Background: Obesity is a growing public health issue, increasing the risk of metabolic disorders and cardiovascular diseases. Physical activity is a key factor in obesity treatment; however, the effectiveness of different exercise modalities remains unclear, especially considering age-related physiological differences. High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) are two commonly recommended strategies, but their impact on fat reduction across different age groups has not been thoroughly analyzed. This study aims to determine which training modality is most effective for fat reduction in individuals with obesity, considering age as a crucial factor in exercise response. Methods: A systematic review was conducted, analyzing studies published between 2014 and 2024. The inclusion criteria focused on the studies comparing HIIT and MICT effects on body composition in obese individuals of different age groups. The data extraction included training protocols, fat mass reduction, and adherence levels. The primary outcomes measured changes in body fat percentage and muscle mass retention. Results: HIIT was found to be most effective for younger individuals (18–30 years), promoting fat oxidation and muscle retention. In middle-aged adults (31–40 years), both HIIT and MICT yielded similar benefits, with MICT preferred due to better adherence. In older adults (41–60 years), MICT provided a more sustainable strategy for fat reduction and muscle preservation. However, the variability across the studies limits definitive conclusions. Conclusions: Age influences the effectiveness of HIIT and MICT for obesity treatment, highlighting the need for age-specific exercise recommendations. Future studies should standardize training protocols and assess long-term metabolic adaptations to optimize physical activity guidelines.

Background/Objectives:Training periodization is fundamental to optimizing athletic performance, with carbohydrate metabolism playing a critical role in supporting high-intensity efforts by facilitating muscle glycogen resynthesis. Recent studies suggest that high carbohydrate diets and high molecular weight carbohydrate (HMWC) supplementation can improve both endurance and anaerobic performance, while potentially influencing oxidative stress. This study investigates the effects of a high carbohydrate diet combined with HMWC supplementation on anaerobic performance and oxidative stress markers in elite swimmers. Methods: Eight national-level swimmers (tier 3–4) completed a three-day training microcycle with dietary interventions. Anaerobic capacity was assessed using Wingate tests for upper and lower limbs, while swimming performance was evaluated through an 8 × 100 m exercise protocol. The study was conducted using a one group quasi-experimental design with a pre-test/post-test structure, with participants acting as their own controls. Baseline measurements were taken prior to the intervention, followed by the administration of the high carbohydrate diet and HMWC supplementation. Post-intervention assessments were performed using the same test protocols to assess changes in performance and oxidative stress markers (such as GSH, CK, MDA, FRAP), which were determined by ELISA. The samples were stored at −80 °C until the evaluations. STATISTICA 5.0 (StatSoft, Inc., 1995) was used for statistical analysis of the obtained results. Results: The obtained results demonstrated significant improvements in peak power output for the lower limbs following supplementation (p < 0.001) and a reduced time to peak power for the upper limbs (p < 0.001). Additionally, velocity during the final swimming segments increased significantly following the intervention (p < 0.001). However, no notable changes were observed in antioxidant enzyme activity (SOD, CAT, GPx, GR) or low molecular weight antioxidants, suggesting a potential ceiling effect in redox adaptations. Lipid peroxidation, measured by MDA levels, increased post-supplementation (p < 0.05), indicating oxidative stress associated with high-intensity training and supplementation. Conclusions: The findings underscore the efficacy of combined dietary strategies with HMWC in enhancing anaerobic performance in swimming, while highlighting the necessity for further exploration of oxidative stress dynamics.