Multidimensional Physiologic Adaptations to a 14-Day Detraining Period in Elite Powerlifters: Neuromuscular, Morphological, and Hormonal Responses

ABSTRACT: Yılmaz, U, Buzdağlı, Y, Bilgin, S, Sepil, Y, Ozan, M, Bağaçlı, UH, Şıktar, E, Baygutalp, F, and Kılıç Baygutalp, N. Multidimensional physiologic adaptations to a 14-day detraining period in elite powerlifters: Neuromuscular, morphological, and hormonal responses. J Strength Cond Res 40(9): 1085-1094, 2026-Short-term detraining has been associated with alterations in neuromuscular performance and hormonal regulation; however, its combined effects on neural activation, muscle morphology, and endocrine responses in elite strength athletes remain incompletely characterized. The purpose of this study was to examine the effects of a 14-day detraining period on neuromuscular performance, electromyographic activity, muscle morphology, and hormonal-biochemical responses in elite male powerlifters. Twenty trained powerlifters completed all assessments before and after the detraining period. Neuromuscular performance was evaluated using the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), and a 20 m sprint test. Surface electromyography was used to quantify muscle activation parameters, including root mean square (RMS) amplitude, median frequency, and antagonist coactivation. Muscle morphology was assessed by ultrasonography, while serum creatine kinase (CK), lactate dehydrogenase, interleukin-6 (IL-6), cortisol, testosterone, and the testosterone-to-cortisol (T/C) ratio were analyzed to characterize biochemical and hormonal responses. After detraining, several neuromuscular performance variables demonstrated statistically significant declines, including CMJ reactive strength index, IMTP rate of force development, and sprint performance. These changes were accompanied by alterations in electromyographic activation patterns, characterized by reduced quadriceps RMS amplitude and increased hamstring coactivation. In contrast, changes in muscle thickness and cross-sectional area did not reach statistical significance, although a small increase in muscle echo intensity was observed. Biochemically, CK and IL-6 concentrations increased, cortisol levels rose, testosterone declined, and the T/C ratio decreased, indicating a transient shift in endocrine balance. In conclusion, a 14-day detraining period was associated with measurable changes in neuromuscular performance, electromyographic activation, and hormonal-biochemical markers in elite powerlifters, while structural muscle adaptations remained inconclusive. Although the findings suggest that early detraining-related performance impairments may be more closely related to functional and regulatory adaptations than to clearly detectable morphologic changes, this interpretation should be considered tentative within the limitations of the study design and statistical framework.