In adolescent female athletes, monitoring physical condition using non-invasive methods such as urine could speed the provision of information to athletes and coaches, thereby preventing injuries and promoting improved performance. On this matter, it has been reported that physical stress is cumulatively increased by prolonged training in adolescent female athletes. Given the potential to monitor the cumulative effects of long-term training at the level of renal function, this could provide appropriate feedback to adolescent female athletes regarding their physical condition. Accordingly, the purpose of this study was to clarify the accumulative effects of long-term volleyball training on renal damage, based on urinary liver-type fatty acid-binding protein (L-FABP), in adolescent female athletes. Twenty-one eumenorrhoeic female volleyball players (as baseline values; age: 16.4±0.8 years, height: 161.9±5.8 cm, body mass: 55.6±5.7 kg, BMI: 21.8±1.2 kg/m2, body fat: 24.5±3.0 % [mean±SD]) participated in this study. All athletes carried out volleyball training in the school gym, which consisted of ball handling, specialized drills, and practical game-style exercises, including physical (aerobic/anaerobic) training. The training cycle was six days per week, with approximately 2 to 2.5 hours of volleyball training per day. In order to determine the cumulative effects of tubular injury (urinary L-FABP), urine samples were collected before and after volleyball club activities on three successive days (Days 1, 3, and 5) at 0 (baseline) and 10 months (two consecutive summer seasons), respectively, for the later analysis of urinary L-FABP using chemiluminescent enzyme immunoassay. Student's T-test was performed on the analyzed data of urine samples collected prior to the club activity, using values calculated as the mean of three consecutive days. No significant difference was observed in urinary L-FABP after 10 months of volleyball training (μg/g creatinine; 1.39±1.6 for 0 month, 1.17±0.8 for 10 months, respectively). The results of this study may partially explain the possibility that training adaptation occurred or that a threshold to overtraining was not reached after one year of training. Since physiological and environmental factors such as heat stress are presumed to be intricately involved in long-term training in a non-air-conditioned indoor environment, the biomarkers used in this experiment may be important dependent variables in monitoring overtraining of female indoor athletes. Supported partly by funds from Wesco Scientific Promotion Foundation (2022-71 to N. Y.) in Japan. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.