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13:30   Thermodynamics in sports products Chair: Stefan Litzenberger 13:30 20 mins THE ZERO HEAT FLUX METHOD AND SWEAT LOSS MODELING IN SPORTS: ATTEMPTS OF NEXT GENERATION SPORTS INFORMATION SYSTEMS Marius Janta, Nadja Höschele, Veit Senner Abstract: Today professional and amateur endurance athletes commonly use biofeedback systems to monitor their training and competition pace. Body core temperature and sweat loss are crucial factors influencing physical capabilities. Unfortunately, current gold standards are invasive and therefore impractical in active situations. Several non-intrusive technologies or models have been proposed, but partially are still unsuitable for active applications, not user friendly or lack knowledge on physiological relations. This paper is a first attempt for new information systems in sports and primarily assesses the Zero Heat Flux Method (ZHF) compared to aural temperatures during activity in two environments and four body sites. Furthermore, sweat loss has been analysed in various controlled experiments presented as simple modelling approach. Results showed that during activity in this set up, optimally 66% of differences in the zero heat flux method were within common core temperature deviations of ±0.5°C. Deviations varied highly across sites, the two conditions and individuals. The same is reflected from relations between body core temperature and sweat loss, since correlation coefficients increase with a more detailed subgrouping. In conclusion, it seems that slight modifications on the sensor assembly e.g. on insulation and size could partially solve remaining deviations. On contrast it´s likely that skin wetness remains a problem. Due to manifold individual and environmental influences on sweat rate, insufficient technologies and impracticable models, it remains unclear how sweat loss could be reliably measured or predicted. From today’s knowledge a further attempt could be using local sweat composition as predictor of blood sodium levels that potentially could describe hypo- and even hyper-hydration. 13:50 20 mins CONCEPTUAL DEVELOPMENT AND EVALUATION OF HEAT RELIEF PROTOTYPES FOR BICYCLE HELMETS Stefanie Passler, Jürgen Mitternacht, Marius Janta, Veit Senner Abstract: The head is one of the most heat sensitive parts of the human body. In various sports head protection is obligatory resulting in a dilemma. In situations of high metabolism heat is accumulated due to insulation properties of the helmet, leading to enormous heat stress and discomfort. Today one way to improve heat dissipation from the head is via ventilation openings. But thermodynamically, further opportunities exist either active or passive. In this paper one material- and one technology-based concept are presented and evaluated with a physical thermal head model. The former uses evaporative cooling (convection). It consists of a water reservoir, a small pump to transport the water beneath the helmet, tubes and a textile for a homogeneous water distribution. The second uses materials with beneficial conductive properties (conduction) in direct contact to the head. This concept is realized by the use of heat pipes that are integrated in the structure of the helmet and a heat sink. Cooling effect of the concepts is evaluated in two controlled thermal environments (T1=15°C; T2=28°C; RH=70%). Thereby the head is heated up to a constant inner temperature of Thy=39°C that arises during high activity. The surface temperatures on the head are recorded by 61 evenly distributed temperature sensors, representing skin temperatures. Finally, cooling effect results from the heating energy that is needed to keep a constant core temperature. The analysed data relating to the required heating energy shows no differences between the HRSs and compared to the reference measurement. In contrast, a considerable effect of HRSs is determined, locally. Applying the HRS Heat pipe & Heat sink skin temperatures show decreases both at 15°C and at 28°C compared to the reference measurement. At sensor position 3 the maximum decrease can be seen by 25 %. By using the HRS H2O at especially sensor position 3 skin temperature decreases by 13 % at 15°C and by 8 % at 28°C in comparison to the values of the reference measurement. Concerning the cooling effect, the comparison of both of the HRSs shows up to 17 % better values at 15°C using the HRS Heat pipe & Heat sink. At 28°C no differences can be seen. Concerning the cooling effect and the disadvantages of the evaporative cooling principle, the HRS Heat Pipe & Heat sink is more suited for such an application in bicycle helmets. For applying this HRS to a bicycle helmet it has to be adapted to the entire helmet and to its shape. 14:10 20 mins FRICTIONAL INTERACTION BETWEEN RUNNING SOCK FABRICS AND PLANTAR ASPECT OF FIRST METATARSAL HEAD IN DIFFERENT MOISTURE CONDITIONS. Diyana Tasron, Raman Maiti, Matthew Hemming, Roger Lewis, Matt Carré Abstract: It is widely acknowledged that the presence of water in the skin-fabric interface can have an effect on the friction level between these two surfaces. Many previous studies have investigated this topic in the context of friction blister formation. However most of these studies were conducted on the forearm skin at a fairly low range of normal loads. In a pursuit to further improve the understanding of the factors influencing friction blister formation, frictional interaction between running sock fabrics and the skin at the first metatarsal head (1MTH) was investigated in three different moisture conditions (dry, low moisture and wet). Twenty-six participants were recruited for the purpose of this study and two running sock types were selected based on the variations of their fibre composition and knit structure: 1) a predominantly nylon anti-blister sock and 2) a cotton-rich sock. All friction tests were conducted in controlled room conditions using a bespoke rig developed at the University of Sheffield for foot friction studies. Water was applied to the inside of the plantar region of the sock fabrics to different levels using a controlled approach. The moisture level of both the 1MTH and the sock fabrics were monitored throughout testing using a Corneometer® CM825 device (Courage and Khazaka). No significant trend was observed between the friction and the baseline moisture level of the 1MTH (i.e. measured after the foot had been cleaned and acclimatised to the ambient conditions). However, it was found that there was a significant difference between the friction levels of the two running sock types at all three moisture conditions. In dry condition, the cotton-rich sock exhibited lower levels of friction compared with the anti-blister sock. However, in both low moisture and wet conditions, the anti-blister sock showed comparatively lower levels of friction. This suggests that for intensive athletic events where significant sweating is known to occur, the anti-blister sock would provide lower friction than the cotton-rich sock. This study offers a new approach to friction testing against sock fabrics and it is hoped that its outcomes will provide new insights on the preventative measures for friction blisters.