A qualitative study of the perceived benefits of participating in a spinal cord rehabilitation intervention in a low-middle income country.

PURPOSE: Improving quality of life (QoL) is a major goal of rehabilitation following spinal cord injury (SCI). However, people with disabilities in resource constrained contexts have limited access to rehabilitation and poorer health outcomes, including QoL. There is a paucity of qualitative research on the experiences of persons with SCI involved in rehabilitation programmes in low-middle income countries. This study aimed to assess participants' perceptions of the benefits of a 24-week SCI rehabilitation programme delivered as part of a pilot randomized controlled trial (RCT) in South Africa. MATERIALS AND METHODS: Sixteen participants, with chronic motor-incomplete tetraplegia, were enrolled in a two-arm pilot RCT involving robotic locomotor training, a novel technology, and standard activity-based training (Pan African Clinical Trial Registry (PACTR201608001647143)). Data were collected via in-depth interviews and analysed using thematic analysis. RESULTS: Participants described several improvements in QoL, including enhanced functional independence; reduced secondary complications; and improved psychosocial and emotional well-being. CONCLUSIONS: The holistic approach to rehabilitation calls for the involvement of individuals' views about what matters to them to inform clinical practice and to highlight the role that physical activity and the perceived successes play in shaping the lived experiences after SCI. TRIAL REGISTRATION: Pan African Clinical Trial Registry (PACTR201608001647143), registration date (21st May 2016), study start date (30th Nov 2016)https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=1647.

Rehabilitation plays an integral role in prompting and integrating positive experiences and changes in QoL for people with spinal cord injury (SCI), especially in a resource constrained context where there is limited opportunity to participate in rehabilitation interventions.Locomotor training and activity-based training can enhance perceived functional independence and psychosocial well-being following SCI.Rather than focus on traditional physiological outcomes, rehabilitation interventions can address quality of life outcomes in order to improve well-being in a way that is meaningful to people with SCI.

Robotic locomotor training in a low-resource setting: a randomized pilot and feasibility trial.

PURPOSE: Activity-based Training (ABT) represents the current standard of neurological rehabilitation. Robotic Locomotor Training (RLT), an innovative technique, aims to enhance rehabilitation outcomes. This study aimed to conduct a randomized pilot and feasibility trial of a locomotor training program within South Africa. MATERIALS AND METHODS: Individuals with chronic traumatic motor incomplete tetraplegia (n = 16). Each intervention involved 60-minute sessions, 3x per week, for 24-weeks. Outcomes included feasibility measures and functional capacity. RESULTS: 17 out of 110 individuals initiated the program (recruitment rate = 15.4%) and 16 completed the program (drop-out rate = 5.8%) and attended sessions (attendance rate = 93.9%). Both groups showed a significant increase in upper extremity motor score (MS) and abdominal strength post intervention. Only the RLT group showed a significant change in lower extremity MS, with a mean increase of 3.00 [0.00; 16.5] points over time. Distance walked in the Functional Ambulatory Inventory (SCI-FAI) increased significantly (p = 0.02) over time only for the RLT group. CONCLUSIONS: Feasibility rates of the intervention and functional outcomes justify a subsequent powered RCT comparing RLT to ABT as an effective rehabilitation tool for potentially improving functional strength and walking capacity in people with incomplete SCI.

Spinal cord injury causes severe limitations to functional capacity, independence, and quality of life.Robotic Locomotor Training is growing rehabilitation modality for people with spinal cord injury, but currently its effects on functional capacity are limited.In a relatively small sample, this study shows that large, randomized control trials are feasible within a low-income setting.The preliminary findings of this study show that 12 weeks of locomotor training can improve ambulatory function and functional strength in individuals with spinal cord injury.

Robotic locomotor training for spasticity, pain, and quality of life in individuals with chronic SCI: A pilot randomized controlled trial.

Objective: The prevention and treatment of secondary complications is a key priority for people with spinal cord injury and a fundamental goal of rehabilitation. Activity-based Training (ABT) and Robotic Locomotor Training (RLT) demonstrate promising results for reducing secondary complications associated with SCI. However, there is a need for increased evidence through randomized controlled trials. Therefore, we aimed to investigate the effect of RLT and ABT interventions on pain, spasticity, and quality of life in individuals with spinal cord injuries. Methods: Participants with chronic motor incomplete tetraplegia (n = 16) were recruited. Each intervention involved 60-minute sessions, 3× per week, over 24-weeks. RLT involved walking in an Ekso GT exoskeleton. ABT involved a combination of resistance, cardiovascular and weight-bearing exercise. Outcomes of interest included the Modified Ashworth Scale, the International SCI Pain Basic Data Set Version 2, and the International SCI Quality of Life Basic Data Set. Results: Neither intervention altered symptoms of spasticity. Pain intensity increased from pre-post intervention for both groups, with a mean increase of 1.55 [-0.82, 3.92] (p = 0.03) and 1.56 [-0.43, 3.55] (p = 0.02) points for the RLT and ABT group, respectively. The ABT group had an increase in pain interference scores of 100%, 50%, and 109% for the daily activity, mood, and sleep domain, respectively. The RLT group had an increase in pain interference scores of 86% and 69% for the daily activity and mood domain respectively, but no change in the sleep domain. The RLT group had increased perceptions of quality of life with changes of 2.37 [0.32, 4.41], 2.00 [0.43, 3.56] and 0.25 [-1.63, 2.13] points, p = 0.03, for the general, physical, and psychological domains, respectively. The ABT group had increased perceptions of general, physical and psychological quality of life with changes of 0.75 [-1.38, 2.88], 0.62 [-1.83, 3.07] and 0.63 [-1.87, 3.13] points, respectively. Conclusions: Despite increased pain ratings and no change in symptoms of spasticity, there was an increase in perceived quality of life for both groups over 24-weeks. This dichotomy warrants additional investigation in future large-scale randomized controlled trials.

Association of Perceived Neighbourhood Walkability with Self-Reported Physical Activity and Body Mass Index in South African Adolescents.

Adolescence is a life stage critical to the establishment of healthy behaviours, including physical activity (PA). Factors associated with the built environment have been shown to impact PA across the life course. We examined the sociodemographic differences in, and associations between, perceived neighbourhood walkability, PA, and body mass index (BMI) in South African adolescents. We recruited a convenience sample (n = 143; 13-18 years; 65% female) of students from three high schools (middle/high and low-income areas). Participants completed a PA questionnaire and the Neighbourhood Environment Walkability Scale (NEWS)-Africa and anthropometry measurements. Multivariable linear regression was used to examine various relationships. We found that, compared with adolescents living in middle/high income neighbourhoods, those living in low-income neighbourhoods had lower perceived walkability and PA with higher BMI percentiles. The associations between neighbourhood walkability and PA were inconsistent. In the adjusted models, land use diversity and personal safety were associated with club sports participation, street connectivity was positively associated with school sports PA, and more favourable perceived walkability was negatively associated with active transport. Overall, our findings suggest that the perceived walkability of lower income neighbourhoods is worse in comparison with higher income neighbourhoods, though the association with PA and BMI is unclear.

"I was like intoxicated with this positivity": the politics of hope amongst participants in a trial of a novel spinal cord injury rehabilitation technology in South Africa.

PURPOSE: This study discussed the reports by participants in a randomised controlled trial of a novel intervention for spinal cord injury (SCI) rehabilitation in Cape Town, South Africa. MATERIALS AND METHODS: Sixteen participants were randomised to rehabilitation involving the use of robotic locomotor training, a novel technology, or to a group receiving an activity-based intervention. All participants were interviewed before the intervention and at six months follow-up. RESULTS: In a context in which rehabilitation services for SCI are virtually non-existent, all participants approached the study with enthusiasm and expressed gratitude for participation. They had high hopes for what the programme could achieve, with many believing, perhaps incorrectly, that the programme would help them walk independently again. While hope and enthusiasm are useful for adherence to experimental intervention studies, there is a danger, especially in poorly resourced contexts, for participants to experience considerable disappointment following false hope not being realised. This raises important ethical issues for researchers interested in the potential of new technologies to promote health in poorly resourced contexts. CONCLUSIONS: For clinicians, the path between supporting positive emotions (which may lead to positive outcomes), and confronting unrealistic hope (which may lead to negative outcomes) may be difficult. Follow-up with participants after re-integration into their communities is important to determine long-term psychological impact.Pan African Clinical Trial Number: PACTR201608001647143IMPLICATIONS FOR REHABILITATIONIn low-resource contexts where there is a low level of access to rehabilitation services, such access in the context of a trial of a new intervention may engender hope in a group of people with spinal cord injury. This hope may increase when a new technology is used, as was the case in this study.Hope can be very helpful to people entering rehabilitation, but unrealistic hope and expectations may have negative implications in the longer term.In this study, expectations of participants centred, unrealistically, around regaining the ability to walk again, despite past experiences and medical advice suggesting otherwise.A thin line exists between supporting high expectations and confronting unrealistic hope. This conundrum is difficult for the clinician, as both inappropriate hope and undue pessimism about an intervention have the potential to cause harm.Participant follow-up after the end of any innovative trial is important, not just to monitor physical progress, but also, where necessary, to support participants through a potential period of disillusionment when they find their expectations have not been fully met.

Robotic Walking to Mitigate Bone Mineral Density Decline and Adverse Body Composition in Individuals With Incomplete Spinal Cord Injury: A Pilot Randomized Clinical Trial.

OBJECTIVE: The aim of the study was to determine whether 24 wks of robotic locomotor training or activity-based training was sufficient time to induce bone mineral density and body composition changes in individuals with spinal cord injury. This study reports the secondary analysis of a randomized pilot trial. DESIGN: Participants with chronic motor incomplete tetraplegia ( N = 16) were recruited. Interventions involved 60-min sessions, 3× per week, over 24 wks. Robotic locomotor training involved walking in the Ekso GT suit. Activity-based training involved a combination of resistance, cardiovascular, and weight-bearing exercise. RESULTS: Hip bone mineral density was maintained during robotic locomotor training; however, it was significantly reduced ( P = 0.04, effect size = 0.86) during activity-based training by 0.03 (-0.29 to 0.23) g/cm 2 after intervention. Both interventions improved arm fat-free soft tissue mass, but neither group experienced changes in leg fat-free soft tissue mass. The activity-based training group had a significant decrease in visceral adipose tissue ( P = 0.04, effect size = 0.72) and gynoid fat mass ( P = 0.01, effect size = 0.62). CONCLUSIONS: Twenty-four weeks of robotic locomotor training is possibly a sufficient duration to prevent the progressive decline of bone mineral density usually occurring in this population. A longitudinal period of activity-based training serves as an effective rehabilitation strategy to reduce indices of fat mass in individuals with spinal cord injury.

Robotic Locomotor Training Leads to Cardiovascular Changes in Individuals With Incomplete Spinal Cord Injury Over a 24-Week Rehabilitation Period: A Randomized Controlled Pilot Study.

OBJECTIVE: To describe the effect of robotic locomotor training (RLT) and activity-based training (ABT) on cardiovascular indices during various physiological positions in individuals with spinal cord injury. DESIGN: Randomized controlled pilot study. SETTING: Private practice: Therapy & Beyond Centre - Walking with Brandon Foundation, Sports Science Institute of South Africa, Cape Town, South Africa. PARTICIPANTS: Participants with chronic traumatic motor incomplete tetraplegia (N=16) who resided in the Western Cape, South Africa. INTERVENTION: Robotic locomotor training (Ekso GT) and activity-based training over a 24-week intervention. MAIN OUTCOME MEASURES: Brachial and ankle blood pressure, heart rate, heart rate variability, and cardiovascular efficiency during 4 physiological positions. RESULTS: No differences between groups or over time were evident in resting systolic and diastolic blood pressure, ankle systolic pressure, ankle brachial pressure index, and heart rate variability. Standing heart rate at 24 weeks was significantly higher in the ABT group (95.58±12.61 beats/min) compared with the RLT group (75.14±14.96 beats/min) (P=.05). In the RLT group, no significant changes in heart rate variability (standard deviation R-R interval and root mean square of successive differences) was found between the standing and 6-minute walk test physiological positions throughout the intervention. Cardiovascular efficiency in the RLT group during the 6-minute walk test improved from 11.1±2.6 at baseline to 7.5±2.8 beats per meter walked at 6 weeks and was maintained from 6 to 24 weeks. CONCLUSIONS: Large effect sizes and significant differences between groups found in this pilot study support the clinical effectiveness of RLT and ABT for changing cardiovascular indices as early as 6 weeks and up to 24 weeks of rehabilitation. RLT may be more effective than ABT in improving cardiac responses to orthostatic stress. Based on heart rate variability metrics, the stimulus of standing has comparable effects to RLT on the parasympathetic nervous system. Cardiovascular efficiency of exoskeleton walking improved, particularly over the first 6 weeks. Both the RLT and ABT interventions were limited in their effect on brachial and ankle blood pressure. A randomized controlled trial with a larger sample size is warranted to further examine these findings.

Inter-individual variability in load carriage economy and comparisons between different load conditions.

Equivocal findings exist for the economy associated with load carried close to the body's centre of mass. Individual variation could explain some of the equivocal findings. This research aimed to examine the extent of individual variation in loaded walking economy. Eighteen females carried load on the back, head and split between the front and back. Individual variation in relative load carriage economy (ELI) was primarily assessed using standard deviation, coefficients of variation (CV) and intraclass correlation coefficients (ICC). There was large inter-individual variation in ELI values with highest mean CV's of 16%, 12% and 10% for head-, back- and combined front and back-loading. Mean ELI values were not significantly different between methods. The large amount of individual variation found here suggests future load carriage research should account for individual variation, particularly when considering sample size and when making inferences on the economy associated with different types of load carriage using group mean data.

Effectiveness of over-ground robotic locomotor training in improving walking performance, cardiovascular demands, secondary complications and user-satisfaction in individuals with spinal cord injuries: A systematic review.

OBJECTIVES: To evaluate the effectiveness of over-ground robotic locomotor training in individuals with spinal cord injuries with regard to walking performance, cardiovascular demands, secondary health complications and user-satisfaction. DATA SOURCES: PubMed, Cochrane, Web of Science, Scopus, EBSCOhost and Engineering Village. STUDY SELECTION: Trials in which robotic locomotor training was used for a minimum of 3 participants with spinal cord injury. DATA EXTRACTION: Independent extraction of data by 2 reviewers using a pre-established data abstraction table. Quality of evidence assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE). DATA SYNTHESIS: Total of 27 non-controlled studies representing 308 participants. Most studies showed decreases in exertion ratings, pain and spasticity and reported positive well-being post-intervention. Seven studies were included in meta-analyses on walking performance, showing significant improvements post-intervention (p < 0.05), with pooled effects for the 6-min walking test and 10-metre walking test of-0.94 (95% confidence interval (95% CI) -1.53,-0.36) and -1.22 (95% CI -1.87,-0.57), respectively. The Timed Up and Go Test showed a positive pooled effect of 0.74 (95% CI 0.36, 1.11). Improvements in walking parameters were seen with an increase in session number; however, no significant cardiovascular changes were found over time. CONCLUSION: Robotic locomotor training shows promise as a tool for improving neurological rehabilitation; however, there is limited evidence regarding its training benefits. Further high-powered, randomized controlled trials, with homogenous samples, are required to investigate these effects.

A comparison of economy and sagittal plane trunk movements among back-, back/front- and head-loading.

It has been suggested that freedom of movement in the trunk could influence load carriage economy. This study aimed to compare the economy and sagittal plane trunk movements associated with three load carriage methods that constrain posture differently. Eighteen females walked at 3 km.h-1 with loads of 0, 3, 6, 9, 12, 15 and 20 kg carried on the back, back/front and head. Load carriage economy was assessed using the Extra Load Index (ELI). Change in sagittal plane trunk forward lean and trunk angle excursion from unloaded to loaded walking were assessed. Results show no difference in economy between methods (p = .483), despite differences in the change in trunk forward lean (p = .001) and trunk angle excursion (p = .021) from unloaded to loaded walking. We conclude that economy is not different among the three methods of load carriage, despite significant differences in sagittal plane trunk movements. Practitioner summary: This article shows, based on mean data, that there is no difference in economy among back, back/front and head-loading, despite differences in trunk movement. It is possible a combination of factors align to influence individual economy, rather than a single set of factors, applicable to all individuals for each method.

Neuromuscular changes associated with superior fatigue resistance in African runners.

BACKGROUND: An enhanced ability to resist fatigue has been proposed as one of African runners' performance superiority sources, although their fatigue resistance during sustained non-running-specific activities remain unclear. This study aimed to compare fatigue resistance during sustained isometric exercise between performance-matched African and European runners. METHODS: Thirty long-distance runners (16 African, 14 European) performed submaximal fatiguing sustained isometric knee extensions. Rectus femoris electromyographic (EMG) activity was measured, and the muscle was electrically stimulated to contract at the beginning and end of the test. RESULTS: Time to task failure was greater for African than European runners (269±115 vs. 193±52 s, P=0.002; effect size [ES]=0.85, large effect). During the test, EMG amplitude increased less over time (P=0.031), and the left shift in the EMG frequency spectrum was less over time for the African runners (P<0.001). In addition, there was a lower relative reduction in stimulated force output from the first to the second stimulation in African runners (17.75±14.95 vs. 37.89±14.78%, P=0.006; ES=1.35; large effect). CONCLUSIONS: These findings of greater fatigue resistance during non-running-specific activity and the associated muscle recruitment profile may contribute to the understanding of the physiology underlying endurance performance in African runners.

Quality of life in individuals living with HIV/AIDS attending a public sector antiretroviral service in Cape Town, South Africa.

BACKGROUND: Health related quality of life (HRQoL) is an important outcome helping to understand the impact of antiretroviral therapy (ART). We examined and compared the HRQoL in relation to ART status among HIV-infected patients in a public sector service in Cape Town, South Africa. In addition, we aimed to examine the relationship between ART status and HRQoL according to CD4 count strata. METHODS: A cross sectional study sample of 903 HIV-infected patients who were categorized as not receiving ART (ART-naïve) or receiving first-line ART for > 6 months (ART). HRQoL outcomes were compared in the two groups. HRQoL was assessed using the EQ-5D (five domains) and Visual Analogue Scale (EQ-5D VAS). RESULTS: Of the total sample, 435 were categorised as ART naïve (76% women) and 468 were on ART (78% women). There were no significant associations between groups for most of the EQ-5D domains, however ART-naïve experienced a significantly greater problem with mobility than the ART group. Being ART-naïve (adjusted odds ratio (aOR) 3.08 95% confidence interval (CI) 1.63- 7.89) and obese 2.78 (95% CI 1.24- 6.22) were identified as predictors for increased mobility problems in multivariate analysis. In addition, receiving ART (5.61 difference; 95% CI 2.50 - 8.72) and having some source of income (4.76; 95% CI 1.63 -7.89) were identified as predictors for a higher EQ-5D VAS score. When grouped according to CD4 count strata, there were no significant difference between groups for most of the EQ-5D domains, however the ART-naïve group indicated having significantly greater problems under the CD4 count of >500 cells/µL in the anxiety/depression domain (22.4% vs 8.8%, p = 0.018) and significantly lower EQ-5D VAS scores under the CD4 counts of ≤ 200 cells/µL (median 80 (IQR 60-90) vs 90 (IQR 80-100), p = 0.0003) and 201-350 cells/µL (median 80 (IQR 70-90) vs 90 (80-100), p = 0.0004) compared to ART group. CONCLUSIONS: HRQoL (self-rated health state) was improved with ART use, including those with immunocompromised status, which may be relevant to the public sector ART program in South Africa.

Effect of different antiretroviral drug regimens on body fat distribution of HIV-infected South African women.

No African studies have examined the effect of first-line nonnucleoside reverse transcriptase inhibitor (NNRTI)-based and second-line protease inhibitor (PI)-based antiretroviral therapy (ART) on body composition. We compared body composition in HIV-infected black South African women receiving NNRTI-based ART (ART1, n=344), PI-based ART (ART2, n=91), and those not on ART (ART-naive, n=309). Accordingly, body composition was measured using dual energy x-ray absorptiometry (DXA) and anthropometry in a cross-sectional study. Despite similar body mass index (BMI), ART1 and ART2 had greater central fat mass (FM) [median (IQR): 44.2 (39.4-50.1) and 46.9 (39.3-52.8) vs. 41.1 (36.3-45.2) %FM, p<0.01] and less leg FM [41.2 (34.8-45.8) and 40.2 (32.9-45.7) vs. 43.9 (39.3-48.1) %FM, p<0.01] than ART-naive women. Within ART1, waist:hip was greater [0.87 (0.81-0.92) vs. 0.84 (0.78-0.89), p=0.006], while calf skinfold was lower [15.2 (9.4-21.5) vs. 17.4 (12.0-23.6) mm, p=0.033] in women receiving efavirenz compared to nevirapine. ART2 had a greater waist:hip, and abdominal, subscapular, and suprailiac skinfolds than ART1 (p<0.05). After adjusting for time on d4T (stavudine), ART2 had greater body fat than ART1 (p<0.05). With increasing time on d4T, the decrease in leg fat (%FM) was higher in ART1 than ART2 (p=0.012, for time×treatment effect). A similar interaction was reported for total time on ART treatment (p=0.002 for time×treatment effect). In conclusion, ART was associated with increased central fat and reduced peripheral fat. Changing to a PI-based regimen in ART2, which also substitutes stavudine with zidovudine, partially reversed the peripheral fat loss observed on ART1.

Effect of nonnucleoside reverse transcriptase inhibitor-based antiretroviral therapy on dysglycemia and insulin sensitivity in South African HIV-infected patients.

BACKGROUND: Data on the prevalence of the complications of antiretroviral therapy (ART) (diabetes, central fat accumulation, peripheral fat wasting, and dyslipidemia) in sub-Saharan Africa are sparse. We examined the prevalence and associated risk factors of dysglycemia and insulin sensitivity in HIV-infected South Africans. METHODS: HIV-infected patients, on nonnucleoside reverse transcriptase inhibitor-based ART or ART-naive, had oral glucose tolerance tests and clinical anthropometry. Insulin sensitivity and ß-cell function were assessed. RESULTS: The prevalence of dysglycemia in 406 ART-naive patients and 443 patients on ART was 25.7% and 21.9% (P = 0.193), respectively. Dysglycemic patients on ART had a similar body mass index (P = 0.440), greater waist circumference (P = 0.047), and smaller calf skinfold thickness (P = 0.015) than dysglycemic ART-naive patients but no difference in ß-cell function or insulin sensitivity. Normoglycemic patients on ART had a greater body mass index (P = 0.0009), waist circumference (P = 0.0001), and abdominal skinfold thickness (P = 0.040), similar calf skinfold thickness (P = 0.079), and reduced ß-cell function [lower insulinogenic index (P = 0.027) and oral disposition index (D(o), P = 0.020)] compared with normoglycemic ART-naive patients. In multivariate analysis, older age [odds ratio (OR): 1.04, 95% confidence interval (CI): 1.02 to 1.06], male gender (OR: 1.96, 95% CI: 1.28 to 2.99), higher CD4 count (OR: 1.0, 95% CI: 1.00 to 1.02) and use of efavirenz (OR: 1.70, 95% CI: 1.19 to 2.45) were associated with dysglycemia. CONCLUSIONS: The prevalence of dysglycemia in ART-naive and ART patients was similar. Peripheral fat wasting was more common in dysglycemic patients on ART. The association of efavirenz with dysglycemia is important because first-line ART regimens in the developing world include nonnucleoside reverse transcriptase inhibitors, and increasingly, efavirenz is selected because of its perceived lower toxicity than nevirapine.

Differential effects of abdominal adipose tissue distribution on insulin sensitivity in black and white South African women.

Black South African women are more insulin resistant than BMI-matched white women. The objective of the study was to characterize the determinants of insulin sensitivity in black and white South African women matched for BMI. A total of 57 normal-weight (BMI 18-25 kg/m(2)) and obese (BMI > 30 kg/m(2)) black and white premenopausal South African women underwent the following measurements: body composition (dual-energy X-ray absorptiometry), body fat distribution (computerized tomography (CT)), insulin sensitivity (S(I), frequently sampled intravenous glucose tolerance test), dietary intake (food frequency questionnaire), physical activity (Global Physical Activity Questionnaire), and socioeconomic status (SES, demographic questionnaire). Black women were less insulin sensitive (4.4 +/- 0.8 vs. 9.5 +/- 0.8 and 3.0 +/- 0.8 vs. 6.0 +/- 0.8 x 10(-5)/min/(pmol/l), for normal-weight and obese women, respectively, P < 0.001), but had less visceral adipose tissue (VAT) (P = 0.051), more abdominal superficial subcutaneous adipose tissue (SAT) (P = 0.003), lower SES (P < 0.001), and higher dietary fat intake (P = 0.001) than white women matched for BMI. S(I) correlated with deep and superficial SAT in both black (R = -0.594, P = 0.002 and R = 0.495, P = 0.012) and white women (R = -0.554, P = 0.005 and R = -0.546, P = 0.004), but with VAT in white women only (R = -0.534, P = 0.005). In conclusion, body fat distribution is differentially associated with insulin sensitivity in black and white women. Therefore, the different abdominal fat depots may have varying metabolic consequences in women of different ethnic origins.

Insulin response in relation to insulin sensitivity: an appropriate beta-cell response in black South African women.

OBJECTIVE: The purpose of this study was to characterize differences in the acute insulin response to glucose (AIR(g)) relative to insulin sensitivity (S(I)) in black and white premenopausal normoglycemic South African women matched for body fatness. RESEARCH DESIGN AND METHODS: Cross-sectional analysis including 57 black and white South African women matched for BMI, S(I), AIR(g), and the disposition index (AIR(g) x S(I)) were performed using a frequently sampled intravenous glucose tolerance test with minimal model analysis, and similar measures were analyzed using an oral glucose tolerance test (OGTT). Body composition was assessed by dual-energy X-ray absorptiometry and computed tomography. RESULTS: S(I) was significantly lower (4.4 +/- 0.8 vs. 9.4 +/- 0.8 and 2.9 +/- 0.8 vs. 6.0 +/- 0. 8 x 10(-5) min(-1)/[pmol/l], P < 0.001) and AIR(g) was significantly higher (1,028 +/- 255 vs. 352 +/- 246 and 1,968 +/- 229 vs. 469 +/- 246 pmol/l, P < 0.001), despite similar body fatness (30.9 +/- 1.4 vs. 29.7 +/- 1.3 and 46.8 +/- 1.2 vs. 44.4 +/- 1.3%) in the normal-weight and obese black women compared with their white counterparts, respectively. Disposition index, a marker of beta-cell function, was not different between ethnic groups (3,811 +/- 538 vs. 2,966 +/- 518 and 3,646 +/- 485 vs. 2,353 +/- 518 x 10(-5) min, P = 0.10). Similar results were obtained for the OGTT-derived measures. CONCLUSIONS: Black South African women are more insulin resistant than their white counterparts but compensate by increasing their insulin response to maintain normal glucose levels, suggesting an appropriate beta-cell response for the level of insulin sensitivity.

Conjugated linoleic acid versus high-oleic acid sunflower oil: effects on energy metabolism, glucose tolerance, blood lipids, appetite and body composition in regularly exercising individuals.

The aim of this study was to measure the effects of 12 weeks of conjugated linoleic acid (CLA) supplementation on body composition, RER, RMR, blood lipid profiles, insulin sensitivity and appetite in exercising, normal-weight persons. In this double-blind, randomised, controlled trial, sixty-two non-obese subjects (twenty-five men, thirty-seven women) received either 3.9 g/d CLA or 3.9 g high-oleic acid sunflower oil for 12 weeks. Prior to and after 12 weeks of supplementation, oral glucose tolerance, blood lipid concentrations, body composition (dual-energy X-ray absorptiometry and computerised tomography scans), RMR, resting and exercising RER and appetite were measured. There were no significant effects of CLA on body composition or distribution, RMR, RER or appetite. During the oral glucose tolerance tests, mean plasma insulin concentrations (0, 30, 120 min) were significantly lower (P= 0.04) in women who supplemented with CLA (24.3 (SD 9.7) to 20.4 (SD 8.5) microU/ml) compared to high-oleic acid sunflower oil control (23.7 (SD 9.8) to 26.0 (SD 8.8) microU/ml). Serum NEFA levels in response to oral glucose were attenuated in both men and women in the CLA (P=0.001) compared to control group. However, serum total cholesterol and LDL-cholesterol concentrations decreased in both groups and HDL-cholesterol concentrations decreased in women over 12 weeks (P=0.001, P=0.02, P=0.02, respectively). In conclusion, mixed-isomer CLA supplementation had a favourable effect on serum insulin and NEFA response to oral glucose in non-obese, regularly exercising women, but there were no CLA-specific effects on body composition, energy expenditure or appetite.

Effects of elevated plasma adrenaline levels on substrate metabolism, effort perception and muscle activation during low-to-moderate intensity exercise.

The aim of this study was to differentiate the role of raised plasma adrenaline (Adr) concentrations from sympathoadrenal activation associated with moderate-intensity exercise, on muscle activation, cardiopulmonary responses, fuel metabolism, and ratings of perceived exertion (RPE) during low-intensity exercise. Two groups of subjects (MOD, n=6; LOW, n=7) cycled on two occasions for 90 min. MOD cycled at 68% VO(2max) with saline infusion, and at 34% VO(2max) with Adr infusion. LOW cycled twice at 34% VO(2max), with either Adr or saline infusion. Infusions (0.015 g Adr/kg/min) started at 15 min and increased plasma [Adr] somewhat higher than during exercise at 68% VO(2max) (approximately 1.9 vs. 1.4 nM, at 75 min). Mean plasma glucose and lactate concentrations during LOW were significantly higher with Adr than saline infusion (5.1+/-0.6 vs. 4.4+/-0.3 mmol/l, P<0.01 and 2.1+/-0.8 vs. 1.3+/-0.5 mmol/l, P<0.01, respectively). Elevated [Adr], without increased exercise intensity, did not alter glycogenolysis. There were also no effects of Adr infusion at 34% VO(2max) on heart rate, oxygen consumption, [FFA], respiratory exchange ratio, intramuscular triglyceride utilization, muscle activation or RPE. In conclusion, elevated [Adr] similar to those found during moderate-intensity exercise increased plasma glucose and lactate availability, but did not alter intramuscular fuel utilization, effort perception or muscle activation.

Submaximal force production during perceptually guided isometric exercise.

The aim of this study was to examine submaximal isometric force production guided by perceptual feelings of exertion. Thirty young adults performed isometric knee extensions on an isokinetic dynamometer. Subjects performed five different tests; the first test was the same for all subjects (standard naïve test). During the standard naïve test, subjects were asked to randomly produce force at perceived contraction intensities (25%, 50% and 75% of their maximum voluntary contraction (MVC)), with 100% MVC performed as the final intensity. All intensities, including the 100% MVC, were randomly performed in the other four tests (control tests 1 and 2, post 20% MVC and post 100% MVC tests). Post 20% MVC and post 100% MVC tests included fatiguing isometric exercise at 20% and 100% MVC respectively, which were performed prior to the test protocol. Results show that absolute peak force increased with increasing intensity (P<0.001) during all tests. During the standard naïve test, absolute peak force at 25% and 50% MVC was significantly lower (P=0.009) compared to control test 2, post 20% MVC and 100% MVC tests, and relative peak force was lower at all intensities compared to all other tests (P<0.001). Absolute and relative peak force was most accurate at 50% MVC (-12.06 N and -2.42%, respectively). Prior fatiguing isometric exercise did not affect the subsequent perceptual response range. In conclusion, isometric force was most accurate at 25% MVC but under-produced (perceptually overestimated) during higher contraction intensities preceding a maximal voluntary contraction (100% MVC). The ability to match absolute force with target contraction intensities was most accurate at 50% MVC during all five experimental conditions and poor at opposite ends of the force domain. Furthermore, prior fatiguing isometric exercise did not have an effect on the subsequent perceptual response range.