J. Ilmarinen

Physical training intervention in female shift workers: I. The effects of intervention on fitness, fatigue, sleep, and psychosomatic symptoms

A physical training intervention was carried out on 75 nurses and nursing aides working irregular shifts to determine the effects of such an intervention on health, sleep-wakefulness and adaptation to shiftwork. The study design and changes in physical fitness, fatigue, sleep and psychosomatic symptoms are examined. Training (T) and control (C) groups were built randomly from matched sets of subjects. Questionnaire, laboratory and field studies were done before and after a controlled physical training programme lasting four months. Maximal oxygen consumption and muscle strength increased and heart rates at rest and at work decreased significantly in the T but not in the C group. General fatique during the shift cycle, and fatigue during the night shifts were reduced, whereas fatigue during the evening shifts increased owing to the intervention. Sleep length increased slightly and musculoskeletal symptoms were reduced. The results suggest that moderate physical training increases the physical fitness of fe...

Physical training intervention in female shift workers: II. The effects of intervention on the circadian rhythms of alertness, short-term memory, and body temperature

The effects of a physical training intervention on the circadian rhythms of alertness, short-term memory performance (SAM-test) and oral temperature (t 0) were studied in 75 nurses and nursing aides working irregular shifts in a hospital. Measurements were made every two hours during the days of one morning and two night shifts. In the training group (T), fatigue decreased significantly during the night but not during the day compared to the control group (C). No significant changes were found in the circadian rhythms of the SAM-test and t 0 between the groups, but inside the T group, performance in the SAM-test improved significantly during the day and night shifts, and the mesor and amplitude of t 0 decreased during the day of a morning shift. The results suggest that physical training can induce changes in the circadian rhythms of shift workers which may be interpreted as an adaptation to shift work.

Physical Fitness and Other Individual Factors Relating to the Shiftwork Tolerance of Women

Maximal oxygen consumption (VO2max), muscle strength (MS) and physical activity were compared to age, shiftwork experience, morningness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO2max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculoskeletal symptoms and better sleep quality of the subjects. In different shifts, fatigue, sleep length and quality were influenced most by morningness. It is concluded that physical fitness is an important individual factor explaining the variations of shiftwork tolerance in women.

The Relation of Age to the Adjustment of the Circadian Rhythms of Oral Temperature and Sleepiness to Shift Work

The relation of age to the adjustment of the circadian rhythms of oral temperature (T0) and sleepiness (S) in shift work was studied. 145 healthy female nurses underwent detailed laboratory and field measurements. Self-rated sleepiness, and oral temperature measured with a special extended-scale mercury thermometer, were recorded at 2 hr intervals during a morning (M) and 2 consecutive night (N) shifts. Sleeping times were registered during the same days. The results were analyzed separately in the age-groups of 22-29, 30-39 and 40-49-year-old subjects. From the morning shift to the second night shift day, the oral temperature and sleepiness acrophases shifted significantly (p less than 0.001) forward in all age groups. The amplitude decreased in the youngest and in the 30-39-year old age groups but not in the oldest age group. During the second night shift day, the acrophases and amplitudes of oral temperature rhythms were significantly different (P less than 0.05) between the groups, but there were no significant differences by age in the change of the circadian rhythms from morning to the second night shift days. The results thus fail to corroborate that physiological adjustment to night work would be influenced by age.

Untersuchungen über unterschiedliche präventive effekte von habituellen körperlichen Aktivitäten in beruf bzw. freizeit

SummaryOne hundred twenty men, aged 23–60 years and having various professions participated in studies on relationships between daily physical activity and risk factors for coronary heart disease (CHD). The daily physical activity at work was determined by means of heart rate recordings with an ambulatory monitoring system and of activity recordings according to Edholm over the whole shift. Where necessary, oxygen consumption was also measured. The type of load and strain at work was assessed with a standardised German version of the “Position Analysis Questionnaire” (AET). The habitual leisure time training behaviour was determined retrospectively by standardised interview technique. The risk factors were determined in accordance to WHO recommendations. Workers with high physical load on the job but with low energy expenditure during leisure time had a higher prevalence of the risk factors blood pressure, cigarette smoking, adiposity, and chest pain than workers with similar or lighter jobs but with physically active leisure habits. The intensely smoking workers with physically heavy work and inactive leisure seem to carry the highest risk.ZusamenfassungAn 120 Männern im Alter von 23–60 Jahren aus verschiedenen Beruwfsgruppen mit unterschiedlich schwerer körperlicher Arbeit wurde das Ausmaß der habituelen täglichen körperlichen Aktivät untersucht und zu Risikoindikatoren für Koronarerkrankungen im Beziehung gesetzt. Die tägliche körperliche Aktivität wurde in ihrem beruflichen Teil über ganzschichte arbeitsphysiologische Studien mit Herzfrequenzmessungen mit Hilfe von Cardiocordern und Positionsstudien im Anlehnung an Edholm durchgefürht und, falls nörtig, mit O2-Verbrauchmessungen erfaßt. Die Art der täglichen beruflichen Belastung und Beanspruchung wurde mit einer standardisierten Beobachtungsmethode zur Tätigleitsanalyse (AET) erfaßt. Für den Freizeitbereich wurden die langdauernden Trainingsgewohnheiten retrospektiv über standardisierte Interviewktechniken erhoben. Die wichtigsten Risikofaktoren wurden entsprechend den Vorschalägen der WHO ermittelt.Die Ergebnisse zeigen, daß in ihrer Freizert sportlich inaktive Schwerrauchen, Adipositas und Angina pectoris gegenüber Schwerarbeitern mit hoher sportlicher Aktivität sowie Arbeitern mit leichter körpelicher Aktovität im Beruf, aber großer sportlicher Aktivität in der Freizeit aufweisen. Aufgrund der Untersuchung schmint die Gruppe der Schwerarbeiter ohne ausgleichende körperliche Aktivität in der Freizeit die gleichzeitig eine großen Zigarettenkonsum aufweist, besonders gefährdet zu sein.

Untersuchungen ber unterschiedliche prventive effekte von habituellen krperlichen Aktivitten in beruf bzw. freizeit@@@Studies on differences in the preventive effects of habitual physical activity in occupation versus leisure time: II. Die wirkung von krperlichen aktivitten im beruf bzw. in der freizeit auf die kardiopulmonale Leistungsfhigkeit@@@II. Effects of physical activity in occupation versus leisure time on physical working capacity

One hundred and twenty men, aged 23--60 years and having various professions participated in studies on relationships between daily physical activity and physical performance capacity (PPC). The determination of daily physical activity at work and of the habitual leisure time activities has been described earlier (Ilmarinen et al. 1980). The determination of physical performance capacity was based on W170, W85% and on predicted VO2 max measured with continuously increasing work load on a bicycle ergometer. The W85% modification corresponds to the working capacity at a heart rate level of 85% of maximal heart rate. Workers with a combination of heavy physical work and active leisure time showed systematically the highest absolute and relative values of PPC. However, although the results indicated that the effect of work activity on PPC was not significant, the effects of leisure time activities on W85% and on VO2 max related to lean body mass were significant. It is concluded that the leisure time sport activities are more important than the physical activity at work in maintaining or increasing the PPC. Aerobic sport activities in leisure time are recommended both for persons with physically heavy and light work.SummaryOne hundred and twenty men, aged 23–60 years and having various professions participated in studies on relationships between daily physical activity and physical performance capacity (PPC). The determination of daily physical activity at work and of the habitual leisure time activities has been described earlier (Ilmarinen et al. 1980). The determination of physical performance capacity was based on W170, W85% and on predicted

EFFECTS OF 10 H TIME ZONE CHANGES ON FEMALE FLIGHT ATTENDANTS' CIRCADIAN RHYTHMS OF BODY TEMPERATURE, ALERTNESS, AND VISUAL SEARCH.

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[Studies on differences in the preventive effects of habitual physical activity in occupation versus leisure time. II. Effects of physical activity in occupation versus leisure time on physical working capacity (author's transl)].

max measured with continuously increasing work load on a bicycle ergometer. The W85% modification corresponds to the working capacity at a heart rate level of 85% of maximal heart rate.Workers wiih a combination of heavy physical work and active leisure time showed systematically the highest absolute and relative values of PPC. However, although the results indicated that the effect of work activity on PPC was not significant, the effects of leisure time activities on W85% and on