Graded exercise testing for spaceflight.

We developed and validated a graded exercise protocol suitable for operational use on space station. The new treadmill protocol has three level-grade stages (3-min each) at 70, 80, and 90% of estimated V O2peak . The protocol maintains the third stage speed while grade increases each minute to produce work rates equivalent to 100, 107, and 115% of the estimated V O2peak . We compared the new protocols's peak and submaximal responses to those observed during a NASA graded exercise test. All mean protocol differences, including peak work rate (−1.8%), V O2peak (−6.4%), HR peak (−2.4%), and V Epeak (−9.7%), were not significantly different from the expected measurement errors. We observed similar results for indices (the oxygen uptake at a HR of 150 and the HR's at 70, 80, and 90% of V O2peak ) of the submaximal HR-V O2 relationship. The new protocol is an acceptable graded exercice test for periodic operational fitness tests