there exists sufficient evidence which links the diseased state of atherosclerosis to elevated levels of total cholesterol ( tc ) , low - density lipoproteins cholesterol ( ldl - c ) , very low - density lipoprotein cholesterol ( vldl - c ) , and triglycerides ( tg ) ( 14 , 18 , 24 ) .
current research suggests that atherosclerosis is linked to the frequent and chronic elevation of postprandial lipemia ( 14 , 29 ) .
an increase in postprandial triglycerides ( ppt ) is complicated by the increased daily ingestion of multiple fatty meals ; as is commonly seen in first - world populations ( 14 ) .
moderate - intensity walking at 60% and 50% vo2max for 90min has shown to be an effective tool in decreasing ppt ( 6 , 9 , 18 , 24 , 29 ) .
this decrease in ppt can be seen among both trained and untrained individuals , supporting the theory that the increase in tg clearance is independent of anthropomorphic changes ( 14 ) .
acute exercise creates a clearance of existing intramuscular cholesterol via the skeletal muscle which is replenished as skeletal muscle uptakes plasma vldl in the postprandial state ( 16 ) .
the decrease in circulating vldl allows for less competition of lpl activity and thereby allowing an increase in tg hydrolysis ( 14 , 16 ) .
additionally , there is an increase in skeletal muscle lpl activity with exercise , which aides in the attenuation of plasma tg concentrations ( 14 ) .
exercise effects on ppt are short lived and are insignificant 2448 hours post - exercise ( 14 , 16 ) .
current research has determined the optimal time to measure ppt following an oral fat tolerance tests ( oftt ) is 1216 hours post - exercise ( 14 , 24 , 28 ) .
exercise benefits measured directly prior to , or directly after , a high - fat meal show a decrease in effectively reducing ppt when compared to measured exercise benefits at 12 hours prior to the high - fat meal ( 30 ) .
research concerning lipid metabolism commonly utilizes a younger population ( 2050 years of age ) , creating a scarcity in data corresponding to older adults .
there is a presumed decrease in lpl activity with age , causing an increase in plasma tg ( 16 ) .
the mechanisms and parameters by which tg can be naturally reduced through exercise are of specific concern to an older population .
therefore , the purpose of this study was to discover whether 90 minutes of moderate - intensity exercise attenuates ppt among older adults .
subjects consisted of men ( 1 ) and women ( 7 ) of various activity levels with a minimum age of 50 years and a mean age of 588 .
subjects bmi was relatively homogeneous with a 26.54.2 average . a health history questionnaire as well as an informed consent advising them of procedures , risks , and benefits of the present study was completed .
subjects with the diseased conditions of known cardiovascular disease , hyperlipidemia , or diabetes were excluded from the present study .
subjects with signs or symptoms of cardiovascular , pulmonary , or metabolic disease , as defined by the american college of sports medicine ( acsm ) , were also not allowed to participate ( 1 ) .
subjects currently taking medication to monitor lipid metabolism , carbohydrate metabolism , or insulin therapy were also excluded ; as were smokers or those partaking in recreational drugs .
subjects with increased resting values prior to the exercise or control trial were also excluded ; those values were as follows : blood glucose was over 125mgdl , blood pressure greater than 160/100 mm hg , or total cholesterol over 240mgdl .
activity levels ranged from moderately active ( walking 3 days per week ) , to sedentary ( non - strenuous work activities ) .
this homogeneously active group has been selected to eliminate the synergistic effects of endurance training on ppt clearance ( 29 ) .
subjects participated in two , two - day , oftt trials and underwent the exercise trial first , followed by the control trial , with a minimum of seven days between trials . on day one of the two - day protocol ,
the oftt took place on day two of the two - day protocol among both control and exercise trial .
both trials underwent the same protocols for data collection ; however , exercise was omitted in the control trial and replaced with 90 minutes of rest ( seated none activity ) .
prior to data collection on day one and two subjects rested in a supine position for 15 minutes ; at the conclusion of which , resting hr , bp , lipid profile , and blood glucose were collected utilizing the alere cholestech ldx ( alere north america llc , orlando fl ) .
subjects were advised to abstain from alcohol for a 24-hour period prior to day one and continue to abstain until the conclusion of day two .
each subject kept a food journal , recording what they ate for the 24 hours prior to day one and concluding with the day two data collection .
this food journal was used to replicate the subject s diet prior to each oftt .
subjects were advised to abstain from exercise for 48 hours prior to day one and concluding with the day two data collection . on day one ,
between the hours of 18002000 , the exercise trial participated in a 90-minute walk of moderate intensity .
water intake was measured and replicated during the 90 minute rest period of the control trial .
subjects returned on day two between the hours of 07300800 after participating in a 1216 hour overnight fast .
after the resting vitals were obtained , subjects were given a 20 minute period in which to consume an oftt .
the oftt consisted of a standardized dennys milkshake containing 490 kcal , 92 g fat , 146 g cho , and 24 g protein .
a dose of 9000pcc lactase units was given in conjunction with the milkshake to ensure that the meal was easily digested .
hr , bp , lipid profile , and blood glucose was collected at 0 ( pre - oftt ) , 1 , 2 , 3 , and 4 hours postprandially .
two - way repeated measures anova - s were used to analyze the difference in tg , ldl , hdl , and glucose over time for the control and exercise trials .
a tukey post hoc was utilized to examine the differences within the data , when appropriate . an alpha level of p < 0.05 was considered statistically significant for all comparisons .
subjects consisted of men ( 1 ) and women ( 7 ) of various activity levels with a minimum age of 50 years and a mean age of 588 .
subjects bmi was relatively homogeneous with a 26.54.2 average . a health history questionnaire as well as an informed consent advising them of procedures , risks , and benefits of the present study was completed .
subjects with the diseased conditions of known cardiovascular disease , hyperlipidemia , or diabetes were excluded from the present study .
subjects with signs or symptoms of cardiovascular , pulmonary , or metabolic disease , as defined by the american college of sports medicine ( acsm ) , were also not allowed to participate ( 1 ) .
subjects currently taking medication to monitor lipid metabolism , carbohydrate metabolism , or insulin therapy were also excluded ; as were smokers or those partaking in recreational drugs .
subjects with increased resting values prior to the exercise or control trial were also excluded ; those values were as follows : blood glucose was over 125mgdl , blood pressure greater than 160/100 mm hg , or total cholesterol over 240mgdl .
activity levels ranged from moderately active ( walking 3 days per week ) , to sedentary ( non - strenuous work activities ) .
this homogeneously active group has been selected to eliminate the synergistic effects of endurance training on ppt clearance ( 29 ) .
subjects participated in two , two - day , oftt trials and underwent the exercise trial first , followed by the control trial , with a minimum of seven days between trials . on day one of the two - day protocol ,
the oftt took place on day two of the two - day protocol among both control and exercise trial .
both trials underwent the same protocols for data collection ; however , exercise was omitted in the control trial and replaced with 90 minutes of rest ( seated none activity ) . prior to data collection on day one and
two subjects rested in a supine position for 15 minutes ; at the conclusion of which , resting hr , bp , lipid profile , and blood glucose were collected utilizing the alere cholestech ldx ( alere north america llc , orlando fl ) .
subjects were advised to abstain from alcohol for a 24-hour period prior to day one and continue to abstain until the conclusion of day two .
each subject kept a food journal , recording what they ate for the 24 hours prior to day one and concluding with the day two data collection .
this food journal was used to replicate the subject s diet prior to each oftt .
subjects were advised to abstain from exercise for 48 hours prior to day one and concluding with the day two data collection . on day one , between the hours of 18002000 , the exercise trial participated in a 90-minute walk of moderate intensity .
the subjects wore polar heart rate monitors ( model ft7 , polar electro inc . ,
water intake was measured and replicated during the 90 minute rest period of the control trial .
subjects returned on day two between the hours of 07300800 after participating in a 1216 hour overnight fast .
after the resting vitals were obtained , subjects were given a 20 minute period in which to consume an oftt .
the oftt consisted of a standardized dennys milkshake containing 490 kcal , 92 g fat , 146 g cho , and 24 g protein .
a dose of 9000pcc lactase units was given in conjunction with the milkshake to ensure that the meal was easily digested .
hr , bp , lipid profile , and blood glucose was collected at 0 ( pre - oftt ) , 1 , 2 , 3 , and 4 hours postprandially .
two - way repeated measures anova - s were used to analyze the difference in tg , ldl , hdl , and glucose over time for the control and exercise trials .
a tukey post hoc was utilized to examine the differences within the data , when appropriate . an alpha level of p < 0.05 was considered statistically significant for all comparisons .
there exists no significant difference in triglycerides when comparing the exercise effect over time , and control effect over time .
there does exist a significant difference when examining the effect of time on ppt ( p < 0.05 ) .
this difference lies in the one , two , three , and four hours postprandial over the pre - prandial ( baseline ) measurement .
ppt increases along a predictable curve among both groups with a slight decrease among the exercise trial ( figure 1 ) .
there is a significant difference ( p < 0.05 ) of time at all points when compared against pre - feeding values ( figure 2 ) .
there exists a significant difference of time at the two and three hour points over the pre - feeding value ( figure 3 ) .
no significant difference among glucose values were found between the exercise and control groups over time . there was a significant difference ( p < 0.05 ) of time at the one , two , and three hour postprandial values over the pre - feeding time point ( figure 4 ) .
the main findings of this investigation is an acute bout of moderate - intensity exercise preformed 1216 hours prior to ingesting a high - fat meal does not attenuate ppt in older adults .
there was no difference in ppt when comparing the exercise group over time with the non - exercise group over time .
there exists a significant difference over time at all time points beyond the pre - feeding value .
this difference is to be expected among any population and originates from the natural process by which the body metabolizes food and experiences a rapid increase in tg .
previous examinations have discovered that a chronic exercise intervention is required to effect change in ldl and hdl , or exercise vigorous enough to elicit a deficit of 1100 kcal in one bout .
the decreased exercise influence in the present study is likely not sufficient to influence ldl and hdl values ( 14 , 23 ) .
conversely , a change in tg has been observed when eliciting a deficit of between 350700 kcal based on fitness ( lower fitness requiring lower kcal expenditure ) ( 14 ) .
tc experienced an increase upon feeding , and glucose followed the normal metabolic pattern of feeding , having an initial peak , followed by a decline to near pre - feeding values .
the findings of the present study are not consistent with similar investigations which have found a significant difference following a 90-minute moderate - intensity exercise bout and 1216 hour fast .
a decrease in ppt has been found when walking for 90 minutes at 50% vo2max , and 60% vo2max followed by a 1216 hour overnight fast in non - smoking males and females , trained and untrained , ages 2143 ( 3 , 6 , 10 , 29 ) .
exercise intensity as low as 30% vo2peak for 100 minutes has been shown to reduce ppt among eight young women , age 27  1 ( 18 ) .
the mean age in this present study was 58  8 ; therefore , age may be an indicator of a decrease in lpl activity with age , leading to an impaired ability to metabolize tg in older adults .
minimal research has been performed examining the effects of lpl activity on older adults ; however , reduced lpl activity in rodent models has shown defective fatty acid utilization and tg lipolysis leading to cardiac complications in older mice , including cardiac fibrosis ( 2 ) . increased lpl activity has been linked to reduced all - cause mortality ; likely attributed to a decrease in circulating cholesterol over time ( 27 ) . increased circulating vldl and
chylomicrons can penetrate the intima and perpetuate the diseased state of atherosclerosis ; therefore , it can be speculated that mutations in lpl production with age can decrease the exercise effect on tg .
an estimate of hr max was used in the present study , as it is more likely to appeal to an older population who may be unwilling ( or unable ) to perform a vo2max test .
the utilization of maximal heart rate by way of measuring exercise intensity has yielded successful investigations and is friendlier to sedentary populations ( as examined in the present investigation ) having not met the exercise guidelines as defined by acsm ( 1 , 19 ) .
the exercise intensity employed in the present study was 60% of estimated heart rate max which is similar to other investigations that have found a significant changes in ppt utilizing younger populations and exercise bouts of 90 minutes ( 6 , 9 , 10 , 29 ) .
the oftt used in the present study contained 92 g of fat and is similar to that of other investigations which have found a significant difference among exercise trials utilizing a fat content of 40 g , 80 g , 87 g , 98 g , and 140 g ( 4 , 6 , 11 , 26 ) .
researchers have had success catering the fat content to the lean mass or body mass of the participant ; this may be a more effective measure by which the fatty meal is delivered ( 5 , 7 , 10 , 17 , 19 , 20 , 29 ) . the present study used a standardized dennys in an effort to simulate a meal that is ingested daily by restaurant patrons .
the wide range of fat content and quality among researchers suggests the necessity for a standardized oftt ( 24 ) .
future researchers should consider incorporating a young population , as well as the older population , in an attempt to determine whether age is the divergent factor in tg metabolism .
additional limitations include the scheduled exercise trial prior to the control trial ; future studies should consider utilizing a randomized cross - over design , thus decreasing the risk of participants being conscience of their activity and eating habits leading up to the trial .
the subjects in the present study self - monitored their hr throughout the exercise trial and reported their heart rate verbally at 15 minute intervals ; future studies should consider constant researcher monitoring of hr . in conclusion ,
the results of the present study demonstrate that 90 minutes of moderate - intensity exercise 1216 hours prior to a fatty meal does not influence the rate of ppt clearance in subjects 50 years of age .
the present study has sought to determine whether the exercise response on tg among older adults is similar to that of younger populations ; whom have experienced an attenuation of tg under similar parameters ( 6 , 9 , 10 , 29 ) .
further research is needed on lpl activity among older adults and its influence on tg clearance .
 to determine whether 90 minutes of moderate - intensity exercise , prior to a high fat meal , attenuates postprandial triglycerides ( ppt ) in older adults . 
 eight sedentary older adult volunteers ( mean  sd age = 58  8 years , bmi 26.5  4.2 ) ; completed two trials consisting of exercise and a no - exercise control . 
 exercise trials involved 90 minutes of moderate - intensity exercise 60% heart rate reserve ( hrr ) . following exercise , an overnight fast of 1216 hours was performed . 
 participants were given a high fat meal that consisted of 146 grams of cho , and 92 grams of fat and instructed to rest . 
 lipid levels were collected at pre - feeding , 1 , 2 , 3 , and 4 hours post feeding . 
 the control trial involved no exercise , performed an overnight fast of 1216 hours , and was given the high fat meal followed by four hours of rest and data collection . 
 there was no difference in ppt between the control and exercise trials ( p < 0.05 ) . 
 triglycerides ( tg ) increased in both trials over pre - feeding values ( pre - feeding 123.13  65.03 con . 
 111  53.9 ex . 
 , 1hr 161.50  83.77 con . 
 149  71.03 ex . 
 , 2hrs 208.25  120.69 con . 
 177  97.29 ex . 
 , 3hrs 228  146.99 con . 
 147.25  87.64 ex . 
 , 4hrs 211.75  140.15 con . 
 169.5  68.14 ex ) . 
 no difference in triglycerides over time was observed among older adults between the exercise and control trials . 
INTRODUCTION
METHODS
Participants
Protocol
Statistical Analysis
RESULTS
DISCUSSION