Relationship between personality type and achievement in an undergraduate physiology course.

The Myers-Briggs type indicator (MBTI) was given to 163 students in an undergraduate Human Physiology course at a large state university. Selected MBTI personality types were compared for achievement in the course using a t test to compare total points earned. High grades were earned by students stronger in the traits of introversion (I) and judgment (J), whereas the extraverted (E) and perceptive (P) types had the lowest grades and dropped out of the course in the largest numbers. When combinations of MBTI types were compared, the highest grades were earned as follows: SJ greater than ST greater than IN greater than IJ greater than IS (S, sensing; T, thinking; N, intuitive). This ranking indicates that a sensing personality also has a strong relationship to achievement in this Human Physiology course when it is combined with judgment, thinking, or introversion. Instructors and students need to be aware of the relationship between personality and learning so they can modify their teaching style and learning behavior to enhance academic achievement.

The effect of exercise at various temperatures on salivary levels of immunoglobulin A.

The purpose of this investigation was to determine the effect of ambient temperature on the salivary immunoglobulin A (s-IgA) response to submaximal exercise. Nine adult males (x age +/- SD = 22 +/- 2 yrs) volunteered to perform an incremental treadmill test to exhaustion for the determination of VO2max and three 30-minute treadmill runs at 80% VO2max in an environmental chamber at temperatures of approximately 6, 19 and 34 degrees C. Saliva samples were collected prior to each submaximal workbout as well as immediately and 1 hr post-exercise. A 2 within subjects factors (temperature, sample time) repeated measures ANOVA indicated no significant interaction or main effects for sampling time or temperature. The results of this study indicated that 30 minutes of non-competitive exercise at temperatures ranging from 6 to 34 degrees C had no effect on s-IgA. These findings suggest that moderate intensity exercises at a wide range of ambient temperatures does not increase the susceptibility to upper respiratory infection by decreasing s-IgA.

Mitogenic response of T-lymphocytes to exercise training and stress.

The impact of exercise training and stress on the immune response was examined by measuring the mitogenic response of spleen lymphocytes to the T-cell mitogen concanavalin A (Con-A). Male Sprague-Dawley rats were divided into four groups: sedentary controls (n = 11), handled controls (n = 12), treadmill runners (n = 10), and voluntary runners (n = 11) housed in running wheels. The treadmill group ran at 22 m/min (0.8 mph) for 45 min, 5 days/wk for 8 wk. After the training period, spleen lymphocytes isolated from each rat were incubated with Con-A for 54 h, pulsed with radiolabeled thymidine for 18 h, and counted for tritium activity. Counts per minute per group (means +/- SE) were as follows: sedentary, 6,839 +/- 1,461; handled, 8,959 +/- 1,576; voluntary runners, 13,126 +/- 2,069; and treadmill runners, 18,950 +/- 5,975. One-way analysis of variance and Tukey's highly significant difference test found the counts per minute of the treadmill runners to be significantly different from the counts per minute of the sedentary animals. These results indicate that the responsiveness of spleen lymphocytes to Con-A increases as the level of stress and exercise increases.

Basketball exercise and secretory immunoglobulin A.

This study examined saliva levels of immunoglobulin A (IgA) before and after three games and three practice sessions during the basketball season. Saliva was collected from 27 prepubescent boys (10-12 years) in a small Fry league and 23 postpubescent boys (16-18 years) on a high school varsity team. Saliva samples were frozen for later assay using a standard enzyme-linked immunosorbent assay technique. IgA levels were significantly increased after games 1 and 3 in both age groups and after practice 3 in the high school athletes. Over the 2 months of saliva collections the pre-exercise IgA increased significantly with games 2 and 3 higher than game 1, and practice 3 higher than practices 1 and 2, in both age groups. These results indicate that basketball exercise can increase saliva IgA levels and that chronic exercise over the basketball season may increase the resting levels of IgA. These changes may give athletes more protection against respiratory infections both after exercise and in the resting state later in the season.

The effect of exercise intensity and duration on salivary immunoglobulin A.

Two experiments were performed to examine salivary immunoglobulin A (s-IgA) responses to varying levels of exercise intensity and duration. For experiment 1, 9 college men (mean age, SD = 23.56, 1.64 years) completed treadmill runs of 15, 30, and 45 min at approximately 60% of maximum oxygen consumption (VO2max). For experiment 2, 9 other college men (mean age, SD = 23.67, 2.0 years) ran for 20 min at approximately 50, 65 and 80% of VO2max. Unstimulated salivary samples were collected before, and immediately, 1 and 2 h after the exercise. Samples were assayed for s-IgA using an enzyme-linked immunosorbent assay. Mean s-IgA levels did not change significantly (P greater than 0.05) at any of the post-exercise collection times when compared to pre-exercise levels. The results of this investigation indicated that running at intensities of 50-80% of VO2max and for durations of 15-45 min did not affect s-IgA levels.

The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold.

The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT.

Factors affecting the estimation of physical working capacity at the fatigue threshold.

The purpose of this study was to investigate potential improvements in the methodology associated with the Physical Working Capacity at the Fatigue Threshold (PWCFT) test including: (1) the use of a continuous test protocol; (2) the use of a treadmill; (3) the use of a bipolar EMG lead system for noisy electronic environments; and (4) the potential for residual fatigue from tests repeated 24 hours apart. The results of the continuous test protocol (mean +/- S.D. = 210 +/- 73 watts) correlated well (r = 0.856) with the original discontinuous technique (222 +/- 83 watts) and there was no significant (p greater than 0.05) difference between the mean values (t = 1.146). Treadmill testing required a bipolar lead system to counteract the electrical noise generated by the treadmill motor. The heart rate values which corresponded to PWCFT on the treadmill (mean +/- s.d. = 164 +/- b.p.m.) and bicycle ergometer (153 +/- 18 b.p.m.) were highly correlated (r = 0.833) and there was no significant (p greater than 0.05) difference between the mean values (t = 2.22). The use of a bipolar lead EMG system on the bicycle ergometer resulted in significantly (p less than 0.05) smaller voltage for any given power output, and the PWCFT exhibited a low to moderate correlation (r = 0.60) with PWCFT derived from a unipolar arrangement. The test-retest results of discontinuous PWCFT measurements performed 24 hours apart on the bicycle ergometer were correlated at r = 0.812 with no significant (p greater than 0.05) difference (t = 0.52) between the mean values (test = 198 +/- 60; retest = 191 +/- 63 watts).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of saliva immunoglobulin levels by swim training.

Saliva immunoglobulin A (IgA) and cortisol levels were measured in 21 male members of a major midwestern swim team. Saliva samples were collected before and after training sessions four times during the fall season; the training intensity was light, moderate, heavy and during the taper period before a major competitive meet. Saliva IgA levels were decreased after each training session, reaching statistical significance with the moderate training intensity. Over the 3-month training period the pre-session and post-session IgA levels both decreased significantly during the heavy and taper training intensities later in the fall season. Cortisol levels were significantly elevated only after the heavy-intensity training session. The Profile of Mood States (POMS) was used to assess the swimmers' overall mood on each test day. No significant correlations were found between the global POMS score and IgA or cortisol. Also, cortisol and IgA were not significantly correlated except after the light training session. Results from this study indicate that acute bouts of exercise can reduce salivary IgA levels and that chronic exercise of high intensity can reduce the resting levels of IgA. These changes may render the athletes more vulnerable to respiratory infections after exercise and even at rest during the later stages of the competitive season.

Strength and anaerobic responses of elite young female sprint and distance runners.

The purpose of this study was to assess the strength and anaerobic responses of elite young female runners, in order to determine the relationship of these characteristics to age and high proficiency in sprint events. Thirty-one national junior-level sprint and middle distance runners were evaluated for isokinetic peak torque for leg extension at velocities ranging for 30 degrees to 300 degrees X s-1, anaerobic power and capacity based on the Wingate test, and body composition based on underwater weighing. Age-related and event-related differences were noted for both the peak torque and anaerobic response measures. Peak torques were greater for the older (greater than 11.67 yr) runners and greater for the sprinters when measured at the higher testing velocities. Anaerobic power and capacity were also greater for the older runners, but event-related differences only appeared when anaerobic power was adjusted for fat-free weight (adjusted anaerobic power was greater in the older sprinters). These results indicate that both age and fat-free weight influence strength and anaerobic responses in young female runners and that exceptional levels of such characteristics only appear for sprinters within the upper age groups of youth competition.

Validity of anthropometric equations for the estimation of body density in adolescent athletes.

One hundred forty-one adolescent male (age: X +/- SD = 17.43 +/- 0.96 yr) and 133 adolescent female (16.51 +/- 1.39 yr) athletes were studied to determine the validity of available anthropometric equations for estimating body density (BD). Anthropometric measures were taken of eight skinfolds, nine circumferences, and four diameters. Body density, determined by underwater weighing (corrected for residual lung volume), was 1.080 +/- 0.010 g X ml-1 for the males and 1.066 +/- 0.010 g X ml-1 for the females. Cross-validation of 17 selected equations on the males revealed validity coefficients ranging from R2 = 0.29-0.67 and total-error scores ranging from 0.0062-0.0277 g X ml-1. Among the females, cross-validation of 15 selected equations revealed validity coefficients ranging from R2 = 0.31-0.67 and total-error scores ranging from 0.0064-0.0214 g X ml-1. While equations of either linear or quadratic form demonstrated acceptable accuracy in the estimation of male BD values, only quadratic equations displayed similar levels of accuracy among the females. Based on these results, as well as consideration of characteristics related to inter-tester error and the variance of predicted scores, the quadratic equations of Jackson and Pollock, Lohman, and Pollock et al., as well as the linear equation of Forsyth and Sinning, were found to be particularly appropriate for the estimation of BD in adolescent athletes.

Chronic exercise and cardiac vascularization.

Male albino rats were trained on a motorized treadmill for 8 weeks, using eight training regimens which varied in severity from 0.313 m . s-1, 3 days/week for 30 min each day, to 0.447 m . s-1, 5 days/week for 60 min each day. At the end of the 8 week training period, the animals were anesthetized and Pelikan ink infused retrogradely through the aorta, into the coronary arteries and capillaries of the heart. The hearts were sectioned, stained and examined for the number of capillaries per mm2 and the capillary/muscle fiber (C/F) ratios. Six of the eight exercise groups had capillary densities significantly lower than the density in the sedentary control group of 3,022 cap mm-2. Likewise, five of the exercise groups had significantly lower C/F ratios than the sedentary group ratio of 1.077. The difficulties inherent in identification of cardiac muscle fibers make the C/F ratio a weaker measurement for determining cardiac vascularity. The lower capillary density in the trained hearts could be produced by muscle fiber hypertrophy which would push the capillaries farther apart. It is concluded that exercise training does not stimulate the multiplication of cardiac capillaries. The beneficial effect of exercise on the heart is probably a result of enlargement of the coronary arteries or the collateral circulation.

Body composition and somatotype characteristics of junior Olympic athletes.

Body composition and somatotype were determined in Junior Olympic competitors to evaluate the structural characteristics concomitant to high proficiency in various athletic activities. Underwater weighings and anthropometric determinations of somatotype were performed on 145 male and 133 female adolescent participants in national meet competition in the sports of track and field, gymnastics, diving, and wrestling. The most frequent differences within either the male or female Junior Olympic samples involved the performers in throwing events (shot put, discus, and javelin), who were taller, heavier, fatter, and of unique somatotype when compared to all or most other competitors. Additional structural differences, generally of a lesser magnitude, also existed between other groups of Junior Olympians. Differences in body composition characteristics were also noted when Junior Olympians were compared with other adolescent athletes or non-athletes.

Effects of chronic exercise on the ultrastructure of the adrenocortical cells in the rat.

Four groups of male rats were exercised for periods of 2, 4, 6, and 8 weeks with controls in each group. As a result of chronic exercise there was an increase in the width of the zona fasciculata of the adrenal cortex. Also, there was an increase in the number and size of the mitochondria, and an increase in the quantity of smooth endoplasmic reticulum, and during the first 4 weeks of exercise an increase in the number of lipid droplets in the zona fasciculata. The close relationship between the smooth endoplasmic reticulum and the mitochondria, and the relationship between the smooth endoplasmic reticulum and the lipid droplets suggests a possible means for a transport mechanism for movement of precursors between these organelles.

Emotionality changes in rats following chronic exercise.

The effect of chronic endurance exercise on the emotionality of male albino rats was studied in five experimental groups: Controls, Runners, Walkers, Swimmers and Waders. Runners and Swimmers were trained for 8 weeks using programs which produced significant bradycardia and cardiac hypertrophy. Walkers and Waders received comparable handling and exposure to the psychological aspects of the treadmill running and swimming routines but were not physically trained. The Control group was allowed only home cage activity. After 8 weeks all animals were tested for their level of emotionality using the tunnel emergence test and the open field test. The emergence test was judged to be too stressful for the Sasco rat strain used in this study since many rats failed to emerge in one hour. Three measurements in the open field: urination, defecation and central squares also lacked power to discriminate emotionality because of their very low level of occurrence. The Control rats had significantly longer latency times, which indicates that the additional handling received by the other groups reduced their emotionality. The significantly larger number of total squares entered by the Runners and Swimmers supports the hypothesis that chronic physical exercise does function to lower emotionality in the rat.

The role of glucocorticoids in exercise.

From the literature we can make the following statements concerning the role of glucocorticoids in exercise and training. These conclusions are summarized graphically in Figure 3. 1. The principle physiological functions of glucocorticoids are stimulation of gluconeogenesis and mobilization of amino acids and fatty acids from body stores. 2. Injected glucocorticoids produce significant increases in the work produced by isolated muscle and by intact animals. 3. Light to moderate exercise work loads may produce an increase, decrease or no change in plasma glucocorticoid (GC) levels; depending on the degree of psychological and/or physiological stress involved in the exercise. 4. In moderate to exhaustive exercise the plasma GC levels progressively increase. In some subjects (especially animals) exhaustion produces a decrease in plasma GC which may represent a defense mechanism to prevent depletion of body resources. 5. Chronic exercise training produces adrenal cortex hypertrophy and usually a smaller rise in plasma GC during an acute exercise bout than that obtained with nontrained subjects. The resting GC levels frequently increase initially during training but return to normal as the trained state is reached. 6. The changes in GC response during training appear to be produced by decreased responsiveness of the adrenal cortex itself to ACTH stimulation and possibly by adaptation of the hypothalamus-hypophysis axis which reduces the ACTH released in response to stress. 7. The many combinations of psychological and physiological stress present in different exercise regimens probably account for the variety of GC responses to exercise reported in the literature.