Bruce Protocol: 16 minutes 24 seconds, workload 19.4 METS. Apparently got pretty far before a short, but useful atrial flutter occurred (250 bpm). Result!
KM 1: 06:02 KM 2: 06:05 KM 3: 05:48 KM 4: 05:50 KM 5: 05:42 KM 6: 05:38 KM 7: 05:41 KM 8: 05:46 KM 9: 05:42 KM 10: 05:43 KM 11: 05:31 KM 12: 05:40 KM 13: 05:37 KM 14: 05:35 KM 15: 05:32 KM 16: 05:33 KM 17: 06:02 KM 18: 05:31 KM 19: 05:42 KM 20: 05:40 KM 21: 05:43 Half: 2:00:42 KM 22: 05:28 KM 23: 05:36 KM 24: 05:46 KM 25: 09:10 KM 26: 05:48 KM 27: 05:39 KM 28: 05:39 KM 29: 05:40 KM 30: 06:09 KM 31: 05:37 KM 32: 05:45 KM 33: 05:58 KM 34: 05:40 KM 35: 05:59 KM 36: 06:25 KM 37: 05:46 KM 38: 06:41 KM 39: 05:57 KM 40: 06:32 KM 41: 05:52 KM 42: 05:37 Ah well, another miss on the 4 hour barrier. Atrial flutter just after km 25 for about 3 1/2 minutes (plus 30 seconds to convince the ambulance crew to let me go...). Took it easy afterwards and quite enjoyed the run.
Two atrial flutter episodes at 3km and 5.5km, respectively (approximately 5 minutes each with peaks of 235 bpm according to HRM). Worst timing possible. Very depressing. Not quite sure whether to run next week...
Not that it matters, but km1=4:45, km2=4:43 and km3=4:50.