The purpose of the current study was to determine the concurrent validity of the Elite HRV smartphone application when calculating heart rate variability (HRV) metrics in reference to an independent software criterion. A total of 5 minutes of R–R interval and natural log of root mean square of the successive differences (lnRMSSD) resting HRV data were simultaneously collected using two Polar H10 heart rate monitors (HRMs) in both the seated and supine positions from 22 participants (14 males, 8 females). One H10 HRM was paired with a Polar V800 watch and one with the Elite HRV application. When no artifact correction was applied, significant, but small, differences in the lnRMSSD data were observed between the software in the seated position (p = 0.022), and trivial and nonstatistically significant differences were observed in the supine position (p = 0.087). However, significant differences (p > 0.05) in the lnRMSSD data were no longer identifiable in either the seated or the supine positions when applying Very Low, Low, or Automatic artifact-correction filters. Additionally, excellent agreements (ICC3,1 = 0.938 − 0.998) and very strong to near-perfect (r = 0.889 − 0.997) relationships were observed throughout all correction levels. The Elite HRV smartphone application is a valid tool for calculating resting lnRMSSD HRV metrics.
1 June 2020 in The American Journal of Clinical Nutrition
Conflicting results on associations between dietary quality and bone have been noted across populations, and this has been understudied in Puerto Ricans, a population at higher risk of osteoporosis than previously appreciated. To compare cross-sectional associations between 3 dietary quality indices [Dietary Approaches to Stop Hypertension (DASH), Alternative Health Eating Index (AHEI-2010), and Mediterranean Diet Score (MeDS)] with bone outcomes. Participants (n = 865-896) from the Boston Puerto Rican Osteoporosis Study (BPROS) with complete bone and dietary data were included. Indices were calculated from validated food frequency data. Bone mineral density (BMD) was measured using DXA. Associations between dietary indices (z-scores) and their individual components with BMD and osteoporosis were tested with ANCOVA and logistic regression, respectively, at the lumbar spine and femoral neck, stratified by male, premenopausal women, and postmenopausal women. Participants were 59.9 y ± 7.6 y and mostly female (71%). Among postmenopausal women not taking estrogen, DASH (score: 11-38) was associated with higher trochanter (0.026 ± 0.006 g/cm2, P <0.001), femoral neck (0.022 ± 0.006 g/cm2, P <0.001), total hip (0.029 ± 0.006 g/cm2, P <0.001), and lumbar spine BMD (0.025 ± 0.007 g/cm2, P = 0.001). AHEI (score: 25-86) was also associated with spine and all hip sites (P <0.02), whereas MeDS (0-9) was associated only with total hip (P = 0.01) and trochanter BMD (P = 0.007) in postmenopausal women. All indices were associated with a lower likelihood of osteoporosis (OR from 0.54 to 0.75). None of the results were significant for men or premenopausal women. Although all appeared protective, DASH was more positively associated with BMD than AHEI or MeDS in postmenopausal women not taking estrogen. Methodological differences across scores suggest that a bone-specific index that builds on existing indices and that can be used to address dietary differences across cultural and ethnic minority populations should be considered.
Firefighters have a sustained risk for experiencing a sudden cardiac event after completing a fire call. Heart rate recovery (HRR) can be utilized to characterize autonomic nervous system (ANS) recovery and has been linked to cardiac events. Research suggests that body composition influences post-exercise HRR responses in non-firefighter populations. The purpose of this study was to examine the influence of body mass index (BMI), waist circumference (WC), and percent body fat (BF) on the HRR response of firefighter recruits. BMI (kg·m−2), WC (cm), and BF (%) data from 57 firefighter recruits were collected. HRR (b·min−1) data were collected at completion (HR0), as well as 15 (HR15), 30 (HR30), 45 (HR45), 60 (HR60), 120 (HR120), and 180 (HR180) seconds following a submaximal step test, and commonly utilized clinical HRR indices were calculated (ΔHRR30, ΔHRR60, ΔHRR120, and ΔHRR180). After controlling for sex, linear mixed regression models did not identify significant interactions between body composition (ps > 0.05) and HRR response across time. However, significant (ps < 0.05) indirect semi-partial correlations were identified between BF and ΔHRR30 (rsp = −0.31) and ΔHRR60 (rsp = −0.27), respectively. Reducing overall BF (vs. BMI or WC) should be prioritized to improve the post-exercise ANS recovery of firefighter recruits.