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Influence of Cut-Points on Patterns of Accelerometry-Measured Free-Living Physical Activity in Rural and Urban Black South African Women

Ian Cook, Marianne Alberts, and Estelle V. Lambert

Background:

We describe the effect of 2 different accelerometer cut-points on physical activity (PA) patterns in rural and urban black South African women.

Methods:

Hip-mounted uni-axial accelerometers were worn for 6 to 7 days by rural (n = 272) and urban (n = 16) participants. Twenty-hour (4 AM to 12 AM) PA counts (cts) and volumes (min·day−1) were extracted: sedentary (SED, <100 cts·min−1), light (100–759 cts·min−1), moderate-1 (MOD1, 760–1951 cts·min−1), moderate-2 to vigorous (MOD2VG, ≥1952 cts·min−1), and bouts ≥10 min for ≥760 cts·min−1 (MOD1VGbt) and ≥1952 cts·min−1 (MOD2VGbt).

Results:

Valid data were obtained from 263 rural women and 16 urban women. Total counts and average counts were higher (+80,399 cts·day−1, +98 cts·min−1.day−1) (P < .01), SED lower (−61 min·day−1, P = .0042), MOD1 higher (+65 min·day−1, P < .0001), and MOD1VGbt higher (+19 min·day−1, P = .0179) in rural women compared with urban women. Estimated adherence (≥30 min·day−1 for 5 days·wk−1) was 1.4-fold higher in rural women than urban women for MOD-1VGbt, but 3.3-fold higher in urban women than rural women for MOD2VGbt.

Conclusions:

Rural women accumulate greater amounts of PA than urban women within a particular count band. Depending on which moderate PA cut-point was used to estimate PA public health adherence, rural women could be classified as less physically active than urban women.

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A Retrospective Evaluation of a Community-Based Physical Activity Health Promotion Program

Catherine E. Draper, Tracy L. Kolbe-Alexander, and Estelle V. Lambert

Background:

The Community Health Intervention Programmes (CHIPs) is a physical activity-based health promotion program operating in disadvantaged communities in the Western Cape, South Africa with primary school learners, adults and senior adults. Program growth, anecdotal evidence and experience of those involved suggest the program has been positively received by communities. The aim of this study was to conduct a qualitative, retrospective process evaluation concerning both factors associated with successful implementation of the programs, and implementation challenges.

Methods:

‘Success’ was defined in consultation with CHIPs staff and stakeholders. Data were gathered through naturalistic observation, structured interviews and focus groups (n = 104), and open-ended questionnaires (n = 81). The sample included CHIPs staff and stakeholders, program members and leaders.

Results:

Factors contributing to the program’s success include: focus on combining social development and exercise science, community development model, scientifically sound program content, appropriate activities, intrapersonal and interpersonal factors, program leadership, encouraging staff, and various contextual factors.

Conclusions:

The findings confirm that CHIPs presents a model of sustainable implementation of physical activity in disadvantaged communities, and that it positively impacts the quality of life, perceptions of the role of physical activity in health, and personal responsibility for health of those involved in its programs.

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Free Living Energy Expenditure in Post Menopausal Women before and after Exercise Training

Lara R. Keytel, Michael I. Lambert, Judith Johnson, Timothy D. Noakes, and Estelle V. Lambert

The aim of the study was to determine the effects of 8 weeks of moderate exercise training, on 24-hour free living energy expenditure in previously sedentary post-menopausal women. The experimental group (EX) included 9 women. Ten non-exercising control subjects (CON) were recruited to undergo pre- and post-testing. Estimated total daily energy expenditure (TDEE), total 24-hour heart beats (HB), total energy intake (TEI), resting metabolic rate, maximal oxygen consumption (V̇O2max), body composition, and submaximal heart rate were measured before and after the exercise intervention. Body composition did not change (body fat % in CON 34.0 ± 4.0% vs. 33.9 ± 3.6% and EX 34.1 ± 4.0% vs. 34.0 ± 3.4%). Mean submaximal heart rate during steady-state exercise in EX was lower after training compared to CON (p < .05); however, V̇O2max did not significantly (CON 1.96 ± 0.23 vs. 1.99 ± 0.241 LO2/min and EX 1.86 ± 0.39 vs. 1.94 ± 0.30 LO2/min). Neither estimated TDEE (CON, 11.6 ± 2.0 vs. 11.4 ± 2.78 MJ; and EX 11.4 ± 3.3 vs. 11.5 ± 2.5 MJ, pre vs. post, respectively), RMR (CON 134.2 ± 9.4 vs. 136.9 ± 15.0 KJ/kgFFM/day, and EX 138.4 ± 6.4 vs. 140.7 ± 14.2 KJ/kgFFM/day, pre vs. post, respectively), TEI (CON 7.9 ± 2.2 vs. 8.2 ± 2.5 MJ, and EX 9.4 ±1.6 vs. 8.3 ± 2.8 MJ), nor HB (CON 110,808 ± 12,574 vs. 107,366 ± 12,864 beats, and EX 110,188 ± 9,219 vs. 114,590 ± 12,750 beats) change over 8 weeks in either group. These data suggest that a moderate exercise program may not impact on TDEE, RMR, TEI, or HB in previously sedentary, older women.

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The Effects of Medium-Chain Triacylglycerol and Carbohydrate Ingestion on Ultra-Endurance Exercise Performance

Julia H. Goedecke, Virginia R. Clark, Timothy D. Noakes, and Estelle V. Lambert

The aims of the study were to determine if medium-chain triacylglycerol (MCT), ingested in combination with carbohydrate (CHO), would alter substrate metabolism and improve simulated competitive ultra-endurance cycling performance. Eight endurance-trained cyclists took part in this randomized, single-blind crossover study. On two separate occasions, subjects cycled for 270 min at 50% of peak power output, interspersed with four 75 kJ sprints at 60 min intervals, followed immediately by a 200 kJ time-trial. One hour prior to the exercise trials, subjects ingested either 75 g of CHO or 32 g of MCT, and then ingested 200 mL of a 10% CHO (wt/vol) solution or a 4.3% MCT + 10% CHO (wt/vol) solution every 20 min during the CHO and MCT trials, respectively. During the constant-load phases of the 270 min exercise trial, VO2, RER, and heart rate were measured at 30 min intervals and gastrointestinal (GI) symptoms were recorded. There was no difference in VO2 or RER between the MCT and CHO trials (P = 0.40). Hourly sprint (P = 0.03 for trial x time interaction) and time-trial times (14:30 ± 0.58 vs. 12:36 ± 1:6, respectively, P < 0.001) were slower in the MCT than the CHO trial. Half the subjects experienced GI symptoms with MCT ingestion. In conclusion, MCTs ingested prior to exercise and co-ingested with CHO during exercise did not alter substrate metabolism and significantly compromised sprint performance during prolonged ultra-endurance cycling exercise.

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Decreased Resting Metabolic Rate in Ballet Dancers with Menstrual Irregularity

Kathryn H. Myburgh, Claire Berman, Illana Novick, Timothy D. Noakes, and Estelle V. Lambert

We studied 21 ballet dancers aged 19.4 ± 1.4 years, hypothesizing that undernu-trition was a major factor in menstrual irregularity in this population. Menstrual history was determined by questionnaire. Eight dancers had always been regular (R). Thirteen subjects had a history of menstrual irregularity (HI). Of these, 2 were currently regularly menstruating, 3 had short cycles, 6 were oligomenorrheic, and 2 were amenorrheic. Subjects completed a weighed dietary record and an Eating Attitudes Test (EAT). The following physiological parameters were measured: body composition by anthropometry, resting metabolic rate (RMR) by open-circuit indirect calorimetry, and serum thyroid hormone concentrations by radioimmunoassay. R subjects had significantly higher RMR than HI subjects. Also, HI subjects had lower RMR than predicted by fat-free mass, compared to the R subjects. Neitherreported energy intake nor serum thyroid hormone concentrations were different between R and HI subjects. EAT scores varied and were not different between groups. We concluded that in ballet dancers, low RMR is more strongly associated with menstrual irregularity than is currentreported energy intake or serum thyroid hormone concentrations.

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Comparison of Two Methods of Measuring Physical Activity in South African Older Adults

Tracy L. Kolbe-Alexander, Estelle V. Lambert, Judith Biletnikoff Harkins, and Ulf Ekelund

The aim of this study was to assess the validity and reliability of the Yale Physical Activity Survey (YPAS) and the short version of the International Physical Activity Questionnaire (IPAQ) in older South African adults. The YPAS includes measures of weekly energy expenditure (EE) for housework, yard work, caregiving, exercise, and recreation. The IPAQ measures total time and EE during vigorous and moderate activity, walking, and sitting. The instruments were administered twice for test–retest reliability (men, n = 52, 68 ± 5.4 years, and women, n = 70, 66 ± 5.8 years). Data for criterion validity were obtained from accelerometers. YPAS reliability ranged from r = .44 to.80 for men and r = .59 to .99 for women (p < .0001). IPAQ reliability was lower for men (r = .29 to .76) than for women (r = .46 to .77). Criterion validity of the YPAS was .31 to .54 for men and .26 to .29 for women. The YPAS and short IPAQ had comparable results for reliability and criterion validity.

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Does Physical Activity Mediate the Association Between Perceived Neighborhood Aesthetics and Overweight/Obesity Among South African Adults Living in Selected Urban and Rural Communities?

Pasmore Malambo, Andre P. Kengne, Estelle V. Lambert, Anniza De Villiers, and Thandi Puoane

Background: To investigate the mediation effects of physical activity (PA) on the relationship between the perceived neighborhood aesthetic environment and overweight/obesity in free-living South Africans. Methods: A cross-sectional study of 671 adults aged ≥ 35 years was analyzed. PA was assessed using the validated International Physical Activity Questionnaire. Perceived neighborhood aesthetics was assessed using the Neighborhood Environment Walkability Scale Questionnaire. Results: Of 671 participants, 76.0% were women, 34.1% aged 45–54 years, and 69.2% were overweight or obese. In adjusted logistic regression models, overweight/obesity was significantly associated with neighborhood aesthetics [odds ratio (OR) = 0.68; 95% confidence interval (CI), 0.50–0.93] and PA (OR = 0.65; 95% CI, 0.65–0.90). In expanded multivariable models, overweight/obesity was associated with age 45–55 years (OR = 1.59; 95% CI, 1.05–2.40), female gender (OR = 6.24; 95% CI, 3.95–9.86), tertiary education (OR = 4.05; 95% CI, 1.19–13.86), and urban residence (OR = 2.46; 95% CI, 1.66–3.65). Conclusion: Aesthetics was positively associated with PA; both aesthetics and PA were negatively associated with overweight and obesity. There was no evidence to support a significant mediating effect of PA on the relationship between aesthetics and overweight/obesity. Future studies should consider objective assessment of aesthetics and PA. In addition, future studies should consider using longitudinal design to evaluate food-related environments, which are related to overweight or obesity.

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Results from South Africa’s 2014 Report Card on Physical Activity for Children and Youth

Catherine Draper, Susan Basset, Anniza de Villiers, Estelle V. Lambert, and the HAKSA Writing Group

Background:

There is current concern for the health and well-being of children and youth in South Africa, including habits of physical activity (PA) and sedentary behavior. The 2014 Healthy Active Kids South Africa Report Card evaluates the current activity status of children and youth.

Methods:

The Research Working Group was comprised of 23 experts in physical education, nutrition, sport science, public health and journalism. The search was based on a systematic review of peer-reviewed literature (previous 5 years), dissertations, and nonpeer-reviewed reports (‘gray’ literature) dealing with the PA and nutritional status of South African children and youth 6−18 years of age. Key indicators were identified and data extracted. Grades for each indicator were discussed and assigned.

Results:

Overall PA levels received a D grade, as roughly 50% or more of children and youth were not meeting recommended levels. Organized sports participation fared better with a C, and government policies were promising, receiving a B. Screen time and sedentary behavior were a major concern and received a grade of F. Under- and over-weight were highlighted, but overweight is on the rise and this indicator was assigned a D grade. Most of the other indicators in South Africa remained the same or became worse so that grades declined from C- to D. In particular, sedentary behavior, soft-drink and fast food consumption, and an ineffectual regulatory environment to control advertising to children were a concern. There is need to engage parents and communities for advocacy and social mobilization.

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Variability in Exercise Capacity and Metabolic Response During Endurance Exercise After a Low Carbohydrate Diet

Amanda Claassen, Estelle V. Lambert, Andrew N. Bosch, Ian M. Rodger, Alan St. Clair Gibson, and Timothy D. Noakes

The impact of altered blood glucose concentrations on exercise metabolism and performance after a low carbohydrate (CHO) diet was investigated. In random order, 1 wk apart, 9 trained men underwent euglycemic (CI) or placebo (PI) clamps, while performing up to 150 min of cycling at 70% VO2max, after 48 h on a low CHO diet. The range in improvement in endurance capacity with glucose infusion was large (28 ± 26%, P < 0.05). Fifty-six percent of subjects in CI failed to complete 150 min of exercise despite maintenance of euglycemia, while only 2 subjects in PI completed 150 min of exercise, despite being hypoglycemic. Total CHO oxidation remained similar between trials. Despite longer exercise times in CI, similar amounts of muscle glycogen were used to PI. Maintenance of euglycemia in the CHO-depleted state might have an ergogenic effect, however, the effect is highly variable between individuals and independent of changes in CHO oxidation.

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High-Fat Diet versus Habitual Diet Prior to Carbohydrate Loading: Effects on Exercise Metabolism and Cycling Performance

Estelle V. Lambert, Julia H. Goedecke, Charl van Zyl, Kim Murphy, John A. Hawley, Steven C. Dennis, and Timothy D. Noakes

We examined the effects of a high-fat diet (HFD-CHO) versus a habitual diet, prior to carbohydrate (CHO)-loading on fuel metabolism and cycling time-trial (TT) performance. Five endurance-trained cyclists participated in two 14-day randomized cross-over trials during which subjects consumed either a HFD (>65% MJ from fat) or their habitual diet (CTL) (30 ± 5% MJ from fat) for 10 day, before ingesting a high-CHO diet (CHO-loading, CHO > 70% MJ) for 3 days. Trials consisted of a 150-min cycle at 70% of peak oxygen uptake (V̇O2peak), followed immediately by a 20-km TT. One hour before each trial, cyclists ingested 400 ml of a 3.44% medium-chain triacylglycerol (MCT) solution, and during the trial, ingested 600 ml/hour of a 10% 14C-glucose + 3.44% MCT solution. The dietary treatments did not alter the subjects’ weight, body fat, or lipid profile. There were also no changes in circulating glucose, lactate, free fatty acid (FFA), and β-hydroxybutyrate concentrations during exercise. However, mean serum glycerol concentrations were significantly higher (p < .01) in the HFD-CHO trial. The HFD-CHO diet increased total fat oxidation and reduced total CHO oxidation but did not alter plasma glucose oxidation during exercise. By contrast, the estimated rates of muscle glycogen and lactate oxidation were lower after the HFD-CHO diet. The HFD-CHO treatment was also associated with improved TT times (29.5 ± 2.9 min vs. 30.9 ± 3.4 min for HFD-CHO and CTL-CHO, p < .05). High-fat feeding for 10 days prior to CHO-loading was associated with an increased reliance on fat, a decreased reliance on muscle glycogen, and improved time trial performance after prolonged exercise.