PhD A.I. Golovachev¹
Dr.Biol., PhD B.A. Dyshko²
PhD S.V. Shirokova^3
1All-Russian Scientific Research Institute of Physical Culture and Sports, Moscow
²LLC "Sport Technology" Sports Engineering Association, Moscow
³Moscow Secondary Special School of Olympic Reserve No. 2 Moscow City Department for the Physical Culture and Sport, Moscow

The study analyzes the age-specific maximal lung ventilation (MLV) and oxygen consumption (OC) indices identified by the exhale volume and content (oxygen to carbon dioxide ratios), respectively; that are indicative of the muscular work intensity. Sampled for the study were 11-28 year-old male cross-country skiers (n= 696) with sport records of 3-20 years, with the skills ranging from the beginner level to the World Class Master of Sport. The sample was tested by Quinton (US-made) submaximal treadmill exercise, with the run speed varying from 2.0 m/s (7.2 km/h) to 3.0 m/s (10.8 km/h) depending on the age and skill level; with the treadmill floor fixed at 1º; and the speed stepped up by 0.5 m/s (1.8 km/h) every 3 min.
The study data and analyses showed that progress of the external respiration functionality is most intensive in the periods of 11-12 and 19-22 years of age, as verified by the definitive maximal lung ventilation and oxygen consumption indices, with the peak levels reached by 25-28 years of age. The age-specific variations of the functionality rates are interpreted as due to a variety of endogenous and exogenous factors of the external respiratory function onthogenesis and competitive loads, with the leading role of the endurance progress indices.

Keywords: sport onthogenesis, age-specific variations, growth process rate, external respiration rates, maximal lung ventilation, oxygen consumption index, cross-country skiers.

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