Guoyuan Huang

Dose-response relationship of cardiorespiratory fitness adaptation to controlled endurance training in sedentary older adults.

Background The purpose of this investigation was to identify a quantitative dose–response relationship for enhancing maximal oxygen consumption (VO2max) in healthy sedentary older adults after controlled endurance training. Methods and results This meta-analysis of controlled clinical trials included 1257 exercisers and 845 controls with a mean age of 67.45 ± 5.25 years. Effect sizes were calculated for training-induced VO2max changes. Different training regimens were analyzed and compared. The weighted net change of the mean VO2max values showed a significant increase of 3.78 ml/kg per min (95% confidence interval = 3.29 to 4.27; p < 0.0001) in response to aerobic training. Interstudy differences in VO2max changes were significantly related to exercise intensity, and explained approximately 11% of the variance of the VO2max responses. VO2max improved significantly at 35%–50% heart rate reserve (HRR) and continued improving at a greater rate with increasing “dose”. The largest VO2max-improvement adaptation was achieved with a mean intensity of 66%–73% HRR. The magnitudes of the VO2max adaptation are identical to exercise at 57%–65% HRR and at 75%–80% HRR. Higher intensity doses more than 75–80% HRR did not lead to greater enhancement of VO2max improvements but, conversely, resulted in large declines. Conclusions Our data provide quantitative insight into the magnitude of VO2max alterations as affected by exercise intensity, duration, frequency, and program length. The shapes of the dose–response curves are not simply linear, but with many similar trends and noteworthy characteristics. Aerobic training at a mean intensity of 66%–73% HRR with 40–50 min per session for 3–4 day/week for 30–40 weeks appears to be effective and optimal for maximum cardiorespiratory benefits in healthy sedentary older adults.

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

BackgroundTo 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.MethodsAn 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.ResultsOf 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.ConclusionInadequate 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.

Cerebral vasoreactivity during hypercapnia is reset by augmented sympathetic influence

Sympathetic nerve activity influences cerebral blood flow, but it is unknown whether augmented sympathetic nerve activity resets cerebral vasoreactivity to hypercapnia. This study tested the hypothesis that cerebral vasodilation during hypercapnia is restrained by lower-body negative pressure (LBNP)-stimulated sympathoexcitation. Cerebral hemodynamic responses were assessed in nine healthy volunteers [age 25 yr (SD 3)] during rebreathing-induced increases in partial pressure of end-tidal CO(2) (Pet(CO(2))) at rest and during LBNP. Cerebral hemodynamic responses were determined by changes in flow velocity of middle cerebral artery (MCAV) using transcranial Doppler sonography and in regional cerebral tissue oxygenation (ScO(2)) using near-infrared spectroscopy. Pet(CO(2)) values during rebreathing were similarly increased from 41.9 to 56.5 mmHg at rest and from 40.7 to 56.0 mmHg during LBNP of -15 Torr. However, the rates of increases in MCAV and in ScO(2) per unit increase in Pet(CO(2)) (i.e., the slopes of MCAV/Pet(CO(2)) and ScO(2)/Pet(CO(2))) were significantly (P ≤0.05) decreased from 2.62 ± 0.16 cm·s(-1)·mmHg(-1) and 0.89 ± 0.10%/mmHg at rest to 1.68 ± 0.18 cm·s(-1)·mmHg(-1) and 0.63 ± 0.07%/mmHg during LBNP. In conclusion, the sensitivity of cerebral vasoreactivity to hypercapnia, in terms of the rate of increases in MCAV and in ScO(2), is diminished by LBNP-stimulated sympathoexcitation.

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.

Controlled aerobic exercise training reduces resting blood pressure in sedentary older adults

Abstract The results of existing controlled clinical trials were synthesized to determine effects of aerobic exercise training on resting systolic (SBP) and diastolic blood pressure (DBP) among previously sedentary older adults, to quantify the magnitude of observed changes, and to examine the influence of the associated interventional variables on these changes. Studies were identified via a systematic computer database search, hand searching, and cross-referencing of previously located articles. All potentially eligible articles were carefully reviewed and examined with the established inclusion criteria. Twenty-three studies, representing a total of 1226 older subjects, were included in the final analysis. Robust statistically significant effects were found in terms of the pooled standardized effect size of − 0.33 ± 0.06 (p < 0.0001) in SBP and − 0.39 ± 0.09 (p < 0.0001) in DBP. When compared with the control group, net decreases in both SBP (− 5.39 ± 1.21 mmHg, p < 0.0001) and DBP (−3.68 ± 0.83 mmHg, p < 0.0001) were observed in older exercisers, representing a 3.9% and a 4.5% reduction, respectively. This meta-analytic study provides robust quantitative data to support the efficacy and effectiveness of controlled endurance exercise training in decreasing resting SBP and DBP among previously sedentary older adults.

Habitual aerobic exercise, gene APOA5 named rs662799 SNP and response of blood lipid and lipoprotein phenotypes among older Chinese adult

Background: The genetic component of dyslipidemia has been studied in adults but little in older population. It is remains unknown regarding influence and interaction of APOA5 gene single nucleotide polymorphism (SNP) and habitual aerobic exercise (HAE) on changes of blood lipids and lipoprotein phenotypes in older Chinese adults. Methods: Four‐hundred‐twenty‐three old Chinese individuals with HAE were divided into hyperlipidemia and normal groups. We genotyped polymorphic loci using matrix assisted laser desorption ionization time of flight mass spectrometry detection technology (MALDI–TOF). HAE level was assessed by International Physical Activity Questionnaire (IPAQ) scale. Results: For three genotypes of rs662799 site, the AG + GG gene carriers presented higher risk of hyperlipidemia compared to the AA carriers, with the ratio of 1.676 (P = .018, 95% CI: 1.092–2.571) for the AG and 1.812 (P = .002, 95% CI: 1.247–2.632) for the GG, respectively. The rs662799 G allele was significantly associated with lower HDL‐C but higher TG levels. In relation to different HAE levels, less interaction was observed between the AA carriers and different HAE levels on corresponding lipids changes. The AG + GG carriers with higher HAE levels had significantly lower TG responses compared to those with lower HAE levels (1.45 ± 0.74 mmol/L vs. 1.86 ± 1.15 mmol/L). Conclusions: Excess risk for low HDL‐C and hyperlipidemia was associated with rs662799 genotype alleles of APOA5 SNPs in older Chinese adults. Interaction of gene‐HAE and HAE levels may induce different responses of blood lipids and lipoprotein phenotypes. HAE levels have less influence on TG changes in the AA carriers; however, high HAE levels appeared to greatly impact TG responses in the AG + GG carriers. Highlightsrs662799 SNP impact blood lipidHAE less impact TG in AA carriersHAE impact TG in AG+GG carriers