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Biomedical subjects

J J Ayres

Publications and source records attributed to J J Ayres.

7 recordsLinked to original sources
PubMed1992

One-trial backward excitatory fear conditioning transfers across contexts.

One path to human phobia may be one-trial backward fear conditioning. Human phobias transfer readily across contexts. However, animal studies of one-trial backward fear conditioning have yet to demonstrate such transfer. The present study sought to do so. It used a lick-suppression procedure with 84 naive male albino rats. Two conditioning contexts, designated O and V, were crossed factorially with two test contexts, O and V. Within each cell of the factorial design, rats received in the conditioning context either a single 12 sec tone backward paired with a single 4 sec 1 mA shock or the same tone explicitly unpaired with shock. Fear of context and fear of tone were subsequently assessed in terms of the suppression of licking that they evoked. Test results suggested that (1) the rats discriminated between contexts O and V, and (2) despite such discrimination, one-trial backward fear conditioning transferred across the two contexts. The results enhance the plausibility of one-trial backward fear conditioning as a source of human phobia.

Animals↗
PubMed1979

Physiologic effects on adult men of circuit strength training and jogging.

The purpose of this study was to determine the effects of 8 weeks of circuit strength training (CST) followed by 8 weeks of jogging and then 8 weeks, of CST or jogging. During the final 8 weeks, the subjects were randomly assigned to either CST or jogging groups. The subjects (n=16, x age = 29 yrs) exercised 3 days/week. The strength training involved 2 circuits of reciprocal exercises using isokinetic devices with 10 to 15 repetitions/set and 30 seconds of rest between sets. The subjects jogged 3 miles/day during the jogging program. After the initial 8 weeks of CST, significant changes were found in treadmill performance time, maximum oxygen uptake (VO2max), maximum pulmonary ventilation (VEmax), body fat, total skinfold fat, fat weight, lean weight, isotonic bench and leg press, and isokinetic slow speed, fast speed, and power endurance measures. The jogging program elicited significantly greater changes in treadmill performance time and VO2max. Further reductions were found in total skinfolds and waist girth during the jogging program. Leg strength was maintained during jogging but upper body strength was reduced significantly. Physiologic levels were maintained during the final 8 weeks and showed no differences between the CST and jogging groups.

Adult↗
PubMed1978

A comparison of body fat determined by underwater weighing and volume displacement.

Two hydrostatic techniques, underwater weighing and water displacement, were used to determine body fat for 67 volunteer men between 25 and 61 yr of age (-/x=41 yr). All tests were administered in random order in the morning on the same day while subjects were in the postabsorptive state. Test-retest reliabilities for the underwater weighing and water displacement techniques were 0.995 and 0.96, respectively. The correlation between the two hydrostatic techniques was r=0.96. The mean percent fat determined by underwater weighing (-/x=20.1 +/- 6.4) and water displacement (-/x=19.4 +/- 6.1) were significantly different (t=28.16; df=65; P less than 0.001). These analyses showed that both techniques were reliable in measuring percent body fat, but produced slight systematic differences. Regression equations were provided to adjust for the difference.

Adipose Tissue↗
PubMed1978

The effect of circuit weight training on strength, cardiorespiratory function, and body composition of adult men.

The purpose of this study was to determine the changes elicited by circuit weight training (CWT) and running (RN) programs conducted 3 days/week for 20 weeks. Subjects were randomly assigned to one of three groups: CWT (n = 11); RN (n = 16); and control (n = 14). CWT consisted of 10 exercises performed in 2 sets of 15 reps with 20 to 25 sec rest between exercises. CWT workout time decreased from 30 min to 23 min; exercise heart rate (HR) increased from 79% to 84% max; average weight increased from 42% to 56% of max 1 RM strength and total weight increased 81% (1506 to 2720 lbs/workout). The RN group exercised at 85% max HR for 23 to 27 min/workout. Multivariate and step-down analyses showed the CWT group to be significantly different from the control group at the end of 20 weeks in leg press strength, fat weight, and Vo2 max (1/min). The RN group was significantly different from the CWT group in Vo2 max and treadmill time. Univariate analyses revealed no differences between the CWT and control groups in Vo2 max expressed as ml/kg LBW.min but did show a significant superiority of the RN group over the other two groups in this variable. It was concluded that the CWT program was most specific in improving strength and changing body composition and produced only a small aerobic effect as measured on the treadmill running test.

Adult↗
PubMed1976

A comparative analysis of four protocols for maximal treadmill stress testing.

The purpose of this investigation was to compare the results from four commonly used maximal treadmill stress tests: Balke, Bruce, Ellestad, and a continuous multistage running protocol. The results compared serial and maximal heart rate, metabolic demands, and ECG determinations. Fifty-one healthy men, 35 to 55 years of age, volunteered for this study and were dichotomized into trained and untrained subjects. Regression analyses showed all the tests to correlate highly. No significant differences were found between tests at maximum for V02, heart rate, and blood pressure, except for V02 for the Balke as compared to the running protocol (39 vs. 41 ml./Kg-min). The Balke protocol showed lower values at maximum in VE and RP than the other three tests as well as the most gradual rate of progression in MET cost (0.5 METS per minute). The increase for the Bruce and Ellestad tests was from 1 to 1.5 METS per minute, and a rapid initial increase (9 METS in the first 3 minutes) made the running test undesirable as a screening method. Although serial plots of heart rate and MET costs were similar to those previously reported for different population samples, the present data further refined these values. Finally, a nomograph comparing treadmill time and V02, max. for the Balke, Bruce, and Ellestad tests was developed from these data.

Adult↗