmental heat stress. A total of 16 endurance-trained cyclists and triathletes performed incremental exercise assessments in 18°C and 35°C (both 60% relative humidity) to determine heart rates at absolute blood lactate and ventilatory thresholds. Heart rate at fixed blood lactate concentrations of 2, 3, and 4 mmol·L−1 and ventilatory thresholds were not significantly different between environments (P > .05), despite significant heat stress-induced reductions in power output of approximately 10% to 17% (P < .05, effect size = 0.65–1.15). The coefficient of variation for heart rate at these blood lactate concentrations (1.4%−2.9%) and ventilatory thresholds (2.3%−2.7%) between conditions was low, with significant strong positive correlations between measurements in the 2 environments (r = .92–.95, P < .05). These data indicate heart rates measured at physiological thresholds in temperate environments are reflective of measurements taken under moderate environmental heat stress. Therefore, endurance athletes embarking on heat stress training camps can use heart rate–based thresholds ascertained in temperate environments to prescribe training under moderate environmental heat stress.

Submaximal Markers of Fatigue and Overreaching; Implications for Monitoring Athletes

2017 ◽  
Vol 38 (09) ◽  
pp. 675-682 ◽  
Author(s):  
André Siegl ◽  
Elisa M. Kösel ◽  
Nicholas Tam ◽  
Susanne Koschnick ◽  
Nelleke Langerak ◽  
...  
Keyword(s):  
Heart Rate ◽  
Muscle Soreness ◽  
Perceived Exertion ◽  
Heart Rate Recovery ◽  
Treadmill Running ◽  
Ratings Of Perceived Exertion ◽  
Running Speed ◽  
Early Symptoms ◽  
Delayed Onset ◽  
Trained Runners

AbstractThe regular monitoring of athletes is important to fine-tune training and detect early symptoms of overreaching. Therefore the aim of this study was to determine if a noninvasive submaximal running test could reflect a state of overreaching. 14 trained runners completed a noninvasive Lamberts Submaximal Running Test, one week before and 2 days after finishing an ultramarathon, and delayed onset of muscle soreness and the daily analysis of life demands for athletes questionnaire were also captured. After the ultramarathon, submaximal heart rate was lower at 70% (−3 beats) and 85% of peak treadmill running speed (P<0.01). Ratings of perceived exertion were higher at 60% (2 units) and 85% (one unit) of peak treadmill running speed, while 60-second heart rate recovery was significantly faster (7 beats, P<0.001). Delayed Onset of Muscle Soreness scores and the number of symptoms of stress (Daily Analysis of Life Demands for Athletes) were also higher after the ultramarathon (P<0.01). The current study shows that the Lamberts Submaximal Running Test is able to reflect early symptoms of overreaching. Responses to acute fatigue and overreaching were characterized by counterintuitive responses, such as lower submaximal heart rates and faster heart rate recovery, while ratings of perceived exertion were higher.

scholarly journals Physiological Responses to Treadmill Running With Body Weight Support in Hypoxia Compared With Normoxia

2018 ◽  
Vol 27 (3) ◽  
pp. 224-229 ◽  
Author(s):  
Ben J. Lee ◽  
Charles Douglas Thake
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Metabolic Response ◽  
Treadmill Running ◽  
Positive Pressure ◽  
Lower Body ◽  
Physiological Strain ◽  
Sports Clubs ◽  
Lower Body Positive Pressure ◽  
Body Positive

Context: Anecdotal reports suggest elite sports clubs combine lower-body positive-pressure rehabilitation with a hypoxic stimulus to maintain or increase physiological and metabolic strain, which are reduced during lower-body positive pressure. However, the effects of hypoxia on cardiovascular and metabolic response during lower-body positive-pressure rehabilitation are unknown. Objective: Evaluate the use of normobaric hypoxia as a means to increase physiological strain during body-weight-supported (BWS) running. Design: Crossover study. Setting: Controlled laboratory. Participants: Seven familiarized males (mean (SD): age, 20 (1) y; height, 1.77 (0.05) m; mass, 69.4 (5.1) kg; hemoglobin, 15.2 (0.8) g·dL−1) completed a normoxic and hypoxic (fraction of inspired oxygen [O2] = 0.14) trial, during which they ran at 8 km·h−1 on an AlterG™ treadmill with 0%, 30%, and 60% BWS in a randomized order for 10 minutes interspersed with 5 minutes of recovery. Main Outcome Measures: Arterial O2 saturation, heart rate, O2 delivery, and measurements of metabolic strain via indirect calorimetry. Results: Hypoxic exercise reduced hemoglobin O2 saturation and elevated heart rate at each level of BWS compared with normoxia. However, the reduction in hemoglobin O2 saturation was attenuated at 60% BWS compared with 0% and 30%, and consequently, O2 delivery was better maintained at 60% BWS. Conclusion: Hypoxia is a practically useful means of increasing physiological strain during BWS rehabilitation. In light of the maintenance of hemoglobin O2 saturation and O2 delivery at increasing levels of BWS, fixed hemoglobin saturations rather than a fixed altitude are recommended to maintain an aerobic stimulus.

Spectral Analysis of Impact Shock during Running

1992 ◽  
Vol 8 (4) ◽  
pp. 288-304 ◽  
Author(s):  
Martyn R. Shorten ◽  
Darcy S. Winslow
Keyword(s):  
Shock Wave ◽  
Wave Attenuation ◽  
Spectral Characteristics ◽  
Reaction Force ◽  
The Body ◽  
Treadmill Running ◽  
Running Speed ◽  
The Impact ◽  
Impact Shock Wave ◽  
Impact Shock

The purpose of this study was to determine the effects of increasing impact shock levels on the spectral characteristics of impact shock and impact shock wave attenuation in the body during treadmill running. Twelve male subjects ran at 2.0, 3.0, 4.0, and 5.0 m s−1on a treadmill. Axial accelerations of the shank and head were measured using low-mass accelerometers. The typical shank acceleration power spectrum contained two major components which corresponded to the active (5–8 Hz) and impact (12–20 Hz) phases of the time-domain ground reaction force. Both the amplitude and frequency of leg shock transients increased with increasing running speed. Greatest attenuation of the shock transmitted to the head occurred in the 15–50 Hz range. Attenuation increased with increasing running speed. Thus transmission of the impact shock wave to the head was limited, despite large increases in impact shock at the lower extremity.

scholarly journals The Impact of Wrist Percooling on Physiological and Perceptual Responses during a Running Time Trial Performance in the Heat

2020 ◽  
Vol 17 (20) ◽  
pp. 7559
Author(s):  
Kelsey Denby ◽  
Ronald Caruso ◽  
Emily Schlicht ◽  
Stephen J. Ives
Keyword(s):  
Heart Rate ◽  
Perceived Exertion ◽  
Thermal Sensation ◽  
Maximal Oxygen Consumption ◽  
Time Trial ◽  
Rating Of Perceived Exertion ◽  
Running Speed ◽  
Running Time ◽  
The Impact ◽  
Trial Performance

Environmental heat stress poses significant physiological challenge and impairs exercise performance. We investigated the impact of wrist percooling on running performance and physiological and perceptual responses in the heat. In a counterbalanced design, 13 trained males (33 ± 9 years, 15 ± 7% body fat, and maximal oxygen consumption, VO2max 59 ± 5 mL/kg/min) completed three 10 km running time trials (27 °C, 60% relative humidity) while wearing two cooling bands: (1) both bands were off (off/off), (2) one band on (off/on), (3) both bands on (on/on). Heart rate (HR), HR variability (HRV), mean arterial pressure (MAP), core temperature (TCO), thermal sensation (TS), and fatigue (VAS) were recorded at baseline and recovery, while running speed (RS) and rating of perceived exertion (RPE) were collected during the 10 km. Wrist cooling had no effect (p > 0.05) at rest, except modestly increased HR (3–5 ∆beats/min, p < 0.05). Wrist percooling increased (p < 0.05) RS (0.25 ∆mi/h) and HR (5 ∆beats/min), but not TCO (∆ 0.3 °C), RPE, or TS. Given incomplete trials, the distance achieved at 16 min was not different between conditions (off/off 1.96 ± 0.16 vs. off/on 1.98 ± 0.19 vs. on/on 1.99 ± 0.24 miles, p = 0.490). During recovery HRV, MAP, or fatigue were unaffected (p > 0.05). We demonstrate that wrist percooling elicited a faster running speed, though this coincides with increased HR; although, interestingly, sensations of effort and thermal comfort were unaffected, despite the faster speed and higher HR.

Characteristics Associated with 10-km Running Performance among a Group of Highly Trained Male Endurance Runners Age 21–63 Years

2003 ◽  
Vol 11 (3) ◽  
pp. 333-350 ◽  
Author(s):  
Stephen R. Bird ◽  
Simon C. Theakston ◽  
Andrew Owen ◽  
Alan M. Nevill
Keyword(s):  
Lactate Threshold ◽  
Rate Of Change ◽  
Treadmill Running ◽  
Free Wall ◽  
Maximum Heart Rate ◽  
Running Speed ◽  
Running Performance ◽  
Factors Associated ◽  
Endurance Runners ◽  
Single Predictor

This study assessed physiological and cardiac factors associated with 10-km running performance in a group of highly trained endurance runners age 21–63 years. Participants (N= 37) underwent a resting echocardiograph and incremental treadmill running test. They also provided information on their recent 10-km races. Data were analyzed using “best subsets” multiple regression. Declines with age were found for 10-km running speed (0.26 m · s−1· decade−1), maximum heart rate (4 beats/decade), VO2peak(6 ml · kg−1· min−1· decade−1), velocity at lactate threshold (1 m · s−1· decade−1), and VO2at lactate threshold (4 ml · kg−1· min−1· decade−1). The percentage of VO2peakat which lactate threshold occurred increased with age by 1.5% per decade. The rate of change of displacement of the atrioventricular plane at the left free wall and septum both declined by 1 cm · s−1· decade−1. The best single predictor of 10-km running speed was velocity at lactate threshold.

scholarly journals Resilience of Small Ruminants to Climate Change and Increased Environmental Temperature: A Review

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 867 ◽  
Author(s):  
Aleena Joy ◽  
Frank R. Dunshea ◽  
Brian J. Leury ◽  
Iain J. Clarke ◽  
Kristy DiGiacomo ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Ambient Temperature ◽  
Environmental Conditions ◽  
Environmental Temperature ◽  
Small Ruminant ◽  
Small Ruminants ◽  
Continuous Exposure ◽  
Hot Environments ◽  
The Impact

Climate change is a major global threat to the sustainability of livestock systems. Climatic factors such as ambient temperature, relative humidity, direct and indirect solar radiation and wind speed influence feed and water availability, fodder quality and disease occurrence, with production being most efficient in optimal environmental conditions. Among these climatic variables, ambient temperature fluctuations have the most impact on livestock production and animal welfare. Continuous exposure of the animals to heat stress compromises growth, milk and meat production and reproduction. The capacity of an animal to mitigate effects of increased environmental temperature, without progressing into stress response, differs within and between species. Comparatively, small ruminants are better adapted to hot environments than large ruminants and have better ability to survive, produce and reproduce in harsh climatic regions. Nevertheless, the physiological and behavioral changes in response to hot environments affect small ruminant production. It has been found that tropical breeds are more adaptive to hot climates than high-producing temperate breeds. The growing body of knowledge on the negative impact of heat stress on small ruminant production and welfare will assist in the development of suitable strategies to mitigate heat stress. Selection of thermotolerant breeds, through identification of genetic traits for adaption to extreme environmental conditions (high temperature, feed scarcity, water scarcity), is a viable strategy to combat climate change and minimize the impact on small ruminant production and welfare. This review highlights such adaption within and among different breeds of small ruminants challenged by heat stress.

scholarly journals Performance Diagnostic in Cross-Country Skiing

2015 ◽  
Vol 16 (2) ◽  
Author(s):  
Benedikt A. Gasser ◽  
Hans H. Hoppeler
Keyword(s):  
Heart Rate ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Endurance Capacity ◽  
Maximum Heart Rate ◽  
Running Speed ◽  
Cross Country Skiing ◽  
Cross Country ◽  
The Relationship

AbstractPurpose. Recreational cross-country skiers can benefit from a performance diagnostic when planning a training program. The aim of this study was to establish a simple test protocol to measure endurance capacity and provide training recommendations. Methods. The relationship between endurance performance and cross-country skiing technique was assessed using two tests. First, a lactate threshold test whereby running speed was determined on a treadmill at 4 mmol/l blood lactate concentration. Second, participants completed a variation of the Cooper test using skating technique on flat terrain to determine the distance covered in 12 min and maximum heart rate. Results. There was a correlative (r = 0.18 respectivelly R2 = 0.43) relationship of between the distance covered in the Cooper test and treadmill running speed at 4 mmol/l blood lactate concentration. Conclusions. The two tests allow recreational athletes to rank themselves with regards to their endurance capacity within a population. The relationship between distance covered and maximum heart rate can indicate whether future training should focus on technical or physical improvement.

scholarly journals Thermotolerance and heat acclimation may share a common mechanism in humans

2011 ◽  
Vol 301 (2) ◽  
pp. R524-R533 ◽  
Author(s):  
Matthew Kuennen ◽  
Trevor Gillum ◽  
Karol Dokladny ◽  
Edward Bedrick ◽  
Suzanne Schneider ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Heat Acclimation ◽  
Body Temperatures ◽  
Physiological Strain ◽  
Barrier Permeability ◽  
Shock Response ◽  
Gastrointestinal Barrier

Thermotolerance and heat acclimation are key adaptation processes that have been hitherto viewed as separate phenomena. Here, we provide evidence that these processes may share a common basis, as both may potentially be governed by the heat shock response. We evaluated the effects of a heat shock response-inhibitor (quercetin; 2,000 mg/day) on established markers of thermotolerance [gastrointestinal barrier permeability, plasma TNF-α, IL-6, and IL-10 concentrations, and leukocyte heat shock protein 70 (HSP70) content]. Heat acclimation reduced body temperatures, heart rate, and physiological strain during exercise/heat stress) in male subjects ( n = 8) completing a 7-day heat acclimation protocol. These same subjects completed an identical protocol under placebo supplementation (placebo). Gastrointestinal barrier permeability and TNF-α were increased on the 1st day of exercise/heat stress in quercetin; no differences in these variables were reported in placebo. Exercise HSP70 responses were increased, and plasma cytokines (IL-6, IL-10) were decreased on the 7th day of heat acclimation in placebo; with concomitant reductions in exercise body temperatures, heart rate, and physiological strain. In contrast, gastrointestinal barrier permeability remained elevated, HSP70 was not increased, and IL-6, IL-10, and exercise body temperatures were not reduced on the 7th day of heat acclimation in quercetin. While exercise heart rate and physiological strain were reduced in quercetin, this occurred later in exercise than with placebo. Consistent with the concept that thermotolerance and heat acclimation are related through the heat shock response, repeated exercise/heat stress increases cytoprotective HSP70 and reduces circulating cytokines, contributing to reductions in cellular and systemic markers of heat strain. Exercising under a heat shock response-inhibitor prevents both cellular and systemic heat adaptations.

Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake

1997 ◽  
Vol 82 (6) ◽  
pp. 2028-2035 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Carl M. Maresh ◽  
Catherine V. Gabaree ◽  
Jay R. Hoffman ◽  
Stavros A. Kavouras ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Water Intake ◽  
Rectal Temperature ◽  
Stress Test ◽  
Plasma Osmolality ◽  
Interactive Effects ◽  
Stress Tests ◽  
Physiological Strain ◽  
Exercise Induced

Armstrong, Lawrence E., Carl M. Maresh, Catherine V. Gabaree, Jay R. Hoffman, Stavros A. Kavouras, Robert W. Kenefick, John W. Castellani, and Lynn E. Ahlquist. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J. Appl. Physiol. 82(6): 2028–2035, 1997.—This investigation examined the distinct and interactive effects of initial hydration state, exercise-induced dehydration, and water rehydration in a hot environment. On four occasions, 10 men performed a 90-min heat stress test (treadmill walking at 5.6 km/h, 5% grade, 33°C, 56% relative humidity). These heat stress tests differed in pretest hydration [2 euhydrated (EU) and 2 hypohydrated (HY) trials] and water intake during exercise [2 water ad libitum (W) and 2 no water (NW) trials]. HY + NW indicated greater physiological strain than all other trials ( P < 0.05–0.001) in heart rate, plasma osmolality (Posm), sweat sensitivity (g / °C ⋅ min), and rectal temperature. Unexpectedly, final HY + W and EU + W responses for rectal temperature, heart rate, and Posm were similar, despite the initial 3.9 ± 0.2% hypohydration in HY + W. We concluded that differences in pretest Posm (295 ± 7 and 287 ± 5 mosmol/kg for HY + W and EU + W, respectively) resulted in greater water consumption (1.65 and 0.31 liter for HY + W and EU + W, respectively), no voluntary dehydration (0.9% body mass increase), and attenuated thermal and circulatory strain during HY + W.

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