Introduction Firefighters’ (FFs) cardiorespiratory fitness is considered an important capacity for workability. To successfully complete safety standards and rescue protocols, FFs are required to accomplish minimum values of relative VO2max. Physical fitness programs for FFs must take into consideration physiological demands, being essential not only for professional tasks but also as a guarantee of their personal safety. This research aimed to investigate the influence of specific functional training (FT) with and without personal protective equipment (PPE) and self-contained breathing apparatus (SCBA) on the FFs’ cardiorespiratory fitness. Material and methods Sixty FFs were randomly allocated in three groups (EG1 training with PPE+SCBA; EG2 training with regular fitness equipment and the control group) and enrolled for a 24-week (two sessions/week) FT intervention program. FFs were assessed in anthropometric and 12-minute Cooper test, pre and post-intervention. Results Both training groups demonstrated significant improvements from baseline to post intervention EG1 VO2max (39.8 ± 6.5ml.kg−1.min−1 and 41.2 ± 5.6ml.kg−1.min−1, p < 0.001, +3.5%; EG2 VO2max 41.5 ± 8.3ml.kg−1.min−1 and 42.5 ± 7.5ml.kg−1.min−1, p < 0.05, +2.4%). Conclusions The proposed FT intervention, considering the provided equipment in all fire departments, and even without running tasks, seems to be adequate for developing FFs’ VO2max. Regular FT with PPE+SCAB must be encouraged to improve adequate VO2max and fitness levels related to firefighting specific tasks.

Objective: To investigate the influence of specific functional training (FT) with and without personal protective equipment (PPE) and self-contained breathing apparatus (SCBA), on firefighters (FFs) physical fitness condition. Methods: Sixty FFs run a 24 weeks intervention, divided into three groups (EG1 training with PPE+SCBA; EG2 training with regular equipment, and Control Group). FFs anthropometric and physical fitness (PF) were assessed pre- and post-intervention. Results: Significant differences were found between the training groups and control group. Both training groups interventions were effective in improving PF and lean mass. However, EG1 presented a higher percentage of improvement. Conclusion: This 24-week FT intervention improved participants’ muscle strength, endurance, and power, and it led to increases in lean body mass. Regularly FT with PPE+SCBA helps FFs maintain a healthy general physical condition and develop optimum fitness levels related to firefighting specific tasks, specially torso muscular endurance.