International Journal of Clinical Medicine, 2013, 4, 532-538 Published Online December 2013 (http://www.scirp.org/journal/ijcm) http://dx.doi.org/10.4236/ijcm.2013.412092 Open Access IJCM Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men Michael R. Esco1, Robert L. Herron2, Stephen J. Carter2, Andrew A. Flatt1 1Human Performance Laboratory, Department of Physical Education and Exercise Science, Auburn University at Montgomery, Montgomery, USA; 2Exercise Physiology Laboratory, Department of Kinesiology, The University of Alabama, Tuscaloosa, USA. Email: mesco@aum.edu Received September 19th, 2013; revised October 17th, 2013; accepted November 12th, 2013 Copyright © 2013 Michael R. Esco et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Background: The primary purpose of this investigation was to determine the differences in resting heart rate variability and heart rate recovery between norm-referenced aerobic fitness groupings, independent of body composition, in Black men. Additionally, we sought to clarify the independent relationships that heart rate variability and heart rate recovery displayed with maximal aerobic fitness and selected body composition measures. Methods: Body mass index, waist circumference, and the sum of skinfold thickness were determined in forty Black men (23 ± 3 years). Each subject as- sumed a supine position while heart rate variability was analyzed for 5-minute and recorded as normalized high-fre- quency power and normalized low-frequency power to normalized high frequency ratio. A graded exercise treadmill protocol was performed to attain maximal aerobic fitness. Heart rate recovery was recorded at 1- and 2-minute of a cool-down period. Heart rate variability and heart rate recovery were compared across two groups whose maximal aerobic fitness was either below or above the normative mean value for the age group of men. Results: The results in- dicated that heart rate variability was higher in the group whose maximal aerobic fitness was above the normative mean value compared with the lower fit group (p < 0.05), but the differences disappeared when adjusting for body composi- tion (p > 0.05). Regression analysis revealed that the sum of skinfolds accounted for the variation in normalized high frequency power (R2 = 0.20, p < 0.05) and normalized low-frequency power to normalized high frequency ratio (R2 = 0.30, p < 0.05), while waist circumference accounted for the variation in heart rate recovery at 2-minute (R2 = 0.20, p < 0.05). Conclusion: The results suggest that heart rate variability and heart rate recovery hold independent relationships to body composition but not aerobic fitness in young-adult, Black men. Keywords: Skinfold Thickness; Waist Circumference; Cardiovascular; Autonomic 1. Introduction Heart rate variability (HRV) and heart rate recovery (HRR) are two non-invasive measures of cardiovascular- autonomic modulation [1-4]. HRV represents the auto- nomic controlled beat-to-beat oscillations that occur in heart rate, while HRR describes the parasympathetic- mediated decline in heart rate immediately following exercise [2,3]. The clinical importance of both markers stands in their ability to independently predict untoward cardiac events and early development of cardiovascular disease [2,4]. Recent evidence has suggested that HRV and HRR may reflect improved measures of physical fitness through lifestyle modification, yet the extent of this relationship remains unclear [5-7]. While several studies have indi- cated a possible link concerning aerobic fitness and body composition to HRV and HRR, much of the research emphasizes the relative importance of aerobic fitness. As a result, more research is needed to clarify the associa- tion of body composition with HRV and HRR [5,8-10]. Among the many factors contributing to disease states, the influence of race may be an important variable often overlooked. Accordingly, Blacks experience a greater pre- valence of cardiovascular mortality compared with Whites [11,12]. Blacks also tend to be less physically active and have lower levels of aerobic fitness [12-14]. Research has indicated the existence of biological differences re-
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men 533 garding body composition between races [15]. Despite the apparent health disparities between racial groups, some investigators have shown greater HRV at rest and faster HRR following exercise in Blacks compared with Whites. However, the findings remain equivocal as oth- ers have presented conflicting data [16-19]. As such, the inconsistency of these results has led to speculations that the relationship between physical fitness and cardiac- autonomic control may be race-dependent. Furthermore, Esco et al. [10] showed that cardiovas- cular autonomic modulation is significantly related to maximal aerobic fitness and body composition. However, of the independent variables analyzed in the study, the sum of skinfold thickness appeared to have the strongest independent relationship with HRV and HRR, compared with other body composition parameters and maximal aerobic fitness [10]. Unfortunately, the study analyzed mostly white men [10]. Therefore, race-specific study in this area involving only Black men is needed. The results of such investigation could have important implications related to lifestyle interventions designed to reduce the risk of cardiovascular disease in this at-risk and under- studied group. The primary purpose of this investigation was to de- termine if differences in HRV and HRR would be re- flected by norm-referenced aerobic fitness groupings, in- dependent of body composition in young-adult Black men. Additionally, we sought to clarify the independent relationships that HRV and HRR display with VO2max and selected body composition measures (e.g. body mass index [BMI], waist circumference [WC], and the sum of skinfold thickness [SF]) within the group. 2. Materials and Methods 2.1. Study Sample Forty young-adult Black men participated in the study (age = 23 ± 3 years, height = 180.0 ± 9.3 cm, weight = 82.8 ± 11.2 kg). Prior to study involvement, all subjects completed a health history questionnaire and were as- sessed to determine if they met inclusion criteria. All approved subjects were apparently healthy, free from cardiopulmonary, metabolic, and/or orthopedic impair- ments. At the time of data collection, all subjects were not taking any prescription or over-the-counter medica- tions, each displaying normal blood pressure (i.e. <140/ 90 mmHg). Subjects were non-smokers with normal electrocardiogram (ECG) readings, between the ages of 19 and 29 years, and self-reported race as Non-Hispanic/ Black over three generations. Written informed consent was obtained from each subject prior to study involve- ment. All research procedures were approved by the In- stitutional Review Board for Human Participants. 2.2. Procedures All data were collected during a single visit to the labo- ratory. For convenience, each subject selected a 2-hour time slot on any day to complete the experimental pro- cedures: from 7:00 AM and 9:00 AM, or from 9:00 AM and 11:00 AM. Subjects were instructed to avoid strenu- ous exercise for 24-h prior to the test, consumption of alcohol or sympathomimetic agents 12 hours before the test. Additionally, subjects were required not to eat at least 10-h prior to data collection. Height was measured with a wall-mounted stadiometer (SECA, Seca Instruments Ltd,Hamburg, Germany) and body weight was measured with a digital scale (TANITA BWB-800A, Tanita Corp, Tokyo, Japan) while the sub- jects stood erect without shoes. Body mass index (BMI) was determined as weight in kilograms divided by height in meters squared (kg·m−2). Waist circumference was measured with a Gulick spring loaded handle (Mabis, Tokyo, Japan) in accordance with current American Col- lege of Sports Medicine (ACSM) recommendations [20]. Calibrated skinfold calipers (Harpenden; Baty Interna- tional, West Sussex, United Kingdom) were used to measure the skinfold thickness from seven sites including: pectoralis major, triceps, mid-axillary region, subscapu- laris, suprailliac crest, abdomen, and thigh. The sum total of all measurements was recorded to the nearest 0.5 mm. Additionally, all measurements followed ACSM guide- lines [20]. Before the maximal exercise test, each subject was in- structed to lay supine for a 10minutes on an athletic training table in a dimly lit climate controlled laboratory. Room temperature and humidity were maintained at ap- proximately 22.2˚C and 50%, respectively. During this time, heart rate was assessed via ECG with the electrodes placed across the subject’s chest in a modified Lead II arrangement. The electrode leads were connected to a Biopac MP100 data acquisition system (Goletta, CA, USA). All variables were stored for offline analysis. The ECG recordings were visually inspected and any ectopic/ non-sinus beats were removed and replaced by the adja- cent normal cycle. If three or more ectopic beats were found within any ECG segment, the reading was ex- cluded from analysis. The last 5 minute period of the ECG recording was used for HRV analysis. The frequency domain analysis of HRV involved transforming the ECG into a power spectrum via fast Fourier transformation with a Hanning window by spe- cialized HRV software (Nevrokard version 11.0.2, Izola, Slovenia). The areas under the high frequency (0.15 - 0.40 Hz) and low frequency (0.04 - 0.14 Hz) components of the power spectrum were normalized. Normalized high frequency (HFnu) was recorded to represent para- sympathetic influence. Normalized low frequency to Open Access IJCM
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men 534 HFnu ratio (LF:HF) was recorded to represent sym- pathovagal balance. All HRV analyses were carried out in accordance with written established HRV guidelines [2]. All subjects completed a maximal graded exercise test using the Bruce protocol on a treadmill (Full Vision, Inc., Carrollton, TX). The concentration of expired oxygen and carbon dioxide gases were collected at the mouth with a pneumotach and analyzed using a calibrated Parvo Med- ics True One® 2400 metabolic cart (Sandy, UT). Maximal oxygen uptake was determined if two of the following criteria occurred: a plateau in VO2 (within ± 2 ml·kg−1·min−1) despite an increasing work rate; respiratory exchange ratio >1.15; heart rate within 10 beats of age predicted (220 − age) maximum or volitional fatigue. Once VO2max was achieved, intensity was reduced to a speed of 1.5 mph at 2% grade. HRR was determined as the difference between HRmax and the heart rate recorded at 1- (HRR1) and 2-minute (HRR2) into recovery. 2.3. Statistical Analysis Means and standard deviations were determined for all descriptive variables. The sample size was categorized into 2 groups based on whether they were below (AFG1, n = 20) or above (AFG2, n = 20) the value that corre- sponded to the referenced 50th percentile for VO2max for college-age men: i.e., 43.9 ml·kg−1·min −1 [20]. One-way analysis of variance (ANOVA) procedures were used to compare HRV (i.e., HFnu and LF:HF) and HRR (i.e., HRR1 and HRR2) between AFG1 and AFG2. Follow-up analysis of covariance (ANCOVA) proce- dures were performed to control for the potential con- founders of BMI, WC, and SF. Zero-order correlations were also used to determine the relationship between the studied variables. To clarify the influence of VO2max (as a continuous variable), BMI, WC, and SF on the variation in HFnu, LF:HF, HRR1, and HRR2, stepwise multiple regression procedures were used. The level of significance for all statistical tests was set at p < 0.05 (SPSS/PASW version 18.0, Somers, NY). 3. Results All participants successfully completed the testing pro- cedures. Descriptive statistics for the complete sample are presented in Table 1. Mean values and significant group differences for VO2max, BMI, WC, SF, HFnu, LF:HF, HRR1, and HRR2 are also displayed in Tab le 1. The one-way ANOVA procedures revealed significantly lower HFnu and significantly higher LF:HF values in AGF1 compared to AGF2 (p < 0.05, Ta ble 1 ). However, the one-way ANCOVA procedures showed that the dif- ferences in HFnu and LF:HF were not present when con- trolling for BMI (p = 0.22, p = 0.18, respectively), WC (p = 0.12, p = 0.11, respectively, Table 1), and SF (p = 0.51, p = 0.58, respectively, Table 1). Pearson product-moment correlations between all of the studied variables are shown in Table 2. VO2max did not correlate with any HRV or HRR parameter (p > 0.05). BMI and SF were the only anthropometric variables to significantly correlate with either HFnu or LF:HF (p < 0.05). Significant correlations were not found between any independent variable and HRR1 (p > 0.05). Only BMI and WC provided significant correlations with HRR2 (p < 0.05). The stepwise regression procedures showed that SF was the only variable to significantly account for the Table 1. Means and standard deviations of the studied variables within each group separately and the entire sam- ple. AFG1 (n = 20)AFG2 (n = 20) ALL (n = 40) VO2max 39.13 ± 3.15 50.53 ± 3.88* 44.83 ± 6.75 BMI 26.48 ± 3.70 24.57 ± 2.37 25.55 ± 3.23 WC 73.07 ± 23.1358.80 ± 25.47* 66.12 ± 25.04 SF 82.20 ± 27.3356.65 ± 20.72* 69.75 ± 27.28 HFnu 47.53 ± 6.56 52.25 ± 7.61*† 49.90 ± 7.41 LF:HF 0.83 ± 0.24 0.65 ± 0.27*† 0.74 ± 0.26 HRR1 21.60 ± 6.00 21.60 ± 6.58 21.60 ± 6.22 HRR2 44.45 ± 8.17 43.10 ± 10.26 43.77 ± 9.18 AFG1 = group of subjects with VO2max values below the 50th percentile normative value for age; AFG2 = group of subjects with VO2max values above the 50th percentile normative value for age; BMI = body mass index; WC = waist circumference; SF = sum of skinfold thickness; VO2max = maximal oxygen consumption; HFnu = normalized high frequency (HF) power; LF:HF = low frequency power to HF power ratio; HRR1 = heart rate recovery at 1-minute post-exercise; HRR2 = heart rate recovery at 2-minute post-exercise. *Significantly different from AFG1 (p < 0.05). †The effect for SFG disappeared when controlling for BMI and SF (each separately). Table 2. Zero-order correlation coefficients (r) showing the relationship between the var iables. VO2max BMI WC SF HFnu 0.27 −0.40† −0.22 −0.46† LF:HF −0.25 0.45† 0.29 0.54† HRR1 0.08 0.13 −0.09 0.12 HRR2 0.03 0.37† 0.44† 0.29 VO2max = maximal oxygen consumption, BMI = body mass index, WC = waist circumference, SF = sum of skinfold thickness from 7-site, HRR1 = 1-minute heart rate recovery, HRR2 = 2-minute heart rate recovery, HFnu = Normalized high frequency of heart rate variability, LF:HF = low frequency to high frequency ratio. †Significantly related, p < 0.01. Open Access IJCM
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men 535 variation of HFnu (R2 = 0.21, p < 0.05) and LF:HF (R2 = 0.30, p < 0.05). VO2max, BMI, or WC did not contribute to the variation in HFnu (p > 0.05) or LF:HF (p > 0.05) and were not included in the models. Stepwise regression also revealed that WC was the only variable to signifi- cantly account for the variation in HRR2 (R2 = 0.20). VO2max, BMI, or SF did not significantly contribute to the variation in HFnu (p > 0.05) and were not included in the model. 4. Discussion The chronic effects of impaired cardiac-autonomic con- trol exhibited as either lower HRV or delayed HRR can indicate the development of heart disease, hypertension, dyslipidemia, and type 2 diabetes [21,22]. These health conditions are prevalent at earlier ages in Blacks com- pared with other races [23-25]. Due to the discrepancies between races in cardiovascular disease risk factors, autonomic control and physical fitness [24,26,27] race- specific studies are needed. The purpose of this study was to determine whether referenced aerobic fitness groupings would reflect dif- ferences in HRV and HRR, independent of selected an- thropometric markers of body composition, and if the selected physical fitness parameters (i.e., VO2max, BMI, WC, and SF] were each significantly associated with the cardiac-autonomic variables in Black men. According to the American College of Sports Medi- cine [20], the 50th percentile for VO2max for the age group of the current sample is 43.9 ml·kg−1·min−1. The two groups were separated below (i.e., AFG1) and above (i.e., AFG2) this value. Though statistical significance was not found in HRR between groups, AFG1 had sig- nificantly lower HFnu and higher LF:HF compared to AFG2 indicating a less favorable autonomic balance in AFG1. However, the group differences in the HRV pa- rameters were not present when markers of body compo- sition were controlled for. In addition, BMI and SF were the only variables to be significantly related to HFnu and LF:HF. Alternatively, BMI and WC were the only vari- ables to significantly correlate to HRR2. The stepwise regression procedures demonstrated that SF accounted for 21% and 30% of the variation in HFnu and LF:HF, respectively, and that WC accounted for 20% of the va- riation in HRR2. Therefore, SF seems to be the strongest predictor of resting HRV, while WC is the strongest pre- dictor of HRR in Black men. When analyzed as a con- tinuous variable, the stepwise regression procedures ex- cluded VO2max as it did not significant relate to any HRV or HRR parameter. Previous investigations assessing the influence of aerobic fitness on cardiovascular-autonomic control have shown equivocal findings. Researchers suggest that train- ing-induced bradycardia experienced by endurance ath- letes is caused by the increased parasympathetic tone [28]. However, others had claimed that this phenomenon was due to intrinsic, rather than extrinsic factors [29]. Still, some studies have suggested that there may [5,30] or may not [31,32] be an independent association be- tween increases in aerobic fitness and enhanced HRR or HRV. Furthermore, there does not appear to be a signifi- cant difference in HRV and HRR between aerobically- trained and anaerobically-trained athletes [33,34]. As such, it seems reasonable to propose that other compo- nents of physical fitness may play a role in enhancing cardiovascular-autonomic control rather than just in- creased VO2max. Body composition is a parameter of physical fitness that appears to be independently linked to autonomic activity. Increased adiposity is thought to contribute to heightened sympathetic nervous activity at rest, while blunting metabo- and baro-reflex sensitivity during and following exercise [24,35,36]. Studies have shown that WC, BMI, and body fat percentage are each negatively associated with HRV and HRR [9,10,37]. Similar to the current study, Esco and colleagues [10] showed that SF explained the greatest variation of HRV and HRR when analyzed via stepwise regression. However, separating independent variables from their study, including VO2max, did not add statistical significance to either model. Inter- estingly though, the sample consisted of mostly White men [10]. The novelty of the current investigation highlights the relationship between selected markers of physical fitness and cardiovascular-autonomic modulation in Black men. We believe that this is an important area of research due to the higher prevalence of cardiac-related disorders in Blacks, and due to the discrepancies in physical fitness and cardiovascular autonomic control between races [13, 14,16,18,19]. Similar to other studies [10,18], it appears that the difference in HRV across groups based on VO2max in Black men may be due to the fitter subjects having a healthier body composition profile. Significant HRR differences were not found between AGF1 and AGF2. The post-exercise autonomic marker, HRR2, was significantly and independently related to WC, but not SF or VO2max. This result is at odds with previous research conducted by Esco et al. [10] who showed HRR to be significantly related to SF, but not WC in mainly White men. Conversely, Gutin et al. [18] showed that WC had a negative influence on sympa- thetic-to-parasympathetic balance in Black adolescents, but not compared to their White counterparts. Interest- ingly, some studies suggest a higher HRV profile and faster HRR post-exercise in Blacks compared to Whites, Open Access IJCM
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men 536 despite Blacks having lower levels of cardiovascular fit- ness and higher rates of obesity [18,38,39]. One way to interpret these paradoxical findings is that the relation- ship between body composition, aerobic fitness and car- diac-autonomic control is race-specific. Nevertheless, the current findings strengthen the usefulness of simple body composition measures in predicting cardiovascular dis- ease risk factors in Black men at any level of aerobic fitness. The age of the current sample should be considered when interpreting the results, as only apparently healthy, young adult Black men were analyzed. Aging has been shown to affect cardiovascular-autonomic control and physical fitness. More specifically, Blacks have been shown having a more favorable autonomic profile in younger years of age [18]. However, these patterns may become confounded with aging due to the influence and higher prevalence of obesity or markers of inflammation in Blacks [18,40,41]. Accordingly, similar investigations that include older aged subjects and other ethnic/racial groups are needed to better understand this relationship. In conclusion, this study provided a direct comparison of HRV and HRR in young Black men with differing levels of aerobic fitness. The results of the investigation suggested higher HRV with a higher level of aerobic fitness in Black men primarily because of the fitter group having a superior body composition profile compared to the lower fit group. Skinfold thickness was the greatest predictor of resting HRV. Heart rate recovery did not differ from high fit and low fit groups, but was signifi- cantly related to WC. The results of this study under- score the importance of body composition when explain- ing the relationship between physical fitness and cardio- vascular-autonomic control in young Black men. Ac- cording to these results, lifestyle interventions should be designed to improve aerobic fitness and body composi- tion to fully enhance cardiovascular-autonomic function to mitigate risk for an acute cardiac event. Additional research is needed to further define the relationship be- tween physical fitness and cardiovascular-autonomic mo- dulation, thus aiding clinicians to provide appropriate lifestyle modifications to lower at-risk populations for cardiovascular disease. REFERENCES [1] M. R. Esco, M. S. Olson, H. N. Williford, D. L. Blessing, D. Shannon and P. Grandjean, “The Relationship between Resting Heart Rate Variability and Heart Rate Recovery,” Clinical Autonomic Research, Vol. 20, No. 1, 2010, pp. 33-38. http://dx.doi.org/10.1007/s10286-009-0033-2 [2] A. J. Camm, M. Malik, J. T. Bigger, G. Breithardt, S. Cerutti, R. J. Cohen, P. Coumel, E. L. Fallen, H. L. Ken- nedy, R. E. Kleiger, F. Lombardi, A. Malliani, A. J. Moss, J. N. Rottman, G. Schmidt, P. J. Schwartz and D. H. Singer, “Heart Rate Variability: Standards of Measure- ment, Physiological Interpretation and Clinical Use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiol- ogy,” Circulation, Vol. 93, No. 5, 1996, pp. 1043-1065. [3] K. Imai, H. Sato, M. Hori, H. Kusuoka, H. Ozaki, H. Yokoyama, H. Takeda, M. Inoue and T. Kamada, “Va- gally Mediated Heart Rate Recovery after Exercise Is Accelerated in Athletes but Blunted in Patients with Chronic Heart Failure,” Journal of the American College of Cardiology, Vol. 24, No. 6, 1994, pp. 1529-1535. http://dx.doi.org/10.1016/0735-1097(94)90150-3 [4] C. R. Cole, E. H. Blackstone, F. J. Pashkow, C. E. Snader and M. S. Lauer, “Heart-Rate Recovery Immediately after Exercise as a Predictor of Mortality,” New England Jour- nal of Medicine, Vol. 341, No. 18, 1999, pp. 1351-1357. http://dx.doi.org/10.1056/NEJM199910283411804 [5] A. E. Aubert, B. Seps and F. Beckers, “Heart Rate Vari- ability in Athletes,” Sports Medicine, Vol. 33, No. 12, 2003, pp. 889-919. http://dx.doi.org/10.2165/00007256-200333120-00003 [6] M. Buchheit and C. Gindre, “Cardiac Parasympathetic Regulation: Respective Associations with Cardiorespira- tory Fitness and Training Load,” American Journal of Physiology—Heart and Circulatory Physiology, Vol. 291, No. 1, 2006, pp. H451-H458. http://dx.doi.org/10.1152/ajpheart.00008.2006 [7] P. Buch, J. Friberg, H. Scharling, P. Lange and E. Pres- cott, “Reduced Lung Function and Risk of Atrial Fibrilla- tion in the Copenhagen City Heart Study,” European Re- spiratory Journal, Vol. 21, No. 6, 2003, pp. 1012-1016. http://dx.doi.org/10.1183/09031936.03.00051502 [8] R. M. Millis, R. E. Austin, M. D. Hatcher, V. Bond, M. U. Faruque, K. L. Goring, B. M. Hickey and R. E. DeMeers- man, “Association of Body Fat Percentage and Heart Rate Variability Measures of Sympathovagal Balance,” Life Sciences, Vol. 86, No. 5, 2010, pp. 153-157. http://dx.doi.org/10.1016/j.lfs.2009.11.018 [9] E. Z. Campos, F. N. Bastos, M. Papoti, I. F. Freitas Jr., C. A. Gobatto and P. Balikian Jr., “The Effects of Physical Fitness and Body Composition on Oxygen Consumption and Heart Rate Recovery after High-Intensity Exercise,” International Journal of Sports Medicine, Vol. 33, No. 8, 2012, pp. 621-626. http://dx.doi.org/10.1055/s-0031-1295442 [10] M. R. Esco, H. N. Williford and M. S. Olson, “Skinfold Thickness Is Related to Cardiovascular Autonomic Con- trol as Assessed by Heart Rate Variability and Heart Rate Recovery,” Journal of Strength and Conditioning Re- search, Vol. 25, No. 8, 2011, pp. 2304-2310. http://dx.doi.org/10.1519/JSC.0b013e3181f90174 [11] S. B. Richards, M. Funk and K. A. Milner, “Differences between Blacks and Whites with Coronary Heart Disease in Initial Symptoms and in Delay in Seeking Care,” American Journal of Critical Care, Vol. 9, No. 4, 2000, pp. 237-244. [12] E. J. Bell, P. L. Lutsey, B. G. Windham and A. R. Folsom, Open Access IJCM
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men 537 “Physical Activity and Cardiovascular Disease in African Americans in Atherosclerosis Risk in Communities,” Me- dicine and Science in Sports and Exercise, Vol. 45, No. 5, 2013, pp. 901-907. http://dx.doi.org/10.1249/MSS.0b013e31827d87ec [13] M. Bopp, S. Wilcox, M. Laken, K. Butler, R. E. Carter, L. McClorin and A. Yancey, “Factors Associated with Phy- sical Activity among African-American Men and Women,” American Journal of Preventative Medicine, Vol. 30, No. 4, 2006, pp. 340-346. http://dx.doi.org/10.1016/j.amepre.2005.11.007 [14] C. J. Lavie, T. Kuruvanka, R. V. Milani, A. Prasad and H. O. Ventura, “Exercise Capacity in Adult African-Ameri- cans Referred for Exercise Stress Testing: Is Fitness Af- fected by Race?” CHEST Journal, Vol. 126, No. 6, 2004, pp. 1962-1968. http://dx.doi.org/10.1378/chest.126.6.1962 [15] D. R. Wagner and V. H. Heyward, “Measures of Body Composition in Blacks and Whites: A Comparative Re- view,” American Journal of Clinical Nutrition, Vol. 71, No. 6, 2000, pp. 1392-1402. [16] M. R. Carnethon, B. Sternfeld, K. Liu, D. R. Jacobs Jr., P. J. Schreiner, O. D. Williams, C. E. Lewis and S. Sidney, “Correlates of Heart Rate Recovery over 20 Years in a Healthy Population Sample,” Medicine and Science in Sports and Exercise, Vol. 44, No. 2, 2012, pp. 273-279. http://dx.doi.org/10.1249/MSS.0b013e31822cb190 [17] R. P. Sloan, M. H. Huang, S. Sidney, K. Liu, O. D. Wil- liams and T. Seeman, “Socioeconomic Status and Health: Is Parasympathetic Nervous System Activity an Inter- vening Mechanism?” International Journal of Epidemi- ology, Vol. 34, No. 2, 2005, pp. 309-315. http://dx.doi.org/10.1093/ije/dyh381 [18] B. Gutin, C. Howe, M. H. Johnson, M. C. Humphries, H. Snieder and P. Barbeau, “Heart Rate Variability in Ado- lescents: Relations to Physical Activity, Fitness, and Adi- posity,” Medicine and Science in Sports and Exercise, Vol. 37, No. 11, 2005, pp. 1856-1863. http://dx.doi.org/10.1249/01.mss.0000175867.98628.27 [19] X. Wang, J. F. Thayer, F. Treiber and H. Snieder, “Ethnic Differences and Heritability of Heart Rate Variability in African- and European-American Youth,” American Jour- nal of Cardiology, Vol. 96, No. 8, 2005, pp. 1166-1172. http://dx.doi.org/10.1016/j.amjcard.2005.06.050 [20] W. R. Thompson, N. F. Gordon and L. S. Pescatello, “ACSM’s Guidelines for Exercise Testing and Prescrip- tion,” 8th Edition, Lippincott Williams and Wilkins, Phi- ladelphia, 2010. [21] C. Voulgari, S. Pagoni, A. Vinik and P. Poirier, “Exercise Improves Cardiac Autonomic Function in Obesity and Diabetes,” Metabolism, Vol. 62, No. 5, 2012, pp. 609- 621. [22] J. S. Wu, Y. C. Yang, F. H. Lu, T. S. Lin, J. J. Chen, Y. H. Huang, T. L. Yeh and C. J. Chang, “Cardiac Autonomic Function and Insulin Resistance for the Development of Hypertension: A Six-Year Epidemiological Follow-Up Study,” Nutrition, Metabolism and Cardiovascular Dis- ease, 2013. [23] K. Bibbins-Domingo, M. J. Pletcher, F. Lin, E. Vitting- hoff, J. M. Gardin, A. Arynchyn, C. E. Lewis, O. D. Wil- liams and S. B. Hulley, “Racial Differences in Incident Heart Failure among Young Adults,” New England Jour- nal of Medicine, Vol. 360, No. 12, 2009, pp. 1179-1190. http://dx.doi.org/10.1056/NEJMoa0807265 [24] W. M. Sherman, A. L. Katz, C. L. Cutler, R. T. Withers and J. L. Ivy, “Glucose Transport: Locus of Muscle Insu- lin Resistance in Obese Zucker Rats,” American Journal of Physiology, Vol. 255, No. 3, 1988, pp. E374-E382. [25] D. R. Williams and J. Leavell, “The Social Context of Cardiovascular Disease: Challenges and Opportunities for the Jackson Heart Study,” Ethnicity and Disease, Vol. 22, No. 1, 2012, pp. S1-S14. [26] C. J. Lavie, T. Kuruvanka, R. V. Milani, A. Prasad and H. O. Ventura, “Exercise Capacity in Adult African-Ameri- cans Referred for Exercise Stress Testing: Is Fitness Af- fected by Race?” CHEST Journal, Vol. 126, No. 6, 2004, pp. 1962-1968. http://dx.doi.org/10.1378/chest.126.6.1962 [27] D. Liao, R. W. Barnes, L. E. Chambless, R. J. Simpson Jr., P. Sorlie and G. Heiss, “Age, Race, and Sex Differ- ences in Autonomic Cardiac Function Measured by Spec- tral Analysis of Heart Rate Variability—The ARIC Study,” American Journal of Cardiology, Vol. 76, No. 12, 1995, pp. 906-912. http://dx.doi.org/10.1016/S0002-9149(99)80260-4 [28] J. B. Carter, E. W. Banister and A. P. Blaber, “Effect of Endurance Exercise on Autonomic Control of Heart Rate,” Sports Medicine, Vol. 33, No. 1, 2003, pp. 33-46. http://dx.doi.org/10.2165/00007256-200333010-00003 [29] A. S. Scott, A. Eberhard, D. Ofir, G. Benchetrit, T. P. Dinh, P. Calabrese, V. Lesiuk and H. Perrault, “Enhanced Cardiac Vagal Efferent Activity Does Not Explain Train- ing-Induced Bradycardia,” Autonomic Neuroscience, Vol. 112, No. 1, 2004, pp. 60-68. http://dx.doi.org/10.1016/j.autneu.2004.04.006 [30] A. Aslani, A. Aslani, J. Kheirkhah and V. Sobhani, “Cardio- Pulmonary Fitness Test by Ultra-Short Heart Rate Vari- ability,” Journal of Cardiovascular Disease Research, Vol. 2, No. 4, 2011, pp. 233-236. http://dx.doi.org/10.4103/0975-3583.89808 [31] E. A. Byrne, J. L. Fleg, P. V. Vaitkevicius, J. Wright and S. W. Porges, “Role of Aerobic Capacity and Body Mass Index in the Age-Associated Decline in Heart Rate Vari- ability,” Journal of Applied Physiology, Vol. 81 No. 2, 1996, pp. 743-750. [32] B., Verheyden, B. O. Eijnde, F. Beckers, L. Vanhees and A. E. Aubert, “Low-Dose Exercise Training Does Not In- fluence Cardiac Autonomic Control in Healthy Sedentary Men Aged 55-75 Years,” Journal of Sports Science, Vol. 24, No. 11, 2006, pp. 1137-1147. http://dx.doi.org/10.1080/02640410500497634 [33] T. Otsuki, S. Maeda, M. Iemitsu, Y. Saito, Y. Tanimura, J. Sugawara, R. Ajisaka and T. Miyauchi, “Postexercise Heart Rate Recovery Accelerates in Strength-Trained Athletes,” Medicine and Science in Sports and Exercice, Vol. 39, No. 2, 2007, pp. 365-370. Open Access IJCM
Association of Body Composition and Aerobic Fitness on Heart Rate Variability and Recovery in Young-Adult Black Men Open Access IJCM 538 http://dx.doi.org/10.1249/01.mss.0000241647.13220.4c [34] D. J. Berkoff, C. B. Cairns, L. D. Sanchez and C. T. Moorman III, “Heart Rate Variability in Elite American Track-and-Field Athletes,” Journal of Strength and Con- ditioning Research, Vol. 21, No. 1, 2007, pp. 227-231. http://dx.doi.org/10.1519/00124278-200702000-00041 [35] K. Dipla, G. P. Nassis and I. S. Vrabas, “Blood Pressure Control at Rest and during Exercise in Obese Children and Adults,” Journal of Obesity, Vol. 2012, 2012, pp. 1-10. http://dx.doi.org/10.1155/2012/147385 [36] A. Figueroa, T. Baynard, B. Fernhall, R. Carhart and J. A. Kanaley, “Impaired Postexercise Cardiovascular Autono- mic Modulation in Middle-Aged Women with Type 2 Diabetes,” European Journal of Cardiovascular Preven- tion and Rehabilitation, Vol. 14, No. 2, 2007, pp. 237- 243. http://dx.doi.org/10.1097/HJR.0b013e32801da10d [37] F. Deniz, M. T. Katircibasi, B. Pamukcu, S. Binici and S. Y. Sanisoglu, “Association of Metabolic Syndrome with Impaired Heart Rate Recovery and Low Exercise Capac- ity in Young Male Adults,” Clincal Endocrinolgy, Vol. 66, No. 2, 2007, pp. 218-223. http://dx.doi.org/10.1111/j.1365-2265.2006.02711.x [38] M. R. Esco and M. S. Olson, “Racial Differences Exist in Cardiovascular Parasympathetic Modulation Following Maximal Exercise,” Journal of Applied Research, Vol. 10, No 1, 2010, pp. 24-31. [39] K. M. Flegal, M. D. Carroll, C. L. Ogden and L. R. Curtin, “Prevalence and Trends in Obesity Among US Adults, 1999-2008,” Journal of the American Medical Associa- tion, Vol. 303, No. 3, 2010, pp. 235-241. http://dx.doi.org/10.1001/jama.2009.2014 [40] D. S. Freedman, L. K. Khan, M. K. Serdula, D. A. Ga- luska and W. H. Dietz, “Trends and Correlates of Class 3 Obesity in the United States from 1990 through 2000,” Journal of the American Medical Association, Vol. 288, No. 14, 2002, pp. 1758-1761. http://dx.doi.org/10.1001/jama.288.14.1758 [41] K. S. Heffernan, S. Y. Jae, V. J. Vieira, G. A. Iwamoto, K. R. Wilund, J. A. Woods and B. Fernhall, “C-Reactive Protein and Cardiac Vagal Activity Following Resistance Exercise Training in Young African-American and White Men,” American Journal of Physiology-Regulatory, Inte- grative and Comparative Physiology, Vol. 296, No. 4, 2009, pp. R1098-R1105. http://dx.doi.org/10.1152/ajpregu.90936.2008
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