Short term aerobic exercise training in young males does not alter sensitivity to a central serotonin agonist

An increase in the concentration of serotonin in the brain has been shown to cause fatigue during exercise in humans and experimental animals. This type of fatigue is referred to as central fatigue and is likely to be mediated by the concentration of serotonin as well as serotonin receptor sensitivity. Serotonin (5-HT) receptor antagonism in humans and experimental animals has been shown to improve endurance performance. A previous report has shown decreased receptor sensitivity in athletes compared to sedentary controls. It is unclear whether this is due to a training adaptation or if individuals are predisposed to enhanced athletic performance due to their inherent decreased receptor sensitivity. The present study investigated changes in 5-HT receptor sensitivity in response to aerobic exercise. Subjects completed 3 × 30 min of stationary cycling at 70% of their peak aerobic power (V̇O2,peak) for 9 weeks. Serotonin receptor sensitivity was assessed indirectly by measuring the neuroendocrine response following administration of a serotonin agonist (buspirone hydrochloride). The neuroendocrine response following administration of a placebo was also investigated in a blind crossover design. A group of sedentary control subjects was also recruited to control for seasonal variations in central receptor sensitivity. The training caused a significant increase in V̇O2,peak (3.1 ± 0.16 to 3.6 ± 0.15 l min−1, P < 0.05) and endurance capacity (93 ± 8 to 168 ± 11 min, P < 0.05), but there was no change (P > 0.05) in the neuroendocrine response in the presence of a serotonin agonist. However, one-quarter of the subjects in the training group demonstrated decreases in receptor sensitivity. These results suggest that despite increases in V̇O2,peak and endurance performance, there was no measurable change in 5-HT receptor sensitivity in the presence of a serotonin agonist. In addition, it is possible that changes in receptor sensitivity may take longer to occur, that the training stimulus used in the present investigation was inadequate and/or that changes occurred in receptor subtypes that were not probed by the agonist used in the present investigation.

Effects of resistance or aerobic exercise training on interleukin-6, C-reactive protein, and body composition

PURPOSE: To determine the effects of 10 wk of resistance or aerobic exercise training on interleukin-6 (IL-6) and C-reactive protein (CRP). Further, to determine pretraining and posttraining associations between alterations of IL-6 and CRP and alterations of total body fat mass (TB-FM), intra-abdominal fat mass (IA-FM), and total body lean mass (TB-LM). METHODS: A sample of 102 sedentary subjects were assigned to a resistance group (n = 35), an aerobic group (n = 41), or a control group (n = 26). Before and after intervention, subjects were involved in dual-energy x-ray absorptiometry, muscular strength and aerobic fitness, measurements and further provided a resting fasted venous blood sample for measures of IL-6, CRP, cholesterol profile, triglycerides, glucose, insulin, and glycosylated hemoglobin. The resistance and the aerobic groups completed a respective 10-wk supervised and periodized training program, whereas the control group maintained sedentary lifestyle and dietary patterns. RESULTS: Both exercise training programs did not reduce IL-6; however, the resistance and the aerobic groups reduced CRP by 32.8% (P < 0.05) and 16.1% (P = 0.06), respectively. At baseline, CRP was positively correlated with IL-6 (r = 0.35), (TB-FM) (r = 0.36), and IA-FM (r = 0.31) and was inversely correlated with aerobic fitness measures (all r values > or = -0.24). Compared with the resistance and the control groups, the aerobic group exhibited significant (P < 0.05) improvements in all aerobic fitness measures and significant reductions in IA-FM (7.4%) and body mass (1.1%). Compared with the aerobic and the control groups, the resistance group significantly (P < 0.05) improved TB-FM (3.7%) and upper (46.3%) and lower (56.6%) body strength. CONCLUSION: Despite no alteration in baseline IL-6 and significantly smaller reductions in measures of adipose tissue as compared with the aerobic training group, only resistance exercise training resulted in significant attenuation of CRP concentration.

Improvements in insulin resistance with exercise training: a lipocentric approach

Traditional views on the metabolic derangements underlying insulin resistance and Type 2 diabetes have been largely “glucocentric” in nature, focusing on the hyperglycemic and/or hyperinsulinemic states that result from impaired glucose tolerance. But in addition to glucose intolerance, there is a coordinated breakdown in lipid dynamics in individuals with insulin resistance, manifested by elevated levels of circulating free fatty acids, diminished rates of lipid oxidation, and excess lipid accumulation in skeletal muscle and/or liver. This review examines the premise that an oversupply and/or accumulation of lipid directly inhibits insulin action on glucose metabolism via changes at the level of substrate competition, enzyme regulation, intracellular signaling, and/or gene transcription. If a breakdown in lipid dynamics is causal in the development of insulin resistance (rather than a coincidental feature resulting from it), it should be possible to demonstrate that interventions that improve lipid homeostasis cause reciprocal changes in insulin sensitivity. Accordingly, the efficacy of aerobic endurance training in human subjects in mediating the association between deranged lipid metabolism and insulin resistance will be examined. It will be demonstrated that aerobic exercise training is a potent and effective primary intervention strategy in the prevention and treatment of individuals with insulin resistance.

Fitness outcomes from a randomised controlled trial of exercise training for men with prostate cancer: the ENGAGE study

Purpose The main purpose of this study was to investigate the effects of a 12-week, clinician-referred, community-based exercise training program with supervised and unsupervised sessions for men with prostate cancer. The secondary purpose was to determine whether androgen deprivation therapy (ADT) modified responses to exercise training.

Methods Secondary analysis was undertaken on data from a multicentre cluster randomised controlled trial in which 15 clinicians were randomly assigned to refer eligible patients to an exercise training intervention (n = 8) or to provide usual care (n = 7). Data from 119 patients (intervention n = 53, control n = 66) were available for this analysis. Outcome measures included fitness and physical function, anthropometrics, resting heart rate, and blood pressure.

Results Compared to the control condition, men in the intervention significantly improved their 6-min walk distance (Mdiff = 49.98 m, padj = 0.001), leg strength (Mdiff = 21.82 kg, padj = 0.001), chest strength (Mdiff = 6.91 kg, padj = 0.001), 30-s sit-to-stand result (Mdiff = 3.38 reps, padj = 0.001), and reach distance (Mdiff = 4.8 cm, padj = 0.024). A significant difference (unadjusted for multiplicity) in favour of men in the intervention was also found for resting heart rate (Mdiff = −3.76 beats/min, p = 0.034). ADT did not modify responses to exercise training.

Conclusions Men with prostate cancer who act upon clinician referrals to community-based exercise training programs can improve their strength, physical functioning, and, potentially, cardiovascular health, irrespective of whether or not they are treated with ADT.

Implications for Cancer Survivors Clinicians should inform men with prostate cancer about the benefits of exercise and refer them to appropriately qualified exercise practitioners and suitable community-based programs.

Aerobic exercise and resistance training for the management of type 2 diabetes mellitus

BACKGROUND
Implementation of a structured physical exercise program can improve glycemic control in patients with type 2 diabetes mellitus.

OBJECTIVE
To evaluate the efficacy of aerobic exercise and resistance training (either alone or in combination) in the management of type 2 diabetes mellitus.

DESIGN AND INTERVENTION
DARE (Diabetes Aerobic and Resistance Exercise) was a 26-week, single-center, parallel-group, randomized, controlled trial of patients with type 2 diabetes mellitus of >6 months' duration. Participants were aged 39-70 years with a baseline [HbA.sub.1c] level 6.6-9.9%. Exclusion criteria included current insulin therapy, regular exercise regime and blood pressure >160/95 mmHg. All participants underwent a 4-week run-in period that comprised 12 sessions of combined aerobic exercise and resistance training; participants who attended [greater than or equal to] 10 sessions were eligible to enter the study. Eligible participants were randomly allocated to one of four groups: aerobic exercise alone; resistance training alone; combined aerobic exercise and resistance training; and no intervention (control group). Exercise was performed three times weekly. The aerobic exercise group progressed from 15-20 min on a treadmill or bicycle ergometer per session at 60% of the maximum heart rate to 45 min per session at 75% of the maximum heart rate. The resistance training group performed 7 different exercises on weight machines per 45 min session, and progressed to 2-3 sets of each exercise at the maximum weight that could be lifted 7-9 times. The combined exercise group performed the full aerobic exercise program plus the full resistance training program. Participants in the control group reverted to their pre-study exercise levels.

OUTCOME MEASURES
The primary outcome measure was the change in [HbA.sub.1c] from baseline. Secondary outcome measures included changes in blood pressure, lipid profile, and body composition.

RESULTS
A total of 251 participants were eligible for intervention. The median session attendance was 80% (aerobic exercise), 85% (resistance training) and 86% (combined exercise). When compared with the control group, the HbA1c levels were reduced by 0.50% in the aerobic exercise group (P = 0.007) and by 0.38% in the resistance training group (P = 0.038). The combined exercise group had an additional reduction of 0.46% when compared with the aerobic exercise group (P = 0.014) and of 0.59% when compared with the resistance training group (P = 0.001). Decreases in [HbA.sub.1c] levels were greatest for participants with a baseline [HbA.sub.1c] level = 7.5% (P <0.001). For participants with a baseline level [HbA.sub.1c] <7.5%, significant improvements in glycemic control were observed in the combined exercise group only (P = 0.002). Changes in blood pressure and lipid profiles did not differ between the groups. By contrast, participation in a structured exercise program improved body composition.

CONCLUSION
Although aerobic exercise or resistance training alone improved glycemic control, additional improvements were observed with the combined exercise regimen.

Exercise and Sports Science Australia position statement on exercise training and chronic heart failure

Chronic heart failure (CHF) is a complex syndrome characterised by progressive decline in left ventricular function, low exercise tolerance and raised mortality and morbidity. Regular exercise participation has been shown to be a safe and effective treatment modality in the majority of CHF patients, partially reversing some of the maladaptations evident in myocardial and skeletal muscle function, and resulting in improvements in physical fitness and quality of life, and perhaps reduced mortality. The volume and intensity of exercise that is recommended depends on the syndrome severity, however in most patients it should consist of a combination of low-to-moderate intensity aerobic (endurance) exercise on most days of the week and individually prescribed low-to-moderate intensity resistance (strength) training at least twice per week. Additionally, all patients should be closely monitored prior to and during exercise for contraindications by an appropriately trained health professional. The purpose of this statement is to inform and guide exercise practitioners and health professionals in the safe and effective prescription and supervision of exercise for patients with CHF.

Exercise training during energy restriction in clinically severe obesity

 In women with clinically severe obesity, 250 minutes of moderate to vigorous intensity aerobic and resistance exercise training combined with energy restriction facilitated fat mass loss and protected against lean mass loss. Additionally, exercise training resulted in clinically meaningful improvements in fitness, physical function, and markers of cardiometabolic disease.

Effect of exercise training on left ventricular remodeling in diabetic patients with diastolic dysfunction: rationale and design

This study will examine the effects of combined aerobic and resistance training on left ventricular remodeling in diabetic patients with diastolic dysfunction. This is the first randomized controlled trial to look for effects of combined strength training and aerobic exercise on myocardial function as well as other clinical, functional, or psychological parameters in diabetic patients with isolated diastolic dysfunction, and will provide important insights into the potential management strategies for heart failure with preserved ejection fraction.

The functional and clinical outcomes of exercise training following a very low energy diet for severely obese women: study protocol for a randomised controlled trial

BACKGROUND: Clinical practice guidelines globally recommend lifestyle modification including diet and exercise training as first-line treatment for obesity. The clinical benefits of exercise training in adults with obesity is well-documented; however, there is no strong evidence for the effectiveness of exercise training for weight loss in class II and class III obesity. The purpose of the randomised controlled trial described in this protocol article is to examine the effect of exercise training, in addition to a very low energy diet (VLED), in clinically severe obese women for changes in body composition, physical function, quality of life, and markers of cardiometabolic risk.

METHODS/DESIGN: Sixty women, aged 18-50 years with a body mass index (BMI) greater than 34.9 kg.m(2) and at least one obesity-related co-morbidity, will be recruited for this 12-month study. Participants will be randomised to either exercise plus energy restriction (n = 30), or energy restriction alone (n = 30). All participants will follow an energy-restricted individualised diet incorporating a VLED component. The exercise intervention group will also receive exercise by supervised aerobic and resistance training and a home-based exercise programme totalling 300 minutes per week. Primary outcome measures include body composition and aerobic fitness. Secondary outcome measures include: physical function, cardiometabolic risk factors, quality of life, physical activity, and mental health. All outcome measures will be conducted at baseline, 3, 6 and 12 months.

DISCUSSION: Previous research demonstrates various health benefits of including exercise training as part of a healthy lifestyle at all BMI ranges. Although clinical practice guidelines recommend exercise training as part of first-line treatment for overweight and obesity, there are few studies that demonstrate the effectiveness of exercise in class II and class III obesity. The study aims to determine whether the addition of exercise training to a VLED provides more favourable improvements in body composition, physical function, quality of life, and markers of cardiometabolic risk for women with clinically severe obesity, compared to VLED alone.

Exercise training increases lipid metabolism gene expression in human skeletal muscle

The effects of a single bout of exercise and exercise training on the expression of genes necessary for the transport and beta -oxidation of fatty acids (FA), together with the gene expression of transcription factors implicated in the regulation of FA homeostasis were investigated. Seven human subjects (3 male, 4 female, 28.9 ± 3.1 yr of age, range 20-42 yr, body mass index 22.6 kg/m², range 17-26 kg/m²) underwent a 9-day exercise training program of 60 min cycling per day at 63% peak oxygen uptake (V_{O2 peak}; 104 ± 14 W). On days 1 and 9 of the program, muscle biopsies were sampled from the vastus lateralis muscle at rest, at the completion of exercise, and again 3 h postexercise. Gene expression of key components of FA transport [FA translocase (FAT/CD36), plasma membrane-associated FA-binding protein], beta -oxidation [carntine palmitoyltransferase(CPT) I, beta -hydroxyacyl-CoA dehydrogenase] and transcriptional control [peroxisome proliferator-activated receptor (PPAR)alpha , PPARgamma , PPARgamma coactivator 1, sterol regulatory element-binding protein-1c] were unaltered by exercise when measured at the completion and at 3 h postexercise. Training increased total lipid oxidation by 24% (P < 0.05) for the 1-h cycling bout. This increased capacity for lipid oxidation was accompanied by an increased expression of FAT/CD36 and CPT I mRNA. Similarly, FAT/CD36 protein abundance was also upregulated by exercise training. We conclude that enhanced fat oxidation after exercise training is most closely associated with the genes involved in regulating FA uptake across the plasma membrane (FAT/CD36) and across the mitochondrial membrane (CPT I).

Improved endothelial function following a 14 month resistance exercise training program in adults with type 2 diabetes

Objective
We examined the effect of a 14-month progressive resistance training (PRT) program on endothelial function in both a supervised training (Center) group and non-supervised training (Home) group of patients with type 2 diabetes. We studied 28 men and women with type 2 diabetes who participated in a 14-month PRT involving an initial 2-month supervised program and a 12-month maintenance program.

Methods
Endothelial function testing was performed through laser doppler flow responses in the skin microcirculation to iontophoresis of acetylcholine (ACh) and sodium nitroprusside (NaNP) and doses of 4, 8 and 16 mC were used. Measurements of vascular response (VR), HbA1c, weight and blood pressure were performed at 0, 2 and 14 months.

Results
VR to ACh and NaNP was significantly increased at 14 months compared with baseline in both the Center and Home groups. However, no between-group differences were observed. A significant correlation was observed between HbA1c and VR to ACh at baseline and 8 weeks using 8 mC dose of ACh. There was a strong correlation between HbA1c at baseline and VR at 14 months using all three doses of ACh (4 mC:r = −0.546, p = 0.003, 8 mC:r = −0.470, p = 0.002, 16 mC:r = −0.547, p = 0.006).

Conclusions/interpretation
Endothelial function is improved following 14 months of PRT in type 2 diabetes both in a supervised and non-supervised program. Strong correlations with HbA1c including initial HbA1c levels suggest that glycemic control may be an important factor in long-term regulation of endothelial function.

Moderate-intensity resistance exercise training in patients with chronic heart failure improves strength, endurance, heart rate variability, and forearm blood flow

Thirty-nine CHF patients (New York Heart Association Functional Class = 2.3±0.5; left ventricular ejection fraction 28%±7%; age 65±11 years; 33:6 male:female) underwent 2 identical series of tests, 1 week apart, for strength and endurance of the knee and elbow extensors and flexors, VO_2peak, HRV, FBF at rest, and FBF activated by forearm exercise or limb ischemia. Patients were then randomized to 3 months of resistance training (EX, n = 19), consisting of mainly isokinetic (hydraulic) ergometry, interspersed with rest intervals, or continuance with usual care (CON, n = 20), after which they underwent repeat endpoint testing. Combining all 4 movement patterns, strength increased for EX by 21±30% (mean±SD, P<.01) after training, whereas endurance improved 21±21% (P<.01). Corresponding data for CON remained almost unchanged (strength P<.005, endurance P<.003 EX versus CON). VO_2peak improved in EX by 11±15% (P<.01), whereas it decreased by 10±18% (P<.05) in CON (P<.001 EX versus CON). The ratio of low-frequency to high-frequency spectral power fell after resistance training in EX by 44±53% (P<.01), but was unchanged in CON (P<.05 EX versus CON). FBF increased at rest by 20±32% (P<.01), and when stimulated by submaximal exercise (24±32%, P<.01) or limb ischemia (26±45%, P<.01) in EX, but not in CON (P<.01 EX versus CON).