RESEARCH
PRESENTED AT 2008 AMERICAN COLLEGE OF SPORT MEDICINE MEETING
The Influence of Body Fat, Physical Activity and Cardiorespiratory Fitness on C-reactive Protein and Fibrinolysis in Females.
CJ Womack FACSM, CE Schubert, and JA Flohr. The Morrison-Bruce Center for the Promotion of Physical Activity for Girls and Women. Department of Kinesiology, MSC 2302. James Madison University. Harrisonburg, VA 22801.PURPOSE: Although it is well established that increased body fat, inactivity, and poor cardiorespiratory fitness are linked with cardiovascular disease and related risk factors, the relative importance of these parameters on C-reactive protein (CRP) and fibrinolysis have not been well established in females.
METHODS: Sixty females (mean age = 50.0 +/- 10.1 years) were evaluated for this study. Body density was assessed using dual energy x-ray absorptiometry (DEXA). Total weekly physical activity was assessed using a pedometer worn for a two week period. Cardiorespiratory fitness (VO2max) was assessed using a graded treadmill test to exhaustion. Fasting blood samples were obtained and serum CRP from these samples was completed at an external medical laboratory using a large particle amino assay. Plasma tPA antigen and PAI-1 activity were assessed using bio-functional immunosorbent assays for 44 subjects. Stepwise multiple regression was used to determine the independent associations between tPA, PAI-1, C-reactive protein and: fat mass, body fat percentage, total weekly steps and VO2max (ml/kg FFM/min).
RESULTS: The only variable that was successfully entered in the stepwise regression equations for all three risk factors was fat mass; which independently explained 41, 50, and 23 % of the variance in CRP, PAI-1 and tPA antigen respectively. Neither VO2max, nor physical activity was included in the regression equation for CRP and PAI-1, while tPA antigen was significantly predicted by a combination of: fat mass, age, VO2max, and body fat percentage (R = 0.68).
CONCLUSION: Results suggest that fat mass may be the primary controllable determinant of C-reactive protein and fibrinolysis in females. It is possible that the impact of physical activity and physical fitness on these risk factors is mediated by the resulting impact on body fat.
CURRENT RESEARCH PROJECTS BEING CONDUCTED/SUPPORTED BY THE CENTER
Vigorous Physical Activity in College Alumnae and Risk of Chronic Disease
Judith A. FlohrThe project is a descriptive study of JMU alumnae and non-alumnae who may or may not have engaged in vigorous physical activity during young adulthood (18 – 22 years of age) and a prospective cohort study of JMU alumnae. Initial data collection started October 21, 2004. New subjects (alumnae) will be tested on an annual basis. Follow-up testing of all subjects will be completed on an annual basis starting April 2008.
The purpose of this study is to assess the impact that vigorous physical activity engaged in early adulthood (18 – 22 years) has on a women’s lifestyle and risk for chronic disease later in life.
The Impact of Physical Activity on Non-Traditional Risk Factors in Women
Chris Womack
The Morrison-Bruce Center has started an ongoing study that evaluates the relationship between physical activity, physical fitness, and nutrition with traditional and non-traditional risk factors for cardiovascular disease. Participants are given an extensive health and fitness screening. This data will better elucidate the relationship between healthy behaviors and cardiovascular disease risk factors in women.
Caffeine and Bone Mineral Density
Sandra CubbageSeveral studies have been performed to determine if caffeine consumption has a negative impact on bone density. However, the findings have been mixed; with some studies observing a significant relationship and others suggesting no negative impact of caffeine on bone health. A particular gene has been observed to impact the rate at which caffeine is metabolized by the liver. In a prior study, caffeine users who expressed that gene a certain way had an elevated risk of cardiovascular disease, whereas participants with the form of the gene that caused them to metabolize caffeine rapidly had no such association. A women’s center study headed by Sandra Cubbage, a master’s student, is seeking to determine whether this same gene influences whether caffeine has a negative impact on bone health. Several females have had their bone density measured using the DEXA machine in the Human Performance Laboratory. These participants will be genotyped to determine whether they are fast or slow caffeine metabolizers and the fast vs. slow group will be compared as to the relationship between caffeine intake and bone density. This study is funded by a grant from the College of Integrated Science and Technology.
Gender differences in plantar pressure distribution
Sarah CebulskiWomen are more susceptible to overuse injuries and foot deformities than men and tend to have a wider forefoot, shorter arch length, and shorter metatarsals. Clinical studies have demonstrated hormone effects on ligament laxity and injury rate. ACL laxity, for example, increases with the increasing level of estrogen. Research has also shown the combination of mechanical loading and estrogen to decrease collagen and biglycan levels, possibly resulting in increased ligament injury in female athletes. There is virtually no research regarding how hormonal changes during the menstrual cycle affect plantar ligament elasticity and plantar pressure. I plan to study the changes in dynamic plantar pressure distribution at a walking speed among fatigued female athletes throughout their menstruation cycles.
Iron Deficiency in Female Athletes
Christy EasonIron deficiency is the most common single nutrient deficiency in the world, affecting between 20% and 50% of the world's population (DeMaeyer & Adiels-Tegman, 1985). In the United States, the incidence of iron deficiency without anemia among premenopausal women is estimated to range from 11% to 13% (Looker, Dallman, Carroll, Gunter, & Johnson, 1997). Women have lower iron stores than men because of iron loss during their reproductive years (Whitfield, Treloar, Zhu, Powell, & Martin, 2003). Menstruating women carry an increased risk for iron deficiency regardless of training status due to monthly blood loss (Akabas & Dolins, 2005). Iron loss during the menstrual cycle is approximately 0.5 to 0.6 mg/day (Clarkson & Haymes, 1995), corresponding to a median loss of 30ml of blood per cycle (Clarkson & Haymes, 1995).
The casual athlete who trains less than four hours week is no more likely to develop an iron deficiency than a sedentary person (Eichner, 1992). However, athletes who train six or more hours per week are at a greater risk of developing an iron deficiency. Because physical working capacity depends to a large extent on the adequacy of the oxygen transport system (Astrand & Barkve, 1970), decrement in this function could seriously impair one’s ability for maximum work. Endurance athletes are particularly prone to iron deficiency (Zoller & Vogel, 2004). Endurance athletes are known to experience sports anemia, which is a dilution of ferritin and hemoglobin due to the plasma volume expansion that occurs with training. In addition, Anderson and Barkve (Andersen & Barkve, 1970) have reported that iron-deficiency anemia impairs the working capacity of individuals by placing an increased load on their cardiorespiratory system. In anemia one potential means of compensating for the decrement in hemoglobin is by an increase in blood flow. This may be accomplished by an elevated heart rate and/or stroke volume (BISHOP, DONALD, & WADE, 1955), or a decrease in peripheral resistance (Varat, Adolph, & Fowler, 1972). The lifespan of red blood cells during intensive training is cut short, which leads to a need to produce more red blood cells faster (Smith, 1995).
Currently, studies have only investigated the effects of prolonged (minimum 4wks of supplementation) iron supplementation on blood iron levels and performance. The purpose of this study is to determine if one week of iron supplementation, during menstruation will affect serum ferritin and serum transferrin levels, and heart rate in female intercollegiate athletes during a 3-Minute YMCA step test.
The objectives of the study are to:
- Determine if there is a relationship between iron supplementation and serum iron markers
- Determine if there is a relationship between iron supplementation and heart rate during a 3-Minute YMCA step test.
- Determine if there is a relationship between iron supplementation and blood lactate
PRESENTED AT 2007 SOUTHEAST AMERICAN COLLEGE OF SPORT MEDICINE MEETING
Muscular Strength And Bone Mineral Density In Adult Females
Jamie K. Munnis, Judith A. Flohr, PhD, M. Kent Todd, PhD, FACSM. Morrison Bruce Center, James Madison University, Harrisonburg, VA 22807PURPOSE: The purpose of this study was to determine if there was a relationship between muscular strength and bone mineral density (BMD) values in adult women.
METHODS: Thirty-four females, aged 42-78 years participated in the study. Dual-energy x-ray absorptiometry (DXA) was used to determine bone mineral density (BMD) in the lumbar spine (LS) and right femoral neck (RFN). ACSM guidelines for 1-repetition maximum (1-RM) for bench press (BP)and leg press (LP)testing were used to determine upper (UBMS) and lower body muscular strength (LBMS), respectively.
RESULTS: There were no significant relationships between UBMS and LS or RFN. There were significant relationships among LBMS and RFN BMD (r=0.336, p=.024), and RFN T-score (r=0.379, p=0.012) and LBMS and lumbar BMD (r=0.302, p=.039), and lumbar T-score (r=0.308, p=0.036). When controlling for menopause, significant relationships were found among LBMS and RFN BMD (r=0.296,p=0.047), RFN T-score (r=0.362, p=0.019),lumbar BMD (r=0.296, p=0.019), and lumbar T-score (r=0.301, p=0.045). RFN BMD T-score indicated significant differences between pre and postmenopausal women (p=0.031) when not accounting for LBMS influence on the T-score. However, when the accounting for LBMS on T-score, that significant difference no longer existed (p(LP)= 0.019, p (menopause)=0.067).
CONCLUSIONS: Exercise prescriptions designed to increase lower body muscular strength may result in increased BMD for adult women. Similar studies including length of time in menopause are warranted.
PRESENTED AT THE 2007 NATIONAL CONFERENCE ON UNDERGRADUATE RESEARCH
The Influence Of Menopausal Status, Physical Activity And Hormone Replacement Therapy On A Woman’s Level Of C-Reactive Protein
Carolyn E. Schubert (Dr. Judith A. Flohr), Morrison Bruce Center, Department of Kinesiology, James Madison University, Harrisonburg, VA 22081.INTRODUCTION: Heart disease is the number one cause of death for women. C-reactive protein (CRP), a marker of inflammation, has been shown in some studies to be correlated with coronary heart disease and thus has become a novel risk factor for heart disease. The purpose of the study was to determine if there was a difference in CRP between premenopausal (PREM) and postmenopausal (POSTM) women and if relationships occurred between physical activity (PA) and CRP and physical fitness (VO2 max) and CRP.
METHODS: Fifty-four women (PREM=21, PERIM=8, POSTM =22,) had blood drawn that was analyzed for CRP, performed a graded exercise test on the treadmill to determine physical fitness (VO2 max). To determine PA participants wore a pedometer for two weeks and completed the International Physical Activity Questionnaire (IPAQ).
RESULTS: There was no difference in CRP between PREM and POSTM women; the PERIM women, however, had a mean CRP almost twice as high. Within the group of PREM women, no relationship existed between PA and CRP or VO2 max and CRP. Within the POSTM women, a non-significant trend was observed between PA and CRP and a significant relationship was observed between VO2 max and CRP.
CONCLUSION: The results indicate that physical fitness and to a lesser degree physical activity has a larger affect on CRP once a woman is postmenopausal. CRP levels may increase during menopause. Furthermore, the CRP levels observed in PERIM women highlight the importance conducting additional research involving appropriate numbers of women in order to accurately define their risk for heart disease and how it may be influenced by menopausal status.
ABSTRACTS PRESENTED AT 2006 MEETING OF THE AMERICAN COLLEGE OF SPORTS MEDICINE
Carbohydrate Supplementation Attenuates Blood Glucose Decreases In Pregnant Exerciser
Christine W. St. Laurent, Judith A. Flohr, Michael J. Saunders, FACSM & Connie L. Peterson, Department of Kinesiology, Morrison Bruce Center James Madison University, Harrisonburg, VAThe ACSM and ACOG recommend that healthy women, free of obstetrical complications participate in regular, moderately-intense physical activity throughout their pregnancies. However, a decrease in blood glucose (BG) is often observed with pregnant exercisers in their second and third trimesters when compared to non-pregnant controls.
PURPOSE: To determine the effect of carbohydrate (CHO) supplementation on blood glucose (BG) of pregnant exercisers during a 30-minute, moderate intensity, submaximal exercise session.
METHODS: Six pregnant participants, (maternal ages 30.16 ± 4.17 years and gestational ages 20.0 ± 9.13) completed two exercise sessions consisting of a 30-minute treadmill walk at 55-65% of their maximal heart rate. Participants were given a placebo drink (PD) (150 ml water with Crystal LiteTM given every 10 min) during one trial and a concentrated CHO gel during the other trial (10 g CHO with 150 ml water given every 10 min, for a total of 30 g CHO). BG and other metabolic variables were measured at 10-minute intervals before, during, and after the trials and analyzed using nonparametric K-related samples analysis and 2-related samples analysis statistical tests.
RESULTS: In both trials there was a significant decrease in BG from rest to 10 minutes, (PD: 74.94 ± 8.04 vs. 71.83 ± 6.64 mg/dl, p<0.05; CHO: 84.00 ± 20.45 vs. 69.78 ± 14.92 mg/dl, p<0.05) rest to 20 minutes, (PD: 74.94 ± 8.04 vs. 67.58 ± 14.92 mg/dl, p<0.05; CHO: 84.00 ± 20.45 vs. 68.73 ± 11.09 mg/dl, p<0.05) and a significant decrease from rest to 40 minutes in the PD trial only, (74.94 ± 8.04 vs. 67.55 ± 7.31 mg/dl, p<0.05). In the CHO trial, there was a significant increase in BG from 20-30 minutes, (68.73 ± 11.09 vs. 77.95 ± 8.70 mg/dl, p<0.05) and 30-40 minutes, (77.95 ± 8.70 vs. 93.20 ± 11.00 mg/dl, p<0.05). There were no significant differences in VO2, RER, or VE between trials.
CONCLUSION: It appears that during pregnancy, consuming a CHO supplement during a moderately intense, 30-minute exercise session helps prevent declines in BG that may occur. This intensity and duration of exercise are consistent with the guidelines from ASCM/ACOG for pregnant women.
Vigorous Physical Activity In College Alumnae And Risk Of Coronary Artery Disease
Jan E. Hart, Judith A. Flohr, M. Kent Todd, FACSM & Cara J. Sidman, Kaiser Permanente, Oakland, CA, James Madison University, Harrisonburg, VA, and University of Wisconsin-Whitewater, Whitewater, WI.
Physical activity is known to enhance various aspects of health and minimize the risk for chronic diseases. There is a lack of data on the impact vigorous physical activity engaged in during young adulthood has on a woman’s risk for coronary artery disease (CAD) later in life.
PURPOSE: to assess the impact that vigorous physical activity engaged in during young adulthood (18-22 years) has on a woman’s lifestyle and her risk for CAD later in life and compare the CAD risk levels of former collegiate athletes to non-collegiate athletes.
METHODS: Twenty-five females, thirteen former athletes (FATH mean age 53.31 ± 5.07) and 12 non-athletes (NATH mean age 51.42 ± 5.28) participated in the study. Physical characteristics and risk for CAD were measured, including age, height, weight, percent body fat, predicted oxygen uptake (PO2) blood pressure (BP), total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), blood glucose (BG), family history, smoking status, physical activity level, and body mass index (BMI). Risk for CAD was determined for all participants as the number of risk factors based on the ACSM guidelines. Then, using the ACSM risk stratification, each person was given a one if they were at low risk, two for moderate risk, and three for high risk, so that analysis could be performed (ACSM, 2000).
RESULTS: Individual t-tests for all variables were performed and no significant differences (p<0.05) were found between the FATH and NATH groups. When comparing the risk for CAD, the FATH had slightly less risk, although not a significant difference compared to the NATH. The FATH total risk was an average of 0.92 ± 1.12, while the NATH average was 1.00 ± 1.13 risk factors.
CONCLUSION: The results collected from a cohort of pre and postmenopausal women indicated that vigorous physical activity in young adulthood does not decrease the risk of CAD in the future. Benefits gained from physical activity in young adulthood did not appear to result in a reduced risk for CAD later in life.
