Loss of Speed

edited September 2012 in Running Science

I have been running for more than 2 yrs now. Started running to help lose weight and quickly caught the bug for more.

I have never been fast, I wasn't able to build on any running experience from my youth, but with about 16 months under my belt (and 75 lbs lighter) I was able to post a few sub 24 minute 5k's. I have been training for my first marathon and I am currently 10 weeks through a 20 week training program.

My problem is a lack of speed. It seems that once my mileage increased to more than 25 - 30 miles a week I just lost all ability to run 8-9 minute miles. The best I have been able to accomplish is 10-11 minute miles. What gives? I don't feel tired or even really that sore, but it is like a switch was turned off in my running. I don't expect my quicker mile times on long runs, but a short mid-week run of 4 miles should be at my normal pace.

I know that my times will be considered pedestrian by many readers on this site, but considering I was a 275 lbs smoker, I am pretty happy with even being able to run. But it is still frustrating to post times that I was accomplishing a year ago. Any thoughts?

I was wanting to hear from anyone who may have/had the similiar delimma of loss of speed.


  • Dear bkingard,

    Congratulations on the weight loss and on quitting smoking! I'm also an ex-smoker and running helps me tremendously to stay away from that dangerous habit.

    Some ideas I have about your issue:
    1. The loss of speed could be because of overtraining, but this seems unlikely because you don't feel tired and you enjoy your running.

    2. A dietary cause (e.g. low iron) should also be considered.

    3. If you increased you weekly mileage fairly quick, than the lack of speed might just be your body's way to deal with all this extra strain. 

    4. What about the weather? It's been summer (Northern Hemisphere bias). Higher temp=slower running... When did you do your last fast 5k?

    5. You talk about "my normal pace". Can you still talk during your normal pace? At least 70% of your running should be at 'conversational' pace. Slow=good. Save your 5k race pace for speed work: a weekly interval session with the fast bouts being about 5 minutes with about 90s rest in between.

    Good luck!


    Source: a stew of internet & personal running experience flavored with some Jack Daniel's running formula

  • I agree with Will's comments - combo of cumulative fatigue with a marathon buildup possibly with summer heat will do it. Feel any better now that it's cooling down outside?
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