Respiratory gas analysis as an indicator for metabolic strain during exercise has a long history. First introduced in the 18th century, huge gas collectors served for the determination of oxidative energy delivery. While still being accepted as accurate, this particular method delivers data of low temporal resolution only. Further developments of gas analysis techniques therefore focused on a higher density of data. When algorithms became available for indispensable calculations, the so-called "breath-by-breath" (BBB) method was established some decades ago. Thereby, the term BBB in the narrower sense means that a particular physiologic value is determined for each of a subject's single respiratory cycles. Reliable application of this approach depends on the performance of available computer systems, the quality of the analyzing software routines, and the responsiveness of the gas analyzers. Thus, it appears that even nowadays technical progress is continuing in this area. This review describes technical aspects and prerequisites of the BBB approach and its specific areas of application.

Although the drop of PaO2 was comparable, stair-climbing resulted in more prolonged hyperinflation of the lungs, higher blood lactate production and more dyspnea than walking. The walking distance was not related to the time needed to manage stair-climbing. Therefore, pathophysiological changes during the 6-min walking test do not anticipate those during stair-climbing in patients with severe COPD.

The Race Across America, a 4800-km nonstop cycle race, is one of the most demanding endurance sports events. We display the racing strategy, power output, HR, hormonal levels, and inflammatory markers of an athlete before and during the race, which he completed in 10 d 23 h.The athlete showed physiological characteristics of a well-trained (nonelite) cyclist (V˙O2peak=63 mL·min·kg, heart volume=11.3 mL·kg). The race was mainly performed at low intensities (mean ± SD: power output=141 ± 76 W, HR=117 ± 14 bpm). During the race, testosterone levels dropped initially by 30-40% and returned to baseline toward the end. Cortisol remained elevated throughout (+75%-90% compared with baseline). Markers of inflammation (C-reactive protein), dehydration, and protein catabolism (albumin) were not affected. The athlete used a race strategy with regular sleeping breaks (total rest=91 h, 45 h of sleep).Contrasting conventional racing strategies for the Race Across America, which aim at minimizing sleep and maximizing ride time, our case demonstrates that by emphasizing regular recovery and sleep, such alternative strategy might lead an equally successful race result.

Stimulated hematopoiesis is observed in the bone marrow of endurance-trained athletes by magnetic resonance imaging (MRI) independent of the hemoglobin concentration (hematocrit or erythrocyte count) or circulating reticulocytes, but may be related to blood volume (BV). This study determined whether hyperplasia of hematopoietic bone marrow of professional cyclists correlates with their red cell volume (RCV). Twelve male professional cyclists (mean +/- SD; 20.2 +/- 1.4 years, 69.0 +/- 4.5 kg, VO2max 64.4 +/- 4.6 ml/min/kg, BV 7257 +/- 884 ml, RCV 2990 +/- 299 g) completed an MRI of the lumbar spine, a total BV determination using a CO-rebreathing method and a graded exercise testing within two consecutive days. Significant correlations were found between performance and BV data. A significant correlation existed also between the signal intensity of the Turbo inversion-recovery sequence with short inversion time (Turbo-STIR) and BV (r (2) = 0.47, P < 0.05), RCV (r (2) = 0.56, P < 0.05) and plasma volume (r (2) = 0.39, P < 0.05) per kilogram body mass. The present study provides evidence of stimulated erythropoiesis with hyperplasia of the hematopoietic bone marrow of endurance athletes explaining their large RCV.

The metabolic and physiological assessment of physical performance includes methods for the objective measurement of the endurance capacity of sportsmen or the cardiopulmonary function of patients. The correct application of metabolic physical performance diagnostics requires a detailed knowledge of stress physiology and also experience in dealing with the methods of performance diagnostics. The basic method for assessment of the physical performance is ergometry with simultaneous recording of physiological parameters such as heart rate, blood lactate concentration or breath analysis (spiroergometry). Different concepts and software techniques are available to interpret the results and to perform training control. Newer approaches to implement statistical and prognostic methods in the automated analysis algorithms.

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Abstract:Background: Exercise-induced diaphragmatic fatigue (DF) is conventionally considered to reflect impaired diaphragm function resulting from load imposed on the diaphragm during exercise and is known to be reduced by the application of non-invasive ventilation (NIV) during heavy-intensity exercise testing (HEET). On that physiological condition NIV applied for diaphragm unloading during recovery from exercise should be capable of accelerating recovery from DF and therewith prolonging exercise time to exhaustion and limiting the development of DF during a subsequent HEET compared to recovery during spontaneous breathing.Methods: Seven highly-trained subjects (V'O 2max 62.7±7.8 ml/kg/min) performed four HEET at 85% V'O 2max with 60 min of recovery during I spontaneous breathing and II NIV between two HEET.Results: Twitch transdiaphragmatic pressure (TwPdi) during supramaximal magnetic phrenic nerve stimulation decreased (p<0.04) following first HEET and subsequently completely recovered (p>0.2) during I and II. Following second HEET TwPdi comparably decreased (I 0.24±0.21 vs II 0.32±0.29 kPa; p=0.17). Exercise time to exhaustion during second HEET was equal during I and II (I 514±49 vs II 511±92 s; p=0.88). Conclusions:In conclusion, NIV applied for diaphragm unloading during recovery following HEET does neither affect recovery from DF nor subsequent exercise performance thereby providing further evidence that DF might reflect postexercise diaphragm shielding rather than impaired diaphragm function.

Zusammenfassung Zielstellung Erste Ergebnisse aus Aktivitätsbefragungen deuten darauf hin, dass sich die sportliche Aktivität innerhalb der Kontaktbeschränkungen zur Eindämmung des Coronavirus im Frühjahr 2020 verringert haben könnte. Die Coronavirus-Pandemie stellt im Besonderen die Beschäftigten im Gesundheitswesen vor große Herausforderungen. Daher soll untersucht werden, ob die Maßnahmen zur Pandemieeingrenzung einen Einfluss auf das Aktivitätsverhalten von Beschäftigten im öffentlichen Dienst haben. Methode Mit einer retrospektiven Querschnittserhebung wurde das Aktivitätsverhalten in drei Einrichtungen des öffentlichen Dienstes vor und während der Maßnahmen gegen das Coronavirus im April 2020 mit einer Onlineversion des Freiburger Aktivitätsfragebogens erhoben. Mittels Wilcoxon-Tests bei verbundenen Stichproben mit einem Signifikanzniveau von p < 0,05 wurde das Aktivitätsverhalten auf Unterschiede vor gegenüber während den Kontaktbeschränkungen in Minuten/Woche und MET-Min/Woche untersucht. Ergebnisse An der Befragung haben n = 1797 Beschäftigte (36,0 % männlich, 63,9 % weiblich und 0,1 % divers) teilgenommen. Für die Sportaktivität konnte ein relevanter (p < 0,05) Unterschied in den Medianen (Mdn) der Aktivitäten pro Woche vor (Mdn = 180 min) und während (Mdn = 120 min) der geltenden Kontaktbeschränkungen gemessen werden. Auch der Energieverbrauch durch Aktivität sank innerhalb der Kontaktbeschränkungen. Schlussfolgerung Die Maßnahmen zur Pandemieeingrenzung haben zu einer Reduzierung des Aktivitätsverhaltens geführt. Insbesondere treiben weniger Beschäftigte Sport. Dies könnte in Zusammenhang mit der Schließung von Fitnessstudios stehen, da diese Aktivitäten besonders reduziert wurden. Die reduzierte Aktivität kann zu ungünstigen individuellen Risikoprofilen führen, die es in der Folge zu kompensieren gilt.