Sarah J. Moss

Are behavioural risk factors to be blamed for the conversion from optimal blood pressure to hypertensive status in Black South Africans? A 5-year prospective study

BACKGROUND Longitudinal cohort studies in sub-Saharan Africa are urgently needed to understand cardiovascular disease development. We, therefore, explored health behaviours and conventional risk factors of African individuals with optimal blood pressure (BP) (≤ 120/80 mm Hg), and their 5-year prediction for the development of hypertension. METHODS The Prospective Urban Rural Epidemiology study in the North West Province, South Africa, started in 2005 and included African volunteers (n = 1994; aged > 30 years) from a sample of 6000 randomly selected households in rural and urban areas. RESULTS At baseline, 48% of the participants were hypertensive (≥ 140/90 mmHg). Those with optimal BP (n = 478) were followed at a success rate of 70% for 5 years (213 normotensive, 68 hypertensive, 57 deceased). Africans that became hypertensive smoked more than the normotensive individuals (68.2% vs 49.8%), and they also had a greater waist circumference [ratio of geometric means of 0.94 cm (95% CI: 0.86-0.99)] and greater amount of γ-glutamyltransferase [0.74 U/l (95% CI: 0.62-0.88)] at baseline. The 5-year change in BP was independently explained by baseline γ-glutamyltransferase [R(2) = 0.23, β = 0.13 U/l (95% CI: 0.01-0.19)]. Alcohol intake also predicted central systolic BP and carotid cross-sectional wall area (CSWA) at follow-up. Waist circumference was another predictor of BP changes [β = 0.18 cm (95% CI: 0.05-0.24)] and CSWA. HIV infection was inversely associated with increased BP. CONCLUSIONS During the 5 years, 24% of Africans with optimal BP developed hypertension. The surge in hypertension in Africa is largely explained by modifiable risk factors. Public health strategies should focus aggressively on lifestyle to prevent a catastrophic burden on the national health system.

The relationship between body composition and physical fitness in 14 year old adolescents residing within the Tlokwe local municipality, South Africa: The PAHL study

BackgroundLittle is known about the relationship between body composition and physical fitness in 14 year-old high school adolescents of South Africa. Baseline data from a longitudinal study on physical activity and health (PAHLS) may provide valuable information for future studies, hence to inform public health policy makers. The objectives of this study are to determine the prevalence of underweight, normal weight and overweight among adolescents aged 14 years in the Tlokwe Local Municipality of the North West Province of South Africa, and to assess the association between physical fitness and body composition separately for boys and girls, adjusted for race and locality.MethodsBody weight, height and triceps, and subscapular skinfolds of 256 adolescents (100 boys and 156 girls) aged 14 years were measured, and percentage body fat and body mass index (BMI) were calculated. BMI was used to determine underweight, normal weight and overweight based on the standard criterion. Physical fitness was assessed by standing broad jump, bent arm hang and sit-ups according to the EUROFIT fitness standard procedures. Multinomial logistic regression analyses stratified for gender and adjusted for race (black or white), and the locality (urban or township) of the schools were used to analyze the data.ResultsIn the total group 35.9% were underweight and 13.7% overweight. Boys were more underweight (44%) than girls (30.7%). The prevalence of overweight was 8% in boys and 17.3% in girls. BMI was strongly (p = 0.01) related with percentage body fat. Strong and significant positive associations between physical fitness and BMI for the underweight girls with high physical fitness scores (OR, 10.69 [95%CI: 2.81-40.73], and overweight girls with high physical fitness scores (OR, 0.11 [95%CI: 0.03-0.50]) were found. Non-significant weaker positive relationship between physical fitness and BMI for the underweight boys with high physical fitness scores (OR, 1.80 [95%CI: 0.63-5.09]), and the overweight boys with high physical fitness scores (OR, 0.18 [95%CI: 0.02-1.78]) were found.ConclusionBoth underweight and overweight among boys and girls in Tlokwe Local Municipality exist, and their effects on physical fitness performances were also noticed. As such, strategic physical activity, interventions or follow-up studies recognizing this relationship particularly in the overweight adolescents are needed. In addition, authorities in health and education departments dealing with adolescents should make use of this evidence base information in policies development.

Changes in coronary heart disease risk profile of adults with intellectual disabilities following a physical activity intervention

BACKGROUND Regular physical activity is one of the modifiable risk factors for coronary heart disease (CHD). With an increasing age profile and similar patterns of morbidity to the general population, persons with intellectual disabilities (ID) and their caregivers would benefit from data that indicate CHD risk factors. Knowledge of the CHD risk factors and the changes a physical activity intervention may have on theses risk factors will facilitate future intervention programmes. METHODS A cohort of 100 men and women between the ages of 21 and 73 years with ID living in a community group home in the North-West Province of South Africa was recruited. A CHD risk profile was compiled by means of a questionnaire and physical assessment that included resting blood pressure, body mass index, non-fasting glucose and cholesterol and cardiorespiratory fitness. A 12-week physical activity intervention was then conducted 3 days/week after which the baseline measurements were repeated. RESULTS The results indicated that 85% of the participants were inactive, while 67% were overweight and obese. Hypertension (6.1%) and smoking (6.1%) were relatively low in this population with ID. Glucose concentrations above the recommended cut-off values were observed in 28% of the participants. Total cholesterol concentrations above normal were measured in 23% of the participants. The physical activity intervention reduced inactivity to 50% and resulted in a significant increase in cardiorespiratory fitness and a decrease in percentage body fat in both men and women. CONCLUSION Inactivity is a major risk factor in this population with ID living in a community group setting. The implementation of the physical activity intervention significantly reduced the risk factors for CHD.

Reference ranges of handgrip strength from 125,462 healthy adults in 21 countries: a prospective urban rural epidemiologic (PURE) study

The measurement of handgrip strength (HGS) has prognostic value with respect to all‐cause mortality, cardiovascular mortality and cardiovascular disease, and is an important part of the evaluation of frailty. Published reference ranges for HGS are mostly derived from Caucasian populations in high‐income countries. There is a paucity of information on normative HGS values in non‐Caucasian populations from low‐ or middle‐income countries. The objective of this study was to develop reference HGS ranges for healthy adults from a broad range of ethnicities and socioeconomically diverse geographic regions.

The relationship between body composition and selected metabolic syndrome markers in black adolescents in South Africa: The PLAY study

OBJECTIVE To determine the relationship between body composition and selected markers of the metabolic syndrome in black adolescents. METHODS The group consisted of 232 adolescent boys and girls aged 15-19 y attending two secondary schools in a low socio-economic status area of Potchefstroom, South Africa. Body mass (kg), stature (cm), and waist (WC) and hip circumferences were measured using standard methods. Body mass index and waist:hip ratio were calculated. Percentage body fat and lean body mass were measured by air displacement plethysmography. Fasting plasma insulin, fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), systolic blood pressure (SBP), and diastolic blood pressure were measured. RESULTS Children with a high body fat percentage (boys >20%, girls >25%) had significantly higher serum leptin concentration than children with normal body fat percentage (boys, P = 0.005; girls, P < 0.0001). Girls with a high body fat percentage also reported significantly higher SBP (P = 0.004), diastolic blood pressure (P = 0.03), plasma insulin (P = 0.004), and HOMA-IR (P = 0.004) than girls with normal body fat percentage. Body fat percentage had a significant positive association with HOMA-IR (P = 0.02) and SBP (P = 0.02), respectively. A significant positive correlation was also found between plasma leptin concentration and body mass index (P < 0.0001), WC (P < 0.0001), body fat percentage (P < 0.0001), and fat:height index (P < 0.001). CONCLUSION A significant positive association was found between body fat percentage and both SBP and HOMA-IR, respectively. Girls with a high body fat percentage had significantly higher BP, plasma insulin, and HOMA-IR than girls with normal body fat percentage, indicating risk of non-communicable diseases.

Gene–environment and gene–gene interactions of specific MTHFR, MTR and CBS gene variants in relation to homocysteine in black South Africans

The methylenetetrahydrofolate reductase (MTHFR), cystathione-β-synthase (CBS) and methionine synthase (MTR) genes interact with each other and the environment. These interactions could influence homocysteine (Hcy) and diseases contingent thereon. We determined single nucleotide polymorphisms (SNPs) within these genes, their relationships and interactions with total Hcy concentrations within black South Africans to address the increased prevalence of diseases associated with Hcy. The MTHFR 677 TT and MTR 2756 AA genotypes were associated with higher Hcy concentrations (16.6 and 10.1 μmol/L; p<0.05) compared to subjects harboring the MTHFR 677 CT/CC and the MTR 2756 AG genotypes (10.5, 9.7 and 9.5 μmol/L, respectively). The investigated CBS genotypes did not influence Hcy. We demonstrated interactions between the area of residence and the CBS T833C/844ins68 genotypes (p=0.005) so that when harboring the wildtype allele, rural subjects had significantly higher Hcy than their urban counterparts, but when hosting the variant allele the environment made no difference to Hcy. Between the CBS T833C/844ins68 or G9276A and MTHFR C677T genotypes, there were two-way interactions (p=0.003 and=0.004, respectively), with regard to Hcy. Subjects harboring the MTHFR 677 TT genotype in combination with the CBS 833 TT/homozygous 844 non-insert or the MTHFR 677 TT genotype in combination with the CBS 9276 GA/GG displayed higher Hcy concentrations. Therefore, some of the investigated genotypes affected Hcy; residential area changed the way in which the CBS T833C/844ins68 SNPs influenced Hcy concentrations highlighting the importance of environmental factors; and gene-gene interactions allude to epistatic effects.

Validity of the 16-metre PACER and six-minute walk test in adults with Down syndrome

Abstract Purpose: The purpose was to establish criterion-related validity of the 16-metre PACER and six-minute walk distance (6MWD) tests to VO2 peak as well as predictors of VO2 peak in adults with Down syndrome (DS). Methods: Adults with DS (24 males and 19 females) aged 18–50 years performed the three aerobic tests on non-consecutive days during a one-week period. To assess validity, peak oxygen uptake was measured directly on a motorized treadmill. Pearson–product moment correlations were performed. Predictors of VO2 peak were assessed with a stepwise multiple regression analysis. Agreement between PACER and VO2 peak was assessed by Bland–Altman plot. Results: Linear regression revealed that the PACER (R2 = 0.86) and the 6MWD (R2 = 0.75) were significantly related to VO2 peak (p < 0.05). Both the 16-metre PACER and the 6MWD significantly correlated with VO2 peak for adults with DS. The relationship was stronger for the 16-metre shuttle run test (r = 0.87) than the 6MWD (r = 0.78). The correlation between VO2 peak and both field tests, controlling for age, gender and BMI, remained significant (r > 0.7; p < 0.05). PACER, 6MWD and BMI are significant predictors of VO2 peak (p < 0.05). Conclusion: The 16-metre PACER and 6MWD are valid field tests for predicting aerobic capacity in adults with DS. Implications for Rehabilitation The 16-metre PACER and 6MWD tests are safe and feasible for use in adults with DS. Both tests are valid indicators of cardio-respiratory fitness as assessed by moderate-to-strong coefficients of determination and correlation coefficients. Both field tests along with BMI are predictors of aerobic capacity.

Objectively determined habitual physical activity in South African adolescents: the PAHL study

BackgroundThere is limited data on objectively determined habitual physical activity (PA) in 16-year old South African adolescents. The purpose of this study was to objectively determine the habitual PA of adolescents from the North West Province of South Africa by race and gender.MethodsAdolescents (137 girls, 89 boys) from the ongoing Physical Activity and Health Longitudinal Study (PAHL study), participated in the present study. Habitual PA was objectively recorded by means of the Actiheart® over a period of 7 days. Time spent in moderate-to-vigorous intensity physical activity (MVPA) was assessed.ResultsAverage MVPA for the study sample was 50.9 ± 40.3 minutes/day. Girls were significantly more active than boys expending more time in MVPA (61.13 ± 52.2 minutes/day; p < 0.05) than boys (35.0 ± 32.9 minutes/day). Although white adolescents spent more time in MVPA than black adolescents, there was no significant difference in MVPA between black (47.87 ± 39.6 minutes/day; p = 0.58) and white adolescents (59.5 ± 41.8 minutes/day).ConclusionPhysical activity varies by both gender and race in adolescents from the North West Province of South Africa. Objectively determined data from our study indicates that girls habitually spend more time in MVPA per day than boys, and that white adolescents habitually engage in more MVPA than black adolescents. Seeing as the average MVPA per day for the entire study sample falls below the recommended daily average of 60minutes/day, adolescents should be the foremost targets of interventions aimed at enhancing habitual PA.

Thoracic posture, shoulder muscle activation patterns and isokinetic strength of semi-professional rugby union players

Background . Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours. Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professional rugby union players. Methods . Using the hand-behind-the-neck and -back methods, we manually tested the range of motion (ROM) of the shoulder joints of 91 uninjured semi-professional rugby union players who consented to participate in the study. Profiling and classification of thoracic posture was performed according to the New York Posture Test. Activation patterns of the upper and lower trapezius, serratus anterior and infraspinatus scapular muscles were determined by electromyography. The isokinetic muscle strength of the rotator cuff muscles was determined at 60°/sec by measuring the concentric and eccentric forces during internal rotation (IR) and external rotation (ER). Results . Participants presented with non-ideal or unsatisfactory internal (59%) and external (85%) rotators of the shoulder. A slightly abnormal or abnormal forward head posture was observed in 55% of participants, while 68% had an abnormal shoulder position in the lateral view. The muscle activation sequence of the rotator cuff muscles was: (i) serratus anterior, (ii) lower trapezius, (iii) infraspinatus, and (iv) upper trapezius. The isokinetic ER/IR muscle-strength ratio during concentric muscle contraction was 64% (standard deviation (SD) ±14) for the left shoulder and 54% (SD ±10) for the right shoulder. The ER/IR ratio for eccentric muscle contraction was 67% (SD ±12) and 61% (SD ±9) for the left and right shoulders, respectively. Conclusions . Non-ideal or unsatisfactory flexibility of the external rotators of the shoulder, a forward shoulder posture in the lateral view, and weakness of the external rotators did not result in an abnormal rotator cuff muscle activation pattern in this study. Postural deviations may, however, increase the risk of shoulder injury in rugby union players in the long term, and should be corrected.

Level of agreement between physical activity levels measured by ActiHeart and the International Physical Activity Questionnaire in persons with intellectual disability

Abstract Purpose: The purpose of this study was to determine the level of agreement between objective physical activity (PA) (ActiHeart®) and subjective proxy-respondent International Physical Activity Questionnaire-short version (IPAQ-S) data in adults with intellectual disabilities (IDs). Method: Fifty-eight participants wore ActiHeart® monitors for seven consecutive days. Caregivers of each participant completed the IPAQ-S on behalf of the participant. Total PA, time spent in light, moderate, and vigorous activity as well as time spent being sedentary were assessed by the IPAQ-S and the ActiHeart®. Results were compared by means of correlation analyses. The level of agreement was presented with Bland–Altman plots. Results: Objective PA (ActiHeart®) was higher (225.57 ± 91.96 min/week) than IPAQ-S PA reported by care-givers (177.06 ± 309.17 min/week). Weak significant correlations were observed between the ActiHeart® and IPAQ-S instruments for sedentary behavior (r = 0.31; p = 0.04); no significant correlations for light (r= −0.04; p = 0.8), moderate (r= −0.07; p = 0.63), or vigorous PA (r= −0.2; p = 0.18) were found. Limited agreement between objectively determine PA (ActiHeart®) and IPAQ-S was found. Conclusion: IPAQ-S is inaccurate when determining PA in persons with ID as it significantly underestimates the true levels of PA in this cohort. Implications for Rehabilitation Persons with intellectual disability (ID) report insufficient physical activity for health benefits. Physical activity is often determined by means of subjective proxy reporting. Objective physical activity measurements by means of combined heart rate and accelerometer are necessary to determine accurate levels of physical activity in persons with ID. Exercise interventions should be based on objective physical activity measurements.