*Article* **Effect of Physical Exercise Program Based on Active Breaks on Physical Fitness and Vigilance Performance**

**Francisco Tomás González-Fernández 1,2 , Sixto González-Víllora <sup>3</sup> , Salvador Baena-Morales <sup>4</sup> , Juan Carlos Pastor-Vicedo <sup>3</sup> , Filipe Manuel Clemente 5,6 , Georgian Badicu <sup>7</sup> and Eugenia Murawska-Ciałowicz 8,\***


**Simple Summary:** Our study aimed to analyze the effects of 8 weeks physical training on vigilance performance in high school students. Forty-two healthy students were assigned for convenience and matched into two groups, a Control Group (CG) and an Active-Break Group (ABG). The participants were assessed before the training program using the Alpha-Fitness test battery and Psychomotor Vigilance Task (PVT) to observe their physical fitness and vigilance performance. Compared with the pre-test, significant different were observed in the post-test PVT. Results showed a main effect of ABG responding faster than students in the CG group. This demonstrated that 8 weeks physical training have an effect on vigilance performance and improve the efficiency of vigilance in high school students.

**Abstract:** The scientific literature has shown the beneficial effects of chronic Physical Exercise (PE) on a wide range of tasks that involve high-order functioning. For this reason, the present study aimed to investigate the effects of active breaks on physical fitness and vigilance performance in high school students through eight weeks of physical training. A total of 42 healthy students (age = 16.50 ± 0.59 years; height = 171.08 ± 8.07 cm; weight = 67.10 ± 13.76 kg) from one Andalusian high school (Spain) were assigned for convenience and matched into two groups, a Control Group (CG) and an Active-Break Group (ABG). The ABG performed two active breaks (based on strength and self-loading exercises) during the school day, first at 10:00 a.m. and second at 12:30 p.m. The participants were assessed before and after the training program using the Alpha-Fitness test battery and the Psychomotor Vigilance Task (PVT). Significant differences were observed in the post-training PVT results, compared with the pretraining PVT, showing ABG responding faster than CG. Thus, the presents study demonstrated that eight weeks of physical training affects vigilance performance (compared to CG) and improves the efficiency of vigilance in high school students, contributing to enhancement of quality of education.

**Keywords:** physical activity; executive functions; cognitive performance; youth; physical education

**Citation:** González-Fernández, F.T.; González-Víllora, S.;

Baena-Morales, S.; Pastor-Vicedo, J.C.; Clemente, F.M.; Badicu, G.; Murawska-Ciałowicz, E. Effect of Physical Exercise Program Based on Active Breaks on Physical Fitness and Vigilance Performance. *Biology* **2021**, *10*, 1151. https://doi.org/10.3390/ biology10111151

Academic Editor: Paulo Gentil

Received: 7 September 2021 Accepted: 5 November 2021 Published: 8 November 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

#### **1. Introduction**

In the last decade, there has been a rapidly growing interest in the scientific knowledge that links chronic physical exercise (PE) and cognitive performance [1–5]. A comprehensive review of the scientific literature has shown the beneficial effects of chronic PE on a wide range of tasks involving high-order functioning, such as attention, cognitive control, memory, and perception, among others [6]. The vast majority of the studies in this field have focused on the impact of chronic PE on executive functions [5,7,8], and to a lesser extent, on tasks that involve short-term memory [9,10], attention [11], and language processing [12]. However, current research has shown that regular PE produces different constant changes, such as those at the structural level involving angiogenesis or neurogenesis in different areas of the brain, especially in the hippocampus [13,14]. There is also an increase in blood vessels in the hippocampus, cortex, and cerebellum, which increase the supply of nutrients and energy in these neural areas [15]. It has been widely demonstrated that performing regular exercise at moderate aerobic intensities (40% to 80% of maximum oxygen consumption (VO2máx)) acts positively on cognitive tasks such as processing speed, selective attention, and short-term memory [3,5]. Finally, there is an increase in brain structures due to neuronal plasticity, increased vascularization, and neurogenesis (brain plasticity). The evidence suggests that these adaptations produce a better cognitive response in various tasks, including memory, attention, processing speed, cognitive flexibility, and inhibition.

Vigilance refers to the cognitive (attentional) function that determines the capacity to respond appropriately (quickly and accurately) to relevant stimuli [16]. In the laboratory, vigilance is typically investigated using tasks involving the monotonous presentation of stimuli for a relatively long period of time, requiring participants to detect rare events [17] or to simply respond to unpredictable target onsets [18]. Low levels of vigilance result in slow reaction time (RT), response anticipation, or even failure to detect the target. Consistent findings in sustained attention research show a decline in performance with time-on-task, the so-called vigilance decrement. Researchers have suggested that this performance decrement over time reflects a decrease in attentional resources [19–21]. A cursory look at the literature reveals studies investigating vigilance primarily in the context of various everyday activities [22,23]. However, scientific research on the relationship between regular exercise (based on ABs) and vigilance in the high school setting is lacking. In this respect, ABs have been applied in classrooms using different motor games and including varied coordination abilities, locomotor skills (e.g., running, jumping, or sliding), and stability skills (e.g., balance, bending, or turning). Moreover, the results of previous research obtained after physical interventions have found a positive relationship between physical fitness acquired on intervention and cognitive performance [24–26]. Therefore, we suggest that vigilance could be exponentially affected during the school day, and more specifically, that ABs could contribute positively to the vigilance performance, both immediately after ABs as well as chronically, i.e., with a long-lasting effect caused by the chronic implementation of ABs. This may be significant, especially in the academic context, given the importance of vigilance for maintaining optimal performance during the course of the school day [27].

The scientific literature reported to date points to the positive influence of physical fitness on vigilance [28–30]. A small number of studies carried out have been conducted at early ages (i.e., in children from 3 to 12 years old) and show a positive relationship between the level of physical fitness and vigilance. For example, Pontifex et al.'s [31] study examined the performance of vigilance as a function of time-on-task, using an Eriksen flanker task in two age groups (preadolescents with a low level of physical fitness and preadolescents with a high level of physical fitness). Their results showed an increase in the rate of omission error and the number of sequential omissions as a function of time-on-task in preadolescents with low physical fitness. Another study investigated the time course of behavioral performance and brain functioning in preadolescents with high and low levels of physical fitness [31]. The study found a decrease in performance reflected in the incongruent trials in the low physical fitness group, evidenced by an increase in bilateral

activation of frontal and parietal brain regions. In contrast, participants with high physical fitness showed a decrease in physical activity as a function of time-on-task, although in the initial time block, they showed better activity compared with participants with low physical fitness. Bunce [28] carried out research with young and older adults that attempted to analyze the performance of vigilance according to a degree of complexity of the task and a level of physical fitness. Results indicated a smaller decrease in vigilance in the group of older adults with a high level of physical fitness than in the low-level physical activity group. These results are reflected in tasks with high demands on attention resources, e.g., when information or complexity is high.

In summary, the existing literature confirms the important role that PE and the level of physical fitness [10,32,33] play in cognitive performance in areas involving vigilance. However, research on this is still scarce, and a number of questions still need to be answered. The main purpose of this research was to examine the chronic effects of eight weeks of physical training on cognition, specifically on vigilance performance, in high school students. It should be noted that, based on the evidence found in the literature on regular PE and vigilance, most studies are limited insofar as they show experimental designs between groups and can only look for relationships between vigilance and physical condition indirectly. The central hypothesis of the current study is that an 8-week physical training based on AB would enhance physical fitness and vigilance performance, and in doing so, draw a direct link between cognition and PE.

#### **2. Materials and Methods**

#### *2.1. Study Design*

The study was conducted between January and February of 2020. At the time of these observations, the students had completed three months of training and familiarization with training protocols, tasks, and rating of perceived Exertion (RPE) during Physical Education class. A quasi-experimental pre–post design control group (CG) and an active break group (ABG) were used in the present research. The high school students were selected for convenience, assigned and matched into two groups, an ABG and a CG, based on the class to which they belonged. To investigate the effects of an 8-week AB-based Physical Exercise Program on physical fitness and vigilance performance, those in the CG were asked to maintain their ordinary routines and training practices, while those in the ABG modified their training sessions by introducing ten minutes of AB before 10:00 a.m. and another AB before 12:30 p.m.

### *2.2. Participants*

A total of 42 healthy students from a high school in the region of Andalusia, Spain, participated in this study: 25 girls (age = 16.42 ± 0.50 years; height = 167.66 ± 6.30 cm; weight = 64.13 ± 11.78 kg) and 17 boys (age = 16.62 ± 0.71 years; height = 176.53 ± 7.73 cm; weight = 72.06 ± 15.58 kg) as shown in Table 1. Concerning the sample size, the next equation was used: *Sample Size* = *Z*2 × (*p*) × (1 − *p*)/*C2*, where Z = confidence level (95%); *p* = 0.05 and *C* = margin of error 0.05. Participants were recruited from the city of Granada, which has a population in the range from 100,000 to 1,000,000 inhabitants according to the National Institute of Statistics from the Spanish Government (http://www.ine.es/ accessed on 1 March 2021).

Inclusion criteria for the participants in this study were: (i) reporting normal vision and no history of any neuropsychological impairments that could affect the results of the experiment, (ii) not presenting any injuries during the previous two months, (iii) giving consent, and (iv) participating in 85% of the AB during the study period.


**Table 1.** Participants' characteristics (mean ± SD) in the present study.

Note. CG: Control Group and ABG: Active Break Group. VO2max was estimated with the equation by Legger et al., 1982 [34]: VO2max = 5.857 × velocity (km/h) − 19.45.

In addition, all participants completed a healthy lifestyle questionnaire and the short version of the international physical activity questionnaire (IPAQ-SF) [35]. In the first document, they were asked about current sports habits, addictions, and diseases that could impede the practice of physical exercise, while, in the second, we recorded their level of physical activity (PA).

The participants were informed about the main goals of the investigation and signed informed consent forms. Families were informed that they could revoke the participation agreement at any time. The students were treated according to the American Psychological Association (APA) guidelines, which ensured the anonymity of participants' responses. In addition, the study was conducted following the ethical principles of the 1964 Helsinki declaration for human research and was approved by the Research Ethics Committee of the University of Castilla-La Mancha (Hospital Universitario de Albacete, Record April 2020, and internal project n◦ 2020/05/052).

### *2.3. Procedure*

#### 2.3.1. Preintervention

First, the school management team was informed about the study objectives and ensured that the students' parents or guardians had signed informed consent forms detailing the possible benefits and risks. Subsequently, the study and the plan for the structure of every class day were designed together with the school's teachers and advisors. In order for the students not to miss any classes, we use the ABs to improve performance in the classroom. Every task or a test was monitored by one lead researcher assisted by a physical education teacher responsible for the groups, specially trained for accurate and reliable data recording, especially in Physical Fitness assessment.

In the first session, participants filled out the questionnaires (≈10 min to assess the entire group), had the anthropometry assessment (≈15 min to assess the entire group), and tests from the ALPHA-Fitness test battery in the following order: 4 × 10 m speed-agility (≈10 min to assess the entire group) and standing broad jump (≈15 min to assess the entire group). Participants were given adequate time to fully recover due to the neuromuscular characterization of the different tests applied in this session. In addition, the application order that the students followed during the research was always the same. Therefore, the measures taken ensured the recovery. In the second session, participants performed the 20 m shuttle run test (≈30 min to assess the entire group) see Section 2.4. Finally, in the third session, students performed the PVT to determine their basal level of vigilance.

All measures were recorded at the same time of day, between 10:30 a.m. and 14:30 p.m., in the same space and time with the same humidity conditions (30–40%). The students were familiarized with the use of the subjective rating of perceived exertion scale (RPE) during their physical education classes. In addition, the ABG group was instructed in an 8-week PE program based on ABs in the physical education class for three months. Every task or a test was monitored by one lead researcher assisted by a physical education

teacher responsible for the groups specially trained for accurate and reliable data recording, especially in physical fitness assessment. characteristics (each exercise was designed with an adaptation in difficulty and intensity). We followed the guidelines of the American College of Sports Medicine [36] to ensure the

The students completed eight weeks of training based on functional training. In the case of ABG, they performed two ABs (based on strength and self-loading exercises) during the school day, AB1 at 10:00 a.m. and AB2 at 12:30 p.m. (Figure 1). The training program was supervised by the lead researcher and teachers responsible for the ABG and was designed individually for each participant, considering their individual physical

students were familiarized with the use of the subjective rating of perceived exertion scale (RPE) during their physical education classes. In addition, the ABG group was instructed in an 8-week PE program based on ABs in the physical education class for three months. Every task or a test was monitored by one lead researcher assisted by a physical education teacher responsible for the groups specially trained for accurate and reliable data record-

*Biology* **2021**, *10*, x FOR PEER REVIEW 5 of 16

ing, especially in physical fitness assessment.

#### 2.3.2. Intervention A total of 80 ABs was performed by each participant. Training sessions in both ABs

safety of the participants.

2.3.2. Intervention

The students completed eight weeks of training based on functional training. In the case of ABG, they performed two ABs (based on strength and self-loading exercises) during the school day, AB1 at 10:00 a.m. and AB2 at 12:30 p.m. (Figure 1). The training program was supervised by the lead researcher and teachers responsible for the ABG and was designed individually for each participant, considering their individual physical characteristics (each exercise was designed with an adaptation in difficulty and intensity). We followed the guidelines of the American College of Sports Medicine [36] to ensure the safety of the participants. were divided into three phases: (i) warm-up 2 min (dynamic stretching and joint mobility exercises); (ii) training activity ≈8 min (more information in Figures 2 and 3 ); and (iii) cooldown <sup>2</sup> min (stretching exercises). According to the RPE scale, the average intensity of the sessions was between hard and very hard (16.10 ± 1.12). To control the intensity of the training program, we used a google questionnaire that recorded RPE immediately after each AB. Crucially, the CG were instructed to maintain their classroom routines while the ABG performed the AB. The very light average intensity of sessions (6.29 ± 0.42) was also recorded.

**Figure 1.** Schematic representation of the school day procedure of one session of the experimental group. **Figure 1.** Schematic representation of the school day procedure of one session of the experimental group.

In the training activity, students worked in a circuit. Thus, equipment was distributed around the classroom, and students performed the AB exercises in sequence until finished. The exercises of AB1 (4 sets ×12 sec a recovery time between exercises of 10 sec and between sets of 20 sec) and AB2 (4 sets × 10 sec and a recovery time between exercises of 10 sec and between sets of 20 sec) were the same during the whole intervention. However, the progress of all sessions varied by weeks due to the heterogeneity of the sample and the individuals' varied physical conditions. All students were familiarized with the exercises and the exercise intensity (between hard and very hard). Active Break 1 consisted of the following exercises: Push-ups progresssion*:* (i) per-A total of 80 ABs was performed by each participant. Training sessions in both ABs were divided into three phases: (i) warm-up 2 min (dynamic stretching and jointmobility exercises); (ii) training activity <sup>≈</sup>8 min (more information in Figures <sup>2</sup> and 3); and (iii) cooldown 2 min (stretching exercises). According to the RPE scale, the average intensity of the sessions was between hard and very hard (16.10 ± 1.12). To control the intensity of the training program, we used a google questionnaire that recorded RPE immediately after each AB. Crucially, the CG were instructed to maintain their classroom routines while the ABG performed the AB. The very light average intensity of sessions (6.29 ± 0.42) was also recorded.

formed against a wall, (ii) performed on the knees, and (iii) push-ups complete; Dynamic plank: (i) reach and touch plank; (ii) clock plank, and (iii) side plank (left: 2 × 12 + right: 2 × 12); Unilateral jump: (i) lateral jump (left-right), (ii) box step-up performed in chairs of 46 cm (left-right), and (iii) single-leg squat (left: 2 × 12 + right: 2 × 12); Squats*:* (i) wall squat, (ii) counterbalance air squat, and (iii) bodyweight prisoner squat; Lunges with MB: (i) In the training activity, students worked in a circuit. Thus, equipment was distributed around the classroom, and students performed the AB exercises in sequence until finished. The exercises of AB1 (4 sets ×12 s a recovery time between exercises of 10 s and between sets of 20 s) and AB2 (4 sets × 10 s and a recovery time between exercises of 10 s and between sets of 20 s) were the same during the whole intervention. However, the progress of all sessions varied by weeks due to the heterogeneity of the sample and the individuals' varied physical conditions. All students were familiarized with the exercises and the exercise intensity (between hard and very hard).

Active Break 1 consisted of the following exercises: Push-ups progresssion: (i) performed against a wall, (ii) performed on the knees, and (iii) push-ups complete; Dynamic plank: (i) reach and touch plank; (ii) clock plank, and (iii) side plank (left: 2 × 12 + right: 2 × 12); Unilateral jump: (i) lateral jump (left-right), (ii) box step-up performed in chairs of 46 cm (left-right), and (iii) single-leg squat (left: 2 × 12 + right: 2 × 12); Squats: (i) wall squat, (ii) counterbalance air squat, and (iii) bodyweight prisoner squat; Lunges with MB: (i) stationary lunge (without MB and left-right), (ii) stationary lunge with medicine ball of 4, 6 or 8 kg (left-right), and (iii) lateral lunge with MB (left-right).

**Figure 2.** Description of Active Break 1 for high school students. (Arrows represent the movement direction, and S was used for static and D for dynamic movement). **Figure 2.** Description of Active Break 1 for high school students. (Arrows represent the movement direction, and S was used for static and D for dynamic movement).

**Figure 3.** Description of Active Break 2 on high school students. (Arrows represent the movement direction, and S was used for static and D for dynamic movement). **Figure 3.** Description of Active Break 2 on high school students. (Arrows represent the movement direction, and S was used for static and D for dynamic movement).

Active Break 2 consisted of Unilateral jump: (i) lateral jump (left-right), (ii) Box step-up performed in chairs of 46 cm (left-right), and (iii) single-leg squat (left: 2 × 12 + right: 2 × 12); Shoulder bridge: (i) Bridge stationary, (ii) bridge with single leg static hold (left-Right), and (iii) bridge with marching (left-right). Lunges: (i) side-to-side samurai lunges (Left-right), (ii) Knee thrust lunges (left-right), and (iii) jump switch lunges (left-right); Nordic hamstring curl: (i) band-assisted nordic hamstring curl, (ii) bodyweight and support hands, and (iii) inclined curls positioning; TRX biceps bilateral curl: (i) inclined to 75%, (ii) inclined to 60%, and (iii) inclined to 45%; Balance: (i) balance without movement (left-right), (ii) standing crunch with under-the-leg clap (left-right), and (iii) T-Stand with hinge and side bend (left-right).

See Figures 2 and 3 to see the variations provided to students to adjust the level of difficulty to their ability in order to execute the exercise.

#### 2.3.3. Post-Intervention

After eight weeks, both groups were evaluated at the same time of day as in the preintervention session (between 10:30 a.m. and 14:30 p.m.), in the same space, with the same humidity conditions. Everything was the same as in the preintervention session except t that questionnaires and the ALPHA-Fitness test battery were not completed. Notably, after the termination of the study, students from the CG were also given the opportunity to perform the same program as the experimental group.

### *2.4. Measures*

#### 2.4.1. Anthropometry

Height and body weight were measured before the start of the intervention. A bioelectrical impedance analysis (BIA) device (Tanita BC-730) was used to calculate body weight (kg) to the nearest 0.1 kg. Both measures were assessed by one main researcher (Pre and Post). A stadiometer (Type SECA 225, Hamburg, Germany) was utilized to measure the height (cm) to the nearest 0.1 cm. Participants were asked to remove their shoes and other accessories that could influence the assessment. They also had to be vertical and immobile, with arms extended along the body and looking straight ahead in an upright position. For each parameter, only one measurement was collected.

#### 2.4.2. Physical Fitness Assessment

The level of physical fitness was assessed using the ALPHA-Fitness test battery [37]. We followed the protocol established for this test battery and the guidelines of the ACSM [36] to ensure the safety of the participants. In addition, to ensure successful performance in the ALPHA-Fitness test battery, all the students were informed about the protocol to ensure an adequate data collecting process in both groups.

### 20-m Shuttle Run Test

Cardiorespiratory fitness (CRF) was assessed with the 20 m shuttle run test [34]. Students were required to run between two lines separated by 20 m while keeping pace with audio signals emitted from a USB Player with the test protocol. Students started the test with an initial speed of 8.5 km/h−<sup>1</sup> , which was increased by 0.5 km/h−<sup>1</sup> min−<sup>1</sup> (stage duration = 1 min). We recorded the last one-half stage completed as an indicator of CRF. In addition, VO2max was estimated with the equation VO2max = 5.857 × velocity (km/h) − 19.45.
