Differences in cardiorespiratory responses during and after arm crank and cycle exercise.

The differences in cardiorespiratory responses were examined during and after intermittent progressive maximal arm-crank and cycle exercise. Arm-crank exercise was performed in a standing position using no torso restraints to maximize the amount of active skeletal muscle mass. Recovery was followed for 16 min. In the tests a variety of ventilatory gas exchange variables, heart rate, the blood pressure, and the arm venous blood lactate concentration were measured in 21 untrained healthy men aged 24-45 years. At equal submaximal external workloads for arm cranking and cycling (50 and 100 W) the respiratory frequency, tidal volume, pulmonary ventilation, oxygen uptake, carbon dioxide output, the respiratory exchange ratio, heart rate, the arm venous blood lactate concentration, and the ventilatory equivalent for oxygen were higher (P less than 0.001) during arm cranking than cycling. The maximal workload for arm cranking was 44% lower than that for cycling (155 +/- 37 vs 277 +/- 39 W, P less than 0.001) associated with significantly (P less than 0.001) lower maximal tidal volume (-20%), oxygen uptake (-22%), carbon dioxide output (-28%), systolic blood pressure (-17%) and oxygen pulse (-22%) but a higher ventilatory equivalent for carbon dioxide (+22%) and arm venous blood lactate concentration (+37%). However, these responses after arm-crank and cycle exercises behaved almost similarly during recovery. The high cardiorespiratory stress induced by arm work should be taken into account when the work stress and work-rest regimens in actual manual tasks are assessed, and when arm work is used for clinical testing, and in physiotherapy particularly for patients with heart or pulmonary diseases.

Effect of changes in Pco2 on intraocular tension.

Elevated levels of inspired CO2 and blood Pco2 resulted in moderate elevation of IOT. A marked rapid decrease in IOT to a level less than baseline value was noted when inspired CO2 was suddenly decreased to ambient levels. Decrease in IOT was more pronounced than the decrease in Pco2 and increase in blood pH. Changes in IOT appeared related to the rate of change of Pco2 rather than the actual level of Pco2. Increased ventilatory excursions with constant inspired CO2 levels did not cause any elevation of IOT, but a minimal compensatory drop in IOT below resting values occurred when increased ventilatory excursions were discontinued. It is postulated that the changes in IOT noted are the result of sudden changes in aqueous production or ocular blood volume.

Standardized aerobic and anaerobic exercise: differential effects on intraocular tension, blood pH, and lactate.

The effects of standardized aerobic and anaerobic exercise intensities on intraocular tension, blood lactate, and pH were studied. Intraocular tension decreased rapidly at all exercise intensities. The absolute lowest level of intraocular tension reached with aerobic and anaerobic exercise levels varied by only 1.5 mm. Hg and this difference was not statistically significant. Blood lactate and pH changes correlated with intraocular tension changes at anaerobic exercise levels, but not at aerobic exercise levels. These findings associated with aerobic exercise have not been previously reported. It is suggested that parameters other than the decrease in blood pH and the increase in blood lactate are responsible for most of the decrease in intraocular tension associated with dynamic exercise.

The validity of three indirect methods of measuring oxygen uptake and physical fitness.

The validity coefficient of Astrand's and von Döbeln's indirect methods for estimating maximal oxygen uptake and physical fitness was calculated using 48 Finnish men between the ages of 30 and 40 years. The criterion for the former was the directly measured maximal oxygen uptake, and for the latter Ismail's test battery No. 3 was used. Similarly the validity coefficient of the serum lactate concentration in submaximal work was determined. Also an attempt was made to study the effect of adding the lactate concentration to the prediction functions of Astrand and von Döbeln. It was found that the validity of these two methods, as expressed by the correlation coefficient, was higher when compared with the Ismail test battery than when compared with the directly measured maximal oxygen uptake. The coefficient values between the predictions and Ismail's test battery No. 3 were .844 for Astrand and .793 for von Döbeln. When the serum lactate was included in von Dibeln's formula, the prediction of the Ismail measure resulted in a significant improvement, at a p level of <.05, over the value obtained by von Döbeln's formula alone.