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Biomedical subjects

E M Haymes

Publications and source records attributed to E M Haymes.

At least 37 records · Page 2Linked to original sources
PubMed1991

Acute effects of resistance exercise on parameters of lipoprotein metabolism.

Ten healthy, trained males (25.4 +/- 3.1 yr) were studied before and after 90 min of resistance exercise to determine the acute effects of high volume (HV) and low volume (LV) sessions on alterations in lipid and lipoprotein concentrations as well as the activity of lecithin: cholesterol acyltransferase (LCAT). The HV session involved the use of 8-12 repetition maximum (RM) loads performed to exhaustion with 60 s rest intervals between sets, while the LV session involved the use of 1-5RM loads with 3 min rest intervals between sets. Fasting blood samples were drawn from an antecubital vein immediately before and after exercise as well as 24, 48, and 72 h post-exercise. Following adjustment for changes in plasma volume, significant changes were only found following the HV session. These included increases in HDL-C (11%) and HDL3-C (12%) 24 h post-exercise. Modifications in HDL-C were significantly different from both the LV and control sessions. In contrast, triglycerides and LCAT were significantly depressed 24 h post-exercise following the HV session when compared with immediate post-exercise values. There were no significant changes in either total cholesterol or HDL2-C at any time. The results of this study suggest that the potential of resistance exercise to affect acute modifications in the lipoprotein profile resides in the volume of exercise performed.

Adult↗
PubMed1990

Metabolic effects of exposure to hypoxia plus cold at rest and during exercise in humans.

To determine effects on metabolic responses, subjects were exposed to four environmental conditions for 90 min at rest followed by 30 min of exercise: breathing room air with an ambient temperature of 25 degrees C (NN); breathing room air with an ambient temperature of 8 degrees C (NC); hypoxia (induced by breathing 12% O2 in N2) with a neutral temperature (HN); and hypoxia in the cold (HC). Hypoxia increased heart rate (HR), systolic blood pressure (SBP), pulmonary ventilation (VE), respiratory exchange ratio (R), blood lactate, and perceived exertion during exercise while depressing rectal temperature (Tre) and O2 uptake (VO2). Cold exposure elevated SBP, diastolic blood pressure (DBP), VE, VO2, blood glucose, and blood glycerol but decreased HR, Tre, and R. Shivering and DBP were higher and Tre was lower in HC compared with NC. HR, SBP, VE, R, and lactate tended to be higher in HC compared with NC, whereas VO2 and blood glycerol tended to be depressed. These results suggest that cold exposure during hypoxia results in an increased reliance on shivering for thermogenesis at rest whereas, during exercise, heat loss is accelerated.

Adult↗
PubMed1989

Effects of repeated short-term cold exposures on cold induced thermogenesis of women.

The effects of repeated exposures to resting cold air (10 degrees C) on the shivering and thermogenic responses of women to standard cold stress were investigated. Ten women, aged 18 to 34 years, were divided into two groups of five women each. One group, the acclimated (A) was exposed ten times within 2 weeks, the first and the last exposures being the pre- and post-tests, respectively. The second group, the control (C) was exposed twice within 18 days. Measurements of rectal and skin temperatures, oxygen uptake, time to onset of shivering (TOS), and perceived cold were performed during all exposures. Shivering responses were evaluated by electromyography and visually. A significant (P less than 0.05) increase was seen in TOS (from 26.2 min to 55.6 min), and a significant decrease was seen in thermoregulatory heat production (from 14.78 kcal/h to -2.64 kcal/h) in group A; these changes were evident after about five exposures. It is concluded that the women became cold acclimated as a result of the repeated short-term resting cold air exposures.

Acclimatization↗
PubMed1989

Iron status of women distance runners, sprinters, and control women.

Fasting blood samples from 11 women distance runners, 12 sprinters, and 11 moderately active women were examined to determine iron status. Dietary iron intake and bioavailability were analyzed from 3-day food diaries. Both distance runners and sprinters had lower hematocrits and haptoglobins than moderately active women. Distance runners had significantly lower ferritin (15.8 micrograms/l) than sprinters (32.8 micrograms/l), but moderately active women's ferritin (26.1 micrograms/l) was not significantly different than in the other groups. Five distance runners, two sprinters, and one moderately active woman had ferritins below 12 micrograms/l, which suggests iron depletion. Differences in hemoglobin, plasma iron, transferrin, and food iron intake were not significant among the three groups. Absorbable iron and heme iron intake were significantly lower for the distance runners and control women than the sprinters. The results suggest that low ferritin is more common among women who train for distance events than for sprints. This difference may by due to differences in bioavailability of food iron intake.

Adult↗
PubMed1988

Sweat iron loss of male and female runners during exercise.

Male (n = 9) and female (n = 8) collegiate cross-country runners were studied during a training session to determine the amount of iron lost in the sweat. Sweat samples were collected from the arm using polyethylene bags. Total sweat loss was determined by weighing subjects before and after the runs. Average time of sweat collection was 42 min for males and 39 min for females. Sweat rate for the males (717.5 +/- 145.9 g/m2/h) was significantly greater than for the females (460.1 +/- 142.9 g/m2/h); however, the sweat rate per km was not significantly different. Females had a significantly greater sweat iron concentration (0.417 +/- 0.024 mg/l) than males (0.179 +/- 0.011 mg/l). Rate of sweat iron loss was not significantly different for females (0.276 +/- 0.140 mg/h) and males (0.21 +/- 0.13 mg/h). Sweat iron concentration was inversely related with sweat rate (r = -0.64). Our data suggest that although males lose more total sweat than females, the higher sweat iron concentration of females leads to similar rates of iron loss. For female runners, sweat iron loss coupled with a low dietary iron intake may result in a negative iron balance.

Adolescent↗
PubMed1987

Nutritional concerns: need for iron.

Depletion of iron stores is frequently seen in male and female distance runners. Possible causes of this iron depletion include inadequate iron intake especially among females and increased iron excretion through sweating and gastrointestinal blood loss. Animal studies suggest that iron deficiency without anemia can reduce endurance by lowering tissue cytochromes and the activity of certain muscle tissue enzymes. Iron supplementation appears to be beneficial in reducing blood lactate concentrations following heavy exercise. The amount of iron in the supplement appears to influence the amount of increase in hemoglobin and serum ferritin.

Anemia, Hypochromic↗
PubMed1986

Training for cross-country skiing and iron status.

Effects of iron supplements and training for cross-country skiing on hematological and iron status were studied in nine men and ten women from the U. S. Nordic ski team. Four men and five women received a multiple vitamin, multiple mineral supplement containing 18 mg iron for 8 months while five men and five women received a placebo. Fasting blood samples were taken from all skiers prior to supplementation (May) and in August, November, and January. Hemoglobin, hematocrit, plasma iron, total iron binding capacity (TIBC), percentage of transferrin saturation, serum ferritin, free erythrocyte porphyrin, and haptoglobin were measured on each sample. Hemoglobin, hematocrit, and TIBC were higher in November when both men and women skiers trained at altitude than in August. In January TIBC was further increased, haptoglobin was increased, hemoglobin for the men fell below May levels, and hematocrit returned to May levels. Skiers receiving iron had lower TIBC levels in November and January than the placebo group. Six women and two men had ferritin levels below 28 ng X ml-1, which suggests prelatent iron deficiency. Free erythrocyte porphyrin levels above 100 micrograms X dl-1 RBC were found in all skiers at some point during training. The results suggest that multivitamin, multimineral supplements containing iron have little effect on the iron status of cross-country skiers.

Adolescent↗
PubMed1984

Coagulation and fibrinolytic responses to exercise and cold exposure.

This study examined the effect of acute cold exposure on coagulation (PTT) and fibrinolysis (ELT), and the effect of cooling on subsequent exercise-induced coagulation and fibrinolytic responses. Ten male volunteers were tested at 5 degrees C and 28 degrees C on alternate days. Each subject began by sitting quietly for 60 min. Each then exercised on a cycle ergometer at 50 W for 5 min followed by 150 W for 10 min. Venous blood samples were taken before rest, after rest, and after exercise for each temperature on each of the two days. PTT, ELT, and hematocrit (HCT) were determined at each interval. Rectal temperature (Tre) and mean skin temperature (Tsk) were assessed at 15-min intervals throughout. Tsk was stable under neutral conditions but declined rapidly in the cold environment. Tre response was more complex but was significantly different for one contrast only (CE less than NE). ELT was shortened to 74, 62, and 44% while HCT increased to 107, 107, and 111% of pretest values for CR, NE, and CE, respectively. No significant change was noted for PTT. It is concluded that acute cold exposure as well as exercise stress results in an increase in ELT activity of blood; simultaneous enhancement of the coagulation status of the blood in response to stress is not inextricably linked to an elevation of fibrinolytic activity, a result that questions the importance of the Hageman factor dependent pathway between coagulation and fibrinolysis.

Adult↗
PubMed1982

Effects of wind on the thermal and metabolic responses to exercise in the cold.

The thermal and metabolic responses to exercise were studied in a cold environment with and without a wind. Six men and two women rode a cycle ergometer for 90 min at 55-60% VO2max in a -20 degrees C environment. Subjects were exposed to a 4.1 m . s-1 wind on two of the four exposures. The subjects wore regulation cross-country ski uniforms. An additional vest was worn on 2 d, 1 d with the wind and 1 d without the wind. Total insulation for the ski uniform (Icl+a) was 1.59 clo and 1.77 clo with the vest. Final Tre, Tsk, and Tb were significantly lower, and radiative and convective heat loss, heat loss from body storage, and tissue insulation (It) were significantly greater when exercising in the wind. The addition of the vest increased only Tsk. Both metabolic rate and heart rate increased significantly during exercise, but no significant differences were observed between wind and no-wind conditions. The subjects responded to the increased cooling effect of the wind by increasing It, however, this response was not sufficient to prevent loss of stored heat and Tre from falling. It was concluded that the exercise intensity must be 10 METS or greater to maintain thermal balance when exercising in a -20 degrees C environment with a 4.1 m . s-1 wind if Icl+a = 1.59 clo.

Air Movements↗
PubMed1982

The effects of rest and exercise in the cold on substrate mobilization and utilization.

The effects of altering skin and core temperature by cold exposure and exercise on substrate mobilization and utilization were examined. Six subjects between the ages of 22-27 years rested and exercised in neutral and cold environments to produce 1) a neutral core and neutral skin temperature, 2) a neutral core and cold skin temperature, and 3) a cold core and cold skin temperature. Free fatty acid (FFA), glucose (GL), Lactate (LA), hemoglobin (Hb), and hematocrit (Hct) concentrations were measured along with heart rate (HR), respiratory exchange ratio (R) and oxygen consumption (VO2) after 30, 60, and 90 min of exposure to each condition. FFA, GL, LA, Hb, and Hct concentrations increased significantly during rest when both mean skin temperature (Tsk) and rectal temperature (Tre) were reduced. Plasma FFA concentration was also significantly elevated and R values were reduced during exercise when both Tsk and Tre were lowered compared to exercise in a neutral environment. No significant differences in substrate concentration, hemoconcentration, or R values were observed when Tsk alone was reduced at rest or during exercise. It is concluded that a preferential utilization of fat occurs during exercise in the cold when both Tsk and Tre are reduced compared to exercise in a neutral environment.

Adult↗
PubMed1980

Characteristics of elite male and female ski racers.

Fifty-four members of the U.S. Ski Team who competed in the alpine, cross-country, or Nordic combined events were studied to learn more about the characteristics of elite ski racers in each of the events. Variables examined were percent body fatness, maximal oxygen uptake, maximal ventilation, isometric knee extension strength, power, agility, balance, and response time. In addition, isokinetic knee extension strength and endurance were measured on the alpine skiers. Cross-country skiers had higher Vo2max adjusted for weight or lean body weight than alpine skiers of the same sex. Male skiers had larger VO2max with or without adjustments for weight or lean body weight than female skiers in the same events. Alpine skiers had significantly more isometric knee extension strength (males = 3078 N, females = 2194 N) and power during the Margaria-Kalamen stair run (males = 1791 W, females = 1131 W) than cross-country skiers of the same sex. Differences in isokinetic knee extension strength at slow rates of contraction (30 degrees/s) between male and female alpine skiers were not significant when strength was expressed as strength x kg LBW-1. Male alpine skiers produced more power and had more isokinetic leg strength x kg LBW-1 at high contraction rates (180 degrees/s) than female alpine skiers.

Adipose Tissue↗
PubMed1976

Validity of the ultrasonic technique as a method of measuring subcutaneous adipose tissue.

Subcutaneous adipose tissue measurements, at abdomen, suprailiac, subscapular, and mid-triceps sites, made with the ultrasonic and skinfold caliper techniques were compared using data from 20 women and 17 men from a pool of subjects of 22 women and 20 men. In addition, comparisons were made between ultrasonic, soft-tissue roentgenographic and skinfold caliper techniques at the suprailiac and mid-triceps sites on 6 women and 12 men. Repeat measurements with the ultrasonic technique produced correlation coefficients of 0-87 and above. Correlations between skinfold caliper and ultrasonic measurements were generally higher among women than men over each of the four sites. A highly significant relationship, r = 0-88, was observed between the ultrasonic measurements and soft-tissue roentgenograms over the mid-triceps site. The correlation between the fat-muscle interface measured on the roentgenogram and ultrasonic measurements at the suprailiac site was 0-78. Multiple echoes and interfaces were observed at the suprailiac site on some subjects.

Abdomen↗
PubMed1975

Heat tolerance of exercising lean and obese prepubertal boys.

Seven lean and five obese boys, aged 9-12 yr, exercised in four environments: 21.1, 26.7, 29.4, and 32.2 degrees C Teff. Subjects walked on a treadmill at 4.8 km/h, 5% grade for three 20-min exercise bouts separated by 5-min rest periods. Rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), sweat rate, and oxygen uptake (VO2) were measured periodically throughout the session. Lean boys had lower Tre and HR than obese boys in each of the environments. Increases in Tre were significantly greater for the obese at 26.7 and 29.4 degrees C Teff. No significant differences in Tsk and sweat rate (g-m-2-h-1) were observed between lean and obese boys. Obese boys had significantly lower oxygen consumptions per kg but worked at a significantly higher percentage of VO2max than lean boys when performing submaximal work. Responses of the obese boys to exercise in the heat were similar to those of heavy prepubertal girls studied previously, except that the boys were more tolerant of exercise at 32.2 degrees C Teff than the girls. Lean boys had lower HR than lean girls in each environment, but lower Tre only at 32.2 degrees C Teff.

Adult↗