Cerebral Blood Flow Responses to Aquatic Treadmill Exercise

Impact of Land Versus Water Environments on Orthostatic Hypotension in Older Adults: A Randomized Crossover Study

BACKGROUND/OBJECTIVES

Orthostatic hypotension (OH) is a common condition among older adults that increases the risk of falls. The study objectives are to determine the influence of distinct environments (water vs. land) on OH and the consequent effects of walking in these environments in older adults. Additionally, we aimed to assess the differences in response between two groups: older adults with OH and those without OH.

METHODS

A randomized crossover design was utilized including one session involving water walking and the other session involving land walking, with a 1- to 3-day washout period. Orthostatic hemodynamic measurements were obtained before, immediately after, and 2 hr after a 15-min walking session. Two subgroups were formed for analysis: participants with OH (n = 14, 81 ± 7 years) and participants without OH (n = 11, 84 ± 7 years).

RESULTS

Compared with the land environment, an 86% reduction in the frequency of OH episodes was noted when the older adults were immersed in water. This reduction was accompanied by greater mean arterial pressure, while participants without OH showed no such changes. The frequency of OH episodes was similar when assessed immediately after emerging from the pool following water-based walking or after land-based walking. All participants exhibited elevated mean arterial pressure immediately after water-based walking, but not after land-based walking. Two hours after walking, all participants demonstrated similar mean arterial pressure and frequency of OH episodes, regardless of the environment.

CONCLUSIONS

Water immersion resulted in a substantial reduction in the frequency of OH episodes among older adults. Additionally, the frequency of OH episodes was not affected by prior walking exercise in either environment. Significance/Implication: These findings underscore the safety and potential advantages of water-based exercise for older adults dealing with OH.

The effects of water temperature on cerebral blood flow during aquatic exercise

PURPOSE

Recent studies suggest that episodic increases in cerebral blood flow (CBF) may contribute to the improvement in brain health associated with exercise training. Optimising CBF during exercise may enhance this benefit. Water immersion in ~ 30-32 °C augments CBF at rest and during exercise; however, the impact of water temperature on the CBF response has not been investigated. We hypothesised that cycle ergometry in water would increase CBF compared to land-based exercise, and that warm water would attenuate the CBF benefits.

METHODS

Eleven young heathy participants (nine males; 23.8 ± 3.1 yrs) completed 30 min of resistance-matched cycle exercise in three separate conditions; non-immersion (Land), 32 °C and 38 °C water immersion up to the level of the waist. Middle cerebral artery velocity (MCAv), blood pressure, and respiratory measures were assessed throughout the exercise bouts.

RESULTS

Core temperature was significantly higher in the 38 °C immersion than 32 °C (+ 0.84 ± 0.24 vs + 0.04 ± 0.16, P < 0.001), whilst mean arterial pressure was lower during 38 °C exercise compared to Land (84 ± 8 vs 100 ± 14 mmHg, P < 0.001) and 32 °C (92 ± 9, P = 0.03). MCAv was higher in 32 °C immersion compared to the Land and 38 °C conditions throughout the exercise bout (68 ± 10 vs 64 ± 11 vs 62 ± 12 cm/s, P = 0.03 and P = 0.02, respectively).

CONCLUSION

Our findings suggest that cycle exercise in warm water attenuates the beneficial impact of water immersion on CBF velocity due to redistribution of blood flow to subserve thermoregulatory demand. Our findings suggest that, whilst water-based exercise can have beneficial effects on cerebrovascular function, water temperature is a key determinant of this benefit.

Nordic Walking in Water on Cerebrovascular Reactivity and Cognitive Function in Elderly Patients with Type 2 Diabetes

INTRODUCTION

Aquatic Nordic walking (ANW) is a novel whole-body low-impact exercise that can be practiced by a variety of older adults with chronic conditions. However, its efficacy on several aspects of health is largely unknown.

PURPOSE

This study aimed to determine the effects of regular ANW on glycemic control and vascular function in older adults with type 2 diabetes and mild cognitive impairment.

METHODS

Thirty-three older adults with type 2 diabetes age 60-75 yr were randomly allocated to nonexercising control ( n = 17) or ANW ( n = 17) groups. Nordic walking was performed in a pool at water temperature of 34°C-36°C, three times per week for 12 wk.

RESULTS

Measures of functional physical fitness including chair stand, timed up and go, chair sit and reach, reach and back scratch, and 6-min walk test scores were all improved after ANW (all P < 0.05). Plasma glucose, glycosylated hemoglobin, and homeostasis model assessment of insulin resistance decreased (all P < 0.05) in ANW. Vascular reactivity as assessed by brachial flow-mediated dilation increased, and arterial stiffness as assessed by brachial-ankle pulse wave velocity decreased in ANW (all P < 0.05). No significant changes were observed in the control group. Middle cerebral artery pulsatility index decreased with ANW under normocapnia condition ( P < 0.05). Cerebrovascular conductance increased with ANW under hypercapnia condition. Montreal Cognitive Assessment score increased in the ANW group ( P < 0.001). Changes in Montreal Cognitive Assessment scores were positively associated with corresponding changes in brain-derived neurotrophic factor ( r = 0.540, P = 0.031).

CONCLUSIONS

Nordic walking in water was a safe and effective innovative exercise modality to improve glycemic control, vascular function, physical fitness, cerebrovascular reactivity, and cognitive function in older adults with type 2 diabetes.

Effect of Acute Cardiovascular Exercise on Cerebral Blood Flow: A Systematic Review

A single bout of cardiovascular exercise can have a cascade of physiological effects, including increased blood flow to the brain. This effect has been documented across multiple modalities, yet studies have reported mixed findings. Here, we systematically review evidence for the acute effect of cardiovascular exercise on cerebral blood flow across a range of neuroimaging techniques and exercise characteristics. Based on 52 studies and a combined sample size of 1,174 individuals, our results indicate that the acute effect of cardiovascular exercise on cerebral blood flow generally follows an inverted U-shaped relationship, whereby blood flow increases early on but eventually decreases as exercise continues. However, we also find that this effect is not uniform across studies, instead varying across a number of key variables including exercise characteristics, brain regions, and neuroimaging modalities. As the most comprehensive synthesis on the topic to date, this systematic review sheds light on the determinants of exercise-induced change in cerebral blood flow, a necessary step toward personalized interventions targeting brain health across a range of populations.

Non-pharmacological interventions for vascular health and the role of the endothelium

The most common non-pharmacological intervention for both peripheral and cerebral vascular health is regular physical activity (e.g., exercise training), which improves function across a range of exercise intensities and modalities. Numerous non-exercising approaches have also been suggested to improved vascular function, including repeated ischemic preconditioning (IPC); heat therapy such as hot water bathing and sauna; and pneumatic compression. Chronic adaptive responses have been observed across a number of these approaches, yet the precise mechanisms that underlie these effects in humans are not fully understood. Acute increases in blood flow and circulating signalling factors that induce responses in endothelial function are likely to be key moderators driving these adaptations. While the impact on circulating factors and environmental mechanisms for adaptation may vary between approaches, in essence, they all centre around acutely elevating blood flow throughout the circulation and stimulating improved endothelium-dependent vascular function and ultimately vascular health. Here, we review our current understanding of the mechanisms driving endothelial adaptation to repeated exposure to elevated blood flow, and the interplay between this response and changes in circulating factors. In addition, we will consider the limitations in our current knowledge base and how these may be best addressed through the selection of more physiologically relevant experimental models and research. Ultimately, improving our understanding of the unique impact that non-pharmacological interventions have on the vasculature will allow us to develop superior strategies to tackle declining vascular function across the lifespan, prevent avoidable vascular-related disease, and alleviate dependency on drug-based interventions.

Evidence-Based Aquatic Therapy Guidelines for Parkinson's Disease: An International Consensus Study

BACKGROUND

Aquatic therapy is one therapy option for people living with Parkinson's disease (PD). However, the optimal prescription, dosage, and delivery remain unclear.

OBJECTIVE

i) To generate consensus statements, ii) to establish evidence-based clinical practice aquatic therapy guidelines for PD.

METHODS

Seventy-three international experts were invited to participate in a 3-step modified Delphi study. Gaps in the aquatic therapy evidence, patient preferences, and stakeholder engagement were considered when developing the initial list of 43-statements identified by the research development group. Practice experts rated each statement on an 11-point Likert scale. Consensus for inclusion was set at a priori of ≥70% of respondents scoring an item ≥7. Two rounds of Delphi questionnaires were completed online, and the expert comments were analyzed using content analysis. An online consensus meeting with an expert subgroup (n = 10) then advised on the guideline's acceptability and debated items until consensus for inclusion was reached.

RESULTS

Fifty experts participated in the Delphi round one (83% response rate) and 45 in round two (90% response rate), representing 15 countries. In round one, 35 statements met the criteria for consensus. Content analysis informed the revised statements in round two, where 12 of the remaining 16 statements met consensus. The final agreed aquatic therapy guidelines include key information about dosage, content, safety, contraindications, and the optimal aquatic therapy delivery throughout the disease course.

CONCLUSION

Stakeholders, including international practice experts, informed a rigorous evidence-based approach to integrate the best available evidence, patient preferences, and practice expertise to inform these guidelines.

The Impact of 6-Month Land versus Water Walking on Cerebrovascular Function in the Aging Brain

INTRODUCTION

To examine the hypothesis that exercise training induces adaptation in cerebrovascular function, we recruited 63 older adults (62 ± 7 yr, 46 females) to undertake 24 wk of either land walking or water walking, or participate in a nonexercise control group. This is the first multi-interventional study to perform a comprehensive assessment of cerebrovascular function in response to longer term (6-month) training interventions, including water-based exercise, in older healthy individuals.

METHODS

Intracranial blood flow velocities (middle cerebral artery (MCAv) and posterior cerebral artery) were assessed at rest and in response to neurovascular coupling, hypercapnic reactivity, and cerebral autoregulation.

RESULTS

We observed no change in resting MCAv in response to either training intervention (pre vs post, mean (95% confidence interval), land walking: 65 (59-70) to 63 (57-68) cm·s-1, P = 0.33; water walking: 63 (58-69) to 61 (55-67) cm·s-1, P = 0.92) compared with controls and no change in neurovascular coupling (land walking: P = 0.18, water walking: P = 0.17). There was a significant but modest improvement in autoregulatory normalized gain after the intervention in the water-walking compared with the land-walking group (P = 0.03). Hypercapnic MCAv reactivity was not different based on exercise group (land: P = 087, water: P = 0.83); however, when data were pooled from the exercise groups, increases in fitness were correlated with decreases in hypercapnic reactivity (r2 = 0.25, P = 0.003).

CONCLUSIONS

Although exercise was not associated with systematic changes across multiple domains of cerebrovascular function, our data indicate that exercise may induce modest changes in autoregulation and CO2 reactivity. These findings should encourage further studies of the longer-term implications of exercise training on cerebrovascular health.

Community aquatic therapy for Parkinson's disease: an international qualitative study

PURPOSE

To explore the opinions of people living with Parkinson's disease about access to and participation in community aquatic therapy.

METHODS

Focus groups and individual interviews were conducted with people living with Parkinson's disease in Ireland (n = 24) and Australia (n = 10). All discussions were audio-recorded, transcribed verbatim, and thematically analysed.

RESULTS

Four main themes were identified. Primarily, participants were optimistic about their reasons for choosing aquatic therapy and found it beneficial to their health and well-being. Optimal components of aquatic therapy identified were access to individually tailored aquatic programs, completed as a minimum once a week, at a moderate to high-intensity level, and guided by a credentialed instructor. Fear was a significant barrier for a small proportion of participants and was linked to water competence, past experiences, and fall risk associated with the aquatic environment. Participants identified a strong need for education and increased awareness about aquatic therapy benefits to promote greater engagement.

CONCLUSION

Aquatic therapy is a popular exercise choice for people with Parkinson's disease, especially in the early to middle disease stages. Considering the views of people living with Parkinson's disease can aid the design and implementation of interventions and future aquatic research internationally.Implications for RehabilitationAquatic therapy is emerging as an effective physiotherapy approach for managing motor and non-motor symptoms in Parkinson's disease.Little is known regarding community-based aquatic therapy programs from the perspectives of people living with Parkinson's disease internationally.People with Parkinson's disease may benefit from timely information about the unique benefits, prerequisites, and local aquatic therapy facilities to promote greater uptake of aquatic programs.Tailored aquatic therapy interventions delivered within a group setting by a credentialed healthcare professional may increase long-term adherence.

Aquatic Therapy in Contemporary Neurorehabilitation: An Update

Aquatic therapy has been used extensively in a number of neurologic diseases and pathologies. This review describes disease-specific rehabilitative applications for this population. Recent research has offered scientific support for use in common neurological diseases that are part of rehabilitative practice, and very recent findings may create even firmer support for its use in these as well as other conditions. Stroke, Parkinsonism, and multiple sclerosis are areas that have recently received a significant number of published studies. Dementia is another area that has been more recently studied and received basic science support. Cerebral palsy has also had recent supportive evidence published. Available literature is reviewed to create a more evidence-based support for the use of aquatic therapy in neurorehabilitation.

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.

Swimming-related effects on cerebrovascular and cognitive function

Both acute and regular exercise influence vascular and cognitive function. Upright aquatic exercise increases mean middle cerebral artery blood velocity (MCAvmean ) and has been suggested as favorable for cerebrovascular adaptations. However, MCAvmean has not been reported during swimming. Thus, we examined the cerebrovascular and cognitive effects of swimming. Ten land-based athletes (22 ± 5 years) and eight swimmers (19 ± 1 years) completed three cognitive tasks and four conditions that were used to independently and collectively delineate the swimming-related factors (i.e., posture, immersion, CO2 retention [end-tidal CO2 ; PETCO2 ], and motor involvement). Measurements of MCAvmean and PETCO2 were taken throughout each condition. Prone posture increased MCAvmean by 11% (P < 0.01 vs. upright land). Water immersion independently increased MCAvmean when upright (12%; P < 0.01) but not prone (P = 0.76). The consequent rise in PETCO2 during head-out, breast-stroke swimming (50% heart rate range) independently increased MCAvmean by 14% (P < 0.01), while the motor involvement of swimming per se did not significantly change MCAvmean (P = 0.32). While accounting for sex, swimmers had ~17% lower MCAvmean during all rest conditions (P ≤ 0.05). However, in a subset of participants, both groups had similar internal carotid artery diameters (P = 0.99) and velocities (P = 0.97). Water immersion per se did not alter cognition (P ≥ 0.15), but 20 min of moderate-intensity swimming improved visuomotor performance by 4% (P = 0.03), regardless of athlete group (P = 0.12). In conclusion, breast-stroke swimming increased MCAvmean mostly due to postural and PETCO2 effects, with minimal contributions from water immersion or motor activity. Lastly, swimming improved cognitive functioning acutely, regardless of athlete group. Future research should explore the chronic effects of swimming on cerebrovascular function and cognition, particularly in aging.