Untersuchung zur Tagesperiodik verschiedener Kreislauf-und Atemgr��en bei submaximalen und maximalen Leistungen am Fahrradergometer

Abstract

The maximal aerobic power of six highly trained young cyclist, mean age 16.3 years and mean VO2max 4.9 l/min, was directly measured at intervals of 4 hrs. A Latin square design was used for the test order. At submaximal work of O2-consumption 2.4 to 4.4 l/min no circadian variation of any single function was found. However, at maximal work load the differences between the maxima and minima values were 12.4% for maximal work output (W max), 7.8% for expiratory minute volume (V Emax), 5.7% for maximal aerobic power (VO2max) and 3.4% for maximal heart rate (H Rmax). All the functions--with the exception of VO2max-had their minima at 0300 hrs; the minima of VO2max was reached already at 2300 hours. The maxima-values of V Emax and VO2max were measured at 1500 hrs, of W max and H Rmax at 0700 and of H Rrest at 1900 hrs correspondingly. A one-tailed test showed significant differences between the maxima and minima values of all variables (P less than 0.05). The results suggest a decreased cardiopulmonary working capacity at night. However, this impairment is only of practical importance if the work will be done near the limit of endurance capacity. Besides it will suggest, that the indirect methods for assessing the cardiopulmonary capacity based on VO2max and W170 are not useful at nighttime, because the presuppositions for these methods are limited of the time of day.

Circadian variation of physiological functions related to physical work capacity.

“…The circadian circulatory responses of heart rate at rest and during work obtained in this study confirmed those of earlier studies (3,7,8). In interpreting the heart rate responses, it should be pointed out that the heart rate at night is not low because of less strain but because circadian rhythm exists.…”

“…Although a linear relationship between heart rate and work load can be used for calculations, the V0 2 max will be overestimated at night (7).…”

“…No difference in maximal oxygen consumption (V0 2 max) between day and night was suggested by Wahlberg & Astrand (19). The results of Ilmarinen et al (7) showed no circadian variation of various circulatory and respiratory functions at a submaximal work level, but at the maximum work level a decreased physical work capacity at night was demonstrated. They indicated that the 5-6 % decrease in V0 2 max at night was probably of practical importance only when work is especially heavy.…”

Evaluation von Übungen des Massenanfalls von Verletzten

“…Den Einfluss der Tageszeit auf die Leistungsfähigkeit des Menschen und damit auch von Einsatzkräften belegen zahlreiche Studien aus dem Bereich der Arbeitsphysiologie [18,19]. Dabei schwankt die Leistungsfähigkeit zwischen einem absoluten Minimum gegen 3:00 Uhr nachts [20] und einem Maximum zwischen 16:00 und 18:00 Uhr [21]. Die Verminderung der Leistungsfähigkeit zeigt sich in verlängerten Reaktionszeiten, erhöhten Fehlerraten, einer verringerten Signalerkennungsquote und negativen Auswirkungen auf die Bewältigung kognitiver Aufgaben [18].…”

Circadian Rhythms. Physical Performance as Function of the Time of the Day

“…Also in respect to maximum oxygen intake, significant higher values occur in the daytime as compared to nighttime. During the morning and early afternoon the oxygen intake increases, reaches maximum values at about 18.00 hours and slowly declines during the evening, reaching minimum levels at night (2,7,8).…”