The association of physical activity with prediabetes/type 2 diabetes and cardiac autonomic function

Three separate studies were conducted to assess the association of physical activity with prediabetes/type 2 diabetes (pre/T2D) and cardiac autonomic function. The purpose of study 1 was to examine whether using both objectively (accelerometer) and subjectively (questionnaire) measured moderate- to vigorous-intensity physical activity (MVPA) and sedentary time (SED) improves the prediction of pre/T2D using data from the Framingham Heart Study (n=4200). Logistic regression was used to examine the odds ratio of pre/T2D in groups cross-classified by subjective and objective MVPA and SED. The findings demonstrated that low objectively measured MVPA appears more closely associated with pre/T2D risk compared to subjective measures, and there does not appear to be an additive effect of SED on pre/T2D risk after accounting for MVPA. The purpose of study 2 was to examine the effects of 3-6 months of aerobic, resistance, and combined aerobic and resistance exercise training on heart rate recovery (HRR) from three previously reported randomized trials (n=147). A repeated measures ANCOVA was used to examine differences in 1-, 2-, 3-, 4-, and 5-min HRR from pre- to post-intervention and compared to control adjusting for sex, Tanner stage, ethnicity, and training duration. The findings suggest that aerobic exercise training may be a more effective strategy for improving HRR in adolescents with overweight or obesity. The purpose of study 3 was to examine the association of MVPA or SED and pre/T2D with heart rate variability (HRV) in Hispanic adults using data from the Hispanic Community Health Study / Study of Latinos (n=11 209). Multiple linear regression models were used to examine differences in RMSSD and SDNN in groups cross-classified by MVPA or SED with pre/T2D, adjusting for age, body mass index, sex, education, nutrition, smoking status, alcohol use, cardiovascular disease, and MVPA or SED where appropriate. Having pre/T2D, regardless of MVPA or SED, was associated with lower RMSSD and SDNN. There was an association of high HRV with high MVPA in individuals without pre/T2D, but it did not translate to individuals with pre/T2D. The association of MVPA and SED with HRV in individuals with pre/T2D requires further investigation.