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Biomedical subjects

B Samuelson

Publications and source records attributed to B Samuelson.

6 recordsLinked to original sources
PubMed2001

The effects of double-shifts (15.5 hours) on sleep, fatigue and health.

The aim of the present study was to investigate how "double-shifts" (15.5 hours) affects sleep, fatigue and self-rated health. The study was carried out on male construction workers of which 80% were long-distance commuters. The schedule involved two work periods and each work period involved two double shifts in a row. The subjects filled in a sleep/wake diary at 8 times across a year and a questionnaire at 3 times. They also wore an actigraph during one shift cycle. The results showed that sleepiness, and to a certain extent, mental fatigue increased during double shifts and accumulated across days. The short rest time (8.5 hours) between days caused insufficient sleep and approximately 5.5 hours of sleep was obtained between double shifts. Questionnaire data showed that complaints of insufficient sleep, exhaustion on awakening and pain symptoms increased across the year. It was concluded that a shift system involving double shifts has a negative effect on fatigue, recovery and health-related well-being.

Adult↗
PubMed1989

Influence of vibration on endurance of maximal isometric contraction.

In order to investigate how vibration affects endurance during muscular contraction, knee-joint extension efforts were performed with and without superimposed vibrations. Fourteen healthy non-smoking 20-year-old males performed maximal isometric and sustained knee-joint extension efforts (angle 90 degrees) in sitting posture three times with each leg, with or without vibration. The tests were done once with each leg in a randomly chosen order. The frequency of the vibration was 20 Hz and the acceleration 20 m/s2 RMS, applied in a horizontal sagittal direction to the ankle. The endurance was defined as the time in seconds that it took for the exerted force to decrease by 10% of the initial value. The endurance time averages 22.5 s without vibration and 15.8 s with vibration. The vibratory stress reduced endurance by 6.7 +/- 1.84 s (mean +/- SEM) (P less than 0.005). The difference in maximal force recorded initially was 34 +/- 1.9 N (P less than 0.1). Our conclusion is that vibration may decrease the endurance of maximal och sustained isometric muscular contraction.

Adult↗
PubMed1989

Influence of vibration on work performance during ergometer cycling.

With a view to investigating how vibration affects dynamic working capacity, exercise tests were performed both with and without superimposed vibration. The performance of 8 healthy, non-smoking 20-year-old males exercising on a cycle ergometer at a constant load was studied on four occasions, with and without vibration in a randomly chosen order. The frequency of the vibration, which was applied vertically through the pedals, was 20 Hz and the acceleration was 20 m/s2 RMS. The handlebars and saddle of the cycle were insulated from the vibration. The exercise time averaged 47 min with vibration and 60 min without. The vibratory stress reduced the exercise time by 13 +/- 2.9 min (mean +/- SEM) (P less than 0.005). The average heart rate when the exercise was stopped was 180.3 beats/min with vibration and 180.7 beats/min without. The systolic blood pressure after 20 min averaged 188 mm Hg with vibration and 187 mm Hg without vibration. Both with and without vibration, 6 of the 8 subjects stated that leg fatigue was the cause of their inability to continue pedalling longer. Our conclusion is that in the performance of dynamic muscular work endurance may decrease under the influence of vibration.

Adult↗
PubMed1987

Automatic ergonomic work analysis.

To reduce occupational-related diseases, injuries and impairments to the musculo-skeletal systems, an ergonomics analysis of the work process is necessary. The authors describe a project to develop an automatic ergonomic work analysis method using existing and developed models of work stress factors. It was designed to record the work accurately without disrupting activities, and describe the situation so that production engineers and designers can be supplied with basic information for ameliorative measures. The system determines such parameters as the position and movement of 14 parts of the body, and such measurements as force exerted, range of movement and static stress. A pilot study with a prototype of the system has been completed and tested with simple work sequences.

Journal Article↗