Purpose <p>To investigate the effect of rifle carriage on performance, physiological responses, power output and external work during a simulated biathlon competition in the field.</p> Methods <p>Twenty well-trained biathletes (10 women) completed a simulated biathlon competition (women 3 × 1.9 km, men 3 × 2.4 km) twice, one trial while carrying the rifle (WR) and the other without rifle (NR) in a randomized counter-balanced order. Laps were separated by two simulated shootings, lasting 38.9 ± 8.2 s. Trials were separated by 30-min of active recovery. Heart rate and respiratory variables were measured throughout each trial. Furthermore, blood lactate concentration and ratings of perceived exertion were assessed after each lap. Power output and external work were estimated for both trials based on positional data. </p> Results <p>Overall roller-skiing speed was lower WR than NR (5.49 ± 0.47 vs. 5.69 ± 0.49 m∙s⁻¹, p &lt; 0.001), with largest differences during the uphill sections. No differences in physiological responses were found between WR and NR during laps or course sections (p &gt; 0.05), but oxygen uptake and breathing frequency were higher WR than NR during the second simulated shooting (p &lt; 0.05). Mean power output was slightly lower WR than NR; however, the participants performed more external work WR compared to NR due to the longer duration of the WR trial (both p &lt; 0.05). </p> Conclusion <p>Since elevated physiological markers may negatively impact standing shooting performance, biathletes should optimize their pacing strategies to maximize overall performance. In addition, rifle carriage increases external work through a lengthened skiing duration, which should be considered when planning and performing biathlon training.</p>