High-Intensity vs Moderate Training Impact on Male Teens: A Study

High School Students in Physical Fitness Study

Grade 9 male students at high school participated in a study on physical fitness. Prior to the study, parental or guardian consent was obtained for every participant. The inclusion criteria for this study required participants with normal intelligence, no underlying cardiovascular or metabolic diseases, and the ability to engage in regular physical activities. Students with any existing chronic illnesses or physical disabilities that could hinder exercise performance were excluded from this study.

Design of the Physical Fitness Study

Students in this study on improving physical fitness were randomly divided into an experimental group and a control group. The experimental group engaged in one session of High-Intensity Interval Training (HIIT) and two sessions of Moderate-Intensity Continuous Training (MICT) each week. In contrast, the control group participated in three sessions of MICT weekly. Both groups maintained an equivalent total weekly exercise duration to ensure comparability. Participants were instructed to consistently sleep for about 8 hours per night and maintain a healthy, balanced diet throughout the intervention period.

Before the intervention, all participants underwent baseline assessments, which involved a series of physical fitness tests. These included a lung capacity test using a spirometer, a 50-meter sprint test, a standing long jump test, and a 1000-meter run test. Furthermore, academic performance was evaluated through the average grades of all subjects, and anxiety levels were measured using the Zung Self-Rating Anxiety Scale (SAS)¹⁴. The same assessments were repeated after the 12-week intervention to evaluate the effects of the training programs. All measurements were conducted under standardized conditions to ensure reliability and validity. Trained personnel carried out data collection to minimize potential biases and enhance the accuracy of the results.

Random Allocation of Participants

Participants were randomly assigned to either the experimental or control group using a simple random allocation method. To ensure an unbiased and fair distribution of participants across the two groups, group labels (experimental or control) were randomly drawn from a container. The professionals responsible for measuring outcomes were blinded to the group allocation to minimize bias.

Physical Fitness Intervention Program

The experimental group performed a combination of HIIT once per week and MICT twice per week. The HIIT program consisted of various exercises, including high knees, jumping jacks, lunge jumps, and mountain climbers, push-ups, squat jumps, planks, and Russian twists. The MICT program included four aerobic exercises targeting sustained moderate-intensity cardiovascular endurance. The participants were trained by certified exercise professionals before the formal intervention to ensure proficiency in executing the exercises.

The intervention took place outdoors on the campus sports field, three times per week on non-consecutive days, with weekends allocated for rest. The control group engaged exclusively in MICT, three times per week, at the same intensity.

Ethics Approval for the Study

This study followed the ethical guidelines set forth in the Declaration of Helsinki, with approval from the Institutional Review Board of Guizhou Medical University. Written informed consent was obtained from each participant and their parent or legal guardian prior to study initiation. Participation was voluntary, with the right to withdraw at any stage without any repercussions. Confidentiality of all personal data was strictly maintained throughout the study.

Statistical Analysis of the Data

IBM SPSS statistics (v29.0.2.0.) was used for statistical analyses, with a significance level set at P < 0.05. Various statistical methods were utilized depending on the distribution of the data. Continuous variables were reported as mean (SD) for parametric tests and median (Q1; Q3) for non-parametric tests. Categorical data were analyzed using the chi-square test for independence, with the McNemar test applied to assess differences in paired categorical data within the same group.

Calculation of Sample Size

The sample size for this study was calculated based on the effect of HIIT on cardiorespiratory function as reported in a previous meta-analysis. A power analysis was conducted using an effect size of 0.8, a significance level of 0.05, and a power of 0.80, utilizing G*Power 3.1.9.4 software. The analysis determined that a minimum of 26 participants per group would be required to achieve adequate power to detect a significant effect. To account for potential attrition and to strengthen the reliability of the results, 30 participants were recruited for each group.