Introduction

Retirement is generally defined as abandoning an occupation and not actively seeking a job [1]. Retirement is a significant turning point in people’s lives as well as important social stress which may affect the physical and mental health [2]. Health-related behaviors may change following retirement and induce changes in the mental health [3]. Physical inactivity is the main cause of death and disease, while physical activity is associated with increased life expectancy as well as decreased risk of developing type II diabetes, coronary heart disease, and some cancers [4, 5]. Meanwhile, physical activity and participation in sports activities play a key role in reducing the symptoms of depression and anxiety as well as enhancing the quality of life and wellbeing [6,7,8,9].

Retirement has been known as a turning point in determining the physical activity behaviors in old age, and indicates a key transition affecting physical and social activities [10]. Physical activity is a modifiable behavior which can change depending on the conditions, events, and major transitions of life [11, 12]. Thus, the pattern of physical activity varies with changes in living conditions, such as the retirement period. The results of studies dealing with changes of physical activity levels after retirement have been contradictory [8, 13,14,15]. Such a contradiction in physical activity levels after retirement can be due to socioeconomic status and previous occupations [16,17,18].

Mental health may be especially sensitive to changes during the retirement period and research in this regard presents different evidence. Some studies have shown that retirement can have a significant relationship with diminished life satisfaction and more psychological distress; however, in other studies no detrimental or positive effect has been reported [2]. Meanwhile, a systematic review study by Barbosa et al. [19] indicated that a number of studies have introduced physical activity as a protective factor for retirement, while Lee and Hung reported that heavy physical activity may be a risk factor [20]. Investigation of the pattern of physical activity as well as its association with mental health and retirement adjustment (RA) has received less attention.

According to van Solinge and Henkens, adjustment is the process of becoming accustomed to retirement-induced changes of life [21]; it is defined depending on how the person assesses their adjustment or adaptation to the retirement conditions as well as its associated changes. While many people enjoy the freedom offered by retirement, approximately 25% experience a decline in adjustment, which leads to adverse psychosocial consequences [22]. The focus of this study was psychological adjustment in retirement, which encompassed criteria of life satisfaction, quality of life, wellbeing, and mental health.

Adjustment to retirement can definitely be the first step towards successful aging [23]. In most developed countries, retirement is often known as a stage of leisure in the person’s life [24]. The change of the role from a routine lifestyle towards a relatively inactive lifestyle is considered a challenge which can trigger development of mental health problems for the retirees [25]. Meanwhile, freedom from the stress of work and having more opportunity for participation in leisure activities may have a positive effect on mental health and adjustment after retirement [26, 27]. Leisure has been found as a protective factor against the changes that occur in the routine life of people; thus, identifying the effect leisure can have on retirees’ adjustment and generally on this stage of life is crucial [28].

Examining previous similar systematic review studies showed that studies on Factors related to adjustment to retirement [19], changes in physical activity and sedentary behavior across the retirement transition according to socioeconomic status [13, 29], determining the status of research evidence about health promotion at retirement [30], the relationship between different types of retirement and changes in health performance [31], the relationship between retirement and depression [32, 33], factors related to well-being in retirement [34], and examining the dimensions of preparation for old age and retirement [35] has been done. As it is known, none of the previous systematic review studies have investigated the relationship between physical activities and leisure with adjustment in retirees. Conducting this systematic review can increase our knowledge of the relationship between the dimensions of physical health and psychological health in retirees. Also, as mentioned above, health-related behaviors may change during retirement; therefore, examining the nature of changes in physical activity and leisure during retirement, in addition to increasing our knowledge, can provide the basis for further research related to this domain.

The growing body of literature about retirement adjustment has rarely dealt with the role of participation in leisure activities during the adjustment process [26]. Assessment of physical activity alongside the leisure activities in retirement adjustment can provide a wider perspective especially about active leisure (such as physical activity and exercises) in comparison to passive leisure (such as reading and watching television). To our knowledge, no systematic review so far has been conducted on the relationship between physical activity, leisure, and psychological adjustment among retirees. Thus, the goals of this systematic review included examining: (1) Whether there is any relationship between physical activity, leisure, and psychological adjustment among retirees? (2) What is the nature of changes in physical activity and leisure activities among retirees? Summarizing and collating the researched results first can elevate levels of evidence beyond our knowledge from single previous studies, and can also be a guide for future research.

Method

A systematic review was conducted to investigate the nature of changes in physical activity and leisure activities, as well as the relationship between physical activity, leisure, and psychological adjustment among retirees. The present study protocol was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [36] and registered in PROSPERO (CRD42022316616).

Search strategy

The search was performed in three electronic databases (PubMed, ISI Web of Science and Scopus) without time or language constraints up to 21 February 2022. A manual search was also performed in the reference list of similar systematic review studies. However, none of the studies were included in the present study in this way because they either did not meet the inclusion criteria or were excluded due to duplication. The keywords used were as follows:

  1. 1

    Concept 1 “Physical Activ*” OR exercise OR sport OR recreation OR “leisure activ*” OR “Physical exercise” OR “motor activ*”

  2. 2

    Concept 2 Adjustment OR well-being OR “Quality of Life” OR “Mental health” OR Life Satisfaction

  3. 3

    Concept 3. Retirement OR retiring OR retire OR retirees OR retired (retir*)

The search was done as extensive in order to ensure sufficient literature coverage. The search strategy was related to retrieving papers that included each of the three above concepts in the “title/abstract” or medical subject headings (MeSH). In the PubMed database, the “title/abstract” or “medical subject headings (MeSH)” strategy, in the Web of Science database, the “Title” and “Abstract” strategies separately, and in the Scopus database, the “Title/Abstract” strategy was used during the search. The precise process of search strategy is available online in the Additional file 1.

Study selection

The screening and selection of papers was done by two authors independently and any disagreement was resolved through consensus with a third reviewer.

The inclusion criteria were as follows:

dddd

  1. 1

    Studies that dealt with assessing physical activity or leisure and psychological adjustment (components described in the PICO: Intervention = physical activity or leisure and Outcome = psychological adjustment).

  2. 2

    The participants included male and female retirees without age restrictions (components described in the PICO: Population: retirees).

  3. 3

    The studies had been performed with an observational design (cross-sectional or longitudinal).

Exclusion criteria included the following:

  1. 1.

    Studies that selected retirees with specific health conditions (such as retirees with an illness or retirees who had recently undergone surgery). These retirees may have different leisure time and physical activity than normal retirees, or they may not be physically active.

  2. 2.

    Studies that only studied the elderly population, did not focus on choosing retirees as a research sample. The conditions of a retired person in terms of physical activity and psychological adjustment may be different from that of an elderly person.

  3. 3.

    Studies that have investigated different aims from the present study goals and have reached different results.

  4. 4.

    Studies that have examined the specific age range before retirement (such as youth, and middle age). The focus of this study is on people after retirement.

  5. 5.

    Papers that’s its full text has been non-English.

  6. 6.

    Experimental studies and studies with these characteristics (literature review, books, review papers, unpublished manuscripts, and conference abstracts)

Quality assessment

To evaluate the methodological quality of cross-sectional studies, Joanna Briggs Institute (JBI) Critical Appraisal Checklist was used, while for longitudinal studies, Newcastle-Ottawa Scale (NOS) was employed. Therefore, the risk of bias was evaluated using two scales, JBI and NOS. The risk of bias in each study was done by two authors independently, and any disagreements between assessors were resolved through consensus with a third reviewer. NOS scale has eight items evaluating four dimensions of sample selection, sample representativeness, comparability, and outcome assessment. Apart from the comparability dimension to which at most two stars are assigned, the other dimensions would be assigned at most one star. More stars indicate higher quality [37].

JBI checklist includes eight items of assessing sample selection criteria, subject description, exposure measurement, subject condition measurement, confounding factors identification, confounding factors control, outcome assessment, and statistical analysis. Each one is classified as yes, no, unclear, or not applicable [38]. For both JBI and NOS designs, the papers with score above 7 would be classified as low risk of bias. The papers with score 5–7 indicate moderate risk of bias, and those with score lower than 5 show high risk of bias.

Data extraction

The main features that were extracted from the reviewed studies included author, year, country, study design, sample size, the age range or mean, gender ratio, exposure variables, outcome variables, measurement tool, main results, and additional results. After extraction, the information was examined by two authors in terms of data accuracy. Due to heterogeneity in applying the measurement tools as well as the results and measurement of the researched variables, it was not possible to perform meta-analysis. Thus, a systematic review was performed.

Results

Overall, 1458 papers were identified from the three databases of PubMed, ISI Web of Science, and Scopus. After removing duplicates and irrelevant cases, as well as abstract analysis resulting from inspecting the title, abstract, and methodology, 119 studies became eligible for investigating the full text. Eventually, 26 papers matched the inclusion criteria and were included in the study. The process of selection of papers has been briefly visualized in PRISMA 2020 flow diagram (Fig. 1).

Fig. 1
figure 1

Diagram flow of outcomes of the review

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Methodological quality

Methodological quality assessments of cross-sectional and longitudinal studies are presented in Tables 1 and 2. For cross-sectional studies, quality assessment scores ranged from 3 (minimum quality) to 8 (highest quality). The quality of longitudinal studies ranged within average (score 5) and good (score 9). From among studies examined in both cross-sectional and longitudinal designs, two studies were classified as high risk of bias [39, 40], three as low risk of bias [41,42,43], and all other studies as moderate risk of bias (Tables 1 and 2). The study by Fry & Ghosh [39] received score 3 and the one by Read et al. [40] was assigned score 4. The study by Fry & Ghosh had not used a standard instrument with suitable reliability and validity. In the study by Read et al., the exclusion and inclusion criteria had not been presented. Further, in both studies, the standard criteria used for measurement of the condition, strategies to address confounding factors, and identification of confounding factors had not been explained clearly.

Table 1 Quality Assessment of Analytical Cross-Sectional Studies Using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist
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Table 2 Quality Assessment of Longitudinal Studies (n = 1) Using the Newcastle-Ottawa Scale (NOS)
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Study characteristics

Table 3 shows the characteristics of the papers included in the systematic review. There was no constraint regarding year of publication for selection of papers. From among the studies examined, nine had been performed before 1999, five between 2000 and 2009, and 12 from 2010 onwards. All studies had been written in English. Also, 21 studies had been performed as cross-sectional and five as longitudinal. Most studies (n = 21) had employed primary data, while 5 had utilized secondary data [8, 26, 42, 44, 45]. Studies had been performed in different countries including Australia (n = 6), USA (n = 4), Israel (n = 2), France, Finland, Taiwan, England, Scotland, Iran, India, Sweden, and Turkey (each country one study), and one study had been done simultaneously in two countries (USA and India), one in two countries of the USA and Israel, and 3 in multiple countries. The continent of Asia and Oceania had the largest contribution in terms of the number of studies conducted (each continent six studies), then 5 studies were conducted in the European continent and 4 studies were conducted in the North American continent. Among the remaining 5 studies, three studies were conducted simultaneously in different countries and continents, and two studies were conducted simultaneously in two continents. Overall, 54,043 retirees had been investigated. The sample size ranged from 32 to 33,241 participants. The participants’ age varied within 50–104 years. Out of all subjects of studies, 53.7% were female and 46.3% were male.

Table 3 Main Characteristics of the Included Studies in the Systematic Review
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The main variables examined in studies

From among the examined papers regarding physical activity dimension, 15 studies had dealt with leisure or participation in leisure, 6 studies physical activity or physical exercise, two studies recreation or participation in recreation, two studies participation in sports, and one study had investigated the profile of health promotion (including physical activity) with regards to the adjustment-associated variables among the retirees. Out of the variables associated with the retirees’ adjustment, 11 studies had dealt with life satisfaction, 5 with wellbeing, 6 with quality of life, 1 with adjustment, and 3 with mental health of retirees in association with physical activity and leisure activities.

Relationship between variables of physical activity and psychological adjustment variables among the retirees

The relationship between physical activity and psychological adjustment variables among the retirees is summarized in Tables 3 and 4. From among all studies, 11 had dealt with examining the retirees’ life satisfaction; in seven studies, the relationship between leisure activity and life satisfaction was positive [23, 24, 41, 43, 46,47,48], while in two studies there was no relationship between these variables [49, 50]. Furthermore, two studies had explored participation in leisure with regards to the retirees’ life satisfaction; in one of the studies, there was no relationship [51], while in another study in American sample, the relationship was positive, but again in Indian retiree’s subjects, no correlation was observed between variables [39].

Table 4 Frequency of physical activity and its relationship with retirement adjustment
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Five studies involved examination of the retirees’ wellbeing; two studies had examined the relationship between leisure activity, two exercise and physical activity, and one participation in sports in association with the retirees’ wellbeing. In exploring the relationship between leisure and wellbeing, one study showed that there was a positive relationship between light exercise and negative affect, as well as between social activity and positive affect [14]. In another study in an Israeli sample, a positive relationship was found, but in the American sample, no relationship was found between leisure and wellbeing [52]. In inspecting the relationship between physical activity and wellbeing, in one study in terms of frequency, there was a positive relationship but regarding intensity, there was a negative relationship between physical activity and wellbeing among the retirees [20]. However, in another study, the relationship between variables was weak and gender associated (weak relationship only in women) [53]. The relationship between participation in physical activity and wellbeing was positive in the study by Walsh et al. [9].

The retirees’ quality of life had been investigated in six studies; in three of them the relationship between exercise, physical activity, and quality of life was positive [8, 15, 44]. Also in two studies, a positive relationship was found between leisure activity and quality of life [40, 45]. Further, in another study a positive relationship was found between participation in physical activity and quality of life of the retirees [42].

From three studies that had dealt with investigating the mental health of retirees, in two studies, there was a negative relationship between physical activity and depression [3, 7]; in another study again a negative relationship was found between leisure and depression of the retirees [26].

Eventually, in a study that had dealt with adjustment of the retirees, there was a positive correlation between leisure activity and adjustment among the retirees [54].

Frequency, intensity, and type of physical activity, leisure, and associated variables among the retirees

Table 4 reports the extent and frequency of physical activity and leisure activities. As seen in Table 4, out of 26 studies, in 12 of them, the extent and frequency of physical activity has not been reported. Five studies indicated that retirees were mostly involved in leisure activities such as home entertainment, reading, watching TV and movies, as well as other audiovisual activities, while being less engaged in physical activity, exercise, and the like [14, 15, 43, 49, 51]. Specifically, a study indicated that in terms of time allocated to participation in leisure, 60% of the time would be spent on passive leisure activities, 25% on active leisure activities, and 15% on social leisure activities [49]. Regarding the frequency of participation, Henning et al. [26] showed that participation in intellectual, social, or physical activities increased after retirement. In the study by Conde-Sala et al. [44], 44.1% of samples participated in physical exercises and 79.6% in individual or social leisure activities. The prevalence of retirees’ participation in sports club attendance in the study by Potocink & Sonnentag [42] was 18.8%. Considering extent, a study showed that the retirees participated in a wide range of leisure activities [46]. With regards to individual or group participation, a study showed that the retirees would spend more time on participation in individual physical activity [7]. Considering intercultural variables, a study revealed that the frequency of different types of leisure activities after retirement increased more in the Israeli sample than in the American sample [52]. Concerning the time allocated, a study found that retirement increased the time allocated to moderate-to-heavy physical exercise by more than 1 h per week [8]. The results of the study by Olds et al. [3] indicated that elevation of the physical activity level in retirees was average; light exercise had increased by 14 min per day and moderate-to-heavy exercise by 4 min per day. Another study indicated that the retirees would exercise 11 h per week on average, around 1 h and 34 min per day [20].

Gender differences in the frequency of physical activity and leisure in retirees

Gender differences between men and women in terms of participation in leisure and physical activities are mentioned in Table 4. Among the studies examined in the present systematic review, 24 study had considered both genders, one study only retired women [48], and one study only retired men [43]. In 13 studies, no finding had been reported on the extent and frequency of physical activity and leisure among men and women. Three studies found no difference between men and women regarding participation in leisure and physical activity [3, 46, 54]. In four studies, men had higher involvement than women in leisure and physical activities [8, 15, 50, 52]. A study indicated that although gender comparison was not possible, women had greater participation in physical activities [53]. Also, in a study, the partaking of women in leisure activities was greater with a very slight difference [24]. Further, in a study examining the men and women differences in three types of leisure activities (active, passive, and social), the results showed that women had more contribution in social leisure, while men had greater attending in passive leisure activities. However, there was no difference in terms of participation in active leisure activities [49]. Finally, in a study, women were more active in stretching exercise, while men were more active in walking [20].

Discussion

This systematic review aimed to investigate the nature of changes in physical activity and leisure activities, as well as the relationship between physical activity, leisure, and psychological adjustment among retirees. The main findings of this systematic review which included 26 studies indicated that there has been a significant and positive correlation between physical activity, leisure, and psychological adjustment among retirees; doing physical activity and enhancing participation in leisure activities were associated with higher adjustment, wellbeing, life satisfaction, quality of life, and mental health. Thus, logically it can be postulated that if people allocated the time for working at pre-retirement to physical activity and participation in active leisure post-retirement, they may experience positive changes in indicators of mental health and psychological adjustment during the retirement period [3]. Having reviewed the studies, we found that physical activity and participation in active leisure played a more important role in psychological adjustment and mental health of retirees compared to passive leisure and doing sedentary activities such as watching TV, reading, and other audiovisual activities.

In a limited number of studies, there was no relationship between the main variables. In the study by Krahe [49] and O’Brien [50], it was found that leisure activities were not significantly associated with life satisfaction. Also, the results of Russell [51] indicated that the frequency of participation in recreational activities had no significant positive relationship with life satisfaction during the retirement period. The notable point was that in all three studies, leisure activities had been measured by life satisfaction. Most probably, other factors than leisure are involved in the retirees’ life satisfaction, causing the different results among studies. Confirming this explanation, the study by Kuykendall et al. [55] showed that factors other than the leisure activity itself, such as satisfaction with the level of leisure activity, may contribute to the adjustment of retirees.

The findings of this systematic review showed that the frequency, intensity, and type of physical activity and leisure time reported in the studies were variable. In many studies, no findings had been reported on the frequency, intensity, and type of physical activity as well as leisure. A number of studies also reported that retirees were mostly involved in passive leisure activities. Specifically, Krahe [49] showed that 60% of the time allocated to leisure in retirees was occupied by passive leisure activities. A few studies have also dealt with the spectrum of participation in different types of activities, group or individual participation, examining the intercultural variables involved in participation and the time spent for physical activity as well as leisure. Therefore, it was difficult to make a general organized assessment of the total physical activity among retirees due to the variability of the results of the studies. Obtaining such variable results among studies can be due to the use of varying instruments, single-case questions, and researcher-made questionnaires for measuring the variables. Hence, further research is required on the use of valid tools for assessment of physical activity which have objective criteria specifically for old age and retirees to better understand the changes in total physical activity.

Considering the intensity of physical activities, it seems that physical activity with low-to-moderate intensity can have a more important role in retirees’ adjustment. The study by Lee and Hung [20] showed that although physical activity can, in terms of frequency, have a positive association with wellbeing among the retirees, a negative correlation was found between physical activity and wellbeing in terms of intensity. Lee and Hung study emphasized low-to-moderate intensity exercise for improving the mental health of the old age and retirees. In this regard, Lahti [56] also indicated that retirement increases the time spent on moderate-intensity activity (such as jogging), while heavy activity (such as walking) decreases. Hence, mental health professionals should encourage retirees to do low-to-moderate intensity activities as well as leisure activities such as walking so that retirees could have better adjustment to the retirement period [57].

Gender differences regarding participation in leisure and physical activity had not been examined in half of the reviewed studies. However, in exploring the other half, several studies indicated that men would, to some extent, participate more than women in physical activity and leisure [8, 15, 50, 52]. Nevertheless, in two studies, women showed greater participation with a very minor difference [24, 53]. This difference was not evident between these two genders in several studies [3, 46, 54]. Regarding gender differences in participation in various leisure activities, a study [49] showed that women participated more in social leisure activities and men in passive leisure activities, while there were no differences in terms of active leisure. It seems that encouraging both retired men and women to do physical activities as well as active and meaningful leisure should be among the top priorities of healthcare policy makers to enhance the retirees’ adjustment and their mental health.

Another notable finding in the present study was that assessment of physical activity or participation in physical exercise has received little attention. Many studies have dealt with evaluating recreational or leisure activities. Nevertheless, such studies can arise from the nature of the retirement period and old age. Retirement increases free time and reduces work-related stress; however, the increased time is not necessarily allocated to health-promoting activities, rather the extra leisure is spent on unhealthy lifestyle [58]. Meanwhile, retirees may get involved less with physical activity and physical exercises due to various factors. Confirming this finding, it has been shown that shortage of financial resources during the retirement period, preference of sedentary activities, negative experience of participation in physical activities during the young ages, and low awareness of the advantages of physical activity have been mentioned as the key obstacles against participation in physical activity for retirees [13].

Also, another interesting point found in this study was that except for five studies that had used a longitudinal approach for measuring leisure and physical activity, all studies had been done as cross-sectional. Performing longitudinal studies is very essential for measuring the long-term effect of physical activity on retirees’ adjustment, so that one could find whether the effect of exercise and physical activity would be maintained for the long time or it is a short-term phenomenon. Of course, demographic variables, socioeconomic factors and other confounding variables should be evaluated for real measurement of variables.

Based on the analysis obtained from this systematic review, the focus of studies before 2010 was more on leisure activities, but after 2010, although studies on physical activity have increased relatively, it is necessary to focus more on physical activity and active leisure time in future studies. In terms of the number of samples, 17 studies have less than 500 people, three studies have 500 to 1000 people, and six studies have chosen more than 1000 people as samples; therefore, it is highly recommended to select a sample with a high number in future studies. In terms of geographical focus, the study in the countries of the African and South American continents is very limited, and it is necessary to increase the concentration of studies according to the current research objectives in these countries.

Also, the results of the analysis in the current systematic review in terms of the investigated variables showed that out of 26 studies, 15 studies were conducted on leisure activities and their relationship with psychological adjustment variables, the focus on physical activity was very low; Therefore, the situation of retirees in terms of physical activity and the amount of time participation in physical exercises should be investigated more broadly to psychological adjustment variables. Among the variables of psychological adjustment, although the life satisfaction of retirees has been investigated more than others, the focus of all studies has been on the relationship between life satisfaction and leisure time and participation in recreation, and conducting studies on the relationship between life satisfaction and physical activity and Participation in sports has been very limited, so it is necessary to conduct more extensive studies in this field. Also, based on the analysis of the findings of the present systematic review studies, the relationship between the quality of life, mental health, and adjustment variables to leisure time and physical activity has been evaluated positively, but the relationship between the well-being variable and leisure time and physical activity is variable. Therefore, it is recommended to carry out further studies for a more comprehensive examination of the relationship between these variables.

Strengths and limitations

Since there have been insufficient data about the effect of adjustment on the retirees’ physical activity, thus no causal relationship can be inferred between physical activity and retirees’ adjustment based on the current literature. Nevertheless, the present systematic review for the first time presents evidence on the relationship between physical activity, leisure, and psychological adjustment among the retirees. In the present systematic review, evidence indicated that retirees mostly participated in passive and sedentary leisure activities. This study sets the basis for retirees’ to place more emphasis on low-to-moderate intensity physical activity for enhancing adjustment.

Conclusion

Eventually, it can be stated that active leisure and physical activities cause enhanced psychological adjustment of retirees. In terms of gender, men had somewhat more participation in leisure and physical activities compared to women. Due to use of various tools and inaccuracies in measuring the studied variables, the frequency and type of physical activity as well as leisure reported in the studies were variable. Therefore, the global organized evaluation of the total physical activity among retirees was difficult. The common challenging issue of reviewed studies in the present systematic review was that most retirees were involved in passive leisure activities, and participation in active leisure and physical activities was relatively low. Thus, emphasis should be placed on low-to-moderate intensity physical activity, which are both risk-free and interesting, in the routine of these people’s lives to improve adjustment and reduce risks of physical damage. Also, future studies can deal with usage of more valid physical activity measurement instruments specially designed for old age and retirement. They can also conduct further longitudinal studies to measure the long-term effects of physical activity on the retirees’ adjustment by controlling the confounding variables. On the other hand, in order to ensure design of interventions for enhancing the retirees’ adjustment, further research should be done on reciprocal relationships between physical activity, leisure, and retirees’ adjustment. Finally, in the selection of samples, a larger number of retirees should be examined, especially in terms of evaluating physical activities and participation in active leisure activities and their relationship with the life satisfaction and well-being of retirees.