Influence of exercise training on maternal and fetal morphological characteristics in the rat

Evidence in both humans and animals has shown that exercise before or during pregnancy may effect fetal outcome. The purpose of this investigation was to examine the effects of an exercise program on fetal development in the rat. Prior to impregnation one group of animals was exercise-trained on a Quinton shock-stimulus rodent treadmill. The exercised group was trained to run 5 days/wk, for 2.0 h/day at 31 m/min up an 8 degree incline for 8 wk before mating. Following mating the training intensity was reduced to 27 m/min up a 5 degree incline, and the exercise period decreased to 1 h/day. On day 19 of gestation, 24 h postexercise for the trained mothers, the animals were killed in the fed state and the maternal and fetal characteristics were measured. The sedentary controls gained significantly (P less than 0.05) more body weight during pregnancy. This can be attributed to three factors: higher number of fetuses, 14.83 +/- 0.04 vs. 12.2 +/- 0.85 for the trained; larger litter weights, 44.25 +/- 4.97 vs. 26.17 +/- 1.82 g/dam for the trained; and slightly larger lipid stores. In addition to having fewer pups the trained mothers had a greater number of fetal resorptions; 0.9/dam as opposed to 0.17/dam for the sedentary control. Analysis of fetal body composition showed no difference in total body water, protein, or fat between the pups of sedentary and trained dams. The results of this study indicate that exercise training prior to and during pregnancy influences fetal development in the rat.

Effects of Shock Inputs on Perceptual Vigilance

This study concerns the role of an accessory shock stimulus in varying the level of performance of subjects in reporting pairs of tachistoscopic words. On half the trials subjects received either a high or low level of shock together with a pair of words presented for one of two durations. The results indicate that intensity of shock interacted with sex such that for female subjects performance deteriorates with intensity in shock while for male subjects it increases. The role of phasic and tonic arousal is discussed.

Temperature Effects on Acceleration of Rainbow Trout, Salmo gairdneri

Acceleration performance during and immediately following fast-starts was measured at 5, 10, 15, 20, and 25 °C for rainbow trout (Salmo gairdneri) of mean mass 23.5 g. Fast-start responses were initiated by an electric shock stimulus. Temperature had little effect on fast-start kinematics. Response latency and duration of propulsion strokes decreased with temperature. Latencies decreased from 23 ms at 5 °C to 6 ms at 25 °C. Times to complete the first two principal acceleration strokes in a fast-start decreased from 116 ms at 5 °C to 65 ms at 25 °C. Distance traveled in a given time increased with temperature. For an elapsed time of 100 ms, the distance traveled was 3.5 cm at 5 °C increasing to 11.3 cm at 25 °C. Velocity increased with time at each temperature to reach maximum values by the end of the third propulsive stroke and thereafter declining. Maximum velocity increased with temperature from 0.99 m∙s−1 at 5 °C to 1.71 m∙s−1 at 15 °C. Maximum velocity was independent of temperature from 15 to 25 °C. Similar trends were found for maximum acceleration rate which increased from 16 m∙s−2 at 5 °C to 41 m∙s−2 over the 15–25 °C range. Temperature effects on acceleration performance would alter the ability of fish to traverse short areas of high velocity flow, the effectiveness of predators, and vulnerability of prey fish. Key words: trout, acceleration, swimming, fast-start, temperature, predation, locomotion

Effects of “Neutral Hypnosis” on a Conditioned Physiological Response

The objective of the present experiment was to determine whether hypnosis without explicit suggestion of analgesia would diminish physiological responses to an operationally defined painful shock stimulus. Muscle tension (EMG) was significantly lower during hypnosis than pre- or posthypnosis. Pulse rate remained stable throughout all conditions. Also, the question of whether a tone paired with shock might acquire some unique property because of that association was investigated. It was found that EMG response to the tone alone was significantly greater than to the tone-shock combination, in prehypnosis and posthypnosis, but not during hypnosis.

Use of an Electrified Center Board in the Study of Chicks on the Visual Cliff

An electrified grid was used with chicks to reduce latencies and no-response trials on the visual cliff. No significant difference in percentages of deep and shallow side descents was found between the shocked and non-shocked groups. The shocked group had significantly lower latencies and it had no no-descent trials. It was concluded that some improvement in the efficiency of experimentation with the chick might be achieved by the application of a shock stimulus.