Na Zhu

University of Minnesota Twin Cities, Minneapolis, MN, USA

Are you Na Zhu?

Claim your profile

Publications (4)25.17 Total impact

  • Article: Cardiovascular health through young adulthood and cognitive functioning in midlife.
    [show abstract] [hide abstract]
    ABSTRACT: OBJECTIVE: A study was undertaken to examine the association between overall cardiovascular health as recently defined by the American Heart Association in young adulthood to middle age and cognitive function in midlife. Overall ideal cardiovascular health incorporates 7 metrics, including the avoidance of overweight or obesity, a healthful diet, nonsmoking, and physical activity, total cholesterol, blood pressure, and fasting glucose at goal levels. METHODS: This analysis of the Coronary Artery Risk Development in Young Adults study, a multicenter community-based study with 25 years of follow-up, included 2,932 participants aged 18 to 30 years at baseline (year 0) who attended follow-up examinations at years 7 and 25. Cardiovascular health metrics were measured at each examination. The Digit Symbol Substitution Test (DSST), modified Stroop test, and Rey Auditory Verbal Learning Test (RAVLT) were completed at year 25. RESULTS: A greater number of ideal cardiovascular metrics in young adulthood and middle age were independently associated with better cognitive function in midlife (p for trend < 0.01, for all). Specifically, each additional ideal metric was associated with 1.32 more symbols on the DSST (95% confidence interval [CI] = 0.93 - 1.71), a 0.77-point lower interference score on the Stroop test (95% CI=-1.03 to -0.45), and 0.12 more words on the RAVLT (95% CI = 0.04 to 0.20). Participants who had ≥5 ideal metrics at a greater number of the 3 examinations over the 25-year period exhibited better performance on each cognitive test in middle age (p for trend < 0.01, for all). INTERPRETATION: Ideal cardiovascular health in young adulthood and its maintenance to middle age is associated with better psychomotor speed, executive function, and verbal memory in midlife. Ann Neurol 2013;
    Annals of Neurology 12/2012; · 11.09 Impact Factor
  • Article: Fat mass modifies the association of fat-free mass with symptom-limited treadmill duration in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.
    [show abstract] [hide abstract]
    ABSTRACT: The assessment of fat mass and fat-free mass in relation to the symptom-limited maximal exercise duration (Max(dur)) of a treadmill test allows for insight into the association of body composition with treadmill performance potential. We investigated the complex associations between fat mass and fat-free mass and Max(dur) in a population setting. The Max(dur) of a graded exercise treadmill test and body composition by dual-energy X-ray absorptiometry were estimated in 2413 black and white men and women aged 38-50 y from the Coronary Artery Risk Development in Young Adults (CARDIA) cohort. The mean Max(dur) was ≈7.5 s shorter per kilogram of fat mass in both men and women and independent of fat-free mass, height, race, television watching, physical activity, systolic blood pressure, lung function, and education. Fat mass modified the association of fat-free mass with the Max(dur) (2-way interaction P < 0.001), and the interaction was stronger in women than in men. In men in the lowest fat-mass quartile, the Max(dur) was 1.3 s longer per kilogram of fat-free mass and was 0.5 s shorter per kilogram of fat-free mass in the highest fat-mass quartile. In contrast, in women with the least fat mass, the Max(dur) was 2.7 s longer per kilogram of fat-free mass and was 2.8 s shorter per kilogram of fat-free mass in the highest fat-mass quartile. The Max(dur) was negatively related to fat mass. Fat-free mass in obese people contributed little to the treadmill performance potential as assessed by the Max(dur), although the contribution of fat-free mass was positive in thinner people.
    American Journal of Clinical Nutrition 06/2011; 94(2):385-91. · 6.67 Impact Factor
  • Article: Longitudinal examination of age-predicted symptom-limited exercise maximum HR.
    [show abstract] [hide abstract]
    ABSTRACT: To estimate the association of age with maximal HR (MHR). Data were obtained from the Coronary Artery Risk Development in Young Adults (CARDIA) study. Participants were black and white men and women aged 18-30 yr in 1985-1986 (year 0). A symptom-limited maximal graded exercise test was completed at years 0, 7, and 20 by 4969, 2583, and 2870 participants, respectively. After exclusion, 9622 eligible tests remained. In all 9622 tests, estimated MHR (eMHR, bpm) had a quadratic relation to age in the age range of 18-50 yr, eMHR = 179 + 0.29 x age - 0.011 x age(2). The age-MHR association was approximately linear in the restricted age ranges of consecutive tests. In 2215 people who completed tests of both years 0 and 7 (age range = 18-37 yr), eMHR = 189 - 0.35 x age; and in 1574 people who completed tests of both years 7 and 20 (age range = 25-50 yr), eMHR = 199 - 0.63 x age. In the lowest baseline body mass index (BMI) quartile, the rate of decline was 0.24 bpm*yr(-1) between years 0 and 7 and 0.51 bpm*yr(-1) between years 7 and 20, whereas in the highest baseline BMI quartile, there was a linear rate of decline of approximately 0.7 bpm.yr for the full age range of 18-50 yr. Clinicians making exercise prescriptions should be aware that the loss of symptom-limited MHR is much slower in young adulthood and more pronounced in later adulthood. In particular, MHR loss is very slow in those with the lowest BMI younger than 40 yr.
    Medicine and science in sports and exercise 08/2010; 42(8):1519-27. · 3.71 Impact Factor
  • Article: Longitudinal Examination of Age-Predicted Symptom-Limited Exercise Maximum Heart Rate.
    [show abstract] [hide abstract]
    ABSTRACT: PURPOSE:: To estimate the association of age with maximal heart rate (MHR). METHODS:: Data were obtained in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Participants were black and white men and women aged 18-30 in 1985-86 (year 0). A symptom-limited maximal graded exercise test was completed at years 0, 7, and 20 by 4969, 2583, and 2870 participants, respectively. After exclusion 9622 eligible tests remained. RESULTS:: In all 9622 tests, estimated MHR (eMHR, beats/minute) had a quadratic relation to age in the age range 18 to 50 years, eMHR=179+0.29*age-0.011*age. The age-MHR association was approximately linear in the restricted age ranges of consecutive tests. In 2215 people who completed both year 0 and 7 tests (age range 18 to 37), eMHR=189-0.35*age; and in 1574 people who completed both year 7 and 20 tests (age range 25 to 50), eMHR=199-0.63*age. In the lowest baseline BMI quartile, the rate of decline was 0.20 beats/minute/year between years 0-7 and 0.51 beats/minute/year between years 7-20; while in the highest baseline BMI quartile there was a linear rate of decline of approximately 0.7 beats/minute/year over the full age of 18 to 50 years. CONCLUSION:: Clinicians making exercise prescriptions should be aware that the loss of symptom-limited MHR is much slower at young adulthood and more pronounced in later adulthood. In particular, MHR loss is very slow in those with lowest BMI below age 40.
    Medicine and science in sports and exercise 02/2010; · 3.71 Impact Factor