Ulm, Univ. Diss., 2006.

Würzburg, Univ., Diss., 2009.

Universiẗat, Diss., 2005--Würzburg.

This overview reports 31 studies, which have been performed by the author since 1989 to define the diagnostic value of thermometry and infrared imaging in rehabilitation and rheumatology. Some investigations were designed to characterise either treatment modalities, to clarify the role of temperature measurements as a method for follow-up or treatment monitoring in certain diseases. Thermal imaging has an important impact in assisting the diagnosis of many diseases. A relationship between temperature and clinical signs was established in the following disorders: epicondylitis (correlation of hot spots with pain provocated by firm pressure or resisted movement, and pressure threshold), complex regional pain syndrome (elevated temperature is paralleled by swelling and pain, temperature elevation of the hand after radius fracture after plaster removal predicts typical X-ray changes), thoracic outlet syndrome (high correlation of the region of paresthesia and low temperature readings), muscular inactivity, acute stage of Herpes zoster and Raynaud's phenomenon. Thermal imaging is of little value for the assessment of disability in patients with knee pain and of questionable value in patients with carpal tunnel syndrome or fibromyalgia. Painful tendon insertions or acupuncture points on the auricle cannot be detected by thermal imaging. Temperature signs in epicondylitis, complex regional pain syndrome and thoracic outlet can be successfully used for treatment monitoring. This might be also the case in radiotherapy of malignant breast disease. Infrared thermography, performed immediately after physical exercise can help to identify activated muscles. The value of thermal imaging for monitoring patients with lymphedema remains questionable. Temperature signs in epicondylitis, complex regional pain syndrome and thoracic outlet can be successfully used for treatment monitoring. This might be also the case in radiotherapy of malignant breast disease. Infrared thermography, performed immediately after physical exercise can help to identify activated muscles. The value of thermal imaging for monitoring patients with lymphedema remains questionable. On the other hand as a result of these studies, it became quite clear that the heat regulatory system is connected with other regulation systems of the body. Many of these influence the perfusion of vessels, which can result in temperature changes on the surface. In addition to the circulation system, pain and muscle function are the most important links to temperature regulation. Therefore any change or therapeutic modification of these systems might be seen on thermal images.

Regular physical activity is recommended in healthy pregnancies and has been shown to mitigate adverse pregnancy outcomes. Despite the benefits, many women do not adhere to the recommendations due to concerns of exercise-induced heat stress and the dangers it could pose to the developing fetus. While the majority of the concerns raised are not grounded in evidence, currently there are no studies that directly examine the isolated influence of pregnancy on metabolic heat production resulting from physical activity. Additionally, despite the prevalent use of psycho-physical tools in clinical settings, there is a scarcity of literature exploring the relationship between the physiological and perceptual measures of exercise-induced heat strain in the pregnant population. Therefore, objective one of this thesis was to quantify the heat production resulting from light to moderate physical activity (intensities recommended during pregnancy) throughout gestation. Secondly, in objective two, physiological and perceptual measures of thermal strain were compared and assessed throughout pregnancy. In evaluating the change in heat production resulting from exercise (objective one), 10 non-pregnant control (30±1 yrs; BMI=22.3±0.8 kg/m2) and 10 pregnant (32±1 yrs; pre-pregnancy BMI=22.8±0.8 kg/m2) women performed a seven stage submaximal walking test in a thermal controlled chamber (23ºC). Testing was performed during their 1st (T1, 12-16 wks), 2nd (T2, 24-28 wks) and 3rd (T3, 34-38 wks) trimester of pregnancy while metabolic heat production was measured through indirect calorimetry. To assess the changes in thermal and perceptual strain (objective two), 16 non-pregnant control (32±1 yrs; BMI=22.7±0.7 kg/m2), and 20 pregnant (32±1; pre-pregnancy BMI=23.2±0.6 kg/m2) women underwent a graded walking exercise protocol at T2 and T3. Over the course of this test, heart rate, tympanic temperature (Ttymp), skin temperature (Tskin), rate of perceived exertion (RPE, 20-point scale) and thermal sensation (9-point scale) were assessed. Findings from this thesis show that for the same given progressive exercise test, women in T1 experienced similar metabolic heat production to their non-pregnant counterparts. However, as pregnancy progressed, women exhibited on average, a 7-8% increase in heat production per trimester of pregnancy that can be accounted for by weight gain. Further, at baseline conditions, heart rate responses increased with pregnancy, while Ttymp remained unchanged and Tskin decreased. In response to exercise, the magnitude of change in heart rate, Ttymp and Tskin did not differ between gestational conditions. Finally, a strong correlation was identified between heart rate and RPE throughout pregnancy, while thermal sensation only directly correlated with Ttymp and not Tskin. Overall, the present findings suggest that while the same progressive exercise test results in greater levels of heat production as pregnancy progresses, this is not observed in physiological or perceptual measures of heat strain. Rather, findings of this thesis support the notion of improved thermoregulatory responses to account for the increase in metabolic heat production. Moreover, the present thesis provides support for the use of the RPE and thermal sensation scales as effective psycho-physical tools in the pregnant population under conditions of light to moderate exercise in normothermic conditions.

This thesis sought to evaluate whether the impairments in nitric oxide (NO)-dependent cutaneous vasodilation and sweating observed in older adults during exercise in the heat stem from age-related increases in oxidative stress and/or arginase activity. Furthermore, we assessed whether changes in the sensitivity to NO at the level of the end-organ (i.e., cutaneous vasculature and sweat gland) also contribute. A total of 20 young (age, 23 ± 3 yrs) and 28 older (age, 63 ± 7 yrs) males completed one of two intermittent exercise protocols that consisted of two 30-min bouts of semi-recumbent cycling in the heat (35˚C) at a rate of metabolic heat production of 500 (protocol I; 11 young, 19 older) or 400 (protocol II; 9 young, 9 older) W. Each exercise bout was followed by a 20-min recovery period. During each protocol, local cutaneous vascular conductance (CVC; laser-Doppler flowmetry/mean arterial pressure) and sweat rate (SR, ventilated capsule) were continuously measured at four forearm skin sites. In protocol I, each forearm skin site was continuously perfused via intradermal microdialysis with either: 1) lactated Ringer’s serving as a control (Control); 2) 10 mM NG-nitro-L-arginine methyl ester (L-NAME), a non-selective NO synthase inhibitor; 3) 10 mM ascorbate (Ascorbate), a non-selective antioxidant or 4) a combination of 10 mM ascorbate and 10 mM L-NAME (L-NAME + Ascorbate). In protocol II, the Ascorbate and L-NAME + Ascorbate skin sites were replaced with 5 mM Nω-hydroxy-nor-Arginine + 5 mM S-(2-boronoethyl)-L-cysteine to inhibit arginase activity (Nor-NOHA+BEC) and 1 µM sodium nitroprusside, a nitric oxide donor (SNP). In the young adults during protocol I, CVC was reduced relative to Control at L-NAME (both P<0.01) and L-NAME + Ascorbate (both P≤0.03) but similar to Control at Ascorbate (both P≥0.26). In the older adults, CVC was reduced from Control during both exercise bouts at L-NAME (both P≤0.02) but not Ascorbate (both P≥0.09) or L-NAME + Ascorbate (both P≥0.15). While L-NAME (both P<0.04) and L-NAME + Ascorbate (both P<0.04) attenuated SR in the younger adults during exercise (no effect of Ascorbate; both P≥0.36), no differences between Control and any treatment site were observed in the older adults (P=0.42). However, correlational analysis revealed a moderate negative correlation between between VO2peak and the change in SR from control at the Ascorbate site during both exercise bouts (-0.55≤r≤-0.54; both P=0.02) exercise. Furthermore, the change in SR from Control at L-NAME + Ascorbate was also found to be negatively correlated with VO2peak in the second (r=-0.54; P=0.02) but not first (r=-0.42; P=0.08) exercise bout. In protocol II, CVC was reduced from Control at L-NAME in the young and older adults during both (both P<0.01) and the first (P=0.05) exercise bout, respectively. Furthermore, SR was reduced from Control in the young (both P≤0.03) but not older (P=0.28) adults at the L-NAME skin site. However, no influence of Nor-NOHA+BEC or SNP was observed in either age group for both CVC (all P≥0.38) and SR (P=0.28). This thesis demonstrates that age-related increases in oxidative stress influence cutaneous vasodilation during exercise via mechanisms independent of NO. Furthermore, the current findings suggest an effect of oxidative stress on NO-independent SR in older adults but that secondary factors (i.e., aerobic fitness and/or physical activity level) may play a modulatory role. Finally, the results of this thesis demonstrate that, during exercise in the heat, neither elevated arginase activity nor changes in the sensitivity of the thermoregulatory end-organs to NO effect the CVC and SR responses in older adults.

Evidence-based Canadian physical activity guidelines established specifically for pregnant women have shown to improve maternal and fetal outcomes, including prevention of adversities such as excess gestational weight gain, preeclampsia, and gestational diabetes. Unfortunately, most pregnant women fail to meet recommended guidelines for physical activity, and in many circumstances, the prevailing motive is due to a fear of overexertion and overheating harming the fetus. These concerns stem from reports of teratogenesis related to hyperthermia in several animal studies resulting in congenital fetal malformations. Although, due to disparities in thermoregulation between humans and animals, the findings are not entirely applicable to pregnant women. During exercise, the heat produced requires a given source of heat loss (i.e., skin blood flow/sweating) to maintain thermal homeostasis and a stable core temperature, preventing a continual rise in core temperature (i.e., teratogenesis). This thesis aims to separate the influence of pregnancy and body weight on oxygen consumption, heat production, heart rate, and rating of perceived exertion at rest (Study 1) and then during exercise (Study 2). On the other side of the heat balance equation is heat loss mechanisms; currently, the limited existing literature suggests that dry and evaporative heat loss increases as pregnancy progresses. Unfortunately, these findings are also based almost exclusively on animal studies. There has not been an established understanding of physiological, perceptual/behavioural responses in heat loss in pregnant women from early to late pregnancy, and the final study in this thesis sought to map the current literature in the format of a scoping review (Study 3). The findings of this thesis provide evidence that physiological measurements of oxygen consumption, heat production and heart rate are not influenced by stage of pregnancy, the responses increases/decrease according to total body mass. Additionally, both dry and evaporative heat loss responses appear to increase from early to late pregnancy.

Aging is associated with attenuated sweat gland function, which has been suggested to occur in a peripheral-to-central manner. However, evidence supporting this hypothesis remains equivocal. We therefore revisited this hypothesis by evaluating sweat rate across the limbs and trunk in young and older men during whole-body, passive heating. A water-perfused suit was used to raise and clamp esophageal temperature at 0.6°C (low-heat strain) and 1.2°C (moderate-heat strain) above baseline in 14 young (24 [SD 5] years) and 15 older (69 [4] years) men. Sweat rate was measured at multiple sites on the trunk (chest, abdomen) and limbs (biceps, forearm, quadriceps, calf) using ventilated capsules (3.8 cm²). Sweat rates, expressed as the average of 5 min of stable sweat rate at low- and moderate-heat strain, were compared between groups (young, older) and regions (trunk, limbs) within each level of heat strain using a linear mixed-effects model with nested intercepts (sites nested within region nested within participant). At low-heat strain, the age-related reduction in sweat rate (older-young values) was greater at the trunk (0.65 mg/cm²/min [95% CI 0.44, 0.86]) compared to the limbs (0.42 mg/cm²/min [0.22, 0.62]; interaction: p=0.010). At moderate-heat strain, sweat rate was lower in the older compared to young (main effect: p=0.025), albeit that reduction did not differ between regions (interaction: p=0.888). We conclude that, contrary to previous suggestions, the agerelated decline in sweat rate was greater at the trunk compared to the limbs at lowheat strain, with no evidence of regional variation in that age-related decline at moderate-heat strain.

No description available.

Honigbienen (Apis mellifera carnica) regulieren die Temperatur ihrer Brut in einem sehr engen Temperaturfenster, da vor allem die gedeckelte Brut sehr temperaturempfindlich reagiert (Groh et al. 2004). Die Thermoregulation ist nicht – wie lange angenommen – Beiprodukt von alltäglichen Arbeiten der Bienen im Brutbereich, sondern eine aktive und Energie- und Zeitaufwändige eigene Tätigkeit. Arbeiterinnen ziehen sich mit ihren Beinen an die Brutoberfläche, drücken ihren warmen Thorax auf die Brutdeckel und verharren so für einige Minuten um mit der eigenen Körperwärme die Brut zu temperieren (Bujok et al. 2002). Wie erwartet korrelierte die Thoraxtemperatur einer Arbeiterin mit der Frequenz der abdominalen Atembewegungen, bei sehr hohen Thoraxtemperaturen (über 40°C) erreichten die Bienen Atemfrequenzen von über 8Hz. Eine weitere Methode die Brut effektiv zu wärmen übten Bienen aus, die leere Zellen im gedeckelten Brutbereich besuchen (Kleinhenz et al. 2003). Arbeiterinnen gingen dabei bevorzugt in Zellen, die von möglichst vielen gedeckelten Zellen umgeben waren. Sowohl die Dauer der Zellbesuche, als auch die mittlere Thoraxtemperatur bei Ein- und Austritt der Zelle korrelierten mit der Anzahl der benachbarten Brutzellen – je mehr Brutzellen eine leere Zelle in ihrer direkten Nachbarschaft hatte umso länger dauerte der Besuch einer Biene und umso höher ist die Ein- bzw. Austrittstemperatur der Biene. Mindestes 48 Stunden alte Bienen unterschieden sich signifikant in ihrem Wärmeverhalten von jüngeren Bienen. Tote gedeckelte Brut wurde in manchen Fällen über viele Tage (durchgehend bis 10 Tage) gewärmt, sie unterschied sich in ihrer Temperatur nicht von unbehandelter gedeckelter Brut. In weiteren Versuchen lag die Bruttemperatur von toter Brut zwar unter der eines Kontrollbereiches, die Temperatur lag aber weiterhin im optimalen Bereich von 33,5 bis 35°C (Groh et al. 2004). In diesen Versuchen wurde die tote Brut vor dem Einsetzen in den Beobachtungsstock wieder auf 35°C erwärmt. Wachskegel in gedeckelten Zellen wurden erkannt und ausgeräumt. Aktive Signale, die von der Brut ausgehen scheinen also nicht notwendig für die effektive Bruttemperaturregulierung zu sein. Untersuchungen mittels Laser-Doppler-Vibrometrie zeigten auch keine Hinweise auf eine mechanische Kommunikation zwischen den Puppen und den Arbeiterinnen. Das Brutwärmen scheint eine Aktion zu sein, die von den Bienen nur in Gemeinschaft sinnvoll durchgeführt werden kann. In einigen Fällen kam es während der Puppenphase zu unerklärlichen Abfällen in der Bruttemperatur, die nur durch einen positiven Rückkopplungseffekt seitens der Arbeiterinnen erklärt werden kann. Beim Brutwärmen spielen die Antennen der Arbeiterinnen wahrscheinlich eine wichtige Rolle. Während sich die Bienen beim aktiven Brutwärmen den Brutdeckel annähern sind die Antennenspitzen immer auf die Brutdeckel gerichtet. Fehlen den Arbeiterinnen die Antennen, dann ist die Thermoregulation eingeschränkt oder unzureichend. Die Bruttemperatur korreliert mit der Anzahl der abgetrennten Antennensegmente, je mehr Antennensegmente fehlen, desto weniger gut wird die Temperatur im Brutbereich hoch und konstant gehalten. Zusätzlich scheint es eine Lateralität in der Antennenfunktion zu geben, wurde die rechte Antenne gekürzt wärmten die Bienen die Brut signifikant schlechter, als beim Kürzen der linken Antenne. Durch das Kürzen der Antennen änderte sich auch das Verhalten der Tiere: Kontrollbienen verharrten ruhig im Brutbereich, während Bienen mit gekürzten Antennen teilweise ähnlich warm waren, aber nicht mehr das oben beschriebene aktive Brutwärmeverhalten zeigten. / Honey bees (Apis mellifera carnica) precisely regulate brood temperature in a range between 33 to 35°C, as the development of the larvae, especially the capped brood stages are very sensitive to temperature changes. The heat used for thermoregulation in the brood area is not a by-product of work, but an active time and energy consuming task called brood heating behaviour: worker bees pull their warm thoraces towards the brood caps and remain in that position for about 10 minutes to transfer their body heat to the brood caps and the brood (Bujok et al. 2002). As expected, thoracic temperatures of bees correlated with frequency of abdominal breathing movements; bees with high thoracic temperatures (above 40°C) showed abdominal movements of up to slightly over 8Hz. Honey bee workers use empty cells neighbouring the capped brood cells for brood heating (Kleinhenz et al. 2003). Therefore, bees preferred visiting cells neighboured by numerous brood cells. Both duration of cell visits and thoracic temperature of the bee correlated with the number of neighboured brood cells. Older bees (at least 48h) showed significantly higher thoracic temperatures than younger bees (up to 48h old) immediately before and after their cell visits. Dead capped brood were heated over several days and showed equivalent temperatures to living brood warmed by worker bees. In other cases, the brood temperature was lower, but still in the optimal temperature range of 33.5 to 35°C (Groh et al. 2004). In the experiments, the dead brood was killed by cold then warmed up again to 35°C before putting it into the observation hive. Capped brood cells filled with wax dummies were not heated and immediately cleared out. Mechanical signals from the brood seemed not to be important for the brood heating behaviour of the worker bees; observations with laser-vibrometry showed no signals coming from the brood demanding thermoregulation. The antennae of the bees seem to be very important for effective brood heating, since during brood heating behaviour the antennae point to the capped brood surface. Worker bees with shortened antennae showed inferior brood heating behaviour, while brood temperature correlated with number of missing antenna segments. Additionally, the effectiveness of brood heating seems to be linked to a underlying laterality of the antennas function, when parts of the right antenna were amputated, brood heating was worse than when parts of the left antenna were amputated. With the amputation of the antenna the behaviour of the bees changed: control bees remained very quiet in the capped brood area, while bees with amputated antenna with similarly warm thoraces did not show the typical brood heating behaviour anymore. In some observations brood temperature dropped for some hours and increased again in a way that can only be explained by positive feedback of brood heating of the worker bees. Brood heating appears to be a collective action.