Thermal insulation and body temperature wearing a thermal swimsuit during water immersion

This study evaluated the effects of a thermal swimsuit on body temperatures, thermoregulatory responses and thermal insulation during 60 min water immersion at rest. Ten healthy male subjects wearing either thermal swimsuits or normal swimsuits were immersed in water (26 degrees C or 29 degrees C). Esophageal temperature, skin temperatures and oxygen consumption were measured during the experiments. Metabolic heat production was calculated from oxygen consumption. Heat loss from skin to the water was calculated from the metabolic heat production and the change in mean body temperature during water immersion. Total insulation and tissue insulation were estimated by dividing the temperature difference between the esophagus and the water or the esophagus and the skin with heat loss from the skin. Esophageal temperature with a thermal swimsuit was higher than that with a normal swimsuit at the end of immersion in both water temperature conditions (p<0.05). Oxygen consumption, metabolic heat production and heat loss from the skin were less with the thermal swimsuit than with a normal swimsuit in both water temperatures (p<0.05). Total insulation with the thermal swimsuit was higher than that with a normal swimsuit due to insulation of the suit at both water temperatures (p<0.05). Tissue insulation was similar in all four conditions, but significantly higher with the thermal swimsuit in both water temperature conditions (p<0.05), perhaps due to of the attenuation of shivering during immersion with a thermal swimsuit. A thermal swimsuit can increase total insulation and reduce heat loss from the skin. Therefore, subjects with thermal swimsuits can maintain higher body temperatures than with a normal swimsuit and reduce shivering thermo-genesis.     

Effect of pressure on thermal insulation in humans wearing wet suits

The present work was undertaken to determine the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 3 h without shivering, of wet-suited subjects during water immersion at different ambient pressures. Nine healthy males wearing neoprene wet suits (5 mm thick) were subjected to immersion to the neck in water at 1, 2, and 2.5 ATA while resting for 3 h. Continuous measurements of esophageal (T(es)) and skin (Tsk) temperatures and heat loss from the skin (Htissue) and wet suits (Hsuit) were recorded. Insulation of the tissue (Itissue), wet suits (Isuit), and overall total (Itotal) were calculated from the temperature gradient and the heat loss. The Tcw increased curvilinearly as the pressure increased, whereas the metabolic heat production during rest and immersion was identical over the range of pressure tested. During the 3rd h of immersion, Tes was identical under all atmospheric pressures; however, Tsk was significantly higher (P less than 0.05) at 2 and 2.5 ATA compared with 1 ATA. A 42 (P less than 0.001) and 50% (P less than 0.001), reduction in Isuit from the 1 ATA value was detected at 2 and 2.5 ATA, respectively. However, overall mean Itissue was maximal and independent of the pressure during immersion at Tcw. The Itotal was also significantly smaller in 2 and 2.5 ATA compared with 1 ATA. The Itissue provided most insulation in the extremities, such as the hand and foot, and the contribution of Isuit in these body parts was relatively small. On the other hand, Itissue of the trunk areas, such as the chest, back, and thigh, was not high compared with the extremities, and Isuit played a major role in the protection of heat drain from these body parts.     

Changes in thermal insulation during underwater exercise in Korean female wet-suit divers

The present work was undertaken to examine the effect of wet suits on the pattern of heat exchange during immersion in cold water. Four Korean women divers wearing wet suits were immersed to the neck in water of critical temperature (Tcw) while resting for 3 h or exercising (2-3 met on a bicycle ergometer) for 2 h. During immersion both rectal (Tre) and skin temperatures and O2 consumption (VO2) were measured, from which heat production (M = 4.83 VO2), skin heat loss (Hsk = 0.92 M +/- heat store change based on delta Tre), and thermal insulation were calculated. The average Tcw of the subjects with wet suits was 16.5 +/- 1.2 degrees C (SE), which was 12.3 degrees C lower than that of the same subjects with swim suits (28.8 +/- 0.4 degrees C). During the 3rd h of immersion, Tre and mean skin temperatures (Tsk) averaged 37.3 +/- 0.1 and 28.0 +/- 0.5 degrees C, and skin heat loss per unit surface area 42.3 +/- 2.66 kcal X m-2 X h. The calculated body insulation [Ibody = Tre - Tsk/Hsk] and the total shell insulation [Itotal = (Tre - TW)/Hsk] were 0.23 +/- 0.02 and 0.5 +/- 0.04 degrees C X kcal-1 X m2 X h, respectively. During immersion exercise, both Itotal and Ibody declined exponentially as the exercise intensity increased. Surprisingly, the insulation due to wet suit (Isuit = Itotal - Ibody) also decreased with exercise intensity, from 0.28 degrees C X kcal-1 X m2 X h at rest to 0.12 degrees C X kcal-1 X m2 X h at exercise levels of 2-3 met.(ABSTRACT TRUNCATED AT 250 WORDS)     

Critical water temperature during water immersion at various atmospheric pressures

The present work was undertaken to determine the effect of atmospheric pressure [ranging from a high altitude of 4,300 m above sea level or 0.6 atmospheres absolute (ATA) to depths of 10 m deep or 2 ATA] on the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 2 h without shivering, of the unprotected subject during water immersion. Nine healthy males wearing only shorts were subjected to immersion to the neck in water at 0.6, 1, and 2 ATA while resting for 2 h. Continuous measurements included esophageal (Tes) and skin (Tsk) temperatures, direct heat loss from the skin (Htissue), and insulation of the tissue (Itissue). The Tcw was significantly higher at 0.6 ATA than 1 and 2 ATA: however, Tcw at 1 ATA was identical to that at 2 ATA. The metabolic heat production remained unchanged among the pressures. During the 2-h immersion in Tcw, Tes was identical among all atmospheric pressures: however, Tsk was significantly higher (P less than 0.05) at 0.6 ATA and was identical between 1 and 2 ATA. The overall mean Itissue was near maximal during immersion in Tcw in each pressure, and no difference was detected among the pressures. However, Itissue at the acral extremities (arm, hand, and foot) decreased significantly at 0.6 ATA, and subsequently heat loss from these parts was increased, which elevated an extremity-to-trunk heat loss ratio to 1.4 at 0.6 ATA from 1.1 at 1 and 2 ATA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic and vasomotor insulative responses occurring on immersion in cold water

Twenty male volunteers (17-28 yr of age) exhibiting a range of body weights (60 kg less than or equal to Wt less than or equal to 95 kg) and body fat (7% less than or equal to BF less than or equal to 23%) underwent total immersion while at rest in water between 36 and 20 degrees C. The metabolic heat production measured as a function of time and water temperature was converted to explicit linear functions of core (Tre) and mean skin (Tsk) temperature for each individual immersion. The metabolic functions defined planes of thermogenic activity that showed a fourfold steeper slope with respect to changes in Tsk for small lean subjects than for large fatter subjects. Small lean males also exhibited steeper slopes with respect to changes in Tre than heavier phenotypes. The time course of Tsk and Tre was simulated for each individual immersion with the aid of a time-dependent system of differential heat balance equations coupling different body compartments to the water bath. This formulation permitted the evaluation of internal and external conductances as a function of water temperature. Maximal internal insulation, indicating full vasoconstriction, was achieved at higher bath temperatures in small lean subjects than large fatter subjects. A decline in insulation is seen above a critical metabolic level (approximately 150 W) in small to average size subjects.     

Thermoregulatory and subjective responses of clothed men in the cold during continuous and intermittent exercise

Thermoregulatory and thermal subjective responses were studied in ten male, clothed subjects during continuous (C) and intermittent (I) exercise at the same average level of oxygen consumption. The subjects performed both I and C twice, dressed in two different three-layer cold-protective clothing ensembles of two thermal insulation levels [total clothing insulation = 2.59 clo (L) and 3.20 clo (H)]. Experiments were carried out at an ambient temperature of -10 degrees C. Rectal temperatures increased similarly in both types of exercise. Mean skin temperature (Tsk) was lower in I compared to C with both levels of clothing insulation. Over the last 0.5 h of the experiment Tsk was approximately 1.3 degrees C lower in I than in C for clothing L. The skin evaporation rate was higher in clothing H than L but did not differ between I and C. Subjective ratings for thermal sensations of the whole body (BTS) and hands were close to neutral in I and around slightly warm in C. The BTS was lower in I than in C and was lower in L compared to H. It was concluded that, at equal average energy expenditure, thermal responses to intermittent and continuous exercise in the cold differ in clothed subjects, principally as a result of different patterns of heat exchange.     

Water temperature and intensity of exercise in maintenance of thermal equilibrium

This study examined the thermal and metabolic responses of six men during exercise in water at critical temperature (Tcw, 31.2 +/- 0.5 degrees C), below Tcw (BTcw, 28.8 +/- 0.6 degrees C), at thermoneutrality (Ttn, 34 degrees C), and above Ttn (ATtn, 36 degrees C). At each water temperature (Tw) male volunteers wearing only swimming trunks completed four 1-h experiments while immersed up to the neck. During one experiment, subjects remained at rest (R), and the other three performed leg exercise (LE) at three different intensities (LE-1, 2 MET; LE-2, 3 MET; LE-3, 4 MET). In water warmer than Tcw, there was no difference in metabolic rate (M) during R. The M for each work load was independent of Tw. Esophageal temperature (Tes) remained unchanged during R in water of ATtn (36 degrees C). However, Tes significantly (P less than 0.05) declined over 1 h during R at Ttn (delta Tes = -0.39 degrees C), Tcw (delta Tes = -0.54 degrees C), and BTcw (delta Tes = -0.61 degrees C). All levels of underwater exercise elevated Tes and M compared with R at all Tw. In water colder than Tcw, the ratio of heat loss from limbs compared with the trunk became greater as LE intensity increased, indicating a preferential increase in heat loss from the limbs in cool water. Tissue insulation (Itissue) was lower during LE than at R and was inversely proportional to the increase in LE intensity. A linearly inverse relationship was established between Tw and M in maintaining thermal equilibrium.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of uniform and non-uniform skin temperature on thermal exchanges in water in humans

We investigated the effect of uniform (UST) and non-uniform (NUST) skin temperature on thermal exchanges during a 3-h water immersion in five male subjects wearing (NUST) or not wearing (UST) a water-perfused garment. UST was achieved by immersing the nude subject in water up to the neck. For each subject, the water temperature was adjusted to the critical temperature ( T(cw), 31.4 +/- 0.9 degrees C) or 3 degrees C below T(cw) ( T(cw) - 3). NUST was achieved by perfusing different segments of the perfused garment with water of different temperatures. The water temperature of the segment was independently adjusted according to the skin temperature distribution in cold air, the mean skin temperature being the same as the UST. At T(cw) and T(cw) - 3, changes in esophageal and mean skin temperatures were identical in UST and NUST conditions, but the skin temperature of the trunk was higher and that of the limb was lower in the NUST condition. Heat production and the overall skin heat flux at T(cw) were identical in the two conditions, but those at T(cw) - 3 were about 25% lower ( P < 0.05) in NUST than in UST conditions. At T(cw) - 3, the overall tissue insulation was 36% higher ( P < 0.05) in NUST than in UST conditions, mainly because of higher limb insulation. Thermogenesis due to shivering was lower by 62% ( P < 0.05) in NUST than in UST. We conclude that the NUST condition increased tissue insulation and suppressed shivering. This suggests that a high skin temperature of the trunk attenuates shivering in cold water and increases the ability to defend body temperature more economically in cold water.     

Changes in insulation of body tissue and wet suits during underwater exercise at various atmospheric pressures

To clarify the independent changes of insulations of body tissues (Itissue) and wet suit (Isuit) in the wet-suited subject during underwater exercise, overall heat flow from the skin (Htissue) and wet suit (Hsuit) and esophageal (Tes), skin (Tsk), and wet suit temperatures were measured at 1, 2, and 2.5 atmospheres absolute (ATA) at critical water temperature (Tcw). The average Tcw in nine wet-suited men (23-38 yr) was 22.3 +/- 0.2, 26.3 +/- 0.2, and 28.0 +/- 0.4 degrees C (SE) at 1, 2, and 2.5 ATA, respectively. At Tcw of each pressure male volunteers wearing 5-mm neoprene wet suits completed three 2-h experiments while immersed up to the neck. During one experiment the subjects remained at rest, and in the other two they exercised on an underwater ergometer at two different intensities (2 and 3 met). Tes significantly declined (P less than 0.05) over 2 h from 37.1 to 36.5 degrees C during rest in each pressure. The 2-met exercise prevented Tes from falling in all pressures, and the 3-met exercise elevated Tes by 0.2-0.3 degrees C. There was no exercise-dependent difference in Isuit, but a pressure-dependent difference was remarkable. The Itissue at rest was identical for all pressures; however, it progressively decreased as a function of exercise intensity. It is concluded that overall Itissue is entirely determined by work intensity at Tcw, but not by atmospheric pressure. On the contrary, Isuit at Tcw is solely dependent on the pressure, but not on the work intensity.     

Seasonal variations of physiological characteristics and thermal sensation under identical thermal conditions

Seasonal variations of human thermal characteristics were inspected in thermal comfort and when constantly indoors. Metabolic rate, tympanic temperature, skin temperature, body fat, body weight and thermal sensation were measured under identical thermal conditions in a chamber over the course of one year. Experiments were carried out for each subject in both summer and winter. Six subjects were measured 35 times in summer and 45 times in winter. one subject was measured weekly for 14 months. Measurements for analyses were taken 40-60 min after entrance into the chamber. Results revealed the following. 1) For all subjects, the metabolic rate, tympanic temperature and body fat were lower in summer than in winter; thigh skin temperatures were higher in summer than in winter. The averaged individual ratio of seasonal difference was 11.9% for metabolic rate, 14.9% for body fat, 1.8% for thigh temperature and 0.53% for tympanic temperature. Seasonal differences of about 10% in metabolic rate were maintained in this study. 2) Seasonal variations of the variables were examined for phase relationships against the outdoor temperature. 2-1) Metabolic rate, thermal sensation, body weight and body fat changed in reverse phase, whereas skin temperature was in-phase. 2-2) Skin temperature lagged by about one month in both summer and winter. Body fat also lagged by about one month in summer, but corresponded to the phase in winter. Metabolic rates were also in-phase in winter but led about three months in summer. Thermal sensations lagged by about three months in winter but were in-phase in summer. Body weight was in-phase in summer and winter. 2-3) Summer disorders were observed particularly in seasonal variations of metabolic rates, tympanic temperature, skin temperatures, and thermal sensation, thereby suggesting that the effect of temperature exposure was altered by air-conditioner use.     

Fat, Energy and Mammalian Survival

Adipose tissue plays a critical role in mammalian life historystrategies, serving as an organ for the storage of food andenergy, as a source of heat and water and as thermal insulation.The food and energy storage roles are especially important inallowing the animals to survive food shortages and stressesassociated with competition for mates, territorial defense,gestation and lactation, and to accomplish migrations. The composition,cellularity and anatomical site of adipose depots in a mammalcan influence both the amount of fat stored and its availabilityand usefulness in any given situation. The fatty acids and complexlipids in adipose tissue, blood vessels, nerves and brain changein response to ambient temperature and the low body temperaturesduring hibernation. Early nutrition may influence the numberof fat cells developed by a mammal, and thus affect its abilityto survive adversity. Desert species develop localized depotswhich will not interfere with temperature regulation, whileanimals in cold environments use their extensive superficialfat layers as insulation.     

Influence of skeletal muscle glycogen on passive rewarming after hypothermia

To examine the influence of muscle glycogen on the thermal responses to passive rewarming subsequent to mild hypothermia, eight subjects completed two cold-water immersions (18 degrees C), followed by 75 min of passive rewarming (24 degrees C air, resting in blanket). The experiments followed several days of different exercise-diet regimens eliciting either low (LMG; 141.0 +/- 10.5 mmol.kg.dry wt-1) or normal (NMG; 526.2 +/- 44.2 mmol.kg.dry wt-1) prewarming muscle glycogen levels. Cold-water immersion was performed for 180 min or to a rectal temperature (Tre) of 35.5 degrees C. In four subjects (group A, body fat = 20 +/- 1%), postimmersion Tre was similar to preimmersion Tre for both trials (36.73 +/- 0.18 vs. 37.26 +/- 0.18 degrees C, respectively). Passive rewarming in group A resulted in an increase in Tre of only 0.13 +/- 0.08 degrees C. Conversely, initial rewarming Tre for the other four subjects (group B, body fat = 12 +/- 1%) averaged 35.50 +/- 0.05 degrees C for both trials. Rewarming increased Tre similarly in group B during both LMG (0.76 +/- 0.25 degrees C) and NMG (0.89 +/- 0.13 degrees C). Afterdrop responses, evident only in those individuals whose body core cooled during immersion (group B), were not different between LMG and NMG. These data support the contention that Tre responses during passive rewarming are related to body insulation. Furthermore these results indicate that low muscle glycogen levels do not impair rewarming time nor alter after-drop responses during passive rewarming after mild-to-moderate hypothermia.     

Insulative power of body fat on deep muscle temperatures and isometric endurance.

Four male subjects were examined to assess the relationship of body fat content to deep muscle temperature and the endurance of a fatiguing isometric handgrip contraction at a tension set at 40% MVC. Muscle temperature was altered by the immersion of the forearm in water at temperatures varying from 7.5 to 40 degrees C. In all subjects, there was a water bath temperature above and below which isometric endurance decreased markedly; the difference among individuals was solely accounted for by the individual's body fat content. Thus, subjects with higher body fat content required lower bath temperatures to cool the forearm musculature to its optimum temperature, which we found to always be approximately 27 degrees C measured 2 cm perpendicularly to the skin in the belly of the brachioradialis muscle. Further, in one subject, we found that a reduction in this subject's body fat content resulted in a corresponding increase in the water bath temperature necessary to cool his muscles to their optimum isometric performance. The data demonstrate the striking insulative power of the thin layer of fat around the forearm in man in protecting shell tissues from cold exposure.     

Thermal adjustment to cold-water exposure in exercising men and women

Thermoregulatory responses were studied in 10 men and 8 women during 36-W exercise for 1 h in air and water at 20, 24, and 28 degrees C. Men were classified as high (27.6%; n = 2), average (16.8%; n = 4), and low (9.2%; n = 4) percent body fat, whereas women were classified as average (25.2%; n = 4) and low (18.5%; n = 4) fat. For both men and women, exercise of about 1.7 l O2 X min-1 was beneficial in either preventing or retarding the fall in rectal temperature (Tre) observed in a previous study for the same subjects at rest. The greatest thermal strain was noted for the leanest subjects. However, in no instance did exercise facilitate a drop in Tre compared with resting conditions. Despite a larger surface area-to-mass ratio (P less than 0.05) and less effective thermoregulation for women at rest compared with men, essentially similar thermoregulatory responses were observed for both sexes during exercise at each water temperature. For both the men and women, the thermoregulatory benefits of exercise were due largely to the added heat production from physical activity. For the female, an additional benefit of exercise may in part be derived from a more favorable distribution of subcutaneous fat over the active musculature.     

不同保温措施对患儿全身麻醉后体温的影响

目的:探讨不同保温措施对患儿全身麻醉后体温的影响,以选择最佳的保温措施。方法:选择2016年1月-2017年6月我院300例择期需要手术的患儿,按照随机数字表法分为对照组(n=60)和实验组(n=240),实验组根据不同的保温措施分为输液输血加温组(A组)、身体包裹组(B组)、冲洗液加温组(C组)、加热毯组(D组),每组60例。所有患者术中均常规加盖棉被,室温控制在24~26℃,对照组不再采取另外的保温措施。观察并记录各组患儿在入室不同时间的鼻咽温和肛温。结果:A、C组鼻咽温和肛温随着时间的推移逐步下降,且入室90 min后较入室时明显降低,差异均有统计学意义(均P0.05);B组在入室后鼻咽温和肛温维持在比较稳定的水平(均P0.05);D组鼻咽温和肛温随着时间的推移逐步上升,在入室90 min后较入室时显著升高,差异具有统计学意义(均P0.05)。结论:首选加热毯保温能够维持全身麻醉的患儿体温正常,提高麻醉后的安全性,其次选身体包裹保温,必要时可联合应用多种保温措施。     

Physical fitness differences between prepubescent boys and girls

The purpose of this study was to analyze in which physical capabilities boys and girls are closer or distant. An additional objective was to find which of the body fat, physical activity, and somatotype factors have a greater effect on prepubescent children's physical fitness. This was a cross-sectional study involving 312 children (10.8 ± 0.4 years). The physical fitness assessment employed sets of aerobic fitness, strength, flexibility, speed, agility, and balance. The boys presented higher values in all selected tests, except tests of balance and flexibility, in which girls scored better. Gender differences in the physical fitness were greatest in the explosive strength of upper (p ≤ 0.01, η(p)(2) = 0.09) and lower limbs (p ≤ 0.01, η(p)(2) = 0.08), although with a medium-size effect of gender, and smaller in the abdominal (p > 0.05, η(p)(2) = 0.007) and upper limbs (p > 0.05, η(p)(2) = 0.003) muscular endurance, and trunk extensor strength and flexibility (p > 0.05, η(p)(2) = 0.001). The endomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the girls, and the ectomorphic (p ≤ 0.01, η(p)(2) = 0.31) and mesomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the boys, had the high-sized effect on the physical fitness. The physical activity in the girls, and the endomorphic and body fat in the boys, did not have a significant effect. These findings can help in the planning of activities that take into account the success and motivation of both boys and girls and thus increase levels of physical activity and physical fitness at school. However, in prepubescent children, one cannot neglect the influence of genetic determinism, observed from the morphoconstitutional point of view.     

Effects of body mass and morphology on thermal responses in water

Ten male volunteers were divided into two groups based on body morphology and mass. The large-body mass (LM) group (n = 5) was 16.3 kg heavier and 0.22 cm2 X kg-1 X 10(-2) smaller in surface area-to-mass ratio (AD X wt-1) (P less than 0.05) than the small-body mass (SM) group (n = 5). Both groups were similar in total body fat and skinfold thicknesses (P greater than 0.05). All individuals were immersed for 1 h in stirred water at 26 degrees C during both rest and one intensity of exercise (metabolic rate approximately 550 W). During resting exposures metabolic rate (M) and rectal temperature (Tre) were not different (P greater than 0.05) between the LM and SM groups at min 60. Esophageal temperature (Tes) was higher (P less than 0.05) for the SM group at min 60, although the change in Tes during the 60 min between groups was similar (LM, -0.4 degrees C; SM, -0.2 degrees C). Tissue insulation (I) was lower (P less than 0.05) for SM (0.061 degrees C X m-2 X W-1) compared with the LM group (0.098 degrees C X m-2 X W-1). During exercise M, Tre, Tes, and I were not different (P greater than 0.05) between groups at min 60. These data illustrate that a greater body mass between individuals increases the overall tissue insulation during rest, most likely as a result of a greater volume of muscle tissue to provide insulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Body fat and racial genetic admixture are associated with aerobic fitness levels in a multiethnic pediatric population

Aerobic fitness and adiposity are each independently associated with health outcomes among children, although the relationship between these two variables is unclear. Our objectives were to evaluate (i) the association of adiposity with aerobic fitness using objectively measured levels of percent body fat, compared to BMI as a percentile proxy for adiposity while controlling for genetic admixture, and (ii) the congruence of BMI categories with high and low body fat categories of objectively measured percent body fat. Participants were 232 African-American (AA), European-American (EA), and Hispanic-American (HA) children aged 7-12 years (Tanner stage <3). Aerobic fitness was measured via a submaximal indirect calorimetry treadmill test (VO(2-170)), and physical activity levels with accelerometry. Genetic admixture estimates were obtained using 140 genetic ancestry informative markers to estimate European, African, and Amerindian admixture. Fat mass was determined using dual-energy x-ray absorptiometry (DXA). Children were classified into a low body fat group (<25% in males, <30% in females) or a high body fat group based on their percent body fat; children were also categorized according to BMI percentile. Children in the low body fat group had significantly higher aerobic fitness (P < 0.05) regardless of BMI percentile classification. Higher African genetic admixture was associated with lower aerobic fitness (P < 0.05), while physical activity was positively associated with fitness (P < 0.01). In conclusion, aerobic fitness levels differ by percent body fat and genetic admixture irrespective of BMI classification, and such differences should be taken into account when evaluating outcomes of health interventions.     

Plasma lipids in Turkish children: impact of puberty, socioeconomic status, and nutrition on plasma cholesterol and HDL.

In Turkish adults, HDL cholesterol (HDL-C) levels are 10-15 mg/dl lower than those of adults in western Europe and the United States. In this study, we determined whether HDL-C levels in Turks are low from birth to adulthood and assessed the effect of socioeconomic status (SES) on plasma lipids and lipoproteins. Analyses of cord blood from 105 Turkish newborns showed low levels of plasma cholesterol ( approximately 60 mg/dl) and HDL-C (approximately 30 mg/dl), consistent with results from other Western ethnic groups. Prepubescent 8- to 10-year-old Turkish boys and girls of upper (n = 82) and lower (n = 143) SES had high HDL-C levels (50-60 mg/dl) similar to those of western European children. However, the cholesterol (154-158 mg/dl) and HDL-C (55-58 mg/dl) levels of upper SES children were approximately 25 and approximately 12 mg/dl higher, respectively, than those of lower SES children. Height, weight, skinfold thickness, and estimated body fat were greater in the upper SES children and appeared to reflect dietary differences. Upper SES children consumed more total fat (approximately 35% vs. 25% of total calories), including more saturated fat of animal origin, and less carbohydrate (approximately 50% vs. 62% of total calories), consistent with their elevated plasma cholesterol levels. Carbohydrate intake correlated inversely with the HDL-C level. The HDL-C levels in the prepubescent children, especially those of higher SES, who consumed diets more like western Europeans, decreased markedly to adult levels, with males exhibiting a approximately 20 mg/dl decrease (from 58 to 37 mg/dl) and females a approximately 13 mg/dl decrease (from 55 to 42 mg/dl). SES did not affect HDL-C levels in adults. The profound decrease may reflect alterations in androgen/estrogen balance in Turks at puberty and a modulation of hepatic lipase affecting HDL-C levels.     

Effects of basketball training on maximal oxygen uptake, muscle strength, and joint mobility in young basketball players

The purpose of this study was to examine the effects of prolonged basketball skills training on maximal aerobic power, isokinetic strength, joint mobility, and body fat percentage, in young basketball players, and controls of the same age. Twenty basketball players and 18 control boys participated in the study. Basketball players participated both in their school's physical education program and in a children's basketball team training program. Controls participated only in their school's physical education program. All subjects were tested every 6 months (18 months total, 11(1/2), 12, 12(1/2), 13 years old) for VO(2)max, peak torque values of the quadriceps and hamstrings at 180 and 300 degrees x s(-1) and range of motion of the knee and hip joints. Body fat percentage was assessed at the beginning and the end of the experimental period. Results showed that the basketball group had lower heart rate values in all ages and higher VO(2) values in the initial test compared with the control in submaximal intensity. The VO(2)max was altered in both groups on the final test, when compared to the initial test. However, the basketball group had a higher VO(2)max on each of the 6-month follow-up measurements, compared to the control group (p < 0.001). At the end of the 18-month follow-up period no significant differences were observed in isokinetic strength and joint mobility of the lower limbs between the 2 groups. On the contrary, the boys of the trained group had significantly lower percentage body fat values, compared to controls. In conclusion, regular basketball training increased aerobic power and decreased body fat percentage of prepubescent boys, while it did not affect muscle strength and joint mobility of the lower limbs. The major implication suggested by the findings of the present study is that, in order to improve the basic physical components, specific training procedures should be incorporated during the basketball training sessions. It is recommended that all children should be involved in some type of cardiovascular and resistance training program.