Can breathing gases be analyzed without a mouth mask? Proof-of-concept and concurrent validity of a newly developed design with a mask-less headset

A portable headset has been developed to analyze breathing gases and establish the energetic workload of physically active workers. This proof-of-concept study aimed to investigate the following: (1) the validity of the headset compared to indirect calorimetry using a mouth mask; (2) the validity of the headset compared to the validity of oxygen consumption (VO2) estimated on the basis of heart rate; (3) the influence of wind on validity; and (4) user experiences of the headset. Fifteen subjects performed a submaximal cycling test twice, once with the headset, and once with a mouth mask and heartrate monitor. Concurrent validity of the headset was analyzed using an intraclass correlation coefficient (ICC). Across all phases, a good correlation between the headset and mouth mask was observed for VO2, carbon dioxide production (VCO2) and exhaled volume (VE) (ICC >= 0.72). The headset tended to underestimate VO2, VCO2 and VE at low intensities and to overestimate it at higher intensities. The headset was more valid for estimating VO2 (ICC = 0.39) than estimates based on heart rate (ICC = 0.11) (n = 7). Wind flow caused an overestimation (md >= 18.4 +/- 16.9%) and lowered the correlation of VO2 between the headset and the mouth mask to a moderate level (ICC = 0.48). The subjects preferred the headset over the mouth mask because it was more comfortable, did not hinder communication and had lower breathing resistance. The headset appears to be useable for monitoring development of the energetic workloads of physically active workers, being more valid than heart rate monitoring and more practical than indirect calorimetry with a mouth mask. Proof-of-concept was confirmed. Another design step and further validation studies are needed before implementation in the workplace.