Seven conditioned post-pubescent male subjects (VO2peak = 2.8 +/- 0.1 l.min-1) performed three high intensity board training sessions per week for an eight week period, followed by ten days of reduced training (taper). Subjects performed a 60 second all-out test, on a Biokinetic swim bench ergometer, on five occasions throughout the duration of the study. Testing occurred pre-training (T1), during the third week of training (T2), during the sixth week of training (T3), following eight weeks of training (T4), and post-taper (T5). Performance parameters as well as oxygen deficit (OD) were recorded during the 60 second all-out tests for the assessment of anaerobic capacity. Time trials were completed at times corresponding to T1, T3 and T5 over distances of 75, 140 and 250 metres. Over the duration of the study improvements of 17 percent (p < 0.05) and 60 percent (p < 0.01) were observed for Biokinetic swim bench mean power and peak power, respectively. Improvements in mean power and OD reached significance after five weeks of training. Improvements of 11 (p < 0.05), seven (p < 0.05) and six (p < 0.05) percent were noted from pre-training to post-taper for the 75, 140 and 250 metre time trials, respectively. Peak oxygen uptake improved by five percent from pre-training to post-taper which was almost significant at the 0.05 level (p = 0.052). Mean power correlated significantly with the 75 (r = -0.74, p < 0.05) and 140 (r = -0.79, p < 0.05) metre time trials, indicating that in-water performance and Biokinetic swim bench ergometry are well related. The ten day period of reduced training had no effect on performance parameters assessed during the 60 second all-out tests. It was concluded that improvements in the anaerobic energy systems, and associated performance in short-lasting exercise of high intensity, can be induced within five weeks of high intensity training with no decrements in the aerobic energy system.