Far from the walking pace. Ecological and evolutionary consequences of the suboptimal locomotion speeds in non-adult humans.

INTRODUCTION: Locomotion activities are part of most human daily tasks and are the basis for subsistence activities, particularly for hunter-gatherers. Therefore, differences in speed walking-related variables may have an effect, not only on the mobility of the group, but also on its composition. Some anthropometric parameters related to body length could affect walking speed-related variables and contribute to different human behaviors. However, there is currently little information on the influence of these parameters in nonadult individuals. METHODS: Overall, 11 females and 17 male child/adolescents, 8-17 years of age, volunteered to participate in this cross-sectional study. Five different pace walking tests were performed on a treadmill to calculate the optimal locomotion speed (OLS) and U-shaped relationship between the walking energy expenditure and speed (χ2 cost of transport [CoT]) (i.e., energetic walking flexibility). RESULTS: The mean OLS was 3.05 ± 0.13 miles per hour (mph), with no differences between sexes. Similarly, there were no sex differences in walking flexibility according to the χ2 CoT. Body height (p < .0001) and femur length (p < .001) were positively correlated with χ2 CoT; however, female child/adolescents mitigated the effect of height and femur length when walking at suboptimal speeds. CONCLUSION: Consistent with prior observations in adults, our findings suggest that anthropometric parameters related to body stature are associated with reduced suboptimal walking flexibility in children and adolescents. Taken together, these results suggest that children and adolescents can adapt their pace to the one of taller individuals without a highly energetic penalty, but this flexibility decreases with increasing body size.

Validation of predictive equations to estimate resting metabolic rate of females and males across different activity levels.

OBJECTIVES: Using equations to predict resting metabolic rate (RMR) has yielded different degrees of validity, particularly when sex and different physical activity levels were considered. Therefore, the purpose of the present study was to determine the validity of several different predictive equations to estimate RMR in female and male adults with varying physical activity levels. METHOD: We measured the RMR of 50 adults (26 females and 24 males) evenly distributed through activity levels varying from sedentary to ultra-endurance. Body composition was measured by dual X-ray absorptiometry and physical activity was monitored by accelerometry. Ten equations to predict RMR were applied (using Body Mass [BM]: Harris & Benedict, 1919; Mifflin et al., 1990 [MifflinBM]; Pontzer et al., 2021 [PontzerBM]; Schofield, 1985; FAO/WHO/UNU, 2004; and using Fat-Free Mass (FFM): Cunningham, 1991; Johnstone et al., 2006; Mifflin et al., 1990 [MifflinFFM]; Nelson et al. 1992; Pontzer et al., 2021 [PontzerFFM]). The accuracy of these equations was analyzed, and the effect of sex and physical activity was evaluated using different accuracy metrics. RESULTS: Equations using BM were less accurate for females, and their accuracy was influenced by physical activity and body composition. FFM equations were slightly less accurate for males but there was no obvious effect of physical activity or other sample parameters. PontzerFFM provides higher accuracy than other models independent of the magnitude of RMR, sex, activity levels, and sample characteristics. CONCLUSION: Equations using FFM were more accurate than BM equations in our sample. Future studies are needed to test the accuracy of RMR prediction equations in diverse samples.

Short-term changes in added sugar consumption by adolescents reflected in the carbon isotope ratio of fingerstick blood.

BACKGROUND: Consumption of added sugars (AS) and sugar-sweetened beverages (SSB) may adversely affect adolescents' weight and cardiovascular disease risk. Reliance on self-reported dietary assessment methods is a common research limitation, which could be overcome by dietary intake biomarkers. AIM: The investigation was a proof-of-concept study to evaluate the proposed carbon isotope ratio (δ13C) biomarker of AS intake in adolescents, using a controlled feeding design. METHODS: Participants (n = 33, age 15.3 years, 53% female) underwent two seven-day controlled feeding periods in a randomly assigned order. Diets were matched in composition except for AS content (5% or 25% of total energy). Fasting fingerstick blood samples were collected daily during each diet period. RESULTS: Fingerstick δ13C values changed from day 1 to 8 by -0.05 ± 0.071‰ on 5% AS, and +0.03 ± 0.083‰ on 25% AS (p ≤ 0.001). Reliability was demonstrated between day 7 and 8 δ13C values on the 5% (ICC = 0.996, p ≤ 0.001) and 25% (ICC = 0.997, p ≤ 0.001) AS diets. CONCLUSIONS: Larger scale investigations are warranted to determine if this technique could be applied to population-level research in order to help assess the effectiveness of interventions aimed at reducing the consumption of AS or SSB intake.

Questionnaires for outcome expectancy, self-regulation, and behavioral expectation for resistance training among young-old adults: development and preliminary validity.

The purpose of the present research was to develop questionnaires to assess outcome expectancy for resistance training (RT), behavioral expectation in the context of perceived barriers to RT, and self-regulation strategies for RT among young-old adults (50-69 years). Measurement development included (a) item generation through elicitation interviews (N = 14) and open-ended questionnaires (N = 56), (b) expert feedback on a preliminary draft of the questionnaires (N = 4), and (c) a quantitative longitudinal study for item-reduction and psychometric analyses (N = 94). Elicitation procedures, expert feedback, and item reduction yielded four questionnaires with a total of 33 items. Positive outcome expectancy (α = .809), negative outcome expectancy (α = .729), behavioral expectation (α = .925), and self-regulation (α = .761) had-with one exception-moderate bivariate associations with two different indicators of self-reported RT behavior at one-month follow-up (r = .298 to .506). The present research provides preliminary support for newly developed questionnaires to facilitate understanding of the psychosocial determinants of RT among young-old adults.

A Randomized Trial of Healthy Weight Gain in Athletic Individuals.

PURPOSE: The purpose of this study is to evaluate the outcomes of a 10-wk diet and exercise regimen designed to promote healthy weight gain with excess energy from peanut-containing or high-carbohydrate foods. METHODS: Nineteen male and 13 female athletes were randomly assigned to receive an additional 500 kcal·d -1 above typical intake through provision of either peanut-based whole foods/snacks (PNT group) or a similar, high-carbohydrate, peanut-free snack (CHO group) along with supervised, whole-body RT (3 d·wk -1 for 60-120 min). Body composition was assessed by dual-energyx-ray absorptiometry at baseline and postintervention. RESULTS: Total body mass (TBM) increased 2.2 ± 1.3 kg with 1.5 ± 1.1 kg as LBM after week 10. The PNT group ( n = 16; 27 ± 7 yr; 10 men, 6 women) gained less TBM than the CHO group ( n = 16; 23 ± 3 yr; 9 men, 7 women) (1.6 ± 1.1 kg vs 2.7 ± 1.2 kg, respectively, P = 0.007) with no differences in LBM (1.2 ± 1.1 kg vs 1.9 ± 1.0 kg, P = 0.136). CONCLUSIONS: These results suggest that the addition of 500 kcal·d -1 from whole foods/snacks in combination with a rigorous RT program promotes a similar weight gain of ~0.22 kg·wk -1 , primarily as LBM, over 10 wk in both male and female athletes. However, snack macronutrient content may impact the effectiveness of this regimen.

Validity of predictive equations for total energy expenditure against doubly labeled water.

Variations in physical activity energy expenditure can make accurate prediction of total energy expenditure (TEE) challenging. The purpose of the present study was to determine the accuracy of available equations to predict TEE in individuals varying in physical activity (PA) levels. TEE was measured by DLW in 56 adults varying in PA levels which were monitored by accelerometry. Ten different models were used to predict TEE and their accuracy and precision were evaluated, considering the effect of sex and PA. The models generally underestimated the TEE in this population. An equation published by Plucker was the most accurate in predicting the TEE in our entire sample. The Pontzer and Vinken models were the most accurate for those with lower PA levels. Despite the levels of accuracy of some equations, there were sizable errors (low precision) at an individual level. Future studies are needed to develop and validate these equations.

Repeated-bout exercise in the heat in young athletes: physiological strain and perceptual responses.

A short recovery period between same-day competitions is common practice in organized youth sports. We hypothesized that young athletes will experience an increase in physiological strain and perceptual discomfort during a second identical exercise bout in the heat, with 1 h (21 degrees C) between bouts, even with ample hydration. Twenty-four athletes (6 boys and 6 girls: 12-13 yr old, 47.7 +/- 8.3 kg; 6 boys and 6 girls: 16-17 yr old, 61.0 +/- 8.6 kg) completed two 80-min intermittent exercise bouts (treadmill 60%, cycle 40% peak oxygen uptake) in the heat (33 degrees C, 48.9 +/- 6.1% relative humidity). Sweat loss during each bout was similar within each age group (12-13 yr old: bout 1, 943.6 +/- 237.1 ml; bout 2, 955.5 +/- 250.3 ml; 16-17 yr old: bout 1, 1,382.2 +/- 480.7 ml; bout 2, 1,373.1 +/- 472.2 ml). Area under the curve (AUC) was not statistically different (P > 0.05) between bouts for core body temperature (12-13 yr old: bout 1 peak, 38.6 +/- 0.4 degrees C; bout 2, 38.4 +/- 0.2 degrees C; 16-17 yr old: bout 1 peak, 38.8 +/- 0.7 degrees C; bout 2, 38.7 +/- 0.6 degrees C), physiological strain index (12-13 yr old: bout 1 peak, 7.9 +/- 0.9; bout 2, 7.5 +/- 0.7; 16-17 yr old: bout 1 peak, 8.1 +/- 1.5; bout 2, 7.9 +/- 1.4), or thermal sensation for any age/sex subgroup or for all subjects combined. However, rating of perceived exertion AUC and peak were higher (P = 0.0090 and 0.0004, respectively) during bout 2 in the older age group. Notably, four subjects experienced consistently higher responses throughout bout 2. With these healthy, fit, young athletes, 1 h of complete rest, cool down, and rehydration following 80 min of strenuous exercise in the heat was generally effective in eliminating any apparent carryover effects that would have resulted in greater thermal and cardiovascular strain during a subsequent identical exercise bout.

Femoral artery diameter and arteriogenic cytokines in healthy women.

Animal studies have identified monocyte chemoattractive protein-1 (MCP-1) and vascular endothelial growth factor (VEGF) as critical mediators of arterial diameter enlargement in response to chronic increases in blood flow (arteriogenesis). Furthermore, cellular studies have shown that the shear stresses resulting from increased blood flow stimulate synthesis of MCP-1, which in turn stimulates synthesis of VEGF. The purpose of this study was to determine if these mechanisms are evident in healthy women. Resting femoral artery diameter and blood flow, lean leg mass, MCP-1 and VEGF concentrations, and aerobic capacity were measured in 34 healthy women along with plasma concentrations of lipids associated with cardiovascular disease risk. Femoral artery diameter was independently related to metabolically active (lean) leg mass (b=0.41, P=0.008) and aerobic capacity (b=0.45, P=0.004). Plasma MCP-1 correlated negatively with the ratio of femoral artery diameter to lean leg mass (b=-0.42, P=0.009) and positively with serum triglycerides (b=0.46, P=0.005). Plasma VEGF exhibited similar correlations and strongly correlated with MCP-1 (R=0.92, P<0.0001). The results indicate that circulating MCP-1 and VEGF concentrations are associated with both arteriogenic and atherogenic stimuli in healthy women.

Resistance training is associated with spontaneous changes in aerobic physical activity but not overall diet quality in adults with prediabetes.

BACKGROUND: Aerobic exercise interventions have been shown to result in alterations to dietary intake and non-exercise physical activity (PA). To date, the ability for resistance training (RT) to influence other health-related behaviors has not been examined. This study aimed to determine if initiation and maintenance of RT is associated with spontaneous changes in dietary quality and non-RT PA in adults with prediabetes. METHODS: Overweight/obese adults (n=170, BMI=32.9±3.8kg·m2, age=59.5±5.5years, 73% female) with prediabetes were enrolled in the 15-month Resist Diabetes trial. Participants completed a supervised 3-month RT initiation phase followed by a 6-month maintenance phase and a 6-month no-contact phase. Participants were not encouraged to change eating or non-RT PA behaviors. At baseline, and months 3, 9, and 15, three 24-hour diet recalls were collected to evaluate dietary intake and quality, the Aerobics Institute Longitudinal Study Questionnaire was completed to evaluate non-RT PA, and body mass, body composition (DXA), and muscular strength were measured. At months 3, 9, and 15 social cognitive theory (SCT) constructs were assessed with a RT Health Beliefs Questionnaire. Mixed effects models were used to assess changes in dietary intake and non-RT PA over the 15-month study period. RESULTS: Energy and carbohydrate intake decreased with RT initiation and maintenance phases (baseline to month 9: ß=-87.9, p=0.015 and ß=-16.3, p<0.001, respectively). No change in overall dietary quality (Healthy Eating Index [HEI]-2010 score: ß=-0.13, p=0.722) occurred, but alterations in HEI-2010 sub-scores were detected. Maintenance of RT was accompanied by an increase in MET-min/week of total non-RT PA (month 3 to month 9: ß=146.2, p=0.01), which was predicted by increased self-regulation and decreased negative outcome expectancies for RT (ß=83.7, p=0.014 and ß=-70.0, p=0.038, respectively). CONCLUSIONS: Initiation and maintenance of RT may be a gateway behavior leading to improvements in other health-related behaviors. These results provide rationale for single-component lifestyle interventions as an alternative to multi-component interventions, when resources are limited.

Resist diabetes: A randomized clinical trial for resistance training maintenance in adults with prediabetes.

OBJECTIVE: To determine whether a social cognitive theory (SCT)-based intervention improves resistance training (RT) maintenance and strength, and reduces prediabetes prevalence. RESEARCH DESIGN AND METHODS: Sedentary, overweight/obese (BMI: 25-39.9 kg/m2) adults aged 50-69 (N = 170) with prediabetes participated in the 15-month trial. Participants completed a supervised 3-month RT (2×/wk) phase and were randomly assigned (N = 159) to one of two 6-month maintenance conditions: SCT or standard care. Participants continued RT at a self-selected facility. The final 6-month period involved no contact. Assessments occurred at baseline and months 3, 9, and 15. The SCT faded-contact intervention consisted of nine tailored transition (i.e., supervised training to training alone) and nine follow-up sessions. Standard care involved six generic follow-up sessions. Primary outcomes were prevalence of normoglycemia and muscular strength. RESULTS: The retention rate was 76%. Four serious adverse events were reported. After 3 months of RT, 34% of participants were no longer prediabetic. This prevalence of normoglycemia was maintained through month 15 (30%), with no group difference. There was an 18% increase in the odds of being normoglycemic for each % increase in fat-free mass. Increases in muscular strength were evident at month 3 and maintained through month 15 (P<0.001), which represented improvements of 21% and 14% for chest and leg press, respectively. Results did not demonstrate a greater reduction in prediabetes prevalence in the SCT condition. CONCLUSIONS: Resistance training is an effective, maintainable strategy for reducing prediabetes prevalence and increasing muscular strength. Future research which promotes RT initiation and maintenance in clinical and community settings is warranted. TRIAL REGISTRATION: ClinicalTrials.gov NCT01112709.

Psychosocial mediators of a theory-based resistance training maintenance intervention for prediabetic adults.

OBJECTIVE: Examine psychosocial mediators of the effects of high vs. low-dose resistance training (RT) maintenance interventions among older (ages 50-69), overweight and pre-diabetic adults. DESIGN: Participants (N = 123) completed a three-month supervised RT initiation phase and were subsequently randomised (time 1) to high or low-dose six-month unsupervised RT maintenance interventions (time 2), followed by a six-month no-contact phase (time 3). MAIN OUTCOME MEASURES: Online measures of putative mediators and RT behaviour. RESULTS: RT intervention condition (high vs. low dose) had significant effects on change from time 1 to time 2 in behavioural expectation, self-regulation and perceived satisfaction (f(2) = .04-.08), but not outcome expectancies, RT strategies or behavioural intentions (f(2) ≤ .02). Change in each of the putative mediators, except for outcome expectancies (f(2) ≤ .02), had significant effects on RT behaviour at times 2 (f(2) = .12-.27) and 3 (f(2) = .23-.40). In a multiple mediation model, behavioural expectation (f(2) = .11) and self-regulation (f(2) = .06) mediated the effects of RT intervention condition on time 2 RT behaviour, whereas perceived satisfaction did not (f(2) = .01). Self-regulation was a significant mediator of intervention effects on time 3 RT behaviour (f(2) = .11), but behavioural expectation and perceived satisfaction were not (f(2) = .04). CONCLUSIONS: Findings suggest that behavioural expectation and self-regulation are appropriate targets for RT maintenance interventions among at-risk older adults.

Prediabetes Phenotype Influences Improvements in Glucose Homeostasis with Resistance Training.

PURPOSE: To determine if prediabetes phenotype influences improvements in glucose homeostasis with resistance training (RT). METHODS: Older, overweight individuals with prediabetes (n = 159; aged 60±5 yrs; BMI 33±4 kg/m2) completed a supervised RT program twice per week for 12 weeks. Body weight and composition, strength, fasting plasma glucose, 2-hr oral glucose tolerance, and Matsuda-Defronza estimated insulin sensitivity index (ISI) were assessed before and after the intervention. Participants were categorized according to their baseline prediabetes phenotype as impaired fasting glucose only (IFG) (n = 73), impaired glucose tolerance only (IGT) (n = 21), or combined IFG and IGT (IFG/IGT) (n = 65). RESULTS: Chest press and leg press strength increased 27% and 18%, respectively, following the 12-week RT program (both p<0.05). Waist circumference (-1.0%; pre 109.3±10.3 cm, post 108.2±10.6 cm) and body fat (-0.6%; pre 43.7±6.8%, post 43.1±6.8%) declined, and lean body mass (+1.3%; pre 52.0±10.4 kg, post 52.7±10.7 kg) increased following the intervention. Fasting glucose concentrations did not change (p>0.05) following the intervention. However, 2-hr oral glucose tolerance improved in those with IGT (pre 8.94±0.72 mmol/l, post 7.83±1.11 mmol/l, p<0.05) and IFG/IGT (pre 9.66±1.11mmol/l, post 8.60±2.00 mmol/l) but not in those with IFG (pre 6.27±1.28mmol/l, post 6.33± 1.55 mmol/l). There were no significant changes in ISI or glucose area under the curve following the RT program. CONCLUSIONS: RT without dietary intervention improves 2-hr oral glucose tolerance in individuals with prediabetes. However, the improvements in glucose homeostasis with RT appear limited to those with IGT or combined IFG and IGT. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01112709.

Theory-based approach for maintaining resistance training in older adults with prediabetes: adherence, barriers, self-regulation strategies, treatment fidelity, costs.

Effectively preventing and treating chronic diseases through health behavior changes often require intensive theory- and evidence-based intervention including long-term maintenance components. We assessed the efficacy of theory-based maintenance approaches varying by dose for persistently performing resistance training (RT) with the hypothesis that a higher-dose social cognitive theory (SCT) approach would produce greater RT adherence than lower-dose Standard. The Resist-Diabetes study first established 2×/week resistance training (RT) in a 3-month supervised intervention in older (50-69 years, N = 170), overweight to obese (BMI 25-39.9 kg/m(2)) previously inactive adults who fit prediabetes criteria (fasting glucose concentration = 95-125 mg/dl; oral glucose tolerance test 2-h glucose concentration = 140-199 mg/dl or both). After the supervised phase, participants (N = 159) were then randomly assigned to one of two conditions for transition (3 weeks) and then RT alone in community settings for extended contact, maintenance (6 months), and then no contact (6 months). SCT featured continued tailored, interactive personal, and web-based check-ups focused on RT, self-regulation, and a barrier/strategies approach. Standard involved low-dose, generic personal, and web-based check-ups within the same theoretical approach. SCT and Standard both resulted in similar RT, 2×/week adherence during maintenance (74.4 %) and no-contact phases (53.1 %). Cost analysis indicated the Standard intervention for transition and maintenance was inexpensive ($160). Standard can be translated into practice with the potential for continuous contact and persistence in RT beyond the typical program maintenance phase.

Angiotensin II receptor blockade and skeletal muscle metabolism in overweight and obese adults with elevated blood pressure.

OBJECTIVES: Whether angiotensin II receptor blockade improves skeletal muscle fatty acid oxidation in overweight and obese humans is unknown. The purpose of the study was to test the hypothesis that the angiotensin II receptor blocker, olmesartan, would increase fatty acid oxidation and the activity of enzymes associated with oxidative metabolism in skeletal muscle of overweight and obese humans. METHODS: A total of 12 individuals (6 men and 6 women) aged 18-75 and with a body mass index ⩾25 kg/m2 were assigned to olmesartan or placebo for 8 weeks in a crossover fashion. Fatty acid oxidation was measured before and after each intervention by counting the (14)CO2 produced from [1-(14)C] palmitic acid in skeletal muscle homogenates. RESULTS: Fatty acid oxidation was not significantly different between treatment periods at baseline and post intervention. In addition, the enzyme activities of citrate synthase and ß-hydroxyacyl-coenzyme A dehydrogenase in skeletal muscle homogenates did not differ between treatment periods at baseline or post intervention. CONCLUSIONS: Treatment with olmesartan for 8 weeks does not improve fatty acid oxidation or the activity of enzymes associated with oxidative metabolism in skeletal muscle from overweight and obese individuals. Taken together, our results indicate that improvements in skeletal muscle metabolism are not among the additional benefits of olmesartan that extend beyond blood pressure reduction.

The resist diabetes trial: Rationale, design, and methods of a hybrid efficacy/effectiveness intervention trial for resistance training maintenance to improve glucose homeostasis in older prediabetic adults.

Advancing age is associated with reduced levels of physical activity, increased body weight and fat, decreased lean body mass, and a high prevalence of type 2 diabetes (T2D). Resistance training (RT) increases muscle strength and lean body mass, and reduces risk of T2D among older adults. The Resist Diabetes trial will determine if a social cognitive theory (SCT)-based intervention improves RT maintenance in older, prediabetic adults, using a hybrid efficacy/effectiveness approach. Sedentary, overweight/obese (BMI: 25-39.9 kg/m(2)) adults aged 50-69 (N = 170) with prediabetes (impaired fasting glucose and/or impaired glucose tolerance) completed a supervised 3-month RT (2×/wk) initiation phase and were then randomly assigned (N = 159; 94% retention) to one of two 6-month maintenance conditions: SCT or standard care. The SCT intervention consisted of faded contacts compared to standard care. Participants continue RT at an approved, self-selected community facility during maintenance. A subsequent 6-month period involves no contact for both conditions. Assessments occur at baseline and months 3 (post-initiation), 9 (post-intervention), and 15 (six months after no contact). Primary outcomes are prediabetes indices (i.e., impaired fasting and 2-hour glucose concentration) and strength. Secondary measures include insulin sensitivity, beta-cell responsiveness, and disposition index (oral glucose and C-peptide minimal model); adherence; body composition; and SCT measures. Resist Diabetes is the first trial to examine the effectiveness of a high fidelity SCT-based intervention for maintaining RT in older adults with prediabetes to improve glucose homeostasis. Successful application of SCT constructs for RT maintenance may support translation of our RT program for diabetes prevention into community settings.

Using response variation to develop more effective, personalized behavioral medicine?: evidence from the Resist Diabetes study.

Health behavior interventions have achieved some notable outcomes through generally higher dose interventions with intensive initial phases and long-term, faded contact maintenance phases with attention to mean changes and adherence rates. Interventions may be improved by shifting attention to the very large response variation that is typical for such protocols as exercise with non-, low, moderate, and high responders and even those who show adverse responses. Data from the Resist Diabetes study, which included adults (N = 159, ages 50-69 years) with prediabetes who were overweight or obese (BMI 25-39.9 kg/m(2)) and previously inactive, are presented. The data show a typical pattern of wide variation for changes on a 2-h oral glucose tolerance test (OGTT), defined by blood glucose concentration measured after 2 h following ingestion of 75 g of glucose, lean body mass, fat mass, strength, and blood pressure to the same resistance training protocol within a highly supervised phase and where adherence was high. A personalized behavioral medicine approach could focus on such individual patterns of response variation to tailor and alter additional intervention components, the staging of maintenance interventions, and then determining how to most effectively, and systematically, translate this adaptive intervention approach into practice to potentially achieve more optimal clinical outcomes.

Dietary intake modification in response to a participation in a resistance training program for sedentary older adults with prediabetes: findings from the Resist Diabetes study.

Engagement in one type of health behavior change may exert a "spillover" effect resulting in other behavior changes. Few studies have examined dietary intake following prolonged training, and none have evaluated spontaneous dietary changes beyond alterations in energy or macronutrient intake following initiation of strength/resistance training (RT). The purpose of this observational investigation was to determine if spontaneous dietary intake modifications occur in response to initiation of an RT program, among older adults. Previously sedentary adults with prediabetes (n=134, age=59±1 years) were enrolled in a supervised 12-week RT program. Participants were not given dietary advice or encouraged to change eating behaviors. Three non-consecutive 24-hour dietary recalls were collected at baseline and after 12 weeks of RT. Reductions in intake of energy (1914±40 kcal vs. 1834±427 kcal, p=0.010), carbohydrate (211.6±4.9 g vs. 201.7±5.2 g, p=0.015), total sugar (87.4±2.7 g vs. 81.5±3.1 g, p=0.030), glycemic load (113.4±3.0 vs. 108.1±3.2, p=0.031), fruits and vegetables (4.6±0.2 servings vs. 4.1±0.2 servings, p=0.018), and sweets and desserts (1.1±0.07 servings vs. 0.89±0.07 servings, p=0.023) were detected over time. No changes in other dietary intake variables were observed. Mode of exercise and disease state may be important factors in determining whether dietary modifications occur with exercise initiation, among previously sedentary adults. Successful initiation of RT may represent an opportunity for health care professionals to promote beneficial changes in dietary habits, among older adults with prediabetes.

Angiotensin II receptor blockade and insulin sensitivity in overweight and obese adults with elevated blood pressure.

We tested the hypothesis that olmesartan, an angiotensin II receptor blocker (ARB) devoid of peroxisome proliferator-activated receptor γ agonist activity, would improve whole-body insulin sensitivity in overweight and obese individuals with elevated blood pressure (BP). Sixteen individuals (8 women, 8 men; age=49.5 ± 2.9 years; body mass index=33.0 ± 1.7 kg/m2) were randomly assigned in a crossover manner to control and ARB interventions. Insulin sensitivity was determined from intravenous glucose tolerances tests before and after each 8-week intervention. BP, body weight, body fat, lipid and lipoprotein concentrations, and insulin sensitivity were similar at baseline for both treatments (all p > 0.05). Diastolic BP and triglyceride concentrations were higher (p = 0.007 and 0.042 respectively) at baseline for the ARB compared with the control intervention. Systolic (-11.7 mmHg; p = 0.008) and diastolic (-12.1 mmHg; p = 0.0001) BP decreased, however insulin sensitivity did not change (p > 0.05) following ARB treatment. Furthermore, there were no significant correlates of changes in insulin sensitivity following the ARB intervention. In summary, our findings indicate that short-term ARB treatment did not affect whole-body insulin sensitivity in overweight or obese individuals with elevated BP. Future studies are needed to clarify the effect of individual ARBs on insulin sensitivity in obesity.

Arterial destiffening with weight loss in overweight and obese middle-aged and older adults.

We tested the hypothesis that weight loss via a hypocaloric diet would reduce arterial stiffness in overweight and obese middle-aged and older adults. Thirty-six individuals were randomly assigned to a weight loss (n=25; age: 61.2+/-0.8 years; body mass index: 30.0+/-0.6 kg/m(2)) or a control (n=11; age: 66.1+/-1.9 years; body mass index: 31.8+/-1.4 kg/m(2)) group. Arterial stiffness was measured via carotid artery ultrasonography combined with applanation tonometry and carotid-femoral pulse wave velocity via applanation tonometry at baseline and after the 12-week intervention. Body weight, body fat, abdominal adiposity, blood pressure, beta-stiffness index, and carotid-femoral pulse wave velocity were similar in the 2 groups at baseline (all P>0.05). Body weight (-7.1+/-0.7 versus -0.7+/-1.1 kg), body fat, and abdominal adiposity decreased in the weight loss group but not in the control group (all P<0.05). Brachial systolic and diastolic blood pressures declined (P<0.05) only in the weight loss group. Central systolic and pulse pressures did not change significantly in either group. beta-Stiffness index (-1.24+/-0.22 versus 0.52+/-0.37 U) and carotid-femoral pulse wave velocity (-187+/-29 versus 15+/-42 cm/s) decreased in the weight loss group but not in the control group (all P<0.05). The reductions in carotid-femoral pulse wave velocity were correlated with reductions in total body and abdominal adiposity (r=0.357-0.602; all P<0.05). However, neither total body nor abdominal adiposity independently predicted reductions in arterial stiffness indices. In summary, our findings indicate that weight loss reduces arterial stiffness in overweight/obese middle-aged and older adults, and the magnitudes of these improvements are related to the loss of total and abdominal adiposity.

Leptin, blood pressure, and aerobic capacity in women.

BACKGROUND: In animals, the adipocyte-derived hormone leptin induces increased blood pressure centrally via the hypothalamus, and one study has reported that exercise training decreases hypothalamic leptin receptor expression. In humans, high circulating leptin concentrations are associated with high blood pressure, but the possible influence of physical activity or aerobic capacity on this association is unknown. METHODS: Forty-two healthy women, 25-40 years of age, with diverse ranges of body fatness and aerobic capacities, were studied under basal resting conditions. Blood pressure (sphygmomanometry), arterial stiffness (pulse wave velocity (PWV)), percent body fat (dual energy X-ray absorptiometry), circulating concentrations of leptin, soluble leptin receptor (sLR) (enzyme-linked immunoassay), and nitric oxide (Griess reaction) were measured. RESULTS: Serum leptin correlated with percent body fat (R(2) = 0.74, P < 0.0001) but was not significantly associated with aerobic capacity. Blood pressure correlated positively with serum leptin concentrations and had a negative interaction with aerobic capacity for both systolic (overall model: R(2) = 0.33, P = 0.002) and diastolic (R(2) = 0.48, P < 0.0001) pressure. The relation between leptin and blood pressure was attributable solely to women with below-median aerobic capacity even though their body fat percentages and leptin concentrations were similar to those of women above the median. The results could not be attributed to differences in peripheral factors such as sLR or nitric oxide concentrations or to differences in arterial stiffness determined by aortic PWV. CONCLUSIONS: Circulating leptin concentrations are related to body fatness, but the hypertensive influence of leptin is modified by physical fitness.