Mechanical, metabolic, hormonal and proteomic gender-specific differences at rest and in response to exercise/training of the muscle-tendon complex (MTC) have been identified(1). Previous studies suggest TGFβ-1(2) and IGF-I(3) exert a potent stimulus on, amongst other factors, Tendon cell proliferation, differentiation and Type I collagen synthesis. Whether a link exists between gender specific changes in MTC properties following resistance training and circulating TGFβ-1 and IGF-I levels, is unknown. Twenty-eight young participants were assigned to a training group and subdivided by gender (T males [TM] aged 20±1 year, n=8, T females [TF] aged 19±3 year, n=8), whilst 6 males and 6 females were assigned to control groups (CON). The training group completed 8 weeks of resistance training (RT) of the lower limbs. MTC properties (Vastus Lateralis, VL) pCSA and strength, patella tendon stiffness [K], Young’s modulus [E], volume [Tvol], cross-sectional area [Tcsa], and length [TL]) were assessed at baseline (week 0) and post RT (week 8) using ultrasonography, DEXA scanning, EMG & dynamometry. Circulating levels of TGFβ-1 and IGF-I were assessed at baseline and post RT using the ELISA technique. ANCOVAs, using baseline measures as covariates, were used to compare relative changes in muscle-tendon complex parameters between genders. Significant effect alpha was set at 0.05, with trends accepted at p<0.01. There were no significant differences in circulating TGFβ-1 and IGF-I levels between genders at baseline. Interestingly pooled population data showed that TGFβ-1 correlated with K at baseline (p=0.026, r=0.554). IGF-I did not correlate with any of the monitored structural or functional measures at baseline. At week 8, there was a significant increase in the mechanical and morphological properties of the muscle-tendon unit in both TM & TF, compared to CON (p<0.0001). However, there were no significant gender-specific differences (p>0.05) in changes in VL pCSA and KEMVC, or PT K, Tvol, E, IGF-I, TGFβ-1 (see Figure 1). Interestingly, there were significant (p<0.05) gender differences in ΔK at 10,20,90 & 100% MVC, with females exhibiting greater changes than males at lower force levels, and the opposite effect seen at higher force levels. The results suggest, greater resting TGFβ-1 levels may indicate superior tendon mechanical properties, whereas gender-specific resistance training-induced changes in properties do not appear to be modulated by circulating TGFβ-1. Resistance training appears to impact different areas of the PT force-elongation curve in males and females, which suggest different loading patterns may be needed to maximise resistance training adaptations in each gender, in agreement with previous work (1). The potential for TGFβ-1 to modulate tendon properties may have therapeutic importance.