Increase in physical activity energy expenditure is associated with reduced metabolic risk independent of change in fatness and fitness

The impact of the covid-19 pandemic on lifestyle behaviors in U.S. college students

OBJECTIVE

To investigate COVID-19's impact on college student health behaviors.

PARTICIPANTS

189 college students.

METHODS

Participants completed an online survey on behaviors relating to sleep, sedentary activities, and physical activity before and during the COVID-19 pandemic. Comparisons utilized Students' dependent t-test or Wilcoxon signed-rank tests.

RESULTS

There was an increase in time to fall asleep (before: 23.4 ± 18.0 vs. during: 42.8 ± 44.3 min·day^-1, p < 0.001), time spent in bed (before: 7.8 ± 1.5 vs. during: 8.5 ± 1.5 hr·day^-1, p < 0.001), as well as shifts in later bed and awake time (p < 0.001). Total sedentary time increased during the pandemic (before: 9.0 ± 3.8 vs. during: 9.9 ± 4.1 hr·day^-1, p = 0.016); and time spent using a TV, computer, or phone (before: 3.1 ± 1.9 vs. during: 4.2 ± 2.3 hr·day^-1, p < 0.001). There was a significant decrease in moderate-vigorous activity (before: 123.8 ± 96.0 vs. during: 108.9 ± 75.5 min·week^-1, p = 0.028) and resistance training days (before: 2.4 ± 2.1 vs. during: 1.7 ± 2.1 days·week^-1, p < 0.001).

CONCLUSIONS

COVID-19 negatively influenced health behaviors in college students.

Fan Cooling Improves Submaximal Exercise Capacity in an Indoor Thermoneutral Environment

Purpose: We compared physiological and perceptual responses to submaximal, moderate-vigorous, heart rate-based cycle ergometry with and without a fan. Methods: Sixteen recreationally active adults (25 ± 3 years; 8 men and 8 women) participated in the study. After an initial visit to assess cardiorespiratory fitness, each participant performed two 40-min training sessions on a cycle ergometer, either with or without a fan (~4 m/s), while workload was continually adjusted to elicit and maintain 70% of heart rate reserve. Workload, oxygen cost, and respiratory exchange ratio were monitored throughout, and rating of perceived exertion (RPE) and thermal sensation were recorded every 5 min. Blood lactate was recorded pre-, mid-, and post-sessions and nude body mass was obtained pre-post. Results: Greater (p < .01) mean workload (+15%) and oxygen consumption (+9%) yielded significantly greater (p < .01) energy expenditure with fan cooling (344 ± 124 kcals) compared to without fan cooling (302 ± 103 kcals). Thermal sensation, but not RPE (p = .09), was lower (p < .01) with fan cooling (3.8 ± 0.7) compared to without fan cooling (5.5 ± 0.8), and body mass loss was attenuated (p < .05) with fan cooling (-0.4 ± 0.2 kg) compared to the non-fan trial (-0.6 ± 0.3 kg). Significantly higher (p < .05) blood lactate values were observed in Fan (3.0 ± 1.9 mmol/l) vs. No Fan (2.5 ± 1.4 mmol/l) trials. Conclusions: Fan cooling during submaximal, moderate-vigorous intensity cycle ergometry significantly enhanced work capacity and energy expenditure without increasing perceived exertion. These data highlight the utility of fan cooling as a means to increase the effectiveness of indoor, heart rate-based cycle training.

Effects of Methylenetetrahydrofolate Reductase (MTHFR) Polymorphisms on Retinal Tissue Perfusion in Mild Diabetic Retinopathy Patients Receiving the Medical Food, Ocufolin®

Purpose

We evaluate the effects of methylenetetrahydrofolate reductase (MTHFR) polymorphisms on retinal tissue perfusion in patients with mild diabetic retinopathy (DR + PM) taking the medical food, Ocufolin^®, for 6 months.

Methods

Prospective, case-controlled study. Eight early diabetic retinopathy patients with common reduced function MTHFR polymorphisms (DR+PM) and 15 normal controls (NC) were recruited. MTHFR polymorphisms were subtyped as normal, C677T, or A1298C. Best corrected visual acuity (BCVA) was evaluated. Retinal blood flow velocity (BFV) was measured using Retinal Function Imager. Retinal tissue perfusion (RTP, blood flow rate per inner retinal volume) was calculated within a 2.5 mm diameter circle centered on the fovea. The medical food is intended to address ocular ischemia with high doses of vitamin B-complexes and antioxidants, including L-methylfolate, methylcobalamin, zinc, copper, lutein, vitamins C, D, E, and n-acetylcysteine. The subjects were provided with a medical food for a period of 6 months.

Results

BCVA and vascular indices of DR + PM patients at baseline were initially below those of NC and improved after medical food. Compared to baseline, DR + PM patients after the medical food had significantly improved BCVA during the follow-up period (P < 0.05). In comparison, overall RTP and arteriolar BFV were significantly increased at 6 months (P < 0.05). The changes varied with MTHFR subtypes. In patients with the C677T and the C677T/A1298C compound mutations, RTP was increased at 6 months as compared to that at baseline and 4 months (P < 0.05). In patients with only the A1298C mutation, all microcirculation metrics were increased from baseline at 4 and 6 months, but with less improvement at 6 months than at 4 months (P < 0.05).

Conclusion

Medical food was effective in improving both visual acuity and retinal tissue perfusion in DR + PM patients. The degree of improvement of retinal microcirculation varied among MTHFR subtypes.

Aerobic or Muscle-Strengthening Physical Activity: Which Is Better for Health?

ABSTRACT

The Physical Activity Guidelines recommend performing 150 min of moderate- to vigorous-intensity aerobic physical activity (MVPA) per week. These guidelines also recommend muscle-strengthening physical activity (MSPA) on ≥2 d·wk-1 for additional benefits including muscular fitness and bone health. The majority of the scientific evidence supporting the PA recommendations for health comes from studies of MVPA while the possible contributions of MSPA in these findings have been overlooked historically. Emerging evidence suggests that MSPA can independently protect against major cardiometabolic risk factors, chronic diseases, and mortality. Additional data from clinical trials indicate that many of the well-known health benefits of exercise, like improvements in cardiovascular disease risk factors, are more robust with combined MVPA and MSPA. This review will clarify the relative benefits of MSPA versus MVPA on health-related outcomes to determine the best type of PA for health.

Diurnal variation of fat oxidation rate and energy expenditure in an acute bout of endurance exercise by young healthy males

Background:

Few studies have reported that circadian rhythm affects fat oxidation (FOx) during exercise. Time-of-day causing greater FOx and energy expenditure (EE) during exercise would be beneficial in the prevention of physical inactivity-related health disorders such as metabolic syndrome. The study aims to compare EE and FOx rate after an endurance exercise session done in the morning and late-afternoon hours by apparently healthy young male participants.

Material and Methods:

The present crossover quasi-experimental study involved 10 moderately active but physically untrained male participants of age 18–25 years with normal body mass index. Participants did a steady-state exercise on a motorized treadmill for 30 minutes at a moderate-intensity (50 ± 2% of their heart rate reserve) on two separate occasions at 9:00–10:00 and 15:00–16:00. A similar meal followed by 2 hours of fasting was done before each trial session. During the last 2 minutes of the exercise session, the respiratory gas analysis estimated volume of oxygen (VO₂) and volume of carbon dioxide (VCO₂) consumed in L/min. Indirect calorimetry equations assessed FOx (mg/min), EE (Kcal/min) and respiratory exchange ratio (RER). Data of one participant were removed to adjust for extreme chronotype. Paired t-test was applied, and P ≤ 0.05 was considered significant.

Results:

Morning versus late-afternoon variations in FOx (269 ± 110 vs 290 ± 110, P = 0.016), RER (0.86 ± 0.05 vs 0.85 ± 0.05, P = 0.040), EE (5.454 ± 0.987 vs 5.494 ± 0.959, P = 0.079) and VO2 (1.104 ± 0.201 vs 1.113 ± 0.196, P = 0.035) were present after adjustment for chronotype.

Conclusion:

In an acute bout of endurance, exercise done by young and healthy male individuals, FOx was significantly higher, while EE tends to be higher in late-afternoon than in the morning.

Metabolic syndrome and the benefit of a physical activity intervention on lower-extremity function: Results from a randomized clinical trial

BACKGROUND

In older adults, increases in physical activity may prevent decline in lower-extremity function, but whether the benefit differs according to metabolic syndrome (MetS) status is uncertain. We aim to investigate whether structured physical activity is associated with less decline in lower-extremity function among older adults with versus without MetS.

METHODS

We used data from the multicenter Lifestyle Interventions and Independence for Elders (LIFE) study to analyze 1535 sedentary functionally-vulnerable women and men, aged 70 to 89 years old, assessed every 6 months (February 2010-December 2013) for an average of 2.7 years. Participants were randomized to a structured, moderate-intensity physical activity intervention (PA; n = 766) or health education program (HE; n = 769). MetS was defined according to the 2009 multi-agency harmonized criteria. Lower-extremity function was assessed by 400-m walking speed and the Short Physical Performance Battery (SPPB) score.

RESULTS

763 (49.7%) participants met criteria for MetS at baseline. Relative to HE, PA was associated with faster 400-m walking speed among participants with MetS (P < 0.001) but not among those without MetS (P = 0.91), although the test for statistical interaction was marginally non-significant (P = 0.07). In contrast, no benefit of PA versus HE was observed on the SPPB score in either MetS subgroup.

CONCLUSIONS

Among older adults at high risk for mobility disability, moderate-intensity physical activity conveys significant benefits in 400-m walking speed but not SPPB in those with, but not without, MetS. The LIFE physical activity program may be an effective strategy for maintaining or improving walking speed among vulnerable older adults with MetS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01072500.

The added value of frequent physical activity group sessions in a combined lifestyle intervention: A cluster randomised trial in primary care

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A combined lifestyle intervention improves lifestyle in overweight and obese subjects.

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Real-world setting study shows that changed lifestyle after a combined lifestyle intervention can be sustained.

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Adding group sessions with a physiotherapist had no added value.

Combined lifestyle interventions (CLIs) that target both physical activity (PA) and diet have been shown to improve PA and health of adults who are overweight; however, optimal amount of guidance remains unclear. This study evaluated the effects of adding PA group sessions to a standard CLI in primary care in the Netherlands. 411 participants (BMI 34.5 ± 4.4 kg/m²) in thirty locations were randomised into a one year CLI or CLI+. CLI comprised individual meetings with lifestyle coach (LSC) and physiotherapist, and group meetings with dietician. PA group sessions were added in CLI+. Primary outcome was minutes of moderate to vigorous PA per week. Secondary outcomes of PA, diet and cardiovascular risk factors (i.e. waist circumference, HbA1c and blood pressure) were evaluated after 12 and 24 months with multilevel analyses. Data were collected from 2010 to 2015. Significant between-group effects were only found for waist circumference, which was significantly lower at twelve months in the CLI+ group (p = 0.011), no other between-group differences were found. Several within-group changes were significant. After participating in the intervention, walking time increased with 83 ± 35 min/week and 100 ± 38 min/week, and BMI decreased with 0.7 ± 0.3 kg/m² and 1.5 ± 0.3 kg/m² in CLI and CLI+ respectively (p < 0.001). Diet, HbA1c and systolic blood pressure changed favourably in both groups. Adding PA group sessions did not elicit added, sustained benefits. A programme with individual meetings with LSC and physiotherapist, and group meetings with dietician can be sufficient to facilitate a healthy lifestyle and reduce cardiovascular risk factors in a population with overweight.

Is Active Transport and Leisure-Time Physical Activity Associated With Inflammatory Markers in US Adults? A Cross-Sectional Analyses From NHANES

BACKGROUND

To investigate the association between levels of active transport and leisure-time physical activity (LTPA) with C-reactive protein, white blood cell count, body mass index, waist circumference, and lipids in a large representative sample of adults residing in the United States.

METHODS

Cross-sectional data from the National Health and Nutrition Examination Survey. Adjusted multinomial logistic regressions were carried out to quantify associations between levels of self-reported active transport (or LTPA) and quintiles of anthropometric measures and serum markers.

RESULTS

A total of 3248 adults were included. For serum inflammatory biomarkers, the authors observed a lower likelihood of being in the top quintile groups of circulating C-reactive protein (adjusted odds ratio [aOR]: 0.60; 95% confidence interval [CI], 0.40-0.90) and white blood cell count (aOR: 0.65; 95% CI, 0.44-0.95) with engaging in low to medium levels of active transport but not with high levels of active transport. Higher levels of LTPA were associated with lower likelihood of having high levels of serum inflammatory biomarkers (aOR: 0.60; 95% CI, 0.42-0.86 in the top C-reactive protein group and aOR: 0.58; 95% CI, 0.39-0.87 in top white blood cell group).

CONCLUSIONS

Promoting active transport and/or LTPA may be a beneficial strategy to improving some, but not all, cardiometabolic health outcomes.

Contribution of lower physical activity levels to higher risk of insulin resistance and associated metabolic disturbances in South Asians compared to Europeans

BACKGROUND

Insulin resistance and related metabolic disturbances are major risk factors for the higher T2D risk and associated morbidity and mortality amongst South Asians. The contribution of physical activity to the increased prevalence of insulin resistance and related disturbances amongst South Asians is unknown.

METHODS

We recruited 902 South Asian and European men and women, aged 35-85 years from the ongoing LOLIPOP study. Clinical characterisation comprised standardised questionnaire and measurement of height, weight, waist and hip circumference and blood pressure. Fasting bloods were taken for assessment of glucose, insulin, lipids and HbA1c. Physical activity was quantified using a validated accelerometer, Actigraph GT3X+, worn for 7 days. Univariate and multivariate approaches were used to investigate the relationship between ethnicity, physical activity, insulin resistance and related metabolic disturbances.

RESULTS

Total physical activity was ~31% (P = 0.01) lower amongst South Asians compared to Europeans (Mean MET.minutes [SD]: 1505.2 [52] vs. 2050.9 [86.6], P<0.001). After adjusting for age and sex, total physical activity had a negative association with HOMA-IR (B [SE]: -0.18 [0.08], P = 0.04) and fasting glucose levels (B[SE]: -0.11 [0.04], P = 0.02). There was no association between physical activity and other glycemic and lipid parameters. Total physical activity per week contributed towards the differences in insulin resistance and associated metabolic disturbances between South Asians and Europeans.

CONCLUSION

Lower levels of physical activity may contribute to the increased insulin resistance in South Asians compared to Europeans. Our results suggest that lifestyle modification through increased physical activity may help to improve glucose metabolism and reduce the burden of excess T2D and related complications amongst South Asians.

Promoting physical activity through exergaming in young adults with intellectual disabilities: a pilot study

Various health problems of people with intellectual disabilities (ID) are associated with their physical inactivity. The present study aimed at the understanding of physiological and psychological responses toward exergaming in seven young adults with mild to moderate ID after a single-session and a multiple-session condition, respectively. Their heart rate (HR), the rating of perceived exertion (RPE), and physical activity enjoyment scale (PACES) were measured on control and exergaming sessions. The significant increased HR, which may represent the increased physical activity levels that led to energy expenditure, was observed after a single-session and a multiple-session condition. In addition, the significant increase in RPE and PACES were evident after a single-session condition but a multiple-session condition. The feeling of physical fatigue seems to be distracted by external motivators (e.g. music). However, the positive affectivity to exercise was not noted when exercise was scheduled as their daily routines. This phenomenon might explain the high prevalence of physical inactivity among this population.

Identifying Free-Living Physical Activities Using Lab-Based Models with Wearable Accelerometers

The purpose of this study was to classify, and model various physical activities performed by a diverse group of participants in a supervised lab-based protocol and utilize the model to identify physical activity in a free-living setting. Wrist-worn accelerometer data were collected from (N=152) adult participants; age 18–64 years, and processed the data to identify and model unique physical activities performed by the participants in controlled settings. The Gaussian mixture model (GMM) and the hidden Markov model (HMM) algorithms were used to model the physical activities with time and frequency-based accelerometer features. An overall model accuracy of 92.7% and 94.7% were achieved to classify 24 physical activities using GMM and HMM, respectively. The most accurate model was then used to identify physical activities performed by 20 participants, each recorded for two free-living sessions of approximately six hours each. The free-living activity intensities were estimated with 80% accuracy and showed the dominance of stationary and light intensity activities in 36 out of 40 recorded sessions. This work proposes a novel activity recognition process to identify unsupervised free-living activities using lab-based classification models. In summary, this study contributes to the use of wearable sensors to identify physical activities and estimate energy expenditure in free-living settings.

Spousal cardiometabolic risk factors and incidence of type 2 diabetes: a prospective analysis from the English Longitudinal Study of Ageing

AIMS/HYPOTHESIS

In the UK, more than one million people have undiagnosed diabetes and an additional five million are at high risk of developing the disease. Given that early identification of these people is key for both primary and secondary prevention, new screening approaches are needed. Since spouses resemble each other in cardiometabolic risk factors related to type 2 diabetes, we aimed to investigate whether diabetes and cardiometabolic risk factors in one spouse can be used as an indicator of incident type 2 diabetes in the other spouse.

METHODS

We analysed data from 3649 men and 3478 women from the English Longitudinal Study of Ageing with information on their own and their spouse's diabetes status and cardiometabolic risk factors. We modelled incidence rates and incidence rate ratios with Poisson regression, using spousal diabetes status or cardiometabolic risk factors (i.e. BMI, waist circumference, systolic and diastolic BP, HDL- and LDL-cholesterol and triacylglycerols) as exposures and type 2 diabetes incidence in the index individual as the outcome. Models were adjusted for two nested sets of covariates.

RESULTS

Spousal BMI and waist circumference were associated with incident type 2 diabetes, but with different patterns for men and women. A man's risk of type 2 diabetes increased more steeply with his wife's obesity level, and the association remained statistically significant even after adjustment for the man's own obesity level. Having a wife with a 5 kg/m² higher BMI (30 kg/m² vs 25 kg/m²) was associated with a 21% (95% CI 11%, 33%) increased risk of type 2 diabetes. In contrast, the association between incident type 2 diabetes in a woman and her husband's BMI was attenuated after adjusting for the woman's own obesity level. Findings for waist circumference were similar to those for BMI. Regarding other risk factors, we found a statistically significant association only between the risk of type 2 diabetes in women and their husbands' triacylglycerol levels.

CONCLUSIONS/INTERPRETATION

The main finding of this study is the sex-specific effect of spousal obesity on the risk of type 2 diabetes. Having an obese spouse increases an individual's risk of type 2 diabetes over and above the effect of the individual's own obesity level among men, but not among women. Our results suggest that a couples-focused approach may be beneficial for the early detection of type 2 diabetes and individuals at high risk of developing type 2 diabetes, especially in men, who are less likely than women to attend health checks.

DATA AVAILABILITY

Data were accessed via the UK Data Service under the data-sharing agreement no. 91400 ( https://discover.ukdataservice.ac.uk/catalogue/?sn=5050&type=Data%20catalogue ).

Evaluation of a program of physical activities adapted to the morphological, physiological and body composition parameters of overweight and obese adolescents of the Lukunga sports club of Kinshasa, Democratic Republic of Congo

Objective. To study the effects of regular physical activity on the morphological, physiological and body composition parameters of overweight and obese adolescents. Methods. We conducted an experimental study with30 adolescents divided in two according to their body mass index. The group 1 was composed of overweight subjects with a body mass index between 25-29.9 kg/m2 , and group 2 obese subjects with a body mass index 30 kg/m2 subjected to a program of adapted physical activity associated with a low-calorie nutrition education low in cholesterol and in saturated fatty acids (bad fats), low-fat rich in vegetables, fruits and vitamins for a period of six months. Results. This study reveals that after six months of intervention, overweight subjects significantly decreased waist circumference (82.9 ± 4.2 cm before versus 77.6 ± 4.6 cm after), heart rate (86.8 ± 3.6 beat/min before versus 81.4 ± 3.8 beat/min after), total fat (32.2 ± 1.8% before versus 27.2 ± 1.5% after), visceral fat (16.6 ± 2.3% before versus 11.1 ± 2.5% after), and decreased muscle (15.6 ± 2.7% before versus 19.4 ± 4.1% after), while obese subjects significantly decreased waist circumference (88.9 ± 6.2 cm before versus 85.8 ± 5.9 cm after), visceral fat (17.4 ± 3.2% before versus 14.1 ± 3.1% after), respiratory capacity (61.1 ± 2.7% before versus 65 ± 2.1%). In addition this study reveals that overweight subjects compared to obese subjects more changed their waist circumference (77.6 ± 4.6 cm for overweight versus 85.8 ± 5.9 cm for obese), body mass index (24.9 ± 4.1 kg/m2 for overweight versus 28.8 ± 1.2 kg/m2 for obese), heart rate (81.4 ± 3.8 beat/min for overweight versus 28.8 ± 1.2 beat/min for obese), visceral fat (11.1 ± 2.5% for overweight versus 14.1 ± 3.1% for obese), and muscle (19.4 ± 4.1% for overweight versus 17.1 ± 2.1%). Conclusion. Obese adolescents have by means of regular activity significantly changed their morphological, physiological and body composition parameters of overweight and obese

Effect of different intensities of physical activity on cardiometabolic markers and vascular and cardiac function in adult rats fed with a high-fat high-carbohydrate diet

BACKGROUND

Physical activity (PA) and diet are 2 lifestyle factors that affect cardiometabolic risk. However, data on how a high-fat high-carbohydrate (HFHC) diet influences the effect of different intensities of PA on cardiometabolic health and cardiovascular function in a controlled setting are yet to be fully established. This study investigated the effect of sedentary behavior, light-intensity training (LIT), and high-intensity interval training (HIIT) on cardiometabolic markers and vascular and cardiac function in HFHC-fed adult rats.

METHODS

Twelve-week-old Wistar rats were randomly allocated to 4 groups (12 rats/group): control (CTL), sedentary (SED), LIT, and HIIT. Biometric indices, glucose and lipid control, inflammatory and oxidative stress markers, vascular reactivity, and cardiac electrophysiology of the experimental groups were examined after 12 weeks of HFHC-diet feeding and PA interventions.

RESULTS

The SED group had slower cardiac conduction (p = 0.0426) and greater thoracic aortic contractile responses (p < 0.05) compared with the CTL group. The LIT group showed improved cardiac conduction compared with the SED group (p = 0.0003), and the HIIT group showed decreased mesenteric artery contractile responses compared with all other groups and improved endothelium-dependent mesenteric artery relaxation compared with the LIT group (both p < 0.05). The LIT and HIIT groups had lower visceral (p = 0.0057 for LIT, p = 0.0120 for HIIT) and epididymal fat (p < 0.0001 for LIT, p = 0.0002 for HIIT) compared with the CTL group.

CONCLUSION

LIT induced positive adaptations on fat accumulation and cardiac conduction, and HIIT induced a positive effect on fat accumulation, mesenteric artery contraction, and endothelium-dependent relaxation. No other differences were observed between groups. These findings suggest that few positive health effects can be achieved through LIT and HIIT when consuming a chronic and sustained HFHC diet.

Physical activity and central adiposity in a cohort of African-American adults

Background

Visceral adipose tissue (VAT) is known as an independent predictor of cardiometabolic risk and all-cause mortality, while increased physical activity has been shown to improve cardiometabolic risk. The purpose of the present study was to determine whether or not there is an association between objectively-measured physical activity and VAT in a community-based cohort of African-American adults, a population at higher-than-average risk for cardiometabolic diseases.

Methods

Free-living physical activity was quantified using accelerometry while VAT and abdominal subcutaneous fat were estimated using dual x-ray absorptiometry in a cohort of African Americans, ages 30–50 years, enrolled in the Modeling the Epidemiologic Transition Study. Univariate and multivariate analyses were used to determine the degree of association comparing moderate-to-vigorous physical activity (MVPA), vigorous activity, and sedentary behavior with measures of central adiposity including VAT, subcutaneous fat, and waist circumference.

Results

A total of 271 individuals with complete data were included in the analyses. Women, on average, had significantly more VAT and abdominal subcutaneous fat than men. There were statistically significant inverse univariate correlations between MVPA and measures of abdominal adiposity (−0.30, p < 0.001) and activity counts and adiposity (−0.31, p < 0.001) among both sexes. These significant associations remained after controlling for age, sex, and smoking status; neither alcohol consumption nor employment status were associated with abdominal adiposity. Time in sedentary behavior was not meaningfully associated with central adiposity in either sex (women: −0.02, p = 0.79; men: −0.21, p = 0.04).

Conclusions

To our knowledge, this study is the first to identify significant inverse associations between MVPA and measures of central adiposity among African American adults from a community-based cohort using an objective measure of physical activity and a validated quantitative imaging technique.

Genetic Susceptibility, Change in Physical Activity, and Long-term Weight Gain

Whether change in physical activity over time modifies the genetic susceptibility to long-term weight gain is unknown. We calculated a BMI-genetic risk score (GRS) based on 77 BMI-associated single nucleotide polymorphisms (SNPs) and a body fat percentage (BF%)-GRS based on 12 BF%-associated SNPs in 9,390 women from the Nurses' Health Study (NHS) and 5,291 men from the Health Professionals Follow-Up Study (HPFS). We analyzed the interactions between each GRS and change in physical activity on BMI/body weight change within five 4-year intervals from 1986 to 2006 using multivariable generalized linear models with repeated-measures analyses. Both the BMI-GRS and the BF%-GRS were associated with long-term increases in BMI/weight, and change in physical activity consistently interacted with the BF%-GRS on BMI change in the NHS (P for interaction = 0.025) and HPFS (P for interaction = 0.001). In the combined cohorts, 4-year BMI change per 10-risk allele increment was -0.02 kg/m² among participants with greatest increase in physical activity and 0.24 kg/m² among those with greatest decrease in physical activity (P for interaction < 0.001), corresponding to 0.01 kg versus 0.63 kg weight changes every 4 years (P for interaction = 0.001). Similar but marginal interactions were observed for the BMI-GRS (P for interaction = 0.045). Our data indicate that the genetic susceptibility to weight gain may be diminished by increasing physical activity.

Ten-year change in sedentary behaviour, moderate-to-vigorous physical activity, cardiorespiratory fitness and cardiometabolic risk: independent associations and mediation analysis

Background

We aimed to study the independent associations of 10-year change in sedentary behaviour (SB), moderate-to-vigorous physical activity (MVPA) and objectively measured cardiorespiratory fitness (CRF), with concurrent change in clustered cardiometabolic risk and its individual components (waist circumference, fasting glucose, high-density lipoprotein (HDL) cholesterol, triglycerides and blood pressure). We also determined whether associations were mediated by change in CRF (for SB and MVPA), waist circumference (for SB, MVPA and CRF) and dietary intake (for SB).

Methods

A population-based sample of 425 adults (age (mean±SD) 55.83±9.40; 65% men) was followed prospectively for 9.62±0.52 years. Participants self-reported SB and MVPA and performed a maximal cycle ergometer test to estimate peak oxygen uptake at baseline (2002–2004) and follow-up (2012–2014). Multiple linear regression and the product of coefficients method were used to examine independent associations and mediation effects, respectively.

Results

Greater increase in SB was associated with more detrimental change in clustered cardiometabolic risk, waist circumference, HDL cholesterol and triglycerides, independently of change in MVPA. Greater decrease in MVPA was associated with greater decrease in HDL cholesterol and increase in clustered cardiometabolic risk, waist circumference and fasting glucose, independent of change in SB. Greater decrease in CRF was associated with more detrimental change in clustered cardiometabolic risk and all individual components. Change in CRF mediated the associations of change in SB and MVPA with change in clustered cardiometabolic risk, waist circumference and, only for MVPA, HDL cholesterol. Change in waist circumference mediated the associations between change in CRF and change in clustered cardiometabolic risk, fasting glucose, HDL cholesterol and triglycerides.

Conclusions

A combination of decreasing SB and increasing MVPA, resulting in positive change in CRF, is likely to be most beneficial towards cardiometabolic health.

Independent Associations between Sedentary Time, Moderate-To-Vigorous Physical Activity, Cardiorespiratory Fitness and Cardio-Metabolic Health: A Cross-Sectional Study

We aimed to study the independent associations of sedentary time (ST), moderate-to-vigorous physical activity (MVPA), and objectively measured cardiorespiratory fitness (CRF) with clustered cardio-metabolic risk and its individual components (waist circumference, fasting glucose, HDL-cholesterol, triglycerides and blood pressure). We also investigated whether any associations between MVPA or ST and clustered cardio-metabolic risk were mediated by CRF. MVPA, ST, CRF and individual cardio-metabolic components were measured in a population-based sample of 341 adults (age 53.8 ± 8.9 years; 61% men) between 2012 and 2014. MVPA and ST were measured with the SenseWear pro 3 Armband and CRF was measured with a maximal exercise test. Multiple linear regression models and the product of coefficients method were used to examine independent associations and mediation effects, respectively. Results showed that low MVPA and low CRF were associated with a higher clustered cardio-metabolic risk (β = -0.26 and β = -0.43, both p<0.001, respectively). CRF explained 73% of the variance in the association between MVPA and clustered cardio-metabolic risk and attenuated this association to non-significance. After mutual adjustment for MVPA and ST, CRF was the most important risk factor for a higher clustered cardio-metabolic risk (β = -0.39, p<0.001). In conclusion, because of the mediating role of CRF, lifestyle-interventions need to be feasible yet challenging enough to lead to increases in CRF to improve someone’s cardio-metabolic health.

Prospective associations between sedentary time, physical activity, fitness and cardiometabolic risk factors in people with type 2 diabetes

AIMS/HYPOTHESIS

The aim of this study was to examine the prospective associations between objectively measured physical activity energy expenditure (PAEE), sedentary time, moderate-to-vigorous-intensity physical activity (MVPA), cardiorespiratory fitness (CRF) and cardiometabolic risk factors over 4 years in individuals with recently diagnosed diabetes.

METHODS

Among 308 adults (mean age 61.0 [SD 7.2] years; 34% female) with type 2 diabetes from the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen Detected Diabetes in Primary Care (ADDITION)-Plus study, we measured physical activity using individually calibrated combined heart rate and movement sensing. Multivariable linear regression models were constructed to examine the associations between baseline PAEE, sedentary time, MVPA, CRF and cardiometabolic risk factors and clustered cardiometabolic risk (CCMR) at follow-up, and change in these exposures and change in CCMR and its components over 4 years of follow-up.

RESULTS

Individuals who increased their PAEE between baseline and follow-up had a greater reduction in waist circumference (-2.84 cm, 95% CI -4.84, -0.85) and CCMR (-0.17, 95% CI -0.29, -0.04) compared with those who decreased their PAEE. Compared with individuals who decreased their sedentary time, those who increased their sedentary time had a greater increase in waist circumference (3.20 cm, 95% CI 0.84, 5.56). Increases in MVPA were associated with reductions in systolic blood pressure (-6.30 mmHg, 95% CI -11.58, -1.03), while increases in CRF were associated with reductions in CCMR (-0.23, 95% CI -0.40,-0.05) and waist circumference (-3.79 cm, 95% CI -6.62, -0.96). Baseline measures were generally not predictive of cardiometabolic risk at follow-up.

CONCLUSIONS/INTERPRETATION

Encouraging people with recently diagnosed diabetes to increase their physical activity and decrease their sedentary time may have beneficial effects on their waist circumference, blood pressure and CCMR.

Abdominal obesity as a mediator of the influence of physical activity on insulin resistance in Spanish adults

OBJECTIVE

The aim of the study was to analyze the relationship between moderate-to-vigorous physical activity (MVPA) and insulin resistance (IR) in Spanish adults and to examine whether this relationship is mediated by abdominal obesity (waist circumference - WC).

METHODS

The cross-sectional study included 1162 healthy subjects belonging to the EVIDENT study (mean age 55.0±13.3years; 61.8% women) from six different Spanish provinces. Moderate-to-vigorous physical activity (MVPA) was measured objectively over 7days using Actigraph accelerometers, collecting data in 60-second epochs, and retaining respondents with ≥4 valid days for the analysis. The homeostasis model of assessment (HOMA-IR) was used to determine IR, and its individual components - fasting glucose and insulin - were determined using standard protocols. Linear regression models were fitted according to Baron and Kenny's procedures for mediation analysis.

RESULTS

Fasting insulin and HOMA-IR levels were significantly worse in adults who spent fewer minutes in MVPA (first quartile≤30.1 and 22.7min/day in men and women, respectively) after adjusting for age, sex, smoking habits, drinking habits, accelerometer wear time, sedentary time, and Mediterranean diet adherence. However, when WC was added to the ANCOVA models as a covariate, the effects disappeared. Mediation analysis reported that WC acts as a full mediator in the relationship between MVPA and IR (HOMA-IR and fasting insulin).

CONCLUSION

These findings show that WC plays a pivotal role in the relationship between MVPA and IR, and therefore highlights that decreasing abdominal obesity might be considered as an intermediate outcome for evaluating interventions aimed at preventing diabetes mellitus.

Objectively Measured Daily Steps and Subsequent Long Term All-Cause Mortality: The Tasped Prospective Cohort Study

Background

Self–reported physical activity has been inversely associated with mortality but the effect of objectively measured step activity on mortality has never been evaluated. The objective is to determine the prospective association of daily step activity on mortality among free-living adults.

Methods and Findings

Cohort study of free-living adults residing in Tasmania, Australia between 2000 and 2005 who participated in one of three cohort studies (n = 2 576 total participants). Daily step activity by pedometer at baseline at a mean of 58.8 years of age, and for a subset, repeated monitoring was available 3.7 (SD 1.3) years later (n = 1 679). All-cause mortality (n = 219 deaths) was ascertained by record-linkage to the Australian National Death Index; 90% of participants were followed-up over ten years, until June 2011. Higher daily step count at baseline was linearly associated with lower all-cause mortality (adjusted hazard ratio AHR, 0.94; 95% CI, 0.90 to 0.98 per 1 000 steps; P = 0.004). Risk was altered little by removing deaths occurring in the first two years. Increasing baseline daily steps from sedentary to 10 000 steps a day was associated with a 46% (95% CI, 18% to 65%; P = 0.004) lower risk of mortality in the decade of follow-up. In addition, those who increased their daily steps over the monitoring period had a substantial reduction in mortality risk, after adjusting for baseline daily step count (AHR, 0.39; 95% CI, 0.22 to 0.72; P = 0.002), or other factors (AHR, 0.38; 95% CI, 0.21–0.70; P = 0.002).

Conclusions

Higher daily step count was linearly associated with subsequent long term mortality among free living adults. These data are the first to quantify mortality reductions using an objective measure of physical activity in a free living population. They strongly underscore the importance of physical inactivity as a major public health problem.

Health benefits of cycle ergometer training for older adults over 70: a review

As the number of older adults continues to increase worldwide, more attention is being paid to geriatric health care needs, and successful ageing is becoming an important topic in the medical literature. A preventive approach to the care of older adults is thus a priority in our aging societies. The purpose of this study was to update evidence for the health benefits of cycle ergometer training for older adults over 70. We searched online electronic databases up to September 2014 for original observational and intervention studies on the relationship between cycle ergometer training and health among older patients over 70. Twenty-five studies examined interventions aimed specifically at promoting cycling for older adults over 70. These studies reported a positive effect on the prevention of cardiovascular disease, and a significant improvement in metabolic responses. Improving functional status, muscle strength and cognitive performance are also well established. Overall, this review demonstrates a positive effect of cycle ergometer training with functional benefits and positive health outcomes for older adults over 70. Based on this evidence, clinicians can now encourage older adults to profit from the health benefits of cycle ergometer training to be able to pursue their daily activities independently.

Health benefits of endurance training alone or combined with diet for obese patients over 60: a review

BACKGROUND

The prevalence of obesity is rapidly increasing in older patients and it is ubiquitous in many developed countries. Obesity is related to various negative health outcomes, making it a major public health target for intervention.

PURPOSE

The aim of this study was to explore and summarise the literature that addresses endurance training alone or combined with nutrition interventions to combat obesity in obese patients over age 60.

METHODS

We searched online electronic databases up to September 2014 for original observational and intervention studies published between 1995 and 2014 on the relationship between endurance training alone or combined with a diet in obese patients over 60 regarding health outcomes.

RESULTS

Twenty-six studies examined interventions aimed specifically at promoting endurance training alone or combined with diet for older obese patients over 60. These studies demonstrated a positive effect of this intervention on the primary prevention of cardiovascular disease, and a significant beneficial effect on the lipid profile. Improvement of body composition and insulin sensitivity, and a reduction in blood pressure were also well established.

CONCLUSIONS

Overall, this review demonstrates a positive effect of endurance training alone or combined with diet on health outcomes and metabolic benefits in older adults. Clinicians can now use this evidence to formulate actions to encourage the older obese to profit from the health benefits of endurance training and diet. This will not only help reduce the dramatic increase in the number of older obese but also help prevent sarcopenic obesity, which is a complex challenge for healthcare professionals.

The use of cycling workstations in public places - an observational study

OBJECTIVES

To determine the use of cycling workstations in public places; how long are they used, who uses them, and why do people use them.

STUDY DESIGN

Mixed methods study; observations in combination with questionnaires.

METHODS

Cycling desks with a charging feature (We-bike) at Brussels National Airport and Brussels South railway station were observed. Data about the number of users, time spent using the workstation, cycling and charging behaviour, were collected by observation. Data about sex, age, body mass index (BMI) and the reason of the use, were obtained via a survey.

RESULTS

Approximately three people per hour cycled on the workstation. Mean (SD) cycling time was 15.2 (11.9) minutes and mean (SD) cycling intensity was 2.11 (1.16) on the modified Borg scale. 88% of the users charged a device. About two-thirds of the observed people were male and the majority was between 26 and 45 years old (44%). The average BMI (SD) of the surveyed participants was 24.0 (3.1) kg/m(2), with 26.1% of the participants being overweight. People used the desks because they thought it was fun, relaxing, a good distraction, healthy, good for maintaining shape and/or eco-friendly. However, the majority of the participants (83%) used it because of the charging feature and only one-third of the people would also use the desk if a charging feature was not available.

CONCLUSIONS

Cycling desks at public places are used by approximately three people per hour. The charging feature is an important motivating factor as only one-third of the people would use the cycling workstation if there would not be a charging feature. As this easy-to-use machine brings about a decrease in sedentary behaviour and an increase in energy expenditure, the availability at places accessible to everyone, could contribute to a less sedentary society and could thus contribute to the prevention of diseases and mental problems related to prolonged sitting.

Beneficial effects of training at the anaerobic threshold in addition to pharmacotherapy on weight loss, body composition, and exercise performance in women with obesity

OBJECTIVE

The aim of this study was to determine and compare the effects of weight loss achieved through orlistat therapy alone or a combination of orlistat and an aerobic exercise training program on aerobic fitness and body composition in obese females.

METHODS

Twenty-eight obese patients were randomly assigned to receive 12-week treatment with hypocaloric diet-orlistat or diet-orlistat-exercise. Each participant performed an incremental ramp exercise test every 4 weeks to measure aerobic fitness. Fourteen participants performed continuous exercise (approximately 45 minutes per session) at a work rate corresponding to the anaerobic threshold three times per week.

RESULTS

A decrease in the fat mass to body weight ratio of 3.8% (P=0.006) was observed at the end of the 12 weeks in the orlistat group, while a decrease of 9.5% (P=0.001) was seen in the orlistat-exercise group. Maximal exercise capacity increased by 46.5% in the orlistat-exercise group and by 19.5% in the orlistat group.

CONCLUSION

While orlistat therapy resulted in an improvement in body composition and aerobic fitness at the end of the 12-week period, its combination with exercise training provided improvements in the same parameters within the first 4 weeks of the study. These additional beneficial effects of combining aerobic exercise with orlistat therapy are important with regards to obesity-associated risk factors.

Associations between physical activity and cardiometabolic risk factors assessed in a Southern California health care system, 2010-2012

INTRODUCTION

Risk factors associated with many chronic diseases can be improved through regular physical activity. This study investigated whether cross-sectional associations between physical activity, assessed by the Exercise Vital Sign (EVS), and cardiometabolic risk factors can be detected in clinical settings.

METHODS

We used electronic records from Kaiser Permanente Southern California members (N = 622,897) to examine the association of EVS category with blood pressure, fasting glucose, random glucose, and glycosylated hemoglobin. Adults aged 18 years or older with at least 3 EVS measures between April 2010 and December 2012, without comorbid conditions, and not taking antihypertension or glucose-lowering medications were included. We compared consistently inactive (EVS = 0 min/wk for every measure) with consistently active (EVS ≥150 min/wk) and irregularly active (EVS 1-149 min/wk or not meeting the consistently active or inactive criteria) patients. Separate linear regression analyses were conducted controlling for age, sex, race/ethnicity, body mass index, and smoking status.

RESULTS

Consistently active women had lower systolic (-4.60 mm Hg; 95% confidence interval [CI], -4.70 to -4.44) and diastolic (-3.28 mm Hg; 95% CI, -3.40 to -3.17) blood pressure than inactive women. Active men had lower diastolic blood pressure than inactive men. Consistently active patients (women, -5.27 mg/dL [95% CI, -5.56 to -4.97]; men, -1.45 mg/dL [95% CI, -1.75 to -1.16] and irregularly active patients (women, -4.57 mg/dL [95% CI, -4.80 to -4.34]; men, -0.42 mg/dL [95% CI, -0.66 to -0.19]) had lower fasting glucose than consistently inactive patients. Consistently active and irregularly active men and women also had favorable random glucose and HbA1c compared with consistently inactive patients.

CONCLUSION

Routine clinical physical activity assessment may give health care providers additional information about their patients' cardiometabolic risk factors.

Early onset type 2 diabetes: risk factors, clinical impact and management

Early onset type 2 diabetes mellitus (T2DM) is increasingly prevalent with a significant impact on the individual, healthcare service delivery and planning. The individuals are likely to be obese, lead a sedentary lifestyle, have a strong family history of T2DM, be of black and minority ethnic (BME) origin and come from a less affluent socioeconomic group. They have a heightened risk of developing microvascular and macrovascular complications, often at an earlier stage and with greater frequency than seen in type 1 diabetes. As such, early and aggressive risk factor management is warranted. Early onset T2DM is complex and impacts on service delivery with a need for multidisciplinary care of complications and comorbidities', in addition to adequate educational and psychological support. This review on the impact of early onset T2DM provides the latest insights into this emerging epidemic.

Niacin increased glucose, insulin, and C-peptide levels in sedentary nondiabetic postmenopausal women

The current study examined the effects of niacin and a single bout of aerobic exercise on plasma glucose, insulin, and C-peptide in sedentary, nondiabetic postmenopausal women. As a crossover design, 17 participants underwent four different trials: rest during the no-niacin condition (R), exercise during the no-niacin condition (E), rest during the with-niacin condition (RN), and exercise during the with-niacin condition (EN). All participants took 1,000 mg/day of extended-release niacin for 4 weeks during the with-niacin conditions (RN and EN). The exercise treatment consisted of a single bout of treadmill walking at 60% heart rate reserve until 400 kcal were expended. Blood samples were collected at 24 hours after each trial and analyzed for changes in plasma glucose, insulin, and C-peptide. A two by two analysis of variance was used to examine the changes in dependent variables, and the Bonferroni adjustment was employed as the post hoc test. The level of statistical significance was set at P<0.05. There was no significant interaction between exercise and niacin, nor was there a main effect of exercise for changes in glucose, insulin, or C-peptide. However, there was a significant main effect for niacin as mean glucose, insulin, and C-peptide values significantly increased with niacin; glucose increased 10.6% (P=0.001), from 95.03±10.67 mg/dL to 105.07±13.56 mg/dL; insulin increased 61.8% (P=0.001), from 16.98±12.49 μU/mL to 27.48±14.84 μU/mL; and C-peptide increased 46.1% (P=0.001), from 1.65±0.75 ng/mL to 2.41±0.97 ng/mL. Although niacin was generally well tolerated, given its adverse effects on glucose, insulin, and C-peptide profiles, the use of niacin should be done so with caution and under medical supervision.

Aerobic exercise did not have compensatory effects on physical activity levels in type 2 diabetes patients

Although exercise promotes beneficial effects in diabetic patients, some studies have questioned the degree of their importance in terms of the increase in total energy expenditure. In these studies, the decrease of physical activity levels (PAL) was referred as "compensatory effect of exercise". However, our aim was to investigate whether aerobic exercise has compensatory effects on PAL in type 2 diabetes patients. Eight volunteers (51.1 ± 8.2 years) were enrolled in a supervised exercise programme for 8 weeks (3 d · wk(-1), 50-60% of VO2 peak for 30-60 min). PAL was measured using tri-axial accelerometers in the 1st, 8th and 12th weeks. Biochemical tests, cardiorespiratory fitness, anthropometric assessment and body composition were measured in the 2nd and 11th weeks. Statistical analysis was performed using non-parametric tests (Friedman and Wilcoxon, P < 0.05). We found no significant differences in PAL between intervention periods, and participants spent the majority of their awake time in sedentary activities. However, the exercise programme generated a significant 14.8% increase in VO2 peak and a 15% reduction in fructosamine. The exercise programme had no compensatory effects on PAL in type 2 diabetes patients, but improved their cardiorespiratory fitness and glycaemic control.

Which activity monitor to use? Validity, reproducibility and user friendliness of three activity monitors

BACKGROUND

Health is associated with amount of daily physical activity. Recently, the identification of sedentary time as an independent factor, has gained interest. A valid and easy to use activity monitor is needed to objectively investigate the relationship between physical activity, sedentary time and health. We compared validity and reproducibility of physical activity measurement and posture identification of three activity monitors, as well as user friendliness.

METHODS

Healthy volunteers wore three activity monitors simultaneously: ActivPAL3, ActiGraphGT3X and CAM. Data were acquired under both controlled (n = 5) and free-living conditions (n = 9). The controlled laboratory measurement, that included standardized walking intensity and posture allocation, was performed twice. User friendliness was evaluated with a questionnaire. Posture classification was compared with direct observation (controlled measurement) and with diaries (free living). Accelerometer intensity accuracy was tested by correlations with walking speed. User friendliness was compared between activity monitors.

RESULTS

Reproducibility was at least substantial in all monitors. The difference between the two CAM measurements increased with walking intensity. Amount of correct posture classification by ActivPAL3 was 100.0% (kappa 0.98), 33.9% by ActiGraphGT3X (kappa 0.29) and 100.0% by CAM (kappa 0.99). Correlations between accelerometer intensity and walking speed were 0.98 for ActivPAL3, 1.00 for ActiGraphGT3X and 0.98 for CAM. ICCs between activity monitors and diary were 0.98 in ActivPAL3, 0.59 and 0.96 in ActiGraphGT3X and 0.98 in CAM. ActivPAL3 and ActiGraphGT3X had higher user friendliness scores than the CAM.

CONCLUSIONS

The ActivPAL3 is valid, reproducible and user friendly. The posture classification by the ActiGraphGT3X is not valid, but reflection of walking intensity and user friendliness are good. The CAM is valid; however, reproducibility at higher walking intensity and user friendliness might cause problems. Further validity studies in free living are recommended.

Association between change in daily ambulatory activity and cardiovascular events in people with impaired glucose tolerance (NAVIGATOR trial): a cohort analysis

BACKGROUND

The extent to which change in physical activity can modify the risk of cardiovascular disease in individuals at high cardiovascular risk is uncertain. We investigated whether baseline and change in objectively-assessed ambulatory activity is associated with the risk of a cardiovascular event in individuals at high cardiovascular risk with impaired glucose tolerance.

METHODS

We assessed prospective data from the NAVIGATOR trial involving 9306 individuals with impaired glucose tolerance who were recruited in 40 countries between January, 2002, and January, 2004. Participants also either had existing cardiovascular disease (if age ≥50 years) or at least one additional cardiovascular risk factor (if age ≥55 years). Participants were followed-up for cardiovascular events (defined as cardiovascular mortality, non-fatal stroke, or myocardial infarction) for 6 years on average and had ambulatory activity assessed by pedometer at baseline and 12 months. Adjusted Cox proportional hazard models quantified the association of baseline and change in ambulatory activity (from baseline to 12 months) with the risk of a subsequent cardiovascular event, after adjustment for each other and potential confounding variables. This study is registered with ClinicalTrials.govNCT00097786.

FINDINGS

During 45,211 person-years follow-up, 531 cardiovascular events occurred. Baseline ambulatory activity (hazard ratio [HR] per 2000 steps per day 0·90, 95% CI 0·84-0·96) and change in ambulatory activity (0·92, 0·86-0·99) were inversely associated with the risk of a cardiovascular event. Results for change in ambulatory activity were unaffected when also adjusted for changes in body-mass index and other potential confounding variables at 12 months.

INTERPRETATION

In individuals at high cardiovascular risk with impaired glucose tolerance, both baseline levels of daily ambulatory activity and change in ambulatory activity display a graded inverse association with the subsequent risk of a cardiovascular event.

FUNDING

Novartis Pharmaceuticals.

Top 10 research questions related to body composition

An understanding of body composition is crucial to understanding human health, disease, and function. Research in body composition has focused on the development of assessment methods, description of normal changes in body composition with growth and development and aging, and the changes that occur in body composition in response to challenges ranging from illness to planned interventions. Each focus is significant, and in a sense, they are interdependent, because technological advances allow more sophisticated questions to be addressed, which in turn drives the development of better methods. Significant advances have been made in each area, although perhaps surprisingly basic questions remain. For example, growth trajectories are often estimated from cross-sectional data, given the resources needed for long-term observational studies, and thus, longitudinal descriptive data are still needed. Along with advances in laboratory methods, development of field methods remains relevant for screening and clinical practice. Despite recognition of wide interindividual differences in intervention response, average outcomes continue to be emphasized. With technological advances, it is now possible to examine genetic along with nongenetic factors that underlie changes in body composition, and these techniques need to be applied in long-term, well-controlled trials. In this article, we review 10 key questions in related areas in which research is needed to continue to advance the field.

Effect of a short-term exercise program on glycemic control measured by fructosamine test in type 2 diabetes patients

BACKGROUND

Glycated hemoglobin (A1C) and Fasting Plasma Glucose (FPG) are the two monitoring blood glucose tests most frequently used. However, both methods are shown to be insensitive to detect glycemic variations in short duration periods. Therefore, we aimed to assess the effect of a short-term exercise program on glycemic levels measured by fructosamine concentrations in type 2 diabetes patients.

METHODS

Eight volunteers (51.1 ± 8.2 years) underwent a supervised exercise program during eight weeks (3 d.wk-1, 50-60% of VO2 peak for 30-60 minutes). The body composition, VO2 peak, A1C, FPG, fructosamine and capillary blood glucose (CBG) were evaluated. We used ANOVA - One Way for repeated measures followed by Tukey post-hoc test and paired t test. P values <0.05 were considered significant.

RESULTS

We found statistical differences on the concentrations of fructosamine, VO2 peak and CBG. However, A1C and FPG showed no statistical difference. Fructosamine declined by 15% (57 μmol/L) between the beginning and the end of the study. Individually, 50% of the sample reached the reference values for the normality in fructosamine test. VO2 peak increased by 14.8% (3.8 ml.kg-1.min-1) and CBG decreased on an average of 34.4% (69.3 mg/dL).

CONCLUSIONS

Fructosamine test is effective in the evaluation of glucose with type 2 diabetes patients when undergoing a short exercise program, alternatively to the traditional A1C and FPG assessment. Our results are relevant in clinical practice, because the significant improvement in glycemic status can help to evaluate the inclusion of exercise as adjunct therapy to replace the prescription of additional drugs in poorly controlled patients.

Assessment of the impact of a workplace intervention to reduce prolonged occupational sitting time

We aim to provide a better picture of the outcomes associated with implementing a nonpurposeful, physical activity, e-health intervention in a professional workplace. There is a need for health professionals to evaluate physical-activity-based workplace health interventions with a full range of measures. Using a social ecological model as a basis, we identify a range of subjective outcomes from 15 interviews of a cross section of participants. We document that not only did participants report a range of positive outcomes across multiple systems of influence, but they experienced some negative outcomes because of disruption to work flow and a changing of work habit. We conclude that using subjective evaluations provides a comprehensive picture of the factors that influence judgments of the efficacy of a workplace health intervention.

Physical activity energy expenditure is associated with 2-h insulin independently of obesity among Inuit in Greenland

AIMS

Indigenous populations throughout the Arctic are experiencing a rapid increase in the prevalence of obesity and type 2 diabetes. The role of physical activity in relation to glucose metabolism in Arctic populations is not well studied. We examined the association between objectively measured physical activity energy expenditure (PAEE) and glucose metabolism in a population-based study of adult Inuit in Greenland.

METHODS

Cross-sectional data were collected by combined accelerometry and heart rate monitoring (ACC+HR) among Inuit (18+ years) in Greenland during 2005-2010 (n=1545). PAEE was calculated and the associations with fasting glucose, 2-h glucose, fasting insulin, 2-h insulin concentrations and body composition were analysed by linear regression.

RESULTS

An inverse association between PAEE and fasting insulin, 2-h insulin, 2-h glucose, fat percentage, BMI and waist circumference (WC) was found after adjustments by age and sex. Only the association between PAEE and 2-h insulin remained significant after adjustment by WC (P=0.01), most pronounced at low levels of PAEE indicating a threshold around 35-40kJ/kg/day. No overall linear trend was found for fasting glucose and 2-h glucose.

CONCLUSIONS

This population-based study showed that PAEE was associated with 2-h insulin independently of obesity in an inverse dose-response relation. Insufficient physical activity may contribute to impaired glucose tolerance through a pathway including alterations in obesity and fat distribution. Both obesity and low levels of PAEE may be important contributing risk factors for the increasing prevalence of type 2 diabetes mellitus among Inuit in Greenland, but additional risk factors should be examined in this indigenous population.

Heritability of objectively assessed daily physical activity and sedentary behavior

BACKGROUND

Twin and family studies that estimated the heritability of daily physical activity have been limited by poor measurement quality and a small sample size.

OBJECTIVE

We examined the heritability of daily physical activity and sedentary behavior assessed objectively by using combined heart rate and movement sensing in a large twin study.

DESIGN

Physical activity traits were assessed in daily life for a mean (± SD) 6.7 ± 1.1 d in 1654 twins from 420 monozygotic and 352 dizygotic same-sex twin pairs aged 56.3 ± 10.4 y with body mass index (in kg/m(2)) of 26.1 ± 4.8. We estimated the average daily movement, physical activity energy expenditure, and time spent in moderate-to-vigorous intensity physical activity and sedentary behavior from heart rate and acceleration data. We used structural equation modeling to examine the contribution of additive genetic, shared environmental, and unique environmental factors to between-individual variation in traits.

RESULTS

Additive genetic factors (ie, heritability) explained 47% of the variance in physical activity energy expenditure (95% CI: 23%, 53%) and time spent in moderate-to-vigorous intensity physical activity (95% CI: 29%, 54%), 35% of the variance in acceleration of the trunk (95% CI: 0%, 44%), and 31% of the variance in the time spent in sedentary behavior (95% CI: 9%, 51%). The remaining variance was predominantly explained by unique environmental factors and random error, whereas shared environmental factors played only a marginal role for all traits with a range of 0-15%.

CONCLUSIONS

The between-individual variation in daily physical activity and sedentary behavior is mainly a result of environmental influences. Nevertheless, genetic factors explain up to one-half of the variance, suggesting that innate biological processes may be driving some of our daily physical activity.

Effects of a playground marking intervention on school recess physical activity in French children

OBJECTIVE

Playground interventions offer an opportunity to enhance school recess physical activity. We aimed to assess the effects of playground marking on objectively measured school recess physical activity in French children.

METHODS

Participants were four hundred and twenty children (6-11years old) from 4 primary schools in Nord-Pas de Calais, France. Children's physical activity (PA) was measured with a uniaxial accelerometer twice a day (morning and afternoon recess) during a 4-day school week in April and May 2009. Two experimental schools (EG) received a recess-based intervention (playground markings) and two others served as controls (CG). Percentage of time spent on the following intensities of physical activity during school recess was measured before and after intervention: sedentary (SED), light physical activity (LPA), moderate physical activity (MPA), vigorous physical activity (VPA), very high physical activity (VHPA) and moderate-to-vigorous physical activity (MVPA).

RESULTS

At baseline, school recess PA among children from CG was significantly (p<0.001) higher than that among EG children. No interaction was observed between the recess-based intervention and gender. After the intervention, the EG spent significantly (p<0.05) more time in MPA, VPA and MVPA with a concomitant significant decrease in SED (p<0.05) compared to baseline, while the PA in CG remained unchanged.

CONCLUSION

Painted playground markings had a positive short-term effect on school recess physical activity levels.

Concurrent physical activity modifies the association between n3 long-chain fatty acids and cardiometabolic risk in midlife adults

Greater consumption of n3 (ω3) polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can reduce risk for cardiovascular disease events, yet their effects on metabolic risk factors and diabetes remain unclear. This cross-sectional study used a community volunteer sample to test whether the associations between n3 fatty acids and cardiometabolic risk vary as a function of physical activity. Participants were 344 generally healthy adults, 30-54 y of age, not taking fish oil supplements or confounding medications. Serum phospholipid EPA and DHA were used together (EPA+DHA) as a biomarker of n3 fatty acid exposure. Cardiometabolic risk was calculated as a continuous measure based on standardized distributions of blood pressure, waist circumference, HDL cholesterol, triglycerides, glucose, and a simple count of risk factors. Insulin resistance was estimated from the homeostatic model assessment. Physical activity was found to predict cardiometabolic risk (P ≤ 0.02) and insulin resistance (P ≤ 0.02) and to moderate the association between EPA+DHA and both cardiometabolic risk (P-interaction ≤ 0.02) and insulin resistance (P-interaction ≤ 0.02). Specifically, higher EPA+DHA was associated with lower cardiometabolic risk and insulin resistance in persons engaged in regular physical activity but not in relatively inactive individuals. These findings were noted in several components of cardiometabolic risk, in men and women separately, and in models adjusted for overall diet quality. In midlife adults, habitual physical activity may be necessary to unmask the salutary effects of n3 fatty acids on cardiometabolic risk and insulin resistance.

Associations of cardiorespiratory fitness, physical activity, and obesity with metabolic syndrome in Hong Kong Chinese midlife women

BACKGROUND

Several studies have simultaneously examined physical activity (PA) and cardiorespiratory fitness (CRF) with metabolic syndrome (MS). However, the independent roles of both PA and CRF with MS are less firmly established. The combined contributions of PA and CRF with MS are less studied, particularly among Chinese women. There is uncertainty over the extent to which metabolically healthy but overweight/obese individuals have a higher CRF level.

METHODS

The sample included 184 Chinese women aged 55 to 69 years with available metabolic data and lifestyle factors. PA was assessed by self-reported questionnaire; CRF was assessed by maximal oxygen consumption (VO2max) during a symptom-limited maximal exercise test on a cycle ergometer. Metabolically healthy/abnormal was defined on the basis of absence or presence of MS. Overweight was defined as a body mass index (BMI) of ≥ 23 kg/m2 and obese was defined as a BMI of ≥ 25 kg/m2.

RESULTS

The prevalence of MS was 21.7%. PA was inversely associated with the prevalence of MS after adjustment for age, BMI, and dietary total calories intake, but the association was eliminated after further adjustment for CRF. CRF was inversely associated with the prevalence of MS independent of age, BMI, and dietary total calories intake, and the association remained significant after further adjustment for PA. In the PA and CRF combined analysis, compared with those in the lowest tertile of PA (inactive) and lowest tertile of CRF (unfit), the OR (95%CI) of having MS was 0.31 (0.09-1.06) for subjects in the higher tertiles (2nd-3rd) of PA (active) but were unfit, 0.23 (0.06-0.88) for subjects who were inactive but in the higher tertiles (2nd-3rd) of CRF (fit), and 0.14 (0.04-0.45) for subjects who were active and fit. Metabolically healthy but overweight/obese subjects had a higher CRF level than their metabolically abnormal and overweight/obese peers. However, the difference did not reach statistically significance.

CONCLUSIONS

CRF has greater association with the prevalence of MS compared with PA in Chinese midlife women. The interrelationships between CRF, obesity, and MS needs further study.

Energy balance and obesity: a UK perspective on the gluttonyv.sloth debate

Obesity in the UK was assumed to have developed against a population decline in physical activity, with health messages focused on diet and exercise prevention strategies. Doubly-labelled water (DLW) studies of energy expenditure have indicated the alternative scenario that the increased obesity prevalence reflects excessive food energy intake with physical activity levels unchanged. This analysis is questionable, deriving in part from a weakness of the DLW methodology in identifying changing physical activity levels within populations of increasing body weight. This has resulted in an underestimation of the reduction in physical activity in the overweight and obese, as revealed by direct studies of such behaviour. Furthermore, a close examination of food energy supply, household food purchases and individual food energy consumption since 1955, in relation to likely estimates of current intakes indicated by simple modelling of predicted energy expenditure, identifies: (a) food energy supply as markedly overestimating energy intakes; (b) individual food energy consumption as markedly underestimating energy intakes; and (c) household food purchase data as the closest match to predicted current food energy intakes. Energy intakes indicated by this latter method have fallen by between 20 to 30 %, suggesting comparable falls in physical activity. Although unequivocal evidence for a matching UK trend in falling physical activity is limited, as is evidence that obesity follows reductions in physical activity, such a link has been recently suggested in a large prospective study in adolescents. Thus, for the UK, obesity has developed within a ‘move less–eat somewhat less but still too much’ scenario. A focus on both diet and exercise should remain the appropriate public health policy.

Daily physical activity predicts degree of insulin resistance: a cross-sectional observational study using the 2003-2004 National Health and Nutrition Examination Survey

Background

This study examined the independent association of objectively measured physical activity on insulin resistance while controlling for confounding variables including: cardiorespiratory fitness, adiposity, sex, age, and smoking status.

Methods

Data were obtained from National Health and Nutrition Examination Survey 2003–2004, a cross-sectional observational study conducted by the National Center for Health Statistics of the Centers for Disease Control that uses a stratified, multistage probability design to obtain a nationally representative sample of the U.S. population. The analysis included 402 healthy U.S. adults with valid accelerometer, cardiorespiratory fitness, and fasting plasma glucose and insulin concentrations. After controlling for relevant confounding variables we performed a multiple linear regression to predict homeostatic model of insulin resistance (HOMA-IR) based on average daily minutes of moderate-to-vigorous physical activity (MVPA).

Results

In our bivariate models, MVPA, cardiorespiratory fitness and body fat percentage were all significantly correlated with log HOMA-IR. In the complete model including MVPA and relevant confounding variables, there were strong and significant associations between MVPA and log HOMA-IR (β= −0.1607, P=0.004). In contrast the association between cardiorespiratory fitness and log HOMA-IR was not significant.

Conclusion

When using an objective measure of physical activity the amount of time engaged in daily physical activity was associated with lower insulin resistance, whereas higher cardiorespiratory fitness was not. These results suggest that the amount of time engaged in physical activity may be an important determinant for improving glucose metabolism.

Sedentary behavior: target for change, challenge to assess

Sedentary behavior is not a new topic, but trying to examine the direct links between sedentary behavior and health outcomes, independent of time spent in moderate- and vigorous-intensity physical activity, is a relatively new addition to the relationships between physical activity and health. Defining sedentary behavior as a risk factor and target for intervention opens up novel avenues for disease prevention and health promotion. The relationship between sedentary behavior and obesity is complex and not well understood, but the increased risk of disease due to sedentary behavior may be even greater in obese patients. Objective measurement of sedentary behavior is an important link in being able to understand the real effects of being sedentary, and a few measurement devices are described. Interventions targeting sedentary behavior should reduce total sedentary time, break long bouts of sitting with intermittent activity and encourage light-intensity activity throughout the day. New technologies can both measure and deliver an intervention aimed at reducing sitting time, the most common category of sedentary behavior. An optimal activity profile will include minimal amounts of sedentary behavior, in addition to regular physical activity and healthy sleep patterns.

Diet, fitness and metabolic syndrome--the DR's EXTRA study

BACKGROUND AND AIMS

To study the independent and combined associations of diet and cardiorespiratory fitness with the prevalence of the metabolic syndrome (MetS).

METHODS AND RESULTS

We studied a population-based random sample of 663 men and 671 women 57-78 years of age at baseline of an ongoing randomised controlled trial. Based on a 4-day food record a diet score was created according to goals achieved (vegetables ≥400 g/day, fish ≥2 servings/week, fibre ≥14 g/1000 kcal, saturated fat <10 E%/day). Cardiorespiratory fitness was measured as maximal oxygen uptake (VO(2 max)) in a maximal symptom-limited bicycle ergometer test. MetS was defined by the National Cholesterol Education Program criteria. The lowest prevalence of MetS (5%) was observed among individuals in the highest VO(2 max) tertile and achieving 3-4 dietary goals. The highest prevalence (55%) was observed among those in the lowest VO(2 max) tertile and achieving none of the dietary goals. Among individuals in the highest VO(2 max) tertile, the odds ratio of having MetS was 0.04 (95% CI 0.02-0.10) for those achieving 3-4 dietary goals, 0.07 (0.04-0.14) for those achieving 1-2 dietary goals, and 0.16 (0.07-0.37) for those achieving none of the dietary goals compared with individuals in the lowest VO(2 max) tertile and achieving none of the goals after adjustment for confounding factors.

CONCLUSION

Healthy diet and higher levels of cardiorespiratory fitness are associated with a reduced risk of having MetS. However, fitness seems to have a stronger association with MetS than diet.

Population heterogeneity in trajectories of midlife blood pressure

BACKGROUND

We investigated whether there are subgroups with different underlying (latent) trajectories of midlife systolic blood pressure (BP), diastolic BP, and pulse pressure in a UK cohort.

METHODS

Data are from 1840 men and 1819 women with BP measured at ages 36, 43, and 53 years. We used unconditional growth mixture models to test for the presence of latent trajectory classes. Extracted classes were described in terms of a number of known lifetime risk factors, and linked to the risk of undiagnosed angina (Rose questionnaire) at age 53 years.

RESULTS

In both sexes for systolic BP, diastolic BP, and pulse pressure, there was a large "normative" class (>90% of the sample) characterized by gentle annual increases (eg, an increase in male systolic BP of 0.9 mm Hg/year [95% confidence interval = 0.9 to 1.0]), with a smaller class for whom the rate of increase was high (eg, an increase in male systolic BP of 3.1 mm Hg/year [2.8 to 3.4]). In women, there was an additional class for whom BP was high at age 36 and remained high. Persons in the "normative" classes were, on average, heavier at birth and taller at age 7 years, had a lower midlife body mass index, and were less likely to be on antihypertensive medication compared with those in other classes. Among those with no diagnosed cardiovascular disease, those in the classes with more strongly increasing systolic BP and pulse pressure were at greatest risk of angina.

CONCLUSION

Our study suggests that in midlife the majority of the population have a gentle underlying increase in BP, but that there also exists an important subgroup in whom BP increases much more markedly. These classes may be useful for identifying those most at risk for cardiovascular disease.

Leisure time and occupational physical activity in relation to obesity and insulin resistance: a population-based study from the Skaraborg Project in Sweden

The objective was to study obesity and insulin resistance in relation to leisure time physical activity (LTPA) and occupational physical activity (OPA) in a Swedish population, with particular focus on sex differences. Using a cross-sectional design, waist circumference, body mass index (BMI), glucose/insulin metabolism, blood pressure, heart rate, self-reported education, smoking, alcohol consumption, LTPA, and OPA were assessed in 1745 men and women (30-74 years) randomly chosen from 2 municipalities in southwestern Sweden. In both men and women, LTPA was inversely associated with BMI, waist circumference, and the homeostasis model assessment of insulin resistance (HOMA-IR), respectively. These associations remained statistically significant after adjustments for age, OPA, education, alcohol consumption, smoking, and study area, and also for BMI in the analyses concerning waist circumference and HOMA-IR. A statistically significant interaction term (P = .030), adjusted for multiple confounders, revealed a stronger association between LTPA and HOMA-IR in women compared with men. Occupational physical activity was positively associated with BMI (P < .001), waist circumference (P < .001), and HOMA-IR (P = .001), however, only in women. These associations remained when adjusting for multiple confounders. The sex differences were confirmed by statistically significant interaction terms between sex and OPA in association with BMI, waist circumference, and HOMA-IR, respectively. The observed sex differences regarding the strength of the association between LTPA and insulin resistance, and the positive association between OPA and obesity and insulin resistance found solely in women, warrant further investigation. Although exploration of the metabolic effects of OPA appears to be needed, thorough measurement of potential confounders is also vital to understand contextual effects.