The Effects of Aquatic Exercise on Cognitive Function: Systematic Review
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
Academic Editor: Gerhard Litscher
Special Issue: Research of Exercise and Cognitive Function
Received: February 07, 2019 | Accepted: March 19, 2019 | Published: March 21, 2019
OBM Integrative and Complementary Medicine 2019, volume 4, issue 1 doi:10.21926/obm.icm.1901018
Recommended citation: Loprinzi PD. The Effects of Aquatic Exercise on Cognitive Function: Systematic Review. OBM Integrative and Complementary Medicine 2019; 4(1): 018; doi:10.21926/obm.icm.1901018
© 2019 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.
Accumulating research demonstrates that both acute and chronic exercise have protective and therapeutic effects on cognitive function [1,2,3,4]. These evaluated exercise modalities often include land-based walking, jogging and/or cycling activities. Less research, however, has evaluated the extent to which aquatic-based exercise may improve and/or preserve cognitive function [5,6]. This is a notable area of interest for several reasons. First, this provides individuals with an alternative modality to exercise. Secondly, aquatic exercise is less weight-bearing than traditional land-based exercise, and thus, for co-morbid and elderly populations, this may be an attractive alternative to allow for engagement in safe, health-enhancing exercise. The purpose of the present study, written as a brief report, was to systematically evaluate the literature to evaluate the extent to which aquatic exercise is associated with cognitive function. To my knowledge, no such systematic review exits.
2. Materials and Methods
Studies were identified using electronic databases, including PubMed, PsychInfo, Sports Discus and Google Scholar. Articles were retrieved up to January 3, 2019 (no restriction was placed on how far back the study was published). The search terms, including their combinations, were: exercise, physical activity, aquatic, aqua, water, water-based, swimming, cognition, cognitive function, memory, and executive function.
To be eligible for inclusion in this review, studies had to be published in English and among humans; employ a cross-sectional, prospective or experimental design; include a measure of aquatic or water-based physical activity/exercise as the independent variable; and the outcome variable could be any neural, cognitively-related biomarker, or cognitive outcome measure. The computerized searches include 5,123 articles. In total, 13 articles met the above-stated criteria.
Records were managed via an extraction table that included study parameters of author, sample characteristics, study design, exercise protocol, outcome variable (cognition), and main findings. Each evaluated article that met the study criteria was read in its entirety, with these study parameters retrieved from each article.
Table 1 displays the extraction table for the 13 studies. Among the 13 studies, 12 were experimental studies, whereas one was a case study . Among the 12 experimental studies, 9 were conducted among middle-age to older adults, with 2 occurring among children/adolescents [7,8] and 1 among young adults . Samples included healthy individuals, as well as those with intellectual disabilities , ADHD (attention deficit hyperactive disorder) , fibromyalgia [10,11], mild cognitive impairment , Alzheimer’s disease , and multiple sclerosis .
The chronic aquatic exercise programs ranged from 7 days to 6 months, whereas several studies employed a single bout of aquatic exercise [9,14]. Most of the aquatic exercise programs focused on aquatic exercise alone, whereas some evaluated it in combination with cranial electrotherapy stimulation , cognitive training [15,16], and land-based exercise training . The cognitive outcomes varied, including global measures of cognition (e.g., MMSE; Mini-Mental State Exam), executive function, attention, learning and memory, language fluency, cognitive communication, cerebral oxygenation, and biomarkers (e.g., BDNF (brain-derived neurotrophic factor), VEGF (vascular endothelial growth factor), IGF-1 (insulin-like growth factor-1)) of cognitive function. Among the 13 studies, all 13 demonstrated beneficial cognitive effects from exercise. This included chronic aquatic exercise-induced improvements in global cognition, executive function, attention, learning and memory, cognitively-related biomarkers (e.g., BDNF) and cerebral oxygenation. For the two acute aquatic studies, listening errors, via an auditory vigilance task, was reduced when participants were emerged in chest-deep water, when compared to on land.
The motivation for the present paper was a result of: 1) prior work demonstrating beneficial effects of exercise on cognitive function [1,2,3,4], 2) emerging work demonstrating beneficial effects of aquatic exercise on psychological well-being [18,19], and 3) the implications (e.g., feasibility, less weight-bearing) of aquatic exercise for health promotion purposes. The main finding of the present review was that, chronic aquatic exercise training appears to be effective in enhancing various biomarkers and cognitive outcomes. Further, short-term immersion in chest-deep water may also enhance cognition.
With regard to short-term immersion in chest-deep water, and as discussed elsewhere , water immersion may improve cerebral blood flow. Hydrostatic pressure may stimulate mechanoreceptors whose impulses may produce presynaptic inhibition or excitation of interneuron pathways. Further, partial aquatic immersion may also increase parasympathetic drive via a baroreflex from increased central blood volume and stroke volume.
Regarding chronic aquatic exercise, beneficial effects on cognition may arise from the acute benefits of water immersion as well as from enhancement effects from chronic engagement in exercise. Regarding the latter, and as discussed elsewhere [20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35], chronic exercise may have broad effects on cognition via alterations in angiogenesis, gliogenesis, and neurogenesis. Further, chronic exercise-induced enhancement of cardiorespiratory fitness may also play an important role in improving cognitive function .
In conclusion, this brief systematic review highlights the beneficial effects of acute water immersion and chronic aquatic exercise engagement in subserving cognitive function. These beneficial effects appear to occur across multiple populations, including children, adolescents, young adults and older adults with various conditions, such as Multiple Sclerosis, Alzheimer’s disease, and fibromyalgia. Additional work is needed that carefully compares chest deep water immersion vs. aquatic exercise, in an effort to determine whether it is water immersion or aquatic exercise that is driving the observed cognitive enhancement effects.
Table 1 Extraction table of the evaluated human studies.
No funding was used to prepare this manuscript.
Paul D. Loprinzi did all work for this paper.
The author has declared that no competing interests exist.
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