cardiac rehabilitation has been known to play a key role in the enhancement of exercise 
 ability , secondary prevention , and reduction in the mortality rate of patients with coronary 
 syndrome through comprehensive programs including exercise prescription , nutrition 
 counseling , drug therapy , and weight control1 , 2 . however , an improper rehabilitation program 
 may result in negative outcomes , especially in patients with cardiac problems . therefore , 
 the programs should be closely monitored and controlled to prevent undesirable side - effects . establishing the proper exercise intensity unique to a patient is one of the major steps in 
 designing an appropriate cardiac rehabilitation program . the exercise intensity 
 is established based on the maximal heart rate or maximal oxygen consumption 
 ( vo2peak ) obtained during an exercise stress test4 . although karvonen s formula ( 220  age ) , or the formula suggested 
 by aha ( american heart association ) { 206.9  ( 0.67  age ) } , are the most widely used formula 
 for establishing exercise intensity5 , 6 , they are not recommended for patients with 
 cardiovascular disorders . an exercise stress test is recommended to establish the maximal 
 heart rate , since medications such as beta blockers taken by patients are known to 
 considerably lower heart rates , not only at rest but also during exercise7 , 8 . the exercise stress test is usually conducted on a treadmill or ergometer to establish the 
 appropriate exercise intensity based on the percent heart rate reserve ( % hrr)4 . the exercise intensities obtained from 
 either treadmill or ergometer exercise have been interchangeably applied to prescribe 
 exercise programs for patients with acs . it was reported that vo2max obtained during tm was 6% to 25% higher 
 than vo2max obtained during ce , along with increased maximal heart rate9,10,11,12,13,14 . the maximum exercise capacity could not be achieved due to comparatively lower cardiac 
 outputs and early fatigue tendencies in the lower limbs during ce11 , 15 . in addition , 
 the maximal sbp measured during exercise stress tests was higher during ce than during 
 tm10 , 16 . when the exercise intensity established during a tm stress test is 
 applied to ce , despite the physiological differences reed17 reported a higher rate pressure production ( rpp ) during ce than 
 during tm , due to higher blood pressure responses with targeted heart rates established at 
 low- ( 40% ) and mid - intensity exercise ( 60% ) . angina pectoris was seen in patients with 
 stable angina who experienced chest pain during exercise at certain values of rpp18 , 19 . thus , when exercise is conducted on both a treadmill and an 
 ergometer with identical target heart rates , a higher exercise intensity may be achieved 
 during ce than during tm . moreover , the cardiac burden may be significantly increased at 
 higher exercise intensities , especially at 85% hrr or greater . in particular , rpp , which 
 measures the hemodynamic stress of the heart , may significantly increase to detriment of the 
 treatment effects and exercise performance , and further induce cardiovascular symptoms . 
 despite such significant differences in ce and tm , many guidelines for exercise prescription 
 do not clearly distinguish the characteristics and risks involved in the two exercise types . therefore , in order to elucidate the differences and risks involved in applying the 
 established exercise intensity to two different exercise types , this study calculated two 
 commonly used exercise intensities using a treadmill graded exercise test performed by 
 patients with acs . then , we applied the treadmill graded exercise test - derived exercise 
 intensities of 60% and 85% hrr to both tm and ce to assess the differences in the 
 hemodynamic responses , rate of perceived exertion ( rpe ) , and the number of cardiac events 
 between the two exercise types . the results may be used to improve exercise prescription 
 guidelines for patients with acs . the subjects of this study were patients who were hospitalized for acs , who received 
 percutaneous transluminal coronary angioplasty ( ptca ) and drug therapy , and participated in 
 a hospital - based cardiac rehabilitation program from may 2009 to april 2011 . the subjects 
 were recruited on a voluntary basis . after explaining the purpose and procedure of the 
 study , the subjects volunteered and gave their written consent before participating in the 
 study . the study design and procedures were approved by the institutional review board ( irb ) 
 of inje university sanggae baik hospital . the study was performed according to the 
 guidelines set by the ethics committee20 . the patients with severe arrhythmia , heart failure with 40% or less ejection fraction in the 
 left ventricle , exercise - induced high blood pressure , an interrupted exercise stress test 
 due to abnormal cardiovascular response , changes in administered drugs during the study 
 period , or chronic obstructive pulmonary or musculoskeletal disease contraindications to the 
 exercise stress test were excluded from this study . although no premature termination was 
 observed during the exercise stress test , 16 out of 118 patients were excluded from the 
 study due to reasons such as difficulty adapting to ce or the prescribed exercise loads . of 
 the 102 patients who completed this study , 38 patients were diagnosed as having unstable 
 angina ( 37.3% ) and 64 were diagnosed as having acute myocardial infarction ( 62.7% ) . the 
 patient characteristics such as age , sex , height , weight , body mass index ( bmi ) , 
 complications , administered drugs , heart rate ( hr ) , blood pressure ( bp ) , rpp , and 
 vo2max are described in table 
 1table 1 . demographic characteristics of the subjects ( n=102)variablesmeansd / frequencyage ( y)56.69.7 ( m ) / 57.83.6 ( f)sex ( male / female)93 ( 91.2% ) / 9 ( 8.8%)height ( cm)167.0.6.0 ( m ) / 154.69.3 ( f)weight ( kg)69.68.9 ( m ) / 61.711.3 ( f)bmi ( kg / m)25.03.1 ( m ) / 25.73.1 ( f)diseaseua38 ( 37.3%)mi64 ( 62.7%)complicationshypertension56 ( 54.9%)diabetes mellitus24 ( 23.5%)dyslipidemia24 ( 24.5%)drugsaspirin102 ( 100%)plavix98 ( 96.1%)beta - blocker37 ( 36.3%)ccb9 ( 8.8%)carvedilol26 ( 25.5%)acei51 ( 50%)arb10 ( 9.8%)nitrate63 ( 61.8%)diuretics10 ( 9.8%)statin95 ( 93.1%)hrrest ( beat / min)72.512.6sbprest ( mm hg)117.316.9dbprest ( mm hg)78.510.0rpprest8486.81784.7 vo2max ( o2 ml / kg / min)28.36.9hr max ( beat / min)138.218.4sbp max ( mm hg)174.928.4dbp max ( mm hg)78.510.0rpp max24359.4 5771.5values are meansd , bmi : body mass index , mi : myocardial infarction , ccb : calcium 
 channel blocker , acei : angiotensin converting enzyme inhibitor , arb : angiotensin ii 
 receptor blocker , hr : heart rate , sbp : systolic blood pressure , dbp : diastolic blood 
 pressure , rpp : rate pressure product . values are meansd , bmi : body mass index , mi : myocardial infarction , ccb : calcium 
 channel blocker , acei : angiotensin converting enzyme inhibitor , arb : angiotensin ii 
 receptor blocker , hr : heart rate , sbp : systolic blood pressure , dbp : diastolic blood 
 pressure , rpp : rate pressure product symptom - limited graded exercise tests ( gxt ) were conducted with a modified bruce protocol 
 within a week of discharge . the tests were conducted to determine the appropriate exercise 
 intensities prior to cardiac rehabilitation exercise on a treadmill and cycle ergometer . peak oxygen consumption ( vo2peak ) and the highest value of vo2 were 
 measured during the gxt . a 12-channel real - time 
 electrocardiograph ( q4500 , quinton instrument co. , boston , usa ) , a gas analyzer ( qmc 
 ( quinton metabolic cart ) , quinton instrument co. , boston , usa ) , an automated blood pressure 
 and pulsation measurement device ( model 412 , quinton instrument co. , boston , usa ) , and a 
 treadmill ( medtrack st 55 , quinton instrument co. , boston , usa ) were used for the exercise 
 stress tests . heart rate ( hr ) , blood pressure ( bp ) , and vo2 at rest and during 
 maximal exercise were recorded . the borg scale ( 620 ) was also used to measure the rate of 
 perceived exertion ( rpe ) . s 
 formula,{(maximal heart rate  resting heart rate  % intensity ) + resting heart rate } based 
 on the results obtained during the exercise stress test6 . the cardiac rehabilitation program was composed of 10 minutes warm up ( stretching ) , 24 
 minutes of main exercise ( treadmill or cycle ergometer ) , and 10 minutes of cool down ( 3 
 minutes of slow walking and stretching)22 . the main exercise was divided into two 12-minute exercise bouts 
 either on a treadmill ( quinton med - track sr 60 , quinton instrument co. , boston , usa ) or a 
 fixed cycle ergometer ( quinton corival 400 , quinton instrument co. , boston , usa ) . the 
 participants took a three - minute rest by calmly walking on a flat floor between the two 
 12-minute exercise bouts . the exercise sessions were conducted every other day for two 
 weeks , in a total of six sessions . the cardiac rehabilitation exercise program was conducted alternatively on a treadmill and 
 a cycle ergometer with a gradual increase in the exercise intensity . on the first , third , 
 and fifth sessions , the treadmill exercise intensity was gradually increased to 60% hrr , 70% 
 hrr , and 85% hrr , respectively . on the second , fourth , and sixth sessions , the cycle 
 ergometer intensity was gradually increased to 60% hrr , 70% hrr , and 85% hrr , 
 respectively . hr , sbp , dbp , rpp , rpe , and cardiac events were assessed two minutes prior to the end of 
 all the first exercise bouts . an ecg telemetry system ( quinton instrument co. , boston , usa ) 
 and a mercury blood pressure unit with a stethoscope were used to measure hr and bp at the 
 chest height of the patients . the devices were also used to monitor for clinical signs of 
 myocardial ischemia , or arrhythmia . rpe was 
 measured on the borg scale23 , and 
 possible chest pain was expressed using an angina pectoris scale24 . the measurements obtained during tm and ce at 60% and 85% 
 hrr were used for comparison . the measurements were performed by the same investigators to 
 maintain the measurement accuracy and impartiality . flow chart of the study procedure descriptive statistics were used to calculate the patients characteristics . the 
 measurements were evaluated using one - way repeated - measures anova with the exercise 
 intensities of 60% hrr , and 85% hrr during ce and tm as the independent variables . the measurement 
 differences between patients without cardiac event during ce ( ce - ne ) and tm ( tm - ne ) and in 
 patients with cardiac events during ce ( ce - e ) were analyzed using one - way anova . after 
 determining the significance of the difference by anova , a post - hoc multiple comparison was 
 performed using the scheffe test . fisher s exact test was performed to assess the 
 significance of differences between the proportions of the two exercise types . all statistical analyses were performed 
 using spss for windows , version 14 ( spss inc . , medium and high exercise intensities of 60% and 85% hrr were calculated for the cardiac 
 rehabilitation exercise based on the results obtained during gxt using karvonen s formula . the hemodynamic 
 responses , rpe , and cardiac events were measured to determine the differences between the 
 exercise types and to evaluate the significance of the differences in patients with acs . hemodynamic responses ( n=102 ) to treadmill and cycle ergometer exercise at 
 60%hrr and 85%hrr60%hrr - tm60%hrr - ce85%hrr - tm85%hrr - cehr ( beats / min)111.913.0 110.713.8127.416.4128.214.4sbpmax ( mm hg)135.218.8 155.822.6151.620.0177.123.6%sbpmax78.210.0%89.911.3%87.710.9%102.212.0%dbpmax ( mm hg)77.18.9 83.711.579.28.988.711.3%dbpmax101.716.3%110.118.1%104.415.8%116.817.8%rppmax152273187175163641195744014228534782%rppmax63.48.6%73.09.5%81.410.1%95.011.1%rpemax11.11.512.41.313.01.215.31.2hr : heart rate , sbp : systolic blood pressure ( mmhg ) , dbp : diastolic blood pressure 
 ( mmhg ) , rpp : rate pressure product , rpe : rate of perceived exertion . these values were obtained by dividing 
 the maximal sbp , dbp , and rpp values obtained at 60% hrr and 85% hrr during ce and tm 
 by sbpmax ( 17528 mmhg ) , dbpmax ( 7713 mmhg ) , and 
 rppmax ( 243595771 ) obtained during treadmill gxt , respectively , and 
 multiplying each result by 100%.*=significantly different from the previous trial , p < 0.001 shows the maximal hemodynamic responses of hr , sbp , dbp , as well as rpp and 
 rpe at the 60% and 85% exercise intensities during tm and ce . the maximal sbp , dbp , and rpp 
 values were divided by the maximal sbp , dbp , and rpp values obtained during treadmill gxt 
 and multiplied by 100% to obtain percentages for comparison . hr at the exercise intensities 
 of 60% and 85% were identical ( tm vs. ce = 111.913.0 bpm vs. 110.713.8 bpm at 60% hrr ; tm 
 vs. ce = 127.416.4 bpm vs. 128.214.4 bpm at 85% hrr . hr : heart rate , sbp : systolic blood pressure ( mmhg ) , dbp : diastolic blood pressure 
 ( mmhg ) , rpp : rate pressure product , rpe : rate of perceived exertion . these values were obtained by dividing 
 the maximal sbp , dbp , and rpp values obtained at 60% hrr and 85% hrr during ce and tm 
 by sbpmax ( 17528 mmhg ) , dbpmax ( 7713 mmhg ) , and 
 rppmax ( 243595771 ) obtained during treadmill gxt , respectively , and 
 multiplying each result by 100% . * = significantly different from the previous trial , p < 0.001 for sbp expressed as a percentage of maximal sbp , % sbpmax ( 89.911.3% ) of 60% 
 hrr during ce was significantly higher than % sbpmax ( 78.210.0% ) of 60% hrr during tm . % sbpmax ( 102.212.0% ) of 85% hrr during ce was also significantly higher than % sbpmax 
 ( 87.710.9% ) of 85% hrr during tm ( p < 0.001 ) , and % sbpmax of 85% hrr during 
 ce showed the highest value . % rppmax 
 ( 73.09.5% ) of 60% hrr during ce was significantly higher than % rppmax ( 63.48.6% ) of 60% 
 hrr during tm , and % rppmax ( 95.011.1% ) of 85% hrr during ce was also significantly higher 
 than % rppmax ( 81.410.1% ) of 85% hrr during tm ( p < 0.001 ) . in addition , all measurements of dbp and rpe at the exercise intensities of 60% hrr and 85% 
 hrr were significantly higher during ce than during tm ( p < 0.001 ) . in order to confirm the increased risk of ce , the patients were continuously monitored and 
 recorded for cardiac events during all the exercise sessions ( table 3table 3 . blood pressure and rpe responses of the patients with and without cardiac - events 
 at the two different exercise intensities cycle ergometer and treadmill 
 exercise60%hrr85%hrrtm - ne ( n=101)ce - ne ( n=72)ce - e ( n=29)tm ( n=101)ce - ne ( n=72)ce - e ( n=29)%sbpmax78.09.888.310.793.411.587.610.999.29.9110.413.7%rppmax63.38.471.48.876.19.981.410.192.19.1101.912.7rpemax11.01.412.31.212.71.613.01.114.60.816.90.5tm - ne = patients without cardiac event during treadmill exercise , ce - ne = patients 
 without cardiac event during cycle ergometer exercise , ce - e = patients with cardiac 
 events during cycle ergometer exercise . the tm - e group was omitted from the comparison 
 since only one patient showed a cardiac event during treadmill exercise . sbp : systolic 
 blood pressure , rpp : rate pressure product , rpe : rate of perceived exertion . % sbpmax and % rppmax were calculated by dividing the maximal 
 sbp and rpp obtained at 60%hrr and 85%hrr during ce and tm by sbpmax 
 ( 17528 mmhg ) and rppmax ( 243595771 ) obtained during treadmill gxt , 
 respectively , and multiplying each result by 100% .  = significantly different from 
 60%hrr - tm , p < 0.05 , = significantly different from 85%hrr - tm , p < 0.05 , * = 
 significantly different from 85%hrr - ce - ne , p < 0.05 . ) . of the 102 patients , 29 patients ( 28.4% of the patients ; ce - e : patients with 
 cardiac events during cycle ergometer exercise ) showed cardiac events at 85% hrr during ce . % sbpmax and % rppmax of 60% hrr and 85% hrr during tm for the 29 
 patients with cardiac events and the 72 patients without cardiac events were calculated for 
 comparison ( table 3 ) . significantly higher 
 maximal % sbp , % rpp , and rpe were shown at 60% hrr and 85% hrr during ce than during tm in 
 the patients with ( ce - e ) compared to those without ( ce - ne ) cardiac events . % sbpmax and % rppmax showed non - significant differences in both ce - e 
 and ce - ne at 60% hrr during ce . however , the patients without cardiac event ( ce - ne ) at 85% 
 hrr during ce had significantly higher % sbpmax and % rppmax 
 ( p<0.001 ) . furthermore , % sbpmax and % rppmax of ce - e were 
 110.413.7% , and 101.912.7% , respectively , exceeding the maximal sbp and rpp obtained in 
 the treadmill gxt . although rpemax for ce - ne ( 14.60.8 ) was significantly greater 
 than rpemax of tm ( 13.01.1 ) , rpemax for ce - e was much greater 
 ( 16.90.5 ) with a difficulty level of  very very difficult tm - ne = patients without cardiac event during treadmill exercise , ce - ne = patients 
 without cardiac event during cycle ergometer exercise , ce - e = patients with cardiac 
 events during cycle ergometer exercise . the tm - e group was omitted from the comparison 
 since only one patient showed a cardiac event during treadmill exercise . sbp : systolic 
 blood pressure , rpp : rate pressure product , rpe : rate of perceived exertion . % sbpmax and % rppmax were calculated by dividing the maximal 
 sbp and rpp obtained at 60%hrr and 85%hrr during ce and tm by sbpmax 
 ( 17528 mmhg ) and rppmax ( 243595771 ) obtained during treadmill gxt , 
 respectively , and multiplying each result by 100% .  = significantly different from 
 60%hrr - tm , p < 0.05 , = significantly different from 85%hrr - tm , p < 0.05 , * = 
 significantly different from 85%hrr - ce - ne , p < 0.05 total cardiac events and rpe responses ( n=102 ) at the different exercise 
 intensities of the different exercise types60% hrr60% hrr85% hrr85% hrrtmcetmcecardiac eventschest pain ( 2 ) + rpe ( 17)0011chest pain ( 2 ) + rpe ( 15)0003intermittent pvc + rpe ( 17)0001bigeminy pvc + rpe ( 17)0001af + rpe ( 17)0001st depression without chest pain0001total cardiac events0018rpe responserpe 1700021chest pain scale ( 2 ) : mild chest pain . rpe : rate of perceived exertion , pvc : 
 premature ventricle contraction , af : atrial fibrillation , st segment depression : 1  mm 
 ( horizontal ) , * = significantly different , p < 0.01 shows the number of patients who were interrupted during exercise due to the 
 occurrence of cardiac events . one patient at 85% hrr during tm and one patient at 85% hrr 
 during ce complained of rpe of 17 ( very hard ) with some chest pain . three patients at 85% 
 hrr during ce complained of rpe of 15 ( hard ) with some chest pain . at 85% hrr during ce , one 
 patient complained of rpe of 17 with intermittent pvcs ( premature ventricular contractions ) , 
 one patient complained of rpe of 17 with bigeminy pvc , one patient complained of rpe of 17 
 with atrial fibrillation , and one patient showed st segment depression ( 1  mm , horizontal ) . chest pain or arrhythmia occurred between 8 to 12 minutes after the initiation of the first 
 exercise session . twenty - one patients complained of rpe of 17 without an event at the 85% 
 hrr during ce . all the relative hemodynamic values of the two exercise types at 85%hrr 
 showed significant differences ( p<0.01 ) . cardiac events were not observed at 70% hrr 
 during tm , but 4 patients terminated the exercise sessions during ce . rpe : rate of perceived exertion , pvc : 
 premature ventricle contraction , af : atrial fibrillation , st segment depression : 1  mm 
 ( horizontal ) , * = significantly different , p < 0.01 the hemodynamic responses , rpe , and cardiac events during two common exercise types 
 conducted at 60% and 85% hrr were assessed in patients with acs . although early 
 rehabilitation exercise is helpful for improving health status , the exercise mode should be 
 carefully monitored . patient - specific exercise intensity has been traditionally obtained through a treadmill 
 exercise graded test for both treadmill and cycle ergometer exercises . rpp was significantly higher during ce than during tm at intensities of 60% hrr and 85% hrr 
 due to higher blood pressure . rpp measured during 60% hrr - ce was close to 90% of the maximal 
 rpp , and rpp during 85% hrr - ce exceeded the maximal rpp ( 102.212.0% ) . various cardiac 
 events were induced when rpp exceeded the maximal rpp during 85% hrr - ce . there have been 
 many studies of the physiological characteristics of the exercise stress test done on a 
 treadmill and cycle ergometer . the major differences in characteristics of ce , compared to 
 tm , have been reported to be increased maximal heart rate and vo2max9,10,11,12,13,14 . moreover , higher blood pressures were also induced during ce than during tm6 , 16 . 
 because of these physiological differences , application of exercise intensity based on the 
 maximal heart rates obtained from either exercise type may expose cardiac patients to risk 
 of various clinical problems . in this study , both rpp and rpe were significantly higher during ce than during tm at 
 60%hrr and 85%hrr due to elevation of blood pressure . in addition , rpp during 60% hrr - ce was 
 close to 90% of the maximal rpp , and rpp during 85%hrr - ce exceeded the maximal rpp . this 
 significant increase in rpp was also caused by elevated blood pressure during ce . although 
 ce is mostly aerobic exercise , it is a combined form of exercise with some anaerobic factors 
 in it19 . the sbp of professional cyclists may increase to 200 mmhg during a maximal ce stress 
 test19 , and their heart rates can be 
 maintained close to the maximal hr for the duration of a race24 . the average bp of endurance runners has been reported to be around 
 175/69 mmhg during exercise25 , while the 
 average heart rate of resistance exercise athletes has been reported to be between 102 and 
 170 bpm , with maximal bp of 480/350 mmhg26 . it was reported that the athletes specializing in cycling or 
 rowing not only have bigger internal cardiac chambers , but have thicker myocardial walls due 
 to the differences in hemodynamic responses compared to other athletes19 . moreover , endurance runners generally have larger 
 internal cardiac diameters , and resistance exercise athletes have thicker cardiac chamber 
 walls . generally , ce requires active performance in resistive pedaling with a greater range of 
 motion and higher angle , while tm is performed under a condition which is relatively less 
 active , and has a fixed grade and speed . for these reasons , increase in blood pressure 
 during ce may be caused by greater resistance to blood flow in the exercising muscles27 , and larger tension within the lower limb 
 muscles due to the increase in exercise intensity28 . reed reported that both the systolic and diastolic phases of females with sedentary 
 lifestyles were higher during ce than during tm at exercise intensities of 40% hrr and 60% 
 hrr17 . these results indicate that rpp 
 can be increase more during ce than during tm at identical exercise intensities . rpp can be easily measured by multiplying the mean heart rate by the systolic blood 
 pressure obtained during an exercise stress test29 , 
 30 . rpp is a reliable indicator of 
 myocardial perfusion demand not only for patients with coronary arterial diseases , but also 
 for healthy individuals18 . many patients 
 with chronic stable angina tend to experience chest pain at a certain rpp18 , 31 . furthermore , an exercise which 
 increases rpp in patients with aortic aneurysm may lead to aneurysm rupture33 . the beta blockers used to decrease the 
 ischemic threshold , or prevent arrhythmia or aortic aneurysm rupture are also used to reduce 
 rpp32 , 33 . in this study , the 102 subjects who completed the cardiac rehabilitation exercise program 
 on the cycle ergometer exceeded maximal rpp during 85% hrr - ce . in terms of cardiac events , ce induced 8 cases of cardiac events which included light chest pain ( 4 cases ) , arrhythmia 
 ( 3 cases ) compared to just one case of chest pain during tm . twenty - one patients complained 
 of strenuous exertion with pre 17 or over during cycle ergometer exercise at 85%hrr ( table 4 ) . a number of patients complained during performance of ce and terminated 
 exercise ( 70% hrr exercise was excluded ) . although cardiac events were not observed , 16 out 
 of 118 patients who were excluded from the study groups complained of leg pain or 
 interrupted exercise sessions due to excessive fatigue during ce11 , 15 . therefore , 
 additional recommendations for cardiac rehabilitation guidelines may be needed , explaining 
 the differences in exercise intensity between tm and ce along with selective guidelines for 
 patients with cardiovascular diseases , aneurysm , or exercise - induced high blood 
 pressure . first , it was difficult to reach target heart rates 
 within the given time of 12 minutes by control of the exercise intensity . the pedaling speed 
 as well as the power ( watts ) was adjusted for each patient in consideration of his / her 
 physical condition . in addition , it was difficult to balance or adjust the angle of incline 
 as well as the speed on the treadmill during tm . differences in adjustments may have 
 resulted in minor differences in exercise intensities among patients .
[ purpose ] this study investigated the effects of mid , and high exercise intensities on 
 hemodynamic responses and cardiac events during two exercise types of treadmill exercise 
 ( tm ) and cycle ergometer exercises ( ce ) in patients with acute coronary syndrome ( acs ) . 
 [ subjects ] patients who had percutaneous coronary intervention ( pci ) for acs and were 
 participating in cardiac rehabilitation program were included . 
 [ methods ] the patients were 
 assessed for hemodynamic responses , cardiac events , and rate of perceived exertion ( rpe ) 
 with target heart rates of 60% and 85% heart rate reserve ( hrr ) during tm and ce . 
 [ results ] maximum systolic blood pressure ( sbp ) , diastolic blood pressure ( dbp ) , rpe , and 
 rate pressure product ( rpp ) measured during ce were significantly higher than their values 
 in tm at the same exercise intensities . the highest sbp was shown at 85% hrr during ce . 
 sbpmax to sbpmax ratios obtained during the graded exercise test 
 ( gxt ) showed that all % sbpmax were significantly greater in ce than in tm at 
 the same exercise intensities . 
 out of 102 patients , cardiac events occurred in 8 at 85% 
 hrr during ce , and 1 at 85% hrr during tm . 
 patients with cardiac events ( ce - e ) had 
 significantly higher % sbp , % rpp , and rpe at 85% hrr than those without events ( ce - ne ) 
 during ce . 
 [ conclusion ] prescribing exercise based on the intensity obtained in a 
 treadmill gxt may expose patients to cardiovascular complications such as higher rpp , 
 higher exercise intensity , and cardiac events during ce .