Biomedical subjects

N W Eastman

Publications and source records attributed to N W Eastman.

9 recordsLinked to original sources

PubMed1994

Resistance exercise decreases beta-endorphin immunoreactivity.

Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To examine further the effects of resistance exercise on beta-EP immunoreactivity, 10 male and 10 female college-age students participated in a series of controlled isotonic resistance exercises. The session consisted of three sets of eight repetitions at 80% of one repetition maximum (1-RM) for each of the following exercises: (1) bench press; (2) lateral pull-downs; (3) seated arm curls; and (4) military press. Blood plasma was sampled both before and after the lifting routine and beta-endorphin levels were determined by radioimmunoassay. A Students t test for paired samples indicated that mean(s.e.) plasma beta-endorphin levels after exercise (10.5(1.3) pg beta-EP ml-1) were significantly decreased as compared with pre-exercise (control) levels (16.5(1.2), P < 0.05). While the mechanism(s) contributing to the decrease in immunoreactivity is unclear, it may be the result of the synergistic effect of beta-EP clearance during rest intervals and changes in psychological states between sampling.

Adult↗

PubMed1994

Athletic injury and self diminution.

A review of the literature examining the effects of athletic injury on persons have suggested a deleterious effect. Specifically, results indicated that following traumatic injury, athletes suffer a diminution of affect and feelings of self-worth. Because studies published in this area have been post-injury in design, the present study was fashioned to examine changes from baseline values in the self-concept of university varsity football players following a disabling injury. There were 29 athletes in the subject pool. Sixteen subjects were severely injured during the season. Measures were taken on the first day of fall practice and at the end of the season. Injured athletes were assessed each week while they were unable to participate in practice. Analysis revealed a significant decrease in generalized self-concept following athletic injury (p < 0.001) which persisted through the course of treatment. Suggestions for continued research and treatment are proffered.

Adolescent↗

PubMed1993

Plasma beta-endorphin immunoreactivity: response to resistance exercise.

Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To further examine the effects of resistance exercise on beta-endorphin immunoreactivity, six resistance-trained athletes participated in a three-set series of eight repetitions of isotonic exercise. All exercises were performed at 80% maximal effort. Blood was sampled from the group by venepuncture, both prior to and following the exercise bout, and beta-endorphin concentration was determined by radioimmunoassay. The results indicated that mean (+/- S.E.) plasma levels of beta-endorphins following exercise (18.04 +/- 3.4 pg beta-EP ml-1) were not significantly changed from pre-exercise (control) levels (19.59 +/- 2.4 pg beta-EP ml-1), although there was considerable inter-individual variability. Our results support previous research which has reported no significant changes in beta-endorphin immunoreactivity following resistance exercise, as well as reported findings of considerable variability in the beta-endorphin response to exercise.

Adult↗

PubMed1993

Beta-endorphin response to endurance exercise: relationship to exercise dependence.

Considerable research has shown significant increases in beta-endorphin levels after aerobic activity. These increases and their accompanying euphoric effect have been suggested as a possible psychophysiological mechanism underlying the exercise-dependence syndrome. The relationship between plasma beta-endorphin levels and a tendency towards exercise dependence, however, has not been established. To examine this relationship, 8 women trained in aerobic dance completed an exercise-dependence assessment prior to participation in a 45-min. session of continuous aerobic dance. Plasma beta-endorphin concentration was measured both prior to and following the aerobics routine. A Student t test for paired observations indicated that mean plasma beta-endorphin levels (+/- SE) were significantly higher after the aerobics routine (11.96 +/- 1.3 pg beta-EP.ml-1) than preexercise levels (8.62 +/- 1.4). However, beta-endorphin difference values (% change) were not significantly correlated with scores on the exercise-dependence survey. Those data suggest that scores on exercise dependence are not related to changes in plasma beta-endorphin levels after aerobic exercise.

Adult↗

PubMed1992

Effect of induced alkalosis on swimming time trials.

Previous studies have shown that sodium bicarbonate ingestion prior to exercise may improve performance during repeated (interval) bouts. To examine the practical implications of such findings, seven collegiate swimmers participated in simulated swim competitions of multiple events following sodium bicarbonate (B) ingestion, placebo (P) ingestion and control (C--no ingestion) treatments. Each swimmer reported to the laboratory 1 h prior to the simulated competitions (72 h apart) and was randomly assigned to one of the three experimental treatments. Competition consisted of one relay (100 yards; 91.4 m) and two individual (200 yards; 182.8 m) swimming events with 20 min rest between events. Analysis of variance (ANOVA) with repeated measures revealed no significant differences in performance times as a result of the three treatments (P greater than 0.05). The results suggest that sodium bicarbonate ingestion prior to swim competition consisting of significant rest intervals between events is not an ergogenic procedure.

Adult↗

PubMed1992

Metabolic demands and perceived exertion during cardiopulmonary resuscitation.

Emergency situations often require continuous execution of one-person cardiopulmonary resuscitation (CPR) for periods of time in excess of 30 minutes. The limited research which has examined the demands of the procedure has focused on central physiological measures, despite (1) the use of a subjective end-point for termination of CPR (i.e., exhaustion) as stated in professional guidelines, and (2) significant peripheral involvement in the form of muscular exertion, a phenomenon more closely linked to Ratings of Perceived Exertion (RPE) than to central factors. To examine subjective responses to performing CPR, 8 healthy, sedentary subjects [M age = 20.8 (yr) +/- .4; weight (kg) 82.6 +/- 7.1; height (cm) 183.7 +/- 2.8] reported differentiated Ratings of Perceived Exertion (RPE) following 10 minutes of one-person CPR testing. While metabolic data observed during CPR support previous research suggesting that the energy demands of performing CPR are relatively low, both peripheral and over-all RPE were significantly higher than central (respiratory-metabolic) RPE. Over-all RPE was also significantly greater than peripheral RPE. The data suggest research investigating CPR demands based on central measures may underestimate actual as well as perceived demands of performing the procedure. In addition, the considerable interindividual variability in the relative energy cost (% VO2 max) of performing one-person CPR suggests that the fitness level of the individual may be a limiting factor in the ability to perform CPR for extended periods of time.

Adult↗

PubMed1991

Effects of hyperbaric simulation of scuba diving pressure on plasma beta-endorphin.

In contrast to our previous studies on the submersion of scuba divers in a state of neutral buoyancy, neither plasma beta-endorphin-like immunoreactivity (beta-EIR) nor affective feelings were significantly changes in scuba divers by mimicking diving pressures of 2 feet (0.6 m) and 50 feet (15.2 m) for 20 min in a hyperbaric chamber. It is concluded that the submersion-induced increase in plasma beta-EIR and accompanying changes in affect reported previously are not due solely to changes in pressure.

Adult↗

PubMed1991

Effects of diving experience on submersion-induced increases in plasma levels of beta-endorphin in scuba divers.

The submersion of eight male scuba divers in a state of neutral buoyancy for 20 min resulted in a significant increase (mean, 20%) in plasma beta-endorphin immunoreactivity (beta-EIR), and all subjects reported post-submersion feelings of well-being, relaxation or euphoria. The increase in beta-EIR was negatively correlated with age (r = -0.727) and diving experience (r = -0.860), and positively correlated with the amount of air usage during submersion (r = 0.863). Thus, diving experience appears to influence many of the nonsubjective parameters measured.

Adult↗

PubMed1987

Increased plasma beta-endorphin immunoreactivity in scuba divers after submersion.

Increased plasma beta-endorphin immunoreactivity in scuba divers after submersion. Med. Sci. Sports Exerc., Vol. 19, No. 2, pp. 87-90, 1987. After submersion under water in a motionless state of neutral buoyancy, scuba divers frequently report feelings of well-being or euphoria similar to those reported after strenuous exercise. Since strenuous exercise is associated with a stress-related increase in plasma beta-endorphin immunoreactivity (beta-EIR), this study was undertaken to measure plasma beta-EIR after submersion in a state of neutral buoyancy under conditions that do not involve strenuous exercise or other extreme stresses. Plasma beta-EIR was measured by radioimmunoassay in male scuba divers before and immediately after remaining motionless 10 ft under water in a state of neutral buoyancy. A significant (P less than 0.01) increase in plasma beta-EIR was found under these conditions. Venipuncture and scuba breathing out of the water did not alter beta-EIR levels. These results indicate that the milder stress associated with submersion in a state of neutral buoyancy involves an increase in plasma beta-EIR similar to that caused by severe stress.

Diving↗