Slow-paced breathing is a clinical intervention used to increase heart rate variability (HRV). The practice is made more accessible via cost-free smartphone applications like Elite HRV. We investigated whether Elite HRV can accurately measure and augment HRV via its slow-paced breathing feature. Twenty young adults completed one counterbalanced cross-over protocol involving 10 min each of supine spontaneous (SPONT) and paced (PACED; 6 breaths·min⁻¹) breathing while RR intervals were simultaneously recorded via a Polar H10 paired with Elite HRV and reference electrocardiography (ECG). Individual differences in HRV between devices were predominately skewed, reflecting a tendency for Elite HRV to underestimate ECG-derived values. Skewness was typically driven by a limited number of outliers as median bias values were ≤1.3 ms and relative agreement was ≥very large for time-domain parameters. Despite no significant bias and ≥large relative agreement for frequency-domain parameters, limits of agreement (LOAs) were excessively wide and tended to be wider during PACED for all HRV parameters. PACED significantly increased low-frequency power (LF) for Elite HRV and ECG, and between-condition differences showed very large relative agreement. Elite HRV-guided slow-paced breathing effectively increased LF values, but it demonstrated greater precision during SPONT and in computing time-domain HRV.

Urinary concentrations of several acute kidney injury (AKI) biomarkers increased after completing the 2023 Western States Endurance Run; however, there were no changes in renal blood flow in a subset of runners. When normalized to creatinine, several AKI biomarkers, including IGFBP7·TIMP2 (an FDA-approved biomarker of AKI), remained elevated. Notably, finishing the race euhydrated appeared to have a protective effect, mitigating increases in IGFBP7·TIMP2.

Aging is associated with decreased muscle strength and power. Power is particularly important for maintaining the independence of older adults when performing activities of daily living. The countermovement jump has been identified as a reliable and safe method to assess lower extremity power across the lifespan. The purpose of this investigation was to study sex differences and age-related changes in countermovement jump peak power among masters weightlifters with the secondary purpose of comparing results to previous reports of community and masters athletes. Female (n = 63, 39 to 70 yrs, med (56 yrs)) and male (n = 39, 35 to 86 yrs, med (59 yrs)) participants of the 2022 World Masters Championships completed three maximal effort countermovement jump repetitions following a dynamic warm-up. Vertical ground reaction forces were recorded, and peak power normalized to body mass was calculated. Results indicated significant age-related peak power among weightlifters, with the decline being significantly more pronounced in males than females. Female weightlifters exhibited less age-related decline compared to normative data as well as the other Master athlete comparison cohorts (short and long-distance runners), whereas the males demonstrated similar age-related declines as the comparison cohorts. While the female weightlifters in the current study generally demonstrated the least age-related declines in CMJ peak power of the comparative literature, the male weightlifters showed similar age-related decline rates.

Slow-paced breathing during heart rate variability biofeedback is used to augment cardiac-autonomic modulation. This practice has become widely available with the advent of cost-free smartphone applications such as Elite HRV. However, whether Elite HRV can effectively augment heart rate variability (HRV) and accurately measure HRV during its guided slow-paced breathing feature has not been determined. Therefore, 20 healthy young adults (13 M/8 F) completed a single-visit counterbalanced cross-over protocol involving 10 min each of supine spontaneous (SPONT) and paced (PACED; 6 breaths•min-1) breathing while RR intervals were simultaneously recorded via a Polar H10 paired with Elite HRV and criterion electrocardiography (ECG). HRV values automatically computed by Elite HRV were compared with ECG-derived values filtered and computed using standardized methodology. PACED significantly increased low frequency power (LF) for Elite HRV and ECG (Ps ≤ 0.003) and between-condition difference values for Elite HRV and ECG LF were very largely correlated (Lin’s concordance correlation = 0.73). However, absolute LF values differed, and inconsistent effects were observed for other HRV parameters. For validity, agreement between devices for mean RR was acceptable irrespective of condition (Ps ≥ 0.06, coefficient of variation ≤ 2.2%). Conversely, agreement weakened for time and frequency domain parameters during SPONT and was further weakened for each during PACED. Findings revealed that although slow-paced breathing via Elite HRV effectively increased LF HRV, it weakened agreement with the criterion for conventional HRV parameters (excluding mean RR) relative to spontaneous breathing.

This is the first study to assess the effects of mild hypohydration on acute kidney injury biomarkers in young and older female adults. Mild hypohydration altered acute kidney injury biomarker concentrations in both age groups, with no observed age-related differences, contrasting with male studies that show an age-related decline. These findings highlight the need for targeted research on potential sex-related differences in kidney function decline with aging.

Aim: Regular exercise is beneficial, but more exercise may not always benefit cardiovascular health (extreme exercise hypothesis). This is concerning, because ultramarathon participation is growing, but previous work on cardiovascular health among ultramarathon runners is equivocal. Prior work has not examined this population’s age-related differences in prognostic cardiovascular health metrics. Purpose: Measure brachial and central BP and arterial stiffness (carotid-to-femoral pulse wave velocity [cfPWV]) among ultramarathon runners. Methods: We measured supine BP and cfPWV (SphygmoCor-XCEL) among 71 athletes (16 female/55 male; body mass index: 22.6 ± 1.8 kg/m ² ) 1–3 days before they competed in the 161-km Western States Endurance Run. We present data as mean ± SD. We analyzed the relation between age and central BP, brachial BP, and cfPWV with nonlinear (quadratic) regression. Results: There was a significant curvilinear relation between age (46 ± 10; range 26–69 years) and central (116 ± 8 mmHg, R ² = 0.18, P = 0.02) but not brachial (129 ± 9 mmHg, R ² = 0.06, P = 0.11) systolic BP. There was a significant relation between age and central (79 ± 7 mmHg, R ² = 0.24, P < 0.001) and brachial (78 ± 7 mmHg, R ² = 0.23, P < 0.001) diastolic BP. There was a significant (R ² = 0.31, P = 0.02) curvilinear relation between age and cfPWV (6.5 ± 1.0m/s). Average brachial systolic BP differed by + 1.4 mmHg/decade, and 86% of athletes had a cfPWV below age-predicted (mean difference: − 0.9 ± 1.0 m/s). Conclusions: These are among the first data to characterize central BP and arterial stiffness across a wide age range of ultramarathon runners. Further work is needed to determine the longitudinal changes associated with training for and competing in ultramarathons.