Physiological determinants of best performances in human locomotion

In human locomotion, the metabolic power required ((E)over dot) to cover a given distance d, in the time t is set by the product of the energy cost of the locomotion (C), i.e. the amount of metabolic energy spent to move over one unit of distance, and the speed (nu = d t(-1)): (E)over dot = C nu = C d t(-1). Since, for any given d, nu is a decreasing function of t and C is either constant or increases with nu, it necessarily follows that (E)over dot is larger the smaller the value of t. Thus, for any given distance and subject, the shortest time will be achieved when (E)over dot is equal to th e individual maximal metabolic power ((E)over dot (max)). In turn, (E)over dot (max) is a decreasing function of t: it depends upon the subject's maxi mal aerobic power (MAP) and on the maximal amount of energy derived from th e full utilisation of anaerobic energy stores (AnS). So, if the relationshi p between C and nu in the locomotion at stake and the subject's MAP and AnS are known, his best performance time (BPT) over any given distance can be obtained by solving the equality (E)over dot (max)(t) = (E)over dot(t). Thi s approach has been applied to estimate individual BPTs in running and cycl ing. In this paper, the above approach will be used to quantify the role of C, MAP, and AnS in determining BPTs for running, track cycling and swimmin g. This has been achieved by calculating the changes in BPT obtained when e ach variable, or a combination thereof, is changed by a given percentage. T he results show that in all the three types of locomotion, regardless of th e speed, the changes in BPT brought about by changes of C alone account for 45-55% of the changes obtained when all three variables (C, MAP and AnS) a re changed by the same amount.