[Max test verify further clinical research for whether individualized symptom-limited cardiopulmonary exercise testing is the maximum extreme exercise].

To verify that the cardiopulmonary exercise testing (CPET) performed by clinical subjects is the maximum extreme exercise, we designed The Max test（Max）during clinical CPET. We used Max to verify the accuracy of the quantitative CPET evaluation result, and whether it is feasible and safe to use the specific value of a certain index as the standard for stopping CPET. Two hundred and sixteen cases from Fuwai Hospital were selected during June 2017 to January 2019,including 41 healthy person（control group） and 175with cardiovascular diseases（patient group）,The patients had a CPET peak RER ≤ 1.10, or the peak heart rate and peak blood pressure were basically non-responsive.The Max was first attempted in 60 subjects,and this study is further expanded . When the CPET ended, they had a 5-minute break, then the Max, during which, they cycled with a velocity of ≥ 60 r/min, at a constant intensity equivalent to to 130% of peak work,until exhausted.The difference and percentage difference between the peak heart rate and the peak oxygen uptake were calculated. ①If the percentage difference of heart rate and oxygen uptake are all less than -10%,then the Max is defined as failure,otherwise it is succesful. 2 If the percentage difference is between -10%~10%, then the Max is successful, which proved that the CPET is precise.③If the difference is ≥10%, the Max is successful, which proves that the CPET is non-extreme exercise. Patient group's Peak VO(L/min,ml/(min·kg)),anaerobic threshold (L/min,ml/(min·kg),%pred),Peak VO/HR(ml/beat, % pred),Peak RER,Peak SBP,Peak WR,peak heart rate,OUEP （ratio,%pred） were lower than those of the control group(P<0.05)．The VE/ VCO Slope （ratio,%pred）and Lowest VE/ VCO（ratio,%pred） were higher in the patient group than in the control group (P<0.05)．No adverse events occurred during the CPET and Max in all cases. Among the 216 cases,Max was successful in 198 cases(91.7%)．CPET was proved to be maximum extreme exercise for 182 cases,non-maximum extreme exercise for 16 cases,and failed in 18 cases(8.3%)． For CPET with a low peak RER and a maximum challenge,the Max can confirm the accuracy of the objective quantitative assessment of CPET. Max is safe and feasible,and that deserved further research and clinical application.