Effects of brain and trunk temperatures on exercise performance in goats

Caputa, Michael; Feistkorn, G.; Jessen, Claus

doi:10.1007/bf00586681

Cited by 97 publications

(51 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Evidence in humans and animals also supports the notion that fatigue in hot environments appears to coincide with a critically high internal body temperature (6,11,12,14,17,24). There are reports indicating that some untrained subjects fatigued during exercise in uncompensable hot environments with body temperatures of ϳ38°C (23,26,38).…”

Section: High Temperature and Fatiguementioning

confidence: 66%

Influence of body temperature on the development of fatigue during prolonged exercise in the heat

González‐Alonso

Teller

Andersen

et al. 1999

Journal of Applied Physiology

891

741

View full text Add to dashboard Cite

Nielsen. Influence of body temperature on the development of fatigue during prolonged exercise in the heat. J. Appl. Physiol. 86(3): 1032-1039, 1999.-We investigated whether fatigue during prolonged exercise in uncompensable hot environments occurred at the same critical level of hyperthermia when the initial value and the rate of increase in body temperature are altered. To examine the effect of initial body temperature [esophageal temperature (T es ) ϭ 35.9 Ϯ 0.2, 37.4 Ϯ 0.1, or 38.2 Ϯ 0.1 (SE)°C induced by 30 min of water immersion], seven cyclists (maximal O 2 uptake ϭ 5.1 Ϯ 0.1 l/min) performed three randomly assigned bouts of cycle ergometer exercise (60% maximal O 2 uptake) in the heat (40°C) until volitional exhaustion. To determine the influence of rate of heat storage (0.10 vs. 0.05°C/min induced by a water-perfused jacket), four cyclists performed two additional exercise bouts, starting with T es of 37.0°C. Despite different initial temperatures, all subjects fatigued at an identical level of hyperthermia (T es ϭ 40.1-40.2°C, muscle temperature ϭ 40.7-40.9°C, skin temperature ϭ 37.0-37.2°C) and cardiovascular strain (heart rate ϭ 196-198 beats/min, cardiac output ϭ 19.9-20.8 l/min). Time to exhaustion was inversely related to the initial body temperature: 63 Ϯ 3, 46 Ϯ 3, and 28 Ϯ 2 min with initial T es of ϳ36, 37, and 38°C, respectively (all P Ͻ 0.05). Similarly, with different rates of heat storage, all subjects reached exhaustion at similar T es and muscle temperature (40.1-40.3 and 40.7-40.9°C, respectively), but with significantly different skin temperature (38.4 Ϯ 0.4 vs. 35.6 Ϯ 0.2°C during high vs. low rate of heat storage, respectively, P Ͻ 0.05). Time to exhaustion was significantly shorter at the high than at the lower rate of heat storage (31 Ϯ 4 vs. 56 Ϯ 11 min, respectively, P Ͻ 0.05). Increases in heart rate and reductions in stroke volume paralleled the rise in core temperature (36-40°C), with skin blood flow plateauing at T es of ϳ38°C. These results demonstrate that high internal body temperature per se causes fatigue in trained subjects during prolonged exercise in uncompensable hot environments. Furthermore, time to exhaustion in hot environments is inversely related to the initial temperature and directly related to the rate of heat storage. hyperthermia; skin blood flow; heart rate; stroke volume IT IS WELL DOCUMENTED that endurance can be impaired in hot compared with temperate climates (10,12,28) and that time to exhaustion is influenced by alterations of the initial body temperature (1,22,32,39). The attainment of a critically high level of body temperature has been proposed as the main factor limiting endurance performance in hot environments (7,28). The observation that trained subjects working at 60% of peak O 2 uptake (V O 2 peak ) in the heat [40°C, 10% relative humidity (RH)] for 9-12 consecutive days improved exercise performance from 48 to 80 min but fatigued at a core temperature of 39.7°C appears to support this notion (28). This large improvement in exercise time t...

show abstract

Section: High Temperature and Fatiguementioning

confidence: 66%

Influence of body temperature on the development of fatigue during prolonged exercise in the heat

González‐Alonso

Teller

Andersen

et al. 1999

Journal of Applied Physiology

891

741

View full text Add to dashboard Cite

show abstract

“…Selective brain cooling has been viewed as a mechanism which can protect the brain from overheating (Carithers & Seagrave, 1976) and extend the range of body core temperature over which an animal can function in hot environments and during exercise (Taylor & Lyman, 1972). However, the observation that goats can withstand brain temperatures of 42-5°C without apparent deleterious effect (Caputa, Feistkorn & Jessen, 1986) suggested that the vulnerability of the brain to thermal damage might not be as important as once believed (Burger & Fuhrman, 1964). Recently, Kuhnen & Jessen (1991) showed that SBC occurs in the normothermic range of body temperatures in goats and proposed that SBC is 'a thermoregulatory effector mechanism like shivering or panting', with thermostasis of the head rather than of the general body core as the net result.…”

Section: Introductionmentioning

confidence: 99%

Selective brain cooling in goats: effects of exercise and dehydration.

Baker

Nijland

1993

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. Measurements of brain and central blood temperature (Tbr and Tbl), metabolic rate (MR) and respiratory evaporative heat loss (REHL) were made in trained goats walking on a treadmill at 4'8 km h-' at treadmill inclines of 0, 5, 10, 15 and 20 % when they were fully hydrated and at 0 % when they had been deprived of water for 72 h.2. In hydrated goats, exercise MR increased progressively with increasing treadmill incline. Both Tbl and Tbr rose during exercise, but Tbl always rose more than Tbr, and selective brain cooling (SBC = Tbl-Tbr) increased linearly with Tbl. Significant linear relationships were also present between REHL and Tbl and between SBC and REHL. Neither the slope of the regression relating SBC to Tbl nor the threshold Tbl for onset of SBC was affected by exercise intensity. Manual occlusion of the angularis oculi veins decreased SBC in a walking goat, while occlusion of the facial veins increased SBC. 3. Dehydrated goats had higher levels of Tbl, Tbr and SBC during exercise, but the relationship between SBC and Tbl was the same in hydrated and dehydrated animals. In dehydrated animals, REHL at a given Tbl was lower and SBC was thus maintained at reduced rates of REHL.4. It is concluded that SBC is a linear function of body core temperature in exercising goats and REHL appears to be a major factor underlying SBC in exercise. The maintenance of SBC in spite of reduced REHL in dehydrated animals could be a consequence of increased vascular resistance in the facial vein and increased flow of cool nasal venous blood into the cranial cavity.

show abstract

“…Both studies showed a linear relationship between α β T c during exercise hyperthermia. Further evidence to support the idea of high brain temperature as a limiting factor during exercise comes from research demonstrating attenuated running performance in goats after elevating hypothalamic temperature (Caputa et al, 1986). Based on these findings, investigators hypothesize that inhibitory signals arise from temperature-sensitive areas in the hypothalamus and attenuate motor activity when body temperature rises (Nybo & Nielsen, 2001a;Nybo, 2012).…”

Section: Central-related Factorsmentioning

confidence: 99%

Precooling and Warm-up Effects on Time Trial Cycling Performance During Heat Stress

Al-Horani

Wingo

2015

Medicine &Amp; Science in Sports &Amp; Exercise

View full text Add to dashboard Cite

The aim of this study was to investigate the separate and combined effects of precooling and warm-up on a subsequent cycling time trial in a hot environment. Nine healthy men (mean±SD age=24±5 years; body mass=74.7±4.5 kg; height=171.4±7.7 cm; body fat=12.9±5.2%) completed 3 simulated 16.1-km time trials on a cycle ergometer in a hot environment (~33 °C, 45% relative humidity) after: 1) 20 min of fluid ingestion (10 °C ) followed by 30 min of ice-slurry ingestion (-1 °C ) coupled with ice-vest (PREC), 2) 30 min of ice-slurry ingestion coupled with ice-vest followed by 20 min of warm-up including ice-slurry and ice-vest (COMBO), 3) 30 min of fluid ingestion (10 °C) followed by 20 min of warm-up (WU). At baseline, rectal temperature (T re ), mean skin temperature ( sk ), and mean body temperature ( b ) were similar among treatments (all P>0.05). After treatment administration and before the start of the time trial, T re was lower in PREC (36.1±0.3) and COMBO (36.9±0.4) compared to WU (37.6±0.2) (all P<0.05). sk and b were all lower in PREC than COMBO and WU, and were lower in COMBO than WU (all P<0.05). T re remained lower in PREC than WU throughout exercise and was lower in PREC than COMBO for the first 12 km (all P<0.01), while T re in COMBO remained lower than WU for the first 4 km. sk during PREC was lower than COMBO at 4 and 8 km and lower than WU at 0 and 4 km, while during COMBO it was lower than WU at 0 and 4 km (all P<0.05). Heart rate (HR) at baseline was lower in PREC than COMBO and WU (68±10, 106±12, 101±13 beats/min, respectively; P<0.001). During exercise, HR increased similarly among all treatments throughout exercise (all P>0.05). Local sweat rate (SR) was lower in PREC than COMBO and WU for the first 4 km (P < iv ACKNOWLEDGMENTS All praise is due to Allah, the entirely merciful; I thank him and praise him. He is the one who protects and guards me in the days when I work, and in the nights when I sleep. He amply bestowed his favors and bounties upon me, and gave me from all I asked of him, and if I should count his favors, surely I could not enumerate.Then, I would like to express my deepest gratitude to my advisor Dr. Jonathan Wingo for his guidance, knowledge, patience, diligence, and dedication throughout this dissertation stages.He was very generous in teaching the procedures of research, from how to professionally use the laboratory equipment, to how to write a solid work of research. He has been sincere, respectful, and hardworking. I am also thankful to my dissertation committee, Dr. Philip Bishop, Dr. Mark Richardson, Dr. Edward Mansfield, and Dr. John Vincent. Their inputs, suggestions, and recommendations were very effective in directing the research into the right way. Also I thank them for their cooperation and sacrifices to finish this dissertation successfully.

show abstract

Effects of brain and trunk temperatures on exercise performance in goats

Cited by 97 publications

References 25 publications

Influence of body temperature on the development of fatigue during prolonged exercise in the heat

Influence of body temperature on the development of fatigue during prolonged exercise in the heat

Selective brain cooling in goats: effects of exercise and dehydration.

Precooling and Warm-up Effects on Time Trial Cycling Performance During Heat Stress

Contact Info

Product

Resources

About