Good physical fitness is a necessary condition for an effective life, not only to help individuals work efficiently such as when doing housework or driving a car but also to enjoy leisure time or deal with emergencies (1, 2). For children, one of the ways to improve physical fitness was through the school system. It was previously reported that physical education (PE) in schools was considered the ideal intervention point to improve the current and future population health by increasing children’s physical fitness levels (3, 4). However, the leader of the Chinese national primary and secondary school PE and health curriculum standards development group had argued that in China, PE had evolved into a “safety class,” “discipline class,” and “military class” that emphasized consistency in learning and practicing physical skills and keeping students in a specific position for long periods, which results in children not even sweating at the end of a class (5). Such PE benefits neither public health nor the students’ physique (6). Faced with the problems of the traditional PE syllabus, there is an urgent need to conduct an in-depth study of PE to find solutions to improve the quality of the PE syllabus and effectively increase students’ physical fitness. Ji (7) proposed a healthy physical education curriculum model (HPECM), which stipulated that each class should include 20 min of skill exercise and 10 min of physical fitness exercise. The 10 min of physical fitness exercises were primarily intended to address the traditional PE lesson which did not include any time dedicated to physical fitness (6). Besides the allocation of time, the program should comprise physical fitness exercises which were diversified, interesting, and act as compensatory methods and means to deal with the traditional PE lesson of learning only one motor skill and developing only a specific body part in each lesson.

One way to improve physical fitness is through functional training. Functional training began in sports medicine, then was introduced to the field of athletic training by coaches, subsequently being introduced to gyms, where the general public had access to a vast array of methods associated with it (8). Nowadays, functional training has become a fitness hotspot. Since 2007, according to the global fitness trend surveys conducted by the American Society of Sports Medicine (ACSM), functional training has always been listed among the Top 20 fitness regimes (9–23). Most importantly, functional training was found to provide health benefits and could be used to improve the ability to perform a variety of activities of daily living at home, at work, or during play, without the risk of excessive injury or fatigue (24). Besides health benefits, functional training could contribute to performance benefits in the areas of speed, strength, and power as pointed out by Boyle (25). Finally, the advantages of needing little space, equipment, and time also contribute to its popularity (26). Given the superiorities of functional training, some researchers tried to transplant functional training to school PE. For example, Oliver and Brezzo (27) examined the effects of functional balance training on female collegiate and found that functional balance training could strengthen the core while simultaneously balancing activities, which not only aided functional performance but also helped prevent injury. Likewise, Lasković et al. (28) compared the effects of functional training and PE classes on the physical fitness of primary school girls and found that both training methods had a positive impact on the physical fitness of the students. Despite these efforts, the literature on the use of functional training in PE curricula is limited, particularly in primary schools.

This study was conducted to design and develop a 12-week functional training program that could be incorporated into existing PE lessons. The design and development were based on the ADDIE model. The study could verify the feasibility of incorporating functional training into the primary school PE curriculum as well as provide a reference for other researchers who were interested in improving the effectiveness of PE.

The study mainly used the ADDIE framework to guide the process of designing and developing a functional training program. The ADDIE framework is a process model developed for the military and enthusiastically adopted by the army due to its clear delineation of instructional design steps, namely Analysis, Design, Development, Implementation, and Evaluation (29, 30). The generic and dynamic process within five stages allowed instructional designers to use the model with flexibility, in terms of how different steps or procedures were performed, which has made it one of the most popular and frequently cited instructional design models (29, 31) and applied in various disciplines (32). In education, it has been referred to in the subject of English language (33–35), chemistry (36) and physics (37), as well as in a nursing curriculum (38). Additionally, some studies had applied the ADDIE model to the PE curriculum. For example, Wei (39) shared how the “micro-lecture” designed and produced based on the ADDIE model was applied to the teaching of PE in schools and was favored by the teachers and students. Yan (40) also discussed how to improve the level of social sports instructors by using the ADDIE model to design training courses.

The objectives of PE for primary school students were that through the study of PE and health curriculums, students would master various physical training methods, and could actively participate in various physical exercises, and their physical fitness levels would be significantly improved, meeting the corresponding requirements of the 2014 revised Chinese National Student Physical Fitness Standard (CNSPFS) (51).

According to the 2014 revised CNSPFS test conducted on the students, the current status of students’ fitness showed that the 50 m sprint dropped sharply which needed to be improved (54). Combined with the results of the thematic analysis of the five expert interviews using NVivo software (Table 2), the final 36 functional training programs were drafted and developed, which included three stages: 2 weeks of basic stage mainly used to learn the base movement pattern; 5 weeks of Advance stage I; and 5 weeks of Advance stage II. Video recordings of the corresponding movements of the functional training program were made to assist students in learning so that students had an intuitive understanding of movements. The summary functional training program that was drafted and developed can be found in Table 3. The complete program for each of the 36 sessions can be found in an experimental study, which also includes the arrangement of the control group (69).

To fill the gap in the application of functional training in primary school PE, this study designed and developed a 12-week functional training program, that could be incorporated into PE lessons, to improve students’ physical fitness. The design and development were guided by the ADDIE model. The applicability and acceptability of the program were evidenced by both the positive feedback from experts and students and the significant changes in students’ physical fitness after implementation.

When experts gave feedback on the program, most of them were positive about the program. They used words that generally express positive attitudes and express approval of the program, such as ‘全面’ (comprehensive), ‘可操作性’ (operability), and ‘可行性’ (feasibility).

Other than feedback from experts, it was also important to get feedback from students, in terms of their interest in the program. Interest is both a psychological state of attention and affection toward a particular object or topic and an enduring predisposition to reengage over time (75). It had long been recognized as a motivation factor that guides children to learn (76, 77) and a meta-analysis had reported that situational interest was a primary motivator for students to engage in PE (78). Most PE teachers focused on controlling the characteristics of situational interest to stimulate students’ situational interest, which had been proven to be positively correlated with learning engagement, to influence learning engagement (79, 80). In this study, the feedback on the students’ situational interest showed that the novelty and exploratory dimensions scored the highest. Novelty meant that the program had more novelty, and could attract participants’ attention (81). Exploratory intention indicated that participants were willing to explore a certain way of the program, which was a prerequisite for maintaining interest. This finding was in line with a study about the process of interaction between the learner and the learning content (78). The authors pointed out that learners felt the novelty and challenge of the learning content, that learners’ exploration intentions were awakened, and at the same time, they could experience a sense of enjoyment, which could stimulate their situational interest. Besides novelty and exploration, the other dimensions, such as attention demand, instant enjoyment, and total interest also had scores that were larger than 4, which meant that the program led to a high level of situational interest. As Zhou et al. (82) pointed out, functional training exercises were not only easily adapted to individual fitness levels, which could lead to a greater sense of mastery and enjoyment, but they were also fun, novel, and challenging due to the use of a variety of small, portable equipment and rapid changes in activity pace.

Conversely, the challenge dimension had the lowest score. However, it is possible that this dimension had little influence on the program as in a follow-up study to Chen and Darst (83), a path analysis had revealed that (a) instant enjoyment and exploration highly contributed positively to situational interest, (b) novelty and attention demand partially contributed positively, and (c) physical challenge contributed little (84). In this study, the participants might have been confident that they could complete the program, but it did not influence their interest in it.

As for the physical fitness performance, the results of the physical fitness test indexes showed that the baseline scores were significantly different from the post-test scores. All students had a positive growth rate and improved their physical fitness performance after the 12-week functional training program. Participants’ BMI, a sensible indication of children’s overall adiposity (85), increased dramatically but stayed within normal weight ranges (53), possibly due to increased muscle mass (86). Participants’ flexibility (sit and reach), muscular strength and endurance (timed sit-ups and timed rope-skipping), and speed (50 m sprint) all improved. It appeared that the proposed design and arrangement of functional training incorporated into PE lessons were effective in improving the students’ physical fitness. The results of this study were consistent with a systematic review that reported that functional training could improve speed, muscle strength, muscular endurance, and other physical variables (87).

This study is not without some limitations. The goodness of movement completion is influenced to some extent by the cognitive level of students in the process from movement understanding to movement execution. In addition, in the selection of movements in the program, some simple and easy movements were chosen, which to some extent reduced the intensity of the exercises (69). Finally, this study mainly focused on the control of PE classes and did not control for extracurricular activities, which may have some influence on the results of the study.

Children, whose health set the stage for adult health, are vital to the nation’s present and future (88). Schools, as the main place for children to improve their physical fitness (78), urgently need to conduct an in-depth study of the PE lessons to find solutions to improve the quality of the PE curriculum to improve students’ physical fitness effectively. This study was aimed at the physical fitness part of the HPECM. Under the scientific guidance of the ADDIE model, the design results of this research had not only been recognized by experts and students but also played a positive role in improving students’ physical performance. Subsequent research endeavors will implement this program in different grades of PE lessons in primary schools, conduct comprehensive teaching experiments, hope to address potential limitations, enhance the adaptability of the program further, obtain reliable and valid results, and open a window for more research on improving PE curriculum quality.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by The University Malaya Research Ethics Committee (Approval number: UM.TNC2/UMREC–667). The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin.

HL and JC: conceptualization and methodology. HL: data curation, software, and writing – original draft. JC: supervision and writing – review and editing. All authors contributed to the article and approved the submitted version.