The Influence of Burpee on Endurance and Short-Term Memory of Adolescents

e purpose of this study was to assess the effect of the Burpee exercise on the endurance and short-term memory of adolescents aged 15–16 years. Methods—The experiment was performed in a coeducational school in Kirov (Russia). The four-month study involved 52 adolescents of both genders. During the study period, 30 physical education lessons were held in each class. Adolescents from the control group were involved in a typical program (also aimed at improving endurance), and adolescents from the experimental group additionally performed the Burpee exercise. Endurance in adolescents was assessed by means of an “all-out” Running 2000 m test, and short- term memory was assessed by means of the Jacobs test (tests were performed before and after the programs). Results—An analysis of

group were involved in a typical program (also aimed at improving endurance), and adolescents from the experimental group additionally performed the Burpee exercise. Endurance in adolescents was assessed by means of an “all-out” Running 2000 m test, and short- term memory was assessed by means of the Jacobs test (tests were performed before and after the programs). Results—An analysis of variance revealed an interaction effect (F = 28.733, p 2= 0.578 andp< 0.001, and F = 104.353, p 2= 0.676 andp< 0.001 for the Running 2000 m test and the Jacobs test, respectively). The control group improved by 1.9% (p> 0.05) in the Running 2000 m and by 5.5% (p> 0.05) in the Jacobs test. In the experimental group, both improved signi cantly by 8.6% (p< 0.05) in the Running 2000 m test and by 26.0% (p< 0.05) in the Jacobs test. Conclusion—The Burpee exercise could be included in physical education classes to improve endurance and short-term memory in 15–16-year-old. Keywords:exercise; distance-running; cognition; youth 1. Introduction Almost everybody shares the aim of improving their physical and cognitive abilities. In particular, teachers and coaches are always in search of methods—includingexercises—that are as effective as possible to achieve this aim. Among the most well-known speci c exercises is the Burpee, which was invented by the America physiologist Royal Huddleston Burpee in New York in the late 1930s [1]. The Burpee exercise has become so popular that people from all over the world take part in online challenges held over the Internet with the goal of performing the maximum number of repetitions during a certain time interval. The Burpee is an exercise that places a particularly high burden on the metabolic machinery due to the large group of muscles involved in its practice [1]. The Burpee exercise can be performed anywhere and without any speci c gym tool [2,3]. If performed with adequate technique, the Burpee exercise can support the safe development of the muscles of adolescents as it is easily performed with one's own weight. Strength training in adolescence is an object of discussion because of its alleged risk to harm a

[1]. The Burpee exercise can be performed anywhere and without any speci c gym tool [2,3]. If performed with adequate technique, the Burpee exercise can support the safe development of the muscles of adolescents as it is easily performed with one's own weight. Strength training in adolescence is an object of discussion because of its alleged risk to harm a person's growth and development [4]. In fact, there is some controversy surrounding the appropriateness of performing resistance exercises in adolescents. There is a widely Int. J. Environ. Res. Public Health2022,19, 11778.

Int. J. Environ. Res. Public Health2022,19, 11778 2 of 8 held inaccurate belief that strength training, when performed during puberty and/or adolescence, can hamper one's growth by damaging growth plates. However, strength training is safe and does not negatively impact the growth and maturation of pre- and early-pubertal individuals [5,6]. Its bene ts include an increase in strength, speed, and power; improved body composition; stronger bones; and a reduction in injury rates [7,8]. Despite its worldwide spread, there are no scienti c studies showing the Burpee exercise as an effective element of physical activity for adolescents. It is likely that such an activity will be more effective within an individual approach for each student [9,10]. Furthermore, the scienti c literature shows that physical activity has a positive effect on the cognitive performance of adolescents of different ages [11], in particular at 15–16 years of age, viz., when attending 10th grade or the rst year of college [12–14]. Considering the sensitive periods of development of physical qualities such as strength, speed-strength abilities and endurance, the age of 15–16 years was determined to be best for the study (this corresponds to the 9th grade in regular school progression). At this age, there is a rather intensive development of the muscle mass of adolescents and notable development of most physical qualities, especially endurance [15,16]. If at primary school age, a differentiated approach and coordination training prevail, later, at secondary school age, an individual approach is more often used. The research hypothesis was that adding the Burpee exercise to traditional physical education lessons at school would lead to an improvement to both endurance and short-term memory. The aim of this study was to assess the effect of the Burpee exercise on the variables of endurance and short-term memory in adolescents aged 15–16 years. The implicit reasoning supporting our aim was that exercises such as the Burpee are different from many other single gym exercises. Rather, the Burpee exercise has, in our opinion, a double nature (read Section Execution Technique below). Namely, the Burpee exercise appears to be particularly demanding of metabolic energy due to

endurance and short-term memory in adolescents aged 15–16 years. The implicit reasoning supporting our aim was that exercises such as the Burpee are different from many other single gym exercises. Rather, the Burpee exercise has, in our opinion, a double nature (read Section Execution Technique below). Namely, the Burpee exercise appears to be particularly demanding of metabolic energy due to its fast-paced jumping and weight-bearing stages. Furthermore, its correct execution requires continuous and conscious motor control over its different stages, which are very different from each other and involve all the main body segments (thus, maybe, in some way, mirroring short-term memory capability [17]). It is noteworthy to recall that Burpee training was already deemed to be associated with more positive psychological responses than other commonly practiced high-intensity exercises [18]. Therefore, we expected that matching training time between an experimental group and a control group and adding the Burpee exercise to a usual physical education program would further improve both endurance and short-term memory. 2. Materials and Methods 2.1. Participants Fifty-two adolescents aged 15–16 years (height 167.4 8.9 cm, mass 56.2 8.5 kg), who studied in a regular Russian school in the city of Kirov took part in this study. They were boys and girls who studied at grade 9 (in two different classes: 9a and 9b). During the study period, physical education classes were set so that other physical activities of the students did not affect the test results. That is, the students who took part in the study did not exercise additionally. The students were divided into a control group (CG) and an experimental group (EG). Regardless of gender and level of physical tness, only those adolescents who were admitted to physical education lessons by a doctor without any of the following restrictions for health reasons took part in the study. Students' non-inclusion criteriawere: joint problems (especially at knee and hip), chronic heart disease or high blood pressure, and being excessively overweight (more than 30% of the normal weight). In total, out of 32 students studying in 9a, 25 completely healthy—as assessed by the school's physician—students (13 boys

any of the following restrictions for health reasons took part in the study. Students' non-inclusion criteriawere: joint problems (especially at knee and hip), chronic heart disease or high blood pressure, and being excessively overweight (more than 30% of the normal weight). In total, out of 32 students studying in 9a, 25 completely healthy—as assessed by the school's physician—students (13 boys and 12 girls) were admitted to the study as the CG. In the same way, out of 33 students studying in 9b, 27 students (13 boys and 14 girls) took part in the study as the EG. All procedures met the ethical standards of the 1964 Declaration of Helsinki and were approved by the local university ethics committee. Informed consent

Int. J. Environ. Res. Public Health2022,19, 11778 3 of 8 was obtained from all the parents of the adolescents included in the study. Students were free to withdraw from the experiment at any time. 2.2. Procedure Research was performed in a co-educational school in Kirov (Russia) from 1 September to 30 December 2021. School physical education lessons took place twice a week, lasting 45 min each. All lessons were monitored. A total of 30 physical education lessons were performed, always at the same time and on the same weekdays. A usual physical education program for students at grades 1–11 was administered to the CG [19]. The purpose of the physical education curriculum was to form the basics of a healthy lifestyle among school students and the development of creative independence through the development of motor activity. The realization of the purpose of the curriculum correlated with the solution of the following educational tasks: 1. Improving knowledge on the importance of physical culture for strengthening human health and on its positive impact on human development (physical, intellectual, emotional and social). 2. Strengthening the health of schoolchildren through the development of physical qualities and increasing the functionality of the life-supporting systems of the body. 3. Improving vital skills and abilities through learning outdoor games, physical exercises and technical actions from basic sports. The experimental group followed the same program but additionally performed the Burpee exercise in each lesson (in Table, differences from the control group, which was engaged in the ordinary program for the whole duration of each lesson, can be observed; i.e., lessons probably resulted in a few differences among the groups in terms of training volume). Table 1.Over-time Burpee exercise administration features for adolescents aged 15–16 years. Number of Series Activity September October November December 1st series Burpee 60 s 90 s 120 s 120 s Time of rest 60 s 60 s 90 s 60 s 2nd series Burpee 60 s 90 s 120 s 120 s Time of rest 90 s 90 s 120 s 90 s 3rd series Burpee 60 s 90 s 90 s 120 s

Activity September October November December 1st series Burpee 60 s 90 s 120 s 120 s Time of rest 60 s 60 s 90 s 60 s 2nd series Burpee 60 s 90 s 120 s 120 s Time of rest 90 s 90 s 120 s 90 s 3rd series Burpee 60 s 90 s 90 s 120 s Time of rest 120 s 120 se 120 s 120 s Total time 7 m 30 s 9 m 11 m 10 m 30 s 2.3. Execution Technique If we split the whole Burpee exercise into separate stages, then it consists of four main simple exercises: squat, plank, push-up and jumping up. In more detail, the technique of the traditional Burpee exercise is as follows [20]: 1. 2. 3. 4. 5. 6. Particular attention was paid to performing the correct technique rather than aiming at a high number of repetitions. Nevertheless, a suf ciently high intensity was required to obtain a signi cant effect. In case of dizziness, nausea or chest pain, the exercise had to be stopped.

Int. J. Environ. Res. Public Health2022,19, 11778 4 of 8 2.4. Exercise Stress The exercise was performed for a given time, and an operator counted the repetitions of each student (from 15 to 25 repetitions per minute). The Burpee exercise was performed at the end of the main part of the lesson. Overtime, exercise administration followed the principle of gradualism [21]. The administration features of the Burpee exercise over time are shown in Table. It should be noted that the Burpee exercise administration features were chosen considering the well-being of the majority of adolescents involved. For example, during the rst month, a 60 s period of the Burpee exercise was ineffective, but a longer exercise time was not tolerated by most of the students. Gradually, the Burpee exercise time increased, and the rest time decreased. However, at the end of the experimental period, most of the students could not physically endure more than three series, as described above. At the same time, it was important that the Burpee exercise did not interfere with the implementation of the regular main physical education curriculum at the school. 2.5. Test Procedure In the last lesson before the start of the study period and in the rst lesson after the end of the study period, all adolescents took two control tests. General endurance was assessed by means of the Running 2000 m test [19]. The test consisted of running 2 km on the track of the athletics arena. Before the start of the test, the students were in a standing position. At the command “Start!”, the students took their place behind the starting line. At the command “March!”, they started running. The results were recorded using a chronometer in minutes and seconds with an accuracy of 1 s. Short-term memory was determined by means of the Jacobs test [22]. This well-known test has been repeatedly positively assessed over time for its validity and reliability [23]. There were four squares on a paper sheet. Each square had numbers with gures in random order and numbers of digits in ascending order over each column (Table). Table

accuracy of 1 s. Short-term memory was determined by means of the Jacobs test [22]. This well-known test has been repeatedly positively assessed over time for its validity and reliability [23]. There were four squares on a paper sheet. Each square had numbers with gures in random order and numbers of digits in ascending order over each column (Table). Table 2.Material for determining short-term memory. First Square Second Square 7428 7364 96538 95837 694103 104735 3620395 0987295 20315631 03827547 738602126 930472659 4839039516 9408726351 The third square Fourth square 5829 9813 73620 93846 831965 019462 0946283 9273657 72840586 62539506 637495024 726304957 1048375629 7076241546 In short, the test was as follows: the teacher slowly called aloud the gures of each line (one square after the other starting from the rst). After each line, the adolescents wrote the numbers in the order in which the teacher told them. Short-term memory scores were calculated using the formula A + C/4, where A was the digit number of the longest line that was written correctly, and C was the number of correctly written lines shorter than the longest correctly written. The reason for the teacher to read all the numbers in all the squares was to provide the adolescents with the greatest number of opportunities to remember the numbers. For example, if an adolescent wrote all the rst lines (A = 4), they received a 4-point score (C = 0, A + C/4 = 4).

Int. J. Environ. Res. Public Health2022,19, 11778 5 of 8 2.6. Statistical Processing of Results The results were recorded as means and standard deviations. Statistics was performed with SPSS 20.0 (IBM, Armonk, NY, USA). Normality of results was assessed and con rmed by means of the Shapiro–Wilk test (threshold withp< 0.05). The null hypothesis for the values was assessed by means of the multivariate Pillai test.T-test was used to compare the two groups for the Running 2000 m test and Jacobs test at baseline conditions. The between-group differences in Running 2000 m test and Jacobs test over-time were analyzed using a two-way analysis of variance (ANOVA) with time as a repeated-measure factor (two levels, pre- and post-training) and group as a between factor (two levels, CG and EG) with Bonferroni post hoc test, if the sphericity was not violated. The ANOVA effect size was evaluated with partial eta squared ( p 2) and classi ed as follows: small, <0.06; medium, 0.06–0.14; and large, >0.14 [24]. The magnitude of differences between variables was interpreted using standardized effect size (Cohen'sd): <0.1, no effect; 0.20 < 0.40, small effect; 0.50 < 0.70, intermediate effect; 0.80 < 1.0, large effect. Moreover, upper and lower 95% con dence intervals of the difference (95% CI) were calculated. The statistical signi cance level was set atp< 0.05. 3. Results The Running 2000 m test and Jacobs test initial values were similar (p> 0.05). The drop-out rate was nil. First, the Shapiro—Wilk test showed a normal distribution. For the Running 2000 m test,p= 0.918 with W = 0.940 andp= 0.918 with W = 0.942 for the CG and the EG, respectively. Similarly for the Jacobs test,p= 0.918 with W = 0.936 andp= 0.918 with W = 0.959 for the CG and the EG, respectively. The sphericity was not violated. At baseline conditions, no signi cant differences were found between groups for the Running 2000 m test (p= 0.471) and the Jacobs test (p= 0.063). All data are reported in Table. Table 3.The tests results for all groups. Test Control Group (n = 25) Experimental Group (n = 27)

the CG and the EG, respectively. The sphericity was not violated. At baseline conditions, no signi cant differences were found between groups for the Running 2000 m test (p= 0.471) and the Jacobs test (p= 0.063). All data are reported in Table. Table 3.The tests results for all groups. Test Control Group (n = 25) Experimental Group (n = 27) Before After % d p Before After % d p Running 2000 m (min.s) 9.95 1.16 9.76 1.04 1.9 1.8 Large p> 0.05 10.19 1.21 9.27 0.67 8.6 5.0 Large p< 0.05 Jacobs (pt) 6.2 0.6 6.5 0.4 5.5 3.1 Large p> 0.05 5.9 0.4 7.4 0.5 26.0 10.3 Large p< 0.05 Then, the multivariate Pillai test was used to preliminarily test the null hypothesis for the values. The test results are V = 0.635 withp< 0.001 and V = 0.676 withp< 0.001 for the Running 2000 m test and the Jacobs test, respectively. An analysis of variance was operated to assess interaction effects. The analysis of variance revealed interaction effects of F = 28.733, p 2= 0.578 andp< 0.001, and F = 104.353, p 2= 0.676 andp< 0.001 for the Running 2000 m test (d= large effect) and Jacobs test (d= large effect), respectively. As shown in Table, the performances in both tests improved signi cantly only in the EG. In adolescents of the CG, the scores in the Running 2000 m test improved by 1.9% (p> 0.05, not signi cantly) and the scores in the Jacobs test increased by 5.5% (p> 0.05, not signi cantly) compared to before the start of the study period. Differently, for adolescents in the EG, the scores in the Running 2000 m test improved by 8.6% (p< 0.05), and the scores in the Jacobs test increased by 26.0% (p< 0.05) in respect to before the intervention. 4. Discussion First, this study unexpectedly highlighted the lack of effectiveness of the administered physical education program to increase running endurance, as demonstrated by the results in the control group (CG) shown in Table. It was not expected that such a program would speci cally increase short-term

Burpee exercise improves endurance and memory in adolescents.