W. D. Van Huss

Effects of a 6-month incentive-based exercise program on adherence and work capacity

The purpose of the study was to evaluate the effect of behavioral management techniques on exercise adherence linked to improvements in work capacity and maximal oxygen consumption (VO2max). One hundred thirty-seven participants in six different worksites on a university campus (five experimental and one comparison site) completed 6 months of a minimally supervised, incentive-based endurance exercise program. All participants in the experimental group contracted to engage in at least four bouts of 30 min of verified aerobic exercise within a prescribed target heart rate range each week for the duration of the program. Forty dollars deposited at the beginning of the program served as a response cost that could be lost as a result of failure to fulfill the weekly contracts. Individuals in the comparison group participated in a similar 6-month program but without the contracts and response cost strategies. Weekly adherence for both groups was strictly defined as verified fulfillment of all four bouts of exercise. Adherence for the experimental group was 97% by this definition, and adherence for the comparison group was 19% (P less than 0.01). VO2max increased 2.6% (P less than 0.01), and treadmill test time increased 16% (P less than 0.01) in the experimental group after the 6-month program, with no significant changes in the comparison group. Recovery heart rates at 2 and 4 min post-exercise were significantly lower at 6 months in the experimental group but not in the comparison group. These data provide evidence that adherence to a 6-month endurance exercise program can be improved significantly through the use of well conceived behavior management strategies.(ABSTRACT TRUNCATED AT 250 WORDS)

DETERMINATION OF BODY DENSITY BY AIR DISPLACEMENT, HELIUM DILUTION, AND UNDERWATER WEIGHING.

Many research workers have attempted to use density as an objective means of predicting the gross composition of live animals and human beings. Behnke et al. (1942) were able to determine the body specific gravity of human beings quite accurately by underwater weighing. This method has been used as the standard of comparison in subsequent studies ( Welham and Behnke, 1942; Broiek, 1946; Osserman et al., 1950; Dupertuis et al., 1951). The underwater weighing technique has also been widely used for predicting the composition of animal carcasses and cuts ( DaCosta and Clayton, 1950; Brown et al., 1951; Kraybill et al., 1952; Whiteman et al., 1953; Pearson et al., 1956; Price et al., 1957; Kirton and Barton, 1958). However, underwater weighing has limitations, and other methods must be used to determine the density of sick and infirm individuals and living animals. Several German workers ( Pfaundler, 1916; Pfleiderer, 1929; Bohnenkamp and Schmah, 1931) used a method called “air displacement” to determine the density of human beings. Kohlrausch in 1929 used the same method for studying the effect of exercise on dogs, and Liuzzo (1958) used air displacement to determine the body density of live guinea pigs. In 1953, Wasler and Stein developed the helium dilution method and used it to determine the density of live cats. Siri (1955) greatly improved on this method and subsequently used it to determine the body density of human beings . Two studies on determination of body density are reported herein. In the first experiment the objectives were to determine the densities of human beings by air displacement and to correlate these values with the densities obtained by underwater weighing. The purposes of the second study were to determine the densities of live pigs by air displacement and helium dilution and to correlate the values with body composition as determined by chemical analysis.

Effect of Overload Warm-up on the Velocity and Accuracy of Throwing

(1962). Effect of Overload Warm-up on the Velocity and Accuracy of Throwing. Research Quarterly. American Association for Health, Physical Education and Recreation: Vol. 33, No. 3, pp. 472-475.

Effects of swimming on dystrophic Syrian hamster heart.

Morphological and histopathological heart changes were determined for sixteen dystrophic Syrian hamsters (B10 14.6 strain) and sixteen normal hamsters. Eight animals were randomly assigned to each of the following groups: dystrophic swim (DYS-SWM), dystrophic sedentary (DSY-SED), normal swim (NOR-SWM), and normal sedentary (NOR-SED). The daily swimming program consisted of an initial 30-minute swim which was gradually extended to 60 minutes by the end of eight weeks. Weights up to 3% body weight were attached during swimming to increase the work load. Sedentary animals received no experimental treatment. Four animals in each group were sacrificed at 4 and 8 weeks after the initiation of treatments. In comparison with the two groups of sedentary animals, the NOR-SWM group had a greater heart weight/body weight ratio at both 4 and 8 weeks (P less than .05), while the DYS-SWM group had an increased ratio only at 8 weeks (P less than .05). Subjective histopathological evaluation of heart lesions showed that the DYS-SED group had many large areas of inflammatory reaction with infrequent diffuse areas of calcification. In contrast, the DYS-SWM group had fewer and smaller areas of inflammatory reaction with moderate amounts of calcification.

Separate and simultaneous effects of aerobic exercise and anxiety on myocardial damage in the rat

The purpose of this study was to determine the effects of various programs of physical activity on anxiety-related myocardial damage in rats. The anxiety-producing stress consisted of randomly distributed applications of a disturbing but nonpainful electrical shock. Physical activity consisted of long-duration, low-speed running. Three hundred and seventy-five male albino rats were randomly assigned to five comparison groups. The results show that the anxiety treatment produced marked myocardial damage. Animals preconditioned by eight weeks of exercise prior to the introduction of the anxiety treatment did not suffer as much myocardial damage as did animals that were not preconditioned. However, a group in which exercise and anxiety were introduced simultaneously had the highest incidence of myocardial necrosis. We conclude that aerobic exercise can modify the effects of a subsequent or simultaneous anxiety-producing stressful situation on the myocardium of the laboratory rat. The time at which the exercise is imposed determined the nature of the effect.