The surface electromyography (SEMG) is one of the most popular bio-signals that can be applied in health monitoring systems, fitness training, and rehabilitation devices. Commercial clothing embedded with textile electrodes has already been released onto the market, but there is insufficient information on the performance of textile SEMG electrodes because the required configuration may differ according to the electrode material. The current study analyzed the influence of electrode size and pattern reduction rate (PRR), and hence the clothing pressure (Pc) based on in vivo SEMG signal acquisition. Bipolar SEMG electrodes were made in different electrode diameters Ø 5–30 mm, and the clothing pressure ranged from 6.1 to 12.6 mmHg. The results supported the larger electrodes, and Pc showed better SEMG signal quality by showing lower baseline noise and a gradual increase in the signal to noise ratio (SNR). In particular, electrodes, Ø ≥ 20 mm, and Pc ≥ 10 mmHg showed comparable performance to Ag-Ag/Cl electrodes in current textile-based electrodes. The current study emphasizes and discusses design factors that are particularly required in the designing and manufacturing process of smart clothing with SEMG electrodes, especially as an aspect of clothing design.
As firefighters’ protective boots induce greater physiological burden when compared with a helmet, gloves or self-contained breathing apparatus, personal protective equipment designers need to consider the improvement of boots in terms of mass reduction, improvement of thermal comfort and ease of doffing during recovery to alleviate physiological strain on firefighters.
The purpose of the present field study was to explore diving patterns and heart rate of
elderly Korean women divers (haenyeo) while breath-hold diving in cold seawater. We
hypothesized that the decreasing rate in heart rate of elderly haenyeos during breath-hold
diving was greater and total diving time was shorter than those of young haenyeos from
previous studies. Nine haenyeos participated in a field study [68 ± 10 yr in age, ranged
from 56 to 83 yr] at a seawater temperature of 10 to 13 °C. Average total diving time
including surface swimming time between dives was 253 ± 73 min (155–341 min). Total
frequency of dives was 97 ± 28 times and they dived 23 ± 8 times per hour. All haenyeos
showed diving bradycardia with a decreased rate of 20 ± 8% at the bottom time (101 ± 20
bpm) when compared to surface swimming time (125 ± 16 bpm) in the sea. Older haenyeos
among the nine elderly haenyeos had shorter diving time, less diving frequencies, and
lower heart rate at work (p<0.05). These reductions imply
that haenyeos voluntarily adjust their workload along with advancing age and diminished
cardiovascular functions.
BackgroundMenthol chemically triggers cold-sensitive receptors in the skin without conductive skin cooling. We investigated the effects of menthol-induced activation of cutaneous cold receptors on the cold-induced vasodilation (CIVD) of the finger. We hypothesized that the menthol application would attenuate typical CIVD responses.Methods1.5% l-menthol was fully applied over the left hand and forearm, and then, the middle finger of the left hand was immersed into 4 °C water for 30 min. A trial consisted of 10-min rest followed by 30-min immersion and 20-min recovery in 28 °C air temperature with 20% relative humidity. Another trial without the menthol application was carried out as a control. Seventeen females (24.2 ± 2.6 years in age, 160.5 ± 5.1 cm in height, and 51.2 ± 5.7 kg in body weight) participated in the two trials.ResultsThe results showed that the maximum and average temperatures of the finger during the water immersion were lower in the menthol application when compared to control (P < 0.05), whereas no significant differences appeared in the onset time of CIVD, the frequency of CIVD, and minimum finger temperature. These results imply that stronger stimulation of cold receptors without additional conductive skin cooling did not attenuate the triggering of CIVD responses but intensified vasoconstriction after the first occurrence of CIVD.ConclusionIt is suggested that substantial and conductive heat loss through the skin along with activation of cold receptors may be required to retain rewarming at a certain level.
The aim of this study was to investigate stable and valid measurement sites of skin temperatures as a non-invasive variable to predict deep-body temperature while wearing firefighters' personal protective equipment (PPE) during air temperature changes. Eight male firefighters participated in an experiment which consisted of 60-min exercise and 10-min recovery while wearing PPE without self-contained breathing apparatus (7.75 kg in total PPE mass). Air temperature was periodically fluctuated from 29.5 to 35.5 °C with an amplitude of 6 °C. Rectal temperature was chosen as a deep-body temperature, and 12 skin temperatures were recorded. The results showed that the forehead and chest were identified as the most valid sites to predict rectal temperature (R(2) = 0.826 and 0.824, respectively) in an environment with periodically fluctuated air temperatures. This study suggests that particular skin temperatures are valid as a non-invasive variable when predicting rectal temperature of an individual wearing PPE in changing ambient temperatures. Practitioner Summary: This study should offer assistance for developing a more reliable indirect indicating system of individual heat strain for firefighters in real time, which can be used practically as a precaution of firefighters' heat-related illness and utilised along with physiological monitoring.
A firefighting simulation was developed in order to assess the physical work capacity of firefighters. The simulation consisted of eight common firefighting tasks, including walking with radiant heat for 3 min while wearing full personal protective equipment (PPE). Nine professional firefighters performed the test a total of three times with a 5 min rest interval between each session. The entire series of tests took approximately 30 min to complete (381 ± 30 s). Rectal temperatures were found to increase from 37.4 ± 0.3 o C to 38.5 ± 0.4 o C, while heart rates were found to increase from 92 ± 18 bpm to 185 ± 13 bpm during testing. Time to completion of the test drills and non-modified physical fitness values showed a significantly negative correlation (r = −0.728, p < 0.05). Firefighters who had longer periods of firefighting service had longer duration time and also recorded higher scores using an integrated scoring system of time to completion (TTC) and physiological strain index (PhSI). The results indicated that the determination of TTC alone can be a misrepresentation of capability, as it neglects to account for accumulated heat strain. The simulated firefighting test provided a useful insight into physical fitness level, but also the comprehensive work capacity of the firefighters when assessed based on TTC and PhSI.
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