Cardiovascular and respiratory adjustments in normal volunteers during modified exercise tests in comparison to...

Sixteen normal, non-smoking first year medical students underwent four standard exercise tests, while cardiovascular (heart rate and blood pressure) and pulmonary (respiratory rate, tidal volume and oxygen consumption) adjustments were being monitored. Maximal exercise level for all tests were defined following the Jones scale. No variation was noted in respiratory rate among the four exercise tests. The cycle ergometry (CE), hand ergometry (HE), and treadmill (TM) exercise tests produced progressive increases of the various parameters as expected, although target maximal heart rates were not reached in most cases secondary to muscle fatigue. The step test (ST) approximated the physiological parameter changes noted in these three tests during the early stages of exercise, but levelled off after 3 minutes, probably due to lack of incremental load. The ST took the longest time to reach maximal level of exercise parameters, and recorded the lowest tidal volume increase. The same subjects underwent a modified step test (MST1) by adding 1 kg sandbags every 3 min to backpacks worn by the subjects, to provide incremental load. This modification provided a slight increase in the parameters measured, but still plateaued after 3 min. Another set of 18 normal, non-smoking medical students underwent bicycle ergometry and two other modified exercise tests. The modified step test two (MST2) was similar to our initial MST1, except that the sandbags added every 3 min were not fixed at 1 kg but were also incremental (1, 2, 3 and 4 kg). The other test (Ramp test or RT) required the subjects to walk up and down a ramp, which entailed not only the addition of incremental weights of sandbags every 3 min, but also increasing the elevation of the ramp at each stage. Data analysis showed that these two tests showed almost similar changes in cardiovascular and respiratory adjustments in the subjects, compared to the standard bicycle ergometry. These pilot studies showed that low-cost modified step tests may be utilized to approximate the expensive standard treadmill and bicycle exercise tests. More studies on larger populations have to be done to validate these results.