Recent guidelines on exercise for weight loss and weight maintenance include resistance training as part of the exercise prescription. Yet few studies have compared the effects of similar amounts of ...aerobic and resistance training on body mass and fat mass in overweight adults. STRRIDE AT/RT, a randomized trial, compared aerobic training, resistance training, and a combination of the two to determine the optimal mode of exercise for obesity reduction. Participants were 119 sedentary, overweight or obese adults who were randomized to one of three 8-mo exercise protocols: 1) RT: resistance training, 2) AT: aerobic training, and 3) AT/RT: aerobic and resistance training (combination of AT and RT). Primary outcomes included total body mass, fat mass, and lean body mass. The AT and AT/RT groups reduced total body mass and fat mass more than RT (P < 0.05), but they were not different from each other. RT and AT/RT increased lean body mass more than AT (P < 0.05). While requiring double the time commitment, a program of combined AT and RT did not result in significantly more fat mass or body mass reductions over AT alone. Balancing time commitments against health benefits, it appears that AT is the optimal mode of exercise for reducing fat mass and body mass, while a program including RT is needed for increasing lean mass in middle-aged, overweight/obese individuals.
Aerobic training (AT) improves the metabolic syndrome (MS) and its component risk factors; however, to our knowledge, no randomized clinical studies have addressed whether resistance training (RT) ...improves the MS when performed alone or combined with AT. Sedentary, overweight dyslipidemic men and women, aged 18 to 70 years completed a 4-month inactive run-in period and were randomized to 1 of 3 eight-month exercise programs (n = 196). The exercise programs were (1) RT (3 days/week, 3 sets/day of 8 to 12 repetitions of 8 different exercises targeting all major muscle groups); (2) AT (∼120 minutes/week at 75% of the maximum oxygen uptake), and (3) AT and RT combined (AT/RT) (exact combination of AT and RT). Of the 196 randomized patients, 144 completed 1 of the 3 exercise programs. The 86 participants with complete data for all 5 MS criteria were used in the present analysis, and a continuous MS z score was calculated. Eight months of RT did not change the MS score. AT improved the MS score (p <0.07) and showed a trend toward significance compared to RT (p <0.10). AT/RT significantly decreased the MS score and was significantly different from RT alone. In conclusion, RT was not effective at improving the MS score; however, AT was effective. Combined AT and RT was similarly effective but not different from AT alone. When weighing the time commitment versus health benefit, the data suggest that AT alone was the most efficient mode of exercise for improving cardiometabolic health.
Site-based cardiac rehabilitation (CR) provides supervised exercise, education and motivation for patients. Graduates of CR have improved exercise tolerance. However, when participation in CR ceases, ...adherence to regular physical activity often declines, consequently leading to worsening risk factors and clinical events. Therefore, the purpose of this pilot study was to evaluate if a mHealth program could sustain the fitness and physical activity levels gained during CR.
A 12-week mHealth program was implemented using physical activity trackers and health coaching. Twenty-five patients were randomized into mHealth or usual care after completing CR. The combination of a 4.7±13.8% increase in the mHealth and a 8.5±11.5% decrease in the usual care group resulted in a difference between groups (P≤.05) for absolute peak VO2. Usual care decreased the amount of moderate-low physical activity minutes per week (117±78 vs 50±53; P<.05) as well as moderate-high (111±87 vs 65±64; P<.05). mHealth increased moderate-high physical activity (138±113 vs 159±156; NS). The divergent changes between mHealth and usual care in moderate-high physical activity minutes/week resulted in a difference between groups (21±103 vs – 46±36; P<.05).
A 12-week mHealth program of physical activity trackers and health coaching following CR graduation can sustain the gains in peak VO2 and physical activity achieved by site-based CR.
Aims/hypotheses
Obesity is associated with decreased insulin sensitivity (IS) and elevated plasma branched-chain amino acids (BCAAs). The purpose of this study was to investigate the relationship ...between BCAA metabolism and IS in overweight (OW) individuals during exercise intervention.
Methods
Whole-body leucine turnover, IS by hyperinsulinaemic–euglycaemic clamp, and circulating and skeletal muscle amino acids, branched-chain α-keto acids and acylcarnitines were measured in ten healthy controls (Control) and nine OW, untrained, insulin-resistant individuals (OW-Untrained). OW-Untrained then underwent a 6 month aerobic and resistance exercise programme and repeated testing (OW-Trained).
Results
IS was higher in Control vs OW-Untrained and increased significantly following exercise. IS was lower in OW-Trained vs Control expressed relative to body mass, but was not different from Control when normalised to fat-free mass (FFM). Plasma BCAAs and leucine turnover (relative to FFM) were higher in OW-Untrained vs Control, but did not change on average with exercise. Despite this, within individuals, the decrease in molar sum of circulating BCAAs was the best metabolic predictor of improvement in IS. Circulating glycine levels were higher in Control and OW-Trained vs OW-Untrained, and urinary metabolic profiling suggests that exercise induces more efficient elimination of excess acyl groups derived from BCAA and aromatic amino acid (AA) metabolism via formation of urinary glycine adducts.
Conclusions/interpretation
A mechanism involving more efficient elimination of excess acyl groups derived from BCAA and aromatic AA metabolism via glycine conjugation in the liver, rather than increased BCAA disposal through oxidation and turnover, may mediate interactions between exercise, BCAA metabolism and IS.
Trial registration:
Clinicaltrials.gov NCT01786941
While the benefits of exercise are clear, many unresolved issues surround the optimal exercise prescription. Many organizations recommend aerobic training (AT) and resistance training (RT), yet few ...studies have compared their effects alone or in combination. The purpose of this study, part of Studies Targeting Risk Reduction Interventions Through Defined Exercise-Aerobic Training and/or Resistance Training (STRRIDE/AT/RT), was to compare the effects of AT, RT, and the full combination (AT/RT) on central ectopic fat, liver enzymes, and fasting insulin resistance homeostatic model assessment (HOMA). In a randomized trial, 249 subjects 18-70 yr old, overweight, sedentary, with moderate dyslipidemia (LDL cholesterol 130-190 mg/dl or HDL cholesterol ≤ 40 mg/dl for men or ≤ 45 mg/dl for women) performed an initial 4-mo run-in period. Of these, 196 finished the run-in and were randomized into one of the following 8-mo exercise-training groups: 1) RT, which comprised 3 days/wk, 8 exercises, 3 sets/exercise, 8-12 repetitions/set, 2) AT, which was equivalent to ∼19.2 km/wk (12 miles/wk) at 75% peak O(2) uptake, and 3) full AT + full RT (AT/RT), with 155 subjects completing the intervention. The primary outcome variables were as follows: visceral and liver fat via CT, plasma liver enzymes, and HOMA. AT led to significant reductions in liver fat, visceral fat, alanine aminotransferase, HOMA, and total and subcutaneous abdominal fat (all P < 0.05). RT resulted in a decrease in subcutaneous abdominal fat (P < 0.05) but did not significantly improve the other variables. AT was more effective than RT at improving visceral fat, liver-to-spleen ratio, and total abdominal fat (all P < 0.05) and trended toward a greater reduction in liver fat score (P < 0.10). The effects of AT/RT were statistically indistinguishable from the effects of AT. These data show that, for overweight and obese individuals who want to reduce measures of visceral fat and fatty liver infiltration and improve HOMA and alanine aminotransferase, a moderate amount of aerobic exercise is the most time-efficient and effective exercise mode.
Aims/hypothesis
Although the Diabetes Prevention Program (DPP) established lifestyle changes (diet, exercise and weight loss) as the ‘gold standard’ preventive therapy for diabetes, the relative ...contribution of exercise alone to the overall utility of the combined diet and exercise effect of DPP is unknown; furthermore, the optimal intensity of exercise for preventing progression to diabetes remains very controversial. To establish clinical efficacy, we undertook a study (2009 to 2013) to determine: how much of the effect on measures of glucose homeostasis of a 6 month programme modelled after the first 6 months of the DPP is due to exercise alone; whether moderate- or vigorous-intensity exercise is better for improving glucose homeostasis; and to what extent amount of exercise is a contributor to improving glucose control. The primary outcome was improvement in fasting plasma glucose, with improvement in plasma glucose AUC response to an OGTT as the major secondary outcome.
Methods
The trial was a parallel clinical trial. Sedentary, non-smokers who were 45–75 year old adults (
n
= 237) with elevated fasting glucose (5.28–6.94 mmol/l) but without cardiovascular disease, uncontrolled hypertension, or diabetes, from the Durham area, were studied at Duke University. They were randomised into one of four 6 month interventions: (1) low amount (42 kJ kg body weight
−1
week
−1
KKW)/moderate intensity: equivalent of expending 42 KKW (e.g. walking ∼16 km 8.6 miles per week) with moderate-intensity (50%
V
.
O
2
reserve
) exercise; (2) high amount (67 KKW)/moderate intensity: equivalent of expending 67 KKW (∼22.3 km 13.8 miles per week) with moderate-intensity exercise; (3) high amount (67 KKW)/vigorous intensity: equivalent to group 2, but with vigorous-intensity exercise (75%
V
.
O
2
reserve
); and (4) diet + 42 KKW moderate intensity: same as group 1 but with diet and weight loss (7%) to mimic the first 6 months of the DPP. Computer-generated randomisation lists were provided by our statistician (G. P. Samsa). The randomisation list was maintained by L. H. Willis and C. A. Slentz with no knowledge of or input into the scheduling, whereas all scheduling was done by L. A. Bateman, with no knowledge of the randomisation list. Subjects were automatically assigned to the next group listed on the randomisation sheet (with no ability to manipulate the list order) on the day that they came in for the OGTT, by L. H. Willis. All plasma analysis was done blinded by the individuals doing the measurements (i.e. lipids, glucose, insulin). Subjects and research staff (other than individuals analysing the blood) were not blinded to the group assignments.
Results
Number randomised, completers and number analysed with complete OGTT data for each group were: low-amount/moderate-intensity (61, 43, 35); high-amount/moderate-intensity (61, 44, 40); high-amount/vigorous-intensity (61, 43, 38); diet/exercise (54, 45, 37), respectively. Only the diet and exercise group experienced a decrease in fasting glucose (
p
< 0.001). The means and 95% CIs for changes in fasting glucose (mmol/l) for each group were: high-amount/moderate-intensity −0.07 (−0.20, 0.06); high-amount/vigorous 0.06 (−0.07, 0.19); low-amount/moderate 0.05 (−0.05, 0.15); and diet/exercise −0.32 (−0.46, −0.18). The effects sizes for each group (in the same order) were: 0.17, 0.15, 0.18 and 0.71, respecively. For glucose tolerance (glucose AUC of OGTT), similar improvements were observed for the diet and exercise (8.2% improvement, effect size 0.73) and the 67 KKW moderate-intensity exercise (6.4% improvement, effect size 0.60) groups; moderate-intensity exercise was significantly more effective than the same amount of vigorous-intensity exercise (
p
< 0.0207). The equivalent amount of vigorous-intensity exercise alone did not significantly improve glucose tolerance (1.2% improvement, effect size 0.21). Changes in insulin AUC, fasting plasma glucose and insulin did not differ among the exercise groups and were numerically inferior to the diet and exercise group.
Conclusions/interpretation
In the present clinical efficacy trial we found that a high amount of moderate-intensity exercise alone was very effective at improving oral glucose tolerance despite a relatively modest 2 kg change in body fat mass. These data, combined with numerous published observations of the strong independent relation between postprandial glucose concentrations and prediction of future diabetes, suggest that walking ∼18.2 km (22.3 km prescribed with 81.6% adherence in the 67 KKW moderate-intensity group) per week may be nearly as effective as a more intensive multicomponent approach involving diet, exercise and weight loss for preventing the progression to diabetes in prediabetic individuals. These findings have important implications for the choice of clinical intervention to prevent progression to type 2 diabetes for those at high risk.
Trial registration
:
ClinicalTrials.gov NCT00962962
Funding
:
The study was funded by National Institutes for Health National Institute of Diabetes and Digestive and Kidney Diseases (NIH-NDDK) (R01DK081559)
Site-based cardiac rehabilitation (CR) provides supervised exercise, education and motivation for patients. Graduates of CR have improved exercise tolerance. However, when participation in CR ceases, ...adherence to regular physical activity often declines, consequently leading to worsening risk factors and clinical events. Therefore, the purpose of this pilot study was to evaluate if a mHealth program could sustain the fitness and physical activity levels gained during CR.
A 12-week mHealth program was implemented using physical activity trackers and health coaching. Twenty-five patients were randomized into mHealth or usual care after completing CR. The combination of a 4.7±13.8% increase in the mHealth and a 8.5±11.5% decrease in the usual care group resulted in a difference between groups (P≤.05) for absolute peak VO
. Usual care decreased the amount of moderate-low physical activity minutes per week (117±78 vs 50±53; P<.05) as well as moderate-high (111±87 vs 65±64; P<.05). mHealth increased moderate-high physical activity (138±113 vs 159±156; NS). The divergent changes between mHealth and usual care in moderate-high physical activity minutes/week resulted in a difference between groups (21±103 vs - 46±36; P<.05).
A 12-week mHealth program of physical activity trackers and health coaching following CR graduation can sustain the gains in peak VO
and physical activity achieved by site-based CR.
Supervised exercise is beneficial for peripheral artery disease (PAD) patients limited by intermittent claudication (IC). However, supervised exercise for PAD remains widely underutilized. Mobile ...health (mHealth) provides an intermediate solution between supervised and independent home-based exercise. The purpose of this study was to determine the effects on functional capacity and physical activity patterns of a 12-week mHealth program in PAD patients with IC. Twenty patients were randomized into usual care or a 12-week mHealth intervention consisting of patient education, smartphones, and physical activity trackers. Patient education was disseminated through smartphone and a daily exercise prescription was given based on steps per day. Primary outcomes were 12-week changes in peak VO2 and claudication onset time; and changes in physical activity measured by steps per/day and minutes of exercise per/week. mHealth patients significantly increased peak VO2 from 15.2 ± 4.3 to 18.0 ± 4.8 ml/kg/min (20.3 ± 26.4%; p ≤0.05), while usual care did not change from 14.3 ± 5.4 to 14.5 ± 5.7 ml/kg/min (1.0 ± 6.9%; NS). Comparison of these changes resulted in a significant difference between groups (p ≤0.05) for peak VO2. Claudication onset time significantly increased in mHealth (320 ± 226 to 525 ± 252 seconds; ≤ 0.05), while usual care demonstrated a worsening (252 ± 256 to 231 ± 196 seconds; NS). The comparison of these group changes resulted in a significant difference (p ≤0.05). Neither steps per day or minutes of activity reached significant differences between groups. In conclusion, a 12-week mHealth program in PAD patients with IC can improve peak VO2 and claudication onset time; and mHealth interventions represent a promising alternative therapy for those patients who cannot participate in supervised exercise.
Cardiac rehabilitation (CR) is endorsed for coronary artery disease (CAD), but studies report inconsistent findings regarding efficacy. The objective of this study was to determine whether ...confounding factors, potentially contributing to these heterogeneous findings, impact the effect of CR on all-cause readmission and mortality.
Patients (n = 2641) with CAD, CR eligible, and physically able were identified. Electronic medical records were inspected individually for each patient to extract demographic, clinical characteristic, readmission, and mortality information. Patients (n = 214) attended ≥1 CR session (CR group). Survival was considered free from: all-cause readmission; or composite outcome of all-cause readmission or death. Cox proportional hazards models, adjusting for demographics, comorbidities, and discharge criteria, were used to determine HR with 95% CI and to compare 180-d survival rates between the CR and no-CR groups.
During 180 d of follow-up, 12.1% and 18.7% of the CR and non-CR patients were readmitted to the hospital. There was one death (0.5%) in the CR group, while 98 deaths (4.0%) occurred in the non-CR group. After adjustment for age, sex, race, depression, anxiety, dyslipidemia, hypertension, obesity, smoking, type 2 diabetes, and discharge criteria, the final model revealed a significant 42.7% reduction in readmission or mortality risk for patients who attended CR (HR = 0.57: 95% CI, 0.33-0.98; P = .043).
Regardless of demographic characteristics, comorbidities, and cardiovascular discharge criteria, the risk of 180-d all-cause readmission or death was markedly decreased in patients who attended CR compared with those who did not.
Most health organizations recommend a combination of aerobic training (AT) and resistance training (RT), yet few studies have compared their acute (within 24 h of the last exercise bout) and ...sustained (after 14 days of no exercise training) effects alone and in combination on glucose metabolism. The present study (Studies Targeting Risk Reduction Interventions through Defined Exercise-Aerobic Training and/or Resistance Training) compared the effects of AT, RT, and the combination (AT/RT) on insulin action at both acute and sustained phases. Subjects (N = 196) were 18-70 yr old (mean age = 50 yr), overweight (mean body mass index = 30 kg/m2), sedentary with moderate dyslipidemia, and were randomized into one of three 8-mo exercise groups: 1) RT: 3 days/wk, 8 exercises, 3 sets/exercise, 8-12 repetitions/set; 2) AT: equivalent to ∼19.2 km/wk (12 miles/wk) at 75% peak O2 consumption; 3) AT/RT: the combination of AT and RT. One hundred forty-four subjects completed the intervention. Eighty-eight subjects completed all pre- and postintervention testing visits. Insulin sensitivity, glucose effectiveness, and disposition index were measured via a frequently sampled intravenous glucose tolerance test with subsequent minimal model analyses. AT/RT resulted in greater improvements in insulin sensitivity, β-cell function (disposition index), and glucose effectiveness than either AT or RT alone (all P < 0.05). Approximately 52% of the improvement in insulin sensitivity by AT/RT was retained 14 days after the last exercise training bout. Neither AT or RT led to acute or chronic improvement in sensitivity index. In summary, only AT/RT (which required twice as much time as either alone) led to significant acute and sustained benefits in insulin sensitivity
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