Blood flow and metabolic control at the onset of heavy exercise

The rate of increase in oxygen uptake (VO2) at the onset of a bout of heavy exercise is faster if it is preceded by a similar bout of heavy exercise. We tested the hypothesis during heavy leg exercise that leg blood flow (LBF) and VO2 would both be elevated during the adaptive phase. On three separate days, six healthy young men completed two bouts of 6-minutes of knee extension / flexion exercise at about 85% VO2peak separated by 5-minutes 0-watt exercise on an electrically braked ergometer. LBF was determined by Doppler ultrasound. In the second exercise bout, LBF and VO2 were significantly elevated in the baseline before exercise and throughout the exercise. Both the mean response time (time to 63% of difference between baseline and calculated end value) and the difference in VO2 between minutes 3 and 6 of exercise indicated significantly faster attainment of the end exercise value in the second heavy exercise bout. These data showing the elevated LBF in the second bout of heavy exercise support the link between O2 delivery and the adaptation of oxidative metabolism at the onset of heavy exercise

Sleep slow-wave homeostasis and cognitive functioning in children with electrical status epilepticus in sleep

Study objectives: Encephalopathy with electrical status epilepticus in sleep (ESES) is characterized by non-rapid eye movement (non-REM)-sleep-induced epileptiform activity and acquired cognitive deficits. The synaptic homeostasis hypothesis describes the process of daytime synaptic potentiation balanced by synaptic downscaling in non-REM-sleep and is considered crucial to retain an efficient cortical network. We aimed to study the overnight decline of slow waves, an indirect marker of synaptic downscaling, in patients with ESES and explore whether altered downscaling relates to neurodevelopmental and behavioral problems. Methods: Retrospective study of patients with ESES with at least one whole-night electroencephalogram (EEG) and neuropsychological assessment (NPA) within 4 months. Slow waves in the first and last hour of non-REM-sleep were analyzed. Differences in slow-wave slope (SWS) and overnight slope course between the epileptic focus and non-focus electrodes and relations to neurodevelopment and behavior were analyzed. Results: A total of 29 patients with 44 EEG ~ NPA combinations were included. Mean SWS decreased from 357 to 327 µV/s (-8%, p < 0.001) across the night and the overnight decrease was less pronounced in epileptic focus than in non-focus electrodes (-5.6% vs. -8.7%, p = 0.003). We found no relation between SWS and neurodevelopmental test results in cross-sectional and longitudinal analyses. Patients with behavioral problems showed less SWS decline than patients without and the difference was most striking in the epileptic focus (-0.9% vs. -8.8%, p = 0.006). Conclusions: Slow-wave homeostasis-a marker of synaptic homeostasis-is disturbed by epileptiform activity in ESES. Behavioral problems, but not neurodevelopmental test results, were related to severity of this disturbance