Some physiological demands of a half-marathon race on recreational runners.

The purpose of this study was to assess the physiological demands of a half-marathon race on a group of ten recreational runners (8 men and 2 women). The average running speed was 223.1 +/- 22.7 m.min-1 (mean +/- SD) for the group and this represented 79 +/- 5% VO2 max for these runners. There was a good correlation between VO2 max and performance time for the race (4 = -0.81; p less than 0.01) and an even better correlation between running speed equivalent to a blood lactate concentration of 4 mmol.l-1 and performance times (r = -0.877; p less than 0.01). The blood lactate concentration os 4 of the runners at the end of the race was 5.65 +/- 1.42 mmol.l-1 (mean +/- SD) and the estimated energy expenditure for the group was 6.22 M.J. While there was only a poor correlation between total energy expenditure and performance time for the race, the correlation coefficient was improved when the energy expenditure of each individual was expressed in KJ.kg-1 min-1 (r = 0.938; p less than 0.01).