Comparing six weeks of full-body eccentric quasi-isometric and dynamic resistance training on muscular size, physical performance, and serum hormones in untrained men

Eccentric quasi-isometrics (EQI) have gained popularity as a potential means of promoting muscular adaptations when traditional resistance training is contraindicated. However, evidence regarding their chronic effects remains limited. Thirty untrained men (18–26 years) were randomized to full-body EQI (n = 10), dynamic resistance training (DYN; n = 10), or a non-training control group (CON; n = 10). Muscle size, strength, power, endurance, and serum hormone concentrations were assessed before and after the six-week (three sessions/week) intervention. Within-group changes were assessed using paired-samples Wilcoxon signed-rank tests, while between-group differences were analyzed using ANCOVA with baseline value covariates. Changes in all dependent variables were similar between EQI ( d = 0.23–3.03, Wilcoxon p ≤ 0.069) and DYN ( d = 0.22–4.33, Wilcoxon p ≤ 0.105), with both training groups improving more than CON ( d = -0.79–0.14, Wilcoxon p ≥ 0.103). However, no significant between-training-group differences were detected ( Bonferroni p = 0.400–1.00), though EQI tended to

Result: in small-to-moderately greater beneficial changes in upper-body strength and endurance, and growth hormone and follistatin ( d = 0.35–0.70). In contrast, muscle size, lower-body strength and endurance, jump power, and cortisol concentrations improved by a greater magnitude following DYN ( d = 0.24–0.70). Both training groups generally improved more than CON. These

Findings: suggest that six weeks of EQI training elicits beneficial morphological, neuromuscular, and endocrine adaptations comparable to traditional dynamic resistance training in untrained young men.