Biomedical subjects

Patty S Freedson

Publications and source records attributed to Patty S Freedson.

11 recordsLinked to original sources

PubMed2004

Effects of a single bout of exercise on resting heart rate variability.

PURPOSE: Chronic exercise training has been shown to have a positive influence on cardiac autonomic function as assessed by measures of heart rate variability (HRV). Recent evidence indicates that several benefits associated with exercise training (e.g., improved insulin action, reduced blood pressure, improved blood lipid profile) may be realized transiently after a single bout of exercise. As many of these effects of recent exercise are linked to cardiovascular control systems, the purpose of this investigation was to test the hypothesis that a single bout of exercise would result in favorable changes in cardiac autonomic function as assessed by frequency-domain measures of HRV. METHODS: Subjects were 11 healthy male volunteers ages 18-35 yr. Resting HRV measures were obtained during 5 min of paced breathing before and 1, 3, 6, and 22 h after a 60-min bout of cycling exercise at approximately 65% of peak oxygen uptake. Identical measures were obtained in a nonexercise condition based on a randomized crossover design. RESULTS: Exercise resulted in increased high-frequency HRV, decreased low-frequency HRV, and consequently a decrease in the ratio of low-frequency to high-frequency HRV compared with the nonexercise condition. Additionally, a time-domain measure of HRV (pNN50) was markedly higher in the exercise condition as compared to nonexercise. CONCLUSION: The changes in cardiac autonomic function observed are similar to those seen in investigations of long-term training. These changes indicate a shift in autonomic function toward increased parasympathetic nervous system activity and decreased sympathetic nervous system activity, suggesting a more stable autonomic environment for the heart. These results may provide further evidence of the cardioprotective effects of a single bout of submaximal exercise.

Adolescent↗

PubMed2004

Development and validation of a Pregnancy Physical Activity Questionnaire.

PURPOSE: The effect of physical activity during pregnancy on maternal and fetal health remains controversial and studies have yet to identify the optimal dose of physical activity associated with favorable pregnancy outcomes. The aim of this study was to develop and validate a pregnancy physical activity questionnaire (PPAQ). METHODS: To ascertain the type, duration, and frequency of physical activities performed by pregnant women, three 24-h physical activity recalls were administered to 235 ethnically diverse prenatal care patients at a large tertiary care facility in western Massachusetts. The relative contribution of each activity to between-person variance in energy expenditure was used to establish the list of activities for the PPAQ. The PPAQ is self-administered and asks respondents to report the time spent participating in 32 activities including household/caregiving, occupational, sports/exercise, transportation, and inactivity. To validate the PPAQ, 54 pregnant women completed the PPAQ and then wore a Manufacturing Technology, Inc. actigraph for the following 7 d. At the end of the 7-d period, the PPAQ was repeated. RESULTS: Intraclass correlation coefficients used to measure reproducibility of the PPAQ were 0.78 for total activity, 0.82 for moderate activity, 0.81 for vigorous activity, and ranged from 0.83 for sports/exercise to 0.93 for occupational activity. Spearman correlations between the PPAQ and three published cut points used to classify actigraph data ranged from 0.08 to 0.43 for total activity, 0.25 to 0.34 for vigorous activity, 0.20 to 0.49 for moderate activity, and -0.08 to 0.22 for light-intensity activity. Correlations were higher for sports/exercise and occupational activities as compared to household/caregiving activities. CONCLUSIONS: household/caregiving activities. CONCLUSIONS: The PPAQ is a reliable instrument of physical activities during pregnancy.

Adolescent↗

PubMed2003

Evaluating a model of parental influence on youth physical activity.

OBJECTIVE: To test a conceptual model linking parental physical activity orientations, parental support for physical activity, and children's self-efficacy perceptions with physical activity participation. PARTICIPANTS AND SETTING: The sample consisted of 380 students in grades 7 through 12 (mean age, 14.0+/-1.6 years) and their parents. Data collection took place during the fall of 1996. MAIN OUTCOME MEASURES: Parents completed a questionnaire assessing their physical activity habits, enjoyment of physical activity, beliefs regarding the importance of physical activity, and supportive behaviors for their child's physical activity. Students completed a 46-item inventory assessing physical activity during the previous 7 days and a 5-item physical activity self-efficacy scale. The model was tested via observed variable path analysis using structural equation modeling techniques (AMOS 4.0). RESULTS: An initial model, in which parent physical activity orientations predicted child physical activity via parental support and child self-efficacy, did not provide an acceptable fit to the data. Inclusion of a direct path from parental support to child physical activity and deletion of a nonsignificant path from parental physical activity to child physical activity significantly improved model fit. Standardized path coefficients for the revised model ranged from 0.17 to 0.24, and all were significant at the p<0.0001 level. CONCLUSIONS: Parental support was an important correlate of youth physical activity, acting directly or indirectly through its influence on self-efficacy. Physical activity interventions targeted at youth should include and evaluate the efficacy of individual-level and community-level strategies to increase parents' capacity to provide instrumental and motivational support for their children's physical activity.

Adolescent↗

PubMed2003

Body mass index, but not physical activity, is associated with C-reactive protein.

UNLABELLED: Elevated high-sensitivity c-reactive protein (hs-CRP) is associated with increased risk of future first and recurrent coronary events and has been associated with both high body mass index (BMI) and low physical activity in cross sectional studies. PURPOSE: To longitudinally examine the effects of BMI and both current and previous-year physical activity on hs-CRP in healthy men and women (N = 109). METHODS: BMI and hs-CRP were measured five times (baseline and quarterly) over 1 yr. Current physical activity was assessed 12-15 times during the study via 24-h recall. Previous-year physical activity was assessed using the Baecke questionnaire at baseline. RESULTS: Mean BMI and hs-CRP were unchanged over the course of the study, but current physical activity increased on visit 3. Average hs-CRP was not related to average current physical activity or to natural changes in current physical activity across the five visits. Additionally, current physical activity on any given visit was not associated with hs-CRP on the following visit. When current physical activity, BMI, age, gender, and smoking were included in the statistical model, only BMI was significantly related to hs-CRP (P < 0.001). Average hs-CRP was significantly correlated with average BMI (r = 0.50; P < 0.001) but was not related to previous-year (Baecke) physical activity levels (r = 0.02; P = 0.89). When subjects were grouped by BMI (<25 kg.m-2, 25-29.9 kg x m-2, >30 kg x m-2) hs-CRP was significantly greater in obese (3.2 +/- 1.9 mg.L-1) and overweight (2.1 +/- 1.7 mg x L-1) than normal weight (1.1 +/- 1.0 mg.L-1) subjects (ANOVA P < 0.05). Current physical activity was similar between the three BMI groups at all times, and was unrelated to hs-CRP in all groups, throughout the study period. CONCLUSION: These data indicate that BMI, but not previous-year or current physical activity, predicts hs-CRP.

Adult↗

PubMed2003

Estimating physical activity using the CSA accelerometer and a physical activity log.

PURPOSE: To compare two methods for measuring time spent in physical activity of differing absolute intensities. METHODS: Over a 7-d period, 59 women wore Computer Science and Applications, Inc. (CSA) accelerometers and recorded their activity in physical activity logs (PAL) at 15-min intervals. Three published cut points were used to classify CSA data into resting/light, moderate, and vigorous intensity categories. Data were analyzed using descriptive statistics, Spearman rank-order correlations, and Bland-Altman plots. RESULTS: The CSA estimates of total (moderate plus vigorous) physical activity using the three cut points ranged from a mean (+/- SD) of 38.1 (+/-26.8) min.d-1 to 312.6 (+/- 101.1) min.d-1. Using the PAL, women self-reported a mean (+/- SD) of 75.1 (+/- 51.7) min.d-1 of total activity. There was fair to modest rank-order agreement between each of the three CSA measures and the PAL measure of total activity, with correlations ranging from r = 0.15 to 0.24. Correlations between CSA and PAL estimates of total activity were higher in women with body mass index values (BMI) below 25 kg.m-2 (r = 0.23-0.38) compared with women with BMI > or = 25 kg.m-2 (r = 0.06-0.08) but did not differ according to age. Correlations between the three CSA cut points ranged from r = 0.45 to 0.86. CONCLUSIONS: Three published cut points designed to classify CSA output by intensity level produced different estimates of physical activity participation. Correlations between CSA and PAL measures of activity intensity were fair overall but higher among leaner women.

Adult↗

PubMed2002

Reproducibility of a self-administered lifetime physical activity questionnaire among female college alumnae.

Recent epidemiologic evidence suggests that lifetime physical activity is an important factor in the development of many chronic diseases. The authors assessed the reproducibility of a self-administered physical activity questionnaire designed to assess the duration, frequency, and intensity of lifetime household and recreational activities. The study was conducted among 134 female college alumnae from two colleges in western Massachusetts who were aged 39-65 years in 1998. A modified version of the Historical Leisure Activity Questionnaire was used to assess physical activity over four prior age periods (menarche to 21 years and 22-34, 35-50, and 51-65 years). The questionnaire was administered to participants by mail twice 1 year apart. The intraclass correlation coefficients used to measure reproducibility were 0.82 for total lifetime physical activity, 0.80 for lifetime moderate-intensity activities, 0.86 for lifetime vigorous-intensity activities, 0.87 for lifetime recreational activities, and 0.78 for lifetime household activities. Correlations were 0.73 for total activity during the earliest prior age period (menarche to 21 years), 0.70 for ages 22-34 years, 0.78 for ages 35-50 years, and 0.83 for ages 51-65 years. These data indicate that this physical activity questionnaire is reproducible and provides a useful measure of average lifetime activity.

Adult↗

PubMed2002

Compliance with physical activity guidelines: prevalence in a population of children and youth.

PURPOSE: To use objective monitoring of physical activity to determine the percentages of children and youth in a population that met physical activity guidelines. METHODS: A total of 375 students in grades 1-12 wore an accelerometer (CSA 7164) for seven consecutive days. Bouts of continuous activity and accumulation of minutes spent in physical activity at various intensities were calculated to determine how many students met three physical activity guidelines. RESULTS: Over 90% of students met Healthy People 2010, Objective 22.6 and nearly 70% met the United Kingdom Expert Consensus Group guideline, both of which recommend daily accumulation of moderate physical activity. Less than 3% met Healthy People 2010, Objective 22.7, which calls for bouts of continuous vigorous physical activity. For the United Kingdom Expert Consensus Group guideline, compliance decreased markedly with age, but gender differences were not statistically significant. CONCLUSIONS: Prevalence estimates for compliance with national physical activity guidelines varied markedly for the three guidelines examined. Objective monitoring of physical activity in youth appears to be feasible and may provide more accurate prevalence rates than self-report measures.

Activities of Daily Living↗

PubMed2002

Age and gender differences in objectively measured physical activity in youth.

PURPOSE: The purpose of this study was to evaluate age and gender differences in objectively measured physical activity (PA) in a population-based sample of students in grades 1-12. METHODS: Participants (185 male, 190 female) wore a CSA 7164 accelerometer for 7 consecutive days. To examine age-related trends, students were grouped as follows: grades 1-3 (N = 90), grades 4-6 (N = 91), grades 7-9 (N = 96), and grades 10-12 (N = 92). Bouts of PA and minutes spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) were examined. RESULTS: Daily MVPA and VPA exhibited a significant inverse relationship with grade level, with the largest differences occurring between grades 1-3 and 4-6. Boys were more active than girls; however, for overall PA, the magnitudes of the gender differences were modest. Participation in continuous 20-min bouts of PA was low to nonexistent. CONCLUSION: Our results support the notion that PA declines rapidly during childhood and adolescence and that accelerometers are feasible alternatives to self-report methods in moderately sized population-level surveillance studies.

Activities of Daily Living↗

PubMed2002

Validity and reproducibility of a physical activity questionnaire in women.

PURPOSE: To determine the validity and reproducibility of a self-administered physical activity questionnaire that assesses the frequency, intensity, and duration of recreational, household, and occupational activity in women. METHODS: The questionnaire was administered by mail twice to 131 participants 1 yr apart. During this interval, participants completed four 1-wk activity logs corresponding to different seasons throughout the year. RESULTS: The intraclass correlation coefficients used to measure reproducibility were 0.82 for total activity, 0.79 for moderate activity, 0.86 for vigorous activity, 0.80 for recreational activity, and 0.73 for household activity. The distribution of activity scores was similar between the questionnaires and the average of the four logs, indicating the participants' ability to incorporate seasonal variation into their recall on a questionnaire. The correlations between the questionnaire-based activity scores and log-based activity scores, indicating validity, were 0.26 for total activity, 0.15 for moderate activity, and 0.52 for vigorous activity. Women younger than age 50 tended to have higher validity scores than women aged 50 yr and older (r = 0.31 vs r = 0.19, respectively, for total activity). CONCLUSION: These data indicate that this physical activity questionnaire is reproducible and provides a useful measure of current activity, particularly vigorous activity, over a 1-yr period.

Adult↗

PubMed2002

Moderate to vigorous physical activity and risk of upper-respiratory tract infection.

PURPOSE: A "J"-shaped model has been proposed to describe the relationship between physical activity and risk of upper-respiratory tract infection (URTI). However, little epidemiologic evidence is available to support the contention that moderately active individuals are at lowest risk of URTI. This investigation examined differences in URTI risk between physically inactive and moderately active adults. METHODS: Observational study of 547 healthy adults (49% women) aged 20-70 yr reported URTI events at 90-d intervals over 12-month of follow-up (5 evaluations). Three 24-h physical activity recalls per evaluation were obtained and averaged to quantify total moderate-vigorous activity (> or =3.0 metabolic equivalents [MET]). Associations between URTI and physical activity levels were estimated using incidence rate ratios (IRR) derived using Poisson regression while adjusting for a number of potential confounders including age, education, anxiety, cynicism, and selected dietary factors. RESULTS: Men and women reported 1.2 (1.4) and 1.2 (1.2) URTI events per year, respectively (mean [(SD]). Adjusting for gender and potential confounders, the IRR for less than 3.93, 3.94-7.15, 7.16-11.95, and > or = 11.96 MET-h.d(-1) among men, and less than 2.38, 2.39-4.09, 4.10-6.24, and > or = 6.25 MET-h.d(-1) among women, were 1.00 (referent), 0.87 (95% confidence interval [CI], 0.70-1.07), 0.88 (95% CI, 0.71-1.09), and 0.77 (95% CI, 0.62-0.95), respectively (P(trend) = 0.03). This effect was stronger in men (P(trend) = 0.03) than women (P(trend) = 0.17), although at similar expenditure levels (6-7 MET-h.d-1), risk was reduced by about 20% in men and women. Risk reduction was most pronounced in the fall of the year (P(trend) = 0.02). CONCLUSIONS: These data support the hypothesis that moderate levels of physical activity are associated with a reduced risk for URTI.

Adult↗

PubMed2002

Development and validation of a one-mile treadmill walk test to predict peak oxygen uptake in healthy adults ages 40 to 79 years.

The purpose of this investigation was to determine whether the Rockport one-mile walk test equation to predict maximal oxygen uptake was valid for application to treadmill walking. When the Rockport model was found to be inappropriate, a new regression model was developed for predicting peak oxygen uptake (VO2peak) from a one-mile treadmill walk. 304 healthy volunteers ages 40 to 79 years (mean age = 57.6 years, 154 men and 150 women) completed a VO2peak test and a one-mile treadmill walk. Stepwise regression was used to build a model for the relationship between VO2peak and a variety of predictor variables in a sub-sample development group (n = 154). This new model was then applied to a sub-sample validation group (n = 150). The new equation produced a correlation of 0.87, SEE = 4.7 ml x kg (-1) x min (-1) with a mean residual of 0.96 ml x kg (-1) x min (-1). The equation for predicting VO2peak developed in this investigation provides a means of assessing VO2peak that is easy to administer, allows for careful supervision of subjects, and can be completed at a low financial and temporal cost.

Adult↗