Kleding en mode: een kritisch wetenschappelijke beschouwing

Kleding vormt de interface tussen het menselijk lichaam en de leefomgeving. Kleding geeft mensen de mogelijkheid om hun identiteit en culturele achtergrond uit te drukken. Daarnaast heeft kleding vaak een beschermende rol, vooral tegen extreme weersomstandigheden zoals hoge en lage temperatuur, neerslag, wind, zonnestraling, maar ook tegen vuil, gifgas, kogels (zogenaamde ballistische bescherming), stoten, extreme druk, explosies e.d. Soms is kleding juist nodig om de omgeving af te schermen tegen vuil dat de mens produceert, zoals bij de productie van computerelektronica. Onder kleding wordt in deze verhandeling al het materiaal verstaan dat het menselijk lichaam omhult. Globaal betreft het voor het hoofd een hoofddeksel, voor de handen handschoenen of wanten, voor de voeten sokken en schoenen. Voor het boven- en onderlijf is meer keuze beschikbaar zoals een hemd, bh, Tshirt, polo, overhemd, trui, jas, onderbroek, broek en rok. Er zijn ook kledingstukken die boven- en onderlijf omspannen zoals een jurk, overall en lange jas. Bovendien is er een grote variatie binnen een categorie kledingstukken; hierbij kan onderscheid gemaakt worden in vorm, materiaal en kleur. In het lectoraat is gekozen voor drie speerpunten van onderzoek voor kleding/mode. Deze speerpunten zijn tot stand gekomen op basis van aanwezige expertise in de kenniskring van het lectoraat, analyse van kennislacunes en een inschatting van potentieel relevante maatschappelijke ontwikkelingen

Endothermic salts integrated in impermeable suits do not reduce heat strain during exercise

Wearing impermeable garments during work inherently leads to heat strain, even in cold environments [1]. Phase change materials (mainly paraffin’s or salt [4]) may be used as a thermal buffer (e.g. [2]) to reduce initial heat stress. Salts can also be used to absorb sweat, which may enhance the cooling power from the skin. Recently, specific encapsulated salts utilising KSCN (potassium thiocyanate) have been developed that consume energy when the KSCN dissolves in water. The heat consumed when the KSCN (present inside 150 g of capsules containing 60% KSCN salt) dissolves in water is 22410 J (249 J/g * 60% * 150 g). When this solving takes place over a period of 30 minutes, the average power transfer is 12 W. One (1) g of KSCN-containing capsules absorbs close to 1 g of moisture. If we assume that 150 g sweat extra can be evaporated from the skin, this yields an extra cooling power of 182 W for 30 minutes. However this evaporated water from the skin is subsequently absorbed by the KSCN in the capsules. During this absorption from the gas phase, the condensation heat is released to the KSCN salt: about 182 W for 30 minutes. However, we hypothesise that this condensation heat will be partly transferred to the body and partly to the environment [3], providing a net benefit to the body. Thus, the total cooling effect due to the salt capsules is composed of two parts: • The cooling effect of about 12 W due to the heat consumption by the dissolving of the salts in water; • The cooling effect of maximal 182 W, which equals the difference between the evaporative heat and the condensation heat. The latter is generated in the salt capsules that transfer part of the heat to the environment. The overall cooling effect should therefore be in between 12 W and 194 W. The purpose of our study was to test the efficacy of a KSCN-based absorbing salt as a PCM for use within impermeable protective clothing. We tested the PCM during 20 min of moderate exercise in a hot (35°C, 40% relative humidity) environment, and hypothesized that thermal strain would be lower in the PCM compared to the non-PCM condition

A systematic review on heart-rate recovery to monitor changes in training status in athletes

Heart-rate recovery (HRR) has been proposed as a marker of autonomic function and training status in athletes. The authors performed a systematic review of studies that examined HRR after training. Five cross-sectional studies and 8 studies investigating changes over time (longitudinal) met our criteria. Three out of 5 crosssectional studies observed a faster HRR in trained compared with untrained subjects, while 2 articles showed no change as a result of training. Most longitudinal studies observed a corresponding increase in HRR and power output (training status). Although confounding factors such as age, ambient temperature, and the intensity and duration of the exercise period preceding HRR make it difficult to compare these studies, the available studies indicated that HRR was related to training status. Therefore, the authors conclude that HRR has the potential to become a valuable tool to monitor changes in training status in athletes and less well-trained subjects, but more studies and better standardization are required to match this potential

Effect of warm-up and precooling on pacing during a 15-km cycling time trial in the heat

PURPOSE:The best way to apply precooling for endurance exercise in the heat is still unclear. Therefore, we analyzed the effect of different preparation regimes on pacing during a 15-km cycling time trial in the heat.METHODS:Ten male subjects completed four 15-km time trials (30°C), preceded by different preparation regimes: 10 min cycling (WARM-UP), 30 min scalp cooling of which 10 min cycling (SC+WARM-UP), ice slurry ingestion (ICE), and ice slurry ingestion + 30 min scalp cooling (SC+ICE).RESULTS:No differences were observed in finish time and mean power output, although power output was lower for WARM-UP than for SC+ICE during km 13-14 (17±16 and 19±14 W, respectively) and for ICE during km 13 (16±16 W). Rectal temperature at the start of the time trial was lower for both ICE (~36.7°C) than both WARM-UP (~37.1°C) conditions and remained lower during the first part of the trial. Skin temperature and thermal sensation were lower at the start for SC+ICE.CONCLUSIONS:The preparation regime providing the lowest body heat content and sensation of coolness at the start (SC+ICE) was most beneficial for pacing during the latter stages of the time trial, although overall performance did not differ

Clinical Gait Analysis : A review of research at the interdepartmental research group of kinesiology in Leiden

In dit artikel worden de methoden beschreven die de Werkgroep voor Bewegingsanalyse van de Rijksuniversiteit Leiden gebruikt om het menselijk gangbeeld te kwantificeren. De vier beschreven methoden zijn: analyse van tijdparameters, hoekmeting, versnellingsmeting en elektromyografie. Een juiste weergave van elektromyografische gegevens en ook van hoeken, hangt af van de wijze waarop deze gegevens zijn gesynchroniseerd. Indien gebruik wordt gemaakt van alle, in de loopcyclus voorhanden, synchronisatiepunten is de fout rondom de curve het geringst. Men moet dan wel de nodige maatregelen treffen om een juiste tijdas te verkrijgen. Combineren van de beschreven methoden levert soms extra informatie op die gebruikt kan worden om het inzicht in het menselijk gangbeeld te verdiepen

Manual performance deterioration in the cold estimated using the wind chill equivalent temperature

Manual performance during work in cold and windy climates is severely hampered by decreased dexterity, but valid dexterity decrease predictors based on climatic factors are scarce. Therefore, this study investigated the decrease in finger- and hand dexterity and grip force for nine combinations of ambient temperature (-20, -10 and 0°C) and wind speeds (0.2, 4 and 8 m-s2), controlled in a climatic chamber. Finger dexterity was determined by the Purdue pegboard test, hand dexterity by the Minnesota manual dexterity test and grip force by a hand dynamometer. Twelve subjects with average to low fat percentage were exposed to cold air for one hour with and without extra insulation by a parka. The subjects were clothed in standard work clothing of the Royal Netherlands Air Force for cold conditions. Extra insulation did affect cold sensation but not manual performance. The deterioration in manual performance appeared to be strongly dependent upon Wind Chill Equivalent Temperature (WCET) and the square root of exposure time (r=0.93 for group average). These simple models may be valuable to assess problems with work in the cold, but more work should be done to determine critical values in dexterity for a wide variety of operational tasks

3-D surface anthropometry ; accurate determination of body dimensions

Body dimensions of the user population have to be the starting point of design and evaluation of many workplaces and products. Insufficient attention to these aspects may lead to uncomfortable, unhealthy, or dangerous situations. Few up-to-date anthropometric databases are available. The shortage of anthropometric databases may in part be attributed to the time consuming and expensive traditional measurement techniques. 3-D surface scanning seems a good alternative: it is cheaper for large scale surveys, fast, reliable and yields reproducible results. Some challenges remain: reduction of human movement artifacts, optimisation of body postures during the scan, development of dedicated software to process the data. The whole body scans have applications mainly in three areas: improvement of fit of clothing and equipment, improvement of workplace design and evalua-tion, and a variety of medical applications. It can be expected that in the near future new and comprehensive databases of human dimensions emerge