Effects of Tabata Training During Physical Education Classes on Body Composition, Aerobic Capacity, and Anaerobic Performance of Under-, Normal- and Overweight Adolescents

Physical education classes often fail to include su cient exercise intensity to induce changes in body tissue composition and physical tness. Short-term high-intensity interval training protocols incorporated into physical education lessons are one possible solution to this problem. Existing studies have not examined how individuals di ering in body mass index (e.g., normal-weight, underweight) respond to high-intensity interval training exercises. Therefore, this study aimed to evaluate the e ects of a Tabata protocol on body composition measurements, aerobic capacity, and motor performance in underweight and overweight adolescents (the experimental groups) vs normal-weight adolescents (here regarded as the control group). The sample included 58 adolescents (28 boys, mean age=16.2 years; 30 girls, mean age=16.2 years) who completed the high-intensity interval training and the following set of measurements pre- and post- intervention: height, weight, body fat percentage and waist-to-hip ratio, physical e ciency index (based on the Harvard Step Test), agility (in 4 10 shuttle run test), and lower-limb muscle power in vertical jump. The results showed that high-intensity interval training was e ective in reducing body weight, waist-to-hip ratio, and body fat percentage only in overweight individuals. Improvement in aerobic capacity was found only in underweight and overweight boys. Further research should focus on the development of customized exercise protocols and their adaptation to girls and assess the sustainability of the changes induced. Keywords:high-intensity interval training; body mass index; health-related tness; students 1. Introduction

reducing body weight, waist-to-hip ratio, and body fat percentage only in overweight individuals. Improvement in aerobic capacity was found only in underweight and overweight boys. Further research should focus on the development of customized exercise protocols and their adaptation to girls and assess the sustainability of the changes induced. Keywords:high-intensity interval training; body mass index; health-related tness; students 1. Introduction Malnutrition in all its forms, including overweight, obesity, and underweight forms, is the primary cause of global health deterioration. Currently, over-nutrition and undernutrition (especially in third world countries) are widespread across the globe and a ect individuals in every country and region of the world [1]. Both malnutrition problems (over- and underweight) are a ecting healthcare costs. Scienti c evidence suggests that the global trend of a steadily increasing percentage of both overweight and underweight individuals is increasingly a ecting children and young people [2,3]. Overweight, obesity, and underweight forms in childhood and adolescence may bring about numerous consequences and lead to health problems in adulthood. Being underweight increases the risk of infectious diseases. In girls, it often causes menstrual cycle disorders and increases the risk of Int. J. Environ. Res. Public Health2020,17, 876; doi:10.3390 /ijerph17030876 /journal/ijerph

Int. J. Environ. Res. Public Health2020,17, 876 2 of 11 miscarriage, preterm birth, and faster involution of the reproductive system in adulthood [4–6]. Being overweight or obese in childhood often persists in adulthood [7] and leads to numerous diseases of a uence, such as type-2 diabetes, cardiovascular diseases, and metabolic diseases, and, consequently, leads to premature death [8–11]. Body weight is linearly related to body mass index (BMI). For this reason, BMI is an essential biological measure of a population's biological condition and related social phenomena [12]. Due to its strong relationship with physiological markers, BMI is a predictor of diseases of a uence. The categorization of BMI allows for the identi cation of subsets of the population prone to di erent health complications. Many researchers have focused on nding optimal methods to combat obesity and overweight. Results have shown that one of the most important and e ective methods to address obesity and overweight is physical activity [13,14]. Actions taken to address the problem of malnutrition include the development of programs for the promotion of physical activity and their implementation in physical education (PE) in schools. PE classes are considered an ideal setting to promote healthy physical activity and prevent overweight and obesity [15], helping to ensure that physical activity becomes more frequent among all students. However, studies on the bene ts of such programs are inconclusive. Di erent degrees of e ectiveness have been shown depending on the type of exercise, the form of the classes, and the range of parameters analyzed. The most common e ects are those related to the reduction of BMI and body fat and, sometimes, improvement in physical tness in obese and overweight individuals [16]. However, no studies have examined underweight individuals, for whom a reduction in body weight or body fat would be undesirable. Physical tness tests should be introduced into health monitoring systems—Ortega et al. [17], especially those testing the e ciency of the cardio-respiratory system, the base for physical e ciency, and muscular tness and speed-agility, the base for motor performance [18]. It also remains unclear what type of program,

whom a reduction in body weight or body fat would be undesirable. Physical tness tests should be introduced into health monitoring systems—Ortega et al. [17], especially those testing the e ciency of the cardio-respiratory system, the base for physical e ciency, and muscular tness and speed-agility, the base for motor performance [18]. It also remains unclear what type of program, type of exercise, duration, and volume constitute optimal training for inducing the desired changes in adolescents. The results of a few studies have indicated that high-intensity interval training (HIIT) may be appropriate. The training is based on a short intervention time (up to several minutes) of very intensive e ort (from 75% HRmax). Such intensity in this training improves the maximum oxygen uptake in adolescents [19]. The e ects of this protocol have been presented by numerous authors [19–23]; however, such analyses were carried out in groups of young people without consideration of the variation in their BMIs. Determination of the impact and e ect size of HIIT in children and adolescents with di erent BMIs should be a basic objective of research based on the principle of individualization, including the division of young people into not only normal-weight, overweight, and obese but also underweight groups. Furthermore, the e ectiveness of programs conducted in natural conditions (i.e., during PE lessons at school) also needs to be veri ed. In searching for novelty in the area of studies on HIIT programs in PE, we determined that there appear to be no studies in which participants were separated into underweight, normal-weight, and overweight groups. Therefore, this study aimed to evaluate the e ects of a HIIT program based on the Tabata procedure on body composition, aerobic capacity, and motor performance in underweight, normal-weight, and overweight adolescents (divided by gender). The working hypothesis of the present study was that the HIIT intervention would a ect body composition, aerobic capacity, and motor performance independently of BMI status. Di erent gender results are expected also. 2. Methods 2.1. Participants Participants comprised boys and girls aged 16 years (see details below) from a Polish general secondary

normal-weight, and overweight adolescents (divided by gender). The working hypothesis of the present study was that the HIIT intervention would a ect body composition, aerobic capacity, and motor performance independently of BMI status. Di erent gender results are expected also. 2. Methods 2.1. Participants Participants comprised boys and girls aged 16 years (see details below) from a Polish general secondary school. The students who attended the school were of the same sociocultural level and lived in the same geographical area (i.e., a big city with about 650,000 inhabitants). In addition, they were

Int. J. Environ. Res. Public Health2020,17, 876 3 of 11 recruited on the basis of two inclusion criteria. The rst criterion required being in the rst year of general secondary school (10th grade), during which the HIIT program was introduced. The second criterion was that parental consent had to be obtained to participate in this research. Exclusion criterions were metabolic diseases or asthma. It was implicated of medical contraindications. High-intensity interval training (HIIT) is generally a form of interval training alternating short periods of intense anaerobic exercise with less intense recovery periods, until the participant is too exhausted to continue. The students followed a 14-min HIIT exercise regimen based on the Tabata training method, presented in the form of a video during one of three PE lessons per week. Tabata training takes its name from Izumi Tabata, who examined changes in the aerobic and anaerobic systems after high intensive interval training (HIIT) utilizing his own protocol. The Tabata protocol was followed for a period of one school semester (10 weeks). The remaining PE lessons were conducted in accordance with the PE curriculum adopted by the school for rst-year students. The diets of the participants were not analyzed, but students were instructed to maintain their diet and normal level of activities of daily living and not to engage in any other organized physical activity outside of the PE classes [24]. Participants comprised 39 boys and 45 girls who attended the Tabata program. The analysis was based on data from 28 boys (mean age=16.2 years, SD=0.4) and 30 girls (mean age=16.2, SD=0.4) who completed the HIIT program as well as a set of measurements before and after the intervention and who were not excluded on the basis of the aforementioned inclusion criteria. Data were excluded from participants involved in organized physical exercise (i.e., a tness gym) or additional recreational activities during the previous six months (three girls, four boys), those who had medical contraindications for motor activity and/or cardiovascular and respiratory diseases (three girls, one boys), those who discontinued participation in PE classes (as a result of school or group/class change; ve

Data were excluded from participants involved in organized physical exercise (i.e., a tness gym) or additional recreational activities during the previous six months (three girls, four boys), those who had medical contraindications for motor activity and/or cardiovascular and respiratory diseases (three girls, one boys), those who discontinued participation in PE classes (as a result of school or group/class change; ve girls, four boys), and those who failed to complete all tests ( ve girls, two boy). No participants withdrew from the program due to fatigue or lack of interest. The included participants were divided into three groups: underweight (BMI<18.5 kg/m 2 ), normal-weight (BMI=18.5–24.99 kg/m 2 ), and overweight (BMI 25 kg/m 2 ). Underweight and overweight adolescents were regarded as experimental groups and were compared with normal-weight adolescents, who were regarded as the control group. The study was approved by the Ethics Committee of the University of the Physical Education in Wroclaw (ECUPE No. 33/2018). The study was also conducted in accordance with the ethical principles for medical research involving human subjects contained in the Declaration of Helsinki by the World Medical Association. Additionally, the study met the “ethical standards in sport and exercise science research” [25]. All participants and their parents were asked to provide written informed consent prior to the study. 2.2. Procedures Morphological and motor measurements were performed before and after the 10-week intervention. The tests were conducted on one day, from 8:00 a.m. to 1:00 p.m., in sports halls in standard conditions for each group. Each participant was wearing a T-shirt, shorts, and shoes. Only anthropometric measurements were conducted without shoes. The measurements were performed in the following order: anthropometric measurements, vertical jump, 4 10 m shuttle run agility, and the Harvard Step Test. The protocol used for each measurement was based on recommendations for the assessment of health- and skill-related physical tness [26]. 2.3. Anthropometric Measurements Morphological measurements included body height, with an accuracy of 0.1 cm, using anthropometers (GPM Anthropological Instruments, DKSH Ltd, Switzerland) and body weight and body fat percentage (BF%) using an InBody230 body composition analyzer (InBody Co. Ltd, Cerritos, CA,

protocol used for each measurement was based on recommendations for the assessment of health- and skill-related physical tness [26]. 2.3. Anthropometric Measurements Morphological measurements included body height, with an accuracy of 0.1 cm, using anthropometers (GPM Anthropological Instruments, DKSH Ltd, Switzerland) and body weight and body fat percentage (BF%) using an InBody230 body composition analyzer (InBody Co. Ltd, Cerritos, CA, USA) with the bioelectrical impedance method. The tool has very high reliability.

Int. J. Environ. Res. Public Health2020,17, 876 4 of 11 InBody230 was reliable in men and women as indicated by high intraclass correlation coe cients for BF% ( 0.98), FM ( 0.98), and FFM ( 0.99) and low standard error of measurement [27]. Before the measurement, participants were asked to excrete, refrain from drinking excessive amounts of water and not change typical breakfast patterns. BMI was calculated based on body height and weight. Furthermore, waist-to-hip ratio (WHR) was calculating. 2.4. Aerobic Capacity (Harvard Step Test) Aerobic capacity was assessed using the Harvard Step Test. Physical e ciency index (PEI) was next calculated. Reliability of this test is acceptable at the intraclass correlations coe cient (ICC)=0.63 [28]. The Harvard Step Test is very useful because it requires minimal equipment, no calibration, and is possible to be conducted indoor. From the school class point of view, it takes only 8 minutes (5 minutes of exercise, 3 minutes of monitored recovery) to complete, in addition, several people can be measured simultaneously. The participants stepped up and down at a constant pace on a stool with a height of 41.3 cm. The process began with the participants stepping onto and o of the step box at a pace of 30 cycles per minute with a metronome set at 120 beats per minute (bpm). The exercise was performed for a period of 300 s, less if the participants were compelled to stop owing to fatigue. The recovery pulse was recorded as the bpm during the 1 min after completing the test. Prior to each test, heart rate monitors (Polar H1, Polar Electro; Kempele, Finland) were tted to each schoolchildren's chest, level with xiphoid process and underneath exercise attire. Resting heart rate as well as changes in heart rate during exercise and 1.5 min after the test concluded (i.e., the recovery pulse) were measured. Heart rate monitors sampled participant responses at 5-s intervals and were transmitted to a smartwatch (Polar, Polar Electro; Kempele, Finland). The PEI was calculated using the following formula [29]: PEI=(100 L)/(5.5 p), where L is the duration of the test (L=300 s)

in heart rate during exercise and 1.5 min after the test concluded (i.e., the recovery pulse) were measured. Heart rate monitors sampled participant responses at 5-s intervals and were transmitted to a smartwatch (Polar, Polar Electro; Kempele, Finland). The PEI was calculated using the following formula [29]: PEI=(100 L)/(5.5 p), where L is the duration of the test (L=300 s) and p is the number of heartbeats in the 1.5 min after the participant completed the test. 2.5. Motor Performance The following tests were used to determine the motor component: the 4 10 m shuttle run test to evaluate agility and the vertical jump test to evaluate the power of the lower limbs. The 4 10 m shuttle run test (agility) was performed according to a previous description [30]. Two parallel lines were drawn on the oor 10 m apart. The participants ran as fast as possible from the starting line to the other line and returned to the starting line, crossing each line with both feet every time. The researcher was situated at the starting line and stopped the stopwatch when the participants crossed the line with one foot. The time taken to complete the test was recorded to the nearest tenth of a second. Participants wore sports shoes and performed the test twice with a 5-min rest in between, and the best time was selected. The power of the lower limbs was assessed using the static vertical jump procedure in the vertical jump test, in which a static position with a knee exion angle of 90 was maintained for 2 s before a jump attempt without any preparatory movement. All jumps were executed with the hands on the hips. Three jump attempts were performed, separated by 15-s intervals. The jumps were performed on a g-force tracker (Vert Jump; VERT, Fort Lauderdale, FL, USA) with the obtained ight time (t) being used to estimate the height of the rise of the body's center of gravity (h) during the vertical jump (i.e., h=gt 2 /8, where g=9.81 m/s 2 ). The best attempt was used in our data analysis. All

The jumps were performed on a g-force tracker (Vert Jump; VERT, Fort Lauderdale, FL, USA) with the obtained ight time (t) being used to estimate the height of the rise of the body's center of gravity (h) during the vertical jump (i.e., h=gt 2 /8, where g=9.81 m/s 2 ). The best attempt was used in our data analysis. All measurements as measured in our study parameters met H-RF (health-related tness) conception and constitute morphological, muscular tness and endurance, cardio-vascular endurance, and motor abilities (speed and agility) health-related tness components. The scienti c rationale for the selection of all of these tests, as well as their reliability in young people, have previously been published [17,27,28].

Int. J. Environ. Res. Public Health2020,17, 876 5 of 11 2.6. Intervention During one PE lesson per week, participants followed the HIIT exercise regimen based on the Tabata training protocol [31]. A PE lesson in the current intervention started with organizational activities in the group and motivating students to actively participate. Next, a standardized 10-min warm-up consisting of 5 min of slow jogging followed by 5 min of stretching (dynamic and static) of major muscle groups was performed. The main part of the lesson was the HIIT training based Tabata protocol, with a total time of 14 min. This training was divided into three sessions, each lasting 4 min. Each session based Tabata protocol (20 s work/10 s rest) consisted of eight cycles of two exercises. Each cycle started with a maximum intensity exercise lasting for 20 s, in which the participant was motivated to perform as many repetitions as possible of a given exercise involving large muscle groups of the entire body (np. narrow stance squat, butt kicker, toe touches, lunges, mountain climbers, jumping jacks, standing abs twist, squat to side), which was followed by a 10-s active rest in the form of a low-intensity exercise (i.e., skipping without rope, jumping without rope, walking). The cycles were repeated without any rests between them. The total duration of each session was 4 min. There was a 1-min passive rest between each session during which no exercises were performed. After the Tabata training, the nal part of the training, including exibility and relaxation exercises, was performed for several minutes. All the exercises were prepared by the authors (for the purpose of the experiment), recorded, and played during the PE lesson on a screen to ensure that the times of exercise and rest were implemented accurately. To verify the exercise intensity during the Tabata training, the maximum heart rate (HRmax) of the participants was determined according to the formula proposed by Tanaka, et al. [32] HRmax=208 0.7 “age” (age=16 years in this study). A calculated HRmaxof 197 bpm was used to calculate the high-intensity exercise range of 75%–80% (145–157 heartbeats/min). During the

Evaluates Tabata training effects on body composition and fitness in adolescents.