Supramaximal Exercise

Abstract

Powers higher than the maximal aerobic power can be attained relying on anaerobic lactic and alactic metabolisms as energy source. These metabolisms are analysed separately in this Chapter, where the power and capacity of both have been quantified. Anaerobic lactic metabolism has been treated first, although it is still a controversial issue on quantitative grounds, because several authors denied the possibility of performing a correct estimate of the metabolic energy corresponding to a mole of lactate accumulation in blood. Thus, its analysis is preceded by a preliminary discussion of the principles and assumption behind the concept of energetic meaning of blood lactate accumulation is based. Then, anaerobic alactic metabolism is discussed, for which a distinction between average and instantaneous powers is introduced: the former reflects the rate of ATP resynthesis from the Lohmann's reaction and the latter refers to the maximal rate of ATP hydrolysis and concerns the ATP already available at the contraction site. This analysis shows that the maximal power generated by anaerobic alactic metabolism is extremely high, up to some 20 times higher than the maximal aerobic power for the instantaneous methods. The price to pay for this is an extremely low capacity, so that exercise can be sustained at maximal power only for a very short time, of the order of a few seconds for average power, some milliseconds for instantaneous power. Such an organization of energetic metabolism, with a wide range of powers and capacities for the ensemble of the metabolic pathways, allows animals, humans included, to face the multiple needs that a prey-predator system imposes. In general terms, animals have evolved in such a way that power is highest when capacity is lowest, and vice versa.

Energetics of sinusoidal exercise below and across critical power and the effects of fatigue

“…In CP ex , other factors may have contributed to the increase in , , and MP in addition to the mechanisms discussed here above. Indeed, the growth of the cardiorespiratory and metabolic response could also be an effect of the slow component of , which is known to occur above the CP and which is mainly related to the recruitment of fast-twitch fibers and to a progressive shift toward fatty acid utilization during a long-lasting exercise (Jones et al 2011 ; Ferretti 2015 ; Burnley and Jones 2018 ). The higher [La − ] observed in our study in CP ex seems to support this statement.…”

“…4 ), even though T was the same. Since, in absence of [La − ] accumulation during an exercise transient, the time constant of the kinetics is invariant, power independent, and equal to that of phosphocreatine breakdown (di Prampero and Margaria 1968 ; Binzoni et al 1997 ), and since the mechanical AMP was the same in CP ex as in CP-50 ex , the postulated higher oxygen deficit in the former than in the latter case can only be attributed to its anaerobic lactic component (facultative component of the oxygen deficit due to early lactate accumulation) (di Prampero 1981 ; Ferretti 2015 ).…”

“…The history of the energetics of muscular exercise concerns mostly the study of the cardiorespiratory and metabolic responses to square-wave, constant-power submaximal work (di Prampero 1981 ; Whipp and Ward 1982 ; Poole and Jones 2012 ; Ferretti 2015 ; Ferretti et al 2022 ). In a square-wave transition from rest to light or moderate exercise, during which no lactate accumulation occurs, the time constant of the primary component of the bi-exponential pulmonary oxygen uptake ( ) kinetics (Poole and Jones 2012 ; Ferretti 2015 ) corresponds to that of phosphocreatine breakdown (Binzoni et al 1992 ; Rossiter et al 2002 ). In this type of exercise, the rest-to-exercise transition (on-phase) and exercise-to-rest transition upon exercise cessation (off-phase) show a symmetrical response (Özyener et al 2001 ).…”

“…Due to anaerobic metabolism contribution to energy supply in this transient, asymmetries between the two phases appear, with a longer time constant in the on- than in the off-phase (Paterson and Whipp 1991 ; Özyener et al 2001 ). In this scenario, the appearance of the so-called slow component, accompanied by a continuous increase in blood lactate accumulation, carries along a furtherly accentuated asymmetric pattern between the on- and off-phases of the kinetics (Poole et al 1994 ; Jones et al 2011 ; Ferretti 2015 ).…”

Effects of Water Immersion on the Internal Power of Cycling

“…Second, because we relied on the assumption of a pure aerobic metabolism to calculate Ė , we could not investigate f p greater than 70 rpm in the water. This, together with the provision of longer recovery intervals in case of elevated postexercise [La], was also crucial to minimize fatigue and the slow component of the V˙O 2 kinetics (23,24) throughout the protocol. However, we still cannot rule out a minimal effect of fatigue, especially in those subjects who completed the study on a single day, although the randomization and balancing of the exercise bouts intrinsically mitigates this possible bias.…”