Editorial

Gas exchange measurements during exercise have been conducted for many decades. They have served as major tools of performance assessment in both healthy and diseased subjects. During the 1970s and early 1980s, the invention and refinement of “lactate diagnostics” led to diminished scientific interest in exercise gas exchange measurements. However, more recent methodological developments have renewed study options. This is shown by the growing number of original articles published in this area. Therefore, it is timely to summarize these new thoughts within a supplement issue of the International Journal of Sports Medicine. This supplement gives equal attention to more basic methodological topics (first part of the supplement: Atkinson et al., Röcker et al., Meyer et al.) and to applied ones (second part: Jeukendrup et al., Meyer et al., Myers).

Within the first part, Atkinson et al. start by reviewing inherent (still relevant) methodological difficulties of gas exchange measurements during exercise with emphasis on the necessity of appropriately addressing reliability issues. Then Röcker et al. explain options and limitations of high-frequency measurements (breath-by-breath and even intra-breath analysis). It is noteworthy to recognize that high temporal resolution does not represent the panacea of gas exchange measurements during exercise because it also poses a number of problems. Apart from increasing the temporal resolution of measurements, the step to ambulatory conduction represents the second recent advancement in gas exchange measurements. Therefore, Meyer et al. review the methodology and current applications of this method and discuss promising areas of research.

Besides performance assessment, indirect calorimetry is probably the second most frequent application of gas exchange measurements during exercise. The obesity epidemic as well as related dyslipidemia in Western countries have stimulated interest in so-called “fat metabolism training.” This issue has been thoroughly investigated by the working group of Jeukendrup et al. who contribute a review of this field. Furthermore, for endurance training, a maximization of fat metabolism capacity is a frequently held target of athletes, which makes a discussion of Jeukendrup's “fat max” concept worthwhile from both basic and applied aspects. A more general model for performance assessment and exercise prescription by means of gas exchange measurements during exercise is presented by Meyer et al. who discuss its validity for unfit subjects - even in disease -, as well as for highly trained individuals. It disregards maximal ergometric measurements and involves the use of two submaximal indices only. The transfer of this “submaximal approach” to cardiac and pulmonary rehabilitation is part of Myers' article at the end of this supplement. It covers recent trends in the use of gas exchange parameters during exercise. These were most often derived from investigations in patients with chronic heart failure and give insight into disease severity, the necessity of invasive measures, and prognosis.

The guest editor of this issue hopes that the contents of this supplement are helpful for practice as well as scientific purposes and provide evidence for a reasonable and justifiable use of gas exchange measurement options during exercise in the future. Many thanks to all authors and the reviewers who contributed substantially to improving the quality of all papers.