[Reactions of the cardiopulmonary and the motor system in work with medium-sized muscles]. / Reaktionen des kardiopulmonalen und des motorischen Systems bei Arbeit mit mittleren Muskelmassen.

Three groups of untrained males and two groups of untrained women (aged 20...49 years) carried out one-arm cranking with defined loads. All derived parameters of the cardiopulmonary and motor systems showed a load-dependent behaviour. There were sex-differences in heart rate, oxygen uptake and iEMG. The physical endurance limit was determined by 10 watts for males and 5 watts for women.

[Sex- and age-related differences in blood pressure response to local muscular work during noise]. / Geschlechts- und altersbedingte Differenzen im Blutdruckverhalten bei lokaler Muskelarbeit unter Lärm.

During noise exposure (90 dB [A]) and during local muscular work (30% MVC) combined with noise (90 db [A]) the blood pressure was measured in 20 men and 20 women (20-29 years; 30-39 years). In the group of younger subjects the blood pressure was taken also during the recovery period of 60 minutes. Age- and sex-related differences in blood pressure response were observed not only during noise exposure but also during combined exposure. The different return of the diastolic blood pressure to the resting value after the period of combined exposure referred to sex-related differences in the response of the cardiovascular system during the recovery period, too.

[Reaction of the cardiovascular system with lifting and lowering of loads]. / Reaktion des Herzkreislaufsystems beim Anheben und Absetzen von Lasten.

It was investigated the influence of lifting and lowering of loads on the systolic, diastolic blood pressure and on the heart rate. Male subjects had to move 20 kg and female subjects 10 kg in different ways (2 different working frequencies and 3 back bending angles). At higher working frequencies the heart rate in men and women was in the range of the physical endurance limit. An important finding was the difference in the diastolic blood pressure response during lifting and lowering of loads with the higher working frequency in men.

[Local muscle work and noise and their effect on the amplitude of the finger pulse]. / Lokale Muskelarbeit und Lärm in ihrer Wirkung auf die Fingerpulsamplitude.

The finger pulse amplitude of 10 healthy men (aged 20 to 30 years) was measured during noise (70, 80 and 90 dBA) and combined exposure (local muscular work with 30% MVC and noise with 70, 80 or 90 dBA) and during a recovery phase of 60 min. The finger pulse amplitude was reduced only during noise exposure with 90 dBA and was increased during the combined exposures. A continuous decrease of the finger pulse amplitude was observed during the recovery phases. Differences between noise exposure and combined exposure do not exist. The findings were discussed as the risk of hypertension in workers exposed to noise.

Changes of the EMG and its relationship to the cardiopulmonary parameters during two-arm cranking of disabled men.

During two-arm cranking in 5 groups of men (able-bodied and leg-disabled with different states of training; wheelchair-dependents with basket-ball training) the behaviour of parameters of the motor and cardiopulmonary system (iEMG, heart rate, oxygen uptake) was investigated. On the basis of stepwise increasing physical work up to exhaustion the group of swimtrained leg-disabled men showed the highest physical working capacity. The lowest physical fitness was found in wheelchair-dependent men.

[Muscular burden in current work activities exemplified by cash register work sites]. / Zur muskulären Beanspruchung bei modernen Arbeitstätigkeiten am Beispiel des Kassenarbeitsplatzes.

21 cash register operators (aged 18 to 49 years) have been studied in an industrial study. The investigation included the measurement of heart rate, bioelectrical muscle activity of the right and left M. biceps brachii and M. deltoideus and muscular endurance at 50% MVC. There were significant relationships between the movement of the left arm and the heart rate and the load of articles and the heart rate. The results in bioelectrical activity showed that there were a muscular load in the right and left muscles and findings of muscular fatigue in frequency distribution and in muscular endurance.

Sex- and age-related blood pressure response to dynamic work with small muscle masses.

Four groups of subjects of different ages and sex (group I: 20-29 years, women; group II: 20-29 years, men; group III: 30-39 years, women; group IV: 30-39 years, men) undertook dynamic one-hand work (load range 40%-80% of maximum voluntary contraction, at 60 working cycles/min) to allow a study of cardiovascular responses as shown by the resultant changes in blood pressure and heart rate. During fatiguing dynamic one-hand work, there was a large increase in systolic and diastolic blood pressures in both sexes after a few minutes. For all load levels, the systolic blood pressure was found to be higher by about 4 kPa in men (groups II and IV) than in women (groups I and III). Other age-related differences became evident in the diastolic blood pressure changes. The values obtained for the older groups were higher than those in the two younger groups. These differences in blood pressure response are possibly due to sex-related differences in the release of catecholamines, or to age-related organic changes in the vessels.

Sex- and age-related behaviour of the integrated EMG during one-arm cranking.

There are load-dependent increases in the bioelectrical activity (iEMG) of muscles of the shoulder and the right upper extremity and selected parameters of the cardiopulmonary system. At comparable loads the amplitudes of the EMG were higher in the group of men than in the group of women. The iEMG values were found to be higher in the younger group of women than in the older one. The higher values of iEMG of the younger women corresponded to a higher oxygen uptake and higher heart rate as well as to a lower physical endurance. The physical endurance limit (derived from behaviour of the EMG) was estimated at 5 watts (women) and 10 watts (men).

Physiological effects of dynamic hand work in subjects of different age and sex.

Thirty untrained subjects (group 1: 10 female, 20-30 years; group 2: 10 female, 36-46 years; group 3: 10 males, 20-30 years) performed dynamic hand work on a hand-grip dynamometer at loads varying from 20 to 100% MVC and three different working frequencies (20, 40, and 60 cpm). The mechanical muscle activity, the iEMG and the R-R interval were measured throughout the exercise. Before and after each exercise, the maximal hand-grip force (MVC) was determined together with the iEMG and the R-R interval. With the loads increasing gradually, the mean values of the duration of the contraction phase and of the iEMG of the four muscles increased in all test groups, but the duration of the rest phase and R-R interval decreased. Through an Analysis of Variance, evidence of systematic differences between the test groups was significant for the R-R interval only, while the effects of the loads (with exception of the rest phase) and of the working frequency proved significant for all parameters. The MVC, the iEMG and the R-R interval measured before and after the exercise did not show significant differences. This indicates that the exercise was not fatiguing.