| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Atherosclerosis and Lipoproteins |
From the Departments of Cardiovascular Medicine and Laboratory Medicine, Hokkaido University Graduate School of Medicine, and Sapporo Health Promotion Center, Sapporo, Japan.
Correspondence to Koichi Okita MD, PhD, Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan. E-mail okita{at}med.hokudai.ac.jp
| Abstract |
|---|
|
|
|---|
Methods and Results A total of 227 apparently healthy women were recruited, and 199 subjects (average age 52 years) completed a 2-month weight reduction program consisting of supervised aerobic exercises. After the program, weight was reduced from 65.8 to 62.8 kg (P<0.0001), and all conventional variables were remarkably improved. Similarly, CRP levels were significantly decreased, from 0.63 (0.28 to 1.19) to 0.41 (0.18 to 0.80) mg/L (P<0.0001). However, in contrast to other variables, the changes in CRP levels were not proportionally associated with the extent of weight reduction. In the quartile analysis of % weight reduction, the largest weight reduction quartile did not show significant decreases in CRP levels, whereas moderate quartile showed remarkable CRP decreases.
Conclusions Exercise training with weight reduction disproportionately lowered CRP levels. Considering inflammatory status, there might be an optimal pace of exercise with weight loss.
C-reactive protein (CRP) is a promising predictor for cardiovascular disease and may be a mediator for atherogenesis. Although it has been reported that diet-induced weight loss lowered CRP levels, the effect of exercise training on CRP is still unclear. We examined effects of exercise training with weight loss on CRP levels, finding that exercise training with weight reduction disproportionately lowered CRP levels. Considering inflammatory status, there might be an optimal pace of exercise with weight loss.
Key Words: C-reactive protein atherosclerosis inflammation obesity risk factors exercise
| Introduction |
|---|
|
|
|---|
See pages 1743 and 1874
Several studies have shown that elevated CRP levels are closely related to obesity.1013 It has been proposed that adipose tissue-secreted interleukin (IL)-6 may contribute to the elevated CRP levels observed in obesity.14,15 Two previous studies demonstrated that CRP levels were reduced in correspondence with diet-induced weight loss in a small sample of obese women.16,17
Exercise training is another therapy that can reduce weight and has protective effects against atherosclerosis, and it is more ideal in a clinical situation without muscle wasting compared with calorie restriction alone. However, the effect of regular exercise training on CRP levels is still unclear. Past cross-sectional studies have reported the significant relation between physical activity and CRP levels.18,19 In contrast, a recent study reported no significant relation between them.20
The purpose of this study was to determine the effects of exercise training with weight reduction on obesity-related inflammatory markers and conventional cardiovascular risk factors.
| Methods |
|---|
|
|
|---|
Weight Reduction Protocol
We used a 2-month weight reduction program, which consisted of supervised aerobic exercises. Subjects were assigned to a supervisor and given an exercise program 2 days a week. All subjects participated in an aerobic dance workout for 80 minutes, then did additional bicycle or treadmill exercises for 30 to 60 minutes at which they were instructed to maintain a continuous 60% to 80% of the peak heart rate according to an initial exercise test. In addition to supervised exercise training, subjects were recommended to perform home-based exercise
1 days a week. Only at the baseline examination did dieticians make simple nutritional education suitable for exercise training to the subjects.
Clinical and Anthropometric Measurements
At baseline and after the weight reduction program, subjects came to our institution to provide data on blood, physical measurements, muscle strength, and exercise tolerance. Exercise tolerance was estimated by electromechanical bicycle ergometer with an incremental protocol (25 W/2 minutes) and expressed as calculated peak oxygen uptake. Thigh strength was measured by an Anaeropress 3500 (Combi). Measurements of waist (narrowest circumference viewed from the front) and hip (largest horizontal circumference around the buttocks) were recorded. Abdominal wall fat (maximal thickness of preperitoneal fat at the anterior surface of the liver) and thigh muscle thickness at the anterior middle portion between the knee and the anterior crest of the ilium were evaluated with ultrasound tomography. Resting heart rate and blood pressure were measured. ECG and chest x-ray film were also examined.
Laboratory Measurements
Fasting venous blood samples were collected at the same time in the morning, after subjects had abstained from all food and drink, except water, for at least 12 hours, and from vigorous activity also for at least 12 hours. Fasting total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides, glycohemoglobin A1c (HbA1c), insulin, and glucose levels were measured. In addition, white blood cell count (WBC), uric acid, and liver function profiles such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and
-glutamyl transpeptidase (
-GTP) were also measured. Insulin sensitivity was calculated by using the homeostasis assessment model (HOMA-R), a mathematical estimate of insulin sensitivity based on fasting glucose and insulin concentrations.21 Serum high-sensitivity CRP and amyloid A protein (SAA) levels were measured by a latex-enhanced immunonephelometric assay.
Statistical Analysis
Statistical analysis was performed using Statview 5.0 (SAS Institute). The 2-sided t test for paired samples was used to determine the significance of differences between several measurements before and after the weight reduction program. The significance of any differences in medians for paired data were evaluated with a nonparametric Wilcoxon signed rank sum test. Spearman rank correlation coefficients were used to quantify the correlations. In the quartile analysis, effects of exercise training on variables within each quartile group were evaluated in the manner described above for paired data. Data are presented as mean (SD) or as median (interquartile range) for skewed variables. Significance levels are shown for all comparisons and relationships where P<0.05.
| Results |
|---|
|
|
|---|
|
|
Physical and metabolic characteristics at baseline and after a 2-month weight reduction program are shown in Table 3. Effects of exercise training were similarly obtained in premenopausal and postmenopausal women. Body weight was substantially reduced by 3.0 (1.9) kg, representing 4.6 (2.9)% of initial weight in total subjects. Other obesity measures were also significantly reduced. On the other hand, thigh muscle thickness was unchanged. These findings indicated that only body fat, but not muscle mass, was reduced by this weight reduction program. Fitness status variables were improved, and all of the laboratory variables except HDL cholesterol were improved after the program. The absence of any improvement in HDL cholesterol after the program could be because of altered lipase activity during active phase of weight loss.22 Although HDL cholesterol was reduced, total/HDL cholesterol ratio was significantly improved. Similarly, significant reduction in CRP, SAA, and WBC levels was also observed after the program. Although CRP (P<0.05) and SAA (P<0.01) levels at baseline were significantly higher in postmenopausal women than in premenopausal women, effects of exercise training on obesity measures, fitness status, traditional risks, and inflammatory markers were similar between premenopausal and postmenopausal women.
|
The correlations between the extent of weight reduction and waist reduction (% to initial value) and variables are shown in Table 4. Waist reduction was not related to most of the changes in studied variables except waist-hip ratio and WBC. Although waist girth potentially relates to visceral fat, its change may be affected not only by reduction in visceral fat but also by abdominal muscle fitness and an accidental error in measurement. On the other hand, weight reduction was significantly associated with improvements in obesity measures, fitness status, blood pressure, lipid profiles, FBS, insulin, and HOMA-R. However, changes in CRP, SAA, and uric acid were not significantly correlated with the extent of weight reduction. Additionally, no significant correlation between changes in CRP and body weight was seen in premenopausal women (n=91, r=0.19, P=0.06) or especially in postmenopausal women (n=108, r=0.07, P=0.47).
|
To further examine the relationship between the extent of weight reduction and the changes in variables, data were observed according to weight reduction quartiles (Figure). Subjects were divided on the basis of % weight reduction to initial weight. Mean weight reduction in the various groups was as follows: group A, 0.8 (0.8) kg, 1.1 (1.2) %; B, 2.3 (0.4) kg, 3.5 (0.5) %; C, 3.5 (0.6) kg, 5.4 (0.7) %; and D, 5.4 (1.1) kg, 8.4 (1.6) %. No significant differences in baseline characteristics were observed among quartile groups. Greater weight reduction corresponded to greater reduction in diastolic pressure, triglycerides, and fasting insulin. Other traditional risks showed a similar trend inconsistent with the results in Table 4; however, the pattern of CRP differed from that of those variables. The largest weight reduction group (D) did not show a proportional decrease in CRP levels corresponding to weight reduction. The SAA levels showed a similar trend. Interestingly, the serum uric acid levels were rather increased in group D, although this increase did not reach statistical significance (P=0.14).
|
The correlations between changes in CRP levels and other variables are shown in Table 5. Only changes in serum uric acid, AST, ALT,
-GTP, and SAA were significantly correlated with CRP changes by Spearman rank correlation. A multiple regression analysis was performed to evaluate the relation of the changes in all studied variables to CRP levels. Changes in SAA and WBC were independently related to changes in CRP (R2=0.23, P<0.0001, P=0.02, for SAA, WBC, respectively).
|
| Discussion |
|---|
|
|
|---|
Previously, a few studies examined the effects of diet-induced weight reduction on CRP levels. Bastard et al14 reported that IL-6, but not CRP, was reduced by weight loss after a very lowcalorie diet had been imposed for 3 weeks in 8 lean and 21 obese women, although a trend toward reduced CRP was noted. On the other hand, Heilbronn et al16 found that CRP was significantly decreased by 26% in 83 obese women after weight loss on very lowfat diets for 3 months. Tchernof et al17 also reported that weight loss with low-calorie diets for long periods (average, 13.9 months) reduced CRP levels in 26 obese postmenopausal women. In the present study, we used a weight reduction program using exercise training with a simple nutritional education, a program that could also reduce CRP levels. This program is an appropriate and reasonable method for weight reduction in a clinical situation and sustains muscle mass and physical ability. Concerning exercise training, Smith et al30 reported that a long-term (6 months) exercise tended to reduce CRP levels in 34 persons at risk of developing ischemic heart disease, but this reduction did not reach statistical significance (P=0.12). Although there were differences in the subjects characteristics, the training program, and the length of the training period, it seemed that the small number of subjects in their study might be a major reason for different statistical results between their study and ours. Besides, there might possibly have been some adverse effects of exercise on CRP in their study setting.
There could be several mechanisms whereby exercise training or weight reduction decrease CRP levels. It has been proposed that adipose tissuesecreted IL-6 and tumor necrosis factor-
may contribute to the elevated CRP levels observed in obesity.14,15 Thus, exercise training may reduce CRP levels adequately by reducing adiposity. In addition, increased antioxidant capacity31 and improved endothelial function32 by exercise training are potential mechanisms for decreased CRP levels. Improvements in other atherogenic risks as well as weight reduction by exercise training may also be responsible for decreased CRP levels.
In the cross-sectional analysis, in addition to measures of obesity, fasting glucose, insulin, HOMA-R, HbA1c, lipid profiles, and fitness status (exercise tolerance and muscle strength) were significantly related to CRP levels. Those variables were significantly improved after the program. Although no significant correlation was observed between changes in CRP and those variables, improvements in those factors likely affected the CRP levels. On the other hand, changes in serum uric acid and other inflammatory variables were significantly correlated with CRP changes. WBC and SAA might be partly coregulated with CRP through inflammatory mediators. Serum uric acid has also been suggested to be an inflammatory mediator in atherosclerotic plaque.33
Other important findings of our study were that liver function profiles AST, ALT, and
-GTP were cross-sectionally and dynamically related to CRP levels. In healthy subjects, the levels of AST, ALT, and
-GTP might be related to liver fatness. Fatty liver associated with obesity may be the major cause of the relationship between them. Acute phase proteins are produced by the liver through stimulation by inflammatory cytokines, which could be excreted from adipose tissue.14,15 It appears that adipose tissue in the liver could stimulate the liver very effectively to produce CRP and SAA.
We observed the subjects for 2 months in the present study. Further study is needed to examine long-term outcomes, and CRP must be measured during maintenance period of target weight.
We conventionally measured the waist girth at the narrowest circumference. It may be difficult to evaluate a precise change in visceral obesity after weight loss with this technique. The precise measurement of a change in visceral obesity could help stimulate further investigation into the factors affecting the changes in CRP levels.
| Conclusion |
|---|
|
|
|---|
Received November 11, 2003; accepted July 2, 2004.
| References |
|---|
|
|
|---|
, in vivo. J Clin Endocrinol Metab. 1997; 82: 41964200.
production after a 5-km run. Eur J Clin Invest. 1998; 28: 866872.[CrossRef][Medline]
[Order article via Infotrieve]
This article has been cited by other articles:
![]() |
R. P. Sloan, P. A. Shapiro, R. E. DeMeersman, P. S. McKinley, K. J. Tracey, I. Slavov, Y. Fang, and P. D. Flood Aerobic exercise attenuates inducible TNF production in humans J Appl Physiol, September 1, 2007; 103(3): 1007 - 1011. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. J. Kullo, M. Khaleghi, and D. D. Hensrud Markers of inflammation are inversely associated with VO2 max in asymptomatic men J Appl Physiol, April 1, 2007; 102(4): 1374 - 1379. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Selvin, N. P. Paynter, and T. P. Erlinger The Effect of Weight Loss on C-Reactive Protein: A Systematic Review Arch Intern Med, January 8, 2007; 167(1): 31 - 39. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Sinner, A. R. Folsom, L. Harnack, L. E. Eberly, and K. H. Schmitz The Association of Physical Activity with Lung Cancer Incidence in a Cohort of Older Women: The Iowa Women's Health Study Cancer Epidemiol. Biomarkers Prev., December 1, 2006; 15(12): 2359 - 2363. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Kapiotis, G. Holzer, G. Schaller, M. Haumer, H. Widhalm, D. Weghuber, B. Jilma, G. Roggla, M. Wolzt, K. Widhalm, et al. A Proinflammatory State Is Detectable in Obese Children and Is Accompanied by Functional and Morphological Vascular Changes Arterioscler. Thromb. Vasc. Biol., November 1, 2006; 26(11): 2541 - 2546. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. K. Koh, S. H. Han, and M. J. Quon Inflammatory Markers and the Metabolic Syndrome: Insights From Therapeutic Interventions J. Am. Coll. Cardiol., December 6, 2005; 46(11): 1978 - 1985. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. K. Ray, C. P. Cannon, R. Cairns, D. A. Morrow, N. Rifai, A. J. Kirtane, C. H. McCabe, A. M. Skene, C. M. Gibson, P. M. Ridker, et al. Relationship Between Uncontrolled Risk Factors and C-Reactive Protein Levels in Patients Receiving Standard or Intensive Statin Therapy for Acute Coronary Syndromes in the PROVE IT-TIMI 22 Trial J. Am. Coll. Cardiol., October 18, 2005; 46(8): 1417 - 1424. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Fosslien Cardiovascular Complications of Non-Steroidal Anti-Inflammatory Drugs Ann. Clin. Lab. Sci., October 1, 2005; 35(4): 347 - 385. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. A. Lakka, H.-M. Lakka, T. Rankinen, A. S. Leon, D.C. Rao, J. S. Skinner, J. H. Wilmore, and C. Bouchard Effect of exercise training on plasma levels of C-reactive protein in healthy adults: the HERITAGE Family Study Eur. Heart J., October 1, 2005; 26(19): 2018 - 2025. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. W. Zieske, R. P. Tracy, C. A. McMahan, E. E. Herderick, S. Homma, G. T. Malcom, H. C. McGill Jr, J. P. Strong, and for the Pathobiological Determinants of Atheroscle Elevated Serum C-Reactive Protein Levels and Advanced Atherosclerosis in Youth Arterioscler. Thromb. Vasc. Biol., June 1, 2005; 25(6): 1237 - 1243. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Esposito, R. Marfella, D. Giugliano, T. O. Obisesan, J. M. Hagberg, K. Okita, H. Nishijima, and T. Murakami Fitness Versus Fatness: the Debate Continues Arterioscler. Thromb. Vasc. Biol., March 1, 2005; 25(3): e20 - e21. [Full Text] [PDF] |
||||
![]() |
J.-P. Despres CRP and Risk of Coronary Heart Disease: Can Exercise Training Cool Down the Flames? Arterioscler. Thromb. Vasc. Biol., October 1, 2004; 24(10): 1743 - 1745. [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
ATVB Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2004 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |