Metabolic, Cardiac, and Hemorheological Responses to Submaximal Exercise under Light and Moderate Hypobaric Hypoxia in Healthy Men.

We compared the effects of metabolic, cardiac, and hemorheological responses to submaximal exercise under light hypoxia (LH) and moderate hypoxia (MH) versus normoxia (N). Ten healthy men (aged 21.3 ± 1.0 years) completed 30 min submaximal exercise corresponding to 60% maximal oxygen uptake at normoxia on a cycle ergometer under normoxia (760 mmHg), light hypoxia (596 mmHg, simulated 2000 m altitude), and moderate hypoxia (526 mmHg, simulated 3000 m altitude) after a 30 min exposure in the respective environments on different days, in a random order. Metabolic parameters (oxygen saturation (SPO2), minute ventilation, oxygen uptake, carbon dioxide excretion, respiratory exchange ratio, and blood lactate), cardiac function (heart rate (HR), stroke volume, cardiac output, and ejection fraction), and hemorheological properties (erythrocyte deformability and aggregation) were measured at rest and 5, 10, 15, and 30 min after exercise. SPO2 significantly reduced as hypoxia became more severe (MH > LH > N), and blood lactate was significantly higher in the MH than in the LH and N groups. HR significantly increased in the MH and LH groups compared to the N group. There was no significant difference in hemorheological properties, including erythrocyte deformability and aggregation. Thus, submaximal exercise under light/moderate hypoxia induced greater metabolic and cardiac responses but did not affect hemorheological properties.

Physical Characteristics and Physical Fitness Profiles of Korean Taekwondo Athletes: A Systematic Review.

This study aimed to present a standard and normal distribution of Taekwondo athletes' physical characteristics and physical fitness profiles using a systematic review. A systematic search was conducted using four Korean databases (Research Information Sharing Service, National Digital Science Library, DBpia, and Korean Studies Information Service System). From 2010 to 2020, we reviewed 838 papers on Taekwondo athletes' physical characteristics and physical fitness factors (e.g., body composition, muscle strength, muscular endurance, flexibility, cardiorespiratory fitness, power, agility, balance, speed, and reaction time). Of them, 24 papers were selected and analyzed. The criteria for selecting the physical characteristics and physical fitness factors for data extraction were set to have a total sample size of more than 30 individuals and included two or more studies. The sample size and average and standard deviation of physical characteristics and physical fitness factors were extracted from each selected study. In this study, the estimation error of all variables, except for the eyes-closed single-leg stance (15.71%), was less than 8%. Therefore, it was confirmed that there was no problem with the validity of the estimated values. These results could be used as an essential objective basis for evaluating the physical characteristics and physical fitness profiles of Taekwondo athletes in most countries worldwide and setting training goals.

Estimated Artificial Neural Network Modeling of Maximal Oxygen Uptake Based on Multistage 10-m Shuttle Run Test in Healthy Adults.

We aimed to develop an artificial neural network (ANN) model to estimate the maximal oxygen uptake (VO2max) based on a multistage 10 m shuttle run test (SRT) in healthy adults. For ANN-based VO2max estimation, 118 healthy Korean adults (59 men and 59 women) in their twenties and fifties (38.3 ± 11.8 years, men aged 37.8 ± 12.1 years, and women aged 38.8 ± 11.6 years) participated in this study; data included age, sex, blood pressure (systolic blood pressure (SBP), diastolic blood pressure (DBP)), waist circumference, hip circumference, waist-to-hip ratio (WHR), body composition (weight, height, body mass index (BMI), percent skeletal muscle, and percent body), 10 m SRT parameters (number of round trips and final speed), and VO2max by graded exercise test (GXT) using a treadmill. The best estimation results (R2 = 0.8206, adjusted R2 = 0.7010, root mean square error; RMSE = 3.1301) were obtained in case 3 (using age, sex, height, weight, BMI, waist circumference, hip circumference, WHR, SBP, DBP, number of round trips in 10 m SRT, and final speed in 10 m SRT), while the worst results (R2 = 0.7765, adjusted R2 = 0.7206, RMSE = 3.494) were obtained for case 1 (using age, sex, height, weight, BMI, number of round trips in 10 m SRT, and final speed in 10 m SRT). The estimation results of case 2 (using age, sex, height, weight, BMI, waist circumference, hip circumference, WHR, number of round trips in 10 m SRT, and final speed in 10 m SRT) were lower (R2 = 0.7909, adjusted R2 = 0.7072, RMSE = 3.3798) than those of case 3 and higher than those of case 1. However, all cases showed high performance (R2) in the estimation results. This brief report developed an ANN-based estimation model to predict the VO2max of healthy adults, and the model's performance was confirmed to be excellent.

Trends in Korean parents' perceptions on food additives during the period 2014-2018.

BACKGROUND/OBJECTIVES: While the use of food additives in food processing has become a common practice worldwide, consumers' worry about potential hazards has not diminished. The purpose of this study was to identify trends in South Korean parents' perceptions about food additives by analyzing the results of surveys conducted from 2014 to 2018. SUBJECTS/METHODS: We conducted an off-line survey in Korea annually between 2014 and 2018 on perceptions about food additives. The numbers of survey respondents in each year from 2014 to 2018 were 381, 426, 301, 519, and 369, respectively. Our consumer respondents were parents of elementary-school-aged children. RESULTS: The ratios of respondents perceiving "food safety" as the most important factor in purchasing processed foods and "food additives" as the biggest threat to food safety have decreased over the years. However, most consumers still have negative perceptions of food additives. Additionally, among consumers lower confidence in or trust of the Korean government continued throughout the study period and appeared to be the main problem that needs to be overcome. CONCLUSIONS: This study found that Korean parents are still troubled by food additives. Consumers' confidence in the government needs to be increased through public communications. More multifaceted educational programs communicating scientific knowledge of food additives are needed in order to correct consumers' misperceptions.

Aerobic Continuous and Interval Training under Hypoxia Enhances Endurance Exercise Performance with Hemodynamic and Autonomic Nervous System Function in Amateur Male Swimmers.

Hypoxic training is often performed by competitive swimmers to enhance their performance in normoxia. However, the beneficial effects of aerobic continuous and interval training under hypoxia on hemodynamic function, autonomic nervous system (ANS) function, and endurance exercise performance remain controversial. Here we investigated whether six weeks of aerobic continuous and interval training under hypoxia can improve hematological parameters, hemodynamic function, ANS function, and endurance exercise performance versus normoxia in amateur male swimmers. Twenty amateur male swimmers were equally assigned to the hypoxic training group or normoxic training group and evaluated before and after six weeks of training. Aerobic continuous and interval training in the hypoxia showed a more significantly improved hemodynamic function (heart rate, -653.4 vs. -353.7 beats/30 min; oxygen uptake, -62.45 vs. -16.22 mL/kg/30 min; stroke volume index, 197.66 vs. 52.32 mL/30 min) during submaximal exercise, ANS function (root mean square of successive differences, 10.15 vs. 3.32 ms; total power, 0.72 vs. 0.20 ms2; low-frequency/high-frequency ratio, -0.173 vs. 0.054), and endurance exercise performance (maximal oxygen uptake, 5.57 vs. 2.26 mL/kg/min; 400-m time trial record, -20.41 vs. -7.91 s) than in the normoxia. These indicate that hypoxic training composed of aerobic continuous and interval exercise improves the endurance exercise performance of amateur male swimmers with better hemodynamic function and ANS function.

Resistance Training in Hypoxia as a New Therapeutic Modality for Sarcopenia-A Narrative Review.

Hypoxic training is believed to be generally useful for improving exercise performance in various athletes. Nowadays, exercise intervention in hypoxia is recognized as a new therapeutic modality for health promotion and disease prevention or treatment based on the lower mortality and prevalence of people living in high-altitude environments than those living in low-altitude environments. Recently, resistance training in hypoxia (RTH), a new therapeutic modality combining hypoxia and resistance exercise, has been attempted to improve muscle hypertrophy and muscle function. RTH is known to induce greater muscle size, lean mass, increased muscle strength and endurance, bodily function, and angiogenesis of skeletal muscles than traditional resistance exercise. Therefore, we examined previous studies to understand the clinical and physiological aspects of sarcopenia and RTH for muscular function and hypertrophy. However, few investigations have examined the combined effects of hypoxic stress and resistance exercise, and as such, it is difficult to make recommendations for implementing universal RTH programs for sarcopenia based on current understanding. It should also be acknowledged that a number of mechanisms proposed to facilitate the augmented response to RTH remain poorly understood, particularly the role of metabolic, hormonal, and intracellular signaling pathways. Further RTH intervention studies considering various exercise parameters (e.g., load, recovery time between sets, hypoxic dose, and intervention period) are strongly recommended to reinforce knowledge about the adaptational processes and the effects of this type of resistance training for sarcopenia in older people.

Perception Gaps on Food Additives among Various Groups in Korea: Food Experts, Teachers, Nutrition Teachers, Nongovernmental Organization Members, and General Consumers.

The purpose of this study was to determine the perceptions and information needs of food experts, teachers, nutrition teachers, members of nongovernmental organizations, and general consumers concerning food additives. Questions in a survey format included perceptions, information needs, and preferred communication channels. The survey was conducted both off-line and on-line via e-mail and Google Drive in March 2015. The results indicated that most Korean consumers are concerned about the safety of using food additives in processed foods and do not recognize these additives as safe and useful materials as part of a modern diet. We also identified perception gaps among different groups regarding food additives. Nutrition teachers and members of nongovernmental organizations in Korea appeared to have a biased perception of food additives, which may cause general consumers to have a negative perception of food additives. The group of food experts did not have this bias. Governmental institutions must overcome the low confidence levels of various groups as an information provider about food additives. Based on the findings in this study, it will be possible to develop a strategy for risk communication about food additives for each group.

Development of Safe Food Handling Guidelines for Korean Consumers.

The purpose of this study was to develop guidelines for Korean consumers with regard to safe food handling practices at home by identifying current food handling issues. Korean consumers' behaviors regarding their safe food handling were identified via survey questionnaires that included items on individual hygiene practices, prepreparation steps when cooking, the cooking process, and the storage of leftover foods. The subjects were 417 Korean parents with elementary school children living in Seoul and Gyeonggi Province in the central area of Korea. The survey results revealed gaps between the knowledge or practices of Korean consumers and scientific evidence pertaining to safe food handling practices. Based on these findings, a leaflet on safe food handling guidelines was developed in accordance with Korean food culture. These guidelines suggest personal hygiene practices as well as fundamental principles and procedures for safe food handling from the stage of food purchase to that of keeping leftover dishes. A pilot application study with 50 consumers revealed that the guidelines effectively improved Korean consumers' safe food handling practices, suggesting that they can serve as practical educational material suitable for Korean consumers.

Variation in saltiness perception of soup with respect to soup serving temperature and consumer dietary habits.

Little is known about the effect of serving temperature on saltiness perception in food products such as soups that are typically consumed at high temperature. This study focused on determining whether serving temperature modulates saltiness perception in soup-base products. Eight trained panelists and 62 untrained consumers were asked to rate saltiness intensities in salt water, chicken broth, and miso soup, with serving temperatures of 40, 50, 60, 70, and 80 °C. Neither trained nor untrained panelists were able to find significant difference in the saltiness intensity among salt water samples served at these five different temperatures. However, untrained consumers (but not trained panelists) rated chicken broth and miso soup to be significantly less salty when served at 70 and/or 80 °C compared to when served at 40 to 60 °C. There was an interaction between temperature-related perceived saltiness and preference; for example, consumers who preferred soups served at lower temperatures found soups served at higher temperatures to be less salty. Consumers who frequently consumed hot dishes rated soup samples served at 60 °C as saltier than consumers who consumed hot dishes less frequently. This study demonstrates that soup serving temperature and consumer dietary habits are influential factors affecting saltiness perception of soup.

Changes in Eggshell Surface Microstructure after Washing with Cetylpyridinium Chloride or Trisodium Phosphate.

The effects of egg-washing chemicals on microstructural changes of the eggshell were examined. Fresh-laid eggs were washed with solutions of cetylpyridinium chloride (CPC) at 10, 50, or 100 ppm, or trisodium phosphate (TSP) at 0.5, 1.0, or 5.0% and changes in the shell surface were examined using scanning electron microscopy (SEM). As the concentration of CPC increased, the eggshell surface became pitted and the cuticle layer became thinner. TSP caused the cuticle layer to fissure and flake and even cuticle-free areas were observed at 5.0%. When the porosity of eggs was measured by using the blue lake staining method, there were significant differences between control and TSP- or CPC-washed eggs as observed by SEM. These results suggest that depending on the types of chemicals used in the wash water, different microstructural changes occur in eggshell surfaces, and the more damaged eggshell surfaces allow more bacterial penetration.

Morphological Changes of Salmonella typhimurium Caused by Electrical Stimulation in Various Salt Solutions.

To better understand what physical changes occur in bacteria subjected to low-voltage, low-current electrical stimulation (ES), morphological changes in Salmonella typhimurium killed by ES were examined using electron microscopy. Cells (107 CFU/ml) were suspended in 0.015 M NaCl, 0.015 M Na2CO3, or 0.005 M Na3PO4·12H2O solutions and pulsed electric signals at 10 mA/cm2 current, 1 kHz frequency and 50% duty cycle were applied until more than 90% of the cells were dead. In NaCl solutions, cells were swollen before collapsing into amorphous bodies. In Na2CO3 solutions, cells showed irregular surfaces and the cytoplasm became less dense at the centers of the cells. In Na3PO4 solutions, the cytoplasm was scattered into small aggregates within the cell and many fibrils were formed outside. The results of this research suggest that the mechanisms of destruction of S. typhimurium by ES depend on the salt used an electrolyte.

Reduction of Salmonella and Campylobacter on Chicken Carcasses by Changing Scalding Temperature.

Chickens were processed at three scalding temperatures, 52, 56, or 60°C, and the numbers of Salmonella and Campylobacter attached to the fully processed carcasses in each group were compared. For Salmonella , carcasses scalded at 52 or 56°C showed ~ 0.3 to 0.5 lower log numbers than carcasses at 60°C (P < 0.05). There were no significant differences between the carcasses at 52 and 56°C. For Campylobacter , carcasses scalded at 56°C showed ~ 0.7 lower log counts than the carcasses at 60°C (P < 0.05) in the first two trials; however, no difference was observed in a third trial. Although the reduction of bacteria attached to the chicken carcasses was not as great as shown in previous attachment studies using skin samples (1.0 to 1.4 log cycles), these results show that reductions in bacterial numbers on chicken carcasses can be achieved by simply changing the scalding temperature.

Effect of Trisodium Phosphate on Campylobacter Attached to Post-Chill Chicken Carcasses.

Trisodium phosphate (TSP) was evaluated as a means to reduce Campylobacter on chicken carcasses. Post-chill chicken carcasses were dipped into a 10% TSP solution at 50°C for 15 s. After storing the TSP-treated carcasses for 0, 1 or 6 days at 4°C, the carcasses were subjected to the recovery of Campylobacter . The incidence and reduction of Campylobacter attached to the carcasses were measured using a nitrocellulose (NC) membrane lift, conventional culture method, and a most probable number (MPN) technique. In trials 1 and 2, the incidence of Campylobacter was measured. For 1 day-stored groups, Campylobacter was present on 96 and 100% of control carcasses and present on 24 and 28% of TSP-treated carcasses as measured by NC membrane lift method. The reduction was less (4 to 36%) when measured by culture method. For carcasses immediately subjected for the recovery of cells after treatment, there was no difference between TSP-treated and control carcasses by either NC membrane or culture method. In trial 3, the reduction levels of Campylobacter were quantified by using a MPN method. The levels of Campylobacter on carcasses were decreased by 1.5 and 1.2 logs in 1- and 6-day stored, TSP-treated carcasses, respectively (p < 0.05). However, TSP treatment at 10°C reduced the level of Campylobacter only by 0.16 log (p > 0.10).

Attachment of Salmonella typhimurium to Skins of Turkey that had been Defeathered through Three Different Systems: Scanning Electron Microscopic Examination.

Attachment of Salmonella typhimurium to the skin of turkeys that had been processed through three different defeathering systems (conventional, kosher, and steam-spray) was examined at varying incubation times (10~60 min) using scanning electron microscopy. The extent of attachment varied with the type of defeathering method and increased with incubation time. Conventional and kosher skins showed slow rate of attachment, whereas steam-spray skin allowed a sharp increase of attachment, due to the collagenous connective tissue of dermis exposed during processing. Exposed dermis in kosher skin revealed the very adhesive properties of dermis. Attachment fibrils appeared as incubation time increased. Cells on steam-spray skin produced a considerable amount of long, thin fibrils connecting them to each other and to the skin after 30 min of incubation. While a few thick and short attachment fibrils were observed in conventional skin, no fibrils were detected in kosher skin. The high number of attached cells and the greatest amount of fibril formation on the surface of steam-spray skin suggest the positive relationship between bacterial attachment and fibril formation. Depressions produced by attached cells were observed in conventional skin surface, but not in kosher skin, probably due to the fatty and pliable properties of conventional skin. Pits, observed only on the surface of steam-spray skin, reflected the weak property of basal membrane covering the dermis. The above results suggest that exposing dermis is undesirable for reducing bacterial attachment during poultry processing.

Penetration of Salmonella typhimurium into Turkey Skin.

Penetration of Salmonella typhimurium into the turkey skins from three different defeathering systems (conventional, kosher, and steam-spray) was quantified by transverse sectioning of inoculated skins with a cryostat and fluorescent antibody staining of skin section homogenates. The microtopography of each skin observed by transmission electron microscopy was correlated with cell penetration. Although few cells were recovered due to freeze injury or freeze killing, direct plating of skin section homogenates showed the different properties of each skin for cell penetration. Fluorescent antibody staining recovered the most cells and revealed the cell distribution within the skin. In conventional skin, over 90% of cells resided in the upper 50 µm depth of skin, which implies the poor penetration of cells. Kosher skin showed relatively even distribution of cells up to 150 µm in depth, which indicated the penetration of cells even into the dermis. Steam-spray skin allowed the deepest (over 200 µm depth) and the highest number of penetration among the three types of skin. Conventional skin retained a thin layer of epidermis (0.3 ~ µm of stratum germinativum ) on the surface, and it appeared to act as an effective physical shield against bacterial invasion. The loss of all epidermis on steam-spray skin could explain the deep penetration following this process. Kosher skin retained the most epidermis; however, the characteristic lengthy picking time in kosher processing caused mechanical damage to the skin and allowed deep penetration of cells.

Influence of Three Defeathering Systems on Microtopography of Turkey Skin and Adhesion of Salmonella typhimurium.

The microtopography of turkey skin resulting from three different defeathering systems and consequent effect of skin microtopography on the adhesion of Salmonella typhimurium were examined. Turkeys from common flocks were scalded and picked using conventional, kosher, and steam-spray systems. Breast skin was subsequently removed, irradiated to eliminate the resident microflora, then inoculated with S. typhimurium for 30 min. Scanning electron microscopy (SEM) and light microscopy revealed that three processes caused different skin microtopographies, which resulted in different amounts of bacterial adhesion. Conventional skin had a comparatively smoother surface and less bacterial attachment. Kosher skin was very rough with a scaly keratinized epidermis and showed little bacterial attachment. Steam-spray skin had a highly convoluted surface (probably with underlying collagen fiber bundles) and showed three times higher attachment of cells than conventional and kosher skins. Contrary to counts of attached cells obtained by scanning electron microscopy, plate counts of all inoculated skins were similar and increased linearly with increasing inoculum concentration. The highest Sm value (an indirect measurement of attachment strength) of kosher skin reflected deep penetration/entrapment of cells within the skin rather than strong attachment of cells, whereas the high Sm value of steam-spray skin would reflect the strong attachment of cells to the specific receptors in the skin. The lowest Sm value and much bigger cell size of S. typhimurium on conventional skin reflected loose bacterial attachment and different surface properties, respectively.

Attachment of Salmonella typhimurium to Skins of Chicken Scalded at Various Temperatures.

Microtopography of chicken skin was studied by varying scalding temperature to determine the least favorable skin surface for salmonellae attachment. Birds were scalded at 52, 56, and 60°C, and the changes of skin morphology were examined by light and transmission electron microscopy throughout the whole processing. Breast skins obtained immediately after picking were inoculated with Salmonella typhimurium, and the attachment was quantified by using scanning electron microscopy and microbiological plating techniques. Skins scalded at 52 and 56°C retained most of the epidermis, although the latter temperature caused the loss of twice as much stratum corneum layers and produced a smoother surface than the former. Skins at 60°C began to lose most of epidermal layers during scalding and exposed dermal surface after picking, which was sometimes covered with thin fragmental epidermis or basal tissue. The number of salmonellae attached to 60°C-processed skins was 1.1~1.3 logs higher than those attached to the skins processed at 52 and 56°C, as measured by scanning electron microscopy. Microbiological plating, however, showed no significant difference in attachment among three skins processed at different temperatures. This was probably due to the insensitivity of the plating method to differentiate attachment strengths of salmonellae to the skin. The above results suggest that removal of whole epidermis should be avoided in processing to reduce salmonellae attachment to the skin.