Here is another study looking at building training for soccer around sprints rather than long runs. In fact this study seems to indicate that repeated 40 metre sprints were more effective than longer intervals (4mins). It makes sense - football is about sprints, that do not usually go on longer than 40 metres. You don't run continually for 4 minutes in a game, so why train like that?
Sprint vs. Interval Training in Football.
The aim of this study was to compare the effects of high-intensity aerobic interval and repeated-sprint ability (RSA) training on aerobic and anaerobic physiological variables in male football players.
Forty-two participants were randomly assigned to either the interval training group (ITG, 4 x 4 min running at 90 - 95 % of HR (max); n = 21) or repeated-sprint training group (RSG, 3 x 6 maximal shuttle sprints of 40 m; n = 21).
The following outcomes were measured at baseline and after 7 weeks of training: maximum oxygen uptake, respiratory compensation point, football-specific endurance (Yo-Yo Intermittent Recovery Test, YYIRT), 10-m sprint time, jump height and power, and RSA. Significant group x time interaction was found for YYIRT (p = 0.003) with RSG showing greater improvement (from 1917 +/- 439 to 2455 +/- 488 m) than ITG (from 1846 +/- 329 to 2077 +/- 300 m).
Similarly, a significant interaction was found in RSA mean time (p = 0.006) with only the RSG group showing an improvement after training (from 7.53 +/- 0.21 to 7.37 +/- 0.17 s). No other group x time interactions were found. Significant pre-post changes were found for absolute and relative maximum oxygen uptake and respiratory compensation point (p < 0.05). These findings suggest that the RSA training protocol used in this study can be an effective training strategy for inducing aerobic and football-specific training adaptations.