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Aims Left atrial strain (LAS) and skeletal muscle endurance demonstrate a linear relationship to peak VO2. Less is known about the relationship between central (cardiac) and peripheral (muscle endurance) limitations of exercise capacity in patients with heart failure (HF). We investigated this relationship using novel cardiac markers such as LAS and left atrial ejection fraction (LAEF). Methods We analysed echocardiographic measurements, cardiopulmonary exercise testing, and isokinetic muscle function in 55 subjects with HF and controls (17 heart failure with preserved ejection fraction -HFpEF, 18 heart failure with reduced ejection fraction-HFrEF and 20 healthy controls). Results Patients with reduced LAEF showed reduced peak VO2: 14.3±3.5 vs. 18.5±3.5 ml/min/kg, p=0.003 and reduced muscle endurance (RME): 64.3±23.9 vs. 88.5±32.3 Nm/kg, p=0.028. Patients with reduced LAS showed similar results. Neither left ventricular global longitudinal strain (LVGLS) nor left atrial volume index (LAVI) were associated with RME. The area under the curve of LAS and LAEF in patients with HF in association with RME were (0.76 vs. 0.80) with 95% confidence interval (CI) (0.59–0.96, p=0.012 vs. 0.63–0.98, p=0.006, respectively). Peak torque of the left leg was associated with E/LAS (E: early diastolic) in patients with HFpEF (r=−0.6, p=0.020). Endurance of the left leg was associated with LAEF (r=0.79, p=0.001) in patients with HFrEF. Conclusion LAS/LAEF are potential cardiac markers in demonstrating the link between cardiac and peripheral limitations of exercise capacity. Thus, integrating LAS/LAEF in the evaluation of exercise intolerance in patients with HF could be useful. Funding Acknowledgement Type of funding sources: None.

Mild motor abnormalities can herald the beginning of Parkinson´s disease but their diagnostic value is limited by multifactorial ageing-related influences on motor function. We characterized mild motor abnormalities in different motor domains by conducting a systematic motor assessment in 20 patients with clinically isolated REM sleep behaviour disorder (iRBD) without parkinsonian motor signs and 20 healthy controls. We addressed the influence of lifestyle factors and age on motor function, which needs to be distinguished from neurodegenerative motor features, and assessed the diagnostic value of innovative and established quantitative motor tests in iRBD. Patients with iRBD showed abnormalities in perceptual motor speed (falling stick test), trunk movement coordination (bend, twist and touch test) and dynamic balance (line walk test) without alterations in simple motor speed (alternate tap test), dexterity (grooved pegboard), static balance (force plate) and gait (timed up and go test). The falling stick test showed the highest diagnostic accuracy in identifying subjects with RBD (ROC-AUC 0.85, p ≤ 0.001). Multivariate analysis revealed physical activity and age as additional determinants of motor test performance. iRBD comprises a wide spectrum of mild motor abnormalities which cannot be verified by established tests for motor speed, gait and balance. The falling stick test, an innovative screening test for perceptual motor speed, provides high diagnostic potential in identifying subjects with subclinical neurodegenerative symptoms before parkinsonian motor signs become apparent. Normative data for physical activity and age need to be obtained to ensure correct interpretation of motor test results in prodromal Parkinson-related disease.

Measurements of exercise-induced metabolic changes, such as oxygen consumption, carbon dioxide exhalation or lactate concentration, are important indicators for assessing the current performance level of athletes in training science. With exercise-limiting metabolic processes occurring in loaded muscles, 31 P-MRS represents a particularly powerful modality to identify and analyze corresponding training-induced alterations. Against this background, the current study aimed to analyze metabolic adaptations after an exhaustive exercise in two calf muscles (m. soleus - SOL - and m. gastrocnemius medialis - GM) of sprinters and endurance athletes by using localized dynamic 31 P-MRS. In addition, the respiratory parameters VO2 and VCO2 , as well as blood lactate concentrations, were monitored simultaneously to assess the effects of local metabolic adjustments in the loaded muscles on global physiological parameters. Besides noting obvious differences between the SOL and the GM muscles, we were also able to identify distinct physiological strategies in dealing with the exhaustive exercise by recruiting two athlete groups with opposing metabolic profiles. Endurance athletes tended to use the aerobic pathway in the metabolism of glucose, whereas sprinters produced a significantly higher peak concentration of lactate. These global findings go along with locally measured differences, especially in the main performer GM, with sprinters revealing a higher degree of acidification at the end of exercise (pH 6.29 ± 0.20 vs. 6.57 ± 0.21). Endurance athletes were able to partially recover their PCr stores during the exhaustive exercise and seemed to distribute their metabolic activity more consistently over both investigated muscles. In contrast, sprinters mainly stressed Type II muscle fibers, which corresponds more to their training orientation preferring the glycolytic energy supply pathway. In conclusion, we were able to analyze the relation between specific local metabolic processes in loaded muscles and typical global adaptation parameters, conventionally used to monitor the training status of athletes, in two cohorts with different sports orientations.