Michael J. LaMonte

Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise

SUMMARYThe purpose of this Position Stand is to provide guidance to professionals who counsel and prescribe individualized exercise to apparently healthy adults of all ages. These recommendations also may apply to adults with certain chronic diseases or disabilities, when appropriately evaluated and

Cardiorespiratory Fitness Is Inversely Associated With the Incidence of Metabolic Syndrome A Prospective Study of Men and Women

Background—Few studies have reported the relationship between cardiorespiratory fitness and metabolic syndrome incidence, particularly in women. Methods and Results—We prospectively studied 9007 men (mean±SD age, 44±9 years; body mass index, 25±3 kg/m2) and 1491 women (age, 44±9 years; body mass index, 22±2 kg/m2) who were free of metabolic syndrome and for whom measures of waist girth, resting blood pressure, fasting lipids, and glucose were taken during baseline and follow-up examinations. Baseline cardiorespiratory fitness was quantified as duration of a maximal treadmill test. Metabolic syndrome was defined with NCEP ATP-III criteria. During a mean follow-up of 5.7 years, 1346 men and 56 women developed metabolic syndrome. Age-adjusted incidence rates were significantly lower (linear trend, P<0.001) across incremental thirds of fitness in men and women. After further adjustment for potential confounders, multivariable hazard ratios for incident metabolic syndrome among men in the low, middle, and upper thirds of fitness, were 1.0 (referent), 0.74 (95% CI, 0.65 to 0.84), and 0.47 (95% CI, 0.40 to 0.54) (linear trend P<0.001); in women, they were 1.0 (referent), 0.80 (95% CI, 0.44 to 1.46), and 0.37 (95% CI, 0.18 to 0.80) (linear trend P=0.01), respectively. Similar patterns of significant inverse associations between fitness and metabolic syndrome incidence were seen when men were stratified on categories of body mass index, age, and number of baseline metabolic risk factors, but patterns were variable in women. Conclusions—Low cardiorespiratory fitness is a strong and independent predictor of incident metabolic syndrome in women and men. Clinicians should consider the potential benefits of greater cardiorespiratory fitness in the primary prevention of metabolic syndrome, particularly among patients who have already begun to cluster metabolic syndrome components.

Associations of muscle strength and fitness with metabolic syndrome in men

PURPOSE To examine the associations for muscular strength and cardiorespiratory fitness with the prevalence of metabolic syndrome among men. METHODS Participants were 8570 men (20-75 yr) for whom an age-specific muscular strength score was computed by combining the body weight adjusted one-repetition maximum measures for the leg press and the bench press. Cardiorespiratory fitness was quantified by age-specific maximal treadmill exercise test time. RESULTS Separate age and smoking adjusted logistic regression models revealed a graded inverse association for metabolic syndrome prevalence with muscular strength (beta = -0.37, P < 0.0001) and cardiorespiratory fitness (beta = -1.2, P < 0.0001). The association between strength and metabolic syndrome was attenuated (beta = -0.08, P < 0.01) when further adjusted for cardiorespiratory fitness. The association between cardiorespiratory fitness and metabolic syndrome was unchanged (beta = -1.2, P < 0.0001) after adjusting for strength. Muscular strength added to the protective effect of fitness among men with low (P trend = 0.0002) and moderate (P trend < 0.0001) fitness levels. Among normal weight (BMI < 25), overweight (BMI 25-30), and obese (BMI >or= 30) men, respectively, being strong and fit was associated with lower odds (73%, 69%, and 62% respectively, P < 0.0001) of having prevalent metabolic syndrome. CONCLUSIONS Muscular strength and cardiorespiratory fitness have independent and joint inverse associations with metabolic syndrome prevalence.

Quantifying energy expenditure and physical activity in the context of dose response.

PURPOSE Methods for assessing physical activity (PA) and energy expenditure (EE) were reviewed to identify potential limitations to evaluating and interpreting dose-response relationships between PA and health-related outcomes and to suggest future research directions in this area. METHODS Literature describing PA and EE assessment methodology was reviewed according to the reported validity, reliability, and feasibility of the measurement in epidemiologic studies. A summary of this review is presented for techniques applicable to studying PA or EE among free-living individuals. RESULTS Several methods with varying degrees of precision and feasibility have been used to assess PA and EE in free-living populations. Lack of a gold standard field measure of PA may explain some of the variability in precision among these methods. The most accurate field measure of EE appears to be doubly labeled water; however, this approach has limited feasibility in terms of cost and use in studies of total EE only. Electronic motion sensors and physiologic measures related with EE are limited in their ability to discriminate specific types of PA and by inconvenient measurement procedures. Self-reported PA records and surveys are low-cost, relatively unobtrusive methods of assessing PA and EE in field settings and vary in terms of their format, mode of administration, and degree of detailing habitual PA levels. Disparity in the metric used to quantify PA and EE exists within the current literature, which limits the interpretation and comparison of observed dose-response relationships. CONCLUSIONS Efforts to develop equated methods of assessing PA and EE in free-living populations are needed before a systematic evaluation and interpretation of dose-response characteristics between PA and specific health-related parameters can be undertaken.

Cardiorespiratory Fitness Levels Among US Adults 20–49 Years of Age: Findings From the 1999–2004 National Health and Nutrition Examination Survey

Data from the 1999-2004 National Health and Nutrition Examination Survey were used to describe the distribution of cardiorespiratory fitness and its association with obesity and leisure-time physical activity (LTPA) for adults 20-49 years of age without physical limitations or indications of cardiovascular disease. A sample of 7,437 adults aged 20-49 years were examined at a mobile examination center. Of 4,860 eligible for a submaximal treadmill test, 3,250 completed the test and were included in the analysis. The mean maximal oxygen uptake ( max) was estimated as 44.5, 42.8, and 42.2 mL/kg/minute for men 20-29, 30-39, and 40-49 years of age, respectively. For women, it was 36.5, 35.4, and 34.4 mL/kg/minute for the corresponding age groups. Non-Hispanic black women had lower fitness levels than did non-Hispanic white and Mexican-American women. Regardless of gender or race/ethnicity, people who were obese had a significantly lower estimated maximal oxygen uptake than did nonobese adults. Furthermore, a positive association between fitness level and LTPA participation was observed for both men and women. These results can be used to track future population assessments and to evaluate interventions. The differences in fitness status among population subgroups and by obesity status or LTPA can also be used to develop health policies and targeted educational campaigns.

Physical activity, cardiorespiratory fitness, and adiposity: contributions to disease risk

Purpose of reviewTo discuss assessing physical activity, cardiorespiratory fitness, and adiposity in the context of examining their prospective joint associations with mortality in cohort studies. Recent findingsAccurate and comprehensive assessment of free-living physical activity patterns and related energy expenditure is difficult. Cardiorespiratory fitness is a reproducible measure associated with recent physical activity patterns; however, its assessment has been considered impractical in epidemiologic studies. Likewise, objective measures of adiposity and fat distribution often are not feasible in large studies. Thus, physical activity and adiposity exposures typically are quantified using self-reports of physical activity habits and of height and weight to compute body mass index. When considered jointly, adults with higher levels of fitness or reported physical activity tend to have lower mortality risk than their unfit and inactive peers within the same body mass index group. SummaryAccumulating evidence suggests that higher physical activity or fitness attenuates the health risks of obesity. Available data largely are based on crude measures of physical activity and body habitus, which may obscure their association with disease risk. Accurate measures must be included in epidemiologic studies to improve estimation of the independent and joint associations of these exposures with health outcomes.

Association Between Annual Visit-to-Visit Blood Pressure Variability and Stroke in Postmenopausal Women Data From the Women's Health Initiative

Accumulating evidence suggests that increased visit-to-visit variability (VVV) of blood pressure is associated with stroke. No study has examined the association between VVV of blood pressure and stroke in postmenopausal women, and scarce data exist as to whether this relation is independent of the temporal trend of blood pressure. We examined the association of VVV of blood pressure with stroke in 58228 postmenopausal women enrolled in the Womens Health Initiative. Duplicate blood pressure readings, which were averaged, were taken at baseline and at each annual visit. VVV was defined as the SD for the participants mean systolic blood pressure (SBP) across visits (SD) and about the participants regression line with SBP regressed across visits (SDreg). Over a median follow-up of 5.4 years, 997 strokes occurred. In an adjusted model including mean SBP over time, the hazard ratios (95% CI) of stroke for higher quartiles of SD of SBP compared with the lowest quartile (referent) were 1.39 (1.03–1.89) for quartile 2, 1.52 (1.13–2.03) for quartile 3, and 1.72 (1.28–2.32) for quartile 4 (P trend <0.001). The relation was similar for SDreg of SBP quartiles in a model that additionally adjusted for the temporal trend in SBP (P trend <0.001). The associations did not differ by stroke type (ischemic versus hemorrhagic). There was a significant interaction between mean SBP and SDreg on stroke with the strongest association seen below 120 mmHg. In postmenopausal women, greater VVV of SBP was associated with increased risk of stroke, particularly in the lowest range of mean SBP.

Health outcomes of gastric bypass patients compared to nonsurgical, nonintervened severely obese

Favorable health outcomes at 2 years postbariatric surgery have been reported. With exception of the Swedish Obesity Subjects (SOS) study, these studies have been surgical case series, comparison of surgery types, or surgery patients compared to subjects enrolled in planned nonsurgical intervention. This study measured gastric bypass effectiveness when compared to two separate severely obese groups not participating in designed weight‐loss intervention. Three groups of severely obese subjects (N = 1,156, BMI ≥ 35 kg/m2) were studied: gastric bypass subjects (n = 420), subjects seeking gastric bypass but did not have surgery (n = 415), and population‐based subjects not seeking surgery (n = 321). Participants were studied at baseline and 2 years. Quantitative outcome measures as well as prevalence, incidence, and resolution rates of categorical health outcome variables were determined. All quantitative variables (BMI, blood pressure, lipids, diabetes‐related variables, resting metabolic rate (RMR), sleep apnea, and health‐related quality of life) improved significantly in the gastric bypass group compared with each comparative group (all P < 0.0001, except for diastolic blood pressure and the short form (SF‐36) health survey mental component score at P < 0.01). Diabetes, dyslipidemia, and hypertension resolved much more frequently in the gastric bypass group than in the comparative groups (all P < 0.001). In the surgical group, beneficial changes of almost all quantitative variables correlated significantly with the decrease in BMI. We conclude that Roux‐en‐Y gastric bypass surgery when compared to severely obese groups not enrolled in planned weight‐loss intervention was highly effective for weight loss, improved health‐related quality of life, and resolution of major obesity‐associated complications measured at 2 years.

Effects of Exercise Training on Chronic Inflammation in Obesity

Chronic, systemic inflammation is an independent risk factor for several major clinical diseases. In obesity, circulating levels of inflammatory markers are elevated, possibly due to increased production of pro-inflammatory cytokines from several tissues/cells, including macrophages within adipose tissue, vascular endothelial cells and peripheral blood mononuclear cells. Recent evidence supports that adipose tissue hypoxia may be an important mechanism through which enlarged adipose tissue elicits local tissue inflammation and further contributes to systemic inflammation. Current evidence supports that exercise training, such as aerobic and resistance exercise, reduces chronic inflammation, especially in obese individuals with high levels of inflammatory biomarkers undergoing a longer-term intervention. Several studies have reported that this effect is independent of the exercise-induced weight loss. There are several mechanisms through which exercise training reduces chronic inflammation, including its effect on muscle tissue to generate muscle-derived, anti-inflammatory ‘myokine’, its effect on adipose tissue to improve hypoxia and reduce local adipose tissue inflammation, its effect on endothelial cells to reduce leukocyte adhesion and cytokine production systemically, and its effect on the immune system to lower the number of pro-inflammatory cells and reduce pro-inflammatory cytokine production per cell. Of these potential mechanisms, the effect of exercise training on adipose tissue oxygenation is worth further investigation, as it is very likely that exercise training stimulates adipose tissue angiogenesis and increases blood flow, thereby reducing hypoxia and the associated chronic inflammation in adipose tissue of obese individuals.

Metabolic syndrome and risk of cancer mortality in men

BACKGROUND Metabolic syndrome (MetS) has been linked with an increased risk of developing cancer; however, the association between MetS and cancer mortality remains less clear. Little research has focused on pre-cancer risk factors that may affect the outcome of treatment. The purpose of this study was to examine the association between MetS and all-cancer mortality in men. METHODS The participants included 33,230 men aged 20-88 years who were enrolled in the Aerobics Centre Longitudinal Study and who were free of known cancer at the baseline. RESULTS At baseline 28% of all the participants had MetS. During an average of 14 years follow-up, there were a total of 685 deaths due to cancer. MetS at baseline was associated with a 56% greater age-adjusted risk in cancer mortality. CONCLUSION These data show that MetS is associated with an increased risk of all-cause cancer mortality in men. Based on these findings, it is evident that successful interventions should be identified to attenuate the negative effects of MetS.