Background: Army operations produce various psychophysiological responses of military personnel. Traditionally, to prepare soldiers for these requirements, military workouts have been based on long-distance and low-intensity training. Recent researches suggest that high-intensity interval training (HIIT) may be more effective due to the characteristics of actual theaters of operation. there is a lack of research on the actual effects of military equipment in the context of combat or HIIT training. This study aimed to analyze the effects of military equipment on psychophysiological responses during a HIIT session. Methods: 20 soldiers of the Spanish Army (aged 27.3 ± 3.4 years; height 176.6 ± 4.7 m; weight 76.8 ± 7.4 kg) were evaluated after and before a traditional running HIIT which consisted of 12 repetitions of 30 seconds at maximum intensity, with a 30-second rest between exercises. Blood lactate, rate of perceived exertion and stress, upper and lower limbs, and respiratory muscle strength, skin temperature, blood oxygen saturation, heart rate, cortical arousal were measured before and after the training. Results: Results are reported with their mean and standard deviation. Significant differences were found in RPE, SSP, BOS, and Lactate in both groups in pre and post-training with the two outfits analyzed. Also, it was observed significant differences in HJ, UMS, and PEF values when the group was equipped with military equipment. Significant differences were found in RPE pre-training values and RPE, Stress perception, BOS, HR, and lactate post-training values. Conclusions: The use of military equipment during a high intensity interval training session produces higher stress perception and perceived exertion than the civil outfit. The mechanical difficulty and the lack of operability in movements could be a reason for this psychophysiological response.