Introduction

Regular physical activity is widely recognized for its positive impact on children’s physical health, psychological well-being, and emotional development1. Regular participation in physical activity programs not only improves overall health but also reduces the risk of chronic diseases and provides psychological and emotional benefits2. Childhood is a critical period for the development of lifelong healthy habits3, therefore it is essential to understand how different forms of physical activity influence health outcomes. According to the World Health Organization, children and adolescents should engage in at least 60 min of moderate-to-vigorous physical activity (MVPA) daily, including muscle and bone-strengthening activities at least three times a week4. Previous research has reported that being active in childhood makes individuals more active later adulthood5.

Schools play a pivotal role in promoting physical activity through physical education (PE) classes6. PE not only supports physical and motor development7 by encouraging the adoption of more active behaviors5, but also improves cognitive performance8,9. This is particularly important during childhood, as adequate cognitive development contributes to improved psychosocial and environmental adaptation, better mental health, and a higher quality of life10.

PE has been linked to improved cognitive performance, particularly in selective attention, a central component of attention capacity that is crucial for focusing on relevant stimuli while ignoring distractions11. This ability is essential for effective learning and for achieving success in academic, athletic, and social contexts10,12,13.

However, it remains unclear how different types of PE lessons affect attention capacity. Evidence suggests that structured acute physical activity interventions can enhance children’s cognitive functions, but the effects vary depending on the type of exercise, intensity, and cognitive tasks involved13,14,15,16,17. Chang et al.18 suggested a minimum duration of 11 min of exercise to achieve significant cognitive benefits. Regarding the most effective type of acute exercise for enhancing cognitive functions, several studies on children and adolescents highlight the positive effects of aerobic exercise, while conflicting results have been observed regarding more cognitively demanding activities11,13,17,19. Moreover, children’s cognitive functions are influenced by the time of day due to circadian rhythms20, although the extent of these fluctuations can vary depending on factors such as sleep quality, chronotype (i.e., whether a participant is a morning or evening type), the design of the experiment, and the nature of the cognitive task being performed21,22. These inconsistencies suggest that individual and physiological factors may moderate the cognitive outcomes of exercise23,24. One such factor is cortisol (C), a hormone associated with the body’s stress response, plays a significant role in cognitive processes, including attention regulation and memory25,26. The relationship between C and cognitive performance is complex, as moderate elevations in acute C concentrations in response to stress can enhance cognitive function, while excessive levels may impair it25,26. C response to acute exercise in children is modulated by exercise intensity27,28, duration28, timing28 and type29,30, and individual variability31. Moreover, C levels in children follow a diurnal rhythm, typically peaking approximately 30 min after awakening and gradually declining throughout the day, reaching their lowest levels at bedtime32,33. Thus, the timing of PE lessons may have implications for both C levels and cognitive outcomes. Overall, there is limited and inconclusive evidence regarding changes in C levels following different types of acute exercise conducted in a school setting and their influence on attention capacity in children.

Despite the recognized importance of C for cognitive functions, limited research has examined how different types of PE lessons, combined with their timing, affect C levels and attention capacity in primary school children. Understanding this relationship is crucial for optimizing educational strategies that enhance cognitive performance in children.

In this context, it would be useful to examine whether the time and the type of PE lesson proposed influence the C levels and attention capacity of primary school children during the school day.

Therefore, the aims of the study were to: (i) compare the effect of a curricular PE lesson and a cognitively demanding PE lesson on C levels and attention capacity of primary school children; (ii) evaluate the impact of the time of PE lessons (early morning vs. before lunch vs. after lunch) on attention capacity and C levels; (iii) explore the relationship between variations in C levels and changes in attention capacity, assessing whether such variations differ according to time and type of PE lesson.

Methods

Participants

One hundred and sixteen children from 9 primary school classes (from Grade 3 to Grade 5) aged between 9 and 11 years were involved in the study (55 girls and 61 boys). Specifically, there were 36 Grade 3 children, 25 Grade 4 children and 55 Grade 5 children. Children were eligible if they had no attention-deficit disorders, academic and learning difficulties, dyslexia, developmental and neurological disorders, or medical conditions that would affect study results or limit physical activity. This information was obtained through a review of official school records, accessed with parental consent.

Five outliers were identified through a preliminary analysis of C levels at pre-intervention and were subsequently removed from the dataset. Therefore, the final sample consisted of 111 children (52 girls and 59 boys). A demographic description of the sample was reported in Table 1.

Table 1 Demographic description of the sample.
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The University “Niccolò Cusano” Ethical Committee approved this investigation (Unicusano MO 6/22). The study followed the principles of the Declaration of Helsinki. Informed written consent was obtained from both parents prior to study participation.

Experimental procedure

All children participated in two experimental sessions corresponding to the two different types of PE lesson (curricular PE lesson and cognitively demanding PE lesson). Children’s assessment of attention capacity and salivary sample collection occurred immediately before (PRE) and immediately after (POST) both PE lessons. The sequential order of these lessons for each class was counterbalanced and randomized according to a predetermined plan to control the potential learning effects due to test repetition.

Experimental sessions occurred at the same time of the same school day for 2 weeks. The school day was planned to have the same schedule every day during the experimental intervention.

Curricular PE lesson and cognitively demanding PE lesson

Both types of PE lessons had the same structure, total duration (60 min), and intensity, but differed in the cognitive challenges and level of children’s cognitive engagement required during the physical activities. Each PE lesson was structured into three parts: a 15-minute warm-up, a 30-minute main activity phase, and a 15-minute cool-down.

The warm-up phase consisted of aerobic movements such as running in a circle or along a marked line at a slow pace, gradually increasing speed. These activities were accompanied by a musical track or hand clapping and included directional changes, skipping steps, hopping with feet together, fast sprints, forward and lateral kicks, and, finally, deep breathing while walking.

The main activity phase of the curricular PE lesson involved station-based exercises. Children repeated, for approximately 15 min, a circuit consisting of a forward roll, five obstacle jumps over approximately 20 m, a slalom between six cones, multiple jumps inside circles, and, after catching a ball, a quick sprint of about 8–10 m toward the finish line while holding the ball. This continuous aerobic circuit training was followed by a 15-minute shuttle run game. This lesson was focused on improving cardiovascular endurance through the performance of various basic motor patterns previously learned and familiar to the children.

The main activity phase of the cognitively engaging PE lesson involved the sport-unspecific use of basketballs in the context of mini games. This lesson aimed to enhance both motor control and perceptual-motor adaptation skills. It was focused on psychomotor competence and on the expertise in movement-based problem solving with functional use the basketball, considering various tasks that involved manipulative ball handling skills and decision-making motor tasks. Activities were performed in pairs, with one child following the other while engaging in tasks such as dribbling, running, jumping, or passing under their partner. Exercises also included ball passing, maintaining balance on one foot while a partner dribbled, and structured sequences where children, positioned in parallel lines, passed the ball while running, jumping, or dribbling. Directional changes and shooting the ball into a basket were also incorporated. Thus, temporal production, temporal estimations, accurate timing, and spatial adjustments were essential parts of the cognitive requirements to perform such kinds of activities17,34. Additionally, the ball was used in an unconventional and unusual manner, detached from traditional team sports, to encourage inclusive participation and reduce the influence of gender stereotypes in physical activity.

The cool-down phase involved stretching exercises and activities designed following the primary school teaching guidelines, which emphasize physiological development, motor pattern refinement, character building, social and civic skills, and exposure to various sports practices.

During both PE lessons, exercise intensity was monitored using a heart rate (HR) monitor with the aim of delivering two types of lessons at the same intensity level. Specifically, heart rate was recorded using an HR monitor (S610i; Polar Electro Oy, Kempele, Finland) to ensure exercise intensity stayed within the MVPA range (HR > 139 bpm)35. To maintain consistent HR levels, preset target zones corresponding to the MVPA range were established before each lesson. An alarm sounded if a child’s HR fell below the MVPA threshold, helping to maintain continuous exercise intensity and minimize differences between lessons.

Lesson time

The PE lessons took place according to the schedule established for each participating class. Each lesson lasted one hour, with the first lesson starting at 8:30 a.m. and finishing at 9:30 a.m., and the last lesson beginning at 3:30 p.m. and concluding at 4:30 p.m.

Lesson time was defined in three time slots as follows: the first time slot (8:30–9:30); the second time slot, including all lessons held before lunch (9:30 − 10:30, 10:30 − 11:30, and 12:30 − 13:30); and the third time slot, corresponding to the after-lunch lessons (13:30 − 14:30, 14:30 − 15:30, and 15:30 − 16:30).

Evaluation of the attention capacity

The d2 Test was used to evaluate children’s attention capacity36. It consisted of a paper and pencil test in a pre-printed sheet containing 14 lines in each of 47 randomly mixed characters, using only the letters “d” or “p”. Children were asked to mark only the letters “d” between two dashes, having 20 s available for each line. The dashes can be positioned both above, both below, one above and one below the letter. Every 20 s, an acoustic signal invited children to continue the next line. The test had a total duration of 4.67 min. Children were instructed to work as quickly as possible without making mistakes36 (pp. 9–10).

The d2 Test determines the ability to focus attention on a single stimulus/symbol avoiding the distractors. For a correct execution of the test, the involvement of selective attention processes is necessary, as the letter “d” is not only orthographically similar to the letter “p” but there are also many distracting “d” letters with more than two hyphens. Studies emphasized that the result of this test reflects attention capacity and is not correlated with the subject’s IQ19,36.

The evaluation of the d2 Test consisted of the identification of omission errors, in particular, the number of missing characters that should have been crossed out, and the identification of the errors made or rather the number of incorrect letters crossed out. Therefore, the variables measured were the total number of items processed, the percentage of errors and the concentration performance.

The total number of items processed refers to all letters that were processed, both correct ones and those marked incorrectly. It is the quantitative variable of cognitive performance. The percentage of errors evaluates the qualitative aspect of the performance and represents the proportion of errors made within the area of all letters processed. The lower the error rate, the greater the subject’s accuracy. The concentration performance is assessed from the difference between the number of correctly crossed-out letters and the number of errors made, providing a check on response bias. Two familiarization tests were carried out before the test session.

The attentional test was administered in groups (one class at a time) in a quiet environment to minimize distractions. All children were supervised throughout the administration.

Collection of salivary samples

Saliva samples were collected from all the children immediately before and after the two types of PE lessons to assess their immediate hormonal response to physical activity, which may influence cognitive outcomes. Cotton swabs and saliva collection tubes (SALIVETTE, Sarstedt, Germany) were used. Cotton Salivettes demonstrated moderate reliability (r= 0.79)37; and moderate analytical validity (recovery rate: 88.7%)38, for salivary cortisol measurements. All the saliva samples were centrifuged and stored at − 40 °C until analyzed for C.

Statistical analysis

A priori power analysis to determine sample size was completed using G*Power 3.1.9.2 software39. The Type I alpha (error level) at 5% and a Type II beta (error level) of 5% (or a power of 95%) were set a priori. This analysis showed that for the medium effect size of 0.25 and an error probability of 0.05 and a power of 0.95, the sample size would need to be N = 90. Thus, the target size of the sample recruited for this study was greater than 90 students. A sample of this size will provide the study with the requisite power needed to provide valid results40.

Preliminary analysis

A preliminary analysis (repeated-measures ANOVA) was conducted to analyze the differences at baseline in C levels and attentional variables before each lesson (curricular PE lesson vs. cognitively demanding PE lesson) considering lesson time as between factors. Effect size was also calculated using Cohen’s definition of small, medium and large effect size (as partial ƞ2 = 0.01, 0.06, 0.14).

Outliers were identified using the interquartile range (IQR) method. C values at pre-intervention in both conditions (curricular PE lesson and cognitively demanding PE lesson) falling below Q1–1.5×IQR or above Q3 + 1.5×IQR were excluded from the analysis (Q1 corresponding to the 25th percentile, Q3 corresponding to the 75th percentile).

Evaluation of the effects of different types and time of PE lessons on attention capacity and C level

Mean scores and standard deviations were calculated for attentional variables (total number of items processed, percentage of errors, concentration performance) and salivary C concentration. For each measured variable, we calculated the variation (Δ) after each type of lesson with respect to its initial value (POST - PRE).

Repeated-measures ANOVA was used to analyze the change (Δ) in the scores for total number of items processed, percentage of errors, concentration performance, and C levels, based on participation in one of the two types of lesson (curricular PE lesson vs. cognitively demanding PE lesson), considering lesson time as between factors. Effect size was also calculated using Cohen’s definition of small, medium and large effect size (as partial ƞ2 = 0.01, 0.06, 0.14). Significant interactions were further analyzed by means of appropriate post hoc analysis.

Association between the variation in attentional variables and C concentration

Regardless of the lesson type, Pearson’s correlation analysis was used to explore the relationships between changes (Δ) in salivary C levels, in attentional variables and lesson time.

Moreover, Pearson’s correlation analysis was conducted separately for each PE lesson to explore the relationships between changes (Δ) in attentional variables, in ΔC and lesson time.

Evaluation of differences in exercise intensity between the two types of PE lesson

The mean scores and standard deviations of the heart rate during curricular and cognitively demanding PE lessons were also calculated. Significant differences between curricular and cognitively demanding PE lessons intensity were verified using a paired t-test.

The level of significance was set at p < 0.05 for all analyses. Statistical analysis was performed with SPSS Version 27.0 statistic software package.

Results

Preliminary analysis

The preliminary repeated-measures ANOVA was conducted to assess potential baseline differences in C level and attentional variables, considering both types of lesson and the three defined time slots. No significant baseline differences were observed in C level between the two types of lesson. However, a significant difference was found in C levels at baseline when considering lesson timing (F2108 = 34.79, p < 0.001, ƞ2 = 0.392). Specifically, C levels were significantly different between the first time slot, that is higher compared to the second and the third time slot, respectively (Fig. 1a), suggesting a potential influence of the time of day on this variable. ANOVA revealed a significant main effect of lesson type on the total number of items processed (F1108 = 32.72, p < 0.001, ƞ2 = 0.233) and concentration performance (F1108 = 23.33, p < 0.001, ƞ2 = 0.178). These results revealed that the total number of items processed and concentration performance were higher in cognitively engaging PE lesson than in curricular PE lesson (Table 2). No significant baseline differences were observed in attentional variables among the three time slots.

Fig. 1
figure 1

C levels (a) and ΔC (b) in the three time slots. *p < 0.05 vs. the first time slot.

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Table 2 Means and standard deviations of attentional variable scores and salivary C concentration (nmol/L) for both curricular and cognitively demanding PE lessons.
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Moreover, 5 outliers were identified and removed from the analysis.

Evaluation of the effects of different types and time of PE lessons on attention capacity and C level

Repeated-measures ANOVA was conducted to examine changes (Δ) in total number of items processed, percentage of errors, concentration performance, and C levels, considering lesson type (curricular PE lesson vs. cognitively demanding PE lesson), lesson time (first time slot vs. second time slot vs. third time slot), and the interaction between lesson type and lesson time (lesson type × lesson time). The results of the analysis are presented in Table 3.

Table 3 ANOVA results of the change (Δ) of attentional variable scores and salivary C concentration.
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The significant main effect of lesson type revealed that cognitively demanding PE lesson led to a lower improvement of the total number of items processed and concentration performance than the curricular PE lesson (Table 2).

The significant main effect of lesson time revealed that Δ total number of items processed was significantly higher in the first time slot compared to the third time slot (p < 0.05) (Fig. 2a). Similarly, Δ concentration performance was significantly greater in the first time slot compared to the third time slot (p < 0.05) (Fig. 2b), suggesting that attention capacity was higher in the early morning sessions than in the later afternoon sessions.

Fig. 2
figure 2

Δ Total number of items processed (a) and Δ Concentration performance (b) in the three time slots. *p < 0.05 vs. the first time slot.

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Finally, a significant difference in ΔC was observed between the first time slot and both the second and the third time slots (Fig. 1b), reinforcing the influence of lesson timing on this variable.

No significant differences were found for Δ percentage of errors (Table 2).

Association between the variation in attentional variables and C concentration

Regardless of the lesson type, the correlation analysis revealed no significant relationships between ΔC and Δ total number of items processed, Δ percentage of errors, Δ concentration performance (all p > 0.05). Lesson time showed significant correlations with some of these variables. Specifically, lesson time was negatively correlated with Δ total number of items processed (r = − 0.170, p < 0.05) and Δ concentration performance (r = − 0.165, p < 0.05), suggesting that the time of day influenced attentional variables. Specifically, PE lessons later in the day were associated with smaller changes in both the total number of items processed and concentration performance. Additionally, lesson time was positively correlated with ΔC (r = 0.253, p = 0.000), indicating a potential relationship between lesson timing and C variation.

Specifically, PE lessons earlier in the day were associated with greater changes in C level. No other significant associations were observed (all p > 0.05), suggesting that these factors operate independently of the PE intervention. In addition, the relationship between changes in attentional variables, changes in salivary C levels and lesson time was examined separately for each PE lesson. The results of these correlation analyses are presented in Table 4.

Table 4 Correlation coefficients (r) between change (Δ) in attentional variable scores, in salivary C concentration (nmol/L) and lesson time for both curricular and cognitively demanding PE lessons.
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The correlation analysis revealed significant relationships between ΔC and lesson time, as well as between lesson time and other attentional variables (Δ total number of items processed and Δ concentration performance), in both types of lesson (r = 0.265 and r = 0.241; p < 0.05). These results emphasize that there is a lesson time effect for ΔC and attentional variables (Δ total number of items processed and Δ concentration performance) in both types of lesson. Specifically, both types of PE lessons later in the day were associated with smaller changes in the total number of items processed and concentration performance. Moreover, both types of PE lessons earlier in the day were associated with greater changes in C level. No significant correlation was found between ΔC and changes in attentional variables for both curricular and cognitively demanding PE lessons (all p > 0.05).

Evaluation of differences in exercise intensity between the two types of PE lesson

The heart rate verified that both types of PE lessons (curricular PE lesson vs. cognitively demanding PE lesson) had similar exercise intensity (146.5 ± 14.0 vs. 147.2 ± 15.5 bpm, respectively; p > 0.05).

Discussion

The first two aims of the present study was to examine and compare the effect of a curricular PE lesson and a cognitively demanding PE lesson on attention capacity and C levels of primary school children according to timing of PE lessons.

The significant main effect of lesson type revealed that the curricular PE lesson led to a greater improvement in both the total number of items processed and concentration performance compared to the cognitively demanding PE lesson. This result suggests that, while both types of PE lessons benefit attentional performance, the curricular PE lesson is more effective in enhancing attention and concentration. Given that exercise intensity was the same in both lessons, this effect may be attributed to the differing characteristics of the two lesson types. Previously, Budde et al.19 showed that 10 min of acute bilateral coordination exercises were more effective in improving performance on concentration and attention tasks compared to a normal sports lesson of the same duration in healthy adolescents. The authors hypothesized that the coordinative nature and the cognitive challenge of the exercise could lead to pre-activation of the cerebellum and frontal cortex, which are also responsible for mediating functions such as attention. Similarly, Anzeneder et al.23 found that 15 min of high-challenge exergames led to better performance on the Attention Network Task compared to lower-challenge exergames. The authors hypothesized that both physical exertion and cognitive engagement are arousing and thus enhance children’s attentional resources.

However, in our study, it seems possible that the combined demands of the cognitively demanding PE lesson, resulting from both physical and cognitive effort, may have caused excessive stress or load, leading to a reduced improvement in attentional performance. This is consistent with our earlier findings13, which showed that a cognitively challenging intervention lasting 50 min led to children’s smaller cognitive improvements compared to physical activity without cognitive engagement. Similarly, Egger et al.41 demonstrated that an acute bout of cognitively engaging physical activity may actually impair children’s cognitive performance. These inconsistent findings could be attributed to differences in the duration of cognitively demanding physical activities, ranging from 10 min19 to 50 min13. Moreover, Egger et al.41 speculated that younger children may benefit more from exercises with lower cognitive complexity, whereas older children might gain greater advantages from more cognitively challenging activities, suggesting that the cognitive demands of physical activity should be appropriate to children’s individual characteristics.

Another key finding of this study is that ΔC did not differ significantly between the two types of PE lessons, as both were associated with a reduction in C levels by the end of the lesson. This suggests that, at the same exercise intensity, both PE lessons could effectively reduce C concentration. We could cautiously hypothesize that PE lessons serve as a pleasant distraction from regular academic instruction, potentially contributing to a reduction in overall school-related stress. Similarly, Becker et al.42 found a C decrease in children during outdoor lessons, probably due to the ‘green effect’ that generated positive effects on psychological well-being by inducing a physiological reduction in C.

Moreover, results of our study showed that the PE lesson time significantly influenced both attention capacity and C levels. Specifically, the most substantial improvements in attention capacity (Δ total number of items processed and Δ concentration performance) were observed during the first time slot, while the least improvement occurred during the third time slot. Similarly, C reduction was most pronounced in the early morning, with smaller reductions observed later in the day.

These results may be explained by the influence of circadian rhythms on C secretion and cognitive performance, as attention, a key cognitive function, exhibits time-dependent fluctuations20,22. A study conducted by Oueslati et al.20 reported significant variations in children’s cognitive performance across different times of the day. Specifically, children’s attention and mental flexibility were significantly higher in the early morning than later in the day. Contrarily, Valdez22 emphasized that all components of attention fluctuate throughout the day, with the lowest levels in the early morning (07:00–10:00) due to the influence of sleep inertia, followed by an improvement from 10:00 to 14:00, and then an after-lunch dip between 14:00 and 16:00. Our finding of enhanced attention capacity in the early morning aligns with the results reported by Oueslati et al.20 and partially agrees with those reported by Valdez22. The decline we observed in the after-lunch time slot corresponds to the after-lunch dip identified by Valdez, further supporting the influence of circadian rhythms on cognitive performance. These inconsistent findings may be attributed to differences in research methodologies, types of attention assessed, sleep quality, participant chronotypes (morning vs. evening types), and differences in experimental design.

Moreover, our study revealed a significant effect of PE lesson timing on C levels, demonstrating the dominant influence of the circadian rhythm on C release. The ΔC during the first time slot was greater than that observed in both the second and third time slots.

Similar to our study, Kanaley et al.43 conducted a study to determine the influence of the time of day on C response to acute exercise in young men. They found higher levels of C in the morning, consistent with the circadian rhythm, during which C naturally peaks shortly after waking. However, unlike our results, which showed a more pronounced reduction in C after the morning PE session, possibly due to the pleasant effects of structured PE, Kanaley et al.43 found that morning exercise elicited a greater C response compared to later sessions. These discrepancies may be attributed to differences in exercise intensity or to the age of the populations studied (children vs. adults). However, the greater cortisol response during morning exercise in children and adults can be explained by the natural post-awakening cortisol peak, which provides an already high hormonal baseline onto which physical activity adds further stimulation44.

A study that investigated the effects of gymnastics sessions conducted in the morning (at 09:00) and in the afternoon (at 14:00) found no significant differences in C levels between the two time points in children aged 6 to 11 years45. Further research is needed to investigate time-of-day-related C responses to physical activity in children.

Supporting the influence of lesson timing on C levels and attentional performance, the correlation analysis revealed significant associations between ΔC and lesson timing, as well as between lesson timing and the attentional variables.

Indeed, the third aim of the present study was to explore the relationship between variations in C levels and attention capacity, assessing whether such variations differ according to time and type of PE lesson.

No significant correlations were found between changes in C levels and changes in attentional variables in both types of PE lesson. This suggests that the reduction in C is not directly responsible for the cognitive improvements observed. This result is consistent with findings from other studies that did not observe an influence of C on cognitive function27,46. Budde et al.27 reported a lack of significant correlation between C levels and working memory performance in school-age children. The authors hypothesized that this absence of correlation could be due to the moderate exercise intensity, which may not have been sufficient to induce a significant increase in C concentration. Supporting this, Ponce et al.46 found that neither moderate nor vigorous exercise intensities affected working memory performance in male college students, despite eliciting different levels of sympathoadrenal activation (i.e., heart rate increase) and increases in salivary C. Similarly, in our study, exercise intensity was monitored and maintained at a MVPA intensity during both PE lessons. Therefore, we suppose that the pleasant nature of the PE lessons may have contributed to the observed attentional improvements, independently of changes in C. This supports the idea that positive experiences during PE can enhance cognitive performance, possibly through neurobiological mechanisms unrelated to C.

Moreover, cognitive performance encompasses a wide range of skills, including memory, attention, executive functions, and problem-solving skills. Different cognitive tasks can be affected differently by stress and C levels26,47. In our study, we investigated the effect of PE on a specific executive function, attention. Therefore, the lack of a significant correlation between C levels and cognitive performance could also be attributed to the fact that only one executive function was measured, which may not have been sufficiently sensitive to detect a relationship between cortisol and cognitive functioning.

Strengths and limitations

One of the limitations of the present study is that it focused only on attention capacity. Future research should examine other cognitive domains, including memory and executive functions, to better understand the relationship between C and cognitive performance. We distinguished between two types of PE lessons: curricular PE lesson and cognitively engaging PE lesson. However, the activities in the curricular PE lesson were predominantly individual, whereas those in the cognitively engaging PE lesson were primarily conducted in pairs. This difference may have influenced children’s engagement and enjoyment during the activities. Nevertheless, we did not assess children’s perceived enjoyment, pleasure, feelings, or level of distraction, all of which could affect cortisol responses and attentional outcomes. Including affective and motivational measures in future research would provide a more comprehensive understanding of the relationship between physical activity, C response, and cognition. Another limitation of the present study is the absence of a control group. Future research including a no-activity control group is necessary to strengthen the research methods of the study.

A strength of the study was the evaluation of qualitative rather than quantitative characteristics of physical activity in the modulation of C levels and cognitive functioning in primary school children.

Conclusions

This study demonstrates that a curricular PE lesson is more effective than a cognitively engaging PE lesson in enhancing attention capacity of primary school children. C variation after both PE lessons was influenced by the lesson time. The attentional improvements observed were influenced by both the timing and the type of PE lesson, but they were not directly related to changes in C levels. These findings suggest that scheduling PE lessons in the early morning maximizes cognitive benefits and stress reduction. Furthermore, the study highlights the importance of considering both cognitive demands and circadian rhythms when designing school curricula to optimize cognitive and emotional outcomes.