The influence of acute exercise on bone biomarkers: protocol for a systematic review with meta-analysis.

BACKGROUND: Bone is a plastic tissue that is responsive to its physical environment. As a result, exercise interventions represent a potential means to influence the bone. However, little is currently known about how various exercise and participant characteristics interact to influence bone metabolism. Acute, controlled, interventions provide an in vivo model through which the acute bone response to exercise can be investigated, typically by monitoring circulating bone biomarkers. Currently, substantial heterogeneity in factors such as study design, quality, exercise, and participant characteristics render it difficult to synthesize and evaluate the available evidence. Using a systematic review and meta-analytic approach, the aim of this investigation is to quantify the effect of an acute exercise bout on circulating bone biomarkers as well as examine the potential factors that may moderate this response, e.g., variation in participant, exercise, and sampling characteristics. METHODS: This protocol was designed in accordance with the PRISMA-P guidelines. Seven databases (MEDLINE, Embase, Sport Discus, Cochrane CENTRAL, PEDro, LILACS, and Ibec) will be systematically searched and supplemented by a secondary screening of the reference lists of all included articles. The PICOS (Population, Intervention, Comparator, Outcomes and Study Design) approach was used to guide the determination of the eligibility criteria. Participants of any age, sex, training, or health status will be considered for inclusion. We will select studies that have measured the bone biomarker response before and after an acute exercise session. All biomarkers considered to represent the bone metabolism will be considered for inclusion, and sensitivity analyses will be conducted using reference biomarkers for the measurement of bone resorption and formation (namely ß-CTX-1 and P1NP). Multi-level, meta-regression models within a Bayesian framework will be used to explore the main effect of acute exercise on bone biomarkers as well as potential moderating factors. The risk of bias for each individual study will be evaluated using a modified version of the Downs and Black checklist while certainty in resultant outcomes will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. DISCUSSION: A better understanding of the bone metabolic response to an acute bout of exercise has the potential to advance our understanding of the mechanisms through which this stimulus impacts bone metabolism, including factors that may moderate this response. Additionally, we will identify current gaps in the evidence base and provide recommendations to inform future research. SYSTEMATIC REVIEW REGISTRATION: This protocol was prospectively registered in the Open Science Framework Registry ( https://osf.io/6f8dz ).

Exercise and bone mineral density in men: a meta-analysis of randomized controlled trials.

OBJECTIVE: Use the meta-analytic approach to examine the effects of ground and/or joint reaction force exercise on femoral neck (FN) and lumbar spine (LS) bone mineral density (BMD) in men. METHODS: Randomized controlled exercise trials ≥ 24 weeks were included. Standardized effect sizes (g) were calculated and pooled using random-effects models, z-score alpha values and 95% confidence intervals (CI). Heterogeneity was examined using Q and I(2). Statistical significance was set at a two-tailed alpha value (p) of ≤ 0.05 and a trend at >0.05 to ≤ 0.10. RESULTS: A moderate and statistically significant improvement was found at the FN (3 g's, 187 participants, g=0.583, 95% CI=0.031, 1.135, p=0.04, Q=5.6, p=0.06, I(2)=64%) while a small trend was observed at the LS (5 g's, 275 participants, g=0.190, 95% CI=-0.036, 0.416, p=0.10, Q=3.0, p=0.55, I(2)=0%). Results were sensitive to influence analysis as well as collapsing multiple groups from the same studies so that only one g represented each study. CONCLUSIONS: There is currently insufficient evidence to recommend ground and/or joint reaction force exercise for improving and/or maintaining FN and LS BMD in men. Additional well-designed randomized controlled trials are needed before any final recommendations can be formulated.

Exercise improves global well-being in adults with fibromyalgia: confirmation of previous meta-analytic results using a recently developed and novel varying coefficient model.

OBJECTIVES: To determine the effects of exercise (aerobic, strength training or both) on global well-being in adults with fibromyalgia (FM). METHODS: The meta-analytic approach and recently developed varying coefficient model were used to pool the results of previous randomised controlled trials of exercise (aerobic, strength training or both) on global well-being in adults with FM. The standardised effect size (ES) for global well-being from each study was pooled using a recently developed and novel varying coefficient (VC) model and partitioned according to per-protocol and intention-to-treat analyses. Results were also compared to the traditionally used random effects (RE) model. Non-overlapping 95% confidence intervals were considered statistically significant with negative ESs indicative of improvements in global well-being. RESULTS: Five ESs representing 377 participants were included in the per-protocol analysis and 5 ESs representing 252 participants were included in the intention-to-treat analysis. Using the VC model, statistically significant improvements in global-well being were found for both per-protocol (-X, -0.39, 95% CI, -0.62, -0.15) and intention-to-treat analysis (-X, -0.40, 95% CI, -0.68, -0.13). Results were similar to those from the RE model. CONCLUSIONS: Using the recently developed and more valid varying coefficient model, these findings confirm that exercise improves global-well being in adults with FM.

Effects of aerobic exercise on lipids and lipoproteins in adults with type 2 diabetes: a meta-analysis of randomized-controlled trials.

OBJECTIVE: To conduct a meta-analysis of randomized-controlled trials in order to examine the effects of 8 weeks or more of aerobic exercise on lipids and lipoproteins in adults with Type 2 diabetes. METHODS: Studies were included if total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), ratio of TC to HDL-C (TC/HDL-C), triglycerides (TG), or all of the above, were assessed. A secondary outcome was glycosylated haemoglobin (HbA1). RESULTS: Seven studies representing 220 men and women (112 exercise, 108 control) were available for pooling. Using a random-effects model, a statistically significant reduction of about 5% was found for LDL-C, whereas no statistically significant improvements were found for TC, HDL-C, TC/HDL-C or TG. A trend for a statistically significant reduction in HbA1 was also found. CONCLUSIONS: Although our overall results suggest that aerobic exercise lowers LDL-C in adults with Type 2 diabetes, additional randomized-controlled trials are needed on this topic.

Aerobic exercise, lipids and lipoproteins in overweight and obese adults: a meta-analysis of randomized controlled trials.

OBJECTIVE: Use the meta-analytic approach to examine the effects of aerobic exercise on lipids and lipoproteins in overweight and obese adults. DATA SOURCES: (1) Computerized literature searches, (2) cross-referencing from review and original articles, (3) hand searching, and (4) expert review of reference list. STUDY SELECTION: (1) randomized controlled trials, (2) aerobic exercise > or =8 weeks, (3) adult humans > or =18 y of age, (4) all subjects overweight or obese (BMI > or =25 kg/m(2)), (5) studies published in journal, dissertation, or master's thesis format, (6) studies published in the English-language, (7) studies published between 1 January 1955 and 1 January 2003, (8) assessment of one or more of the following lipid and/or lipoprotein variables: total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG). DATA ABSTRACTION: Dual-coding by the first two authors (inter-rater agreement=0.96). RESULTS: In total, 13 studies representing 31 groups (17 exercise, 14 control), 613 subjects (348 exercise, 265 control), and up to 17 outcomes were available for pooling. Across all categories, random-effects modeling resulted in statistically significant improvements for TC (X +/- s.e.m., - 3.4+/-1.7 mg/dl, 95% CI, - 6.7 to - 0.2 mg/dl) and TG (X +/-s.e.m., - 16.1+/-7.3 mg/dl, 95% CI, - 30.2 to - 2.1 mg/dl) but not HDL (X +/- s.e.m., 1.6+/-0.8 mg/dl, 95% CI, - 0.02 to 3.2 mg/dl) or LDL (X +/-s.e.m., - 0.5+/-1.3 mg/dl, 95% CI, - 3.0 to 2.0 mg/dl). Changes were equivalent to improvements of 2% (TC), 11% (TG), 3% (HDL), and 0.3% (LDL). After conducting sensitivity analyses (each study deleted from the model once), only decreases in TG remained statistically significant. Increases in HDL were associated with increases in maximum oxygen consumption (VO(2 max) in ml/kg/min, r=0.75, P=0.002) and decreases in body weight (r=0.77, P<0.001), while decreases in LDL were associated with decreases in body weight (r=0.75, P=0.009). CONCLUSIONS: Aerobic exercise decreases TG in overweight and obese adults. However, a need exists for additional randomized controlled trials in various overweight and/or obese populations above and beyond those included in our analysis.

Walking and resting blood pressure in adults: a meta-analysis.

BACKGROUND: The purpose of this study was to examine the effects of walking on resting systolic and diastolic blood pressure in adults. METHODS: A total of 24 primary outcomes from 16 studies and 650 subjects (410 exercise, 240 control) met the criteria for inclusion: (1) randomized and nonrandomized controlled trials, (2) walking as the only intervention, (3) subjects apparently sedentary, (4) adult humans > or =18 years of age, (5) English-language studies published between January 1966 and December 1998, (6) resting blood pressure assessed, (7) training studies > or =4 weeks. RESULTS: Using a random effects model, statistically significant decreases of approximately 2% were found for both resting systolic and diastolic blood pressure (systolic, mean +/- SEM = -3 +/- 1 mm Hg, 95% confidence interval: -5 to -2 mm Hg; diastolic, mean +/- SEM = -2 +/- 1 mm Hg, 95% confidence interval: -3 to -1 mm Hg). CONCLUSION: Walking exercise programs reduce resting blood pressure in adults.

Aerobic exercise and resting blood pressure in older adults: a meta-analytic review of randomized controlled trials.

BACKGROUND: It is well established that resting systolic and diastolic blood pressure (SBP and DBP, respectively) increases as one ages. This study used the meta-analytic approach to examine the effects of aerobic exercise for reducing resting SBP and DBP in older adults. METHODS: Study data were compiled through use of the following: (i) computer searches (MEDLINE, Current Contents, and Sport Discus), (ii) cross-referencing from bibliographies of retrieved studies and review articles, and (iii) an expert who reviewed our reference list. Inclusion criteria and sources for this study were (i) randomized trials, (ii) aerobic activity as the only exercise intervention, (iii) a nonexercise control group, (iv) an assessment of changes in resting SBP and/or DBP, (v) within-study ages of subjects > or = 50 years, (vi) English-language studies published in journals, and (vii) studies published between January 1966 and January 1998. Net changes in resting BP were calculated as the exercise minus control group difference. RESULTS: Fourteen primary outcomes were derived from seven studies. Decreases of approximately 2% and 1% were found for resting SBP and DBP, with only changes in SBP as statistically significant (SBP, mean +/- SD = -2 +/- 3 mm Hg, 95% confidence interval [CI] = -4 to -1 mm Hg; DBP, mean +/- SD = -1 +/- 2 mm Hg, 95% CI = -2 to 0 mm Hg). CONCLUSIONS: This study supports the efficacy of aerobic exercise for reducing resting SBP in older adults. However, a need exists for studies that address the effectiveness of this intervention for reducing resting BP in older adults.

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

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.

Original metric vs. standardized effect sizes for meta-analysis of clinical data.

This study compared the use of the original metric effect size with the standardized effect size for clinical data in meta-analysis. The example data set included 17 controlled clinical trials dealing with the effects of progressive resistance exercise on resting diastolic blood pressure in adults. Original metric effect size showed a decrease in resting diastolic blood pressure of -2.07 mm Hg (95% confidence interval, -3.60 to -0.54). From a clinical standpoint, this is considered a "small" effect. The standardized approach showed an average effect of -0.21, 95% CI= -0.39 to -0.02. This is also considered a "smal" effect. When possible, use of the original metric is preferred because it can be more clinically meaningful and will enhance interpretation of blood pressure results for a wider range of readers. (c) 2001 by CHF, Inc

Aerobic exercise and resting blood pressure: a meta-analytic review of randomized, controlled trials.

In this study the authors used the meta-analytic approach to examine the effects of aerobic exercise on resting systolic and diastolic blood pressure in adults. Forty-seven clinical trials representing a total of 72 effect sizes in 2543 subjects (1653 exercise, 890 control) met the criteria for inclusion. Statistically significant exercise-minus-control decreases were found for changes in resting systolic and diastolic blood pressure in both hypertensive (systolic, -6 mm Hg, 95% CI, -8 to -3; diastolic, -5 mm Hg, 95% CI, -7 to -3) and normotensive (systolic, -2 mm Hg, 95% CI, -3 to -1; diastolic, -1 mm Hg, 95% CI, -2 to -1) groups. The differences between groups were statistically significant (systolic, p=0.008; diastolic, p=0.000). Relative decreases were approximately 4% (systolic) and 5% (diastolic) in hypertensives, and 2% (systolic) and 1% (diastolic) in normotensives. It was concluded that aerobic exercise reduces resting systolic and diastolic blood pressure in adults. (c) 2001 by CHF, Inc.

Exercise and bone mineral density in men: a meta-analysis.

The purpose of this study was to use the meta-analytic approach to examine the effects of exercise on bone mineral density (BMD) in men. A total of 26 effect sizes (ES) representing 225 subjects from 8 studies met the criteria for inclusion. When BMD sites assessed were specific to the sites loaded during exercise, increases of approximately 2.6% (2.1% in the exercisers and -0.5% in the controls) were found. These results were statistically significant (ES = 0.213, 95% bootstrap confidence interval = 0.007-0.452). Statistically significant ES changes were found for older (>31 yr) but not younger (<31 yr) adults, with differences between groups statistically significant (P = 0.04). Statistically significant changes were also observed at the femur, lumbar, and os calcis sites. The results of this study suggest that site-specific exercise may help improve and maintain BMD at the femur, lumbar, and os calcis sites in older men. However, the biological importance of the small changes observed for most outcomes, quality of studies, and limited data pool prevent us from forming any firm conclusion regarding the use of exercise for maintaining and/or improving BMD in men. Clearly, a need exists for additional studies.

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.

Aerobic exercise and resting blood pressure in women: a meta-analytic review of controlled clinical trials.

The purpose of this study was to use the meta-analytic approach to examine the effects of aerobic exercise on resting systolic and diastolic blood pressure in women. Twenty-one studies representing 1029 subjects (663 exercise, 366 controls) and 54 primary outcomes (28 systolic, 26 diastolic) met the criteria for inclusion. Across all designs and categories, statistically significant decreases in resting systolic (mean +/- SD, -2.03 +/- 2.87, 95% confidence interval [CI] -3.14 to -0.92 mm Hg) but not diastolic (mean +/- SD, -0.64 +/- 2.02, 95% CI -1.45 to 0.18 mm Hg) blood pressure were found. Changes in resting systolic blood pressure were correlated with initial systolic blood pressure, initial body mass index, initial resting heart rate, and rest period before assessment of blood pressure. Meta-analysis of included studies suggests that aerobic exercise causes small reductions in resting systolic blood pressure in women. However, a need exists for additional, well-designed studies on this topic, especially among hypertensive adult women.

Aerobic exercise and resting blood pressure among women: a meta-analysis.

PURPOSE: The aim of this study was to use the meta-analytic approach to examine the effects of aerobic exercise on resting systolic and diastolic blood pressure among adult women. METHODS: Studies were retrieved from computer searches (MEDLINE, Sport Discus, Current Contents) and bibliographies of retrieved articles were cross-referenced. Inclusion criteria were as follows: (1) randomized trials, (2) aerobic activity as the primary exercise intervention, (3) comparative nonexercise control group included, (4) changes in resting systolic and/or diastolic blood pressure assessed for women ages 18 and older, and (5) studies published in English-language journals between January 1966 and January 1998. The primary outcomes retrieved in this study were changes in resting systolic and diastolic blood pressure calculated as the difference (exercise minus control) of the changes (initial minus final) in these mean values. RESULTS: Ten studies representing 732 subjects and 36 primary outcomes (19 systolic, 17 diastolic) met the criteria for inclusion. Overall, an approximate 2% decrease in resting systolic and 1% decrease in resting diastolic blood pressure were observed (systolic,;x +/- SD = -2 +/- 2.6 mm Hg, 95% bootstrap confidence interval -3 to -1 mm Hg; diastolic,;x +/- SD = -1 +/- 1.9 mm Hg, 95% bootstrap confidence interval -2 to -1 mm Hg). CONCLUSION: Aerobic exercise results in small reductions in resting systolic and diastolic blood pressure among adult women. However, a need exists for additional, well-designed studies on this topic, especially among hypertensive adult women.

Gender differences in the aerobic fitness levels of young African-American adults.

This study examines gender differences in the aerobic fitness levels of young African-American adults. Two hundred twelve African-American college freshmen (79 men, 133 women) completed the Houston Non-Exercise Test-Body Mass Index Model (HNET-BMI) questionnaire, a questionnaire designed to estimate maximum oxygen consumption (VO2max, mL kg-1 min-1) in adults. Using a three-point scoring system (below average, average, and above average), 100% of the men and 80% of the women were classified as having average or above average levels of VO2max. Statistical analysis revealed that more women than men had average or below average levels of aerobic fitness (chi 2 = 54.5; P = .0001). The results of this study suggest that a larger percentage of African-American women have lower levels of aerobic fitness compared with African-American men.

Psychological readiness of black college students to be physically active.

Black students' psychological readiness to be physically active was examined in 212 1st-year students (79 men and 133 women) at a historically Black university in the South. The students responded to the Physician-based Assessment and Counseling for Exercise (PACE) survey, which asked students about current physical activity habits. More men (57%) than women (32%) were classified as being in the action stage. Approximately 37% of the men in the sample, compared with 63% of the women, were in the contemplation stage, and 6% of the men and 5% of the women were classified as precontemplators. The findings indicated that health professionals need to provide interventions aimed at increasing the physical activity of Black students, especially 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.

Aerobic exercise and bone density at the hip in postmenopausal women: a meta-analysis.

BACKGROUND: The effects of aerobic exercise on bone density at the hip in postmenopausal women in the absence of estrogen replacement therapy are not currently known. The purpose of this study was to examine the effects of aerobic exercise on bone density at the hip in postmenopausal women. METHODS: Using the meta-analytic approach, studies dealing with the effects of aerobic exercise on bone density at the hip in postmenopausal women were searched for using computerized literature searches (MEDLINE, January 1978 to December 1995) as well as cross-referencing from retrieved review articles and original investigations. RESULTS: A total of 18 effect sizes were derived from six studies. Using a fixed-effects model and bootstrap resampling (5,000 iterations) overall changes in bone density at the hip yielded an average effect size of 0.43 (95% CI = 0.04 to 0.81), equivalent to an overall change of approximately 2.42% (exercise = 2.13%; nonexercise = -0.29%). Statistically significant differences were observed when effect sizes were partitioned by country in which studies were conducted (United States, mean = 1.03, 95% CI = 0.48 to 1.68; other countries, mean = 0.18, 95% CI = -0.27 to 0.54; Qb = 5.44, P = 0.04) and calcium intake (> or =1,000 mg/day, mean = 0.83, 95% CI = 0.49 to 1.23; <1,000 mg/day = -0.23, 95% CI = -0.85 to 0.21; Qb = 10.64, P = 0.002). CONCLUSIONS: The overall results of this study suggest that site-specific aerobic exercise has a moderately positive effect on bone density at the hip in postmenopausal women. However, a need exists for additional, well-designed studies before a final recommendation can be made regarding the efficacy of aerobic exercise as a nonpharmacologic intervention for optimizing bone density at the hip in postmenopausal women.

Cardiovascular disease risk factors in black college students.

Selected cardiovascular disease risk factors in 238 Black 1st-year college students (89 men and 149 women) were examined. Students responded to a health risk survey asking about their blood pressure and cholesterol levels as well as their smoking and physical activity habits. Approximately 2% of the men and 3% of the women reported having high blood pressure. Forty-three percent of the men and 48% of the women had never had their cholesterol level checked or could not remember the result of the test. Only 6% of the men and 5% of the women reported that they smoked cigarettes. More women (62%) than men (38%) engaged in vigorous physical activity fewer than three times per week. The results indicated that health professionals need to increase awareness of blood cholesterol levels among Black men and women and should focus intervention efforts on increasing the physical activity levels of Blacks, especially women.

Gender differences in the physical activity levels of young African-American adults.

This study examines gender differences in the physical activity levels of young African-American adults. One hundred twenty-seven African-American college freshmen (57 males and 70 females) completed the Lipid Research Clinic's Physical Activity questionnaire. Using a four-point scoring method (ie, very low active, low active, moderately active, and high active), approximately 71% of females compared with 49% of males were classified as very low active or low active. Statistical analysis revealed significant gender differences between groups. Post hoc analysis revealed that the difference existed in the high-activity category for females, with few females being categorized as high active. The results of this study suggest that young African-American adult females are less active than their male counterparts.