A laboratory method for determination of anaerobic energy expenditure during sprinting

Highly trained sprinters, marathon runners and untrained male control subjects were studied during treadmill sprinting. After confirming a workload which elicited exhaustion in just over a minute (mean time to exh. = 64.6 +/- 2.5 sec.), each subject performed sprints of 15, 30, 45 and 60 seconds duration in order that their energy expenditure could be segmented per 15-sec. of sprinting time. During every sprint, O2 consumption was recorded by closed-circuit spirometry. Following each sprint, serial 30-sec. venous blood samples were drawn in order to determine the peak lactate concentration. Energy expenditure was therefore determined as follows: i) aerobic energy from increments in O2 uptake, expressed in Kcal; ii) lactacid energy from increments in peak lactate, with the difference between peaks utilized to calculate the anaerobic glycolytic contribution to that 15-sec. segment, expressed in Kcal according to Margaria; iii) alactacid energy, expended over the initial 15-sec. segments, from the difference between the total energy requirement per 15-sec. less the measured aerobic plus the lactacid contributions. The sprinters expended the greatest (p less than .05) anaerobic energy (46.2 +/- 5.1 Kcal) when compared to either the marathoners (31.6 +/- 5.7 Kcal) or controls (33.0 +/- 1.6 Kcal). The athletic groups demonstrated superior alactacid energy (sprinters = 21.4 +/- 4.4 Kcal; marathoners = 15.8 +/- 2.3 Kcal), both expending a substantial amount of energy from this source (20%) past 30-sec. In contrast, over the initial 30-sec. of sprinting, the control subjects had depleted their alactacid energy (12.2 +/- 3.3 Kcal). Only minor differences were observed in aerobic energy expenditure between the three subject groups throughout the sprint to exhaustion.