No abstract

The purpose of this study was to verify the timing of triggering in relation to the cardiac cycle in shooting. The test subjects were six Finnish rifle and pistol champions as well as three beginners at shooting. The electrical activity of the trigger finger muscle (m. flexor digitorum superficialis; surface electrodes) and the heart cycle were fed into a two-channel x-t recorder. The movements of the gun were recorded using a laser technique and, at the same time, cardiac cycles were also monitored. Results showed that the champion shooters triggered during diastole whereas the beginners triggered both during diastole and systole. The results of those beginners triggering during diastole were better than those triggering during systole.

No abstract

Keyboard work consists mostly of dynamic contractions of the small muscles of the forearms and hands. This is accompanied by continuous activity in the arm, shoulder and neck muscles keeping the head and hand in the correct position. Eliminating the weight from the arm by means of support and the position of the arms influences the electrical activity of shoulder muscles when working at a keyboard. We studied the influence of elbow angle; as well as that of different arm supports, on electrical activity of upper trapezius muscle during keyboard work in healthy workers and persons suffering from shoulder pains. The measurements were carried out in the laboratory. EMG activities, which where measured as mean square root (RMS)-values at every 100-millisecond period in trapezius muscle when working, were lower, the greater the elbow angle. Furthermore electrical activity decreased when subjects used arm supports while working. It is evident that the static load to shoulder muscles can be lowered significantly in keyboard work, when the forearms are at an angle of at least 100 degrees and by using arm supports. The most convienient and ergonomic working position can also be found individually be the method used here.

Objectives: The aim of the present study was to examine the effects of aerobic fitness on physiological stress responses experienced by teachers during working hours. Materials and Methods: Twenty six healthy female and male teachers aged 33-62 years, participated in the study. The ratings of perceived stress visual analogue scale (VAS), and the measurement of physiological responses (norepinephrine, epinephrine, cortisol, diastolic and systolic blood pressure, heart rate (HR) and trapezius muscle activity by electromyography (EMG) were determined. Predicted maximal oxygen uptake (VO 2 max) was measured using the submaximal bicycle ergometer test. The predicted VO 2 max was standardized for age using residuals of linear regression analyses. Results: Static EMG activity, HR and VAS were associated with aerobic fitness in teachers. Conclusions:The results suggest that a higher level of aerobic fitness may reduce muscle tension, HR and perceived work stress in teachers.