For Cardiorespiratory Fitness, Measure Lean Body Mass Rather Than Total Weight Interview with:
Tuomo Tompuri, MD
Clinical Physiology and Nuclear Medicine
Kuopio University Hospital, Finland

Medical Research: What are the main findings of the study?

Dr. Tompuri: Measures of the cardiorespiratory fitness should be scaled by lean mass instead of body weight, while aiming to enable comparison between the subjects. Our result is physiologically logical and confirms earlier observations of the topic. Scaling by body weight has been criticized, because body fat, per se, does not increase metabolism during exercise. We did observe that scaling by body weight introduces confounding by adiposity.

Medical Research: What was most surprising about the results?

Dr. Tompuri: While using by body weight scaled measures of the cardiorespiratory fitness, fat mass was even stronger determinant of the weight proportional measures as compared to actual performance in the exercise test.

Medical Research: What should clinicians and patients take away from your report?

Dr. Tompuri: Cardiorespiratory fitness refers physiologically to an individual’s aerobic and energy metabolic capacity. On other hand, exercise performance is influenced also by body weight which must be carried during locomotion and exercise performance. Thus, exercise performance reflects functional capacity, while cardiorespiratory fitness represents more specific physiological response. Body weight proportional measures are indicators of the functional capacity and refer to composite indicator of the health risk by adiposity and poor cardiorespiratory fitness. However, adiposity and cardiorespiratory fitness are independent determinants of the health. While measuring cardiorespiratory fitness, lean mass proportional measures should be used, because lean mass proportional measures are physiologically more specific for energy metabolic response as compared to weight proportional measures.

What recommendations do you have for future research as a result of this study?

Dr. Tompuri: In general references for lean mass proportional measures of the cardiorespiratory fitness should be published in all age groups. Age related decrease in weight proportional measures of the cardiorespiratory fitness is strongly explained by decrease in lean mass content during aging. Prognostic or diagnostic value of the clinical exercise testing may potentially improve while using lean mass proportional measures of the cardiorespiratory fitness. Potential significance of the more specific scaling should be evaluated for example among patients of the pre-operative assessment. Moreover, health related interactions of the cardiorespiratory fitness and adiposity should be studied more among “fat but fit”, “lean but unfit”, “lean and fit” and “fat and unfit” using lean mass proportional definition for cardiorespiratory fitness.


Measures of cardiorespiratory fitness in relation to measures of body size and composition among children
Tompuri T1, Lintu N, Savonen K, Laitinen T, Laaksonen D, Jääskeläinen J, Lakka TA.
Clin Physiol Funct Imaging. 2014 Aug 27. doi: 10.1111/cpf.12185. [Epub ahead of print]