Resistance Training Augments Cerebral Blood Flow Pulsatility: Cross-Sectional Study

The effects of habitual resistance exercise training on cerebrovascular responses to lower body dynamic resistance exercise: A cross-sectional study

Dynamic resistance exercise (RE) produces sinusoidal fluctuations in blood pressure with simultaneous fluctuations in middle cerebral artery blood velocity (MCAv). Some evidence indicates that RE may alter cerebrovascular function. This study aimed to examine the effects of habitual RE training on the within-RE cerebrovascular responses. RE-trained (n = 15, Female = 4) and healthy untrained individuals (n = 15, Female = 12) completed four sets of 10 paced repetitions (15 repetitions per minute) of unilateral leg extension exercise at 60% of predicted 1 repetition maximum. Beat-to-beat blood pressure, MCAv and end-tidal carbon dioxide were measured throughout. Zenith, nadir and zenith-to-nadir difference in mean arterial blood pressure (MAP) and mean MCAv (MCAvmean) for each repetition were averaged across each set. Two-way ANOVA was used to analyse dependent variables (training × sets), Bonferroni corrected t-tests were used for post hoc pairwise comparisons. Group age (26 ± 7 trained vs. 25 ± 6 years untrained, P = 0.683) and weight (78 ± 15 vs. 71 ± 15 kg, P = 0.683) were not different. During exercise average MAP was greater for the RE-trained group in sets 2, 3 and 4 (e.g., set 4: 101 ± 11 vs. 92 ± 7 mmHg for RE trained and untrained, respectively, post hoc tests all P = < 0.012). Zenith MAP and zenith-to-nadir MAP difference demonstrated a training effect (P < 0.039). Average MCAvmean and MCAvmean zenith-to-nadir difference was not different between groups (interaction effect P = 0.166 and P = 0.459, respectively). Despite RE-trained individuals demonstrating greater fluctuations in MAP during RE compared to untrained, there were no differences in MCAvmean. Regular RE may lead to vascular adaptations that stabilise MCAv during RE.

Cerebrovascular adaptations to habitual resistance exercise with aging

Resistance training (RT) is associated with improved metabolism, bone density, muscular strength, and lower risk of osteoporosis, sarcopenia, and cardiovascular disease. Although RT imparts many physiological benefits, cerebrovascular adaptations to chronic RT are not well defined. Participation in RT is associated with greater resting peripheral arterial diameters, improved endothelial function, and general cardiovascular health, whereas simultaneously linked to reductions in central arterial compliance. Rapid blood pressure fluctuations during resistance exercise, combined with reduced arterial compliance, could lead to cerebral microvasculature damage and subsequent cerebral hypoperfusion. Reductions in cerebral blood flow (CBF) accompany normal aging, where chronic reductions in CBF are associated with changes in brain structure and function, and increased risk of neurodegeneration. It remains unclear whether reductions in arterial compliance with RT relate to subclinical cerebrovascular pathology, or if such adaptations require interpretation in the context of RT specifically. The purpose of this narrative review is to synthesize literature pertaining to cerebrovascular adaptations to RT at different stages of the life span. This review also aims to identify gaps in the current understanding of the long-term impacts of RT on cerebral hemodynamics and provide a mechanistic rationale for these adaptations as they relate to aging, cerebral vasculature, and overall brain health.

Effects of Greater Central Arterial Stiffness on Cardiovagal Baroreflex Sensitivity in Resistance-Trained Men

Background

Compared with age-matched untrained men, resistance-trained men who have undergone long duration training (> 2 years) at a high frequency (> 5 days/week) may be lower cardiovagal baroreflex sensitivity (BRS) because of central arterial stiffening. Therefore, the purpose of this study was to examine the effect of greater central arterial stiffness in resistance-trained men on cardiovagal BRS in a cross-sectional study to compare resistance-trained men with age-matched untrained men.

Methods

This cross-sectional study included resistance-trained men (n = 20; age: 22 ± 3; body mass index: 26.7 ± 2.2) and age-matched untrained men (control group: n = 20; age: 25 ± 2; body mass index: 23.7 ± 2.4). The β-stiffness index and arterial compliance were assessed at the right carotid artery using a combination of a brightness mode ultrasonography system for the carotid artery diameter and applanation tonometry for the carotid blood pressure. And, the cardiovagal BRS was estimated by the slope of the R–R interval and systolic blood pressure during Phase II and IV of Valsalva maneuver (VM). The participants maintained an expiratory mouth pressure of 40 mmHg for 15 s in the supine position.

Results

The β-Stiffness index was significantly higher in the resistance-trained group than in the control group (5.9 ± 1.4 vs. 4.4 ± 1.0 a.u., P < 0.01). In contrast, the resistance-trained group had significantly lower arterial compliance (0.15 ± 0.05 vs. 0.20 ± 0.04 mm²/mmHg, P < 0.01) and cardiovagal BRS during Phase IV of VM (9.0 ± 2.5 vs. 12.9 ± 5.4 ms/mmHg, P < 0.01) than the control group and. Moreover, cardiovagal BRS during Phase IV of VM was inversely and positively correlated with the β-stiffness index (r = − 0.59, P < 0.01) and arterial compliance (r = 0.64, P < 0.01), respectively.

Conclusion

Resistance-trained group had greater central arterial stiffness and lower cardiovagal BRS Phase IV compared with control group. Moreover, the central arterial stiffening was related to cardiovagal BRS Phase IV. These results suggest that greater central arterial stiffness in resistance-trained men may be associated with lower cardiovagal BRS.

Trial Registration University hospital Medical Information Network (UMIN) in Japan, UMIN000038116. Registered on September 27, 2019.

The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise

Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.

Long-term Pingju Opera Training Induces Plasticity Changes in Cerebral Blood Flow: An Arterial Spin Labelling MRI Study

Professional Pingju actors have been shown to exhibit practice-induced plastic changes in spontaneous regional brain activity; however, whether these changes are present in resting-state regional cerebral blood flow (CBF) remains largely unclear. Here, twenty professional Pingju opera actors and 20 age-, sex-, and handedness-matched untrained subjects were recruited, and resting-state CBF maps were obtained by using a three-dimensional pseudocontinuous arterial spin labelling sequence. Voxel-based comparisons of the CBF maps between the two groups were performed with two-sample t-tests, and correlation analyses between the CBF changes and years of training in the actor group were conducted. In addition, the CBF connectivity between regions with CBF alterations and the whole brain was computed and compared between the two groups. Compared with untrained subjects, the actors showed significantly higher CBF in the right inferior temporal gyrus, right middle temporal gyrus, left temporal pole, and left inferior frontal gyrus, whereas significantly lower CBF was not found in the actor group (voxel-level uncorrected p < 0.001, cluster-level family-wise error corrected p < 0.05). Furthermore, there was no correlation between the mean CBF values from significantly different clusters and the years of training, and no significant alterations in CBF connectivity were found in the actor group. Overall, these results provided preliminary evidence that neural plastic changes in CBF are present in professional Pingju opera actors, which may correspond to specific experiences associated with Pingju opera training.