This review included studies that examined the effect of training on mood state within soccer players. The literature search was performed using PubMed, Scopus, Web of Science, and Google Scholar and included articles published until August 10, 2022. The oldest article retrieved was published in 2001. Moreover, we performed manual searches of relevant journals and reference lists obtained from published articles. The following English terms and key words were searched using Boolean operators: “mood state” AND “soccer” combined with the key words “training load,” “training period,” “training exercise” and “performance”(i.e., “mood state” AND “soccer” AND “training load,” “mood state” AND “soccer” AND “training period,” “mood state” AND “soccer” AND “training exercise,” and “mood state” AND “soccer” AND “performance”). The inclusion criteria for these articles were: (1) the original studies were published in English; (2) data concerning training load, training period, exercise training or performance; (3) players included soccer players; and (4) studies examined mood state. The exclusion criteria were: (1) studies that included sports other than soccer; (2) studies that did not include any of the parameters evaluated in this review; and (3) reviews, commentaries, interviews or expert opinions, posters, or book chapters (Figure 1).

Two authors independently extracted and reviewed study data to verify if a given study met the inclusion criteria. Disagreements between the two authors on the inclusion criteria were resolved by a third author with experience in the field.

According to Lane (2001), mood is a set of sensations varying in intensity and duration. Chennaoui et al. (2016) reported that emotional mood contributes to an athletes’ likelihood of success or failure in relation to training. This concept refers to the change in emotional state. Athletes may think of this dichotomously and report being in a good or bad mood characterized by overall positive or negative feelings, respectively (Selmi et al., 2020).

To identify practical assessments, researchers examined various psychological dimensions related to training that require less technology such as mood state questionnaires which have been actively researched in recent years (Saidi et al., 2020; Aydi et al., 2022; Picoli and Bueno, 2022). The profile of mood states (POMS) is a self-report questionnaire comprised of 65 items assessing seven mood states subscales (i.e., tension-anxiety, anger-hostility, confusion-bewilderment, depression-dejection, fatigue-inertia, vigor-activity, and interpersonal relationship; Table 1), with the interpersonal relationship subscale often being eliminated from measurement by researchers. Each item is rated on a 5-point Likert scale from 0 (not at all) to 4 (extremely) in response to questions such as “How are you feeling right now? (Aroian et al., 2007). The six subscales of POMS can be combined into a total mood disturbance (TMD) score by summing the (T) scores for the five negative mood subscales and subtracting the T score for positive mood state and adding a constant of 100 in order to prevent negative numbers.

Terry et al. (2003) published guidelines for the definition of each emotional state assessed by the POMS. According to this work, tension is characterized by sensations such as nervousness, apprehension, worry and anxiety. Anger is characterized by feelings that vary in intensity from annoyance or mild aggravation, fury, and irritation. Confusion described feelings of indecision associated with a decreased ability to control alertness and emotions. Depression is associated with a negative self-concept characterized by themes such as disappointment, deficiency, ineffectiveness, and self-blame. Fatigue is characterized by perception of mental and physical fatigue. Vigor represents the state of well-being, power, excitement, concentration, alertness, vitality, and strong ability to execute physical and mental effort. Finally, interpersonal relationships describe more of a trait than a specific state, but a strong score on this subscale is considered to indicate positive emotional state (Terry et al., 2003). These dimensions can be expressed in terms of state or trait depending on whether the instructions accompanying the form guide the participant to concentrate on their feelings at the moment, throughout the day or week of the assessment, or their usual feelings.

Some researchers have distinguished between high performers and low performers based on their pre-competition mood states (Filaire et al., 2001; Casanova et al., 2016). These studies reported that positive emotional state and successful athletic performance are strongly correlated. Specifically, the players who present lower tension, depression, anger, confusion and fatigue scores and higher vigor scores generally have more competitive success than players with the opposite profile as assessed by the POMS questionnaire. This positive profile has been called the “iceberg” profile (i.e., high vigor score and low scores for depression, tension, fatigue, confusion and anger) (Filaire et al., 2001; Casanova et al., 2016).

During high-intensity training periods characterized by heavy TLs, athletes have usually reported significant mood changes (Filaire et al., 2001; Lovell et al., 2010; Picoli and Bueno, 2022). For example, Filaire et al. (2001) showed that mood disturbance increased progressively with higher TL. It has also been shown that acute fatigue during intense training periods was associated with worse mood state and decreased vigor (Lovell et al., 2010; Saidi et al., 2020). Similarly, Fields et al. (2021) reported higher intensities during soccer preseason were associated with more negative mood scores (i.e., anxiety, anger, depression, confusion, fatigue), while indicators of positive mood states (i.e., vigor) decreased. These results are in line with those reported by Filaire et al. (2001), which showed that mood disturbance increased with the training stimulus. Amstrup et al. (2002) examined the effects of sports season on mood states and found no change in POMS scores during the pre-season period. However, vigor decreased and fatigue and depression increased from the end of pre-season to mid-season. Additionally, Miranda et al. (2013) studied changes in mood across of10 weeks of training in young soccer players. This study showed that as training intensity increased throughout the training period, the mood state became more negative (Miranda et al., 2013). However, Silva et al. (2008) reported that POMS scores were stable after12 weeks of high training intensity, suggesting that athletes’ mood states may be more vulnerable during extended periods of intense training.

The relationship between overtraining and mood state has also been investigated. Schmikli et al. (2011) reported a significant increase in depression and anger subscale scores and total mood disturbance (TMD) with overreaching in soccer players. Lovell et al. (2010) found that mood state shifted from more positive to more negative as the competitive season progressed, likely due to increasing TL and accumulating stress. Similarly, during a period of congested matches (10 games over 6 weeks) soccer players reportedly significantly increased fatigue, tension, anger and a decreased vigor compared to the non-congested period of match play (6 games over 6 weeks). They suggested that mood state disturbance is associated with increased physical and physiological load. Additionally, Botelho et al. (2022) showed significantly increased negative mood scores (i.e., tension, depression, anger, fatigue, confusion, and TMD) after7 weeks of intensive pre-season training in female soccer players, suggesting that training intensity increase may be associated with negative mood changes (Filaire et al., 2001). Results from these studies are consistent with the finding that substantial increases in training intensity may result in a decreased ability to concentrate and feelings of disorder, uncertainty, and mental fatigue (Djaoui et al., 2017). These changes in mood are also associated with poorer recovery state and well-being changes in soccer players (Selmi et al., 2020).

The tapering period, characterized by reduced training intensity, generally appears to have a positive effect on mood state. Beykzade et al. (2011) reported that after the tapering period, TMD, fatigue and depression decreased significantly compared to the beginning of the intense training period. Reducing the training intensity during the tapering period can produce a balance between effort and recovery which leads to mood regulation (Beykzade et al., 2011).

Regarding the study during Ramadan, the study by Baklouti et al. (2017) compared the effects of two small-sided game (SSG) training formats (4 × 4 min and 2 × 8 min) on mood state during Ramadan in male professional soccer players. The results indicated that Ramadan and not training increased subjective feelings of fatigue. Along the same lines, the study by Chtourou et al. (2011) which examined the effects of Ramadan fasting on RPE and mood state. They indicated that RPE and fatigue score were higher during Ramadan in comparison with before Ramadan.

Overall, results from studies using the POMS to assess mood state reveal that extended intense training is associated with more negative mood states, whereas periods of reduced training can be useful in restoring more positive mood state. However, short-term intense training may not negatively impact mood state. A summary of 13 studies examining the effects of both training intensity and periods on mood state variation is presented in Table 2.

Limited research has investigated how acute mood state changes with different training exercises in soccer. Those that have indicate that intense training exercises can change mood state in soccer players (Selmi et al., 2017). In fact, Selmi et al. (2018) assessed mood responses to high-intensity interval training (HIIT) in soccer players, with the POMS questionnaire administered immediately before and within 5 min after training. Results indicated a significant increase in negative mood scores (i.e., anxiety, fatigue, and global mood score) and decrease in vigor score. Selmi et al. (2017) also reported that physical small-sided games (SSGs) induced significant improvements in mood state in professional soccer players. In the same study, both HIIT and SSG sessions induced similar physiological responses; in contrast, HIIT resulted in mood disturbance highlighted by increased tension, fatigue and TMD scores, whereas SSGs provided mood balance. The stability of POMS scores in this study may be due to athletes’ motivation during preferred exercise modalities (i.e., exercises using the ball; Selmi et al., 2017). Similarly, Oliveira et al. (2009) reported that fatigue scores increased following a HIIT session in female soccer players. Broodryk et al. (2017) examined the effect of an anaerobic fatigue test (Yo-Yo Intermittent Recovery) on cortisol levels and mood state in female semi-professional soccer players and found significantly increased cortisol, psychological fatigue and TMD and decreased vigor. Sparkes et al. (2018) found perturbed mood state for up to 24 h after intensive SSG during the competitive period in professional soccer. Exercise motivation is associated with positive mood in soccer players and may be achieved using specific drills such as integrating the ball during physical tasks or the use of verbal encouragement by coaches (Aydi et al., 2022). Specifically, Aydi et al. (2022) showed that technical circuit dribbling drills with verbal coach encouragement improved mood state highlighted by decreased scores on negative mood subscales and increased vigor. Together, these studies suggest that verbal encouragement is an effective method to improve mood or prevent mood disturbances during training.

A summary of 5 studies investigating the relationships between exercise session characteristics and mood state variation is presented in Table 3.

Previous studies have examined the relationship between mood state and performance using the POMS questionnaire (Filaire et al., 2001; Miranda et al., 2013). In fact, mood state in soccer is related to competitive performance in terms of win/draw/lose (Casanova et al., 2016). Studies with professional soccer players have shown that athletic performance can improve positive and decrease negative POMS subscale scores (Robinson and Howe, 1987; Filaire et al., 2001; Miranda et al., 2013). Furthermore, Silva et al. (2008) showed that when professional team presented an “iceberg” profile during the training program, with a fatigue score decrease from beginning to middle season, coinciding with the team’s best performance during the season (50% of wins). However, decreased vigor score at the end compared to the beginning and middle of the season, corresponded with poor performance (33.3% wins; Silva et al., 2008). Similarly, Miranda et al. (2013) reported that the overall POMS score increased significantly in male youth soccer players after 10 weeks of training indicating greater TMD, and that the mood state disturbance was correlated with the team ranking in the championship. Mood state also appears to be related to match outcomes. Casanova et al. (2016) indicated that positive mood state (vigor) score increased after lost matches and anger score decreased after won matches during an official female association football tournament while “Iceberg” profiles were observed during all 5 matches regardless of outcome. Lowther and Lane (2002) indicated that vigor was associated with successful match performance and depression score were associated with poor match performance in a soccer team. Oliveira et al. (2009) examined the influence of match results on mood changes in professional female soccer players. They found more positive mood states among winners and more negative mood states among losers at the end of the matches, suggesting that overall mood state is related to match performance in female soccer players. Moreover, Dejongh et al. (2006) examined the relationship between in-season team performance and mood state in professional female soccer players. They showed that tension, depression, anger, and confusion scores were lower and vigor was higher when the team won indicating that poor performance was related to negative mood state in female players. In addition, Filaire et al. (2001) showed lower vigor scores when the performance of a professional male soccer team was below 50.0% wins. It is likely that competition success can lead to improved psychological states including more satisfaction, pleasure, and reduced anxiety, while the effects of defeat can produce poor well-being (Casanova et al., 2016). Alternatively, more negative mood state may decrease competitive performance.

A summary of 6 studies regarding the relationship between competitive performance and mood state variation is presented in Table 4.

Mood regulation strategies may benefit athletic performance (Hashim et al., 2011). In fact, strong athletic performance among soccer players is associated with high positive mood scores and low negative mood scores (Hashim et al., 2011; Bijukumar, 2021). Indeed, researchers have revealed several mood regulation strategies for soccer players (Selmi et al., 2017; Bijukumar, 2021). For example, Hashim et al. (2011) compared the effects of two different relaxation techniques, known as progressive muscle relaxation and autogenic relaxation on the mood of young soccer players and showed that these relaxation techniques induced equivalent beneficial mood responses and can be used to regulate mood state (Hashim et al., 2011). Akimoto et al. (2003) studied the effect of acupuncture treatment on the mood state in 12 women soccer players during the competition period. The results indicate that acupuncture treatment has a positive effect on mood regulation with improved positive mood and reduced negative mood scores. Other less obvious mood regulation strategies may also be effective, such as choices in training programming. For example, Progressive Muscle Relaxation training (PMR)decreased mood disturbance, anger, tension, and fatigue scores in university students (Bijukumar, 2021) suggesting positive impacts on mood state. This may be a worthwhile strategy to examine among soccer players. Selmi et al. (2017) showed that SSG, a training exercise that soccer players found more enjoyable and motivating, provided better mood state regulation compared to HIIT, a less preferred training strategy, despite similar training intensities. Likewise, previous studies have shown that using motivational training exercises can reduce negative emotions and improve mood in soccer players (Hashim et al., 2011; Aydi et al., 2022). Therefore, implementing relaxation training and selection of preferred training exercises could help to regulate the mood state of athletes (Hashim et al., 2011; Bijukumar, 2021).

A summary of 4 studies examining the relationship between training and mood regulation is presented in Table 5.

Mood state in soccer players is related to time of day and to training time (e.g., morning versus evening training) (Chtourou et al., 2012, 2014; Masmoudi et al., 2016; Irandoust et al., 2019; Hsouna et al., 2021; Masmoudi et al., 2021). In male youth soccer players, depression, RPE scores, Hooper Index, and stress were higher in the afternoon than the morning (Masmoudi et al., 2016). In some studies, training in the morning improved mood state (Masmoudi et al., 2016; Irandoust et al., 2019), whereas Masmoudi et al. (2021) showed that only depression and vigor scores, but not anger, confusion, fatigue, inter-relation, or TMD were significantly worse when training at 17:00 h compared to 08:00 h. Across these studies, exercise/training in the morning boosts physical performance and physiological status including perceived energy levels that may have positive feedback effects and perpetuate improved mood. These studies also indicated that morning activities may also confer improved mental health status and productivity throughout the day. Dietary patterns, especially periods of fasting like Ramadan, may be particularly important for time-of-day studies to consider since fasting could impact mood and performance. Chtourou et al. (2012) observed that professional soccer players felt more fatigued in the evening versus morning during Ramadan. However, among youth soccer athletes, aerobic training during Ramadan had decreased anger, confusion, depression, fatigue, tension, and TMD, and increased vigor scores regardless of whether they trained in the morning or evening (Chtourou et al., 2014).

A summary of 4 studies examining the relationship between time of day and mood in soccer players is presented in Table 6.