Effect of Heart Rate Reserve on Prefrontal Cortical Activation While Dual-Task Walking in Older Adults

Hypertension is considered a risk factor for cardiovascular health and non-amnestic cognitive impairment in older adults. While heart rate reserve (HRR) has been shown to be a risk factor for hypertension, how impaired HRR in older adults can lead to cognitive impairment is still unclear. The objective of this study was to examine the effects of HRR on prefrontal cortical (PFC) activation under varying dual-task demands in older adults. Twenty-eight older adults (50–82 years of age) were included in this study and divided into higher (n = 14) and lower (n = 14) HRR groups. Participants engaged in the cognitive task which was the Modified Stroop Color Word Test (MSCWT) on a self-paced treadmill while walking. Participants with higher HRR demonstrated increased PFC activation in comparison to lower HRR, even after controlling for covariates in analysis. Furthermore, as cognitive task difficulty increased (from neutral to congruent to incongruent to switching), PFC activation increased. In addition, there was a significant interaction between tasks and HRR group, with older adults with higher HRR demonstrating increases in PFC activation, faster gait speed, and increased accuracy, relative to those with lower HRR, when going from neutral to switching tasks. These results provide evidence of a relationship between HRR and prefrontal cortical activation and cognitive and physical performance, suggesting that HRR may serve as a biomarker for cognitive health of an older adult with or without cardiovascular risk.

Physical Activity in the Workplace: Does Just Working Meet Activity Recommendations?

Background: The physical activity (PA) health paradox hypothesizes that occupational physical activity (OPA) and leisure time PA have differential cardiovascular health effects due to increased cardiovascular load without adequate recovery; however, research describing worker PA lacks high-quality objective OPA measurement. This study aimed to objectively describe PA profiles of men reporting high OPA and make comparisons to aerobic PA and OPA recommendations. Methods: Male food service, material moving, health care, or maintenance workers wore activity (ActiGraph® and activPAL®) and heart rate monitors for 7 days. Participants recorded work, non-work, and sleep times in a diary. PA was operationalized as time spent in sedentary behavior, upright time, light, moderate, vigorous, and moderate-to-vigorous PA during work and non-work hours. PA profiles were described and compared with Centers for Disease Control and Prevention aerobic PA guidelines (≥21.4 minute/day) and OPA recommendations (<30 minute/hour upright and intensity of <30% heart rate reserve). Findings: Nineteen male workers (68% White, age = 46.6±7.9 years) were more active on workdays than non-workdays (sedentary: 492.3 vs. 629.7 minute/day; upright: 462.4 vs. 325.2 minute/day; moderate-to-vigorous PA: 72.4 vs. 41.5 minute/day, respectively; all p < .05). Most participants (17/19) achieved aerobic PA guidelines across all days with more achieving on workdays (19/19) than non-workdays (13/19). OPA often exceeded recommended limits with participants accumulating 39.6±12.2 minutes/work hour upright and 30.3±25.9% of working time >30% heart rate reserve. Conclusions/Application to Practice: Male workers reporting high OPA typically met aerobic PA guidelines but exceeded recommended OPA limits. The long-term health implications of such activity profiles should be investigated.

Relative Vigorous-Intensity Physical Activity Predicts Brain Microstructural Changes in Older Adults

Physical activity especially at moderate-to-vigorous intensity may preserve brain structure in old age. However, current findings are cross-sectional and rely on absolute intensity. This study aimed to examine whether relative or absolute vigorous-intensity physical activity (VPA) predicts brain microstructural changes. We analyzed 260 initially cognitively normal and well-functioning participants(age=70.5yrs) who had VPA data via ActiHeart and longitudinal brain microstructure by DTI(follow-up=3.7yrs). Associations of VPA with microstructural changes were examined using linear mixed-effects models, adjusted for demographics. Each SD higher relative VPA defined by heart rate reserve (i.e. 21 min/day) was significantly associated with less decline in memory-related microstructural integrity, including mean diffusivity of entorhinal cortex and parahippocampal gyrus and fractional anisotropy of uncinate fasciculus and cingulum-hippocampal part, and not executive/motor-related microstructure. Absolute VPA was not associated with microstructural markers. Among well-functioning older adults, participating in VPA defined by heart rate reserve may predict less brain microstructural decline in memory-related areas.

Responsiveness and Relationships of Shooting Performance to On-Ice Physical Performance Tests

The aim of this investigation was to quantify the acute effects of the execution of the physical performance tests within the ice hockey-specific complex test (IHCT) on shooting performance. Thirty-four professional male ice hockey players with an average of 6.9 years of playing experience were recruited. The slap shot (SS) was found to accelerate the puck with a higher speed and greater precision. After the IHCT, the maximum puck speed of successful goal shots decreased considerably (p < 0.001, d > 1.5). The puck speed percentage decrement after the IHCT did not differ between the SS (6.1, SD = 4.4, −5.5–17.9) and the wrist shot (WS, 6.0, SD = 3.5, −0.9–12.2, p = 0.86, d = 0.03). The magnitude of puck speed reduction in the WS was inversely related to the functional heart rate reserve (r = −0.44, p = 0.02) and the blood lactate elimination rate (r = −0.43, p < 0.02). The linear and COD speed tests on-ice resulted in a higher amount of successful goal shots. These findings highlight the interaction of intense on-ice testing and goal-shooting performance.

Additive prognostic value of coronary flow and heart rate reserve during vasodilator stress echocardiography in hypertrophic cardiomyopathy

Background Coronary flow velocity reserve (CFVR) and heart rate reserve (HRR) during vasodilator stress echocardiography (SE) assess coronary microvascular function and cardiac sympathetic reserve respectively. Both CFVR and HRR can be impaired in hypertrophic cardiomyopathy (HCM). Objectives To evaluate the prognostic value of CFVR and HRR during vasodilator SE in HCM. Methods We enrolled 244 HCM patients (age=51±15 years, 116 men) studied with vasodilator SE from 1999 to 2019 in 5 certified centers. Stress modality was either adenosine (Ado, 0.14 mg/kg/min in 2', n=171) or dipyridamole (Dip, 0.84 mg/kg in 6', n=73). Left ventricular outflow tract obstruction was present at rest in 80 patients (33%). We assessed CFVR in left anterior descending coronary artery (by TTE in 225, and TEE in 19 patients) and HRR (peak/rest heart rate). Abnormal values of HRR were based on receiver operating characteristics for Ado and Dip separately calculated. All patients completed the follow-up. Results CFVR was 2.17±0.46 for Dip and 2.13±0.43 for Ado (p=ns); HRR was 1.36±0.19 for Dip and 1.10±0.16 for Ado (p&lt;0.001). An abnormal CFVR (&lt;2.0 for both Ado and Dip) was present in 28 patients for Dip and 73 for Ado (38% vs 43%, p=ns). An abnormal HRR (≤1.34 for Dip and ≤1.03 for Ado) was present in 39 patients for Dip and in 70 patients for Ado (53% vs 41%, p=ns). During a median follow-up of 67 months (interquartile range: 29–103 months), 97 spontaneous events occurred in 71 patients: 29 all-cause deaths, 32 new hospital admission for acute heart failure, 3 sustained ventricular tachycardias, 32 atrial fibrillations and 1 heart transplantation. Event rate was 2.5%/year in patients with normal CFVR and HRR, 4.7%/year in patients with only one abnormal criterion and 10.9%/year in patients with abnormal responses of both criteria (see figure). At multivariate analysis, abnormality of both CFVR and HRR (Hazard ratio 4.033, 95% CI 1.863–8.729, p&lt;0.001) was independent predictor of events. Conclusions A reduced CFVR and blunted HRR during vasodilator SE identify distinct phenotypes and show independent value in predicting outcome in HCM patients. FUNDunding Acknowledgement Type of funding sources: None. Figure 1. Kaplan-Meier spontaneous event-free survival curves based on HRR and CFVR. Kaplan-Meier survival curves (considering spontaneous events) in patients stratified with the abnormal HRR and/or CFVR. Number of patients at risk per year is shown.

COUNTERPOINT: Theoretical and Empirical Basis for Equating Heart Rate Reserve with V̇o2 Reserve

ABSTRACT In 1998, the American College of Sports Medicine recommended the use of % heart rate reserve (HRR) and % oxygen consumption reserve (V̇o2R) for providing equivalent exercise intensities based on limited research regarding the relationship of HR and V̇o2 from rest to maximal exercise. It further emphasized that the percentage of aerobic capacity, or %V̇o2max, does not provide equivalent intensities to %HRR and that this discrepancy is greater for individuals with lower levels of cardiorespiratory fitness, especially at low exercise intensities. This point/counterpoint examines additional research to evaluate these relationships.

Coronary Flow, Left Ventricular Contractile and Heart Rate Reserve in Non-Ischemic Heart Failure

Background: Left ventricular contractile reserve (LVCR), coronary flow velocity reserve (CFVR), and heart rate reserve (HRR) affect outcome in heart failure (HF). They can be simultaneously measured during dipyridamole stress echocardiography (DSE). Aim: To assess the value of comprehensive DSE in patients with non-ischemic HF. Methods: We evaluated 610 patients with HF, no history of coronary artery disease, and no inducible regional wall motion abnormalities: 270 patients with preserved ejection fraction (≥50%), 146 patients with mid-range ejection fraction (40–49%), and 194 patients with reduced ejection fraction (<40%). All underwent DSE (0.84 mg/kg in 6’) in 7 accredited laboratories. We measured LVCR (abnormal value ≤ 1.1), CFVR in left anterior descending artery (abnormal value: ≤2.0), and HRR (peak/rest heart rate; abnormal value: ≤1.22). All patients were followed up. Results: Abnormal CFVR, LVCR, and HRR occurred in 29%, 45%, and 47% of patients, respectively (p < 0.001). After a median follow-up time of 20 months (interquartile range: 12–32 months), 113 hard events occurred in 105 patients with 41 deaths, 8 myocardial infarctions, 61 admissions for acute HF, and 3 strokes. The annual mortality rates were 0.8% in 200 patients with none abnormal criteria, 1.8% in 184 patients with 1 abnormal criterion, 7.1% in 130 patients with 2 abnormal criteria, 7.5% in 96 patients with 3 abnormal criteria. Conclusion: Abnormal LVCR, CFVR, and HRR were frequent during DSE in non-ischemic HF patients. They target different pathophysiological vulnerabilities (myocardial function, coronary microcirculation, and cardiac autonomic balance) and are useful for outcome prediction.