Energy cost of scuba underwater breathing apparatus on ventilation

abstract Self-contained underwater breathing apparatus (SCUBA) enables underwater work by allowing users to breathe in that environment, but it also increases mechanical load and limit's respiratory function. To assess the energy cost of breathing through SCUBA, we measured resting oxygen consumption with and without a regulator in three groups: junior divers (n=22), adult divers (n=10), and non-diving adults (n=10). Oxygen consumption rose from 241.3 to 414.8 mL O2/min, increasing energy expenditure from 4.8 to 8.3 kJ (? = 3.65 kJ). Breathing with the regulator required significantly more oxygen than breathing without it (paired t-test, p = 0.0246), and this effect was consistent across all three study groups. These changes were also associated with higher VCO2 (6.89 vs. 9.21 L/min; p < 0.0001), tidal volume, and minute ventilation (6.89 vs. 9.20 L/min; ? = 2.31 L/min; p < 0.0001). SCUBA-related mechanical constraints significantly increase breathing effort and alter ventilatory parameters. These effects were similar in children aged 7-13 years and adults, regardless of diving experience. Because the regulator adds mechanical respiratory load and is classified as Class III personal protective equipment, it must comply with manufacturing and maintenance requirements set by diving equipment regulations and standards in many countries.