Effect of Clothing Fabric on 20-km Cycling Performance in Endurance Athletes

Purpose: Examine the effect of synthetic fabrics (SYN, 60% polyester: 40% nylon) vs. 100% cotton fabric (CTN) on the 20-km cycling time trial (20 kmCTT) performance of competitive cyclists and triathletes.Methods: In this randomized controlled crossover study, 15 adults (5 women) aged 29.6 ± 2.7 years (mean ± SE) with a peak rate of O2 consumption of 60.0 ± 2.0 ml/kg/min completed a 20 kmCTT under ambient laboratory conditions (24.3 ± 0.7°C and 17 ± 7% relative humidity) with a simulated wind of ~3 m/s while wearing SYN or CTN clothing ensembles. Both ensembles were of snowflake mesh bi-layer construction and consisted of a loose-fitting long-sleeved shirt with full-length trousers.Results: Participants maintained a significantly (p < 0.05) higher cycling speed and power output over the last 6-km of the 20 kmCTT while wearing the SYN vs. CTN ensemble (e.g., by 0.98 km/h and 18.4 watts at the 20-km mark). Consequently, 20 kmCTT duration was significantly reduced by 15.7 ± 6.8 sec or 0.8 ± 0.3% during SYN vs. CTN trials (p < 0.05). Improved 20 kmCTT performance with SYN vs. CTN clothing could not be explained by concurrent differences in esophageal temperature, sweat rate, ratings of perceived exertion and/or cardiometabolic responses to exercise. However, it was accompanied by significantly lower mean skin temperatures (~1°C) and more favorable ratings of perceived clothing comfort and thermal sensation during exercise.Conclusion: Under the experimental conditions of the current study, athletic clothing made of synthetic fabrics significantly improved the 20 kmCTT performance of endurance-trained athletes by optimizing selected thermoregulatory and perceptual responses to exercise.

Osmotically Enabled Wearable Patch for Sweat Harvesting and Lactate Quantification

Lactate is an essential biomarker for determining the health of the muscles and oxidative stress levels in the human body. However, most of the currently available sweat lactate monitoring devices require external power, cannot measure lactate under low sweat rates (such as in humans at rest), and do not provide adequate information about the relationship between sweat and blood lactate levels. Here, we discuss the on-skin operation of our recently developed wearable sweat sampling patch. The patch combines osmosis (using hydrogel discs) and capillary action (using paper microfluidic channel) for long-term sweat withdrawal and management. When subjects are at rest, the hydrogel disc can withdraw fluid from the skin via osmosis and deliver it to the paper. The lactate amount in the fluid is determined using a colorimetric assay. During active sweating (e.g., exercise), the paper can harvest sweat even in the absence of the hydrogel patch. The captured fluid contains lactate, which we quantify using a colorimetric assay. The measurements show the that the total number of moles of lactate in sweat is correlated to sweat rate. Lactate concentrations in sweat and blood correlate well only during high-intensity exercise. Hence, sweat appears to be a suitable biofluid for lactate quantification. Overall, this wearable patch holds the potential of providing a comprehensive analysis of sweat lactate trends in the human body.

Kajian Pengaruh Heat Stress terhadap Beban Kerja Fisik Berat pada Kegiatan Lapangan

Penelitian ini merupakan studi pendahuluan terhadap pengaruh tekanan panas terhadap beban kerja berat pada kegiatan lapangan, mengingat Indonesia sebagai negara tropis memiliki suhu dan kelembaban udara tinggi. Cuaca panas, yang dapat menyebabkan heat stress, merupakan beban bagi tubuh dan semakin berat pada aktivitas fisik berat. Eksperimen dilakukan terhadap 20 partisipan (10 orang pria, 10 orang wanita) yang melakukan pekerjaan dengan intensitas kerja tinggi selama 30 menit di lapangan dengan iklim ekstrim. Beban kerja dilihat berdasarkan denyut jantung dan berat badan untuk melihat energy expenditure, intensitas kerja, dan sweat rate. Hasil pengukuran menunjukkan beban kerja pada eksperimen ini termasuk dalam kategori tinggi/berat. Iklim lapangan diukur berdasarkan indeks WBGT, dan hasil pengukuran menunjukkan bahwa indeks WBGT selama eksperimen adalah 31°C (87.9°F), termasuk dalam kategori berisiko tekanan panas sangat tinggi. Hasil penelitian menunjukkan bahwa iklim tidak berpengaruh terhadap energy expenditure, akan tetapi berpengaruh terhadap energy expenditure pada partisipan wanita (p<0.05). Iklim juga berpengaruh terhadap intensitas kerja (p<0.05), sedangkan sweat rate tidak dapat digunakan untuk menghitung beban kerja karena waktu eksprimen tidak cukup meningkatkan panas tubuh dan hanya berdasarkan berat badan. Penelusuran lebih seksama terhadap model estimasi expenditure yang digunakan dalam sebuah eksperimen diperlukan agar sesuai dengan karakteristik pekerjaan.

The effect of extracellular hyperosmolality on sweat rate during metaboreflex activation in passively heated young men

Metaboreflex activation augments sweating during mild-to-moderate hyperthermia in euhydrated (isosmotic isovolemic) individuals. Recent work indicates that extracellular hyperosmolality may augment metaboreflex-mediated elevations in sympathetic nervous activity. Our primary objective was therefore to test the hypothesis that extracellular hyperosmolality would exacerbate metaboreflex-mediated increases in sweat rate. On two separate occasions, 12 young men (mean (SD): 25 (5) years) received a 90-min intravenous infusion of either 0.9% saline (isosmotic condition, ISO) or 3.0% saline (hyperosmotic condition, HYP), resulting in a post-infusion serum osmolality of 290 (3) and 301 (7) mOsm/kg, respectively. A whole-body water perfusion suit was then used to increase esophageal temperature by 0.8°C above resting. Participants then performed a metaboreflex activation protocol consisting of 90 s isometric handgrip exercise (40% of their pre-determined maximum voluntary contraction), followed by 150 s of brachial occlusion (trapping produced metabolites within the limb). Metaboreflex-induced sweating was quantified as the change in global sweat rate (from pre-isometric handgrip exercise to brachial occlusion), estimated as the surface area-weighted average of local sweat rate on the abdomen, axilla, chest, bicep, quadriceps, and calf, measured using ventilated capsules (3.8 cm2). We also explored whether this response differed between body regions. The change in global sweat rate due to metaboreflex activation was significantly greater in HYP compared to ISO (0.03 mg/min/cm2 [95% confidence interval: 0.00, 0.06]; p=0.047), but was not modulated by body region (site*condition interaction: p=0.679). These findings indicate that extracellular hyperosmolality augments metaboreflex-induced increases in global sweat rate, with no evidence for region-specific differences.

Exercise Heat Acclimation With Dehydration Does Not Affect Vascular and Cardiac Volumes or Systemic Hemodynamics During Endurance Exercise

Permissive dehydration during exercise heat acclimation (HA) may enhance hematological and cardiovascular adaptations and thus acute responses to prolonged exercise. However, the independent role of permissive dehydration on vascular and cardiac volumes, ventricular-arterial (VA) coupling and systemic hemodynamics has not been systematically investigated. Seven males completed two 10-day exercise HA interventions with controlled heart rate (HR) where euhydration was maintained or permissive dehydration (-2.9 ± 0.5% body mass) occurred. Two experimental trials were conducted before and after each HA intervention where euhydration was maintained (-0.5 ± 0.4%) or dehydration was induced (-3.6 ± 0.6%) via prescribed fluid intakes. Rectal (Tre) and skin temperatures, HR, blood (BV) and left ventricular (LV) volumes, and systemic hemodynamics were measured at rest and during bouts of semi-recumbent cycling (55% V̇O2peak) in 33°C at 20, 100, and 180 min. Throughout HA sweat rate (12 ± 9%) and power output (18 ± 7 W) increased (P &lt; 0.05), whereas Tre was 38.4 ± 0.2°C during the 75 min of HR controlled exercise (P = 1.00). Neither HA intervention altered resting and euhydrated exercising Tre, BV, LV diastolic and systolic volumes, systemic hemodynamics, and VA coupling (P &gt; 0.05). Furthermore, the thermal and cardiovascular strain during exercise with acute dehydration post-HA was not influenced by HA hydration strategy. Instead, elevations in Tre and HR and reductions in BV and cardiac output matched pre-HA levels (P &gt; 0.05). These findings indicate that permissive dehydration during exercise HA with controlled HR and maintained thermal stimulus does not affect hematological or cardiovascular responses during acute endurance exercise under moderate heat stress with maintained euhydration or moderate dehydration.

Upper Body of Dynamic Sweat Distributions in Young Males Wearing Fully Encapsulating Chemical Protective Ensembles

Fully encapsulating chemical protective ensembles (FCPE) has characteristic of impermeability, which may affect people’s sweat, accordingly influences clothing thermal-wet comfort. This study investigated upper-body dynamic sweat distribution in young males wearing FCPE, and evaluating changes in sweat rates both intra-region and inter-time. Participants were 10 healthy young male college students, aged 23.1\(\pm\)0.8 years. In a climatic chamber (environment temperature 35 ℃, relative humidity 60%), participants exercised on a treadmill at 4 km/h, 5%. A set of absorbent pads with 35 pads was used to collect sweat. Participants change a new set of absorbent pads every 5 minutes until trial stopped. Seven sets of pads were obtained. Average sweat rate of every 5 minutes is 389, 631, 920, 1137, 1100, 1211 and 1105 g.m−2.h−1, respectively. The top five high sweat rates were observed at the medial upper back, lateral lower back, medial upper chest, medial mid back and lateral top back, with average values 1406,1278,1198,1181 and 1139 g·m−2·h−1, respectively. The lower sweat rates were observed at waist (with average values 557, 370, 596 and 332 g·m−2·h−1, respectively) and bottom zones (with average values 373, 398, 661 and 849 g·m−2·h−1, respectively). Wearing FCPE greatly promoted body profuse sweating. Based on the distribution result, upper body can be divided into three levels of sweat rate zones, which could be used to improve clothing comfort. The present study provides basic physiological data and guidance for personal protective clothing design.

Enhancing sweat rate using a novel device for the treatment of congestion in heart failure

Background Current treatment of fluid retention in heart failure (HF) relies primarily on diuretics. However, adequate decongestion is not achieved in many patients. Purpose To study the feasibility and short-term performance of a novel approach to remove fluids and sodium directly from the interstitial compartment by enhancing sweat rate. Methods We used a device designed to enhance fluid and salt loss via the eccrine sweat glands. Skin temperature in the lower body was increased to 35–38°, where the slope of the relationship between temperature and sweat production is linear. With this wearable device, the sweat evaporates instantaneously, thus avoiding the awareness of perspiration. The primary efficacy endpoint was the ability to increase skin temperature to the desired range without elevating the core temperature above normal range. A secondary efficacy endpoint was a clinically meaningful hourly sweat output, defined as ≥150 mL/h. The primary safety endpoint was any procedure-related adverse events. Results We studied 6 normal subjects and 10 HF patients with clinical evidence of congestion and median NT-proBNP of 602 pg/mL [interquartile range 427 to 1719 pg/mL]. Participants underwent 3 treatment sessions of up to 4h. Skin temperature increased to a median of 37.5°C (interquartile range 37.1–37.9°C) with the core temperature remaining unchanged. The median total weight loss during treatment was 219±67 g/h (Figure) with a range of 100–338 g/h. In 77% of cases, the average sweat rate was ≥150 mL/h. Systolic (P=0.25) and diastolic (P=0.48) blood pressure and heart rate (P=0.11) remained unchanged during the procedure. There were no significant changes in renal function and no procedure-related adverse events. Conclusion Enhancing sweat rate was safe and resulted in a clinically meaningful fluid removal and weight loss. Further evaluation of this concept is warranted. FUNDunding Acknowledgement Type of funding sources: Private company. Main funding source(s): AquaPass Inc Weight loss due to sweat

Intervention of Hydration Protocol on Strength, Endurance, and Muscle Power Performance

Water is a molecule that plays an essential role in the muscle contraction process because muscle is a tissue that mostly contains water (75-80%). Therefore, athletes need to maintain fluid intake to support their physical activities when competing and when training. Nevertheless, in several studies, it was noted that some athletes experienced hypohydration or dehydration, which ultimately impaired muscle performance. Therefore, this study was conducted to determine the hydration protocol intervention on muscle strength, endurance, and power performance. This research is an analytical study with quasi-experimental research methods, namely single-arm pre-post study design using secondary data. Subjects of this study were 69 athletes year 2020 (named consecutively: Muaythai 9, Pencak silat 12, wrestling 10, judo 18, and taekwondo 20 athletes). This research was conducted from December 2019 to January 2020. In the beginning, all athletes were tested for muscle strength using a leg dynamometer, then muscle endurance tests using push-up and sit-up tests, and muscle power tests using the triple hop test of the right and left legs. After the first test, all athletes were educated about the hydration protocol. The hydration protocol was determined based on each athlete's sweat rate (ISR) and the training characteristics of each sports division. Then, all athletes underwent the training for two months. After that, the same tests were performed. The result showed that hydration protocol influenced the performance of muscle strength, endurance, and power. Therefore, the hydration protocol is influential in maintaining a good hydration status in athletes so that the athlete does not experience hypohydration which will later impair the athlete's muscle performance. Therefore, it is crucial to apply hydration protocols individually according to the training program (volume of training), not only in martial arts sports but in all sports.

Body mapping of sweating patterns of pre-pubertal children during intermittent exercise in a warm environment

Purpose To determine sweating responses of pre-pubertal children during intermittent exercise in a warm environment and create whole-body maps of regional sweat rate (RSRs) distribution across the body. Methods Thirteen pre-pubertal children; six girls and seven boys (8.1 ± 0.8 years) took part. Sweat was collected using the technical absorbent method in the last 5 min of a 30-min intermittent exercise protocol performed at 30 ℃, 40% relative humidity and 2 m·s−1 frontal wind. Results Mean gross sweat loss (GSL) was 126 ± 47 g·m−2·h−1 and metabolic heat production was 278 ± 50 W·m2. The lower anterior torso area had the lowest RSR with a median (IQR) sweat rate (SR) of 40 (32) g·m−2·h−1. The highest was the forehead with a median SR of 255 (163) g·m−2·h−1. Normalised sweat maps (the ratio of each region’s SR to the mean SR for all measured pad regions) showed girls displayed lower ratio values at the anterior and posterior torso, and higher ratios at the hands, feet and forehead compared to boys. Absolute SRs were similar at hands and feet, but girls sweated less in most other areas, even after correction for metabolic rate. Conclusion Pre-pubertal children have different RSRs across the body, also showing sex differences in sweat distribution. Distributions differ from adults. Hands and feet RSR remain stable, but SR across other body areas increase with maturation. These data can increase specificity of models of human thermoregulation, improve the measurement accuracy of child-sized thermal manikins, and aid companies during product design and communication.