Subjective Quality of Life of Portuguese Karateka: A Comparative Study with General Population

Abstract

Sports and quality of life have a well-established connection. Karate-Dō is now a global scale sport, although it preserves traditional values and behaviors. The main aim of this study is to compare the difference in subjective quality of life levels between people engaged in Karate-Dō and people who are not. This is an exploratory study where a quantitative methodology was used. A globally accepted instrument was used to measure the subjective quality of life: Personal Wellbeing Index©. A total of 186 questionnaires were administered at a national level (online). Of these, 108 were administered to a sample of the general population (not engaged in martial arts) and 78 were administered to a sample of Karate-Dō athletes or karateka. Although the dimension and distribution of the samples does not allow data generalization, these data clearly show a higher quality of life perception, in all domains, in Karate-Dō athletes. Nonetheless, globally and in all the different domains, the level of perceived quality of life can be considered quite positive in Karate-Dō athletes. This finding suggests that the practice of Karate-Dō may have a strong relationship with a high level of subjective quality of life.

1. Introduction

Quality of life is a much talked about subject in modern societies, not only as part of a healthy and happier lifestyle but also as a measurement unit that leads to different politics and projects towards more mentally healthy societies.

Subjective quality of life is also known as well-being or subjective well-being. In this case we used the definition of subjective well-being (SWB) where this is considered a long-term state with the presence of positive affect and the absence of negative affect along with life satisfaction (Diener & Chan, 2011). Subjective quality of life includes one’s appraisal and evaluation of one’s own life. It includes both reflective cognitive judgements, such as life satisfaction, and emotional responses to ongoing life in terms of positive and pleasant emotions versus unpleasant and negative emotions (Diener et al., 2018). The perception of quality of life is subjective, dependent not only on one’s state of physical and mental health, self-reliance, social relations or environmental factors, but also on their life position, interests, life activity, attitudes and adopted value systems (Kotarska et al., 2019).

Three dimensions of subjective well-being should be considered: Subjective well-being: (1) well-being is subjective, depending on the individual’s perception and personal experience; (2) well-being implies not only the absence of negative factors, but also the presence of positive factors; (3) well-being must be seen as an overall measurement rather than a measurement of a single aspect of life (Diener, 1984). Hence, the evaluation of subjective well-being is a multi-dimensional one, framing different aspects of individual life, such as health, safety, finances and spirituality, for example.

Well-being is a dimension of health, especially mental health. From this perspective, physical activity and sports practice emerges as a fundamental aspect of a healthy lifestyle and has a positive impact on subjective quality of life (Silva et al., 2019). However, studies analyzing the effects of physical activity and sports on an individual’s subjective well-being are rare (Pototczny et al., 2022). Although there is insufficient literature to generalize some results, the existing studies show a positive relationship between SWB and physical activity, especially related to positive and pleasant emotions (Buecker et al., 2020).

Sports can be defined as institutionalized competitive activities which involve vigorous physical effort or using complex physical abilities by individuals whose participation is driven by a combination of personal satisfaction and external rewards (Coakley, 2001).

This positive relation between sports practice and subjective well-being is only true when sports are seen as amateur and driven by passion and motivation (Bento et al., 2024). When the practice of a sport is professional, other factors are involved, such as fear and anxiety directly connected to loss of means of subsistence. This reality of amateurism is the Portuguese Karate-Dō reality, where only a few athletes and coaches gain monetary remuneration, usually practicing on a part-time basis (Rosa, 2017).

Karate-Dō is a Japanese-originating martial art that could be described as a self-defence art with empty hands (no use of weapons), where the arms, legs and body are systematically trained and by which an enemy who performs a surprise attack could be controlled with a demonstration of strength equivalent to the use of real weapons (Nakayama, 2012). In short, it is a physical practice where only the athlete’s body is used, without resorting to weapons, to perform self-defence techniques like kicks and punches, either alone (without opponent) or engaging in a direct combat with an opponent.

In the second half of the 20th century, its practice spread out of Japan, becoming global and being practiced worldwide by millions, while it continued to preserve traditional values and behaviour (Figueiredo, 2006). In Portugal, the first Karate-Dō groups started in the late 1960s and the practice has been growing since then, becoming gradually more institutionalized, both in traditional and sports ways of training (Figueiredo, 2006).

Contrary to popular belief, martial sports are not violent; Karate-Dō primarily offers practitioners discipline, respect, and self-control as a basic assumption for engaging in this sport (Nakayama, 2012). This is directly connected to a philosophical concept behind Karate-Dō practice based on traditional Japanese culture and Zen Buddhism—Budō. According to this philosophical concept, Karate-Dō practice is seen as a way of living based on respect for others, courage, humility and the capacity to overcome difficulties (Cynarski, 2022).

Existing studies where subjective quality of life is measured in martial arts athletes showed a direct and positive correlation between these two aspects. A recent meta-analysis reported that engaging in martial arts engenders positive effects on mental health outcomes and supported them as efficacious sports-based interventions for improving well-being and reducing symptoms associated with internalizing mental health problems, such as anxiety and depression (Shala et al., 2022). These findings are supported by studies (Moore et al., 2020; Monterrosa-Quintero et al., 2022; Ciaccioni et al., 2024) where it was shown that practicing sports, especially martial arts, is a factor that positively reduces levels of distress and translates into better psychological well-being in the test populations.

Considering the two main concepts presented (subjective quality of life and martial arts/Karate-Dō practice) and relating them we find the main objective of this study: to compare the difference in subjective quality of life levels between people engaged in Karate-Dō and people who are not. For that, it is necessary to compare a sample consisting of karateka with a sample of the general population that does not practice Karate-Dō in Portugal, in order to observe if they corroborate, or not, the existing knowledge.

2. Materials and Methods

2.1. Data Collection and Sample

These study data were collected by using a written questionnaire that was administered online using the Google Forms© platform (https://forms.gle/1ReCipqxqcjRARef8, available and accessed until 30 September 2023). The link for the questionnaire was sent to some of the researchers’ contacts who in turn sent it to their contacts and so on, in a nationwide “snowball” sampling approach. This resulted in the comparison of two samples: one of individuals not engaged in martial arts, and other of karateka (Karate-Dō athletes).

The first sample consisted of 108 individuals in Portugal not engaged in martial arts. The inclusion criteria were to be over 18 years of age and not be engaged in martial arts.

The second sample consisted of 78 Karate-Dō athletes in Portugal. The inclusion criteria were to be over 18 years of age; to be active in and have more than 2 years of continued practice of Karate-Dō; to be registered in the national federation (Federação Nacional de Karate—Portugal). It is important to mention that, in 2023, there were 17,867 members in the national federation (Federação Nacional de Karate—Portugal, 2023).

2.2. Ethical Considerations

Prior to the administration of this online questionnaire, the study was presented, and approval was requested from the university ethics commission by official form, which granted authorization for this study. Besides this, the questionnaire presented started with detailed information regarding the objectives of the study, data collection and who is responsible for this process. The participants were also informed that participation was voluntary and completely anonymous and confidential.

2.3. Questionnaire Structure and Measures

The questionnaire was in total composed of 15 questions, which were divided into two sections. The first question was a “yes” or “no” answer about the engagement or not in Karate-Dō. Subsequently, in this first section, five questions accounted for sociodemographic characterization. The questions were about gender, age, education, employment status, and place of residence. The second section was composed of the Personal Wellbeing Index© instrument.

The Personal Wellbeing Index is an instrument developed by the International Wellbeing Group with the main objective of measuring subjective wellbeing (International Wellbeing Group, 2024) It was developed based on ComQol and is a multidimensional scale (different domains of life), assuming that subjective well-being is a complex concept and the result of a variety of factors. This kind of presentation has as main advantages an easier “deconstruction” of the theoretical concept, a more solid scale with more conceptual validity, and that it permits inter-cultural validity (International Wellbeing Group, 2024). This scale is composed of eight required items and one optional item. The eight required items are linked to the following different life domains: standard of living, personal health, life achievements, personal relationships, personal safety, community/connectedness, future security, spirituality/religion. The optional item’s main objective is comparison and connection between work and all required items (International Wellbeing Group, 2024). In this study all nine questions were used. These questions were answered using a Likert-like scale between 0 (“Completely Dissatisfied”) and 10 (“Completely Satisfied”), with the value 5 described as “Neutral”. This distribution of possible answers allows us to assume that results under 5 are negative and results over 5 are positive. This instrument was chosen because it is a globally accepted instrument of subjective quality of life evaluation, it approaches quality of life as a multi-dimensional concept, and it is free to use. In this study the Portuguese version of the instrument was used, being already translated and validated for the Portuguese population (Ribeiro & Cummins, 2008).

2.4. Analysis

First, we examined the characteristics of the population, detailing the dataset obtained from questionnaire results. Then, we tried to establish some connections between these characteristics and the instrument results using appropriate statistical tests for descriptive statistics. Next, the results of the Personal Wellbeing Index©, in both samples, were tested to determine the statistical differences between them, using a non-parametric test between two independent samples (Mann–Whitney U). All of this tested our hypothesis that Karate-Dō athletes (or karateka) have a better subjective well-being level than people who are not engaged in this practice.

This statistical analysis was conducted using IBM SPSS© version 26.

3. Results

The results are presented by sample, so there is always a comparison of the data results between samples. Firstly, the sociodemographic data are presented, comparing gender, age, education, employment status and place of residence. Then, the data related to the Personal Wellbeing Index© are presented, question by question, comparing the results using statistics.

For easier comprehension of the data below, the questions of the Personal Wellbeing Index© are indicated by referring to their associated domain (ex. Q1: “How satisfied are you with your standard of living?” is referred to simply as “Standard of living”).

Non-parametric tests were used because of the type and composition of samples, and for all statistical tests used a p level of significance of p < 0.05 was considered.

3.1. Sociodemographic Data

There were some differences between the participants of two samples, not only in the total number but also in their distribution by characteristics.

The sample of the general population not engaged in martial arts was constituted of a total of 108 individuals, of which 47 (43.5%) were male and 61 (56.5%) were female, mainly between 18–24 years old (27.8%), with a bachelor’s degree (53.7%), employed (68.5%) and from the same region (66.7%) (

Table 1. Sample characteristics.

Characteristic	General Population	Karate-Dō Athletes
Gender
Male	47 (43.5%)	63 (80.8%)
Female	61 (56.5%)	15 (19.2%)
Age
18–24	30 (27.8%)	10 (12.8%)
25–29	17 (15.7%)	12 (15.4%)
30–34	22 (20.4%)	19 (24.4%)
35–39	7 (6.5%)	8 (10.3%)
40–44	8 (7.4%)	9 (11.5%)
45–49	6 (5.6%)	8 (10.3%)
50–54	5 (4.6%)	6 (7.7%)
55–59	3 (2.8%)	4 (5.1%)
60–64	0 (0%)	2 (2.6%)
+65	10 (9.3%)	0 (0%)
Education
Elementary school	8 (7.4%)	0 (0%)
Middle school	6 (5.6%)	2 (2.6%)
High school	23 (21.3%)	35 (44.9%)
Bachelor’s	58 (53.7%)	22 (28.8%)
Master’s	13 (12%)	17 (21.8%)
PhD	0 (0%)	2 (2.6%)
Employment Status
Employed	74 (68.5%)	40 (51.3%)
Self-employed	5 (4.6%)	22 (28.2%)
Unemployed	4 (3.7%)	10 (12.8%)
Student	14 (13%)	6 (7.7%)
Retired	11 (10.2%)	0 (0%)
Place of residence (region)
Castelo Branco	1 (0.9%)	0 (0%)
Coimbra	2 (1.9%)	7 (9%)
Évora	1 (0.9%)	0 (0%)
Faro	1 (0.9%)	0 (0%)
Guarda	2 (1.9%)	0 (0%)
Leiria	11 (10.2%)	8 (10.3%)
Lisboa	16 (14.8%)	16 (20.5%)
Portalegre	1 (0.9%)	0 (0%)
Santarém	72 (66.7%)	45 (57.7%)
Setúbal	1 (0.9%)	2 (2.6%)

).

The sample of Karate-Dō athletes was constituted of 78 individuals, 61 (80.8%) male and 15 (19.2%) female, mainly between 30–34 years old (24.4%), completed high school (44.9%), employed (51.3%) and from the same region (57.7%) (Table 1).

Overall, the general population sample was more uniform in gender (with a slightly higher number of females), younger and with higher levels of education than the Karate-Dō athlete sample.

3.2. Personal Wellbeing Index© Data

The results of the administration of the Personal Wellbeing Index© are presented in the table below in the form of mean scores and standard deviation (sd) (

Table 2. Mean scores of Personal Wellbeing Index© answers.

Question	General Population	Karate-Dō Athletes
Q1—Life as a whole	6.11 (±2.79)	7.42 (±1.48)
Q2—Standard of living entry	5.70 (±2.68)	6.88 (±1.59)
Q3—Personal health	6.06 (±3.00)	7.92 (±1.53)
Q4—Achieving in life	5.83 (±2.86)	7.55 (±1.77)
Q5—Personal relationships	6.31 (±2.96)	7.95 (±1.85)
Q6—Personal safety	6.05 (±2.89)	7.95 (±1.82)
Q7—Community/connectedness	6.08 (±2.74)	7.54 (±1.97)
Q8—Future security	5.35 (±2.83)	7.77 (±1.72)
Q9—Spirituality/Religion	5.86 (±3.13)	6.95 (±2.02)

).

The mean results for each domain of the Personal Wellbeing Index© and the “Life as a whole” control question are clearly higher in the Karate-Dō athlete sample and with less variation, being also more uniform.

Since subjective quality of life is a multidimensional concept, it is important to evaluate the connection between these results and demographic variables such as age, gender and education. In this case, because of similarities of results in place of residence and employment status, these two determinants were excluded from this relationship.

Different types of statistical tests were used due to categorical differences among the variables in study. The next table presents the results for significance of these statistical tests (

Table 3. Statistical test results between demographic variables and Personal Wellbeing Index© results in both samples.

	General Population			Karate-Dō Athletes
	Age	Gender	Education	Age	Gender	Education
	Pearson Correlation (p)	Mann–Whitney Test	Kruskal–Wallis Test	Pearson Correlation (p)	Mann–Whitney Test	Kruskal–Wallis Test
Q1—Life as a whole	0.238 (0.013) 1	0.044 1	0.152	−0.074 (0.552)	0.297	0.347
Q2—Standard of living	0.178 (0.065)	0.008 1	0.435	−0.017 (0.885)	0.388	0.624
Q3—Personal health	0.092 (0.343)	0.063	0.227	−0.234 (0.039) 1	0.565	0.485
Q4—Achieving in life	0.147 (0.129)	0.036 1	0.093	−0.154 (0.178)	0.613	0.580
Q5—Personal relationships	0.200 (0.038) 1	0.090	0.279	−0.090 (0.431)	0.314	0.945
Q6—Personal safety	0.191 (0.048) 1	0.044 1	0.568	−0.141 (0.217)	0.528	0.434
Q7—Community/connectedness	0.227 (0.018) 1	0.217	0.650	−0.045 (0.697)	0.715	0.253
Q8—Future security	0.188 (0.052)	0.008 1	0.199	−0.156 (0.174)	0.005 1	0.309
Q9—Spirituality/Religion	0.170 (0.079)	0.011 1	0.076	−0.059 (0.605)	0.913	0.329

¹ Statistically significant.

).

There were more significant results in the general population sample than in the Karate-Dō athlete sample, particularly regarding age and gender. Education seemed to not be related to the Personal Wellbeing Index© in both samples.

The Mann–Whitney U test was applied to the results of the Personal Wellbeing Index© in order to compare the results from both populations, engaged and not engaged in Karate-Dō, to understand if there is some type of connection between them. The median and interquartile variance (var) is also shown in the next table (

Table 4. Mann–Whitney U test comparing Personal Wellbeing Index© results in both samples.

Question	General Population	Karate-Dō Athletes
	Median (Inter-Quartile Range)	Median (Inter-Quartile Range)	Sig.
Q1—Life as a whole	7 (3)	7 (1)	0.081
Q2—Standard of living entry	7 (3.75)	7 (2)	0.035 1
Q3—Personal health	7 (4)	8 (2)	0.003 1
Q4—Achieving in life	7 (6)	8 (3)	0.002 1
Q5—Personal relationships	7 (5)	8 (2)	0.006 1
Q6—Personal safety	7 (4.75)	8 (2)	0.001 1
Q7—Community/connectedness	7 (3.75)	8 (2)	0.006 1
Q8—Future security	6(5)	8 (2)	0.000 1
Q9—Spirituality/Religion	6 (4.75)	7 (3)	0.154

¹ Statistically significant.

).

As we can observe, these results show that, in almost all domains, the test results are significant, leaving to us to assume that these two samples come from the same global population, with this Karate-Dō engagement being the main difference between them.

4. Discussion

The data collected allow us, besides answering the main objective of the study, to understand if there was a difference in the subjective well-being of Karate-Dō athletes compared to people who are not engaged in Karate-Dō; it also allows us to have some understanding of the general population’s subjective well-being.

Considering the significance level in statistical testing we had to consider an average difference of value of one point (1) to be a strong difference between the results of perceived quality of life evaluation.

Answering the main question directly, in a direct comparison of the results between both samples, we can observe that Karate-Dō athletes showed a higher average evaluation value of both perceived quality of life in both the total and in all the different domains. This difference was over 1 point in both the global evaluation and all the different domains; hence, there is a strong difference between both samples. Considering that both samples are part of the same general population, this relationship is even stronger, because we can more directly relate these average result differences to Karate-Dō practice. Therefore, from these results we can infer that there could be something different in Karate-Dō athletes resulting in a higher evaluation of perceived quality of life.

Karate-Dō can be seen from two different perspectives. First, from a western perspective, it is a sport, where the physical effort is the main activity. Physical activity and sport participation is widely accepted as a form of improving well-being and most studies that relate these two concepts show a positive relationship between them (Marquez et al., 2020). The second perspective, from an eastern perspective, Karate-Dō is a martial art of Japanese origin, so it relates physical activity to many values, principles and ways of behaving related to this origin, like Judō, for example. This philosophical background could be the main reason for these subjective wellbeing levels because the karateka engages in a different lifestyle, with better dietary habits, better social relationships and a more disciplined way of living (Pinto & Matos, 2024). A similar study also showed that there is an association between Karate-Dō training and subjective wellbeing and life satisfaction, which can be explained by the self-control and cognitive reappraisal that derives from this philosophical background and lifestyle (Silva et al., 2019). Practicing martial arts (like Karate-Dō) seems to boost self-confidence and self-esteem, resulting in a better perceived wellbeing; however, quality of life is a multi-factorial concept, and other aspects also need to be considered (Ruggeri et al., 2020).

In this study we cannot conclude that Karate-Dō practice by itself improves perceived quality of life in a categorical way because of the dynamic aspect of quality of life, and the samples are not large enough, but the glimpse provided on this subject follows that tendency.

Looking at the results in subjective wellbeing evaluation of the general population, it is also important to discuss some of them.

In Portugal, some recent studies point to a poor perception of wellbeing and low mental health values (Passos et al., 2020), and life satisfaction is, in fact, the worst in the European Union (EU), according to Organization for Economic Co-operation and Development (OECD) (OECD, 2023). The slightly positive results in this study, especially in the “life as a whole” question, shows an optimistic profile of the participants related to the studies presented.

Quality of life and subjective wellbeing are multi-factorial concepts that influence and are influenced by a variety of dimensions in people’s lives. Observing the data, it is possible to conclude that education seems to not be related to Personal Wellbeing Index© results. A higher degree of education should be reflected in higher levels of perceived wellbeing (Wanberg et al., 2020; Özmen et al., 2021). It is hard to explain why this happened, because a higher education level usually unlocks many resources related to it, like higher knowledge levels, more literacy in a variety of domains, and higher income, aspects that have been directly related to perceived quality of life (Edgerton et al., 2011). This lack of relationship is also visible in the Karate-Dō athletes’ sample, where education level also seems to not be important for perceived quality of life. This could be simply explained by some other (unknown) factors of the population that were not studied here.

Considering age and gender as other characteristics that can influence perceived quality of life, the results are interesting.

In general, the population sample, age and gender seem to be closely related to perceived quality of life, as many significant results in the different domains of the instrument can be observed. Analysing the “life as a whole” question in particular, both these variables have significant results, and this helps to establish this relationship between age and gender and subjective wellbeing, because it is a generic evaluation of perceived wellbeing (without any specific domain). Regarding gender, there is a great deal of inconsistency in the studies performed; in some men seem to have better perceived quality of life than women, so it is more related to social gender roles than gender itself (Batz & Tay, 2018). In this case, the gender results could be connected to age results, which was also significant because the great majority of participants are young adults. The Pearson correlation result being negative shows that younger the person is, the stronger the relationship, so younger people present a better subjective well-being level. The explanation for age results is that the happiness curve is U-shaped, attaining higher values before their thirties and after their seventies, and lower values in between (Blanchflower, 2020). In this sample most cases (almost 65%) were under 34 years old. If we sum the 9.3% of people over 65 years old following the U-curve, we have a greater justification for these results.

In the Karate-Dō athletes’ sample there was almost no significant statistical result of the tests performed that related subjective quality of life to sociodemographic factors. This shows that the perceived quality of life results obtained in this sample are more related to Karate-Dō than to the sociodemographic factors. Based on these results, we could conclude that the higher perceived quality of life levels in all domains showed by Karate-Dō athletes were more connected to this practice than to sociodemographic factors. This could be related to the two dimensions of Karate-Dō practice, either from regular physical activity and social participation, or from the philosophical background that shapes the lifestyle of karateka, which is engaged over some time (in this case, over 2 years of regular practice). However, the data collected did not allow for the determination of which is more important. Hence, it is not known if these results come from sports practice rather than specific Karate-Dō engagement, because sports practice is itself connected to better subjective quality of life (Fuller & Lloyd, 2019). In fact, according to existing studies, active sport participation makes people happier (Rodríguez et al., 2011; Ruseski et al., 2014). In the Portuguese population, there is a lack of studies relating sports to subjective wellbeing, but the existing ones conclude similarly to studies about other populations that people relate happiness and subjective wellbeing to sport engagement (Soukiazis & Ramos, 2015; Pototczny et al., 2022). The same is true for other martial arts athletes, but all existing studies are also limited and exploratory (Keita, 2024). Further research is needed to conclude this question.

Another aspect that is important to discuss in this kind of study is social desirability bias. Social desirability bias could be an issue in this kind of study because we ask participants about their perceptions and feelings. This bias is more intense when the questions are asked in person (Larson, 2019). We did not check in a formal way the potential influence of this social desirability; however, the way the questionnaires were administered—online and not in person, with a guarantee of confidentiality and use of a studied and accepted scale of measurement—reduces the risk of this bias (Larson, 2019). We strongly believe that social desirability did not greatly influence the replies given by the participants because they did not have any direct contact with the interviewers and the theme and type of questions are not particularly subjects of social pressure, such as religion or sexuality.

This study had some obstacles that limited the generalization of results and could bias the results. First, the small and heterogeneous samples, total number of participants, gender and education are quite different in both samples, and this could affect the results obtained, although it is hard to understand in what way. Second, previous or actual engagement in other sports or other martial arts was not asked about in either sample, a fact that could have influenced some results and whose bias degree cannot be measured. Further research is suggested in order to better understand the specific relationship of subjective quality of life and Karate-Dō differentiating it from other sports and martial arts.

5. Conclusions

This study, due to its exploratory nature, the lack of previous studies in the area, and the size and composition differences between samples, does not allow global generalization based on the data recorded and their analysis; nonetheless, it presents some interesting results.

At the beginning of the study, we assumed as the hypothesis that subjective quality of life levels were higher in Karate-Dō athletes and that they have some kind of relationship with this practice. In the end this was confirmed from the data collected. Not only was the average result of evaluation of overall subjective quality of life higher in karateka, but this was also true in all of its domains. This difference is considered strong because the evaluation, in comparison with the general population sample, was over 1 on a scale of 0–10. The comparison between both samples also reinforces this sense that there is something different in Karate-Dō athletes that improves their perception of quality of life, considering that participants come from the same population. However, it is not possible to assume that this difference is specifically related to Karate-Dō practice and not to sport engagement in general.

Looking at the general population results, age and gender seem to have some relationship with subjective well-being evaluation; younger people and women seem to present better levels.

Another interesting result is that education levels do not seem to influence subjective well-being evaluation in each of the samples.

We can conclude (in a limited way) that Karate-Dō practice relates to perceived quality of life level in all domains, improving it.

More research is needed in this area to confirm these results, mainly whether this connection between Karate-Dō practice and subjective quality of life is unique to this practice or shared with other sports or physical activities.