Benefits of heart rate training

Here’s an excerpt from my previous seminars and education on intensity training for our training program:

 “I'm asked from time to time why we need to do speed and/or tempo workouts in our marathon training. What's the point in training at different intensity levels, if the races that we do rely nearly 100% on our aerobic endurance capacity? During my USATF run coaching certification in November '07, I dove into the research on varying training intensity. Its importance is key to me as an athlete, and as your running coach. Just like many of you, I'm an active triathlete, endurance swimmer and marathoner (enthusiastic, if untalented). Over the years, I've done many triathlons, lots of marathons, open water swims, and innumerable running races of varying distances. And, just like many of you, I've relied on varying aerobic and anaerobic fitness levels, in order to tackle the demands of each race. In the endurance run training plans I've created for you, I recommend that you do only a few run workouts each week: 3-4x for half marathoners, and 4-5x for marathoners. Not more. And, that you vary those workouts, as speed, tempo and endurance. Each has a distinct purpose and objective. From a muscular-skeletal perspective, an important reason for doing so is to avoid overuse injuries. We want to allow lots of rest time between run workouts: to heal connective tissues, to reduce joint inflammation, and to replenish red blood cell counts. All of those help to rejuvenate our muscles and to prepare us for run workouts to follow.  And, while those muscular-skeletal considerations are critical, what about our aerobic fitness? What efforts must we make in order to maintain those critical systems?

Why do we train at varying intensity levels?

Here's a quick primer on aerobic and anaerobic intensity training, key benefits, and fuel considerations.

Aerobic threshold training is typically done at around 130-150 heartbeats per minute (bph). When training within this zone, our bodies utilize fat as the primary fuel source. Believe it -- fat is great! It is essential to us as endurance runners. I have [ahem] a bounty of it, in fact, along my belly. : ) Fat & fatty acids are efficient, slow burning, endurance-focused fuel sources. During our long runs, we want to remain within this aerobic threshold zone. The benefits are obvious -- we are training our aerobic system to use fat and fatty acids as the chief energy source. That's key, as we are teaching our body to avoiding using its glycogen stores, which are critical for anaerobic levels (higher heart rate intensity). As endurance runners, we gradually "tune" our body to more efficiently burn fat as a fuel source. Over time, we improve and refine this ability. As result, we improve our aerobic endurance. And, we become more efficient, effective and economic distance runners!

Anaerobic threshold training is typically done at levels above 150 bph. Many of us do our long runs at Umstead, Falls Lake or other hilly routes. It is easy to spike our heart rates, and jump up into this anaerobic zone running in such places. Often we can't avoid it. Gotta get up the hill somehow. When we train at these levels, our bodies shift its choices of fuels from fat/fatty acids to glycogen. Those are carbohydrates in a variety of types, but are often ones that we bring along and utilize during our runs ... supplements like Gatorade, Gu packets, Power bar, gels. Even a candy bar. : ) The constant with all of these is a speedy burning fuel. Glycogen is quick fuel. Burns relatively fast. Doesn't last nearly as long as fat, but great stuff. Glycogen consumption is required to meet the high fuel burning demands of the body during the anaerobic training phase. I know that many of you have done track workouts, or hill repeats, a challenging spin class, a rigorous stair-climber workout, etc. You get the point. You likely know well this anaerobic zone. It stinks. Painful, difficult, a thumping heartrate, out-of-breath, and really uncomfortable. We did this a lot during our workouts at the track. Even my chipper, grinning presence at the track with you doesn't help. In fact, some of you wanted to physically hurt me for recommending such a tough workout. : ) Glad you didn't. During this high intensity level, lactic acid is created as an output. Bad stuff, it makes our legs soon feel like lead, particularly if our event is longer. But this training is invaluable! Why? We have to teach our bodies how to handle this acidosis. And, to train regularly within this zone helps us to teach our bodies to cope with periods of oxygen debt and lactic acid build-up. The benefits of training in this high range are obvious for folks doing shorter races, like 5k & 10k races, sprint/international triathlons, etc. I think we all understand that. But what about half and full marathoners? Well, you must also spend some of your workouts within this anaerobic phase. A key adaptation over time resulting from this type of work is enlargement and strengthening of the heart. It is, after all, really just a large, complex set of muscles. We improve its ability to operate as a living pump and its ability to transport blood and oxygen to the working muscle cells. That's important stuff, no matter the distance we run.

The training plans that I've created for all of you advocate weekly workouts in both aerobic and anaerobic threshold levels. Your speed workouts will usually be mostly anaerobic (during the mainset, not the warmup or cooldown jogs). Your tempo workouts will be anaerobic during the "up" periods, but will have a deliberately incomplete recovery in the "down" periods before you jump into the next tough "up" set. You get the point -- you are training your body to work within different levels. Over the coming weeks, I want all of you to gradually become more efficient, more effective runners as you teach your body how to distinguish each threshold rate, utilize distinct fuel sources, and run effectively even with effects of acidosis. A basic, inexpensive heart rate monitor is really handy for this -- as a guide to tell you where you're at, how long you've been in a given zone, etc. Many of you are triathlon training. What I've mentioned is even more critical to you!  Particularly those folks doing the sprint distance and international distance events. During your races, you'll rely on a combination of aerobic and anaerobic intensity during your race. So, you must consistently train at those levels.  Over many weeks.  So that you coach and teach your body on efficient energy utilization.

Happy running, folks. Enjoy the challenges of your workouts. We'll do this together, and enjoy our achievements together. For those of you new to endurance running, embrace the wonderful challenges ahead of you. For the many experienced endurance athletes among us, challenge yourselves this season to improve and refine your aerobic and anaerobic fitness”.

Jeffries

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References:

• Swain et al (1994) 'Target HR for the development of CV fitness' - Medicine & Science in Sports & Exercise, 26(1), 112-116
• Summary of Borg Scale:   http://sportsmedicine.about.com/cs/strengthening/a/030904.htm.    Research paper was:   Borg, G, "Perceived Exertion as an indicator of somatic stress", Scandinavian journal of Rehabilitation Medicine 1970, 2(2), 92-98
• Miller et al (1993) - 'Predicting max HR' - Medicine & Science in Sports & Exercise, 25(9), 1077-1081
• Sports Medicine 2004; 34(14):967-981
• Funny summary of the Borg Scale:    from Paige Waehner, contributer to about.com   http://exercise.about.com/cs/fitnesstools/l/blperceivedexer.htm
• Medicine & Science in Sports & Exercise 2007; 39(5):822-829
• Int J Sports Med 2007;24
• Londeree and Moeschberger (1982) 'Effect of age and other factors on HR max' - Research Quarterly for Exercise & Sport, 53(4), 297-304