George A. Kelley

Exercise and Hypertension

Hypertension (HTN), one of the most common medical disorders, is associated with an increased incidence of all-cause and cardiovascular disease (CVD) mortality. Lifestyle modifications are advocated for the prevention, treatment, and control of HTN, with exercise being an integral component. Exercise programs that primarily involve endurance activities prevent the development of HTN and lower blood pressure (BP) in adults with normal BP and those with HTN. The BP lowering effects of exercise are most pronounced in people with HTN who engage in endurance exercise with BP decreasing approximately 5-7 mm HG after an isolated exercise session (acute) or following exercise training (chronic). Moreover, BP is reduced for up to 22 h after an endurance exercise bout (e.g.postexercise hypotension), with greatest decreases among those with highest baseline BP. The proposed mechanisms for the BP lowering effects of exercise include neurohumoral, vascular, and structural adaptations. Decreases in catecholamines and total peripheral resistance, improved insulin sensitivity, and alterations in vasodilators and vasoconstrictors are some of the postulated explanations for the antihypertensive effects of exercise. Emerging data suggest genetic links to the BP reductions associated with acute and chronic exercise. Nonetheless, definitive conclusions regarding the mechanisms for the BP reductions following endurance exercise cannot be made at this time. Individuals with controlled HTN and no CVD or renal complications may participated in an exercise program or competitive athletics, but should be evaluated, treated and monitored closely. Preliminary peak or symptom-limited exercise testing may be warranted, especially for men over 45 and women over 55 yr planning a vigorous exercise program (i.e. > or = 60% VO2R, oxygen uptake reserve). In the interim, while formal evaluation and management are taking place, it is reasonable for the majority of patients to begin moderate intensity exercise (40-<60% VO2R) such as walking. When pharmacological therapy is indicated in physically active people it should be, ideally: a) lower BP at rest and during exertion; b) decrease total peripheral resistance; and, c) not adversely affect exercise capacity. For these reasons, angiotensin converting enzyme (ACE) inhibitors (or angiotensin II receptor blockers in case of ACE inhibitor intolerance) and calcium channel blockers are currently the drugs of choice for recreational exercisers and athletes who have HTN. Exercise remains a cornerstone therapy for the primary prevention, treatment, and control of HTN. The optimal training frequency, intensity, time, and type (FITT) need to be better defined to optimize the BP lowering capacities of exercise, particularly in children, women, older adults, and certain ethnic groups. based upon the current evidence, the following exercise prescription is recommended for those with high BP: Frequency: on most, preferably all, days of the week. Intensity: moderate-intensity (40-<60% VO2R). Time: > or = 30 min of continuous or accumulated physical activity per day. Type: primarily endurance physical activity supplemented by resistance exercise.

Progressive Resistance Exercise and Resting Blood Pressure: A Meta-Analysis of Randomized Controlled Trials

Hypertension is a major public health problem affecting an estimated 43 million civilian, noninstitutionalized adults in the United States (24% of this population). The purpose of this study was to use the meta-analytic approach to examine the effects of progressive resistance exercise on resting systolic and diastolic blood pressure in adult humans. Studies were retrieved via (1) computerized literature searches, (2) cross-referencing from original and review articles, and (3) review of the reference list by 2 experts on exercise and blood pressure. Inclusion criteria were as follows: (1) trials that included a randomized nonexercise control group; (2) progressive resistance exercise as the only intervention; (3) adult humans; (4) journal articles, dissertations, and masters theses published in the English-language literature; (5) studies published and indexed between January 1966 and December 1998; (6) resting systolic and/or diastolic blood pressure assessed; and (7) training studies lasting a minimum of 4 weeks. Across all designs and categories, fixed-effects modeling yielded decreases of approximately 2% and 4% for resting systolic and diastolic blood pressure, respectively (mean+/-SD systolic, -3+/-3 mm Hg; 95% bootstrap CI, -4 to -1 mm Hg; mean+/-SD diastolic, -3+/-2 mm Hg; 95% bootstrap CI, -4 to -1 mm Hg). It was concluded that progressive resistance exercise is efficacious for reducing resting systolic and diastolic blood pressure in adults. However, a need exists for additional studies that limit enrollment to hypertensive subjects as well as analysis of data with an intention-to-treat approach before the effectiveness of progressive resistance exercise as a nonpharmacological intervention can be determined.

Impact of progressive resistance training on lipids and lipoproteins in adults: a meta-analysis of randomized controlled trials.

OBJECTIVE Given the discrepant findings of progressive resistance training (PRT) on lipids and lipoproteins in adults, we used the meta-analytic approach to examine this issue. METHODS Randomized controlled trials > or =4 weeks dealing with the effects of PRT on lipids and lipoproteins in adult humans > or =18 years of age and published between January 1, 1955 and July 12, 2007 were included. Primary outcomes included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), ratio of total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). A random-effects model was used for analysis with data reported as means and 95% confidence intervals. RESULTS Twenty-nine studies representing 1329 men and women (676 exercise, 653 control) were included. Statistically significant improvements were found for TC (-5.5 mg/dl, -9.4 to -1.6), TC/HDL-C (-0.5, -0.9 to -0.2), non-HDL-C (-8.7 mg/dl, -14.1 to -3.3), LDL-C (-6.1 mg/dl, -11.2 to -1.0) and TG (-8.1 mg/dl, -14.5 to -1.8) but not HDL-C (0.7 mg/dl, -1.2 to 2.6). Changes were equivalent to -2.7%, 1.4%, -11.6%, -5.6%, -4.6%, and -6.4%, respectively, for TC, HDL-C, TC/HDL-C, non-HDL-C, LDL-C, and TG. CONCLUSIONS Progressive resistance training reduces TC, TC/HDL-C, non-HDL-C, LDL-C and TG in adults.

Resistance training and bone mineral density in women: a meta-analysis of controlled trials.

Kelley GA, Kelley KS, Tran ZV: Resistance training and bone mineral density in women: a meta-analysis of controlled trials. Am J Phys Med Rehabil 2001;80:65–77. The purpose of this study was to use meta-analysis to examine the effects of resistance training on bone mineral density at the femur, lumbar spine, and radius in pre- and postmenopausal women. Resistance training had a positive effect on bone mineral density at the lumbar spine of all women and at the femur and radius sites for postmenopausal women. It was concluded that resistance training has a positive effect on bone mineral density in women.

Exercise and regional bone mineral density in postmenopausal women : A meta-analytic review of randomized trials

By using the meta-analytic approach, the purpose of this study was to examine the effects of exercise on regional bone mineral density in postmenopausal women. A total of 11 randomized trials yielding 40 outcome measures and a total of 719 subjects (370 exercise, 349 nonexercise) met the criteria for inclusion: (1) randomized trials; (2) exercise as a primary intervention in postmenopausal women; (3) changes in regional bone mineral density reported; (4) comparative nonexercise group included; (5) studies published in English-language journals between January 1975 and December 1995. Across all designs and categories, treatment effect changes in bone density, weighted by sample size, ranged from -17.10 to 17.30% (mean, 0.27%; 95% confidence interval, 0.16-0.37%). When analyzed separately, sample weighted decreases of approximately -0.51 and -0.86% were found for exercise and nonexercise groups, respectively. Larger effects were observed when groups that did not measure bone density specific to the site loaded and groups that received some type of supplementation (calcium or hormone replacement therapy) were deleted from the model (mean change, 0.76%; 95% confidence interval, 0.6-0.93). Both aerobic and strength training enhanced regional bone mineral density (mean change: aerobic, 1.62% and 95% confidence interval, 1.12-2.12; strength, 0.65% and 95% confidence interval, 0.48-0.83). In conclusion, meta-analytic review of included studies suggests that exercise may slow the rate of bone loss in postmenopausal women. However, it is premature to form strong conclusions regarding the effects of exercise on regional bone mineral density in postmenopausal women. A need exists for additional, well designed studies on this topic before a recommendation can be made regarding the efficacy of exercise as a nonpharmacologic therapy for maintaining and/or increasing regional bone mineral density in postmenopausal women.

Effects of community-deliverable exercise on pain and physical function in adults with arthritis and other rheumatic diseases: a meta-analysis.

To use the meta‐analytic approach to determine the effects of community‐deliverable exercise on pain and physical function in adults with arthritis and other rheumatic diseases (AORD).

Aerobic exercise and lipids and lipoproteins in patients with cardiovascular disease : a meta-analysis of randomized controlled trials

PURPOSE Use the meta-analytic approach to examine the effects of aerobic exercise on lipids and lipoproteins in adults with cardiovascular disease (CVD). METHODS Studies were retrieved via electronic databases, review of reference lists from retrieved articles, including reviews, and hand searching. Inclusion criteria were: (1) randomized controlled trials, (2) aerobic exercise >or=4 weeks as an intervention, (3) studies published in English language only between January 1, 1955 and January 1, 2005, (4) studies published in journals or as dissertations or masters theses, (5) human subjects >or=18 years, (6) all subjects diagnosed with some type of CVD, and (7) pre and post data available for total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and/or triglycerides (TG). Random-effects models were used for data analysis. RESULTS Of the more than 3,000 studies reviewed, a total of 10 representing 1,260 subjects (580 exercise, 680 control) were included in our analysis. There was a statistically significant increase of 9% in HDL-C (mean +/- SEM, 3.7 +/- 1.3 mg/dL; 95% CI, 1.2 to 6.1 mg/dL) and a statistically significant decrease of 11% in TG (-19.3 +/- 5.4 mg/dL; 95% CI, -30.1 to -8.5 mg/dL), but no statistically significant decreases in TC or LDL-C (TC, -8.8 +/- 6.8 mg/dL; 95% CI, -22.3 to 4.7 mg/dL; LDL-C, -7.7 +/- 6.0 mg/dL; 95% CI, -19.5 to 4.2 mg/dL). CONCLUSIONS The present findings suggest that chronic aerobic exercise increases HDL-C and decreases TG in adults, especially men, with CVD.

Aerobic Exercise and Lumbar Spine Bone Mineral Density in Postmenopausal Women: A Meta-Analysis

PURPOSE: To use the meta‐analytic approach to examine the effects of aerobic exercise on lumbar spine bone mineral density in postmenopausal women.

Comparison of aerobic exercise, diet or both on lipids and lipoproteins in adults: a meta-analysis of randomized controlled trials.

OBJECTIVE Given that previous studies have reached conflicting conclusions regarding the effects of diet (D), aerobic exercise (E) or both (DE) on blood lipid and lipoprotein concentrations in adults, the meta-analytic approach was used to address this issue. DATA SOURCES Nine electronic databases, cross-referencing, and expert review. STUDY SELECTION Randomized controlled trials ≥ 4 weeks that included a D, E, DE and control (C) group in adults ≥ 18 years of age and in which data for one or more of the following were available: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG). DATA EXTRACTION Dual data extraction by the first two authors. STATISTICAL ANALYSIS Random-effects models as well as mixed-effects models for between-group differences. RESULTS Seven-hundred and eighty-eight men and women from 6 studies were included. Non-overlapping 95% confidence intervals were observed for D and DE with respect to lowering TC, LDL-C and TG while reductions in E were limited to TG. No significant changes in HDL-C were observed. When compared to E, reductions in TC and LDL-C were greater for D and DE (p < 0.05 for all). CONCLUSIONS Diet, especially DE, are superior to E for improving selected lipids and lipoproteins in adults.

Efficacy of Resistance Exercise on Lumbar Spine and Femoral Neck Bone Mineral Density in Premenopausal Women: A Meta-Analysis of Individual Patient Data

BACKGROUND Osteoporosis and osteopenia are major public health problems. The purpose of this study was to conduct an individual patient data (IPD) meta-analysis to examine the efficacy of resistance exercise on lumbar spine and femoral neck bone mineral density (BMD) in premenopausal women. METHODS Studies were retrieved via (1). computerized literature searches, (2). review of reference lists from previous studies, (3). hand searching selected journals, and (4). expert review of the reference list. Two x two analysis of covariance (ANCOVA) tests with repeated measures on one factor (time) and study as a covariate were used to analyze changes in BMD. RESULTS One hundred forty-three subjects (74 exercise, 69 control) were included in the analysis. Changes in lumbar spine BMD averaged 0.006 +/- 0.035 g/cm(2) (0.64 +/- 2.99%) in the exercise group and 0.008 +/- 0.091 g/cm(2) (0.74 +/- 7.58%) in the control group, and changes in femoral neck BMD averaged 0.005 +/- 0.031 g/cm(2) (0.46 +/- 3.10%) in the exercise group and 0.003 +/- 0.031 g/cm(2) (0.31 +/- 2.97%) in the control group. No statistically significant differences in lumbar spine or femoral neck BMD were found within or between the exercise and control groups (p > 0.05). CONCLUSIONS Based on existing evidence, our results do not support the efficacy of resistance exercise for increasing or maintaining lumbar spine and femoral neck BMD in premenopausal women.