AUTHOR
By Traci Pantuso, ND
Adjunct Faculty, Research Investigator, Bastyr University, Seattle
SUMMARY POINTS
- The authors of this feasibility study wanted to establish criteria to measure the effects of swimming on a variety of emotional responses, including anger, depression, and esteem.
- An analysis of the data determined that both pool-based swimming and swimming at sea may improve mood and well-being in swimmers.
- Both open-water swimming and pool-based swimming are exercises that meet the recommended 150 minutes of moderate-to-vigorous physical activity per week.
- Much more research needs to be performed to understand whether there are benefits of open-water swimming compared to pool-based swimming or types of land-based activities, such as jogging or other sports.
SYNOPSIS: In a nonrandomized prospective cohort study to demonstrate feasibility, participants showed significant increases in positive mood and well-being as well as a reduction in negative mood states during both pool-based and sea-based swimming lessons.
SOURCE: Massey H, Kandala N, Davis C, et al. Mood and well-being of novice open water swimmers and controls during an introductory outdoor swimming programme: A feasibility study. Lifestyle Med 2020;1:e12.
The authors of this study were interested in determining whether outdoor swimming improves mental health, something suggested by anecdotal evidence.1 It also has been hypothesized that exercise in natural environments may be associated with a greater decrease in the risk of poor mental health compared to indoor environments.2 Furthermore, participants engaging in outdoor swimming have reported that these experiences were transformative, connecting, and reorientating.
The authors also wanted to know whether there were changes in mood that were immediate (acute) or delayed (chronic) because a previous study did not measure immediate changes after a swimming workout.3 To study this question, the authors designed a nonrandomized prospective cohort study that was reviewed and approved by the University of Portsmouth Science Faculty Ethics Committee.
There were two groups, the swimming group and the control group. Participants were recruited from the paying customers of the Brighton Swimming School and Portsmouth Outdoor Swimming as a convenience sample. Sixty-four participants were enrolled in the study, which took place in the United Kingdom. There were 57 women and seven men with an average age of 43 ± 10 years.
The control group consisted of 22 people that were family and friends of the participants who were there supporting the swimmers at each of the swim locations. Coached one-hour sessions were offered each week for 10 weeks, running from April to July 2018 in Brighton, United Kingdom. A similar course was run in Portsmouth, United Kingdom, from April to July 2019.
The first three weeks of the study were conducted in pools to build the confidence needed to swim outdoors, to explain what additional equipment swimmers may have needed, and to show participants how to put on and swim in a wetsuit. This was followed by seven weeks of coached outdoor swimming. Participants wore wetsuits and fully participated in the sea swims, and they self-determined how long to stay in depending on weather and sea conditions. The participants acting as the control group remained on the swimming pool balcony away from the pool during those sessions and on the beach for the sea swim sessions.
To measure mood and well-being changes in the participants, the authors used the abbreviated Profile of Mood States (POMS) questionnaire and the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS).
The abbreviated POMS questionnaire is a 40-item questionnaire that measures mood across seven subscales (tension, fatigue, depression, anger, confusion, esteem, and vigor) on a five-point scale ranging from “not at all” (0) to “extremely” (4). The Total Mood Disturbance (TMD) score was calculated by summing the scores of the tension, fatigue, depression, anger, and confusion subscales, subtracting the sum of the esteem and vigor subscales, and adding 100. The SWEMWBS questionnaire consists of seven items that measure well-being — responses range from “none of the time” (1) to “all of the time” (5).
Both questionnaires were administered to all participants before the first pool swim, their first sea swim (session 4) and the final sea swim (session 10). The abbreviated POMS also was administered immediately after the sessions listed to measure acute response.
To analyze the data, the authors used SPSS v25 and used analysis of variance (ANOVA) to compare between sessions. Independent sample t-tests and/or Mann Whitney U tests also were used to determine differences between swimmers and controls. Cohen’s D (d) was calculated to measure the size of the effect (small effect = 0.2, moderate effect = 0.6, large effect = 1.2, and very large effect = 2). For the non-normally distributed variables, r was calculated with 0.1 = small effect, 0.3 = moderate effect, and 0.5 = large effect.
Three participants withdrew from the study after the pool swimming session. There were complete data for 49 participants who returned all of the questionnaires at each stage. Overall, there was a 76.5% retention rate for the swimmers and a 91% retention rate for the non-swimming controls. All participants could swim 400 meters in an indoor heated swimming pool and self-verified they were healthy enough to open-water swim. Fifty-nine participants were novice sea swimmers, and two participants had some limited experience swimming at sea.
IMMEDIATE EFFECTS
Significant increases in esteem scores were found following each session (all sessions P < 0.001; (d = 0.6-1.4). Significant decreases in tension, anger, confusion, and TMD also were found following each session (tension and TMD: P < 0.001, d = 0.4-1.1; anger and confusion: P < 0.001, r = 0.4-0.6).
Depression scores also were found to be reduced following the pool and the final sea swims (pool: P = 0.001, d = 0.6; sea: P < 0.001, d = 1.0). Vigor scores also increased following the pool and final sea swim (P = 0.011, d = 0.5 and P < 0.001, d = 0.7, respectively).
In the control group, reduced fatigue following all sessions was found (pool: P = 0.45, d = 0.2; first sea swim P = 0.023, d = 0.2; final sea swim P =.045, d = 0.2. Decreases in tension also were found following the pool session (P = 0.002, d = 0.2) and the first sea swim (P < 0.001, d = 0.9).
DELAYED EFFECTS
The authors also investigated how the participants’ mood and well-being changed between sessions and they referred to this as the chronic response. For both swimmers and controls there was a significant increase in tension scores before the first sea swim compared to the pool session (swimmers: P < .001, d = 0.8; control: P = 0.002, d = 1.0).
Reductions in tension were found in the swimmers before swimming in the pool and final sea swim (P = .025, d = 0.5 and first vs. final sea swim P < 0.001, d = 1.5) and after swimming in the pool and final sea swim (P = 0.009, d = 0.6) and first and final sea swim (P = 0.008, d = 0.6). The controls had significant increases in tension scores between the pool and final sea swim (P = 0.003, d = 0.09 after the swim session P < 0.001, d = 1.1) and between first and final sea swim (P < 0.001, d = 0.07).
After the swim sessions, significant reductions in anger, fatigue, depression, confusion, and TMD were seen in the swimmers between pool and final sea swim sessions (all between P < 0.001 to P = 0.34, d = 0.6-1.1) and between the first and final sea swims (all between P < 0.001 to P = 0.012, d = 0.7-1.0) These findings were not found in the control arm.
Significant associations in well-being were found between the pool swim and the first sea swim (P = 0.004) and between the pool and final sea swim (P < 0.001) among the swimmers, but not the control arm.
The authors also compared the swimmers to the controls and found that the POMS subscale scores were similar between these groups before swims. After all of the swim sessions, the swimmers had higher vigor and esteem scores vs. the control group (all P < 0.001; d = 0.9-1.8 or r = 0.4), and tension, anger, depression, confusion, and TMD scores were significantly lower in swimmers compared to controls (all P < 0.001 to P = 0.023; d = 0.6-3.8 or r = 0.2-0.6).
COMMENTARY
Because this study is a feasibility study and, thus, designed to inform future studies, it is difficult to extrapolate the results to other individuals or populations. However, significant improvements in mood were noted after the individual pool swims and the final sea swims. Overall, the results from this study support that both pool swimming and sea swimming improve mood and that novice sea swimmers may be nervous prior to the first sea swim, as the tension scores suggest. According to the data, as the sea swimmers gained more experience, their tension scores decreased. This study was not designed to evaluate whether sea-swimming is more effective in improving mood than outdoor swimming or the mechanism of action for the changes in mood.
However, there are a number of limitations to this study. Of note, it consisted of two different groups of participating swimmers and controls at different locations, and the authors do not clearly specify how they dealt with these differences with the data analysis. After reviewing the results, it appears that the authors pooled the data from the two different courses and did not discuss the differences between the groups further.
In measuring the acute changes from before the session starts to after the sessions in the POMS tension data on the first day of both pool swimming and sea swimming, both the controls and the swimmers may have been nervous about participating in the study and not the actual swimming.
The authors stated that the first pool swim and the first sea swim were three weeks apart and believed that the delay was reflected in the elevated POMS tension scores of swimmers and controls before the first sea swim. More women volunteered to participate in the study than men, and there was no randomization to the study.
The participants in the study were recruited from the paying customers of the Brighton Swimming School and the Portsmouth Outdoor Swimming group. This may have affected the attrition rate of the participants, since these were customers paying for a course that they were interested in.
From participant comments, the majority wanted to continue sea swimming even after the course had finished. However, there also was no follow-up with the participants to see if they maintained a swimming practice.
The strengths of the study include the use of the validated questionnaires measuring mood and well-being among the participants. Additionally, this study demonstrates that individuals are willing to do pool swims to get comfortable and then learn open-water/sea swimming techniques. There was minimal drop-out of participants during this study, which may be informative when recommending swimming for exercise to individuals who may want to eventually participate in open-water swimming.
Physical activity recommendations include taking at least 150 minutes of moderate-to-vigorous physical activity each week.4 Many individuals do not meet the recommended amount of physical activity per week, and finding a suitable activity that is enjoyable is important.5
For many people, swimming is a suitable low-intensity activity. Open-water/sea swimming may be preferable to many individuals, and this study demonstrates improvements in mood and well-being in both pool-based and open-water swimming. Much more research needs to be conducted to better understand the benefits and risks to open-water/sea swimming vs. pool-based swimming.
The bottom line is that, for individuals who are interested in pool swimming and/or open-water swimming, recommending a swimming exercise regimen to meet physical activity requirements is a good recommendation. There are swimming instructors who teach basic and advanced (including open-water swimming) to students who are interested, and such teachers should be part of a recommendation to inexperienced swimmers.
REFERENCES
- van Tulleken C, Tipton M, Massey H, Harper CM. Open water swimming as a treatment for major depressive disorder. BMJ Case Rep 2018;2018:bcr2018225007.
- Mitchell R. Is physical activity in natural environments better for mental health than physical activity in other environments? Soc Sci Med 2013;91:130-134.
- Huttunen P, Kokko L, Ylijukuri V. Winter swimming improves general well-being. Int J Circumpolar Health 2004;63:140-144.
- Haskell WL, Lee I-M, Pate RR, et al. Physical activity and public health: Updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc 2007;39:1423-1434.
- Guthold R, Stevens GA, Riley LM, Bull FC. Worldwide trends in insufficient physical activity from 2001 to 2016: A pooled analysis of 358 population-based surveys with 1.9 million participants. Lancet Glob Health 2018;6:e1077-e1086. Erratum in: Lancet Glob Health 2019;7:e36.
In a nonrandomized prospective cohort study to demonstrate feasibility, participants showed significant increases in positive mood and well-being as well as a reduction in negative mood states during both pool-based and sea-based swimming lessons.
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