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Purpose Exercise training improves exercise capacity in type 2 diabetes mellitus (T2DM). It remains to be elucidated whether such improvements result from cardiac or peripheral muscular adaptations, and whether these are intensity dependent. Methods 27 patients with T2DM [without known cardiovascular disease (CVD)] were randomized to high-intensity interval training (HIIT, n= 15) or moderate-intensity endurance training (MIT, n= 12) for 24 weeks (3 sessions/week). Exercise echocardiography was applied to investigate cardiac output (CO) and oxygen (O-2) extraction during exercise, while exercise capacity [((V) over dotO(2peak) (mL/kg/min)] was examined via cardiopulmonary exercise testing at baseline and after 12 and 24 weeks of exercise training, respectively. Changes in glycaemic control (HbA1c and glucose tolerance), lipid profile and body composition were also evaluated. Results 19 patients completed 24 weeks of HIIT (n = 10, 66 +/- 11 years) or MIT (n = 9, 61 +/- 5 years). HIIT and MIT similarly improved glucose tolerance (p(Time) = 0.001, p(Interaction) > 0.05), (V) over dotO(2peak )(mL/kg/min ) (p(Time) = 0.001, p(Interaction) > 0.05), and exercise performance (W-peak, (p(Time )< 0.001 p(Interaction) > 0.05). O-2 extraction increased to a greater extent after 24 weeks of MIT (56.5%, p(1) =0.009, p(Time) = 0.001, P-Interaction = 0.007). CO and left ventricular longitudinal strain (LS) during exercise remained unchanged (p(Time )> 0.05). A reduction in HbA1c was correlated with absolute changes in LS after 12 weeks of MIT (r = - 0.792, p = 0.019, LS at rest) or HIIT = - 0.782, p = 0.038, LS at peak exercise). Conclusion In patients with well-controlled T2DM, MIT and HIIT improved exercise capacity, mainly resulting from incre- ments in O-2 extraction capacity, rather than changes in cardiac output. In particular, MIT seemed highly effective to generate these peripheral adaptations.

Aims Type 2 diabetes mellitus (T2DM) is associated with reduced exercise capacity and cardiovascular diseases, both increasing morbidity and risk for premature death. As exercise intolerance often relates to cardiac dysfunction, it remains to be elucidated to what extent such an interplay occurs in T2DM patients without overt cardiovascular diseases. Design: Cross-sectional study, NCT03299790. Methods and results Fifty-three T2DM patients underwent exercise echocardiography (semi-supine bicycle) with combined ergospirometry. Cardiac output (CO), left ventricular longitudinal strain (LS), oxygen uptake (O2), and oxygen (O2) extraction were assessed simultaneously at rest, low-intensity exercise, and high-intensity exercise. Glycaemic control and lipid profile were assessed in the fasted state. Participants were assigned according to their exercise capacity being adequate or impaired (EXadequate: O2peak 0.05). At rest, CO was similar in the EXimpaired group vs. EXadequate group (5.1 ± 1 L/min vs. 4.6 ± 1.4 L/min, P > 0.05) and increased equally during exercise. EXimpaired patients displayed a 30.7% smaller increase in O2 extraction during exercise compared to the EXadequate group (P = 0.016) which resulted in a lower O2 extraction at high-intensity exercise (12.5 ± 2.8 mL/dL vs. 15.3 ± 3.9 mL/dL, P = 0.012). Left ventricular longitudinal strain was similar at rest but increased significantly less in the EXimpaired vs. EXadequate patients (1.9 ± 2.5% vs. 5.9 ± 4.1%, P = 0.004). Conclusions In asymptomatic T2DM patients, an impaired exercise capacity is associated with an impaired response in oxygen extraction and myocardial deformation (LS). Trial registry Effect of High-intensity Interval Training on Cardiac Function and Regulation of Glycemic Control in Diabetic Cardiomyopathy (https://clinicaltrials.gov/ct2/show/NCT03299790).

BACKGROUND: Persons with Multiple Sclerosis have elevated resting serum lactate concentrations compared to healthy controls (HC). OBJECTIVE: To evaluate lactate concentrations during acute exercise and/or following training in MS compared to HC. METHODS: In this retrospective study, blood lactate concentrations (mmol/l) originating from two previous studies were analyzed. Lactate concentrations originated from acute submaximal (MSsubmax; HC, n = 11; MS, n = 32) or maximal (MSmax; HC, n = 20; MS, n = 24) exercise tests and following a 24-week mild to moderate intensity (MSsubmax, n = 12) or 12-week high intensity interval (MSmax, n = 13) exercise intervention. RESULTS: Under submaximal conditions in MS and compared to HC, lactaterest (MS: 2.7 +/- 0.6 vs HC: 2.3 +/- 0.7 was significantly (p < 0.05) elevated. After 24 weeks of mild-to-moderate-intensity exercise training and compared to PRE-values, lactate(bout2) (2.5 +/- 0.7 vs 3.4 +/- 1.1) significantly (p < 0.05) decreased during submaximal testing in MSsubmax. Under maximal conditions, lactatestart (2.3 +/- 1.0 vs 1.7 +/- 0.9) was significantly (p > 0.05) elevated in MS. Twelve weeks of high intensity interval training did not improve this (p > 0.05). CONCLUSIONS: Under the conditions of this retrospective analysis we conclude that lactate concentrations during acute submaximal and maximal exercise in persons with MS are similar compared to healthy controls. Moderate intensity exercise therapy appeared to improve lactate accumulation but high intensity exercise therapy did not.

Muscle weakness and fatigue are primary manifestations of multiple sclerosis (MS), a chronic disease of the central nervous system. Interventions that enhance muscle function may improve overall physical well-being of MS patients. Recently, we described that levels of carnosine, an endogenous muscle dipeptide involved in contractile function and fatigue-resistance, are reduced in muscle tissue from MS patients and a monophasic rodent MS model (experimental autoimmune encephalomyelitis, EAE). In the present study, we aimed to (1) confirm this finding in a chronic EAE model, along with the characterization of structural and functional muscle alterations, and (2) investigate the effect of carnosine supplementation to increase/restore muscle carnosine levels and improve muscle function in EAE. We performed muscle immunohistochemistry and ex vivo contractility measurements to examine muscle structure and function at different stages of EAE, and following nutritional intervention (oral carnosine: 3, 15 or 30 g/L in drinking water). Immunohistochemistry revealed progressively worsening muscle fiber atrophy and a switch towards a fast-twitch muscle phenotype during EAE. Using ex vivo muscle contractility experiments, we observed reductions in muscle strength and contraction speed, but no changes in muscle fatigability of EAE mice. However, carnosine levels were unaltered during all stages of EAE, and even though oral carnosine supplementation dose-dependently increased muscle carnosine levels up to + 94% after 56 days EAE, this did not improve muscle function of EAE mice. In conclusion, EAE mice display significant, yet time-dependent, muscular alterations, and carnosine intervention does not improve muscle function in EAE.

BACKGROUND: Adults with obesity may display disturbed cardiac chronotropic responses during cardiopulmonary exercise testing, which relates to poor cardiometabolic health and an increased risk for adverse cardiovascular events. It is unknown whether cardiac chronotropic incompetence (CI) during maximal exercise is already present in obese adolescents and, if so, how that relates to cardiometabolic health. METHODS: Sixty-nine obese adolescents (body mass index standard deviation score = 2.23 ± 0.32, age = 14.1 ± 1.2 years; mean ± SD) and 29 lean adolescents (body mass index standard deviation score = –0.16 ± 0.84, age = 14.0 ± 1.5 years) performed a maximal cardiopulmonary exercise testing from which indicators for peak performance were determined. The resting heart rate and peak heart rate were used to calculate the maximal chronotropic response index. Biochemistry (lipid profile, glycemic control, inflammation, and leptin) was studied in fasted blood samples and during an oral glucose tolerance test within obese adolescents. Regression analyses were applied to examine associations between the presence of CI and blood or exercise capacity parameters, respectively, within obese adolescents. RESULTS: CI was prevalent in 32 out of 69 obese adolescents (46%) and 3 out of 29 lean adolescents (10%). C-reactive protein was significantly higher in obese adolescents with CI compared to obese adolescents without CI (p = 0.012). Furthermore, peak oxygen uptake and peak cycling power output were significantly reduced (p < 0.05) in obese adolescents with CI vs. obese adolescents without CI. The chronotropic index was independently related to blood total cholesterol (standardized coefficient β = –0.332; p = 0.012) and C-reactive protein concentration (standardized coefficient β = –0.269; p = 0.039). CONCLUSION: CI is more common in the current cohort of obese adolescents, and is related to systemic inflammation and exercise intolerance.

During incremental exercise tests, chronotropic incompetence (CI), which is the inability of the heart rate (HR) to rise in proportion to an increase in metabolic demand, is often observed in patients with type 2 diabetes mellitus (T2DM). Despite the fact that CI is associated with exercise intolerance and elevated risks of development of cardiovascular disease and premature death, this clinical anomaly is often ignored or overlooked by clinicians and physiologists. CI is, however, a significant clinical abnormality that deserves further attention, examination and treatment. The aetiology of CI in T2DM remains poorly understood and is complex. Certain T2DM-related co-morbidities or physiological anomalies may contribute to development of CI, such as altered blood catecholamine and/or potassium levels during exercise, structural myocardial abnormalities, ventricular and/or arterial stiffness, impaired baroreflex sensitivity and cardiovascular autonomic neuropathy. Clinicians should thus be aware of the potential presence of yet undetected anomalies or diseases in T2DM patients who experience CI during exercise testing. However, an effective treatment for CI in T2DM is yet to be developed. Exercise training programmes seem to be the only potentially effective and feasible interventions for partial restoration of the chronotropic response in T2DM, but it remains poorly understood how these interventions lead to restoration of the chronotropic response. Studies are thus warranted to elucidate the aetiology of CI and develop an effective treatment for CI in T2DM. In particular, the impact of (different) exercise interventions on CI in T2DM deserves greater attention in future studies.

Patients with chronic obstructive pulmonary disease (COPD), asthma and interstitial lung diseases (ILD) frequently suffer from cardiovascular comorbidities (CVC). Exercise training is a cornerstone intervention for the management of these conditions, however recommendations on tailoring programmes to patients suffering from respiratory diseases and CVC are scarce. This systematic review aimed to identify the eligibility criteria used to select patients with COPD, asthma or ILD and CVC to exercise programmes; assess the impact of exercise on cardiovascular outcomes; and identify how exercise programmes were tailored to CVC. PubMed, Scopus, Web of Science and Cochrane were searched. Three reviewers extracted the data and two reviewers independently assessed the quality of studies with the Quality Assessment Tool for Quantitative Studies. MetaXL 5.3 was used to calculate the individual and pooled effect sizes (ES). Most studies (58.9%) excluded patients with both stable and unstable CVC. In total, 26/42 studies reported cardiovascular outcomes. Resting heart rate was the most reported outcome measure (n = 13) and a small statistically significant effect (ES = −0.23) of exercise training on resting heart rate of patients with COPD was found. No specific adjustments to exercise prescription were described. Few studies have included patients with CVC. There was a lack of tailoring of exercise programmes and limited effects were found. Future studies should explore the effect of tailored exercise programmes on relevant outcome measures in respiratory patients with CVC.

BACKGROUND AND PURPOSE: Brain derived neurotrophic factor (BDNF) is suggested to play a neuroprotective role in multiple sclerosis (MS). However, the BDNF response to long-term exercise in MS remains unknown. Our objective was to compare resting BDNF profiles of healthy controls (HCs) and persons with relapsing-remitting MS (RRMS) and to investigate the impact of a 24-week exercise intervention on serum BDNF release in MS.METHODS: At baseline, blood BDNF levels were assessed in MS (n = 22, mean Expanded Disability Status Scale 2.6 ± 0.2, mean age 43 ± 2 years) and HCs (n = 19, mean age 47 ± 1 year). Next, persons with MS were randomized to an exercise intervention group (EX, n = 15) or a sedentary control group (SED, n = 7) completing a 24-week randomized controlled trial. In persons with MS, muscle strength, exercise tolerance and body composition were assessed, as compliance measures, at baseline and after 24 weeks.RESULTS: At baseline, the BDNF concentration of persons with RRMS was 21% lower than HCs. Following 24 weeks of intervention, changes in BDNF concentrations differed significantly between EX and SED. In particular, within EX BDNF concentrations increased 13.9% ± 8.8%, whereas it decreased 10.5% ± 4.1% within SED. Furthermore, 24 weeks of exercise induced changes in the compliance measures between EX and SED. In addition, within EX muscle strength, exercise tolerance and lean tissue mass improved, whereas these remained stable within SED.CONCLUSION: In conclusion, BDNF concentration of persons with RRMS was lower compared to HCs and increased after 24 weeks of exercise in persons with MS, compared to the non-exercise MS control group.