A surge of pain

Exercises	Duration	Sets	Reps
Treadmill	24:34 mins	1	5km
Dumbbell Shoulder raise (Side)		3 (Weight used: 8kg)	10
Dumbbell Shoulder raise (Front)		3 (Weight used: 8kg)	10
Dumbbell Shoulder raise (upwards)		3 (Weight used: 8 kg)	10
Crunches		3	70

Workout Date: 7th Jan'09

Workout Time: 1200hrs - 1300hrs

Venue: Gym

Went to the gym alone today. While I was on the treadmill, I suddenly felt a surge of pain at my heart at the 4th km. The speed I was at was 13, and I immediately slowed it down to 10 and took a few deep breath and continued to run at 10 for about 300m before the pain subsided. I then resumed running the remaining 700m at the speed of 13.