Dysrhythmia comparison in apparently healthy males during and after treadmill and acceleration stress testing

Maximal treadmill exercise stress testing and centrifuge +Gz-acceleration stress testing are both known to be dysrhythmogenic. A comparison of the effects of these two stresses on 60 healthy men was performed. The 60 individuals were divided into three groups of 20 each. One group was made up of healthy volunteer members from the United States Air Force School of Aerospace Medicine acceleration stress panel. The other two groups were asymptomatic USAF aircrewmen undergoing aeromedical evaluation for newly discovered dysrhythmias (dysrhythmia group) and for other aeromedical abnormalities (nondysrhythmia group). The effect of these two stresses on the poststress cardiac rate and rhythm were also evaluated by means of 24-hour Holter monitoring. Both stresses were observed to induce dysrhythmias with approximately the same frequency in the two patient groups; but, with the panel members who experienced higher +Gz stress, the centrifuge stress induced more dysrhythmias than did treadmill exercise stress. The stress-induced changes were limited to the period of stress and did not significantly affect cardiac rate or rhythm in the poststress 24-hour period. Certain dysrhythmias were more commonly associated with centrifuge stress. Centrifuge acceleration stress testing apparently is as safe as maximal treadmill exercise testing. For USAF high-performance fighter pilots who are routinely exposed to repeated high sustained +Gz stress during aerial combat, it is imperative to assure that they are not predisposed to +Gz-induced dysrhythmias which could cause sudden inflight incapacitation. Centrifuge stress testing is therefore a valuable tool in the aeromedical evaluation of these aircrewmen.