Background: With the increasing popularity of fitness, there is a growing need for novel mechanisms to evaluate the compliance of load parameters with adaptive body reserves. This study aims to evaluate the correlation between load volume and adaptive compensatory body responses among untrained young individuals undergoing various power fitness regimens. Material and methods: The study comprised 60 young men, aged 17±0.4 years, with no prior fitness experience. They were divided into two groups and subjected to the most prevalent load modes in power fitness (R_a =0.53 and R_a =0.72) for a duration of 12 weeks. Methods of bioimpedancemetry, anthropometry, testing of maximum strength development (1 PM), and biochemical blood tests (creatinine, cortisol, testosterone) were used to analyze adaptative compensatory reactions to physical stimulus. The correlation between load volume parameters (Wn) and controlled indicators of adaptive body changes was determined using Spearman's rank correlation coefficient. Results: In the study, Wn varied depending on the load mode characteristics. The initial parameters of maximum strength development were almost identical in all study participants. The load volume parameters were 61.9% higher in group 1. During the research, the maximum strength development increased by 20.9% in group 2 representatives. The studied morphometrical indicators expressed the highest adaptative changes in group 2. The biochemical blood markers provided different manifestations of adaptative compensatory reactions of study participants depending on load modes. An increase in the basal creatinine level, indicating muscle mass growth, was found only in young men of group 2. A significant increase in blood cortisol, which demonstrates compensatory reactions, was observed during all stages of the study in participants of group 1. A strong correlation between the load volume and 1 PM, FFM, and BCM indicators was observed in both groups. An inverse moderate to strong correlation between Wn and basal testosterone level was found in both groups during the observation period. The absence of correlation between Wn values, circumferential body measurements, and fat mass in young men of group 1 is justified by the peculiarity of the load mode. Conclusions: Using a low-volume load mode (R_a =0.72) by untrained young men contributed to the most accelerated adaptive body changes during fitness training. The obtained correlation allows for ascertaining a distinct correlation between the external stimulus magnitude and adaptive body change formation. The determination of strong correlations between the studied indicators in different load modes will contribute to the improvement of the training system in fitness.