in the development of nutritional and physical activity interventions , understanding 
 resting metabolic rate ( rmr ) is important to identify the absolute daily energy requirement 
 and achieve desirable energy consumption1 . 

rmr provides energy necessary to maintain body functions at rest and accounts for 6080% of 
 total energy expenditure2 .
an imbalance of 
 energy intake and expenditure leads to weight gain or loss in the long term3 .
physical exercise improves health by improving cardiorespiratory fitness , body composition , 
 and psychosocial well - being .
in addition , physical exercise is an important tool in the 
 prevention and treatment of obesity4,5,6 . 

physical exercise improves body composition and metabolic activity , thereby reducing excess 
 weight and related comorbidities7,8,9,10,11 .
vo2max measures the maximal oxygen consumption during exercise to the point of 
 exhaustion of physical strength and is one of the best methods of predicting 
 cardiorespiratory endurance and aerobic preparation .
the amount of energy needed by 
 individuals is associated with body mass , and vo2max is associated with body 
 weight .
regular aerobic physical activities increase vo2max and indirectly reduce 
 the effects of many diseases12 .
the 
 respiratory system plays an important role in providing the energy required by different 
 body systems for metabolism .
therefore , the respiratory system is greatly affected by short- 
 and long - term exercise . owing to its important role in physical activities , the respiratory 
 system is studied by many researchers13 . 
 the level of cardiorespiratory fitness varies with the condition of the respiratory , 
 cardiovascular , and musculoskeletal systems , and its evaluation is important because of its 
 relationship to health and wellness .
poor cardiorespiratory fitness increases the rate of 
 all causes of premature death , and especially that due to cardiovascular diseases . 

improvement in cardiorespiratory fitness is associated with reduced premature death rates 
 due to all causes14 , 15 .
many previous studies examined changes in rmr and vo2max after intervention with 
 defined exercise for a certain period of time16,17,18,19 .
in addition , studies have compared rmr 
 and vo2max for habitual physical activities , regularly performed types of 
 exercise , and different fitness levels .
gilliat - wimbery et al.20 studied differences in rmr and vo2max between 
 the two groups with different habitual physical activities , and toth et al.21 studied differences in rmr and 
 vo2max among three groups with different types of regularly performed exercise . 

in addition , mccargar et al . compared the levels of vo2max for different fitness 
 levels22 .
however , studies that 
 subdivide individuals by amount of exercise at normal times are lacking .
therefore , the present study intended to examine the effects of individual weekly exercise 
 time on rmr and vo2max , which are important components of individual health 
 indexes .
this study can be helpful in preventing and treating health problems using 
 subdivided exercise programs customized for individuals .
thirty healthy adult male and female subjects between the ages of 20 and 60 who satisfied 
 the following selection criteria were studied : without cardiopulmonary , metabolic , or 
 musculoskeletal disorders ; not pregnant ; not taking any mood - altering medications or other 
 drugs , including anti - inflammatory drugs , antihistamines , pain medications , antidepressants , 
 or beta - blockers23 ; not athletes ; had not 
 participated in similar studies ; understood the purpose of the study , and agreed to 
 participate .
all participants were informed about the potential risks and experimental 
 design and provided informed consent for participation , with the knowledge that they could 
 withdraw at any time .
the general 
 characteristics of the study subjects are shown in table 1table 1.general characteristics of the study subjectsgroup a(n=25)meansdgroup b(n=15)meansdgroup c(n=17)meansdgender ( male / female)12/136/97/10age ( years)41.213.140.212.442.312.7height ( cm)164.17.2162.98.0165.76.9weight ( kg)64.112.162.711.763.414.2values are mean sd .
the 
 frequency of walking at moderate or high intensity24 of exercise awareness ( 12 or more on the borg scale ) at normal 
 times , and the duration of exercise per session were surveyed .
the subjects were divided 
 into group a , who did not perform any walking exercise at all per week , group b , who 
 performed walking for less than 200 minutes per week , and group c , who performed walking for 
 200 minutes or more per week . a body composition analyzer ( inbody720 , biospace , south korea ) was used , and general 
 characteristics including age , height , weight , body mass index ( bmi ) , fat free mass ( ffm ) , 
 muscle mass , skeletal muscle mass , and obesity indexes such as visceral fat area ( vfa ) and 
 waist - hip ratio ( whr ) were recorded .
rmr was measured using a respiratory gas analyzer ( quark b2 , cosmed , italy ) .
all subjects 
 were prohibited from performing exercise for four hours before measurement of rmr between 
 10:00 am and 4:00 pm .
rmr was measured in supine subjects for 31 minutes after a five - minute 
 rest25 .
graded exercise tests were conducted using a 12-channel electrocardiogram scanner ( case 
 6.0 , ge , usa ) , respiratory gas analyzer ( quark b2 , cosmed , italy ) , and automatic blood 
 pressure ( bp ) and pulse measuring instrument ( tango , suntech medical , usa ) on a treadmill 
 ( t2100 , ge , usa ) under supervision by a researcher and safety guard .
subjects were instructed to stop exercise in one or more of the 
 following situations : heart rate ( hr ) did not increase with exercise intensity ; respiratory 
 exchange ratio was 1.15 or higher ; exercise awareness ( borg scale ) was 17 or higher ; hr was 
 90% or higher than age - predicted maximum ( 220 minusage ) ; or o2 uptake did not 
 increase with exercise intensity27 . along with vo2max ,
exercise ability indexes were measured , including hemodynamic 
 indexes such as bp and hr at the time of maximum exercise , the ventilatory equivalent for 
 o2 ( ve / vo2 ) , the ventilatory equivalent for carbon dioxide 
 ( ve / vco2 ) , and the physiological dead space / tidal volume ratio ( vd / vt ) . in 
 addition , respiratory indexes , such as breathing reserve ( br ) , and metabolic indexes , such 
 as anaerobic threshold ( at ) and maximum o2 pulse , were measured . to analyze
the data in this study , statistics program spss 18.0 for windows was used . for 
 general characteristics of this study , frequency analysis , means , and standard deviations 
 were calculated . to compare differences between the groups in headache and stiffness 
 changes , one - way analysis of variance
in addition , to examine differences in headache and stiffness before and after 
 each intervention , a paired t - test was conducted .
the results of graded exercise tests of the three groups are shown in table 2table 2.graded exercise testvariablesgroup agroup bgroup cmax .
bp ( mmhg)83.021.987.014.191.216.2ve / vo2 ( l / min)46.87.545.77.045.66.4ve / vco2 ( l / min)37.65.139.05.436.15.0vd ( ml)323.5107.7376.7107.7390.0118.0vd / vt0.2140.0290.2250.0430.2100.037br ( max .
ve / mvv , % ) 88.03.587.82.688.63.5vo2max ( ml / min)1,735.4467.52,113.0443.62,445.1616.6at ( % ) 61.921.082.629.992.438.6o2pulse ( ml / beat)13.04.415.97.322.220.9values are meansd , * p<0.05 , group a did not perform any walking 
 exercise at all per week , group b performed walking for less than 200 
 minutes per week , group c performed walking for 200 minutes or more per 
 week , max .
bp : maximum diastolic blood pressure , ve / vo2 : ve for o2 , 
 ve / vco2 : ve for co2 , vd : physiological dead space , vd / vt : 
 physiological dead space / tidal volume ratio , br : breathing reverse ( maximum exercise 
 ventilation / maximal voluntary ventilation ) , vo2max : maximal oxygen uptake , 
 at : anaerobic threshold ( % , o2 uptake at at / peak o2 uptake ) , 
 o2 pulse : peak o2 pulse ( vo2/hr ) .
significant differences in vo2max and at were found among the 
 three groups ( p<0.05 ) .
however , the remaining indexes did not show any statistically 
 significant differences ( p>0.05 ) .
the results for the rmr and obesity indexes of the 
 three groups are shown in table 3table 3.results for rmr and obesity indexesvariablesgroup agroup bgroup crmr ( l / min)1,083.3267.81,314394.01,420.2244.0bmi ( kg / m)22.32.123.182.924.62.9ffm ( kg)45.99.349.88.853.69.7muscle mass ( kg)43.38.947.08.550.69.3skeletal muscle mass ( kg)25.35.827.65.430.06.0vfa ( cm)75.436.793.044.489.626.8whr0.80.00.80.00.90.0values are meansd , * p<0.05 , group a did not perform any walking 
 exercise at all per week , group b performed walking for less than 200 
 minutes per week , group c performed walking for 200 minutes or more per 
 week , rmr : resting metabolic rate , bmi : body mass index , ffm : fat free mass , vfa : 
 visceral fat area , whr : waist - hip ratio .
values are meansd , * p<0.05 , group a did not perform any walking 
 exercise at all per week , group b performed walking for less than 200 
 minutes per week , group c performed walking for 200 minutes or more per 
 week , max .
bp : maximum diastolic blood pressure , ve / vo2 : ve for o2 , 
 ve / vco2 : ve for co2 , vd : physiological dead space , vd / vt : 
 physiological dead space / tidal volume ratio , br : breathing reverse ( maximum exercise 
 ventilation / maximal voluntary ventilation ) , vo2max : maximal oxygen uptake , 
 at : anaerobic threshold ( % , o2 uptake at at / peak o2 uptake ) , 
 o2 pulse : peak o2 pulse ( vo2/hr ) values are meansd , * p<0.05 , group a did not perform any walking 
 exercise at all per week , group b performed walking for less than 200 
 minutes per week , group c performed walking for 200 minutes or more per 
 week , rmr : resting metabolic rate , bmi : body mass index , ffm : fat free mass , vfa : 
 visceral fat area , whr : waist - hip ratio
the present study examined the effects of normal weekly exercise time on vo2max 
 and rmr in adults . vo2max and rmr were significantly different among the three 
 groups divided by weekly exercise at normal times .
gilliat - wimberly et al . studied healthy 
 female subjects aged 3550  years who were divided into groups performing physical activity 
 for at least nine hours per week or for approximately one hour per week20 .
the rmr of the group performing activity for at least 
 nine hours was significantly higher than that of the group performing physical activity for 
 approximately one hour . in a study by toth et al . , individuals aged 3659  years were divided 
 into three groups based on types of exercise : a resistance - trained group , an aerobic - trained 
 group , and an untrained group .
the aerobic - trained group 
 showed significantly higher rmr than the untrained group and higher rmr values than the 
 resistance - trained group , although the differences were not significant .
in addition , the 
 aerobic - trained group showed significantly higher vo2max than the untrained and 
 resistance - trained groups . in a study by mccargar et al .
, overweight women aged 2549  years 
 were divided into groups with above or below average fitness levels by using a 1-mile timed 
 walking test22 .
the vo2max of 
 the group with below average fitness levels was statistically significantly lower than the 
 group with above average levels .
therefore , exercise duration and type at normal times and 
 fitness levels have positive effects on vo2max and rmr .
shim et al . reported that when individuals aged 55  years or older underwent muscle strength 
 training once per week for eight weeks , rmr significantly increased from weeks 4516 .
reported that when male 
 subjects aged 3545 were divided into a fat group and a normal group and performed aerobic 
 exercise three times per week for eight weeks , both groups showed statistically significant 
 increases in vo2max17 . 

reported that when university student athletes were divided 
 into an aerobic swimming group and an anaerobic swimming group and swam intermittently at 
 least three times per week for six weeks , both groups showed statistically significant 
 increases in vo2max18 . in a 
 study by osei - tutu et al .
, individuals were divided into two groups and walked five times 
 per week for eight weeks ; both the group that walked for 30 minutes continuously per day and 
 the group that walked for 10 minutes three times per day showed statistically significant 
 increases in vo2max19 .
the 
 subjects in the present study showed differences in vo2max and rmr for different 
 amounts of exercise at normal times .
the above studies show that diverse exercises that are 
 performed consistently will positively affect vo2max and rmr . in the present study , not only vo2max and rmr but
at is a direct indicator of aerobic capacity28 and is widely used in setting the 
 intensity of aerobic training of healthy subjects29 and individuals with chronic diseases ( e.g. , coronary heart 
 disease30 , hypertension31 , or obesity32 ) .
a study 
 by farrel et al.33 reported that 
 long - distance running was associated with both vo2max and at .
group c in the present study is thought 
 to have shown higher at values compared with the other groups because group c performed 
 larger amounts of exercise at normal times . in the present study , weekly exercise at normal times affected vo2max , rmr , and 
 at
, all of which are indicators of individual physical abilities and health , and these three 
 values increased with the amount of exercise .
in addition , vo2max , rmr , and at 
 are considered to be closely related , consistent with the results of previous studies .
the 
 results of the present study should be helpful for the development of exercise programs to 
 enhance individual physical abilities .
 [ purpose ] the present study examined the effect of individual weekly exercise time on 
 resting metabolic rate and vo2max ( maximal oxygen uptake ) , which are important 
 components of individual health indexes . 
 [ subjects and methods ] thirty healthy adults 
 participated in this study . 
 questionnaires were used to divide the participants into 
 groups based on average weekly walking . resting metabolic rate 
 was measured using a 
 respiratory gas analyzer . 
 graded exercise tests were conducted using a treadmill , and the 
 modified bruce protocol was used as an exercise test method . [ results ] vo2max , 
 anaerobic threshold , and resting metabolic rate were significantly different among the 
 groups . 
 [ conclusion ] average weekly exercise time affected vo2max , resting 
 metabolic rate , and anaerobic threshold , all of which are indicators of individual 
 physical ability and health . 
 these values increased as the individual amount of exercise 
 increased . 
 in addition , vo2max , resting metabolic rate , and anaerobic threshold 
 were found to be closely correlated . 
 these findings were consistent with the results of 
 similar previous studies . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION