The energy cost of internal work and its relationships with lower limb mass and pedalling frequency were studied in four male subjects [age 22.2 (SD 1.5) years, body mass 81.0 (SD 5.1) kg, maximal O2 uptake (VO2max) above resting 3.06 (SD 0.4) l.min-1]. The subjects cycled at 40, 60, 80 and 100 rpm and at five different exercise intensities for every pedalling frequency (unloaded condition, UL); the same exercises were repeated after having increased the lower limbs' masses by 40\% (loaded condition, L). The exercise intensities were chosen so that the oxygen consumption (VO2) did not exceed 75\% of VO2max. For all the subjects and all the conditions, the rate of VO2 above resting increased linearly with the mechanical power (W). The y-intercepts of the linear regressions of VO2 on W, normalised per kilogram of overall lower limbs mass were the same in both UL and L and increased with the 4.165 power of pedalling frequency (fp). These intercepts were taken to represent the metabolic counterpart of the internal power dissipation in cycling; they amounted to 0.78, 0.34, 3.29 and 10.30 W.kg-1 for pedalling frequencies of 40, 60, 80 and 100 rpm respectively. The slope of the regression lines (delta W/delta VO2) represents the delta efficiency of cycle ergometer exercise; this was also affected by fp, ranging, on average, from 22.9\% to 32.0\%. These data allowed us to obtain a comprehensive description of the effects of fp (per minute), exercise intensity (W, watts) and lower limbs' mass with or without added loads (mL, kg), on VO2 (ml.min-1) during cycling: VO2 = [mL.(4.3.10(-8).fp4.165/0.35)] + (1/[(3.594.10(-5).fp2 - 0.003.fp + 0.326).0.35]).W. The mean percentage error between the VO2 predicted from this equation and the actual value was 12.6\%. This equation showed that the fraction of the overall VO2 due to internal work, for a normal 70-kg subject pedalling at 60 rpm and 100 W was of the order of 0.2.
Oxygen cost of internal work during cycling / M. P., Francescato; Girardis, Massimo; P. E., Di. - In: EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY. - ISSN 0301-5548. - STAMPA. - 72(1995), pp. 51-57.
|Data di pubblicazione:||1995|
|Titolo:||Oxygen cost of internal work during cycling.|
|Autore/i:||M. P., Francescato; Girardis, Massimo; P. E., Di|
|Codice identificativo ISI:||WOS:A1995TL53600009|
|Codice identificativo Scopus:||2-s2.0-0029589335|
|Codice identificativo Pubmed:||8789570|
|Citazione:||Oxygen cost of internal work during cycling / M. P., Francescato; Girardis, Massimo; P. E., Di. - In: EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY. - ISSN 0301-5548. - STAMPA. - 72(1995), pp. 51-57.|
|Tipologia||Articolo su rivista|
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