Effects of Active Versus Passive Recovery on Power Output During Repeated Bouts of Short Term,High Intensity Exercise

ATP repletion following exhaustive exercise is approximated to be 90-95% complete in 3 minutes, and is crucial in the performance of short duration, high intensity work. Few studies appear to have used this 3-minute interval in the investigation of recovery modes, blood lactate accumulation and power output. Thus, our aim was to investigate changes in peak power (PP), average power (AP) and blood lactate during repeated bouts of high intensity, short duration cycling, comprising active and passive recovery modes lasting 3 minutes. Seven male cyclists (age 21.8±3.3 yrs, mass 73.0±3.8kgs, height 177.3±3.4cm) performed both an active (3 min at 80rpm & 1kg resistance) and a passive recovery (no work between bouts) protocol. Following a warm-up, subjects performed six 15-second maximal sprints against a fixed workload of 5.5kg. Mean PP across the six trials was 775±11.2Watts (W) and 772±33.4W for active and passive protocols respectively; whereas mean AP was 671±26.4W and 664±10.0W, respectively. Neither was significantly different. There was a significant difference within trials for both peak power and average power (p<0.05), with both values decreasing over time. However, the decrease was significantly smaller for both PP and AP values during the active recovery protocol (p<0.05). In the current study, variation in power output cannot be explained by lactate values, as values did not differ between the active and passive protocol (p=0.37). Lactate values did differ significantly between trials within protocols (p<0.05). The results of this study suggest that an active recovery of 3 minutes between high intensity, short duration exercise bouts significantly increases PP and AP compared to a passive recovery, irrespective of changes in blood lactate levels.Key words: Anaerobic power, light exercise, lactate, power output     

Short Bouts of Intensive Exercise During the Workday Have a Positive Effect on Neuro‐cognitive Performance

Beside its positive impact on physical health, exercise is indicated to positively affect cognitive performance based on a relocation of cortical activity. This study examined the influence of different types of breaks on cognitive performance and related cortical activity in office‐based employees. Breaks were filled with exercise, resting or a usual break and a control condition where employees continued working without any break. Cognitive performance was assessed using the d2‐R test and two commercially available cognitive tasks. Brain cortical activity was recorded using electroencephalography before and after breaks. Individual's mood was analysed using a profile of mood state. Results indicate a positive effect of a 3‐min boxing intervention on cognitive performance, mirrored by a decrease in prefrontal cortex activity. Although perceived psychological state was increased after the usual break, this is reflected in neither cortical activity nor cognitive performance. With respect to the fact that also bike activity resulted an increase in prefrontal alpha‐2 activity, a positive effect of exercise on neuro‐cognitive performance can be stated. Health and economic benefits may result from brief physical activity breaks and help to maintain workplace performance and job satisfaction. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of Naloxone Reversal on CO2 Output, Oxygen Uptake and Cardiac Index During Recovery from Fentanyl-Supplemented Anaesthesia

For reversal of contingent residual narcotic depression after fentanyl administration during balanced anaesthesia, the effect of 0.08 mg of naloxone on CO₂ output, O₂ uptake and cardiac index was studied immediately after extubation. This dose maintained normocapnia (5.7 kPa) during early recovery, while in the control group slight hypercapnia was present (6.0 kPa). No significant differences, however, could be detected between the groups in CO₂ output, O₂ uptake or cardiac index. When 0.16 mg of naloxone was given to six other patients 10 min after the anaesthesia, when spontaneous respiration had stabilized on the same level as in the control group, significant increases in respiratory minute volume and rate and CO₂ output were recorded as compared with the respective prenaloxone levels. O₂ uptake increased with simultaneous improvement of Pa_O2 and the cardiac index also increased significantly. A slight but highly significant increase in CO₂ output was detected after 0.16 mg of naloxone in six patients during anaesthesia and volume-controlled IPPV. A significant increase in Pa_cO2 was also measured. These findings indicate that if naloxone is used postoperatively, a significant metabolic increase may take place due to increased muscular work, restlessness and shivering. Ventilation and cardiac output were adequate for demand under present conditions using 2 μg/kg of naloxone, but careful titration of naloxone is recommended in order to avoid harmful metabolic changes.