Heartrate concerns. Should I be worried?

[MCAP]

I've never been very comfortable running. I have always gotten shin splints in the past and just stopped.

Now, although still heavier than I'd like, I'm in the best shape fitness wise probably in my whole life. I started cycling this summer and my aerobic fitness has improved 10 fold. I've been swimming too and my lung capacity is so much better.

I'm training lightly for triathlons next year with the goal of a half ironman in 2013. I've been running intervals of 1 minute running and 2 minutes walking once a week for a few months. This past week I did a full ironman challenge at my gym and ran/walked 26.2 miles over 7 days.

I noticed a couple of things that have me somewhat concerned. I feel like I'm in good enough shape now that I should be able to run farther/ longer between walks. Yesterday I walked a mile at 3.5 mph then ran 1 minute at 7.0 mph alternating 2 min walk at 3.5. In one minute running my heart rate got up above 180 and it was almost like I could feel the blood draining out of my body. Once I started walking I could recover rather quickly.

Why is my heartrate going so high when I run? It doesn't get near that high when I bike or swim unless I'm sprinting all out.

I feel like I can't go any longer than two minutes running or I'll risk passing out. I feel very weak after 2 minutes. I feel like it should be improving, but it's not.

If I run slower (5.5-6.5 mph) my knees and shins hurt. 6.5-7.0 allows me to get a full swinging stride with less pounding and I haven't had a much trouble with my shins hurting this go around.

What can I do to improve? I want to be able to run longer, but I just don't know what to think about this heart rate/weakness feeling situation.

Any thoughts?

[jessmarimba]

I would say that you likely do need to figure out how to slow down for your running intervals. It sounds like you've taught yourself what your body is considering a sprint, but most people can't extend their sprint pace beyond a certain length of time without going anaerobic. You may be able to adjust your gait so that your knees and shins aren't hurting - or you might need to get a pair of shoes that is better suited for your feet and your running style. Were you fitted for the shoes that you're wearing in a running store?

[KnottedYet]

I strongly (jumping up and down shrieking and pulling my hair out) suggest you check in with a sports medicine physician.

Feeling like you are going to pass out after 1 minute of running at 7 mph is probably something it is rather important to pay attention to.

Feeling like you are going to pass out during ANY activity is something to which one MUST pay attention.

[MCAP]

Yes, my running shoes were purchased at a running store after a professional gait analysis.

7.0 is only a little faster than a ten minute mile- certainly not a sprint. I feel very comfortable at this speed but feel like my body may just crumple out from underneath me after about a minute. My legs feel fine, my lungs feel fine, my head feels fine, but my heart races and my body gets weak.

I'm going to try to find a doctor to see about this. I'm very perplexed that it only happens running and not cycling or swimming. Perhaps it has something to do with running being weight bearing.

[colby]

Yes, my running shoes were purchased at a running store after a professional gait analysis.

7.0 is only a little faster than a ten minute mile- certainly not a sprint. I feel very comfortable at this speed but feel like my body may just crumple out from underneath me after about a minute. My legs feel fine, my lungs feel fine, my head feels fine, but my heart races and my body gets weak.

I'm going to try to find a doctor to see about this. I'm very perplexed that it only happens running and not cycling or swimming. Perhaps it has something to do with running being weight bearing.

7mph is an 8:30-ish min mi. An 8:30 min mi is significantly faster than a 10 min mile The likely case, as Jess suggests, is that that is closer to your interval pace than your regular "forever" running pace. What you describe sounds like an interval to me (well, a little beyond - Knot's right that feeling like you're going to pass out is pushing it) - it's hard work for a short period of time. You'll probably get better at them the more you do them, but you will probably not be able to run that speed for sustained periods for a while. If you want to run longer, you will probably have to run slower until your ability to run at those speeds increases. The intervals WILL help with that, so if you do introduce days with more extended slower running periods, you should keep up some faster intervals on other days, too (but maybe not to the point where you're lightheaded ).

I can definitely understand that your stride (and everything, really) is more comfortable at the faster pace. It does force you to stretch and land your feet differently and I also find this difficult to apply at lower speeds. I'm not sure there's a secret to that other than to improve your form - it might do your faster running speeds good to improve at slower speeds.

[OakLeaf]

In addition to what everyone else has said:

* "improving your form" isn't so easy to do without guidance. I'm a huge fan of Chi Running - which has DEFINITELY made it possible for me to run slowly without pounding myself to death. From a musculoskeletal standpoint, I'm as comfortable now at a 12:30 long run training pace as I am at an 8:05 5K pace or doing sprint intervals. That did NOT use to be the case. I don't really know much about other methods, but you might check out some of the free materials on the Chi Running website, pick up the DVD or book, and/or find an instructor or workshop near you.

* Your maximum heart rate for running will always be higher by 5-10 bpm than your MHR for cycling, and about the same gap to swimming. Sources I've read have speculated that this has to do with weight-bearing, cooling, or a combination of those.

* Cardio fitness only translates between sports to a certain extent. You still have to be feeding blood to unaccustomed muscles.

* Are you breathing efficiently when you run? It's definitely different than cycling breathing, and I would think that if you're not getting enough air, that might cause the symptoms you're describing.

Good luck - hope you find that it's nothing to worry about and that you get it sorted soon!