Swimming Program Research Articles

Increased hepatic glycogen synthetase and decreased phosphorylase in trained rats.

Rats were either physically trained by a 12 wk swimming program or were freely eating or weight matched, sedentary controls. Trained rats had a higher relative liver weight and total hepatic glycogen synthetase (EC 2.4.1.11) activity and a lower phosphorylase (EC 2.4.1.1) activity than the other groups of rats. These changes may partly explain the demonstrated training-induced increase in glucose tolerance. None of the findings could be ascribed to differences in foold intake or body weight.

Development and regression of exercise-induced cardiac hypertrophy in rats

Adult female rats were exercised by daily swimming. All the increase in heart weight induced by the exercise occurred within 14 days and averaged 30%. The half times of the increases in heart weight and total protein content were about 4.5 days, whereas that of cytochrome c, which was used as a mitochondrial marker, was 6.5 days. The total amounts of DNA and of hydroxyproline in the heart, which were used to evaluate the degree of connective tissue hyperplasia, increased only slightly (8% and 10%, respectively). Other animals were subjected to the same swimming program for 21 days. Groups of rats were killed at various time intervals after stopping exercise. Heart weight, total protein content, and total cytochrome c content decreased rapidly initially, with 60% of the total regression of hypertrophy occurring during the first week. Thereafter, heart weight fell more gradually toward the sedentary control value. The hydroxyproline content of the heart, which was increased 10%, did not decrease during the regression of the hypertrophy.

Clemson University Swimming Program: Putting Weigth Trained Tigers (and Tigresses) In the Tank

Clemson University Swimming Program: Putting Weigth Trained Tigers (and Tigresses) In the Tank

Neurodevelopmental treatment approach for teaching swimming to cerebral palsied children.

A model swimming program for cerebral palsied children based on the underlying principles of the neurodevelopmental treatment approach is presented following a review of the current literature pertaining to swimming programs for the physically handicapped and a discussion of the values of hydrotherapy.

Ventricular morphology and pumping ability of exercised spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) and two strains of normotensive Wistar rats were subjected to a 5 day/wk swimming program to determine whether the heart of the SHR could respond to an additional stimulus to cardiac growth. Swimming was tolerated well by all rats. Although body weight of the exercised groups was not significantly reduced, both the right and left ventricular weights of all exercised groups were increased. Left ventricular circumference and chamber volume were increased without a change in free wall thickness in all exercised groups. Ventricular performance was assessed by peak cardiac output and stroke volume attained during rapid intravenous volume loading, both before and after autonomic inhibition. After combined cholinergic and beta-adrenergic inhibition, all exercised rats had slower heart rates and higher peak stroke volume than respectively sedentary controls. Thus, exercised SHR had the same alterations in cardiac mass and performance as exercised normotensive rats. Despite the initial presence of left ventricular hypertrophy, the SHR responded appropriately to an additional stimulus for adaptive cardiac growth.

Cardiac responses to moderate training in rats.

Left ventricular (LV) performance was studied in 30 rats conditioned by swimming and in 27 sedentary controls. Hearts were studied in the open chest both during sinus rhythm and during atrial pacing. Afterload was increased by occlusion of the aorta. Sinus rates were 328 beats/min in sedentary and 300 in conditioned animals (P less than 0.01). During ejection (E), peak left ventricular systolic pressure (PLVSP) and maximum LV dP/dt were significantly higher in conditioned than in sedentary animals. When data from hearts matched for similar heart rates were compared, increased LV performance was still seen during aortic obstruction in conditioned animals. Performance at pacing rates up to 400 beats/min was similar in hearts from conditioned and sedentary animals. At pacing rates above 400 beats/min cardiac performance was less in sedentary than in the conditioned animals. These data illustrate that although base-line cardiac performance may be the same in rats conditioned by a moderate swimming program and in sedentary animals, cardiac reserve is improved by the swimming program.

Comparison of the effects of physical exercise, cold acclimation and repeated injections of isoprenaline on rat muscle enzymes.

The metabolic effects on rat cardiac and skeletal muscle of a strenous program of swimming, of cold acclimation and of isoprenaline treatment (0.3 mg/kg daily for 5 five-day weeks) were compared. Exercised and cold-exposed rats gained less body weight than did controls or isoprenaline-treated rats. In all treated groups the heart and the intercapular brown adipose tissue hypertrophied. The size of the adrenals increased only in isoprenaline-treated animals. Cold-acclimation and physical training increased and isoprenaline treatment reduced or did not affect the activities of succinate dehydrogenase, malate dehydrogenase and citrate synthase of cardiac muscle. In the skeletal muscle all treatments resulted in increased activities of these enzymes. Of the anaerobic enzymes analysed, only the activity of hexokinase increased in response to the treatements used. This increase was the same in cardiac as in skeletal muscle, but it was significantly greater with isoprenaline-treatment than with training or with cold-acclimation. The activities of lactate dehydrogenase and phosphofructokinase did not differ significantly. All treatments improved cold resistance, but only swimming exercise and cold acclimation significantly increased tolerance to exercise. It is concluded that prolonged stimulation of adrenergic beta-receptors by catecholamines is responsible for the metabolic changes observed.

Cardiac hypertrophy: synergistic effects of pericardiectomy and mild exercise in rats.

Removal of the pericardium in combination with a mild exercise program of swimming resulted in a significant increase in heart weight and heart weight/body weight ratio of young rats. Either exercise or pericardiectomy alone did not significantly alter these parameters as compared to the control group of rats. This finding further substantiates the pericardium's physiologic effect on the heart. The effects of pericardiectomy should be considered in experimental studies of cardiac hypertrophy and in clinical studies involving cardiac surgery.

Effects of physical training on several glycolytic enzymes in rat heart

In response to a program of daily swimming for 16 weeks, the activities of pyruvate kinase and lactate dehydrogenase increased significantly in the hearts of young male rats. The isozyme composition in M of cardiac lactate dehydrogenase increased from 28.5 to 32.7% in the trained animals. Phosphofructokinase activity and glycogen content were unchanged. The hearts of the exercising animals were 28% heavier than those of sedentary paired weight controls.

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.

Swim performance decrement over middle life

Swim records data from the U.S. Masters swim program afforded a chance to estimate the decline in swim performance over middle life. Men's records data indicated a falloff in swim performance of slightly less than one percent per year over the ages of 27.5 to 57.5 years. Men's decline in freestyle performance was seen to be essentially the same, regardless of varying oxygen requirements secondary to the distance swum. Men's decline in swim performance for the breaststroke and backstroke events was nearly that of the freestyle. Falloff in men's performance in the butterfly stroke rose to 1.47 percent per year. Women's times showed a decline between 20 to 50 percent greater than that seen for the men. Previous findings of athletes' decrease in pulmonary function over middle age closely parallel the observed decrease in Masters swimmers' records--approximately one percent per year.

Experimental observations on the effects of physical training upon intrinsic cardiac physiology and biochemistry

Hearts of rats conditioned by a moderate swimming program for 8 weeks were compared with hearts of sedentary animals. Hearts of conditioned rats had greater mechanical responses to tachycardia and to increases in preload and afterload, in part because of improved coronary blood flow and oxygen delivery. Energy stores and intermediary metabolism could not account for improved performance of conditioned hearts. Changes in the properties of myocardial contractile proteins with conditioning were characterized by increased adenosine triphosphatase (ATPase) activity and rates of superprecipitation of actomyosin and by alterations in the availability of sulfhydryl groups at the active site of myosin. Hearts of conditioned rats were partially resistant to hypoxia. During hypoxia they converted chemical energy to external work with greater efficiency than hearts of sedentary rats. The studies indicate that a moderate conditioning program in rats improves potential aerobic cardiac performance. Factors in this improvement include increased capacity for coronary flow and oxygen delivery and higher levels of actomyosin and myosin ATPase activity. Conditioning also confers partial resistance to hypoxia, apparently as a result of improved mechanisms of energy utilization.

Detailed Body Composition Analysis on Female Rats Subjected to a Program of Swimming

Detailed Body Composition Analysis on Female Rats Subjected to a Program of Swimming

An Elementary School Swimming Program

(1971). An Elementary School Swimming Program. Journal of Health, Physical Education, Recreation: Vol. 42, No. 2, pp. 87-89.

The effect of physical training upon the mechanical and metabolic performance of the rat heart

The dynamic and metabolic performance of rats conditioned by a swimming program (CH) and hearts of sedentary rats (SH) was studied in an isolated working rat heart apparatus. Heart rate, filling pressure, and afterload were controlled or kept constant, and heart weights were comparable in both groups. When compared with SH, CH had increased cardiac output and cardiac work. Atrial pacing at more rapid rates caused greater differences in these functions, and left ventricular pressure and maximal rate of pressure rise (dp/dt) became higher in CH than in SH. Atrial pacing was associated in CH with increased oxygen consumption but in SH by increased lactate and pyruvate production. When atrial filling pressure was elevated in order to perform ventricular function curves, CH showed greater dynamic responses than SH. There were also greater increments in oxygen consumption, and the ratio of aerobic to anaerobic energy production was also higher in CH. The mechanism of increasing oxygen consumption during stress in CH was mainly by improved coronary flow. In SH coronary flow did not change, but extraction of oxygen from the perfusing fluid increased. The results indicate that in physically trained rats the function of the heart as a pump is improved. These hearts have greater aerobic and mechanical reserve than hearts of sedentary animals. These effects appear to be at least partially due to improved mechanisms of oxygen delivery.

Glycogen, lipid, and high energy phosphate stores in hearts from conditioned rats.

Abstract Endogenous substrate stores and high energy phosphate levels were investigated in hearts of rats that had been subjected to a swimming program (CH) and were compared with matched sedentary controls (SH). Glycogen stores were elevated in CH after 5 weeks of training. After a vigorous swim, glycogenolysis occurred to the same residual glycogen level in CH and SH, but administration of isoproterenol caused a greater decline in cardiac glycogen in CH than in SH. Phospholipid levels were the same in CH and SH, but triglyceride levels tended to be lowest in CH. Triglycerides decreased during a strenuous swim. High energy phosphate and related compounds were the same in CH and SH.

Effects of weight changes produced by exercise, food restriction, or overeating on body composition.

The body weight of rats was reduced by exercise or by restriction of food intake over a period of 18 wk. Body composition was studied to determine if exercise protects against the loss of lean tissue that can occur as a result of a negative caloric balance. Rats weighing 706 +/-14 g were divided into four groups matched for weight. A baseline group was killed at the beginning of the study. An exercising group, fed ad lib., was subjected to a program of swimming. A sedentary, free-eating group was provided with food ad lib. Two sedentary, paired-weight subgroups were calorie restricted so that they lost weight at the same rate as the exercisers. The protein intake of one paired-weight subgroup was matched with that of the exercising group. The other sedentary, paired-weight animals ate the standard diet. There was no significant difference in body composition between the two sedentary, paired-weight subgroups which were, therefore, pooled for comparison with the other groups. The exercisers lost 182+/-19 g as a result of both an increase in caloric expenditure and a decrease in appetite. The sedentary, food-restricted animals lost an average of 182+/-18 g. The sedentary, free-eating animals gained 118+/-13 g. The carcasses of the exercised animals contained significantly less fat and more lean tissue than those of the sedentary, paired-weight animals, providing evidence for a fat mobilizing and protein conserving effect of exercise. The composition of the body substance lost by the exercising animals was 78% fat, 5% protein, 1% minerals, and 16% water, compared to 62% fat, 11% protein, 1% minerals, and 26% water for the sedentary, food-restricted rats. Fat accounted for 87% and water for 10% of the weight gained by the sedentary, free-eating animals.

Histochemical changes in rat skeletal muscle after exercise

Previous studies led us to suspect that the proportion of fibers within a given muscle which show relatively high activity of the enzymes associated with mitochondria should be related to the nature of the work load placed on that muscle. Following a 52-day swimming program for white rats (one and two 30-min exercise bouts each day) the proportion of fibers having intermediate and high malate dehydrogenase, succinate dehydrogenase, and reduced nicotinamide adenine dinucleotide diaphorase was not altered in the soleus. Neither was the proportion of fibers having low and high mitochondrial α-glycerophosphate dehydrogenase (mito α-GPD) and myosin adenosine triphosphatase altered in the soleus. Myosin adenosine triphosphatase showed no changes in the plantaris. However, the plantaris of moderately and heavily exercised rats did show a greater proportion of fibers having high malate and succinate dehydrogenase, and nicotinamide adenine dinucleotide diaphorase than did the plantaris of sedentary rats. This increase in the proportion of fibers having these high enzyme activities appears to be one mechanism through which a muscle can adapt to a chronic repetitive overload. If one wishes to think in terms of fiber types as determined by these enzymes, this study demonstrates that muscle fiber types can be changed in a nonpathologic condition.

Physical Therapy Swimming Program

Physical Therapy Swimming Program

A College-Run Recreational Swim Program for Fathers and Sons

A College-Run Recreational Swim Program for Fathers and Sons