Biomedical subjects

Guoyuan Huang

Publications and source records attributed to Guoyuan Huang.

6 recordsLinked to original sources

PubMed2006

Author contacts for retrieval of data for a meta-analysis on exercise and diet restriction.

OBJECTIVES: The mode of contact and response levels of authors who had been asked to provide missing or incomplete data for a systematic review on diet and exercise interventions for weight loss was examined. METHODS: We contacted authors by electronic mail, letter, or both. Survival analyses were performed with the Kaplan-Meier method to determine differences in the proportion of responders over time among the different modes of contact and to determine whether response rates differed between authors from the United States and those from other countries. Logistic regression was used to determine whether the number of items requested and publication date influenced the likelihood of response. RESULTS: Two hundred forty-one (39.9 percent) studies had missing or incomplete data (e.g., sample size, age, caloric restriction, exercise amount, and so on). We were unable to locate ninety-five authors (39.4 percent). Of the remaining authors, forty-six authors (31.5 percent) responded to information requests. Time to respond differed by contact method (p < .05): e-mail (3 +/- 3 days), letter (27 +/- 30 days), and both (13 +/-12 days). Response rates from U.S. authors did not differ from those of other countries. CONCLUSIONS: Our study suggests poor success in the acquisition of essential information. Given considerable time and resources, weight loss studies require improved reporting standards to minimize the relatively unsuccessful attempt to contact authors for important and necessary information.

Clinical Trials as Topic↗

PubMed2005

Reporting quality of randomized trials in the diet and exercise literature for weight loss.

BACKGROUND: To adequately assess individual studies and synthesize quantitative research on weight loss studies, transparent reporting of data is required. The authors examined the reporting quality of randomized trials in the weight loss literature, focusing exclusively on subject characteristics as they relate to enrollment, allocation, and follow-up. METHODS: An extensive literature review, which included a computerized search of the MEDLINE database, manual searches of bibliographic references, and cross-referencing of 92 review articles was conducted. A checklist, based on CONSORT recommendations, was used to collect information on whether or not authors reported age, gender, co-morbid disease, medication use, race/ethnicity, and postmenopausal status. Also tracked was whether or not initial and final sample size was reported and stratified by gender. RESULTS: Of 604 possible articles, 231 articles met eligibility criteria. Important subject characteristics were not reported as the following breakdown indicates: age (11%), gender (4%), race/ethnicity (86%), co-morbid disease states (34%), and medication use (92%). Additionally, 21% of articles failed to report initial sample size by gender while 69% neglected to report final sample size by gender. CONCLUSION: Inadequate reporting can create difficulties with interpretation and can lead to biased results receiving false credibility. The quality of reporting for weight loss studies needs considerable improvement.

Demography↗

PubMed2005

Controlled endurance exercise training and VO2max changes in older adults: a meta-analysis.

This meta-analysis of controlled clinical trials quantifies the effect of aerobic exercise on VO2max (aerobic fitness) among sedentary older adults and examines the associations of such magnitude with variables of intervention. Forty-one trials including 2102 older subjects (within-group mean age of 60 years and older) were identified by searches of databases, hand searching, and cross-referencing. Outcomes were homogeneous. The pooled standardized effect size by a fixed-effect model showed a higher moderate effect (mean +/- SEM) of 0.64+/-0.05; 95% confidence interval, 0.56-0.73; p<0.001, representing a net increase in VO2max (mean +/- SEM) of 3.78+/-0.28 mL.kg-1.min-1; 95% confidence interval, 3.24-4.33; or a 16.3% improvement, compared with control groups. Greater improvement in VO2max was associated with training length more than 20 weeks and training intensity of approximately 60% but less than 70% of VO2max. Endurance training improves aerobic fitness in older adults, thus providing protective benefits for cardiovascular aging and quality of later life.

Exercise↗

PubMed2005

Resting heart rate changes after endurance training in older adults: a meta-analysis.

PURPOSE: Question remains regarding endurance training and changes in resting heart rate (HR) among older individuals. The objective of this meta-analysis was to determine the effects of controlled aerobic training on resting HR among sedentary older adults. METHODS: Studies were identified by a systematic computer database search, hand article search, and cross-reference. The inclusion criteria were (i) controlled clinical trials, (ii) endurance exercise as the only intervention, (iii) a nonexercise control group, (iv) within-group mean ages of subjects > or = 60 yr, (v) a measure of changes in resting HR, (vi) studies published in English journals. RESULTS: Outcome was derived from 13 studies with a total of 651 individuals in 14 control (N = 241) and 16 exercise groups (N = 410). The pooled standardized effect size by a fixed-effect model showed an upper moderate effect of -0.58 +/- 0.08 (mean +/- SEM, 95% CI = -0.74 to -0.42). This homogeneity effect was statistically significant (P = 0.001). The magnitude of net change averaged -6 bpm (-2 to -12 bpm), representing an 8.4% reduction. Greater and statistically significant decrease of resting HR among the elderly was found in the studies with training length more than 30 wk. CONCLUSIONS: This meta-analytic investigation supports the efficacy of endurance exercise training in decreasing HR at rest in older adults. This training induced adaptation may have protective benefits for cardiovascular aging. A longer exercise training length, probably more than 30 wk, may be needed for older individuals to be more effective in terms of resting HR reduction.

Electrocardiography↗

PubMed2005

Changes in pulmonary function response to a 10-week controlled exercise program in sedentary elderly adults.

This randomized clinical trial was aimed to assess whether pulmonary function would change in sedentary elderly people after a controlled exercise program. 45 participants over 75 yr. of age (M age 83.7 +/- 3.0) were assigned randomly to a control and two aerobic exercise groups of moderate and high intensity. In 10 wk. the program sessions were 40 min. in duration 3 days per week. Forced vital capacity (FVC) and forced expiratory volume in 1 sec. (FEV1.0) were measured pre- and post-intervention. After the training, the Moderate intensity group experienced significant mean change in FVC. In the High intensity group, significant changes were observed in both FVC and FEV1.0, but no change was noted for the Control group. The 10-wk. aerobic training of moderate or high intensity showed positive effects on pulmonary function in these elderly individuals. These exercise-induced changes may be dose-related.

Aged↗

PubMedDate not supplied

Aging and arterial blood pressure variability during orthostatic challenge.

BACKGROUND: It has been demonstrated that a decrease in vagal cardiac function compromises arterial blood pressure (ABP) stability during orthostatic challenge. Augmentations in low-frequency (LF) ABP oscillations are indicative of this change in autonomic hemodynamic control. Aging is associated with diminished arterial baroreflex sensitivity and vagal cardiac dysfunction. However, the effect of aging on the stability of ABP during an orthostatic challenge remains to be elucidated. OBJECTIVE: The purpose of this study was to investigate ABP stability with aging during central hypovolemia induced by lower-body negative pressure (LBNP). METHODS: Graded LBNP up to -40 mm Hg was applied in 16 older (65 +/- 3 years of age) and 16 younger (25 +/- 3 years of age) healthy adults. ABP variability was analyzed by fast Fourier transform. LF spectral density (0.04-0.15 Hz) was extracted to provide an index of vasomotor responsiveness. RESULTS: Both LF systolic blood pressure (SBP) variability and diastolic blood pressure variability were augmented with LBNP. The rate of increase in LF SBP variability was augmented significantly greater in older as compared with younger subjects (p = 0.049). In addition, LF SBP variability was inversely correlated with decreases in pulse pressure in both age groups (r = -0.84, p = 0.01). The magnitude of the decreases in SBP and pulse pressure during LBNP was significantly affected by age, with the largest changes occurring in older subjects. The altered ABP response that manifested in older individuals was associated with a significant diminution in the reflex tachycardiac response elicited by LBNP. CONCLUSIONS: Induction of central hypovolemia via graded LBNP augments LF ABP variability. This increased ABP variability is significantly greater in older individuals. Our data suggest that aging is associated with ABP instability during orthostatic challenge.

Adult↗