The effects of introducing Tabata interval training and stability exercises to school children as a school-based intervention program

Introduction

According to several studies, school children today have less aerobic capacity and less muscle strength and muscle endurance compared to school children some decades ago [1], [2]. Authors point out that the trend in society is moving toward less daily physical activity, and people living more sedentary lives [2], [3], [4]. In the long run, this might create physical problems since children and adolescents are not using their full physical potential, which could affect their bone mass negatively as well as their general health later in life [5].

A recent study showed that increased physical education classes each week over a 7-year period increased the bone mass in girls and increased leg muscle strength, in both boys and girls [6]. A similar program showed no increased fracture risk in children but rather an increased muscle strength [7]. McKay et al. [8] showed that performing counter movement jumps for 3 min per day during an 8-month period increased the femoral bone mass in children who were 10-years-old. Ekblom et al. [2] found that there is a relationship between low physical activity among teenagers and bad motor skills during childhood.

A physically active lifestyle during childhood might help to decrease the risk of developing chronic diseases later in life, [9] and exercise-deficient children need to be identified early in life and introduced to physical activity to adapt to interventions early in life [10]. Physical activity is also said to help children develop a positive self-image [11]; therefore, it is important to strengthen and support children both physically and mentally to help them have a good self-image and self-confidence. Moreover, physical activity is complex and relates to a variety of factors, such as ethnicity, age, gender, etc., all of which have an influence on how physical activity is perceived [2].

Physical activity and motor skill training are important for both medical reasons and social development in children. However, there is a difference as to how the daily requirement of physical activity is sufficient to develop children’s motor skills. Overweight children tend to perform less physical activity than non-obese children when they take part in the same type of activity, [2] and children’s body mass index (BMI) and physical activity should be taken into consideration when it comes to children’s fitness [12]. Moreover, physical activity is important for weight control and reducing stress levels [2].

Today, there is an abundance of information and good knowledge on physical activity and its positive effects, but to use the knowledge in practice seems to be more difficult. After all, it is important that it be fun to exercise and use the body [2], [13]. For some children, school sports can be the first and perhaps the only contact with physical activity, and these children may be more difficult to include and keep engaged in activities outside of school [2], [13]. Raustorp et al. [13] point out that children and young people’s self-esteem affects physical activity, but when adults/parents are physically active together with the children, they present a physically active lifestyle for the children to adopt [13]. According to Faigenbaum et al. [14], it is also important to create a good training environment where children dare to ask questions and also receive positive feedback, where instructions are given in a manner and in a language that children can understand [14].

In the review by Matos and Winsley [15], strength training, like other physical activity, has measurable health benefits such as increasing bone density and muscle strength. It also gives the child an improved strength even if the muscular volume does not increase as in adults [15]. Strength training in children as well as in adults improves the cardiovascular risk profile, [15] psychosocial well-being, and even academic achievement [16]; furthermore, it may also reduce the risk of sports injuries [15], [17] and is often included in weight loss programs for overweight children in order to improve their metabolism [14]. It is important to develop safe, effective, and fun weight training programs that teach using good techniques, when introducing strength training for children and youths [15]. Alberga et al. [18] proposed 10 feasible lessons concerning physical activity for children and gave practical advice based on their collective clinical trial experience, with support from the literature, which is in line with the idea that the purpose of basic training during childhood and adolescence is to establish a routine, which can establish good habits for later in life and also to develop good motor skills [14], [15]. Faigenbaum et al. [14] and Matos and Winsley [15] also point out that there is no explicit age limit when starting weight training; however, there is a requirement that children be physically and mentally mature to be able to understand the instructions in a training program (which, usually happens around age 7–8) [14], [15]. They also expressed that one should find a balance between different muscle groups and joints. They concluded that no negative effects have been found on growth zones or the cardiovascular system when following a properly composed strength training program. Exercises that use multiple joints are preferred [14], [15].

There are many types of interval training programs with different compositions and time spans, where Tabata interval training is one of them [19]. Tabata interval training is usually carried out with 20 s of exercise, followed by 10 s of rest and is repeated for 4-min, that is, a total of eight intervals [19]. Tabata interval training was originally designed to train the Japanese national team in speed skating [19] but is now also used in modified forms in different kinds of exercises.

The overall objective of this mixed-methods study was to evaluate the feasibility of introducing a 4-min Tabata interval training into a lower secondary school context. A further aim was to evaluate the possible effects on: Coordination, balance, and strength.

Materials and methods

A mixed-method, meaning a combination of qualitative and quantitative approaches, was used in the present study to facilitate the interpretation of the intervention and the results of the teachers’ views on the intervention [20]. For ethical and logistic reasons, the children were cluster randomized to either an intervention group or a control group.

Instruments

Initial measurements and physical tests were performed on all participants, both prior to and after the intervention (the week before the intervention started and the week after the intervention ended) in the school facilities. The physical tests were carried out exactly as the first time, at the same place and with the same test leader; the same instructions were given to all of the participants at both test sessions.

The measurements of height, weight, waist, and buttocks were carried out while the participants were wearing thin clothes but no shoes. The school nurse collected all the demographic data.

Weight: entered in kg with an accuracy of 0.5 kg. The same scale was used on both test occasions. Height: given in centimeters, with an accuracy of 0.5 cm.

Buttock dimensions: measured at the widest part of the hip. The measurement was noted in centimeters, with an accuracy of 0.5 cm. The participants stood with their feet together during the measurements. Waist: measured at the narrowest point between the ribs and the hip, noted in centimeters with an accuracy of 0.5 cm. The participants stood in a relaxed manner with their arms crossed. BMI was calculated using the formula: Weight (kg)/length² (m) [21].

Ball bounce from stool

The participant performed the test standing on an upside down stool 25 cm high, with their feet placed at shoulder width (Figure 1). The number of bounces on the floor using the volleyball, with one or both hands, during 30 s, was noted. If the ball was missed, a new ball was handed to the participant. Each bounce on the floor was counted, except for a possible dropped ball. Time started at the first bounce of the ball. The test has been used for different age groups as a coordination test [22].

Figure 1:

Ball bounce from stool.

360° rotation on stool

The participant did four 360° rotations (by choosing either a right or left rotation) on an upside down stool that was 25 cm high. A 360° rotation was complete when the participant returned to the starting position. The rotations had to be conducted as quickly as possible. A failed rotation resulted in a one-second penalty, and the rotation had to be restarted from the starting position. If the rotation failed more than three times, the test was stopped. Each participant got to try the rotation once before starting the test. The test has been used for different age groups and is used as a balance test for children [22].

Running number

The participant stood in front of a cone. Five cones were placed behind him or her at 3 m distances in a semicircle. The cones in the semicircle were numbered 1–5, but they were not arranged numerically. The participant had to run to a specified number, putting his/her hand on the cone, and then run back to the starting cone to get a new number touted, which happened just before the participant touched the starting cone. The run was performed three times and recorded in seconds (s), which was noted from when the first number was touted until the starting cone was touched after the third lap. Each participant had a trial run before the time was taken, and the numbers on the order of the cones were changed after the test round. The test has been used for different age groups and is used as a coordination test for children [23].

Standing long jump

The participant stood with both feet behind a thin gymnastics mat, with his or her arms hanging freely at the side. The participant was allowed to swing his or her arms when initiating the jump. The take-off and landing had to be on both feet. The distance was measured in half-centimeters, from the toes in the standing position to the heels in the landing position [24].

Push-up and kneeling push-up

The number of push-ups that could be done in 10 s, both regular and kneeling, was performed in a prone position by raising and lowering the body using the arms. The number of correctly performed push-ups and kneeling push-ups was noted [25].

Procedure

The study was conducted over a 6-week period and was done in the form of a modified Tabata interval training [19]. The test leader introduced and explained the intervention exercises for the class teachers and the pupils. The total time of the Tabata interval training was 4 min. These 4 min were allocated as 20 s of exercise and 10 s of rest (2:1 work-rest ratio). In total, eight intervals were carried out during the 4 min and were performed by the pupils in the classroom setting. The teacher in each class chose the time during the day when the intervals were performed every school day, that is, a total of 5 days a week, during the 6-week study period. An interval schedule was created through a combination of exercises involving the whole body, using the big muscle groups in the arms, legs, and torso. The exercises were chosen in accordance with the limited space in the classroom setting. The participants were able to challenge themselves every time since they were trying to improve the number of repetitions performed each time. Before and after the intervention, the physical tests above were done.

Intervention program

Intervals 1 and 5

Prone bridge position (static) (trunk and shoulder stability). In a prone position, participants bent their elbows to 90° and supported their bodies with their forearms and toes, with the neck slightly extended and the eyes looking to the front [26], [27].

Intervals 2 and 6

Supine bridge position (static) (trunk, shoulder, and gluteal strength). In the starting position of the bridge exercise in the supine position, the participants bent their knees at 90° and spread both their arms to about 30°, with both hands on the ground (Figure 2) [26], [27].

Figure 2:

Supine bridge position.

Intervals 3 and 7

Push-ups were performed in a prone position by raising and lowering the body using the arms. The body was kept in the same position during the push-up [25].

Intervals 4 and 8

Bounding jumps, an exercise coordinating the arms and the legs. The right arm and left leg were lifted and altered with the left arm and right leg; these movements continued during the interval. At each leg lift, a jump was added on the stretched leg (Figure 3).

Figure 3:

Bounding jumps.

Teacher interview

After the completion of the intervention and the physical tests, a semi structured interview was conducted with the four teachers [28]. The interviews gave the teachers the opportunity to share their views about the intervention. The time required for the interviews ranged from 15 to 20 min. All interviews were conducted in the school at the end of the school day. The interviews were recorded, and data were transcribed. Some examples from the interview guide are: how did you organize the intervention in the school setting? What is your opinion about the intervention when it comes to the children?

Results

Demographic data relating to the study group and the control group are presented in Table 1. There were no significant differences between the two groups (Table 1).

The number of bounces in the ball bounce test increased for both the intervention and the control group after the 6-week period (F = 6.7, p = 0.012). In the standing long jump test, the intervention group showed an increase, while the control group showed equal results pre- and post-intervention, demonstrated by an interaction effect (F = 6.6, p = 0.013). For the push-up and kneeling push-up test, there was an interaction effect, showing improvements in the intervention group, while the control group displayed similar results pre- and post-intervention (F = 9.2, p = 0.004 and F = 4.8, p = 0.033, for respective variables).

No other tests were significant (Table 2). Furthermore, no significant differences were found between the sexes for any of the tests.

Discussion

The overall objective of this mixed-methods study was to evaluate the feasibility of introducing a 4-min Tabata interval training into a lower secondary school context, to be performed every school day during a 6-week period by pupils 6–9 years of age. A further aim was to evaluate the possible effects on: coordination, balance, and strength. The aim was also to explore the teachers’ experiences in integrating the Tabata interval training during the school day. However, the most important finding was that it is possible to conduct this form of exercise in an ordinary classroom setting, with the classroom teacher coaching his or her pupils to perform weight-bearing exercises. This was important since it has been shown that children today do not perform enough weight bearing exercises and the idea that introducing exercises early in life helps children to get automated movements and a habitus to actually exercise, thus, helping them to build increased muscle strength [30]. Being given the opportunity to make exercise a habit during the childhood years and to achieve motoric skills are of importance [10], [14].

According to Ekblom et al. [1], it has been shown that many children today have less strength and endurance in their arm and trunk muscles; therefore, introducing the Tabata interval training at an early age might help to stop the negative trend when looking at the results in this study. The main findings of this study were that the exercises used in the intervention showed a significant improvement in some of the post-intervention tests (push-ups and kneeling push-ups), which probably depends on the increased strength in the arm and chest of the participants in the intervention group. A significant increase was also seen in the standing long jump, which could be connected to the bounding jump. An increasing number of push-ups indicated an increased trunk and arm strength, and the results might be interpreted to mean that the trunk stability had increased for those participants in the intervention group. This is in accordance with Faigenbaum et al. [14] who pointed out the importance of using exercises that improve trunk strength.

The teachers’ experiences were that the Tabata interval training was easy to integrate into the ordinary classroom setting during the school day and that the intervention seemed to have a positive impact on the pupils with regard to concentration during lessons. The teachers were also convinced that more physical activity is needed in the school, which was confirmed by Hills et al. [31] who concluded that the only way to introduce some children to sports is by participating in physical activity in school. The teachers who participated in the exercises gave the pupils an opportunity to see an adult exercise too, which, according to Raustorp et al. [13], is of importance for children’s interest in physical activity. Also, physical activity has to be fun if children are to continue exercising as adults [13]. The teachers placed emphasis on the need for physical activity during the school day to help the pupils to concentrate during lessons. This is in line with previous studies, [16], [32], [33], where pupils were able to concentrate and finish a given task after being included in an exercise program on a daily basis. Moreover, the exercise protocol was made to accommodate the age of the pupils, thus, not too long, not too boring, and not too complicated, and possible to perform in a classroom setting.

One of the strengths of this study was the possibility to include all the children in this Tabata study due to the positive attitudes of the parents and classroom teachers, which is in line with the findings of Glowacki et al. [34]. Nevertheless, interviewing the children would have been a way to deepen the qualitative findings. The design of the intervention may also be a strength since the same Tabata interval training was repeated daily in the same classroom, which made the pupils feel confident about the exercises, despite their young age, according to the teachers. Also, the interviews with the teachers resulted in a deeper understanding of the results through the use of qualitative analysis, which would not have been the same by only analyzing the test results quantitatively.

The main strength of the present study is the mixed-methods design, including the teacher’s perception of the intervention and also the possibility to perform the study in the classroom setting. The exercise protocol was designed to accommodate the age of the pupils, not too long, not too boring, and not too complicated. Finally, it was possible to perform the exercise program in a classroom setting.

One of the limitations could be the short period of the intervention even though a 6-week period is in line with a previously presented study using the Tabata interval training, to show improvement in physical performance [19]. Furthermore, the young age of the participating pupils could be a limiting factor, for example, the aerobic training factor is shown to be limited in this age group [15]. The exercises used, as a test and as forms of training, might have been different, but the ones chosen were exercises that would fit into the physical classroom setting. Also, it was easy to inform the teachers about the exercises so they could instruct the pupils as well as easy for the pupils to perform. It might be a limiting factor to not have studied the differences between girls and boys in this age group, but there are minimal differences on the group level for this group of children [15]. Another limiting factor is that the number of interviews was quite few, and the time that each interview took was fairly short.

Conclusion

The present study showed that the Tabata interval training and stability exercises offered to school children in a school-based intervention program might be one method to increase children’s physical activity in a classroom setting.

The teachers’ experiences of the study were that it had worked well to integrate the Tabata interval training in a classroom setting. In terms of the study, several positive aspects emerged such as pupils having an increased energy level and development in their movement patterns. However, further and larger studies are needed to evaluate this kind of classroom setting activity.