Relationships between physical activity, cardiorespiratory fitness and sedentary behaviour, and risk factors for cardiovascular disease and type 2 diabetes, in black South African women

Includes abstract.Includes bibliographical references.Non-communicable diseases (NCDs), including cardiovascular disease (CVD) and type 2 diabetes (T2D), constitute the second highest cause of mortality in South Africa (SA) and seem to be exacerbated by the high prevalence of obesity, particularly amongst black SA women. Although the aetiology of obesity is complex, common antecedents for its development include a sedentary lifestyle and poor nutrition. The overall aim of this thesis was to examine the association between physical activity (PA) and risk factors for CVD and T2D in a sample of apparently healthy black SA women. The aims of this thesis were addressed in two separate studies with the following objectives: Study 1: i) to compare body composition and metabolic risk factors for CVD and T2D between active and inactive groups classified according to international PA recommendations for health (Part 1, crosssectional analysis) and ii) to determine whether PA level predicts changes in body composition and metabolic risk factors for CVD and T2D over a 5.5-year follow-up period (Part 2, longitudinal analysis); Study 2: to examine the independent effects of PA, cardiorespiratory fitness (CRF) and sedentary time on body composition and metabolic risk factors for CVD and T2D (cross-sectional analysis). In part 1 of study 1, a sample of 240 apparently healthy black SA women(26±7 years) underwent the following measurements in 2005/6: PA (Global PhysicalActivity Questionnaire (GPAQ)), body composition (dual-energy x-ray absorptiometry and computerised tomography), blood pressure, fasting glucose, insulin and lipid concentrations. Thereafter (part 2), a sub-sample of women (n=57) underwent follow-up testing after a 5.5-year follow period (2010/11), which included additional measurements of objective PA (accelerometry) and CRF (VO2max, ml/kg/min) measured during a submaximal step-test. Study 2 included women from the follow-up subsample and 19 additional women (n=76). Cross-sectional comparisons of objective PA, CRF and sedentary time with body composition and metabolic risk factors for CVD and T2D were examined. Study 1: Using the GPAQ, the majority (61%) of women were sufficiently active, meeting the guidelines for moderate- to vigorous-intensity physical activity (MVPA) according to international criteria. Women who were active had significantly lower body weight (p<0.001), measures of body fat (BMI, fat mass, %body fat, waist circumference, central and appendicular fat mass, p<0.001), and measures of insulin resistance (fasting serum insulin, p=0.010 and HOMA-IR, p=0.010, respectively), and higher high-density lipoprotein cholesterol (HDL-C, p=0.041) compared to the inactive group. At follow-up, bodyweight increased from 82.0±19.6 kg to 89.5±19.2 kg (p<0.001) in the active group, and from 91.0±15.6 kg to 98.3±13.2 kg (p<0.001) in the inactive group, whereas serum lipid concentrations remained unchanged (p>0.05), and diastolic blood pressure decreased significantly in those who were active (78±7 vs. 74±14 mmHg, p=0.039). Study 2: Using accelerometry as an objective measure of PA, more than half (51.3%) of the women met international MVPA criteria and the goal of ≥10 000 steps per day (55.3%). Greater light PA and steps per day, but not MVPA, were associated with lower trunk (central) fat mass (r=-0.25, p=0.03, r=-0.31, p=0.01 and r=-0.09, p=0.42, respectively). Conversely, greater sedentary time was associated with higher TG and TG/HDL-C (r=0.36, p=0.01 and r=0.34, p=0.04, respectively), and these relationships were independent of body fat. In addition, higher CRF was associated with reduced body fat% (r=-0.34, p=0.02) and central fat mass (r=-0.31, p=0.03), as well as reduced insulin resistance (HOMA-IR; r=-0.41, p=0.01). These associations were independent of body fat and PA, but not VAT. CRF was inversely associated with sedentary time (r=-0.31, p=0.03) and not with any of the PA variables (p>0.05). Both PA and CRF level were associated with reduced total and central fat mass, and reduced metabolic risk for CVD and T2D amongst a sample of apparently healthy black SA women. Promotion of increasing daily PA, including light-intensity and MVPA, whilst reducing sedentary time, and increasing CRF should be encouraged to reduce levels of obesity and risk factors for CVD and T2D

Socio-cultural, environmental and behavioural determinants of obesity in black South African women

South Africa (SA) is undergoing a rapid epidemiological transition and has the highest prevalence of obesity in sub- Saharan Africa (SSA), with black women being the most affected (obesity prevalence 31.8%). Although genetic factors are important, socio-cultural, environmental and behavioural factors, as well as the influence of socio-economic status, more likely explain the high prevalence of obesity in black SA women. This review examines these determinants in black SA women, and compares them to their white counterparts, black SA men, and where appropriate, to women from SSA. Specifically this review focuses on environmental factors influencing obesity, the influence of urbanisation, as well as the interaction with socio-cultural and socio-economic factors. In addition, the role of maternal and early life factors and cultural aspects relating to body image are discussed. This information can be used to guide public health interventions aimed at reducing obesity in black SA women.Department of HE and Training approved lis

Meeting physical activity guidelines is associated with reduced risk for cardiovascular disease in black South African women; a 5.5-year follow-up study

Background: Low levels of physical activity (PA) have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D), but few studies have examined whether meeting international PA guidelines is associated with reduced risk in a black South African (SA) population. The aims of this study were to compare body composition and cardio-metabolic risk factors for CVD and T2D between active and inactive groups (part 1, cross-sectional analysis) and, to determine whether PA level predicts changes in body composition and cardio-metabolic risk factors for CVD and T2D at follow-up after 5.5-years (part 2, longitudinal analysis). Methods: Part 1 included a sample of 240 apparently healthy black SA women (26 ± 7 years) who underwent the following measurements at baseline: PA (Global Physical Activity Questionnaire (GPAQ)), body composition and regional fat distribution (dual-energy x-ray absorptiometry and computerised tomography), blood pressure, fasting glucose, insulin and lipid concentrations. For part 2, a sub-sample of women (n = 57) underwent the same measurements after a 5.5-year period. Results: At baseline, 61% of women were classified as meeting the guidelines for moderate- to vigorous-intensity physical activity (MVPA) according to GPAQ. Women who were active had significantly lower body weight (p < 0.001), body fat (BMI, fat mass, % body fat, waist circumference, central and appendicular fat mass, all p < 0.001), and measures of insulin resistance (fasting serum insulin and HOMA-IR, both p = 0.01), and higher high-density lipoprotein cholesterol (p = 0.041), compared to the inactive group. At follow-up, all body fat measures increased significantly in both groups and diastolic blood pressure decreased significantly in those who were active at baseline, but did not change in those who were inactive. Conclusions: Meeting PA guidelines was associated with decreased risk for CVD and T2D in black SA women, but did not prevent the increase in body fat over time. Interventions promoting physical activity to specifically address obesity in this high-risk group are recommended

Behavioural lifestyle factors, physical health-related fitness and cardiometabolic disease risk in women from a low socio-economic urban community in Stellenbosch (Western Cape)

Thesis (PhD)--Stellenbosch University, 2020.ENGLISH ABSTRACT: Non-communicable diseases (NCDs), such as cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM), represent an ever-rising threat to the effective management of national health in South Africa. This especially among low versus high socio-economic urban communities as evidenced almost a decade ago. The results of which are likely to lead to an even higher demand for chronic public health care provision, and thus put immediate economic strain on the imminent South African (SA) National Health Insurance fund soon to be launched in 2026. However, one could argue that the evidence needed to reformulate the existing SA health policies, especially those directed at NCD-risk management and inclusive of modifiable behavioural/lifestyle factors, is either: i) not implemented and no action is taken; or ii) implemented, yet ineffective; or iii) limited and thus unable to detect a clinically significant effect to date. Thus, the primary aim of this study was to characterise behavioural/lifestyle factors namely physical activity (PA) and sedentary behaviour, as well as physical health-related fitness and cardiometabolic disease risk profiles for CVD and T2DM in a group of urban women from an under-resourced Western Cape community. In addition, to determine whether physical inactivity, sedentarism and poor health-related fitness levels are important predictors of obesity and other cardiometabolic disease risk outcomes associated with CVD and T2DM. Fifty-one (N=51) apparently healthy women (42 ± 13 yrs) underwent the following measurements: physical activity (PA) and sedentary time (ST), anthropometric, cardiovascular and physical-health related fitness (cardiorespiratory fitness [CRF] and muscular strength). Results from the study showed that less than a third of the women met the World Health Organisation (WHO) Global Health Recommendations for moderate to vigorous-intensity PA (MVPA) using accelerometry. Although overweight, women who accumulated ≥ 30-min of MVPA per day presented with more favourable body composition and regional body fat measures, compared to those who did not. In addition, women who were sufficiently active presented with reduced cardiometabolic disease risk. Although the associations between PA (intensities and volume) and CRF were not statistically significant, all were positive and showed clinically important associations. Independent of steps/day, higher CRF was associated with women who were younger and with reduced measures of total and central adiposity (p < 0.001). Whereas higher physical health-related fitness as opposed to ST and MVPA, was independently associated with reduced cardiometabolic risk but potentially mediated by adiposity. In an attempt to combat cardiometabolic disease risk for CVD and T2DM among low socio-economic community urban-dwelling women, public health interventions should target domains in which time is already spent physically active. Such as walking briskly for travel- and/or occupational-related activities, while also aiming to increase public awareness of the health-enhancing benefits associated with meeting MVPA recommendations. Furthermore, intervention strategies also aimed at reducing cardiometabolic risk should target physical health-related fitness while also reducing ST especially among women who are already sarcopenic. Although the success of which will only be met once we understand the community’s specific barriers to PA and healthy dietary habits.AFRIKAANSE OPSOMMING: Nie-oordraagbare siektes (NOS), soos kardiovaskulêre siektes (KVS) en tipe 2 diabetes mellitus (T2DM), verteenwoordig ’ n steeds stygende bedreiging vir die effektiewe bestuur van nasionale gesondheid in Suid-Afrika (SA). Dit is veral so in die geval van lae versus hoë sosio-ekonomiese stedelike gemeenskappe, soos wat reeds ongeveer ‘n dekade gelede bevind is. Hierdie resultate gaan heel waarskynlik aanleiding gee tot ’n selfs hoër aanvraag na die voorsiening van kroniese openbare gesondheidsorg wat onmiddellik ekonomiese druk gaan plaas op die nuut voorgestelde Suid-Afrikaanse Nasionale Gesondheidsversekering (NGV) fonds wat in 2026 in werking tree. Daar kan egter geargumenteer word dat die nodige bewyse om die bestaande Suid-Afrikaanse gesondheidsbeleide te herformuleer, veral dié gerig op NOS-risikobestuur en die inklusiwiteit van aanpasbare gedrag-/leefstylfaktore is óf: i) nie geïmplimenteer en geen aksie vind plaas nie; óf ii) geïmplimenteer, maar oneffektief; óf iii) beperk en daarom nie in staat om ’n klinies betekenisvolle effek te bespeur nie. Gevolglik was die primêre doel van die studie om die gedrag-/leefstylfaktore, naamlik fisieke aktiwiteit (FA) en sedentêre gedrag, asook fisieke gesondheidsverwante fiksheid en die risiko vir kardiometaboliese siekte profiele vir KVS en T2DM in ’n groep stedelike vrouens vanuit ’n voorheen benadeelde Wes-Kaaplandse gemeenskap, te bepaal. Daarmee saam het die studie ten doel gehad om te bepaal of fisieke onaktiwiteit, sedentêre gedrag en swak gesondheidsverwante fiksheidsvlakke belangrike voorspellers van vetsug en ander kardiometaboliese risiko’s wat met KVS en T2DM geassosieer kan word. Een-en-vyftig (N=51), klaarblyklik gesonde vrouens (42 ± 13 jr) is aan die volgende metings onderwerp: fisieke aktiwiteit (FA) en sedentêre tyd (ST); antropometrie; kardiovaskulêre en fisieke gesondheidsverwante fiksheid (kardiorespiratoriese fiksheid [KRF] en spierkrag). Die resultate, soos bepaal met draagbare versnellingsmeters, het aangedui dat minder as ’n derde van die vroue aan die Wêreld Gesondheidsorganisasie (WGO) se Globale Gesondheidsaanbevelings vir matige tot hoë intensiteit FA (MHFA) voldoen het. Alhoewel oorgewig, het die vroue wat ≥ 30-min MHFA per dag geakkumuleer het, ’n meer gunstige liggaamsamestelling en liggamsvetmates getoon in vergelyking met vroue wat nie aan die vereiste MHFA per dag voldoen het nie. Daarmee saam het vroue wat voldoende aktief was ’n verminderde risiko vir kardiometaboliese siektes getoon. Alhoewel die assosiasies tussen FA (intensiteit en volume) en KRF nie statisties betekenisvol was nie, was almal positief en het klinies belangrike assosiasies getoon. Uitsluitend die treë per dag, is hoër KRF in jonger vroue met verminderde mates van totale en sentrale adipositeit, geassosieer (p < 0.001). Alhoewel hoër fisieke gesondheidsverwante fiksheid, in teenstelling met ST en MHFA, onafhanklik met verminderde kardiometaboliese risiko geassosieer het, kon dit heel moontlik deur adipositeit bemiddel gewees het. In ’n poging om die risiko vir kardiometaboliese siekte vir KVS en T2DM onder vrouens in ʼn lae sosio-ekonomiese stedelike gemeenskap te beveg, moet openbare gesondheidsintervensies domeine teiken waarin tyd reeds spandeer word om fisiek aktief te wees - byvoorbeeld, aktiwiteite soos vinnig stap om by ’n bestemming uit te kom en/of beroepsverwante aktiwiteite. Die doel behoort ook te wees om openbare bewustheid van die gesondheidsvoordele wat gepaard gaan met die bereiking van die MHFA aanbevelings te verhoog. Verder moet intervensiestrategieë gerig op die vermindering van kardiometaboliese risiko’s veral fisieke gesondheidsverwante fiksheid teiken en terselfdertyd ST, veral onder vroue wie alreeds sarkopenies is, verminder. Sukses sal egter net bereik word wanneer gemeenskappe se spesifieke hindernisse tot deelname aan FA en gesonde dieetgewoontes verstaan word.Doctora