Effects of physical activity on exercise tests and respiratory function

Obesity is associated with altered lung function independently of physical activity and fitness

Measures of obesity, especially central adiposity, have been associated with reduced lung function. However, previous studies may have been affected by confounding by physical activity and fitness. This study aimed to examine the relationship among body fatness, fat distribution, and lung function, adjusted for physical activity energy expenditure (PAEE) and aerobic fitness (VO(2)max), in a cohort of British white adults with a family history of type 2 diabetes. A total of 320 adults (mean age 40.4 +/- 6.0 years) attended for anthropometric and VO(2)max testing, and had ambulatory heart rate monitoring for 4 days to determine PAEE. Spirometry was used to measure forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC). The tests were repeated 12 months later, and a cross-sectional analysis using linear regression with repeated measures was performed. Measures of obesity (BMI, waist circumference (WC), fat mass (FM), body fat percentage (BF%)) were associated with lower lung function in men and women (P < 0.01), while waist-to-hip ratio (WHR) was associated with lower lung function in men only (P < 0.001). Associations remained after adjusting for age, smoking status, height, PAEE, and VO(2)max. The estimated difference in mean FEV(1) and FVC per unit increase in the exposure measures were consistently stronger in men compared to women (P for interaction <0.001). Obesity is inversely associated with lung function in adults, but central fat distribution appears to have a stronger relationship with respiratory mechanics in men than in women. These associations were independent of the degree of physical activity and aerobic fitness in this cohort.

Prospective study of physical activity and lung cancer by histologic type in current, former, and never smokers

Increased physical activity has been associated with decreased lung cancer risk. However, no previous investigation has examined physical activity in relation to lung cancer histologic types by smoking status. The authors investigated these relations in the National Institutes of Health-AARP Diet and Health Study among 501,148 men and women aged 50-71 years at baseline in 1995-1996. During follow-up to 2003, 6,745 lung carcinomas occurred (14.8% small cell, 40.3% adenocarcinoma, 19.7% squamous cell, 6.1% undifferentiated large cell, 7.2% non-small cell not otherwise specified, and 11.8% carcinoma not otherwise specified). Among former smokers, the multivariate relative risks of small cell, adenocarcinoma, squamous cell, and undifferentiated large cell carcinomas comparing the highest with the lowest activity level (> or =5 times/week vs. inactive) were 0.93 (95% confidence interval (CI): 0.67, 1.28), 0.79 (95% CI: 0.67, 0.94), 0.73 (95% CI: 0.57, 0.93), and 0.61 (95% CI: 0.38, 0.98), respectively. Among current smokers, corresponding values were 0.77 (95% CI: 0.58, 1.02), 0.76 (95% CI: 0.61, 0.95), 0.85 (95% CI: 0.65, 1.11), and 1.10 (95% CI: 0.69, 1.78). In contrast, physical activity was unrelated to lung carcinoma among never smokers (P(interaction) between physical activity and smoking for total lung carcinomas = 0.002). The inverse findings among former and current smokers in combination with the null results for physical activity among never smokers may point toward residual confounding by cigarette smoking as an explanation for the relations observed.

Time-dependent confounding in the study of the effects of regular physical activity in chronic obstructive pulmonary disease: an application of the marginal structural model

PURPOSE

Results from longitudinal studies about the association between physical activity and chronic obstructive pulmonary disease (COPD) may have been biased because they did not properly adjust for time-dependent confounders. Marginal structural models (MSMs) have been proposed to address this type of confounding. We sought to assess the presence of time-dependent confounding in the association between physical activity and COPD development and course by comparing risk estimates between standard statistical methods and MSMs.

METHODS

By using the population-based cohort Copenhagen City Heart Study, 6,568 subjects selected from the general population in 1976 were followed up until 2004 with three repeated examinations.

RESULTS

Moderate to high compared with low physical activity was associated with a reduced risk of developing COPD both in the standard analysis (odds ratio [OR] 0.76, p = 0.007) and in the MSM analysis (OR 0.79, p = 0.025). In the subgroup with COPD (n = 2,226), high physical activity was associated with a reduced risk of COPD admissions during follow-up (standard, incidence rate ratio, 0.74; p = 0.096; MSM, 0.68, p = 0.044), and with a reduced risk of mortality (standard, hazard ratio 0.80, p = 0.001; MSM, 0.81, p = 0.008).

CONCLUSION

These results support the previously reported associations between physical activity and reduced risk of COPD development, hospitalizations, and mortality, thereby suggesting they were not due to time-dependent confounding.

Effects of chronic smoking on exercise tolerance and on heart rate-systolic blood pressure product in young healthy adults

BACKGROUND

Smoking is a major cause of cardiovascular disease and mortality. Smoking-related deaths in Greece account for 23%, whereas 41% of young Greeks are smokers, the highest percentage in Europe. The purpose of this study was to examine the effects of chronic smoking on the rate-pressure product and exercise tolerance in young, healthy male smokers.

DESIGN AND METHODS

Forty-two smokers and 51 nonsmokers were selected from a population of 543 students based on their age, sex, body mass index, physical fitness, smoking habit and health status. All participants were tested with the standard Bruce treadmill protocol. The rate-pressure product was obtained at rest and during exercise at a given submaximal workload. The evaluation of exercise tolerance was based on peak workload achieved and maximal exercise test duration.

RESULTS

The smokers had a higher rate-pressure product at rest (P<0.001) due to their higher resting heart rate (P<0.001). Resting values of blood pressure did not differ significantly between the two groups. During exercise, smokers had a greater rate-pressure product (P<0.001), mainly due to their significantly higher systolic blood pressure (P=0.008). The smokers had a higher submaximal heart rate (P=0.005), but the differences in heart rate between groups were reduced for smokers during exercise when compared to rest. The smokers' exercise tolerance was impaired and their maximal exercise test duration time was significantly shorter (P<0.001).

CONCLUSIONS

Chronic smoking was found to affect young male smokers' cardiovascular fitness, impairing the economy and decreasing the capacity of their circulatory system.

[Lipid and metabolic profiles in adolescents are affected more by physical fitness than physical activity (AVENA study)]

INTRODUCTION AND OBJECTIVES

To determine whether the level of physical activity or physical fitness (i.e., aerobic capacity and muscle strength) in Spanish adolescents influences lipid and metabolic profiles.

METHODS

From a total of 2859 Spanish adolescents (age 13.0-18.5 years) taking part in the AVENA (Alimentación y Valoración del Estado Nutricional en Adolescentes) study, 460 (248 male, 212 female) were randomly selected for blood analysis. Their level of physical activity was determined by questionnaire. Aerobic capacity was assessed using the Course-Navette test. Muscle strength was evaluated using manual dynamometry, the long jump test, and the flexed arm hang test. A lipid-metabolic cardiovascular risk index was derived from the levels of triglycerides, low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDLC), and glucose.

RESULTS

No relationship was found between the level of physical activity and lipid-metabolic index in either sex. In contrast, there was an inverse relationship between the lipid-metabolic index and aerobic capacity in males (P=.003) after adjustment for physical activity level and muscle strength. In females, a favorable lipid-metabolic index was associated with greater muscle strength (P=.048) after adjustment for aerobic capacity.

CONCLUSIONS

These results indicate that, in adolescents, physical fitness, and not physical activity, is related to lipid and metabolic cardiovascular risk. Higher aerobic capacity in males and greater muscle strength in females were associated with lower lipid and metabolic risk factors for cardiovascular disease.

Regular physical activity modifies smoking-related lung function decline and reduces risk of chronic obstructive pulmonary disease: a population-based cohort study

RATIONALE

We have previously reported that regular physical activity reduces risk of chronic obstructive pulmonary disease (COPD) exacerbation. We hypothesized that higher levels of regular physical activity could reduce the risk of COPD by modifying smoking-related lung function decline.

OBJECTIVE

To estimate the longitudinal association between regular physical activity and FEV(1) and FVC decline and COPD risk.

METHODS

A population-based sample (n = 6,790) was recruited and assessed with respect to physical activity, smoking, lung function, and other covariates, in Copenhagen in 1981-1983, and followed until 1991-1994. Mean level of physical activity between baseline and follow-up was classified into "low," "moderate," and "high." FEV(1) and FVC decline rates were expressed as milliliters per year. COPD was defined as FEV(1)/FVC < or = 70%. Adjusted associations between physical activity and FEV(1) and FVC decline, and COPD incidence, were obtained using linear and logistic regression, respectively.

RESULTS

Active smokers with moderate and high physical activity had a reduced FEV(1) and FVC decline compared with those with low physical activity (relative change of +2.6 and +4.8 ml/yr of FEV(1), P-for-trend = 0.006, and +2.6 and +7.7 ml/yr of FVC, P-for-trend < 0.0001, for the moderate and high physical activity group, respectively), after adjusting for all potential confounders and risk factors of lung function decline. Active smokers with moderate to high physical activity had a reduced risk of developing COPD as compared with the low physical activity group (odds ratio, 0.77; p = 0.027).

CONCLUSIONS

This prospective study shows that moderate to high levels of regular physical activity are associated with reduced lung function decline and COPD risk among smokers.

Longitudinal changes in physical functional performance among the oldest old: insight from a study of Swedish twins

AIMS AND METHODS

The primary purpose was to characterize mean and individual-level patterns of change in physical functional performance over eight years (2 year intervals) in a community dwelling sample of Swedish twins (579 men and women aged 79-96 years at baseline).

RESULTS

Mixed linear models revealed linear rates of decline for handgrip strength (grip) and time to complete five chair stands, and accelerating decline for peak expiratory flow rate (PEFR) for both sexes. Significant random effects were found for intercept and time for grip and PEFR tests, indicating differences between participants initially and over time. Individual differences in chair-stand performance were significant for initial status only. Age at baseline was predictive of initial status in grip, PEFR and chair performance (women only), but not rate of change. Measures of body size at baseline were predictive of individual variation in initial grip (height), PEFR (weight in men, height in women), and chair performance (height), but had less consistent associations with changes in test performance over time. In the deceased sub-sample (85% of participants), having been further from death was related to less steep declines in grip, but not PEFR or chair performance. Twins from the same pair were related in initial status (twin level variance ~30-70%), but they were not generally related in rate of change.

CONCLUSIONS

These results indicate that changes in physical functional performance in an elderly, community-dwelling population vary across individuals in a testand sex-dependent manner. Constitutional variables (age, sex, body size) are predictive of baseline performance, but explain little variance in change over time. Initial status and rate of change in grip strength had the strongest association with proximity from death, indicating that while PEFR and repeated chair stand time are useful tests to assess function, grip strength appears to be a particularly useful biomarker in the oldest-old.

Long-term physical activity in leisure time and mortality from coronary heart disease, stroke, respiratory diseases, and cancer. The Copenhagen City Heart Study

BACKGROUND

The purpose of this study was to describe the associations between different levels of long-term physical activity in leisure time and subsequent causes of deaths.

DESIGN

The Copenhagen City Heart Study is a prospective cardiovascular population study of 19 329 men and women aged 20-93 in 1976. Physical activity in leisure time was estimated at the examinations in 1976-78 and 1981-83. This analysis consists of 2136 healthy men and 2758 women aged 20-79 years, with unchanged physical activity at the two examinations, and with all covariates included in the multivariate analyses: smoking, total-cholesterol, high-density lipoprotein-cholesterol, systolic blood pressure, diabetes mellitus, alcohol consumption, body mass index, education, income, and forced expiratory volume in 10.78 (% predicted).

RESULTS

Adjusted relative risks (95% confidence interval) for coronary heart disease were, for moderate physical activity 0.71 (0.51, 0.99) and for high 0.56 (0.38, 0.82). For cancer, moderate activity 0.77 (0.61, 0.97) and high activity 0.73 (0.56, 0.95) and for all-cause mortality, moderate 0.78 (0.68, 0.89) and high 0.75 (0.64, 0.87) for both sexes combined. Using Kaplan-Meier plots we calculated gained years of expected lifetime from age 50. Men with high physical activity survived 6.8 years longer, and men with moderate physical activity 4.9 years longer than sedentary men. For women the figures were 6.4 and 5.5 years, respectively.

CONCLUSION

Long-term moderate or high physical activity was in both sexes associated with significantly lower mortality from coronary heart disease, cancer and all-causes. The same tendency was found for stroke and respiratory diseases, but the associations did not reach statistical significance.

Tobacco harm reduction strategies: The case for physical activity

Since the effects of tobacco smoke are so detrimental to health, growing consideration has been given to the development of harm reduction strategies for those smokers who are unable or unwilling to stop using tobacco. The term harm reduction refers to a policy, strategy, or particular intervention that assumes continued use of an undesired behavior and aspires to lower the risk of adverse consequences associated with the continuation of this addictive behavior. Up to this point, tobacco harm reduction interventions have focused on reducing tobacco-related harm through the utilization of innovative tobacco products, reduced tobacco consumption, and pharmaceutical medications. With the possible exception of medicinal nicotine products, these strategies remain unproven and thus far no scientific or medical literature exists to suggest these harm reduction strategies reduce tobacco-related exposure, morbidity, or mortality. Consequently, a need exists for broadening the range of potentially effective harm reduction strategies. This preliminary review suggests that physical activity has the potential to become one such strategy. Of the eight principles that characterize a harm reduction strategy, all are at least partially satisfied by physical activity. Further, emerging evidence indicates that physical activity may delay the occurrence of disease and premature death initiated by tobacco consumption. Significant concerns remain regarding the practicality of physical activity as a harm reduction strategy and the extent to which participation in physical activity may be used to justify continued smoking.

Inverse association between physical inactivity and mental health in men and women

PURPOSE

The Aerobics Center Longitudinal Study (ACLS) provides the opportunity to evaluate associations between measures of physical activity and mental health in a large and well-characterized population of men and women.

METHODS

Participants were 5451 men and 1277 women (20-88 yr) who completed a maximal fitness treadmill test and self-report measures of habitual physical activity, depressive symptoms (Center for Epidemiological Studies Scale for Depression; CES-D) and emotional well-being (General Well-Being Schedule; GWB). To evaluate the dose-response gradient of the association, we classified the sample, separately for men and women, into three levels of relative cardiorespiratory (CR) fitness (low, moderate, high) on the maximal treadmill test, and four levels on a physical activity index of weekly walking, jogging, and running.

RESULTS

In both men and women, there was a significant inverse graded dose-response relationship between maximal CR fitness and the CES-D score (P < 0.0001), and a significant positive graded dose-response relationship between CR fitness and the GWB score (P < 0.0001). We also observed dose-response associations between the level of physical activity and both CES-D and GWB scores (P < 0.0001) that peaked at 11-19 miles per week.

CONCLUSION

Among men and women in the ACLS, relative increases in maximal CR fitness and habitual physical activity are cross-sectionally associated with lower depressive symptomatology and greater emotional well-being. Prospective epidemiological studies and controlled clinical trials are needed to identify the minimal and optimal levels of physical activity and CR fitness associated with various mental health benefits in different segments of the general population.

Mejora de la forma física como terapia antienvejecimiento

Several recent important studies have clearly shown that a low physical fitness represents a potent risk factor and even a predictor of both cardiovascular and all-causes morbidity and mortality. As a consequence, physical fitness assessment should be performed at the clinical level since, when properly assessed, it is a highly valuable health and life expectancy indicator. Based on the results of fitness assessment in a particular person and knowing his/her life style and daily physical activity, an individually adapted training program can be prescribed. This training program will allow that person to develop his/her maximal physical potential while improving his/her physical and mental health and attenuating the deleterious consequences of aging. In fact, physical exercise is today proposed as a highly effective means to treat and prevent major morbidity and mortality causes in industrialized countries. Most of these causes are associated with the aging process. In order to be effective, this type of intervention should be directed to improve the aerobic capacity and strength. In addition, it should be complemented with work directed to improve the general coordination and flexibility. Finally, diet optimization and use of nutritional supplements and legal ergogenic aids are key elements to improve the functional capacity and health, all of which is synonymous of anti-aging interventions.