The Effects of Resistance Training Interventions on Weight, Body Mass Index, Body Fat Percentage, and Flexibility in College Students: A Comparison Between Sports and Non-Sports Students

Background. Resistance training is an effective form of exercise that promotes healthy body weight regulation and enhances flexibility. However, discrepancies exist regarding the varying impacts of resistance training based on individuals’ training status across different fitness components, such as body composition and flexibility. Objectives. The primary objective of this study is to assess whether there are significant differences in the outcomes of resistance training responses between trained and untrained groups concerning body composition and flexibility. Materials and methods. This experimental resistance training study involved 60 male students (age = 20.83 ± 0.85 years old) from the same university. The participants were divided into two groups based on their training status: a trained group (S; n = 30) and an untrained group (NS; n = 30). Both groups underwent an identical training regimen, consisting of three sessions per week over a total of four weeks or 12 training sessions. Results. Significant differences were observed in the paired sample T-test analysis between pre-test and post-test results in the untrained group for body weight (t = 7.940, p < 0.001, d = 1.45), body mass index (t = 7.579, p < 0.001, d = 1.38), body fat percentage (t = 9.733, p < 0.001, d = 1.77), and sit-and-reach flexibility (t =-7.714, p < 0.001, d =-1.40). Similarly, the trained group showed significant changes in body weight (t = 2.644, p = 0.013, d = 0.483), body fat (t = 2.561, p = 0.016, d = 0.351), and flexibility (t =-2.543, p = 0.017, d = 0.351), while no substantial difference was found in body mass index (t = 1.925, p = 0.064, d =-0.464). Conclusion. The study found that using resistance training protocols targeting weight reduction with 60-70% of 1 Repetition Maximum (RM) over a one-month intervention period, without stringent calorie restriction, significantly decreased weight and BMI while enhancing flexibility. Notably, regardless of training status disparities, the untrained group demonstrated more expressed improvements compared to the trained group, indicating the influence of training status on response variations to training stimuli.