My planned workout this morning was a one-mile warm-up followed by eight miles at my goal marathon pace of six minutes per mile. Despite the 90-degree heat, all was going well until, with less than a mile to go, I felt a sudden, sharp twinge in my right hamstrings. Five years ago I would have doggedly finished the workout according to plan--after all, I was so close to completing it, and the pain wasn't completely debilitating. But years of living to regret such stubborness has taught me that discretion is the better part of valor, so I immediately slowed to a jog and took the shortest way home.
I am confident that, thanks to my caution, I will be ready for an easy run tomorrow and ready also for my next planned high-intensity workout on Friday. If I had froced myself to run that last 0.9 mile at six-minute pace, who knows? I might have completely ruined my next two or three weeks of training.
Yup. This' what I should've done about 6 weeks ago. I was doing some 80-90m sprints on a hill, and the second to last one my left hamstring tightened some. I knew I had only one more, so I started it and before I got 20m, I had strained it. Bummer. Couldn't run for about a week or so.
Since then I've backed off once or twice (as you mention you did above) in workouts based on how I was feeling so I don't go over the from the 'pain' line into the 'injury' side of things. I think this has enabled me to be able to keep running. As a relatively new runner (2 years now), I hope I've learned my lesson, and I'll try to keep practicing the zero tolerance policy.