The effect of a single 2 h bout of aerobic exercise on ectopic lipids in skeletal muscle,liver and the myocardium

Aims/hypothesis

Ectopic lipids are fuel stores in non-adipose tissues (skeletal muscle [intramyocellular lipids; IMCL], liver [intrahepatocellular lipids; IHCL] and heart [intracardiomyocellular lipids; ICCL]). IMCL can be depleted by physical activity. Preliminary data suggest that aerobic exercise increases IHCL. Data on exercise-induced changes on ICCL is scarce. Increased IMCL and IHCL have been related to insulin resistance in skeletal muscles and liver, whereas this has not been documented in the heart. The aim of this study was to assess the acute effect of aerobic exercise on the flexibility of IMCL, IHCL and ICCL in insulin-sensitive participants in relation to fat availability, insulin sensitivity and exercise capacity.

Methods

Healthy physically active men were included. $ \overset{\cdot }{V}{\mathrm{O}}_{2 \max } $ was assessed by spiroergometry and insulin sensitivity was calculated using the HOMA index. Visceral and subcutaneous fat were separately quantified by MRI. Following a standardised dietary fat load over 3 days, IMCL, IHCL and ICCL were measured using MR spectroscopy before and after a 2 h exercise session at 50–60% of $ \overset{\cdot }{V}{\mathrm{O}}_{2 \max } $ . Metabolites were measured during exercise.

Results

Ten men (age 28.9?±?6.4 years, mean ± SD; $ \overset{\cdot }{V}{\mathrm{O}}_{2 \max } $ 56.3?±?6.4 ml kg^?1 min^?1; BMI 22.75?±?1.4 kg/m²) were recruited. A 2 h exercise session resulted in a significant decrease in IMCL (?17?±?22%, p?=?0.008) and ICCL (?17?±?14%, p?=?0.002) and increase in IHCL (42?±?29%, p?=?0.004). No significant correlations were found between the relative changes in ectopic lipids, fat availability, insulin sensitivity, exercise capacity or changes of metabolites during exercise.

Conclusions/interpretation

In this group, physical exercise decreased ICCL and IMCL but increased IHCL. Fat availability, insulin sensitivity, exercise capacity and metabolites during exercise are not the only factors affecting ectopic lipids during exercise.     

Resistance exercise enhances oxygen uptake without worsening cardiac function in patients with systolic heart failure: a systematic review and meta-analysis

Recent literature suggests that resistance training (RT) improves peak oxygen uptake (\( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak), similarly to aerobic exercise (AE) in patients with heart failure (HF), but its effect on cardiac remodeling is controversial. Thus, we examined the effects of RT and AE on \( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak and cardiac remodeling in patients with heart failure (HF) via a systematic review and meta-analysis. MEDLINE, EMBASE, Cochrane Library and CINAHL, AMEDEO and PEDro databases search were extracted study characteristics, exercise type, and ventricular outcomes. The main outcomes were \( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak (ml kg^?1 min^?1), LVEF (%) and LVEDV (mL). Fifty-nine RCTs were included. RT produced a greater increase in \( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak (3.57 ml kg^?1 min^?1, P < 0.00001, I ² = 0%) compared to AE (2.63 ml kg^?1 min^?1, P < 0.00001, I ² = 58%) while combined RT and AE produced a 2.48 ml kg^?1 min^?1 increase in \( \dot{\mathrm{V}}{\mathrm{O}}_2 \); I ² = 69%) compared to control group. Comparison among the three forms of exercise revealed similar effects on \( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak (P = 0.84 and 1.00, respectively; I ² = 0%). AE was associated with a greater gain in LVEF (3.15%; P < 0.00001, I ² = 17%) compared to RT alone or combined exercise which produced similar gains compared to control groups. Subgroup analysis revealed that AE reduced LVEDV (? 10.21 ml; P = 0.007, I ² = 0%), while RT and combined RT and AE had no effect on LVEDV compared with control participants. RT results in a greater gain in \( \dot{\mathrm{V}}{\mathrm{O}}_2 \) peak, and induces no deleterious effects on cardiac function in HF patients.     

Insulin-mediated suppression of lipolysis in adipose tissue and skeletal muscle of obese type 2 diabetic men and men with normal glucose tolerance

Aims/hypothesis

Impaired regulation of lipolysis and accumulation of lipid intermediates may contribute to obesity-related insulin resistance and type 2 diabetes mellitus. We investigated insulin-mediated suppression of lipolysis in abdominal subcutaneous adipose tissue (AT) and skeletal muscle (SM) of obese men with normal glucose tolerance (NGT) and obese type 2 diabetic men.

Methods

Eleven NGT men and nine long-term diagnosed type 2 diabetic men (7?±?1 years), matched for age (58?±?2 vs 62?±?2 years), BMI (31.4?±?0.6 vs 30.5?±?0.6 kg/m²) and V ? O 2 max $ \overset{\cdot }{V}{\mathrm{O}}_{2 \max } $ (28.9?±?1.5 vs 29.5?±?2.4 ml kg^?1 min^?1) participated in this study. Interstitial glycerol concentrations in AT and SM were assessed using microdialysis during a 1 h basal period and a 6 h stepwise hyperinsulinaemic–euglycaemic clamp (8, 20 and 40 mU m^?2 min^?1). AT and SM biopsies were collected to investigate underlying mechanisms.

Results

Hyperinsulinaemia suppressed interstitial SM glycerol concentrations less in men with type 2 diabetes (?7?±?6%, ?13?±?9% and ?27?±?9%) compared with men with NGT (?21?±?7%, ?38?±?8% and ?53?±?8%) (p?=?0.014). This was accompanied by increased circulating fatty acid and glycerol concentrations, a lower glucose infusion rate (21.8?±?3.1 vs 30.5?±?2.0 μmol kg body weight^?1 min^?1; p?<?0.05), higher hormone-sensitive lipase (HSL) serine 660 phosphorylation, increased saturated diacylglycerol (DAG) lipid species in the muscle membrane and increased protein kinase C (PKC) activation in type 2 diabetic men vs men with NGT. No significant differences in insulin-mediated reduction in AT interstitial glycerol were observed between groups.

Conclusions/interpretation

Our results suggest that a blunted insulin-mediated suppression of SM lipolysis may promote the accumulation of membrane saturated DAG, aggravating insulin resistance, at least partly mediated by PKC. This may represent an important mechanism involved in the progression of insulin resistance towards type 2 diabetes. Trial registration: ClinicalTrials.gov NCT01680133     

The effect of continuous positive airway pressure on total cerebral blood flow in healthy awake volunteers

Purpose

Continuous positive airway pressure (CPAP) is the gold standard treatment for obstructive sleep apnea. However, the physiologic impact of CPAP on cerebral blood flow (CBF) is not well established. Ultrasound can be used to estimate CBF, but there is no widespread accepted protocol. We studied the physiologic influence of CPAP on CBF using a method integrating arterial diameter and flow velocity (FV) measurements obtained for each vessel supplying blood to the brain.

Methods

FV and lumen diameter of the left and right internal carotid, vertebral, and middle cerebral arteries were measured using duplex Doppler ultrasound with and without CPAP at 15 cm H₂O, applied in a random order. Transcutaneous carbon dioxide (PtcCO₂), heart rate (HR), blood pressure (BP), and oxygen saturation were monitored. Results were compared with a theoretical prediction of CBF change based on the effect of partial pressure of carbon dioxide on CBF.

Results

Data were obtained from 23 healthy volunteers (mean?±?SD; 12 male, age 25.1?±?2.6 years, body mass index 21.8?±?2.0 kg/m²). The mean experimental and theoretical CBF decrease under CPAP was 12.5 % (p?<?0.001) and 11.9 % (p?<?0.001), respectively. The difference between experimental and theoretical CBF reduction was not statistically significant (3.84?±?79 ml/min, p?=?0.40). There was a significant reduction in PtcCO₂ with CPAP (p?=?<0.001) and a significant increase in mean BP (p?=?0.0017). No significant change was observed in SaO₂ (p?=?0.21) and HR (p?=?0.62).

Conclusion

Duplex Doppler ultrasound measurements of arterial diameter and FV allow for a noninvasive bedside estimation of CBF. CPAP at 15 cm H₂O significantly decreased CBF in healthy awake volunteers. This effect appeared to be mediated predominately through the hypocapnic vasoconstriction coinciding with PCO₂ level reduction. The results suggest that CPAP should be used cautiously in patients with unstable cerebral hemodynamics.     

Feto-placental vascular dysfunction as a prenatal determinant of adult cardiovascular disease

The objective of the study is to assess the effects of emphysema on peak oxygen uptake ( $ \dot{V}{\text{O}}_{{ 2 {\text{peak}}}} $ ) during a cardiopulmonary exercise test in patients with chronic obstructive pulmonary disease (COPD). We measured $ \dot{V}{\text{O}}_{{ 2 {\text{peak}}}} $ and oxygen pulse in 80 patients with stable COPD exercising maximally. Oxygen saturation was measured by pulse oximetry (SpO₂), and the ventilatory response assessed by the ratio of tidal volume (V _T) at peak to slow vital capacity (SVC) at baseline, and by the percent increase of peak V _T over baseline. Computed tomography imaging (CT scan) served as the reference diagnostic standard for emphysema. Based on the panel-grading (PG) method, emphysema was rated absent or mild (PG ≤ 30, n = 54), or moderate to severe (PG > 30, n = 26). Multiple quantile regression was applied to estimate the effects of PG > 30 on $ \dot{V}{\text{O}}_{{ 2 {\text{peak}}}} $ . At peak exercise, the patients with PG > 30 had significantly lower $ \dot{V}{\text{O}}_{ 2} $ , oxygen pulse and SpO₂, and featured a blunted ventilatory response with respect to those with PG ≤ 30 (p < 0.001). With multiple quantile regression, the effects of PG > 30 on $ \dot{V}{\text{O}}_{{ 2 {\text{Peak}}}} $ were only partially explained by the degree of lung hyperinflation, a substantial component being imputable to impairment of lung diffusing capacity. In conclusion, chronic obstructive pulmonary disease patients with moderate to severe emphysema feature significantly lower exercise tolerance than those with no or mild emphysema. Our findings underscore the need of tailoring therapeutic interventions for COPD to the predominant clinical phenotype to improve exercise capacity.     

Lack of Effect of Nitrates on Exercise Stress Test Results in Patients with Microvascular Angina

Purpose

To assess the effects of short-acting nitrates on exercise stress test (EST) results and the relation between EST results and coronary blood flow (CBF) response to nitrates in patients with microvascular angina (MVA).

Methods

We completed 2 symptom/sign limited ESTs on 2 separate days, in a random sequence and in pharmacological washout, in 29 MVA patients and in 24 patients with obstructive coronary artery disease (CAD): one EST was performed without any intervention (control EST, C-EST), and the other after sublingual isosorbide dinitrate, 5 mg (nitrate EST, N-EST). CBF response to nitroglycerin (25 μg) was assessed in the left anterior descending coronary artery by transthoracic Doppler-echocardiography.

Results

At C-EST. ST-segment depression ≥1 mm (STD) was induced in 26 (90 %) and 23 (96 %) MVA and CAD patients, respectively (p?=?0.42), whereas at N-EST, STD was induced in 25 (86 %) and 14 (56 %) MVA and CAD patients, respectively (p?=?0.01). Time and rate pressure product at 1 mm STD increased during N-EST, compared to C-EST, in CAD patients (475?±?115 vs. 365?±?146 s, p?<?0.001; and 23511?±?4352 vs. 20583?±?6234 bpm?mmHg, respectively, p?=?0.01), but not in MVA patients (308?±?160 vs. 284?±?136 s; p?=?0.19; and 21290?±?5438 vs. 20818?±?4286 bpm?mmHg, respectively, p?=?0.35). In MVA patients, a significant correlation was found between heart rate at STD during N-EST and CBF response to nitroglycerin (r?=?0.40, p?=?0.04).

Conclusions

Short-acting nitrates improve EST results in CAD, but not in MVA patients. In MVA patients a lower nitrate-dependent coronary microvascular dilation may contribute to the lack of effects of nitrates on EST results.     

The acute physiological effects of high- and low-velocity resistance exercise in older adults

The aim of the present study was to determine if workload matched, high-velocity (HVE) and low-velocity (LVE) resistance exercise protocols, elicit differing acute physiological responses in older adults. Ten older adults completed three sets of eight exercises on six separate occasions (three HVE and three LVE sessions). Systolic blood pressure, diastolic blood pressure and blood lactate were measured pre- and post-exercise, heart rate was measured before exercise and following each set of each exercise. Finally, a rating of perceived exertion was measured following each set of each exercise. There were no significant differences in blood lactate (F_(1,9) = 0.028; P = 0.872; \(\eta_{\text{P}}^{ 2}\) = 0.003), heart rate (F_(1,9) = 0.045; P = 0.837; \(\eta_{\text{P}}^{ 2}\) = 0.005), systolic blood pressure (F_(1,9) = 0.023; P = 0.884; \(\eta_{\text{P}}^{ 2}\) = 0.003) or diastolic blood pressure (F_(1,9) = 1.516; P = 0.249; \(\eta_{\text{P}}^{ 2}\) = 0.144) between HVE and LVE. However, LVE elicited significantly greater ratings of perceived exertion compared to HVE (F_(1,9) = 13.059; P = 0.006; \(\eta_{\text{P}}^{ 2}\) = 0.592). The present workload matched HVE and LVE protocols produced comparable physiological responses, although greater exertion was perceived during LVE.     

Preoperative exercise capacity in adult inflammatory bowel disease sufferers, determined by cardiopulmonary exercise testing

Background and aims

Aerobic exercise capacity appears impaired in children with inflammatory bowel disease (IBD). Whether this holds true in adults with IBD is not known. Using cardiopulmonary exercise testing (CPET), we assessed anaerobic threshold (AT) in such patients comparing data with reference values and other elective surgical patients. We also sought to confirm whether the presence of a fistula further reduced AT.

Methods

CPET was performed between November 2007 and December 2010 on patients awaiting abdominopelvic surgery. Gender-specific normal reference values were used for comparison. Unadjusted comparison between two groups was made using Mann–Whitney U test and by unpaired t test. Data were adjusted by analysis of covariance, using age and sex as covariates. Differences between patients’ observed values and reference values were tested using paired t tests.

Results

Four hundred and fourteen patients (234 male) were studied (mean?±?SD age, 56.6?±?16.4?years; weight, 74.2?±?15.6?kg). Adjusted AT values in Crohn’s disease (CD) were lower than colorectal cancer (11.4?±?3.4 vs 13.2?±?3.5?ml.kg^?1.min^?1, p?=?0.03) and for all other colorectal disease groups combined (12.6?±?3.5?ml.kg^?1.min^?1, p?=?0.03). AT of Ulcerative colitis (UC) and CD patients together were reduced compared to population reference values (p?<?0.05).

Conclusion

After adjusting for age and sex, CD patients had a reduced AT compared to patients with colorectal cancer and other colorectal disease groups combined. The pathogenesis of this low AT remains to be defined and warrants further investigation.     

Limitations to exercise in female centenarians: evidence that muscular efficiency tempers the impact of failing lungs

Centenarians are an outstanding model of successful aging, with genetics and healthy lifestyle certainly being key factors responsible for their longevity. Exercise capacity has been identified to play an important role in healthy aging, but a comprehensive assessment of the limitations to maximal exercise in this population is lacking. Following, health histories, lung function, and anthropometric measures, eight female centenarians (98–102 years old) and eight young females (18–22 years old) performed a series of graded maximal exercise tests on a cycle ergometer that facilitated absolute and relative work rate comparisons. Centenarians revealed a dramatically attenuated lung function, as measured by spirometry (forced expiratory volume in 1 s (FEV₁/forced vital capacity (FVC), 55?±?10%) compared to the young (FEV₁/FVC, 77?±?5%). During exercise, although the centenarians relied heavily on respiratory rate which yielded ～50% higher dead space/tidal volume, minute ventilation was similar to that of the young at all but maximal exercise, and alveolar PO₂ was maintained in both groups. In contrast, peak WR and VO₂ were significantly reduced in the centenarians (33?±?4 vs 179?±?24 W; 7.5?±?1.2 vs 39.6?±?3.5 ml min^?1 kg^?1). Arterial PO₂ of the centenarians fell steadily from the normal range of both groups to yield a large A-a gradient (57?±?6 mmHg). Metabolic cost of a given absolute work rate was consistently lower, ～46% less than the young at maximal effort. Centenarians have significant limitations to gas exchange across the lungs during exercise, but this limited oxygen transport is tempered by improved skeletal muscle mechanical efficiency that may play a vital role in maintaining physical function and therefore longevity in this population.     

Clinical characteristics and lung function in chronic obstructive pulmonary disease complicated with impaired peripheral oxygenation

During exercise testing, patients with chronic obstructive pulmonary disease (COPD) often present with ventilatory limitations and various combinations of impaired peripheral oxygenation (IPO) to the exercising muscles. The entities of IPO include anemia, circulation impairment and deconditioning. COPD-IPO is not widely accepted as being a subgroup of COPD. Therefore, the aim of this study was to evaluate the clinical features of COPD-IPO patients. Forty-seven COPD patients underwent cardiopulmonary exercise testing. COPD-IPO was identified when all IPO variables had abnormal values. The patients who did not meet the COPD-IPO criteria were defined as the NIPO group. The variables with abnormal values included peak oxygen uptake ( \( {\dot{\text{V}}\text{O}}_{ 2} \) ) <85 % predicated, anaerobic threshold <40 % \( {\dot{\text{V}}\text{O}}_{{ 2 {\text{max}}}} \) pred, \( {\dot{\text{V}}\text{O}}_{ 2} \) -work rate slope <8.6 ml/watt, oxygen pulse <80 %pred, and ventilatory equivalents for O₂ and CO₂ at nadir (>31 and >34, respectively). Anthropometrics, biochemistry, and lung function were compared between the groups. Forty-six COPD patients were enrolled after excluding one patient who had technical difficulties in performing the exercise tests. Despite FEV₁ and FVC being similarly reduced (p = NS) between the groups, the COPD-IPO (n = 13, 28 %) patients had lower body mass index and were taller, and had impaired diffusing capacity and larger total lung capacity and air-trapping (all p < 0.05). We concluded that COPD patients with all six variables having abnormal values are a unique subgroup and that identification of these patients is worthwhile for further investigations and management such as exercise training and nutritional supplements.     

Agreement between cystatin-C and creatinine based eGFR estimates after a 12-month exercise intervention in patients with chronic kidney disease

Background

Estimation of GFR (eGFR) using formulae based on serum creatinine concentrations are commonly used to assess kidney function. Physical exercise can increase creatinine turnover and lean mass; therefore, this method may not be suitable for use in exercising individuals. Cystatin-C based eGFR formulae may be a more accurate measure of kidney function when examining the impact of exercise on kidney function. The aim of this study was to assess the agreement of four creatinine and cystatin-C based estimates of GFR before and after a 12-month exercise intervention.

Methods

One hundred forty-two participants with stage 3–4 chronic kidney disease (CKD) (eGFR 25–60?mL/min/1.73?m²) were included. Subjects were randomised to either a Control group (standard nephrological care [n?=?68]) or a Lifestyle Intervention group (12?months of primarily aerobic based exercise training [n?=?74]). Four eGFR formulae were compared at baseline and after 12?months: 1) MDRDcr, 2) CKD-EPIcr, 3) CKD-EPIcys and 4) CKD-EPIcr-cys.

Results

Control participants were aged 63.5[9.4] years, 60.3% were male, 42.2% had diabetes, and had an eGFR of 40.5?±?8.9?ml/min/1.73m². Lifestyle Intervention participants were aged 60.5[14.2] years, 59.5% were male, 43.8% had diabetes, and had an eGFR of 38.9?±?8.5?ml/min/1.73m². There were no significant baseline differences between the two groups. Lean mass (r?=?0.319, p?<?0.01) and grip strength (r?=?0.391, p?<?0.001) were associated with serum creatinine at baseline. However, there were no significant correlations between cystatin-C and the same measures. The Lifestyle Intervention resulted in significant improvements in exercise capacity (+?1.9?±?1.8 METs, p?<?0.001). There were no changes in lean mass in both Control and Lifestyle Intervention groups during the 12?months. CKD-EPIcys was considerably lower in both groups at both baseline and 12?months than CKD-EPIcr (Control?=???10.5?±?9.1 and???13.1?±?11.8, and Lifestyle Intervention?=???7.9?±?8.6 and???8.4?±?12.3?ml/min/1.73?m²), CKD-EPIcr-cys (Control?=???3.6?±?3.7 and???4.5?±?4.5, and Lifestyle Intervention?=???3.6?±?3.7 and???2.5?±?5.5?ml/min/1.73?m²) and MDRDcr (Control?=???9.3?±?8.4 and???12.0?±?10.7, Lifestyle Intervention?=???6.4?±?8.4 and???6.9?±?11.2?ml/min/1.73?m²).

Conclusions

In CKD patients participating in a primarily aerobic based exercise training, without improvements in lean mass, cystatin-C and creatinine based eGFR provided similar estimates of kidney function at both baseline and after 12?months of exercise training.

Trial registration

The trial was registered at www.anzctr.org.au (Registration Number ANZCTR12608000337370) on the 17/07/2008 (retrospectively registered).

     

Influence of verapamil therapy on left ventricular performance at rest and during exercise in hypertrophic cardiomyopathy

To determine the hemodynamic effect of verapamil at rest and during exercise, 18 patients with hypertrophic cardiomyopathy were studied before and after 7 weeks of treatment with oral verapamil (maximal dose, 720 mg/day). At rest and at peak exercise, verapamil produced a significant increase in left ventricular (LV) systolic performance in terms of stroke volume index (rest, from 43 ± 11 to 53 ± 11 ml/m², p < 0.001; exercise, from 46 ± 11 to 51 ± 10 ml/m², p < 0.01), whereas heart rate decreased (rest, from 81 ± 14 to 70 ± 11 min^?1, p < 0.001; exercise, from 150 ± 21 to 141 ± 18 min^?1, p < 0.01). Cardiac index at rest and during exercise remained unchanged. Systolic vascular resistance did not change at rest, but decreased significantly during exercise (974 ± 243 to 874 ± 174 dynes s cm^?5; p < 0.05). After verapamil administration, pulmonary artery pressures did not change at rest, but decreased significantly during exercise. This was probably due to a shift in the LV pressure-volume relation. The improvement in LV hemodynamics was associated with a significant increase in exercise capacity. The findings of this study indicate that in patients with hypertrophic cardiomyopathy, hemodynamic improvement at rest and during exercise can be achieved by chronic administration of verapamil.     

Systemic inhibition of nitric oxide synthesis in non-diabetic individuals produces a significant deterioration in glucose tolerance by increasing insulin clearance and inhibiting insulin secretion

Aims/hypothesis

Endogenous NO inhibits insulin release in isolated beta cells and insulin-degrading enzyme activity in hepatocytes, while NO release from endothelial cells has been suggested to enhance insulin action. We assessed the overall effect of systemic inhibition of endogenous NO synthesis on glucose homeostasis in humans.

Methods

Twenty-four non-diabetic volunteers underwent two hyperglycaemic (+7 mmol/l) clamps with either saline or L-NG-nitroarginine methyl ester (l-NAME, at rates of 2.5, 5, 10 and 20 μg?min^?1?kg^?1) infusion. Another five volunteers underwent an OGTT with either saline or l-NAME (20 μg?min^?1?kg^?1) infusion. Blood pressure and heart rate were measured to monitor NO blockade; during the OGTT, endothelial function was assessed by peripheral arterial tonometry and insulin secretion by C-peptide deconvolution and insulin secretion modelling.

Results

Compared with saline, l-NAME at the highest dose raised mean blood pressure (+20?±?2 mmHg), depressed heart rate (?12?±?2 bpm) and increased insulin clearance (+50%). First-phase insulin secretion was impaired, but insulin sensitivity (M/I index) was unchanged. During the OGTT, l-NAME raised 2 h plasma glucose by 1.8 mmol/l (p?<?0.01), doubled insulin clearance and impaired beta cell glucose sensitivity while depressing endothelial function.

Conclusions/interpretation

In humans, systemic NO blockade titrated to increase blood pressure and induce endothelial dysfunction does not affect insulin action but significantly impairs glucose tolerance by increasing plasma insulin clearance and depressing insulin secretion, namely first-phase and beta cell glucose sensitivity.     

Determination of new prediction formula for nasal continuous positive airway pressure in Turkish patients with obstructive sleep apnea syndrome

Background

Race/ethnicity may play an important role in determining body size, severity of obstructive sleep apnea syndrome (OSAS), and effective continuous positive airway pressure (CPAP) (Peff). Turkey is composed of different ethnic groups. Therefore, the aims of this study were to determine new prediction formula for CPAP (Ppred) in Turkish OSAS patients, validate performance of this formula, and compare with Caucasian and Asian formulas.

Methods

Peff of 250 newly diagnosed moderate-to-severe OSAS patients were calculated by in-laboratory manual titration. Correlation and multiple linear regression analysis were used to model effects of ten anthropometric and polysomnographic variables such as neck circumference (NC) and oxygen desaturation index (ODI) on Peff. New formula was validated in different 130 OSAS patients and compared with previous formulas.

Results

The final prediction formula was $ {\text{Ppred}} = \left( {0.{148} \times {\text{NC}}} \right) + \left( {0.0{38} \times {\text{ODI}}} \right) $ . When Peff of control group was assessed, it was observed that mean Peff was 8.39?±?2.00?cmH₂O and Ppred was 8.23?±?1.22?cmH₂O. Ppred was within ±3?cmH₂O of Peff in 96.2% patients. Besides, Peff was significantly correlated with new formula, and prediction formulas developed for Caucasian and Asian populations (r?=?0.651, p?<?0.001, r?=?0.648, p?<?0.001, and r?=?0.622, p?<?0.001, respectively).

Conclusions

It is shown that level of CPAP can be successfully predicted from our prediction formula, using NC and ODI and validated in Turkish OSAS patients. New equation correlates with other formulas developed for Caucasian and Asian populations. Our simple formula including ODI, marker of intermittent hypoxia, may be used easily in different populations.     

Neuromuscular adaptations to concurrent training in the elderly: effects of intrasession exercise sequence

The aim of this study was investigate the effects of different intrasession exercise orders in the neuromuscular adaptations induced by concurrent training in elderly. Twenty-six healthy elderly men (64.7?±?4.1 years), were placed into two concurrent training groups: strength prior to (SE, n?=?13) or after (ES, n?=?13) endurance training. Subjects trained strength and endurance training during 12 weeks, three times per week performing both exercise types in the same training session. Upper and lower body one maximum repetition test (1RM) and lower-body isometric peak torque (PTiso) and rate of force development were evaluated as strength parameters. Upper and lower body muscle thickness (MT) was determined by ultrasonography. Lower-body maximal surface electromyographic activity of vastus lateralis and rectus femoris muscles (maximal electromyographic (EMG) amplitude) and neuromuscular economy (normalized EMG at 50 % of pretraining PTiso) were determined. Both SE and ES groups increased the upper- and lower-body 1RM, but the lower-body 1RM increases observed in the SE was higher than ES (35.1?±?12.8 vs. 21.9?±?10.6 %, respectively; P?<?0.01). Both SE and ES showed MT increases in all muscles evaluated, with no differences between groups. In addition, there were increases in the maximal EMG and neuromuscular economy of vastus lateralis in both SE and ES, but the neuromuscular economy of rectus femoris was improved only in SE (P?<?0.001). Performing strength prior to endurance exercise during concurrent training resulted in greater lower-body strength gains as well as greater changes in the neuromuscular economy (rectus femoris) in elderly.     

‘Exercise snacks’ before meals: a novel strategy to improve glycaemic control in individuals with insulin resistance

Aims/hypothesis

The aim of this study was to investigate whether small doses of intense exercise before each main meal (‘exercise snacks’) would result in better blood glucose control than a single bout of prolonged, continuous, moderate-intensity exercise in individuals with insulin resistance.

Methods

Nine individuals completed three exercise interventions in randomised order. Measures were recorded across 3 days with exercise performed on the middle day, as either: (1) traditional continuous exercise (CONT), comprising 30 min moderate-intensity (60% of maximal heart rate [HR_max]) incline walking before dinner; (2) exercise snacking (ES), consisting of 6?×?1 min intense (90% HR_max) incline walking intervals 30 min before each meal; or (3) composite exercise snacking (CES), encompassing 6?×?1 min intervals alternating between walking and resistance-based exercise, 30 min before meals. Meal timing and composition were controlled within participants for exercise interventions.

Results

ES attenuated mean 3 h postprandial glucose concentration following breakfast (by 1.4?±?1.5 mmol/l, p?=?0.02) but not lunch (0.4?±?1.0 mmol/l, p?=?0.22), and was more effective than CONT following dinner (0.7?±?1.5 mmol/l below CONT; p?=?0.04). ES also reduced 24 h mean glucose concentration by 0.7?±?0.6 mmol/l (p?=?0.01) and this reduction persisted for the subsequent 24 h (lower by 0.6?±?0.4 mmol/l vs CONT, relative to their baselines; p?=?0.01). CES was just as effective as ES (p?>?0.05 for all glycaemic variables) at improving glycaemic control.

Conclusions/interpretation

Dosing exercise as brief, intense ‘exercise snacks’ before main meals is a time-efficient and effective approach to improve glycaemic control in individuals with insulin resistance.     

Global and regional left ventricular response to bicycle exercise in coronary artery disease. Assessment by quantitative radionuclide angiocardiography.

The left ventricular response to bicycle exercise was evaluated in 60 patients with coronary artery disease and in 13 normal control subjects. Left ventricular ejection fraction, mean normalized ejection rate and regional wall motion were determined using first-pass radionuclide angiocardiograms obtained at rest and again during peak graded bicycle exercise. All normal subjects demonstrated improved left ventricular function with exercise. Left ventricular ejection fraction increased significantly from 67 ± 3 per cent (mean ± SE) at rest to 82 ± 4 per cent with exercise (p < 0.001). Similarly, the left ventricular ejection rate increased significantly from 3.47 ± 0.31 sec^?1 to 6.53 ± 0.42 sec^?1(p < 0.001). In contrast, in 44 of 60 patients with coronary artery disease, the ejection fraction or ejection rate either decreased or remained the same with exercise. New or exaggerated regional wall motion abnormalities were detected in 28 of 60 patients with coronary artery disease. Over-all, global or regional evidence of compromised left ventricular reserve was found in 48 of 60 patients with coronary artery disease.The major determinant of an abnormal left ventricular response to exercise was the presence or absence of electrocardiographic evidence of myocardial ischemia. Left ventricular ejection fraction decreased or remained the same with exercise in all patients with coronary artery disease and electrocardiographic ischemia. New regional wall motion abnormalities were detected in 20 of these patients. In this group, the left ventricular ejection fraction decreased from 66 ± 2 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001), whereas the ejection rate was unchanged by exercise (rest 3.33 ± 0.21 sec^?1; exercise 3.34 ± 0.22 sec^?1, p > 0.05). Of the 30 patients with coronary artery disease who exercised to symptom-limiting fatigue without electrocardiographic ischemia, 18 demonstrated compromised left ventricular reserve with exercise. Twelve of the remaining patients with coronary artery disease had normal left ventricular reserve, in eight of whom ventricular function was completely normal both at rest and during exercise. In this group exercised to fatigue, the left ventricular ejection fraction increased from 53 ± 4 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001). The ejection rate also increased from 2.48 ± 0.24 sec^?1 to 3.67 ± 0.39 sec^?1 (p < 0.001). The direction and magnitude of the left ventricular responses to exercise were not affected by long-term oral propranolol administration in 22 patients. Based upon either abnormal exercise left ventricular reserve or abnormal global and regional left ventricular function at rest, the over-all sensitivity of this radionuclide technic for the detection of coronary artery disease was 87 per cent (52 of 60 patients). These data demonstrate that exercise ventricular performance studies provide important physiologic insights into left ventricular functional reserve as well as a sensitive noninvasive approach for the detection of coronary artery disease.     

Exercise as a Vital Sign: A Quasi-Experimental Analysis of a Health System Intervention to Collect Patient-Reported Exercise Levels

BACKGROUND

Lack of regular physical activity is highly prevalent in U.S. adults and significantly increases mortality risk.

OBJECTIVE

To examine the clinical impact of a newly implemented program (“Exercise as a Vital Sign” [EVS]) designed to systematically ascertain patient-reported exercise levels at the beginning of each outpatient visit.

DESIGN AND PARTICIPANTS

The EVS program was implemented in four of 11 medical centers between April 2010 and October 2011 within a single health delivery system (Kaiser Permanente Northern California). We used a quasi-experimental analysis approach to compare visit-level and patient-level outcomes among practices with and without the EVS program. Our longitudinal observational cohort included over 1.5 million visits by 696,267 adults to 1,196 primary care providers.

MAIN MEASURES

Exercise documentation in physician progress notes; lifestyle-related referrals (e.g. exercise programs, nutrition and weight loss consultation); patient report of physician exercise counseling; weight change among overweight/obese patients; and HbA1c changes among patients with diabetes.

KEY RESULTS

EVS implementation was associated with greater exercise-related progress note documentation (26.2 % vs 23.7 % of visits, aOR 1.12 [95 % CI: 1.11–1.13], p?<?0.001) and referrals (2.1 % vs 1.7 %; aOR 1.14 [1.11–1.18], p?<?0.001) compared to visits without EVS. Surveyed patients (n?=?6,880) were more likely to report physician exercise counseling (88 % vs. 76 %, p?<?0.001). Overweight patients (BMI 25–29 kg/m², n?=?230,326) had greater relative weight loss (0.20 [0.12 – 0.28] lbs, p?<?0.001) and patients with diabetes and baseline HbA1c?>?7.0 % (n?=?30,487) had greater relative HbA1c decline (0.1 % [0.07 %–0.13 %], p?<?0.001) in EVS practices compared to non-EVS practices.

CONCLUSIONS

Systematically collecting exercise information during outpatient visits is associated with small but significant changes in exercise-related clinical processes and outcomes, and represents a valuable first step towards addressing the problem of inadequate physical activity.     

Stage-related changes in functional capacity in Hodgkin’s disease: assessment by cardiopulmonary exercise testing before initiation of treatment

Our aim was to examine indices of cardiorespiratory capacity at rest and during exercise before initiation of therapy for Hodgkin’s disease. We prospectively studied 24 patients divided into two groups according to the disease stage. Group 1 included eight patients in stage IA and four in stage IIA; group 2 included four patients in stage IIB, six in stage III, and two in stage IV. All patients underwent detailed cardiopulmonary evaluations at rest using electrocardiogram, echocardiogram, spirometry, and measurement of pulmonary diffusing capacity (DLCO), and during exercise using a cardiopulmonary exercise test. Groups 1 and 2 were similar with respect to sex distribution (eight women and four men in each), mean age (35±36 vs37±4.6 years), body mass index, and hemoglobin concentration (12.7±0.2 vs 12.1±0.3 g l⁻¹). All patients had a normal cardiovascular status. All patients in group 1 had normal cardiorespiratory measurements at rest and during exercise. Forced vital capacity was significantly lower in group 2 (84.8±2.7% predicted) than in group 1 (105±3%, P<0.0001), without abnormalities in DLCO or in resting and exercise oxygen diffusion. Likewise, percentage predicted (65±4 vs 97±6, P<0.0002), oxygen pulse at peak exercise (0.12±0.01 vs 0.17±0.01, P<0.001), and slope (8.4±0.3 vs 10.2±0.4, P<0.003) were significantly lower in group 2 than in group 1. Functional capacity during exercise was markedly reduced in patients suffering from Hodgkin’s disease in advanced stages. This loss of exercise capacity appeared mainly related to a peripheral disorder.