INTRODUCTION
In modern society, the issue of insufficient physical activity among university students is becoming increasingly serious [1]. This lack of activity has been associated with a heightened risk of decreased physical fitness, obesity, and musculoskeletal disorders [2]. Particularly, many students experience a significant decline in physical activity upon entering university, which can lead directly to deteriorating health and a reduced quality of life in the long term [3]. Against this backdrop, the importance of strength training has been emphasized [4]. Resistance training enhances muscle hypertrophy and maximal strength [5-7], while power training, performed at high velocity with low resistance, improves neuromuscular efficiency and fast-twitch fiber recruitment [8,9]. As these modalities differ in stimulus, their effects on maximal strength also differ. Maximal strength, commonly measured via one-repetition maximum (1RM) [10-12], is a key indicator of performance. Therefore, this study aims to compare the effects of resistance and power training on university students’ maximal strength.
A unique aspect of this study is the use of identical exercises across two phases. Phase 1 applied the “3-second rule” for controlled repetitions, while phase 2 focused on high-speed repetitions within 20 seconds. Muscle strength and body composition were measured pre-, mid-, and post-intervention to assess training effects.
METHODS
This study involved 57 male and female students from Sogang University (mean age, 22.04 years). This study was approved by the Institutional Review Board at Sogang University (SGUIRB-A-1808-44) and all participants signed an informed consent form. Body composition (height, weight, muscle mass, %body fat) was measured using InBody (InBody Co.) at three time points (Table 1).
Experimental design and procedure
A 12-week repeated-measures design was used, with 24 sessions held twice weekly. The first 6 weeks focused on resistance training with controlled concentric and eccentric phases (“3-second rule”), and the last 6 weeks on power training with explosive movements.
Participants were assessed at:
- T1 (pre): 1RM/repetition test+InBody
- T2 (mid): post-resistance training
- T3 (post): post-power training
Exercise program structure
Twelve exercises were used:
- 1RM-based (8): leg press, leg curl, leg extension, shoulder press, chest press, fly, lat pull down, seated row
- Repetition-based (4): leg raise, sit-up, back extension, kettlebell
In phase 1, 1RM exercises followed the 3-second tempo, and repetitions were counted over 1 minute. Repetition-based exercises were done at a self-paced max effort for 1 minute. In phase 2, all exercises were performed as fast as possible for 20 seconds using the same load. Sessions included warm-up and cooldown, supervised by exercise specialists.
Statistical analysis
SPSS ver. 25.0 (IBM Corp.) was used. Means, standard deviations, repeated measures ANOVA, and paired t-tests were applied. For statistical analysis, Friedman repeated measures ANOVA (a non-parametric test) and paired t-tests were conducted for each exercise type. Missing data were handled by listwise deletion. Significance was set at α=0.05.
DISCUSSION
This study investigated the effects of resistance and power training on maximal strength (1RM), endurance performance (repetition-based), and body composition (skeletal muscle mass and body fat percentage) in a population of university students. Among the 12 exercises evaluated, 11 showed significant improvements, with particularly notable performance gains observed in exercises such as leg extension, chest press, and sit-up. The average improvement rate for the 1RM-based exercises exceeded 100%, indicating a pronounced effect of the training intervention over a relatively short period.
Resistance training has been shown to enhance muscle hypertrophy, neuromuscular efficiency, and muscle fiber cross-sectional area [13]. In contrast, power training emphasizes explosive speed and fast-twitch fiber recruitment, aiming to maximize repetitions within a short time window. In this study, both forms of training contributed to improved strength outcomes. Given that resistance and power training were applied sequentially rather than as isolated sessions, the observed effects may be interpreted as resulting from a combined or hybrid training model.
Skeletal muscle mass changes differed by sex; male participants generally showed consistent increases, whereas female participants displayed maintenance or slight decreases after the second measurement. This pattern is likely related to hormonal differences [14] and muscle fiber distribution characteristics, aligning with previous findings that men exhibit more rapid muscular adaptations to high-load training. Body fat percentage gradually decreased in both sexs, presumably due to increased energy expenditure and enhanced metabolic efficiency.
Not all exercises showed improvement, however. The kettlebell exercise was the only activity that exhibited a decline in average repetitions, a result that was not statistically significant. This outcome may be attributed to the technical difficulty of the movement, insufficient individual proficiency, or inconsistencies in exercise intensity prescription [15]. Accumulated fatigue and reduced movement accuracy may also have influenced the decrease in performance [16]. These findings highlight the need to reassess exercise-specific responsiveness and ensure clearly defined quantification criteria during program design.
Furthermore, among the repetition-based exercises, both leg raise and back extension did not exhibit statistically significant changes. This may be attributed to the inherent difficulty in providing a uniform training stimulus across participants. Specifically, the leg raise exercise involves lower abdominal activation without upper body stabilization, making performance highly dependent on individual core strength levels [17]. In the case of the back extension, variations in range of motion and the degree of bodyweight support across individuals hinder precise quantification of repetitions [18]. These factors likely contributed to the lack of statistical significance, suggesting the need for more refined intensity control methods for such exercises in future studies.
The results of this study show that resistance exercise effectively enhances muscular strength [19]. Furthermore, incorporating aerobic components into the training program appears to promote broader functional improvements [20]. This study provides empirical evidence that short-term, high-intensity interventions can significantly enhance maximal strength even in healthy college populations.
Nonetheless, several limitations should be acknowledged. First, the use of voluntary participants may limit the generalizability of the findings. Second, the independent effects of resistance and power training could not be fully isolated due to the sequential design of the intervention. Third, potential confounding variables such as prior training experience and physical activity levels outside the study were not controlled. Additionally, missing data were present for certain exercises and were addressed using listwise deletion.
Despite these limitations, the study presents a practical exercise program model aimed at improving maximal strength and endurance in a general college student population. The circuit-style intervention—incorporating a mix of strength- and repetition-based exercises—is suitable even for beginners and can be adapted for personalized programming based on sex and body composition.
A key strength of the study lies in its unique experimental design, which applied different training modalities to the same set of exercises. In the first phase, resistance training was conducted using the “3-second rule,” with each repetition performed over 1 minute at a controlled tempo (1.5 seconds concentric+1.5 seconds eccentric). In the second phase, the same exercises were performed for 20 seconds using a power training format aimed at maximal repetition. By distinguishing between 1RM-measurable exercises (8 types) and repetition-based exercises (4 types), the study was able to comprehensively evaluate both strength and muscular endurance. This approach enabled a clear investigation into the combined effects of movement speed, duration, and repetition count on muscle development. It also provided a basis for examining the interaction between maximal strength and muscular endurance. Such a distinction is expected to serve as a meaningful framework not only for understanding improvements in muscular strength, but also for identifying neuromuscular and metabolic responses that differ according to training modality. Ultimately, the experimental framework suggests that a hybrid training program—combining resistance and power components—may yield superior outcomes compared to using either approach in isolation.
Practical implications and recommendations
Based on the findings of this study, the following practical recommendations are proposed:
1) A combined circuit training program incorporating both resistance and power exercises is effective for improving physical fitness in university students.
2) Individualization of training variables such as intensity and repetitions is essential, taking into account sex and baseline fitness levels.
3) Technically demanding exercises (e.g., kettlebell movements) should be accompanied by proper instruction and repeated practice to ensure safety and efficacy.
4) Future studies should control for external factors such as training cycle, intensity modulation, dietary habits, and psychological motivation.
5) Longitudinal research is needed to assess the sustainability and long-term maintenance of training effects.