Effects of reducing sedentary behavior on cardiorespiratory fitness in adults with metabolic syndrome: A 6-month RCT

Maximal Oxygen Consumption Is Negatively Associated with Fat Mass in Facioscapulohumeral Dystrophy

Facioscapulohumeral dystrophy (FSHD) leads to progressive changes in body composition such as loss of muscle mass and increase in adiposity. In healthy subjects, anthropometric parameters are associated with the maximum volume of oxygen consumed per minute (VO2max), which is a health and function indicator in several populations of subjects, both healthy and pathological. Since VO2max can be difficult to test in patients with FSHD due to exercise intolerance, the identification of associated anthropometric parameters could provide new easily obtainable elements for the patients' clinical stratification. The aim of this study was to evaluate whether anthropometric and body composition parameters are associated with VO2max in patients with FSHD. A total of 22 subjects with a molecular genetics-based diagnosis of FSHD (6 females, 16 males, mean age of 35.18 years) were recruited for the study. VO2max was measured by cardiopulmonary exercise tests (CPETs) on a cycle ergometer, utilizing a step incremental technique (15 Watts (W) every 30 s). Weight (Kg) and height (m) were obtained and utilized to calculate body mass index (BMI). Body composition parameters (fat mass (FM), fat free mass (FFM), and body cell mass (BCM)) were obtained by bioelectrical impedance analysis (BIA). Significant negative associations were found between VO2max and FM (Spearman correlation coefficient (SCC) -0.712), BMI (SCC -0.673), age (SCC -0.480), and weight (SCC -0.634), unlike FFM and BCM. Our results indicate that FM, BMI, age, and body weight are negatively associated with VO2max in patients with FSHD. This evidence may help practitioners to better stratify patients with FSHD.

Effects of reduced sedentary time on resting, exercise and post-exercise blood pressure in inactive adults with metabolic syndrome - a six-month exploratory RCT

Evidence on the long-term effects of reducing sedentary behaviour (SB) on blood pressure (BP) is scarce. Therefore, we performed a sub-analysis of the BP effects of a six-month intervention that aimed at reducing SB by 1 h/day and replacing it with non-exercise activities. Sixty-four physically inactive and sedentary adults with metabolic syndrome (58% female, 58 [SD 7] years, BP 143/88 [16/9] mmHg, SB 10 [1] h/day) were randomised into intervention (INT, n = 33) and control (CON, n = 31) groups. Resting BP and BP at each stage during and after a graded maximal bicycle ergometer test were measured before and after the intervention. SB, standing, moderate-to-vigorous physical activity (MVPA), and light physical activity (LPA) were measured in six-second intervals at baseline and during the whole six-month intervention using hip-worn accelerometers. The analyses were adjusted for BP medication status. The intervention resulted in a 40 min/day reduction in SB and concomitant 20 min/day increase in MVPA. Resting systolic BP was lower in the CON group before and after the intervention. No group x time interactions were observed in resting BP or BP during exercise at submaximal or maximal intensities, or during recovery. The changes in LPA and MVPA were inversely correlated with the changes in BP during light-to-moderate intensity exercise. An intervention that resulted in a 40 min/day reduction in SB for six months was not sufficient at influencing BP at rest, during or after exercise in adults with metabolic syndrome. However, successfully increasing LPA or MVPA might lower BP during light-to-moderate-intensity activities.

Sedentary time associates detrimentally and physical activity beneficially with metabolic flexibility in adults with metabolic syndrome

Metabolic flexibility (MetFlex) describes the ability to respond and adapt to changes in metabolic demand and substrate availability. The relationship between physical (in)activity and MetFlex is unclear. This study aimed to determine whether sedentary time, physical activity (PA), and cardiorespiratory fitness associate with MetFlex. Sedentary time, standing, and PA were measured with accelerometers for 4 weeks in 64 sedentary adults with metabolic syndrome [37 women, 27 men; 58.3 (SD 6.8) years]. Fitness (V̇o2max; mL·kg-1·min-1) was measured with graded maximal cycle ergometry. MetFlex was assessed with indirect calorimetry as the change in respiratory exchange ratio (ΔRER) from fasting to insulin stimulation with hyperinsulinemic-euglycemic clamp and from low-intensity to maximal exercise. Carbohydrate (CHOox) and fat oxidation (FATox) were calculated from respiratory gases. High sedentary time associated with higher fasting RER [β = 0.35 (95% confidence interval: 0.04, 0.67)], impaired insulin-stimulated MetFlex (ΔRER) [β=-0.41 (-0.72, -0.09)], and lower fasting FATox [β=-0.36 (-0.67, -0.04)]. Standing associated with lower fasting RER [β=-0.32 (-0.62, -0.02)]. Higher standing time and steps/day associated with higher fasting FATox [β = 0.31 (0.01, 0.61), and β = 0.26 (0.00, 0.53)]. Light-intensity and total PA associated with better insulin-stimulated MetFlex [β = 0.33 (0.05, 0.61)], and β = 0.33 (0.05, 0.60)]. Higher V̇o2max associated with higher CHOox during maximal exercise [β = 0.81 (0.62, 1.00)], as well as during insulin stimulation [β = 0.43 (0.13, 0.73)]. P values are less than 0.05 for all associations. Sedentary time and PA associate with MetFlex. Reducing sitting and increasing PA of even light intensity might aid in the prevention of metabolic diseases in risk populations through their potential effects on energy metabolism.NEW & NOTEWORTHY High accelerometer-assessed sedentary time associates with metabolic inflexibility measured during hyperinsulinemic-euglycemic clamp in adults with metabolic syndrome, and more light-intensity and total physical activity associate with more metabolic flexibility. Physical activity behaviors may thus play an important role in the regulation of fuel metabolism. This highlights the potential of reduced sedentary time and increased physical activity of any intensity to induce metabolic health benefits and help in disease prevention in risk populations.

Measurement of Sedentary Behavior-The Outcomes of the Angle for Posture Estimation (APE) Method

Hip-worn accelerometers are commonly used to assess habitual physical activity, but their accuracy in precisely measuring sedentary behavior (SB) is generally considered low. The angle for postural estimation (APE) method has shown promising accuracy in SB measurement. This method relies on the constant nature of Earth's gravity and the assumption that walking posture is typically upright. This study investigated how cardiorespiratory fitness (CRF) and body mass index (BMI) are related to APE output. A total of 3475 participants with adequate accelerometer wear time were categorized into three groups according to CRF or BMI. Participants in low CRF and high BMI groups spent more time in reclining and lying postures (APE ≥ 30°) and less time in sitting and standing postures (APE < 30°) than the other groups. Furthermore, the strongest partial Spearman correlation with CRF (r = 0.284) and BMI (r = -0.320) was observed for APE values typical for standing. The findings underscore the utility of the APE method in studying associations between SB and health outcomes. Importantly, this study emphasizes the necessity of reserving the term "sedentary behavior" for studies wherein the classification of SB is based on both intensity and posture.

Relationship between rest-activity rhythms and cardiorespiratory fitness in middle-aged workers: a cross-sectional study with non-parametric analysis using accelerometers worn on the thigh

BACKGROUND

Rest-activity rhythms are directly related to health risks, but there are limited objective methods to assess them. This study aimed to investigate the relationship between rest-activity rhythms and cardiorespiratory fitness (CRF) in middle-aged workers.

METHODS

Peak oxygen uptake was measured on a treadmill to assess CRF in 254 middle-aged workers who were divided into low, medium, and high-CRF groups based on tertiles. Participants were asked to wear an accelerometer (activPAL) on their thighs for 1 week, and the logarithmically transformed acceleration data were used for the analysis of a 24-hour rest-activity rhythm. Sex, age, body mass index, occupation, smoking status, and alcohol consumption were used as covariates in Model 1, with Model 2 also including walking count on non-workdays. Repeated measures analysis of variance was used to compare time course of rest-activity rhythms changes on workdays between groups, and post-hoc tests were conducted using Bonferroni's correlation.

RESULTS

Higher CRF correlated with increased physical activity. In model 1, higher CRF showed improved interdaily stability, but the significant difference disappeared in model 2 after adjusting for non-workday walking counts. A time-course group comparison showed that the high group had significantly higher activity levels than those of the low group from 6:00 to 8:59 and 17:00 to 17:59 and the medium group from 6:00 to 7:59 and 19:00 to 19:59.

CONCLUSIONS

Workers who have better rest-activity rhythms and engage in higher levels of physical activity on workdays tend to have higher CRF levels. Regular daily routines, influenced by physical activity during holidays, can positively impact cardiopulmonary endurance.