## 4 Discussion  
This study analyzed the effects of LI-HR and HI-LR resistance exercises in older adults over a 12-week intervention period, which focused on functional fitness, myokine levels, and muscle adaptations. The average attendance rate of participants was 92%, with no injuries or adverse events being observed. RT involved 10-25 reps per session, which is consistent with findings reported by [PERSON] [24], who showed that combining machine and free weights (15 reps) reduced body and abdominal fat in older adults over a 12-week intervention period. A higher training volume may enhance fat reduction given that RT increases energy expenditure through post-exercise oxygen consumption [25]. However, sedentary individuals may counteract this by increasing energy intake [26]; accordingly, further research is warranted to elucidate the effect of RT on total energy expenditure. Nonetheless, combined exercises are more effective in reducing body fat than single-exercise approaches (e.g., aerobic or resistance training) [27]. Regarding functional physical fitness, the HI-LR group showed greater improvements in muscle strength (e.g., STS test), which can reduce the risk of falling and enhance exercise performance. Contrastingly, the LI-HR group showed significant improvements in dynamic balance and gait speed (e.g., TUG test), which facilitate daily tasks requiring sustained effort. This is consistent with the specificity of the exercise regimens since HI-LR targets fast-twitch  
Figure 2: Difference in myokines between groups and time by generalized estimating equation (GEE) model. Difference and changes of IL-6 (**a**), IGF-1 (**b**), SPARC (**c**), BDNF (**d**). * **, ***  
fibers for power, while LI-HR focuses on slow-twitch fibers for endurance. Furthermore, we assessed the isometric strength of the ankle and relative muscle power using the STS test. The results showed the main effects of dorsiflexion strength and STSpower over time in the LI-HR and HI-LR groups, with a tendency to increase in Post (dorsi flexion: 8.9%, 10.6%; STSpower: 17.6%, 11.1%). This is consistent with the clinically relevant thresholds of 0.33 and 0.42 W/kg-1 for women and men, respectively, suggested by [PERSON] et al. [28]. [PERSON] et al. [29] argued that to improve frailty and physical function in older adults, high-intensity RT should be included, if possible. High-intensity exercises are very effective in improving strength and power in a short period of time; however, it carries a higher risk of injury, especially to joints and connective tissue that may already be compromised by age-related degenerative changes. It may even have the negative effect of reducing strength. In this study, the LI-HR and HI-LR groups showed similar functional improvements. LI-HR training is generally safer because it places less mechanical stress on the body and provides significant benefits in endurance, functional fitness, and health. Therefore, a balanced approach combines LI-HR and HI-LR to minimize injury risk while providing physiological benefits such as increased muscle mass and strength, improved endurance, and neuroplasticity may be the most effective strategy. In older adults, RT can help regulate the levels of myokines such as IL-6, IGF-1, SPARC, and BDNF, which promote muscle growth, regeneration, anti-inflammation effects, and neuroplasticity. In the present study, both experimental groups showed a significant decrease in IL-6 levels, suggesting that RT plays a role in reducing chronic inflammation. Elevated IL-6 is associated with extreme fatigue, rapid weight loss, and sarcopenia in the elderly. IL-6 and tumor necrotic factor-\(\alpha\) activate the Janus kinase signal transducer and activator of transcription pathway, which is associated with inflammation, cancer development, and muscle mass atrophy [30]. IL-6 also blocks myocyte development, causing microstructural myofibrillar degradation and replacing muscle mass with collagen and fat [30].