537
The Effects of Acute Moderate Exercise on Serum Lipids and Lipoproteins in Mildly Obese Women R. Lee, D. Nieman, R. Raval, J. Blankenship, J. Lee School of Public Health, Loma Linda University
eride (TG) and higher high-density lipoprotein cholesterol R. Lee, D. Nieman, R. Raval, J. Blankenship
and J. Lee, The Effects of Acute Moderate Exercise on Serum Lipids and Lipoproteins in Mildly Obese Women. IntJ Sports Med, Vol 12, No 6, pp 537—542, 1991.
Accepted after revision: February 25, 1991
The extent and duration of serum lipid and lipoprotein changes were examined in 12 mildly obese women who walked 45 minutes at 60 % VO2max in a labora-
tory setting. A two-factor, 2 x 6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest) and the second factor was time (six times of measurement over a 24-hour period) with treatment counterbalanced. The patterns of change in total high-
density lipoprotein-cholesterol (HDL-C) [F(5,55) 5.75, p 1 hour at > 70% of
VO2max) (1,7,9, 10, 16, 17, 19, 20, 31, 34, 35, 38). In the few
studies employing acute exercise of moderate intensity and duration ( ihour at 70% VO2max) (2—4, 14, 17, 21, 36), only Berger (2) utilized a resting condition for comparison, and none used walking as a modality of exercise. Although most researchers have found that acute moderate exercise is associated with an increase in HDL-C, variable responses have been reported for TC and TG.
Walking has a high compliance rate, is a popular activity, and many consider it the best overall exercise for most persons (18, 28). Walking is easily incorporated into a
busy time schedule, companionable, unlikely to cause injuries, and requires no special equipment, skills, or facility. Studies suggest that most adults can attain a cardiovascular training effect from brisk walking (29). We decided to investigate the extent and duration of the effect of an acute moderate walk on serum lipid and lipoprotein concentrations in women, allowing the subjects to serve as their own controls with treat-
ment order counterbalanced. It was hoped that this would shed light on an important question: will a single bout of moderate physical activity such as brisk walking result in significant lipid and lipoprotein changes?
Material and Methods Introduction
Cross-sectional and, to a more limited extent, prospective studies show that men and women participating in vigorous endurance-type exercise have lower plasma triglyctnt.J.SportsMed. 12(1991)537—542 GeorgThieme Verlag StuttgartNewYork
Subjects Twelve women were recruited from a previous study of 36 women conducted in our laboratories the previous year (15). Women were selected who met the following criteria: 24—45 years of age, premenopausal, no tobacco use, no history of alcohol or drug abuse, no current use of medications (except oral contraceptives), absence of hypertension and diabetes, and no family history of heart disease. All subjects were requested to exercise aerobically for at least 30 minutes, three
Downloaded by: East Carolina University. Copyrighted material.
Abstract
days per week, for six weeks prior to the study, and to daily record this in personal logs. In addition, each subject practiced walking on a treadmill for 45 minutes at least 72 hours before
their testing appointment. Subjects voluntarily signed an informed consent statement approved by the Loma Linda University Institutional Review Board for Human Studies.
Baseline Body Composition and Treadmill Testing One week prior to the scheduled research, subjects came to the Human Performance Laboratory (HPL) for orientation, and measurement of body composition and aerobic capacity. From a maximal-graded exercise test, treadmill speeds corresponding to 60% VO2max were calculated for use during the walking test.
Body density was determined by hydrostatic weighing, as outlined by Pollock et al. (28), with the formula of
Sin (33) used to determine the percent body fat. Residual volume was measured with the Jaeger constant volume, variable pressure plethysmograph (Erich Jaeger GmbH and Co., Würzburg, Germany).
Maximal graded exercise was conducted utilizing a protocol developed in our laboratories. The treadmill test started with a workload of 4.05 kph (2.5 mph) and 0% grade, with the speed increased by 0.8 kph (0.5 mph) every 3 minutes until 7.3 kph (4.5 mph) was reached. The grade was then increased 3 % every 3 minutes until exhaustion. Heart rate, ventilation, oxygen uptake, and respiratory exchange
ratio (R) were recorded during the last 15 seconds of each three-minute stage and at the subject's point of exhaustion. Maximal exercise performance was defined as an R above 1.15, a maximal heart rate within one standard deviation (± 12 bpm) of predicted values, and the subject's inability to continue despite urging by testing staff. Testing was conducted using the Quinton Q4000 stress test system and Q55 treadmill (Quinton Instrument Co., Seattle, WA). Metabolic measurements were taken with the Sensor Medics MMC Hori-
zon system 4400 metabolic cart (Sensor Medics, Anaheim, CA).
Experimental Design A two-factor, 2 x 6 design with repeated measures on both factors was used. The first factor was condition (exercise and rest) and the second factor was time of measurement (six times of measurement over a 24-hour period). Treatment order was counterbalanced, with subjects serving as their own controls.
Following baseline testing, each subject reported to the HPL at 0630 on two separate Sundays one week apart having avoided all food and beverages for 12 hours and exercise for 36 hours. Half the group was randomly selected to engage in exercise, the other half to rest the first Sunday, with conditions reversed the following week. Heart rate and metabolic measurements were taken at 0700, 0715, 0730, 0745, and 0800 with the same instruments used in baseline testing.
Care was taken to ensure that measurement procedures and lab environment were exactly the same for
R. Lee, D. Nieman, R. Raval, J. Blankenship, J. Lee
both conditions. Blood samples were taken at 0700, 0800, 0930, 1100, 1300, and the following morning at 0700. During the experimental session, subjects walked at 60% VO2max for 45 minutes from 0715 to 0800 while subjects in the rest condition sat quietly 5 meters away. Following the exercise and rest session (0715 to 0800), all subjects were taken to the lounge area of the HPL where they rested quietly in-between blood samples from 0800 to 1300. At 0930, a meal of cereal (GrapeNuts), 2% fat milk, and raisins were fed to each subject in premeasured quantities corresponding to 8 kilocalories per kilogram of body weight and providing 16% of calories as protein, 70% as carbohydrate, and 14% as fat. Subjects remained in the
HPL until 1300, and then were allowed to return to their homes. Subjects returned to the HPL the next morning at 0700 after having fasted for 12 hours for their final blood samples.
Blood Analysis Blood samples were drawn from an antecubital vein using a disposable syringe with subjects in the seated position. Samples for lactate analysis were immediately transferred to Vacutainers (Becton Dickinson Vacutainer Systems,
Rutherford, NJ) containing an oxalate/fluoride anticoagulant, mixed, chilled for 10 minutes in ice, and centrifuged for 10 minutes to separate cells from plasma. The plasma was then carefully pipetted into cryogenic vials, immediately stored at 2—6 °C, and analyzed later the same day using a Sigma lactate kit (procedure 826-UV, Sigma Diagnostics, St. Louis, Mo). All
spectrophotometric measurements were done using a Beckman DU2 spectrophotometer (Beckman Instruments, Inc., Fullerton, CA). Blood for complete blood counts were transferred to Vacutainers containing EDTA, stored at 2—6 °C, and analyzed within 24 hours using Coulter S-Plus IV instrumenta-
tion (Coulter Electronics, Inc., Hialeah, Florida). Plasma volume changes were determined using the method of Dill and Costill (6). The remaining blood was transferred to Vacutainers containing no anticoagulant, allowed to clot at room temperature for 30 minutes, and centrifuged for 15 minutes. The serum was then transferred to cryogenic vials, stored at 2—6 °C until all samples were collected, and then frozen at —70 °C for later analysis. Samples were thawed under refrigeration, vortexed for 5 to 10 seconds, and analyzed within 48 hours using commercial kits for TG (procedure 336, Sigma Diagnostics,
St. Louis), glucose (procedure 315, Sigma Diagnostics, St. Louis, MO), and TC (procedure 352, Sigma Diagnostics, St. Louis, MO). Inter-assay variation was avoided by analyzing all samples from individual subjects in a single run. Instructions outlined in each procedure were followed. Controls were run after every tenth sample using a commercially available
control sera (product no. A 2034, Sigma Diagnostics, St. Louis, MO). Assays of control sera for TG, glucose, and IC yielded coefficients of variation of 3.1%, 4.5%, 3.7% respectively. Values for LDL-C were calculated as follows: LDLC=TC-[HDL-C+(O.16 x TG)] (5).
In addition, total HDL-C and HDL3-C were analyzed with a double precipitation method using a com-
bined solution of dextran-sulfate (Mr 50,000 5,000, Sochibo, SA, Boulogne, France) and magnesium chloride (Sigma Diagnostics, St. Louis, MO) as outlined by Talameh et
al. (37). Briefly, HDL-C was fractionated by mixing serum samples with a solution comprising equal parts of 2% dextran sulfate and 0.6 mol/l MgCI2, holding at room temperature for
Downloaded by: East Carolina University. Copyrighted material.
538 mt. J. Sports Med. 12(199])
2.2
73.8 34.2
2.4
26.3 76.6 184
0.62 2.4
2 1.7
4
I0
36.9 163
mmoI/I
Age (years) Height (cm) Weight (kg) Percent body fat VO2max (mi/kg/minI VEmax (liter/mm) HRmax (beats/mm)
c'I,
12
n
r
Subject characteristics
= 0
p TIIIL
Table 1 Subject characteristics (mean SE)
II
mt. J. Sports Med. 12(1991) 539
Effects ofAcute Moderate Exercise in Mildly Obese Women
Table 2 Daily intake of select nutrients for three days prior to and including day of testing by condition (mean SE) Condition
19.9 11.7 16.7 171
19.2 6.7 13.0 186 10,227
118 6.3 16 8.3 2.8
1842
3.2
0.6 0.9 45.6
10.9 17.7 164 16.9 5.8 11.8 124
1518
9230
2.5
24 1.9
64.7 251
69.7 22.7
112 4.0 13 7.5 2.8 2.0 2.9
29
Fig. 1 Effect of a 45-minute walk at 60% V. O2max (from 0715 to 0800) on serum total HDL-C, HDL2-C, and HDL3-C. HDL2-C+HDL -
C'=total HDL-C. =p
The Effects of Acute Moderate Exercise on Serum Lipids and Lipoproteins in Mildly Obese Women R. Lee, D. Nieman, R. Raval, J. Blankenship, J. Lee School of Public Health, Loma Linda University
eride (TG) and higher high-density lipoprotein cholesterol R. Lee, D. Nieman, R. Raval, J. Blankenship
and J. Lee, The Effects of Acute Moderate Exercise on Serum Lipids and Lipoproteins in Mildly Obese Women. IntJ Sports Med, Vol 12, No 6, pp 537—542, 1991.
Accepted after revision: February 25, 1991
The extent and duration of serum lipid and lipoprotein changes were examined in 12 mildly obese women who walked 45 minutes at 60 % VO2max in a labora-
tory setting. A two-factor, 2 x 6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest) and the second factor was time (six times of measurement over a 24-hour period) with treatment counterbalanced. The patterns of change in total high-
density lipoprotein-cholesterol (HDL-C) [F(5,55) 5.75, p 1 hour at > 70% of
VO2max) (1,7,9, 10, 16, 17, 19, 20, 31, 34, 35, 38). In the few
studies employing acute exercise of moderate intensity and duration ( ihour at 70% VO2max) (2—4, 14, 17, 21, 36), only Berger (2) utilized a resting condition for comparison, and none used walking as a modality of exercise. Although most researchers have found that acute moderate exercise is associated with an increase in HDL-C, variable responses have been reported for TC and TG.
Walking has a high compliance rate, is a popular activity, and many consider it the best overall exercise for most persons (18, 28). Walking is easily incorporated into a
busy time schedule, companionable, unlikely to cause injuries, and requires no special equipment, skills, or facility. Studies suggest that most adults can attain a cardiovascular training effect from brisk walking (29). We decided to investigate the extent and duration of the effect of an acute moderate walk on serum lipid and lipoprotein concentrations in women, allowing the subjects to serve as their own controls with treat-
ment order counterbalanced. It was hoped that this would shed light on an important question: will a single bout of moderate physical activity such as brisk walking result in significant lipid and lipoprotein changes?
Material and Methods Introduction
Cross-sectional and, to a more limited extent, prospective studies show that men and women participating in vigorous endurance-type exercise have lower plasma triglyctnt.J.SportsMed. 12(1991)537—542 GeorgThieme Verlag StuttgartNewYork
Subjects Twelve women were recruited from a previous study of 36 women conducted in our laboratories the previous year (15). Women were selected who met the following criteria: 24—45 years of age, premenopausal, no tobacco use, no history of alcohol or drug abuse, no current use of medications (except oral contraceptives), absence of hypertension and diabetes, and no family history of heart disease. All subjects were requested to exercise aerobically for at least 30 minutes, three
Downloaded by: East Carolina University. Copyrighted material.
Abstract
days per week, for six weeks prior to the study, and to daily record this in personal logs. In addition, each subject practiced walking on a treadmill for 45 minutes at least 72 hours before
their testing appointment. Subjects voluntarily signed an informed consent statement approved by the Loma Linda University Institutional Review Board for Human Studies.
Baseline Body Composition and Treadmill Testing One week prior to the scheduled research, subjects came to the Human Performance Laboratory (HPL) for orientation, and measurement of body composition and aerobic capacity. From a maximal-graded exercise test, treadmill speeds corresponding to 60% VO2max were calculated for use during the walking test.
Body density was determined by hydrostatic weighing, as outlined by Pollock et al. (28), with the formula of
Sin (33) used to determine the percent body fat. Residual volume was measured with the Jaeger constant volume, variable pressure plethysmograph (Erich Jaeger GmbH and Co., Würzburg, Germany).
Maximal graded exercise was conducted utilizing a protocol developed in our laboratories. The treadmill test started with a workload of 4.05 kph (2.5 mph) and 0% grade, with the speed increased by 0.8 kph (0.5 mph) every 3 minutes until 7.3 kph (4.5 mph) was reached. The grade was then increased 3 % every 3 minutes until exhaustion. Heart rate, ventilation, oxygen uptake, and respiratory exchange
ratio (R) were recorded during the last 15 seconds of each three-minute stage and at the subject's point of exhaustion. Maximal exercise performance was defined as an R above 1.15, a maximal heart rate within one standard deviation (± 12 bpm) of predicted values, and the subject's inability to continue despite urging by testing staff. Testing was conducted using the Quinton Q4000 stress test system and Q55 treadmill (Quinton Instrument Co., Seattle, WA). Metabolic measurements were taken with the Sensor Medics MMC Hori-
zon system 4400 metabolic cart (Sensor Medics, Anaheim, CA).
Experimental Design A two-factor, 2 x 6 design with repeated measures on both factors was used. The first factor was condition (exercise and rest) and the second factor was time of measurement (six times of measurement over a 24-hour period). Treatment order was counterbalanced, with subjects serving as their own controls.
Following baseline testing, each subject reported to the HPL at 0630 on two separate Sundays one week apart having avoided all food and beverages for 12 hours and exercise for 36 hours. Half the group was randomly selected to engage in exercise, the other half to rest the first Sunday, with conditions reversed the following week. Heart rate and metabolic measurements were taken at 0700, 0715, 0730, 0745, and 0800 with the same instruments used in baseline testing.
Care was taken to ensure that measurement procedures and lab environment were exactly the same for
R. Lee, D. Nieman, R. Raval, J. Blankenship, J. Lee
both conditions. Blood samples were taken at 0700, 0800, 0930, 1100, 1300, and the following morning at 0700. During the experimental session, subjects walked at 60% VO2max for 45 minutes from 0715 to 0800 while subjects in the rest condition sat quietly 5 meters away. Following the exercise and rest session (0715 to 0800), all subjects were taken to the lounge area of the HPL where they rested quietly in-between blood samples from 0800 to 1300. At 0930, a meal of cereal (GrapeNuts), 2% fat milk, and raisins were fed to each subject in premeasured quantities corresponding to 8 kilocalories per kilogram of body weight and providing 16% of calories as protein, 70% as carbohydrate, and 14% as fat. Subjects remained in the
HPL until 1300, and then were allowed to return to their homes. Subjects returned to the HPL the next morning at 0700 after having fasted for 12 hours for their final blood samples.
Blood Analysis Blood samples were drawn from an antecubital vein using a disposable syringe with subjects in the seated position. Samples for lactate analysis were immediately transferred to Vacutainers (Becton Dickinson Vacutainer Systems,
Rutherford, NJ) containing an oxalate/fluoride anticoagulant, mixed, chilled for 10 minutes in ice, and centrifuged for 10 minutes to separate cells from plasma. The plasma was then carefully pipetted into cryogenic vials, immediately stored at 2—6 °C, and analyzed later the same day using a Sigma lactate kit (procedure 826-UV, Sigma Diagnostics, St. Louis, Mo). All
spectrophotometric measurements were done using a Beckman DU2 spectrophotometer (Beckman Instruments, Inc., Fullerton, CA). Blood for complete blood counts were transferred to Vacutainers containing EDTA, stored at 2—6 °C, and analyzed within 24 hours using Coulter S-Plus IV instrumenta-
tion (Coulter Electronics, Inc., Hialeah, Florida). Plasma volume changes were determined using the method of Dill and Costill (6). The remaining blood was transferred to Vacutainers containing no anticoagulant, allowed to clot at room temperature for 30 minutes, and centrifuged for 15 minutes. The serum was then transferred to cryogenic vials, stored at 2—6 °C until all samples were collected, and then frozen at —70 °C for later analysis. Samples were thawed under refrigeration, vortexed for 5 to 10 seconds, and analyzed within 48 hours using commercial kits for TG (procedure 336, Sigma Diagnostics,
St. Louis), glucose (procedure 315, Sigma Diagnostics, St. Louis, MO), and TC (procedure 352, Sigma Diagnostics, St. Louis, MO). Inter-assay variation was avoided by analyzing all samples from individual subjects in a single run. Instructions outlined in each procedure were followed. Controls were run after every tenth sample using a commercially available
control sera (product no. A 2034, Sigma Diagnostics, St. Louis, MO). Assays of control sera for TG, glucose, and IC yielded coefficients of variation of 3.1%, 4.5%, 3.7% respectively. Values for LDL-C were calculated as follows: LDLC=TC-[HDL-C+(O.16 x TG)] (5).
In addition, total HDL-C and HDL3-C were analyzed with a double precipitation method using a com-
bined solution of dextran-sulfate (Mr 50,000 5,000, Sochibo, SA, Boulogne, France) and magnesium chloride (Sigma Diagnostics, St. Louis, MO) as outlined by Talameh et
al. (37). Briefly, HDL-C was fractionated by mixing serum samples with a solution comprising equal parts of 2% dextran sulfate and 0.6 mol/l MgCI2, holding at room temperature for
Downloaded by: East Carolina University. Copyrighted material.
538 mt. J. Sports Med. 12(199])
2.2
73.8 34.2
2.4
26.3 76.6 184
0.62 2.4
2 1.7
4
I0
36.9 163
mmoI/I
Age (years) Height (cm) Weight (kg) Percent body fat VO2max (mi/kg/minI VEmax (liter/mm) HRmax (beats/mm)
c'I,
12
n
r
Subject characteristics
= 0
p TIIIL
Table 1 Subject characteristics (mean SE)
II
mt. J. Sports Med. 12(1991) 539
Effects ofAcute Moderate Exercise in Mildly Obese Women
Table 2 Daily intake of select nutrients for three days prior to and including day of testing by condition (mean SE) Condition
19.9 11.7 16.7 171
19.2 6.7 13.0 186 10,227
118 6.3 16 8.3 2.8
1842
3.2
0.6 0.9 45.6
10.9 17.7 164 16.9 5.8 11.8 124
1518
9230
2.5
24 1.9
64.7 251
69.7 22.7
112 4.0 13 7.5 2.8 2.0 2.9
29
Fig. 1 Effect of a 45-minute walk at 60% V. O2max (from 0715 to 0800) on serum total HDL-C, HDL2-C, and HDL3-C. HDL2-C+HDL -
C'=total HDL-C. =p
