Introduction

Currently in the world of professional soccer, many underage players are incorporated each year into the professional team structures, some even moving from their family environment and entering the club’s residences. These migrations are mostly national, but also international, made with the promise of future high salaries and lucrative contracts [1]. Considering the number of annual sports licenses, and the quantity of existing professional players, only a small percentage of these players manage to reach the soccer elite and get a professional contract [2, 3]. As a consequence, many players leave sports clubs when they reach adulthood without having completed basic studies and having grown up far from their families [4].

Given this reality, in recent years, various intervention programs have been proposed in the field of education and sports, with the aim of improving the quality of life of these young players [5,6,7]. Other interventions focused on increasing sports participation and health status levels of young athletes [8], as well as transmitting values considered socially positive [9, 10]. These interventions were based on a positive development perspective, providing young people with the opportunity to accumulate optimal experiences through their participation in organized activities [11, 12]. This participation allows young players to have a healthy, satisfying and productive life, developing social relations and taking part to cultural activities. The positive psychology perspective emerged in the ‘50 s and ‘60 s of the twentieth century, allowing the study and dissemination of research related to the positive aspects of the human being. Its influence has been highly relevant in various scientific fields such as education, public health, neuroscience and organizational sciences [13].

Intervention programs based on optimal development and positive experiences are linked to several widely studied phenomena in positive psychology, both at the collective level such as positive institutions [14], and at an individual level such as positive emotions and the flow experiences [15], or positive personality traits [16]. Focusing on traits, within positive psychology they are considered as positive psychological characteristics that can predict various forms of well-being and performance [17]. These traits are commonly called “character strengths", conceptualized as positive features reflected in thoughts, feelings and behaviours, which differ in people based on moral and cultural values [18]. Like all personality traits, character strengths are expressed along a continuum, where three zones can be identified [19]: underuse (insufficiently expressed strengths in situations that call for them), overuse (overexpressed strengths relative to the situation), and optimal use (appropriate degree of expression for a given situation).

Within sport, there is little evidence regarding the use of intervention programs based on personal strengths by sport psychologist, but enhancing character strengths could become a fundamental part of the strategies that optimize athletes’ performance Brady and Grenville [20]. Athletes should be considered as a unique amalgam of their talents, traits and resources that gives them a competitive advantage in their performance context [21]. According to this perspective, helping athletes to develop their unique and exclusive strengths would allow them, potentially, to develop a solid sports confidence.

Boosting character strengths implies improving other variables that increase psychological adjustment, when individuals are taught to use character strengths within the optimal use zone. Based on results from randomized controlled trials, it has been suggested that character strengths facilitate exceptional performance and predict an increase in well-being, self-regulation and satisfaction with one's own psychological needs for relatedness, competence, and autonomy [22, 23].

Looking at the relationship of character strengths with these variables in greater depth, interventions carried out using character strengths led to improvements in performance satisfaction [24, 25]. Similarly, other studies recently showed how character strengths are tightly related to perceived happiness, well-being, and the absence of ill-being [26, 27]. This relationship found in many cross-sectional studies turns out to be stable over time [27].

Concerning the association between character strengths and self-regulation, research has shown positive relationships between these two variables in cross-sectional and randomized-control designs [28]. Mindfulness training stands out as a promising method to strengthen this relationship, enhancing character strengths over long periods of time [28, 29]. Finally, regarding basic psychological needs, strengths use provides a key support in the attainment of greater need satisfaction. The need satisfaction has a direct influence on motivation, as the perception of satisfying the needs of competence, autonomy and relatedness generates a state of self-determination [30,31,32].

In line with previous interventions with young athletes aimed at promoting their positive optimal development, we have designed an intervention program called “DÉPORVIDA”. This program specifically aims to discover and enhance character strengths in young soccer players, improving their levels of sports performance satisfaction, well-being, self-regulation, and basic psychological needs. In addition, DÉPORVIDA seeks to overcome the existing research-practice gap within the study and intervention on character strengths, where practice moves faster and faster and it is necessary to empirically study the effectiveness of the interventions [33].

The DÉPORVIDA program is based on the values in action (VIA) model, the most widely used one on character strengths [34]. This model identifies 24 strengths, grouped around 6 virtues, as shown in Table 1. Character strengths are seen to be the psychological ingredients defining the virtues [35]. The validity of the VIA model has been confirmed in numerous investigations [18, 36, 37], across 75 nations [38], including the validation work in a cross-cultural sample of 447,573 participants [17].

Table 1 Character strengths of the peterson and seligman model (2004)
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Based on previous scientific evidence, as well as on the activities of the DÉPORVIDA program—which are specifically designed to act on the character strengths described in the VIA model—we hypothesized the program to be effective in promoting the desired improvements. In particular, we expect to observe improvements in terms of sport performance satisfaction, well-being, self-regulation and basic psychological needs.

Methods

Participants

The sample consisted of 28 players belonging to the base soccer categories of the Real Club Deportivo de La Coruña S.A.D, who came from different geographical locations within Spain. Participants were 85% of the players who lived in the club’s official residence. Their age ranged between 14 and 19 years (M = 16.07; SD = 1.63). Their competition level was regional and national, and their experience in soccer practice ranged from 8 to 16 years (M = 11.61, SD = 2.08).

Participation in the program was voluntary and was proposed to all 33 players who lived in the club’s residence. An explanatory video of the program was presented to all players. In this video, they were invited to participate in the DÉPORVIDA program, and to attend a meeting where objectives and activities would be explained. Among all players, 10 agreed to participate to the program, 18 did not agree to participate but accepted to serve as a control group, and the remaining 5 did not participate to the study. All participants involved in the study completed all the assessment phases.

The current Spanish and European regulations regarding data protection were considered at all times. The study followed the recommendations of the Ethics Commission of Research of the University of A Coruña and the Declaration of Helsinki (1964). Informed consent was obtained for each participant; regarding underage players, informed consent was obtained from the parents and the club, considering the overall transfer of rights that they give to the club once the season begins.

Design and measures

A quasi-experimental study was carried out, as shown in Fig. 1, where the intervention group appears in the first row, while the control group appears in the second row.

Fig. 1
figure 1

Quasi-experimental design of the intervention

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The program activities were additional to the normal training schedule of the players, and were carried out in group, for eight consecutive weeks, between February and April 2019. All activities were directed by the club employees with formal academic education (in psychology, pedagogy or sports science); in addition, all of them had a university master’s degree in teaching. In each workshop, the different strengths of the VIA model were trained. Activities were not directly related to soccer, but it was used as the basis for the explanation of various principles. The schedule of the activities, their objectives, as well as their relationship with each character strength and dependent variables, can be found in Appendix. These activities were scheduled during participants’ free time, not to interfere with the normal daily activities of all players living in the club's residence (i.e., school classes, training and competitions). For this reason, some activities were carried out during the weekends. The activities had a variable duration, depending on their characteristics, ranging between 1 and 3 h.

Independent variables

The first independent variable was Intervention, with two levels: (1) intervention with the activities of the DÉPORVIDA program (intervention group); (2) no intervention (control group). The second independent variable was Time, with two levels: (1) initial evaluation; (2) final evaluation.

Dependent variables

The dependent variables measured during the initial and final evaluations were the following ones.

Sport performance satisfaction

The Performance Satisfaction Scale was used [39], which evaluates performance satisfaction at the present time, throughout the season, and assessing the entire sports career. The three items can be used individually, or as a factor, since together they have a Cronbach’s alpha of 0.74. Responses are collected on a 5-point Likert scale: 1 = Very dissatisfied, 2 = Dissatisfied; 3 = Neither satisfied nor dissatisfied; 4 = Satisfied; 5 = Very satisfied.

Well-being

The following scales were used:

  1. a)

    the Fordyce Questionnaire [40], translated into Spanish and available on the University of Pennsylvania website [41]. This questionnaire presents a test–retest reliability coefficient of 0.86. Participants indicate the percentage of time in which he/she is happy, neutral and unhappy, totalled up to 100% between the three. In addition, subjects must evaluate their degree of perceived happiness from 1 to 10.

  2. b)

    the Spanish adaptation of Ryff's Psychological Well-being Questionnaire was used [42], which presents the following factors: self-acceptance, positive relationships, autonomy, control of the environment, personal growth and purpose in life. The values of Cronbach's alpha in these factors are ranging from 0.70 to 0.84. Responses are collected on a 6-point Likert scale ranging from 1 (completely disagree) to 6 (completely agree).

Self-regulation

The factors of Emotional Control and Attention Control of the Spanish Adaptation of the Test of Performance Strategies 3 Competition Subscale were used [43]. These factors are measures of the athletes' capacity for self-regulation (cognitive and emotional) during competition [39]. The first factor had a value of Cronbach’s alpha of 0.85 and the second factor of 0.77. Responses are collected on a 5-point Likert scale: 1 = Almost never, 2 = Rarely; 3 = Sometimes; 4 = Often; 5 = Almost always.

Basic psychological needs

The Spanish adaptation of the Basic Needs Satisfactions in Sport Scale was used [30]. This questionnaire contains the following factors: autonomy-choice, autonomy perceived as internal locus of control, autonomy-will, competence and relatedness. The composite reliability values of these factors ranged from 0.87 to 0.95. Responses are collected on a 7-point Likert scale ranging from 1 (completely disagree) to 7 (completely agree).

Data analyses

All analyses were performed using the IBM SPSS Statistics statistical package, version 25.0. The following data analyses were carried out sequentially: first, the descriptive statistics for all dependent variables were calculated. Next, pre-test values of intervention and control groups were compared by means of one-way ANOVAs. Third, mixed design 2 × 2 ANOVAs were conducted for each independent variable. Finally, as follow-up tests for the dependent variables showing a significant interaction, a set of repeated measures and between groups ANOVAs were conducted. For all analyses, the alpha level was set at 0.05.

Results

The descriptive statistics of the study variables before and after the program implementation, both for the intervention (INT) and control (CON) groups, are reported in Table 2.

Table 2 Descriptive statistics of the dependent variables in the pre-test and post-test
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No significant differences were found in any dependent variable at the beginning of the study (i.e., at pre-test). Thus, the two groups were suitable for a quasi-experimental study [44].

A set of mixed design 2 × 2 ANOVAs showed significant time × intervention interactions for the following indicators: seasonal performance satisfaction [F(1, 26) = 9.191; p = 0.005; ƞp2 = 0.261]; percentage of time experienced as happy [F(1, 26) = 8.945; p = 0.006; ƞp2 = 0.256]; and percentage of time experienced as unhappy [F(1, 26) = 7.682; p = 0.01; ƞp2 = 0.228]. The three significant interactions consistently showed an effect of the intervention in the desired direction (Fig. 2).

Fig. 2
figure 2

Statistically significant interactions. The graphs show the three statistically significant interactions that emerged from the ANOVAs, namely for seasonal performance satisfaction, percentage of time experienced as happy, and percentage of time experienced as unhappy. The error bars show the standard error of the mean

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For the variables showing a significant interaction, within groups pre- vs. post-test comparisons were performed. The results revealed that the intervention group, at the end of the intervention, presented an increase in Seasonal performance satisfaction [F(1, 9) = 7.364; p = 0.024; ƞp2 = 0.45]. Instead, the control group presented a decrease in the Percentage of time experienced as happy [F(1, 17) = 10.842; p = 0.004; ƞp2 = 0.389] and an increase in the Percentage of time experienced as unhappy [F(1, 17) = 9.154; p = 0.008; ƞp2 = 0.35]. No significant differences were found for the other comparisons.

Finally, the post-test results for these three variables were compared between the two groups. The results revealed that the intervention group had lower values in Percentage of time experienced as unhappy, compared to the control group [F(1, 26) = 4.308; p = 0.048; ƞp2 = 0.166]. Conversely, no significant differences were found for the seasonal performance satisfaction and the percentage of time experienced as happy.

Discussion

In the present study, we tested whether an intervention program based on the discovery and development of one’s own character strengths, called DÉPORVIDA, entailed higher levels of sports performance satisfaction, well-being, self-regulation, and satisfaction of basic psychological needs.

The results provided empirical support to this hypothesis for some of these constructs. In particular, different trends emerged for participants of the intervention and control groups between pre- and post-test for seasonal performance satisfaction and percentage of time feeling happy/unhappy, highlighting consistent changes in the desired direction. Specifically, the within group comparisons revealed that the seasonal performance satisfaction increased from pre-test to post-test only in the intervention group; instead, in the control group the time experienced as happy decreased and that experienced as unhappy increased. Moreover, at post-test, the intervention group participants reported less time experienced as unhappy than the control group.

These results are consistent with previous studies. The relationship between interventions based on positive psychology and performance satisfaction has been established in previous research [45, 51]. Regarding the relationship between enhancing character strengths and well-being, in terms of percentage of time perceived as happy/unhappy, our results are consistent with previous studies showing that character strengths discovery is strongly linked to happiness indicators [46, 47], as well as other studies related to well-being in both general population [48] and adolescents [37]. Recent research shows that strengths-based intervention promotes enhancements in various aspects of well-being [49], both hedonic and eudemonic (positive emotions, engagement, positive relationships, meaning and accomplishment). In fact, psychological well-being and strengths are closely linked to athletic performance [20].

Although the positive relationship between character strengths and some of the basic psychological needs, such as autonomy, has been previously reported [50], no significant differences were found in this study. We cannot exclude that the small sample size of the present study prevented similar effects from being observed. The other dependent variable for which there were no significant results was self-regulation, perhaps due to the choice of inappropriate methods for its measurement. Indeed, the activities of the DÉPORVIDA program were carried out to promote general self-regulation, while the selected instrument evaluates this construct more specifically during sports competitions.

The current study is limited due to its quasi-experimental nature, since there was no randomization when assigning the participants to the groups. Therefore, although the program promoted improvements in the players who participated in it, the results cannot be extended to the population as a whole with the same degree of validity that a purely experimental investigation would have. Future lines of research could focus on improving the allocation of participants to groups, increasing the sample size, and replicating this program in other sports. In addition, future versions of the program should better design the training for self-regulation and select more suitable tools to measure its effects, to appropriately evaluate also this variable.

To conclude, the present study shows that there is favourable evidence regarding the validity of the DÉPORVIDA program to promote the development of character strengths. In line with the other similar programs in the field of education and sport, this program fosters positive development in young athletes. Given that its nature is not directly associated with soccer, DÉPORVIDA could be applied and tested also in other sports.