This study examined the effects of core and muscle temperature on force steadiness and motor unit discharge rate (MUDR) variability after a hot-water immersion session. Fifteen participants (6 women; 25±6 years) completed neuromuscular assessments before and after either 42ºC (hot) or 36ºC (control) water immersion. Force steadiness was measured during knee extension, while HD-sEMG signals were recorded from vastus lateralis and medialis for MUDR variability analysis. Following water immersion, force steadiness decreased by 0.11% (p<0.05; d=0.38) and MUDR variability increased by 1.25% (p<0.01; d=0.57) potentially driven by increased muscle temperature. Elevated core temperature did not further affected these changes.