The present study examined whether different pre-information conditions could lead to a volitional modulation of the occurrence and magnitude of the bilateral force deficit (BFD) during isometric leg press. Twenty trained male adults (age: 24.5 ± 1.7 years; weight: 77.5 ± 7.1 kg; height: 1.81 ± 0.05 m) were examined on three days within a week. Isometric leg press was performed on a negatively inclined leg press slide. Each participant completed three maximal isometric strength test sessions with different pre-information conditions given in a graphical chart: no pre-information (NPI; first day), false pre-information (FPI; bilateral force > sum of unilateral forces; second or third day) and correct pre-information (CPI; bilateral force < sum of unilateral forces; second or third day) during bilateral, unilateral-left and unilateral-right leg-press. The sum of left- and right-sided force values were calculated for bilateral (F_BL = F_{BL_left} + F_{BL_right}) and unilateral (F_UL = F_{UL_left} + F_{UL_right}) analyses. Force data for NPI revealed: Mean (SD): F_{UL_NPI} = 3023 N (435) vs. F_{BL_NPI} = 2812 (453); FPI showed F_{UL_FPI} = 3013 N (459) vs. F_{BL_FPI} = 2843 (446) and the CPI revealed F_{UL_CPI} = 3035 (425) vs. F_{BL_CPI} = 2844 (385). The three (no, false, correct) x 2 (F_UL, F_BL) rANOVA revealed a high significant main effect of Force (F = 61.82, p < 0.001). No significant main effect of the factor Condition and no significant interaction between Force x Condition was observed. The BFD does not rely on the trueness of the given pre-information (no, false, correct). Cognition-based volitional influences on the BFD on supra-spinal level seem negligible.

• BFD is reliable occurring phenomenon

• Available theoretical knowledge does not affect the BFD

• Alternating sport should include alternating strength exercises