Sara K. Rosenkranz

Does Moderate Intensity Exercise Attenuate the Postprandial Lipemic and Airway Inflammatory Response to a High-Fat Meal?

We investigated whether an acute bout of moderate intensity exercise in the postprandial period attenuates the triglyceride and airway inflammatory response to a high-fat meal (HFM) compared to remaining inactive in the postprandial period. Seventeen (11 M/6 F) physically active (≥150 min/week of moderate-vigorous physical activity (MVPA)) subjects were randomly assigned to an exercise (EX; 60% VO2peak) or sedentary (CON) condition after a HFM (10 kcal/kg, 63% fat). Blood analytes and airway inflammation via exhaled nitric oxide (eNO) were measured at baseline, and 2 and 4 hours after HFM. Airway inflammation was assessed with induced sputum and cell differentials at baseline and 4 hours after HFM. Triglycerides doubled in the postprandial period (~113 ± 18%, P < 0.05), but the increase did not differ between EX and CON. Percentage of neutrophils was increased 4 hours after HFM (~17%), but the increase did not differ between EX and CON. Exhaled nitric oxide changed nonlinearly from baseline to 2 and 4 hours after HFM (P < 0.05,  η 2 = 0.36). Our findings suggest that, in active individuals, an acute bout of moderate intensity exercise does not attenuate the triglyceride or airway inflammatory response to a high-fat meal.

Sex differences in pulmonary function during exercise.

Structural and hormonal sex differences are known to exist that may influence the pulmonary systems response to exercise. Specifically, women tend to show reduced lung size, decreased maximal expiratory flow rates, reduced airway diameter, and a smaller diffusion surface than age- and height-matched men. Additionally, ovarian hormones, namely progesterone and estrogen, are known to modify and influence the pulmonary system. These differences may have an effect on airway responsiveness, ventilation, respiratory muscle work, and pulmonary gas exchange during exercise. Recent evidence suggests that during exercise, women demonstrate greater airway hyperresponsiveness and expiratory flow limitation, increased work of breathing, and, perhaps, greater exercise-induced arterial hypoxemia compared with men. The consequence of these pulmonary effects may influence exercise capacity.

Dysanapsis ratio as a predictor for expiratory flow limitation.

To determine the efficacy of the dysanapsis ratio (DR) in predicting expiratory flow limitation during exercise, 146 subjects (73 men, 73 women) performed standard pulmonary function and maximal incremental exercise tests. Tidal flow-volume loops were recorded at maximal exercise with maximal flow-volume loops measured pre- and post-exercise. Men had larger (p<0.05) lung volumes, flow rates, and V˙O2max compared to women, but DR was similar (0.21±0.05 vs. 0.20±0.06, respectively, p>0.05). V˙O2max was not different (p>0.05) between the EFL subjects compared to the non-EFL subjects for both men and women. Men with EFL compared to non-EFL men had smaller FVC (5.16±0.89L vs. 5.67±0.86L, p<0.05) and DR (0.19±0.05 vs. 0.23±0.04, p<0.05). Similarly, women with EFL compared to non-EFL had significantly smaller DR (0.18±0.05 vs. 0.24±0.05), but similar FVC (3.88±0.52 vs. 4.12±0.64, p>0.05). A DR threshold was not determined; however, a DR continuum exists with increasing DR leading to decreased prevalence of EFL. In conclusion, DR is effective in determining the likelihood of EFL at maximal exercise.

Expiratory flow limitation during exercise in prepubescent boys and girls: prevalence and implications

The purpose of this study was to compare the prevalence and implications of expiratory flow limitation (EFL) during exercise in boys and girls. Forty healthy, prepubescent boys (B; n=20) and girls (G; n=20) were tested. Subjects completed pulmonary function tests and an incremental cycle maximal oxygen uptake (VO2max) test. EFL was recorded at the end of each exercise stage using the % tidal volume overlap method. Ventilatory and metabolic data were recorded throughout exercise. Arterial oxygen saturation (SpO2) was determined via pulse oximetry. Body composition was determined using dual-energy X-ray absorptiometry. There were no differences (P>0.05) in height, weight, or body composition between boys and girls. At rest, boys had significantly higher lung volumes (total lung capacity, B=2.6+/-0.5 liters, G=2.1+/-0.5 liters) and peak expiratory flow rates (B=3.6+/-0.6 l/s; G=1.6+/-0.3 l/s). Boys also had significantly higher VO2max (B=46.9+/-5.9 ml.kg lean body mass(-1).min(-1), G=41.7+/-6.6 ml.kg lean body mass(-1).min(-1)) and maximal ventilation (B=49.8+/-8.8 l/min, G=41.2+/-8.3 l/min) compared with girls. There were no sex differences (P>0.05) at VO2max in VE /VCO2, end-tidal PCO2, heart rate, respiratory exchange ratio, or SpO2. The prevalence (B=19/20 vs. G=18/20) and severity (B=58+/-7% vs. G=43+/-8% tidal volume) of EFL was not significantly different in boys compared with girls at VO2max. A significant relationship existed between % EFL at VO2max and the change in end-expiratory lung volume from rest to maximal exercise in boys (r=0.77) and girls (r=0.75). In summary, our data suggests that EFL is highly and equally prevalent in prepubescent boys and girls during heavy exercise, which led to an increased end-expiratory lung volume but not to decreases in arterial oxygen saturation.

Dietary factors associated with lifetime asthma or hayfever diagnosis in Australian middle-aged and older adults: a cross-sectional study

BackgroundThere is abundant research relevant to genetic and environmental influences on asthma and hayfever, but little is known about dietary risk factors in Australian adults. This study’s purpose was to identify dietary factors associated with lifetime asthma (AS) and asthma or hayfever (AS/HF) diagnosis in Australian middle-aged and older adults.MethodsFrom The 45 and Up Study baseline self-report data, this study included 156,035 adult men and women. Participants were sampled from the general population of New South Wales, Australia in 2006–2009. About 12% of participants reported ever receiving an AS diagnosis (men 10%; women 14%) and 23% reported AS/HF diagnosis (men 19%; women 26%). Following principle components factor analysis, dietary items loaded onto one of four factors for men (meats/cheese; fruits/vegetables; poultry/seafood; grains/alcohol) or five factors for women (meats; fruits/vegetables; poultry/seafood; cereal/alcohol; brown bread/cheese). Logistic regression was used to analyze the associations between dietary factors and AS or AS/HF diagnosis.ResultsFor men, the meats/cheese factor was positively associated with AS (AOR = adjusted odds ratio for highest versus lowest quintile = 1.18, 95%CI = 1.08, 1.28; Ptrend = 0.001) and AS/HF (AOR for highest versus lowest quintile = 1.22, 95%CI = 1.14, 1.29; Ptrend < 0.001). Poultry/seafood was also associated with AS/HF in men (AOR for highest versus lowest quintile = 1.11, 95%CI = 1.04, 1.17; Ptrend = 0.002). For women, significant risk factors for AS/HF included meats (AOR for highest versus lowest quintile = 1.25, 95%CI = 1.19, 1.31; Ptrend = 0.001), poultry/seafood (AOR for highest versus lowest quintile = 1.06, 95%CI = 1.01, 1.12; Ptrend = 0.016), and fruits/vegetables (AOR for highest versus lowest quintile = 1.07, 95%CI = 1.02, 1.12; Ptrend = 0.011). In contrast, the cheese/brown bread dietary factor was protective against AS in women (AOR for highest versus lowest quintile = 0.88, 95%CI = 0.82, 0.94; Ptrend < 0.001).ConclusionsGenerally, diets marked by greater intakes of meats, poultry, and seafood were associated with diagnosed AS and AS/HF. Taken together, these findings suggest that adherence to a more meat-based diet may pose risk for AS and AS/HF in Australian adults.

High-intensity training improves airway responsiveness in inactive nonasthmatic children: evidence from a randomized controlled trial

PURPOSE the relationship between physical activity and airway health in children is not well understood. The purpose of this study was to determine whether 8 wk of high-intensity exercise training would improve airway responsiveness in prepubescent, nonasthmatic, inactive children. METHODS 16 healthy, prepubescent children were randomized [training group (TrG) n = 8, control group (ConG) n = 8]. Prior to and following 8 wk of training (or no training), children completed pulmonary function tests (PFTs): forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75)), and exhaled nitric oxide (FENO). Children completed an incremental cycle Vo(2max) test, eucapnic voluntary hyperventilation (EVH), anthropometric tests, and blood tests to determine fasting blood glucose, total cholesterol, HDL, LDL, and triglycerides. Body fat percentage was determined using dual-energy X-ray absorptiometry pretraining and bioelectrical impedance pre- and posttraining. RESULTS there were no differences (P > 0.05) in anthropometric measures or PFTs between TrG and ConG at baseline. In the TrG, there was a significant increase in Vo(2max) (∼24%) and a decrease in total cholesterol (∼13%) and LDL cholesterol (∼35%) following training. There were improvements (P < 0.05) in ΔFEV(1) both postexercise (pre: -7.60 ± 2.10%, post: -1.10 ± 1.80%) and post-EVH (pre: -6.71 ± 2.21%, post: -1.41 ± 1.58%) with training. The ΔFEF(25-75) pre-post exercise also improved with training (pre: -16.10 ± 2.10%, post: -6.80 ± 1.80%; P < 0.05). Lower baseline body fat percentages were associated with greater improvements in pre-post exercise ΔFEV(1) following training (r = -0.80, P < 0.05). CONCLUSION these results suggest that in nonasthmatic prepubescent children, inactivity negatively impacts airway responsiveness, which can be improved with high-intensity training. Excess adiposity, however, may constrain these improvements.

Postprandial lipemic and inflammatory responses to high-fat meals: a review of the roles of acute and chronic exercise

Postprandial lipemia is an independent risk factor for development of cardiovascular disease. Postprandial inflammation following the prolonged elevation of triglycerides occurring subsequent to ingestion of high-fat meals, provides a likely explanation for increased disease risk. Substantial evidence has shown that acute exercise is an effective modality for attenuation of postprandial lipemia following a high-fat meal. However, much of the evidence pertaining to exercise intensity, duration, and overall energy expenditure for reducing postprandial lipemia is inconsistent. The effects of these different exercise variables on postprandial inflammation is largely unknown. Long-term, frequent exercise, however, appears to effectively reduce systemic inflammation, especially in at-risk or diseased individuals. With regard to an acute postprandial response, without a recent bout of exercise, high levels of chronic exercise do not appear to reduce postprandial lipemia. This review summarizes the current literature on postprandial and inflammatory responses to high-fat meals, and the roles that both acute and chronic exercise play. This review may be valuable for health professionals who wish to provide evidence-based, pragmatic advice for reducing postprandial lipemia and cardiovascular disease risk for their patients. A brief review of proposed mechanisms explaining how high-fat meals may result in pro-inflammatory and pro-atherosclerotic environments is also included.

Magnitude and Timing of the Postprandial Inflammatory Response to a High-Fat Meal in Healthy Adults: A Systematic Review

Research findings over the past several decades have shown that inflammation is a prominent feature of many chronic diseases, with poor diet being one likely inflammatory stimulus. Specifically, a single high-fat meal (HFM) has been suggested to increase inflammation, although there is currently no consensus with regard to the specific changes in many of the proinflammatory markers that are frequently assessed after an HFM. The aim of this systematic review was to objectively describe the postprandial timing and magnitude of changes in 5 common inflammatory markers: interleukin (IL) 6, C-reactive protein (CRP), tumor necrosis factor (TNF) α, IL-1β, and IL-8. Ten relevant databases were searched, yielding 494 results, of which 47 articles met the pre-established inclusion criteria: 1) healthy men and women aged 18-60 y, 2) consuming a single HFM (≥30% fat, ≥500 kcal), and 3) assessing relevant inflammatory markers postmeal for ≥2 h. The only marker found to consistently change in the postprandial period was IL-6: on average, from a baseline of ∼1.4 pg/mL, it peaked at ∼2.9 pg/mL ∼6 h post-HFM (an average relative change of ∼100%). CRP, TNF-α, IL-1β, and IL-8 did not change significantly in 79% (23 of 29), 68% (19 of 28), 67% (2 of 3), and 75% (3 of 4) of included studies, respectively. We conclude that there is strong evidence that CRP and TNF-α are not responsive at the usual time scale observed in postprandial studies in healthy humans younger than age 60 y. However, future research should further investigate the role of IL-6 in the postprandial period, because it routinely increases even in healthy participants. We assert that the findings of this systematic review on markers of inflammation in the postprandial period will considerably aid in informing future research and advancing clinical knowledge.

Comparing the effects of two different break strategies on occupational sedentary behavior in a real world setting: A randomized trial.

Developing interventions to reduce sedentary behavior in the workplace is an important public health priority. Furthermore, research is needed to determine whether different approaches to breaking up prolonged sitting during the workday are equally feasible and effective. Thus, the purpose of this study was to determine whether varying the frequency and duration of activity breaks during the workday would differentially impact sedentary behavior and health outcomes. Inactive females (N = 49) working full-time sedentary jobs were recruited for this parallel-group randomized trial. Participants were randomly assigned to take short, frequent breaks from sitting (1–2 min every half hour; SB) or longer, planned breaks from sitting (two 15-minute breaks per workday; LB) during each workday across an 8-week intervention. Sedentary time and health outcomes were assessed at baseline and post-intervention. The study ran from March 2014–June 2015. Results showed sedentary time during the workday decreased significantly in the SB group (− 35.6 min; d = − 0.75; p = 0.03), but did not change in the LB group (+ 4.5 min; d = 0.12). Participants in the SB group also demonstrated small-to-moderate declines in total cholesterol (d = − 0.33; p = 0.10), triglycerides (d = − 0.38; p = 0.06) and fasting blood glucose (d = − 0.29; p = 0.01) from pre to post-intervention. Health outcomes did not change in the LB group. This study demonstrated that taking short, frequent breaks from sitting during the workday is a feasible and effective approach for reducing sedentary time at work. These results have implications for the development of public health messages addressing sedentary behavior, and inform future interventions to reduce sedentary time in the workplace. Trial registration This study is registered at www.clinicaltrials.gov: NCT02609438.

Decreased Prevalence of Exercise Expiratory Flow Limitation from Pre- to Postpuberty.

PURPOSE We recently reported a high prevalence of expiratory flow limitation (EFL) independent of sex in prepubescent children that exceeds the prevalence reported in adults. It is unknown how transpubertal maturation and growth affect pulmonary function, specifically EFL, during exercise. The purpose of this longitudinal study was to investigate the changes in EFL, including sex differences, from pre- to postpuberty. METHODS Twenty-one children (age 12-16 yr, 11 boys and 10 girls) were recruited from 40 prepubescent children who completed testing in our laboratory ∼5 yr ago. Subjects completed pulmonary function tests before and after an incremental exercise test to exhaustion on a cycle ergometer. EFL was determined using the percent tidal volume overlap method. RESULTS Nineteen of 21 subjects (10 boys and 9 girls, ∼90%) exhibited EFL prepuberty, whereas only 7 of 21 subjects (5 boys and 2 girls, 33%) exhibited EFL postpuberty. Boys had a significantly greater forced vital capacity (FVC) than girls both pre- (∼15%) and postpuberty (boys: 4.73 ± 0.53 L; girls: 3.80 ± 0.29 L). Maximal aerobic capacity (V˙O2max) significantly increased (boys: ∼120%; girls: ∼110%) from pre- to postpuberty and was greater (P < 0.05) in boys postpuberty (boys: 2.76 ± 0.43 L·min; girls: 1.94 ± 0.35 L·min). V˙E/V˙CO2 significantly decreased (∼13%) in boys and girls during maximal exercise. Postpuberty, subjects regulated tidal breathing at significantly higher lung volumes (greater expiratory reserve volume/FVC and lower inspiratory reserve volume/FVC) during exercise compared with prepuberty. CONCLUSION Our findings suggest that the prevalence of EFL declines as children mature from pre- to postpuberty, likely because of increases in lung size, decreases in V˙E/V˙CO2, and/or changes in breathing mechanics that are greater than increases in maximal ventilation that occur with increased pulmonary gas exchange.