The association between seven-day objectively measured habitual physical activity and 24 h ambulatory blood pressure: the SABPA study

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.

Mediterranean lifestyle index and 24-h systolic blood pressure and heart rate in community-dwelling older adults

Specific foods, nutrients, dietary patterns, and physical activity are associated with lower blood pressure (BP) and heart rate (HR), but little is known about the joint effect of lifestyle factors captured in a multidimensional score. We assessed the association of a validated Mediterranean-lifestyle (MEDLIFE) index with 24-h-ambulatory BP and HR in everyday life among community-living older adults. Data were taken from 2,184 individuals (51% females, mean age: 71.4 years) from the Seniors-ENRICA-2 cohort. The MEDLIFE index consisted of 29 items arranged in three blocks: 1) Food consumption; 2) Dietary habits; and 3) Physical activity, rest, and conviviality. A higher MEDLIFE score (0-29 points) represented a better Mediterranean lifestyle adherence. 24-h-ambulatory BP and HR were obtained with validated oscillometric devices. Analyses were performed with linear regression adjusted for the main confounders. The MEDLIFE-highest quintile (vs Q1) was associated with lower nighttime systolic BP (SBP) (-3.17 mmHg [95% CI: -5.25, -1.08]; p-trend = 0.011), greater nocturnal-SBP fall (1.67% [0.51, 2.83]; p-trend = 0.052), and lower HR (-2.04 bpm [daytime], -2.33 bpm [nighttime], and -1.93 bpm [24-h]; all p-trend < 0.001). Results were similar for each of the three blocks of MEDLIFE and by hypertension status (yes/no). Among older adults, higher adherence to MEDLIFE was associated with lower nighttime SBP, greater nocturnal-SBP fall, and lower HR in their everyday life. These results suggest a synergistic BP-related protection from the components of the Mediterranean lifestyle. Future studies should determine whether these results replicate in older adults from other Mediterranean and non-Mediterranean countries.

The Role of Physical Activity Status in the Relationship between Obesity and Carotid Intima-Media Thickness (CIMT) in Urban South African Teachers: The SABPA Study

Globally, the prevalence of physical inactivity and obesity are on the rise, which may increase carotid intima-media thickness (CIMT) as a marker of subclinical atherosclerosis. This study assessed the association between physical activity (PA), obesity, and CIMT. A cross-sectional study design was used, including a sub-sample (n = 216) of teachers who participated in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SAPBA) study. Measurements included the following: physical activity status (measured with ActiHeart devices over 7 consecutive days), body mass index (BMI), waist circumference (WC), waist-to-height ratio (WtHR), CIMT (measured by SonoSite Micromax ultrasound), blood pressure (BP), fasting C-reactive protein (CRP), and cholesterol and glucose levels. Data were analysed using the Statistical Package for Social Science. One-third of the teachers were physically inactive (33%) and had low-grade inflammation CRP ≥ 3 mg/L (41%). Males were more sedentary and had higher BP and CIMT (p < 0.05). Independent of age and sex, WC or central obesity was 2.63 times more likely (p = 0.02) to contribute to atherosclerosis, especially in females (OR: 4.23, p = 0.04). PA levels were insignificantly and negatively (β −0.034; 0.888; 0.240) related to subclinical atherosclerosis. The cardiovascular disease risk profiles and limited PA status may have curbed the beneficial impact of PA on the obesity and atherosclerosis.

Exercise Intervention Changes the Perceptions and Knowledge of Non-Communicable Disease Risk Factors among Women from a Low-Resourced Setting

We employed the Health Belief Model (HBM) as a theoretical lens to explore the influence of an exercise intervention on the perceptions and knowledge of modifiable risk factors for non-communicable diseases (NCDs) among women from a low-resource setting in South Africa. We used a mixed-methods design, gathering qualitative and quantitative data at baseline (n = 95) and again after 12 weeks (n = 55) and 24 weeks (n = 44) of an exercise intervention. Qualitative data consisted of focus group discussions exploring the knowledge and perceptions of modifiable risk factors for NCDs at the three time points. We collected quantitative measurements of modifiable risk factors for NCDs (waist-to-hip ratio, body mass index, blood pressure, peripheral blood glucose, and cholesterol) as well as objective physical activity (PA) data over seven consecutive days. Surveys on coronary heart disease and PA knowledge were conducted at all three time points. Qualitative findings indicated that health exposures and cultural traditions influenced the participant’s perceptions about PA and NCDs. Waist circumference significantly decreased at 12 weeks compared to baseline MD = 4.16, p < 0.001. There was significant improvement at 12 weeks, compared to baseline, MD = 0.59, p = 0.009 for PA knowledge, and MD = 0.68, p = 0.003 for heart disease knowledge. There were reductions from baseline to 24 weeks in diastolic blood pressure (MD = 4.97, p = 0.045), waist circumference (MD = 2.85, p = 0.023) and BMI (MD = 0.82, p = 0.004). Significant heart disease knowledge improvements were found at 24 weeks compared to baseline (MD = 0.75, p < 0.001). Supervised exercise positively influenced Black African females′ health behaviours by understanding cultural perceptions of modifiable risk factors for NCDs.

Association of physical activity with blood pressure in African ancestry men

This study tested the association of objectively measured physical activity with blood pressure and hypertension in African Caribbean men, an understudied population segment known to be at high-risk for cardiovascular disease (CVD) which has low levels of high-exertion physical activity. Men (N = 310) were from the Tobago Health Study and aged 50–89 years. Systolic (SBP) and diastolic (DBP) blood pressures were measured using an automated device, and hypertension was defined as SBP ≥ 140 mmHg, DBP ≥ 90 mmHg, or current use of antihypertensive medication. Physical activity was measured using the SenseWear Pro armband (SWA) and consisted of daily time engaged in sedentary behavior (SB), light physical activity (LPA), and moderate to vigorous activity (MVPA), as well as daily step count. Multiple regression analyses using the isotemporal substitution framework were used to test for associations between activity and blood pressures. Models were adjusted in stages for SWA wear time, age, antihypertensive medication use, alcohol consumption, smoking, diabetes, CVD, family history of hypertension, salt intake, and adiposity.

Replacement of SB with LPA was associated with lower SBP adjusted for wear time (β = -0.84, p < 0.05), but attenuated after adjustment for age. Replacement of SB with LPA was associated with lower DBP (β = -0.50) and lower odds of hypertension (OR = 0.88), adjusted for wear time and age (both p < 0.05). All model associations of replacement of SB with LPA were stronger when restricted to men not taking antihypertensive medications, regardless of their hypertension status.

These results support the strategy of increasing light physical activity for blood pressure management in high-risk Afro-Caribbean men.

Blood pressure and nitric oxide synthesis capacity in physically active and inactive groups: the SABPA study

Physical activity affects the vasculature through mechanisms related to nitric oxide bioavailability, oxidative stress, and inflammation; with endothelial function at the centre of this triad. In a South African setting, with the prevalence of hypertension and physical inactivity being alarmingly high, we aimed to investigate relationships of vascular function with markers of oxidative stress, inflammation and nitric oxide synthesis capacity in physically active and inactive groups. Based on the 2010 World Health Organisation guidelines, black and white school teachers were divided into physically active (n = 84) and physically inactive (n = 132) groups. Twenty-four-hour blood pressure (24 h BP), total peripheral resistance and Windkessel compliance were measured. Markers of oxidative stress, inflammation and nitric oxide synthesis capacity were analysed. Windkessel compliance (p = 0.041) and homoarginine (p = 0.006) were higher in the physically active group. In the same group, 24 h diastolic BP associated with total glutathione (β = 0.17; p = 0.056), and 24 h BP (systolic blood pressure: β = 0.23, p = 0.006; diastolic blood pressure: β = 0.22, p = 0.019) associated with homoarginine. In the physically inactive group, 24 h BP (systolic blood pressure: β = 0.26, p < 0.001; diastolic blood pressure: β = 0.23, p = 0.007) associated with symmetric dimethylarginine (SDMA). These associations were independent of inflammation. Despite only reaching moderate physical activity levels, vascular function and nitric oxide synthesis capacity were more favourable in the physically active population compared to the physically inactive population. These results may suggest that even moderate physical activity could increase nitric oxide synthesis capacity, which in turn may mitigate the development of cardiovascular disease in this population.

Is Daily Composition of Movement Behaviors Related to Blood Pressure in Working Adults?

INTRODUCTION

To investigate the association of the daily composition of time spent sedentary, in light physical activity and moderate-to-vigorous physical activity and time in bed (movement behaviors) with blood pressure (BP) among white- and blue-collar workers.

METHODS

Systolic BP (SBP), diastolic BP (DBP) and body mass index of 827 workers were objectively measured. Daily composition of movement behaviors was derived from an Actigraph placed on the thigh for 1 to 5 d using the Acti4 software (2012-2013). The composition was expressed as isometric log-ratios. The cross-sectional associations between daily movement behavior composition and BP were investigated using the Compositional Data Analysis approach. The associations were adjusted for age, sex, body mass index, lift/carry duration, medication intake, and job sector.

RESULTS

Daily composition of time spent in movement behaviors was significantly associated with SBP (F = 2.84, P = 0.04), but not DBP (F = 0.48, P = 0.69). Specifically, time reallocation to sedentary time and light physical activity from the remaining behaviors was deleteriously associated with SBP, whereas time reallocation to time in bed and moderate-to-vigorous physical activity from the remaining behaviors was beneficially associated with SBP. However, the results were only significant for time spent sedentary (P = 0.01) and in bed (P = 0.047).

CONCLUSIONS

Daily composition of movement behaviors is associated with SBP among workers. Spending more time sedentary compared with other behaviors was deleteriously associated with SBP, whereas spending more time in bed was beneficially associated with SBP. How time is spent in different movement behaviors throughout the day is important for BP and needs to be further investigated to be included in future clinical practice guidelines.