Body temperature manipulation and exercise performance in athletically trained males

Exercise or activity in high ambient temperatures offers a particular challenge to the thermoregulatory system. It is likely that mechanisms such as sweat evaporation alone are not sufficient for maintaining body temperature within a safe limit (~36.5-38.5˚C) and below 40˚C, which may result in impaired physiological function and performance. Exogenous cooling may be of benefit prior to, during and after events that place increased thermal strain due to increased metabolic heat production and elevated environmental temperatures upon the thermoregulatory system. Conversely, in situations where it is not possible to maintain body temperature via either continued physical activity or elevated ambient temperatures, exogenous heating may be required in order to allow optimal physiological performance. Few studies have directly aligned cooling devices with data detailing effective target regions for cooling to allow a pre-cooling garment to be of minimal weight but maximal cooling efficiency. Conversely, no study has considered the effect of muscle temperature maintenance during rest periods on subsequent power-based activities. The aim of this thesis was to determine ways in which body temperature manipulation is capable of improving exercise performance in both power and endurance-based events. It was hypothesised that the manipulation of body temperature will result in subsequent changes in body temperature that would improve performance. Specifically, the use of pre-cooling would result in a reduction of body temperature and improve endurance exercise performance. Conversely, maintaining Tm following warm up completion would have a beneficial effect on sprint and power related performance. Study one set out to determine differences in regional body heat loss in 12 individual anatomical zones using a water perfused suit. Data obtained from this initial study allowed for the specific targeting of regions that were identified as having high rates of heat loss in subsequent studies that focused on pre-cooling and performance. The anatomical regions identified as having high potential affinity for heat exchange with the surrounding environment and cooling devices were the hands, forearms, upper and lower back and torso. Subsequent studies demonstrated that cooling of these areas was capable of lowering thermal sensation and improving thermal comfort prior to and during exercise in moderate environmental conditions (24˚C, 50% RH). In these moderate conditions, there was no statistically significant improvement in treadmill based self-paced 5000m running performance. However, in hot conditions (35˚C 50% RH), the use of a cooling vest and sleeves did yield a significant improvement in cycling time trial performance, which equated to 4.8%. This leads to the suggestion that there may be a threshold ambient temperature, above which pre-cooling becomes an important tool in maximizing performance potential. A parallel area of investigation, on the other side of the temperature spectrum, was the effect of muscle temperature manipulation on power-based exercise performance. The relationship between increased muscle temperature and power output is well established, however little is known about the effect of enforced rest or recovery between two bouts of exercise. Therefore, two studies were conducted to establish what affect a delay between warm up completion and exercise has on muscle temperature and subsequent sprint cycling performance. It was shown that with 30-minutes of rest between exercise bouts wearing tracksuit trousers, muscle temperature declined significantly (~1-1.5˚C). This decline was attenuated with the use of external passive electrical heating during the recovery compared to recovery completed in tracksuit trousers alone. The attenuated decline in muscle temperature following the use of the heated trousers resulted in an improvement in sprint cycling performance (~9%), with the use of insulated trousers having no effect on any variables measured, all relative to wearing tracksuit trousers in the rest period. In a follow-up study, the effect of implementing the heated trousers during the warm up and in addition to the rest period had on muscle temperature increase and sprint performance. A secondary area of investigation in this study was to determine the linearity of muscle temperature decline following warm up cessation. This study demonstrated that there was no additional benefit of combining passive heating with an active warm up on either muscle temperature elevations or subsequent sprint performance compared to the active warm up alone. It was shown that when the no heating was used at any stage, muscle temperature declined exponentially. However, when the heated trousers were used during recovery and/or during warm up, muscle temperature levelled off at a higher value towards the end of the recovery period. This study was also able to show significant improvements in absolute, relative and mean power output following the use of the heated trousers in the warm up and recovery, or the recovery alone. This thesis has identified ways in which body temperature may be manipulated in order to benefit both sprint and endurance exercise performance, using both pre-cooling and active heating. A novel concept for minimizing muscle temperature decline during periods of inactivity between different rounds of competition was shown to maximize sprint performance yielding significant improvements in peak and mean power outputs

Effect of combinations of passive and active warming on muscle temperature and sprint performance

Muscle temperature (Tm) has a significant effect on muscle function, force and power production [1], hence the adoption of warm up procedures before power based events. In the majority of sprint or power based events there are periods of maximal activity interspersed with periods of low or no activity, during which Tm may decline, adversely affecting subsequent performance. We have previously shown that Tm will decline during 30 minutes of inactivity following the completion of a warm up, and that the use of passive external heating between warm up completion and sprint cycling performance reduces Tm decline and improves peak power output [2]. The aim of the present study was to follow on from our first Tm study and determine whether, apart from using the electrical heating between warm up and event, there is an additional benefit of using the electrical heating during warm up completion on muscle temperature and subsequent measures of sprint cycling performance. The secondary goal was to look at the efficacy of a redesigned heating system covering a larger area of muscle than in [2]

Acute and chronic effects of hot water immersion on inflammation and metabolism in sedentary, overweight adults

Regular exercise-induced acute inflammatory responses are suggested to improve the inflammatory profile and insulin sensitivity. As body temperature elevations partly mediate this response, passive heating might be a viable tool to improve the inflammatory profile. This study investigated the acute, and chronic effects of hot water immersion on inflammatory and metabolic markers. Ten sedentary, overweight males (BMI: 31.0±4.2 kg/m2) were immersed in water set at 39°C for 1 h (HWI) or rested for 1 h at ambient temperature (AMB). Venous blood was obtained prior to, immediately post and 2 h post-session for assessment of monocyte intracellular heat shock protein 72 (iHsp72) and plasma concentrations of extracelullar heat shock protein 72 (eHsp72), interleukin-6 (IL-6), fasting glucose, insulin and nitrite. Thereafter, participants underwent a 2-week intervention period, consisting of 10 hot water immersion sessions (INT). Eight BMI-matched participants (BMI: 30.0±2.5 kg/m2) were included as control (CON). Plasma IL-6 and nitrite concentrations were higher immediately following HWI compared to AMB (IL-6 p<0.001, HWI: 1.37±0.94 to 2.51±1.49 pg/ml; nitrite p=0.04, HWI: 271±52 to 391±72 nM), while iHsp72 expression was unchanged (p=0.57). In contrast to resting iHsp72 expression (p=0.59), fasting glucose (p=0.04, INT: 4.44±0.93 to 3.98±0.98 mmol/l), insulin (p=0.04, INT: 68.1±44.6 to 55.0±29.9 pmol/l) and eHsp72 (p=0.03, INT: 17±41% reduction) concentrations were lowered after INT compared to CON. HWI induced an acute inflammatory response and increased nitric oxide bioavailability. The reductions in fasting glucose and insulin concentrations following the chronic intervention suggest that hot water immersion may serve as a tool to improve glucose metabolism

TRANSFORMATION OF TYPO-MORPHOLOGY OF COLUMBIA CIRCLE IN SHANGHAI CHANGING DISTRICT

Proceedings of the XXV ISUF International Conference “Urban Form and Social Context: from Traditions to Newest Demands” (Krasnoyarsk, July 5–9, 2018)This paper studies transformation of the typo-morphology of Columbia Circle in Shanghai Changning District from 1931 to 2018. Columbia Circle was initiated as a real estate project and became a valuable historic area with master pieces. The typo-morphology of Columbia Circle has gone through a significant transformation process from a suburb to the inner city during different periods of time. Through a diachronic study, the typo-morphology of Columbia Circle in different periods can be presented in several diagrams, which locate the specific variants of morphology in each period. Based on typological reading, the authors aim to explore the rules of its transformation process which reveal social and cultural forces behind. Some questions are raised in this research, i.e. what is the typo-morphology transformation process of Columbia Circle? How to define different phases according to the typo-morphological features? How is the current typo-morphology changing? How does the physical transformation reflect on the changing of social conditions of Columbia Circle? After a preliminary study, the authors conclude five transformation periods: main construction period, second phase construction, plan lot subdivision, property subdivision and property reunification. Specific character of urban morphology and building types reflect the changing of social conditions in concession, from construction to localization and eventually to gentrification. The research of Columbia Circle presents the influence of social forces on typo-morphology, which enlightens the policy making for urban regeneration and heritage preservation in Shanghai's historical districts

Assessing the lower temperature limit for comfort in footwear

When selecting clothing and equipment for use in the cold, consumers often receive only limited guidance from product information provided by manufacturers. In the area of sleeping bags the introduction of standards for their climatic range assessment, though often heavily debated by manufacturers, has undoubtedly provided consumers with guidance. Currently no such standards exist for outdoor footwear. Many manufacturers of footwear do claim certain lower temperature limits, going to -40ºC in some cases. No information is however provided on how this is tested and what criteria are applied. Kuklane et al. (1999) did several studies on the relation between footwear insulation and comfort range, but so far this has to our knowledge not led to the development of a standard. In the present study, following up on work by Kuklane, an attempt was made to collect physiological data that may be used in setting criteria for the lower temperature range of footwear