Optimizing Gym Performance: Evaluating the Impact of Nutritional Supplementation on Strength and Endurance in Recreational Gym-Goers

This study examines the effects of nutritional supplementation (NS) and resistance training on strength performance across different gender and age groups over 8 weeks. A total of 218 participants were categorized based on NS intake: L-carnitine (LcS), creatine (CS), proteins (PS), a combination of protein, creatine, and L-carnitine (PCLcS), and a non-supplemented control group (NNS). Strength performance was assessed through 1RM (one repetition maximum) tests in back squats, bench presses, deadlifts, biceps curls, triceps extensions, and pull-ups. All participants exhibited pro-gressive strength improvements, with PCLcS consumers achieving the most significant gains across all exercises (e.g., a 15.8% increase in 1RM back squat), followed by LcS (11.3%). CS and PS user (U) groups showed moderate improvements, while NNSUs recorded the lowest performance increases (5.7%). Despite these differences, statistical significance was not reached (p >0.05), suggesting that factors such as training history, genetic predisposition, and recovery strategies may influence strength adaptations. Gender-related differences were evident, with men consistently outperforming women across all exercises (20–35% higher 1RM values), likely due to physiological factors such as greater muscle mass and testosterone levels. However, both genders showed comparable relative improvements over time (men: +13.4%, women: +12.6%). Age-related trends revealed a gradual decline in performance, with the 40-49 age group displaying the lowest strength levels, particularly in the 1RM back squat (9.2% lower than the 20-29 group). However, older participants still exhibited meaningful strength gains (+9.1% over 8 weeks), reinforcing the importance of resistance training in mitigating age-related muscle decline. These findings suggest that NSs, particularly PCLcS, may enhance strength performance when combined with structured resistance training.