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Biomedical subjects

J P Wallace

Publications and source records attributed to J P Wallace.

At least 19 recordsLinked to original sources
PubMed1996

Reliability and comparison of RPE during variable and constant exercise protocols performed by older women.

The purposes of this study were to assess if women 60 to 75 years of age perceived a series of exercise intensities differently from selected intensities in that series and to determine if a particular intensity was perceived more reliably. Twenty-four women (65 +/- 3.8 yr) completed a walking VO2max treadmill test. Subjects were either assigned to a variable, randomly ordered exercise protocol (GP1) or to one of three constant exercise protocols (Gps2-4). Each subject performed relative exercise intensities of 30, 50, and 70% of peak VO2 for three 5 min work bouts over 3 test days. Differences in RPE (p < 0.05) were found between each intensity and between the same intensities from both protocols. Women in GP1 rated exercise higher than women who exercised at a constant exercise intensity (p < 0.05). Intraclass correlation coefficients indicated that the exercise intensity of 50% of maximum was more reliable regardless of the protocol (Gp1: R = 0.97, Gp3: r = 0.94). When the RPE-HR correlation coefficients were transformed into a log scale, neither protocol had a stronger association (p > 0.05) between RPE-HR. It was concluded that older women should be given a range of exercise intensities that include the 50% relative exercise intensity as a perceptual marker in order to reach a reliable rate of exertion.

Aged↗
PubMed1995

Cardiovascular changes with age and exercise. A 28-year longitudinal study.

Various studies report a 0-22% per decade decline in circulatory function (VO2max) with advancing age. Twelve exercising men (E) were followed for 28 years, mean age 43 and 71 years, initial to final measurement, while 12 dropouts (C) detrained for 21 years, with a mean age from first to last measurement of 48 and 69 years, respectively. VO2 max in E changed from 45.9 to 39.4 ml.min-1.kg-1, 5% per decade, whereas C declined from 36.0 to 21.4 ml.min-1.kg-1, 19% per decade. Resting blood pressure was unchanged in E, 119/75 mmHg, whereas C rose from 128/85 to 149/90 mmHg. The data suggest that regular aerobic exercise forestalls the usual loss of circulatory function with increasing age.

Adult↗
PubMed1995

Twelve month adherence of adults who joined a fitness program with a spouse vs without a spouse.

OBJECTIVE: The purpose was to determine adherence of apparently healthy adults who joined an exercise program with a spouse (Married Pairs) vs. without a spouse (Married Singles). It was hypothesized that Married Pairs would have significantly higher adherence than Married Singles; and that self motivation would be associated with adherence. EXPERIMENTAL DESIGN: Twelve month adherence of Married Pairs and Married Singles were compared to self motivation in a retrospective design. SETTING: Subjects in this study did not volunteer for a scientific investigation, instead they were spontaneous participants in a university fitness program. PARTICIPANTS: Married Pairs were 16 couples and Married Singles were 16 married men and 14 married women. INTERVENTIONS: This study observed the 12 month spontaneous participation in a fitness program. The only intervention was the self motivation questionnaire. MEASURES: Adherence was defined as monthly attendance, compliance to the exercise prescription, dropout, and reason(s) for dropout. Self motivation was also measured. RESULTS: For Married Pairs, monthly attendance was significantly higher (54.2% +/- 10.3 vs 40.3% +/- 14.3) and dropout (6.3% vs 43.0%) was significantly lower than for Married Singles. Compliance to the exercise prescription was good for all of the groups except for the Married Single Men. Fifty percent of the dropouts left because of family responsibilities/lack of spousal support; 25% dropped-out to continue exercising on their own. Self motivation did not differ between Married Pairs and Married Singles. Monthly attendance of spouses in the Married Pairs demonstrated a significant correlation. CONCLUSIONS: Married Pairs had significantly higher attendance and lower dropout than Married Singles which appeared to be primarily influenced by spousal support rather than by self motivation.

Adult↗
PubMed1994

Dietary fat, sugar, and fiber predict body fat content.

OBJECTIVE: This study was conducted to determine the relationships among the specific components of dietary fat and carbohydrate and body fatness in lean and obese adults. DESIGN: Body composition determination was performed on each subject by hydrostatic weighing at residual volume. Subsequently, the individual components of dietary fat and carbohydrate were examined relative to body fatness using a 3-day food diary and a food frequency questionnaire. SUBJECTS: Subjects were 23 lean (11.1 +/- 2.9% body fat) men, 23 obese (29.2 +/- 3.8% body fat) men, 17 lean (16.7 +/- 3.3% body fat) women, and 15 obese (42.7 +/- 3.9% body fat) women who volunteered for free diet and body composition analyses. Inclusion criteria were 15% body fat for lean men, 25% for obese men, 20% for lean women, and 35% for obese women. STATISTICAL ANALYSIS PERFORMED: Group comparisons for dietary variables were made with a multivariate analysis of variance. RESULTS: No differences were found between lean and obese subjects for energy intake or total sugar intake, but obese subjects derived a greater portion of their energy from fat (33.1 +/- 2.6% and 36.3 +/- 2.3% for obese men and women, respectively, vs 29.1 +/- 1.3% and 29.6 +/- 2.0%, lean men and women, respectively). Percent of fat intake for saturated, monounsaturated, and polyunsaturated fats was not different among groups. Obese subjects derived a greater percentage of their sugar intake from added sugars than lean subjects (38.0 +/- 3.5% vs 25.2 +/- 2.0%, respectively, for men; 47.9 +/- 8.0% vs 31.4 +/- 3.4%, respectively, for women). Dietary fiber was lower for obese men (20.9 +/- 1.8 g) and women (15.7 +/- 1.1 g) than for lean men (27.0 +/- 1.8 g) and women (22.7 +/- 2.1 g). APPLICATIONS/CONCLUSIONS: Obesity is maintained primarily by a diet that is high in fat and added sugar and relatively low in fiber. Alterations in diet composition rather than energy intake may be a weight control strategy for overweight adults.

Adipose Tissue↗
PubMed1994

Influence of metabolic control on the ventilatory threshold in adults with non insulin-dependent diabetes mellitus.

Metabolic control, as assessed by glycosylated hemoglobin (HbA1c), has been reported to have a relationship to various submaximal exercise responses. However, due to the narrow range of HbA1c and the limited exercise data from previous studies on individuals with diabetes, little support for the above statement exists in the literature. The current study assessed the relationship between HbA1c and submaximal, or ventilatory threshold (VT), and maximal exercise (VO2 peak) responses in subjects with non-insulin-dependent diabetes mellitus (NIDDM). Sixteen subjects (age = 56.5 +/- 14.4 yrs; Wt = 82.6 +/- 17.2 kg; B.M.I. = 29.5 +/- 2.7 kg.m-2) performed a ramp (20 watts.min-1) leg cycle ergometer test (GXT). Their HbA1c was 11.8 +/- 2.8% (range 6.5 to 16.6%). Breath by breath respiratory analysis was performed using a Med Graphics 2001 cart. Ventilatory threshold (VT) was determined using the V-slope method. The VT was 1,151 +/- 487 ml.min-1 or 70.2 +/- 10% VO2peak; VO2peak was 1,645 +/- 740 ml.min-1. There were no significant relationships found between HbA1c and the VO2 at the VT (r = 0.04), the % of VO2peak at the VT (r = 0.23), and the VO2peak (r = 0.17). In conclusion, metabolic control, as assessed by HbA1c, did not influence selected submaximal and maximal exercise responses in NIDDM. Therefore, exercise prescription for individuals with NIDDM may not need to consider the individual's HbA1c concentration as a modifier of their exercise response.

Adult↗
PubMed1993

Successful weight loss in a self-taught, self-administered program.

There is little evidence concerning the effectiveness of self-help materials for weight control. The purpose of this research was to evaluate a self-help weight-loss program. Obese (body fat > or = 25.0%, range = 25.0-48.6%, mean +/- SEM = 36.5 +/- 1.3%) men (n = 14) and women (n = 21) were given a workbook detailing a behavior modification approach to weight loss that emphasizes self-monitoring of diet and exercise behaviors, and then sent home for 6 months to learn how to lose weight on their own. A group of 9 controls (CONT) who did not get a workbook were used for comparison. ANOVA showed that the experimental group (EXP) lost 8.1 +/- 0.9 (mean +/- SEM) kg body weight, 6.4 +/- 0.8 kg fat, and 3.9 +/- 0.6% body fat; all significant over time (p < 0.001) and different from the CONT (p < 0.0001) who showed no change in these variables. The EXP also reduced their fat intake (% of joules) from 36.1 +/- 1.0% to 27.9 +/- 1.3% (p < 0.0001), increased their carbohydrate intake from 45.7 +/- 1.2% to 50.0 +/- 1.7% (p < 0.007) and their protein intake from 16.3 +/- 0.05% to 20.7 +/- 0.7% (0 < 0.03), all of which were significantly different (p < 0.03) than the CONT who did not change. Dietary fiber increased in the EXP from 19.8 +/- 1.4 to 27.3 +/- 2.2 g/d (p < 0.001) even with a significant reduction in energy intake (11.3 +/- 0.6 vs. 8.9 +/- 0.5 Mj/d; p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effect of exercise on cardiovascular ageing.

Ageing of the cardiovascular system presents several costly public health problems, loss of quality of life, dependency, and other various health hazards. Large declines of 0-24% per decade in cardiovascular function have been cited in the literature but no long-term longitudinal studies have been reported. Serially measured cardiovascular function was performed on 12 normal men, aged 44-79 years, at 0, 10, 15, 20 and 25 years. Over the same time period, daily exercise training data were reported monthly including mode, frequency, intensity, and duration. Although seven men developed some form of pathological disease, the total group's cardiovascular function remained 60% greater than the average of ten investigations. The overall decline in cardiovascular function (Vo2 max) was 13%, or 5% per decade, 45.4 ml.min-1.kg-1 to 39.5 ml.min-1.kg-1. In summary, cardiovascular function was one-half, or 0.24 ml.min-1.kg-1.year-1 of the 0.45 ml.min-1.kg-1.year-1 reported to be the average decline for ageing cited in the literature.

Aged↗
PubMed1993

Predicting max HR and the HR-VO2 relationship for exercise prescription in obesity.

This research derived regression equations for predicting maximal heart rate (MHR) and examined the relationship between relative oxygen consumption (VO2) and heart rate (HR) in obese (N = 86, body fat > 30%, hydrostatic weighing) compared with normal-weight (N = 51, body fat < or = 30%) adults. Simultaneous measurements of HR and VO2 were recorded at rest and every minute during a maximal graded exercise test. When MHR was regressed on age, two distinct equations for the obese and normalweights were generated. The relationship between %MHR and %max VO2 was similar between groups (r = 0.83, obese; r = 0.87 normalweights). Likewise, when %max VO2 was regressed on %max heart rate range similar equations were derived fro the obese (r = 0.81) and normalweights (r = 0.84). Correlation between Karvonen's predicted HR at a submaximal VO2 and the true HR at that VO2 was 0.88, regardless of adiposity. These data indicate that when predicting MHR in normalweights the equation 220-Age can be used, but for obese individuals the equation 200-0.5 x Age is more accurate; each having 12 as a standard error of estimate. Once MHR is determined, either the straight percentage technique or Karvonen's method would be appropriate for prescribing exercise intensity for both populations.

Adipose Tissue↗
PubMed1992

The influence of the fullness of milk in the breasts on the concentration of lactic acid in postexercise breast milk.

The purpose of this study was to observe the influence of the fullness of breast milk in the breasts prior to exercise on the concentration of lactic acid in breast milk following exercise. Twenty-three lactating women were randomly assigned to Group E (n = 11), which nursed and/or collected as much of the breast milk as possible prior to maximal exercise, and Group F (n = 12), which did not nurse or collect milk at least two hours prior to maximal exercise. Milk was collected at rest preexercise and 10, 30, 60 and 90 minutes postexercise and was analyzed for concentrations of lactic acid. ANOVA demonstrated 1) a significant increase in lactic acid in the milk at all postexercise collections for both groups and 2) a significant group vs postexercise time interaction for lactic acid concentration in milk. These differences represented differences in 1) time to peak lactic acid concentrations in milk (Group F = 10 min; Group E = 30 min) and 2) time for postexercise decreases in lactic acid concentrations in milk. Thus, the state of fullness of milk in the breasts is a factor which affects the concentration of lactic acid in breast milk following maximal exercise.

Adult↗
PubMed1992

Infant acceptance of postexercise breast milk.

The purpose of this study was to observe the infant acceptance of postexercise breast milk. Twenty-six lactating postpartum women exercised to maximum (maximum oxygen consumption = 35.1 +/- 9.2 [SD] mL min-1 kg-1) on a treadmill. Breast milk was collected via self-expression at rest before exercise and at 10 and 30 minutes postexercise and analyzed for lactic acid by enzymatic methods. Following exercise, infants were presented with their mothers' pre-exercise and postexercise milk in a double-blind design. The mother rated the infant's acceptance of the milk samples. There was a significant difference in acceptance of pre-exercise and postexercise milk as analyzed by analysis of variance. Maximal exercise resulted in a significant increase in lactic acid concentration in breast milk that may be high enough to affect the taste of the milk. The decreased acceptance of postexercise milk was associated with increased lactic acid concentration. Suggestions to circumvent the decreased acceptance are offered.

Adult↗
PubMed1991

The concentration of lactic acid in breast milk following maximal exercise.

The purpose of this study was to investigate the concentration of lactic acid in breast milk following maximal exercise. Seven active postpartum women (2 to 24 months) were exercised to maximum on a treadmill (VO2 max = 37.0 +/- 13.7 ml.min-1.kg-1). Blood was sampled via finger prick at rest before exercise and 5 minutes postexercise; milk was collected via self expression at rest before exercise and at 10 and 30 minutes postexercise. Both blood and milk were analyzed for lactic acid via enzymatic methods. Following maximal exercise, a significant increase in the concentration of lactic acid was found in the blood at 5 minutes postexercise and breast milk at 10 minutes postexercise. Although elevated, the lactic acid concentration of the 30-minute sample of breast milk was not significantly different from the resting sample. Maximal exercise can result in significant increase in lactic acid concentration in breast milk. Further research is needed to demonstrate whether the taste of the milk is affected.

Breast Feeding↗
PubMed1989

A family approach to cardiovascular risk reduction: results from the San Diego Family Health Project.

The effectiveness of a family-based cardiovascular disease risk reduction intervention was evaluated in two ethnic groups. Participants were 206 healthy, volunteer low-to-middle-income Mexican-American and non-Hispanic white (Anglo-American) families (623 individuals), each with a fifth or a sixth-grade child. Families were recruited through elementary schools. Half of the families were randomized to a year-long educational intervention designed to decrease the whole family's intake of high salt, high fat foods, and to increase their regular physical activity. Eighty-nine percent of the enrolled families were measured at the 24-month follow-up. Both Mexican- and Anglo-American families in the experimental groups gained significantly more knowledge of the skills required to change dietary and exercise habits than did those in the control groups. Experimental families in both ethnic groups reported improved eating habits on a food frequency index. Anglo families reported lower total fat and sodium intake. There were no significant group differences in reported physical activity or in tested cardiovascular fitness levels. Significant differences for Anglo-American experimental vs. control adult subjects were found for LDL cholesterol. Significant intervention-control differences ranging from 2.2 to 3.4 mmHg systolic and/or diastolic blood pressure were found in all subgroups. Direct observation of diet and physical activity behaviors in a structured environment suggested generalization of behavior changes. There was evidence that behavior change persisted one year beyond the completion of the intervention program. It is concluded that involvement of families utilizing school based resources is feasible and effective. Future studies should focus on the most cost-effective methods of family involvement, and the potential for additive effects when family strategies are combined with other school health education programs.

Adolescent↗
PubMed1984

Serum testosterone concentration during two hours of moderate intensity treadmill running in trained men and women.

The purpose of this study was to determine alterations in testosterone concentration in women during 2 hours of moderate intensity running, and to compare this response to that seen in men. Maximal oxygen uptake (VO2 max) and anaerobic threshold (AT) were determined in 11 men and 9 women. These subjects subsequently ran for 2 hours on a motor-driven treadmill at 10% below the AT which was approximately 70% VO2 max. Blood samples were drawn at 0, 30, 60, 90 and 120 minutes of exercise and testosterone was measured by specific radioimmunoassay. Serum testosterone concentration was significantly increased (41%, P less than .01) after 30 minutes of exercise in the men. In the women, testosterone was not significantly increased from pre-exercise concentrations until 120 minutes of exercise (48%, P less than .01). At this time the testosterone concentration in the men had decreased and was no longer significantly elevated from the pre-exercise concentration. The magnitude of the increases in serum testosterone concentration can probably be accounted for by decreases in the metabolic clearance rate of sex-steroids known to occur during exercise. Differences in the testosterone response between men and women during prolonged aerobic exercise are of interest and may imply that different mechanisms of control are involved.

Adolescent↗
PubMed1976

VO2max during horizontal and inclined treadmill running.

The VO2max response of 12 well-trained and highly motivated college males was measured using two treadmill protocols: horizontal (H) and inclined (I). The duration of each test averaged 10 min. In the H test the treadmill bed was horizontal with the running rate held constant for the first 6 min, after which time it was increased at 1-min intervals to near maximal subject running speed, according to the HR response, until exhaustion. The I method simulated the protocol of Costill and Fox, with the treadmill speed at about 80-90% of mean maximal running rate established from 12- and 15-min track runs. The treadmill bed was held horizontal during the first 4 min, after which time it was elevated to 4% and elevated 2% each 2 min thereafter until exhaustion. No significant differences were found in VO2max, 4.267 1/min (I), and 4.192 1/min (H), average max HR, 190.4/MIN (I), and 188.9/min (H); respiratory rate, 56.4/min (I), and 62.0/min (H); and VEBTPS, 145.2 1/min (I), and 143.3 1/min (H). It was concluded that the intensities of both treadmill methods, H and I, were sufficient to produce a nonsignificant difference in maximal VO2 values with the type subjects employed.

Adult↗
PubMed1976

Physiological variables during 10 years of endurance exercise.

The reported decline in Physical Working Capacity (PWC) max is from 9-15 percent during the ages of 45 to 55 years. The use of vigorous physical activity to prevent this decline and to possibly protect against fatal myocardial infarction has been suggested. The purpose of this study was to investigate the effect of an endurance type exercise program on the maximal PWC of middle-aged men during a 10 year span. Sixteen men, initially 32-56 years (M-44.6), were trained with running or swimming at an intensity above 60 percent of VO2 max during a 10 year period. The average weekly running distance was 15 miles (25 km). The criterion for PWC was directly measured VO2 using the Douglas Bag/Scholander technique. No changes were observed in body weight, resting heart rate (HR), or resting blood pressure (BP). Maximal HR declined 7 beats per minute in 10 years. Pulmonary ventilation (STPD) increased approximately 18 percent. Mean VO2 max was essentially unchanged, 3.376 and 3.303 1/min STPD. VO2 max related to body weight was 43.7 initially and 44.4 ml/min-kg after 10 years. It was concluded that the usual 9-15 percent decline in PWC or VO2 max from age 45 to 55 years can be forestalled by regular endurance exercise. The results may have implications for protecting against heart attacks.

Adult↗
PubMedDate not supplied

Effects of diet and exercise interventions on control and quality of life in non-insulin-dependent diabetes mellitus.

Evidence suggests that diet and exercise are associated with improved glucose tolerance for patients with non-insulin-dependent diabetes mellitus (NIDDM). Seventy-six volunteer adult patients with NIDDM were each assigned to one of four programs: diet, exercise, diet plus exercise, or education (control). Each program required ten weekly meetings. Detailed evaluations were completed prior to the program and after three, six, 12, and 18 months. Evaluations included various psychosocial measures, measures of the quality of life, and fasting blood glucose, glycosylated hemoglobin, and relative weight determinations. Of the 76 original participants, 70 completed the 18-month follow-up study. At 18 months, the combination diet-and-exercise group had achieved the greatest reductions in glycosylated hemoglobin measures. In addition, this group showed significant improvements on a general quality of life measure. These improvements were largely uncorrelated with changes in weight. The authors conclude that the combination of dietary change and physical conditioning benefits NIDDM patients, and that the benefits may be independent of substantial weight loss.

Activities of Daily Living↗