Speed and Body Weight

I have been asked the question; “How does body weight affect speed?” several times lately. Most of us know that a few extra pounds will affect our running performance, but just how much and in what way?

Extra body weight affects our running performance in several ways. Depending on how much extra weight one has it can affect “running efficiency” by causing one to shorten their stride or alter their upper body’s normal position over the legs in order to handle the weight. Endurance is affected because the muscles tire more quickly the more weight they have to handle. VO2max, sometimes referred to as aerobic capacity, or the measure of the body’s ability to consume oxygen and supply it to the muscles for fuel is affected. While most of us cannot afford to have our VO2max tested, it can be approximated using Dr. Jack Daniel’s VDOT chart. This chart combines running efficiency with VO2max to give an approximation value based on ones time for a given distance. It is not quite the same as VO2max but it can be used as a close approximation. The reason that it differs is that while two people of identical size, sex and weight may have an identical VO2max they may differ as much as 15 minutes in a 10K race because one has a much better running efficiency than the other one.

                                           Below is a part of Dr. Jack Daniel’s VDOT Chart.

Let’s say that an individual is at 185 pounds and a body fat percentage of 23%. This would put him at the outside edge of healthful but by most people’s standard somewhat overweight. An elite male runner would have a body fat percentage of about 4-6% and an elite female runner about 6-10%. Now let’s say that since our 185 pound male is not going to be an elite runner he only wants to get down to 12% body fat. Assuming that his muscle and bone structure remain the same this would take him down to about 162 pounds. Now let’s say that he recently ran his best 10K race, on a flat course, in a time of 1:03:46 putting him at a VDOT of 30. Six months later he is a lean, but not extremely low, weight of 162 pounds. We can predict his new 10K time by using the formula for VO2max of ml/kg/mn i.e. milliliters of oxygen per kilogram of body weight per minute. Using VDOT as VO2max or milliliters of oxygen we multiply 30 by 84.1 (body weight in kg’s) and get a product of 2522.73. If we now divide our answer of 2522.73 by our new body weight in kg’s of 73.63 we find a new VDOT value of 34.26. According to our

chart he should now be able to run a 10K in an approximate time of 57:26 or 6 minutes and 20 seconds faster than his previous time. He lowered his race time by approximately one minute per mile by loosing 23 pounds. In his case, that works out to about 2.66 seconds per mile, per pound of body weight. Of course this is not really that linear but only an average.

The example above only put VO2max into the equation if he also improved his running efficiency and gained more endurance because his muscles didn’t have to work as hard for the same distance his time would probably be reduced at least another half second per mile or more per pound of body weight, and all this without doing speed work. Now add speed work to the equation and the sky is the limit! Well almost!

There are other factors that go into this i.e. if you could loose 23 pounds immediately you could not expect to get all of this result right away as you would still have to get your legs and your nervous system used to going this pace. However, you would reap about 80% of this benefit almost immediately and the rest would come in as little as 4 weeks. I hope this has inspired some of you to loose a little of that extra weight that you really don’t need. By the way when you are loosing weight quickly, and running at the same time, you can expect to feel a little sluggish at times, as it is hard to keep the glycogen in your muscles and loose weight fast. If all you are loosing is a half-pound to a pound a week you should be fine. Any more than that and you will probably find that you are feeling tired a lot of the time and your legs feel like they have lead weights attached to them. Either way it is well worth the sacrifice in the long run to get rid of any excess weight.

Other benefits of loosing those extra pounds:

1. You should be able to increase your weekly mileage with less risk of injury.

2. You will have more energy for other activities.

3. You will look and feel great!

4. You may sweat less.

Happy Trails,

Russ

Heart Rate Training and Racing

Heart Rate Training

In order for one to get the most out of Heart Rate Training (HRT) one must first find their true Maximum Heart Rate (MHR). I do not recommend using formulas to estimate your MHR because they can be off by as much as 20 beats per minute or more and this could cause one to be over training or under training depending on what the case may be.

Finding Your Maximum Heart Rate

The safest and best way to find your MHR is to have a stress test done by a health professional or a Sports Testing Center. This can be expensive and prohibitive for many. If you have had heart problems in the past you should have your doctors ok before trying to find your MRH. Assuming that you have been running for about 3 months or more with no heart related problems or history, your MHR can be reasonably determined by using a Heart Rate Monitor (HRM) and a stressful run. Start by warming up for 15-20 minutes at an easy run pace. After warming up completely, run at your 5K race pace (Usually about 1.5 – 2 minutes faster than your easy run pace) for about ¾ of a mile then run the last ¼ mile as fast as you can while watching your HRM occasionally. The highest reading you can achieve in this manner will be very close to your MHR. Note: “5K race pace” is the pace that you can maximally sustain for a distance of 3.1 miles without slowing down from leg fatigue.

Using Your MHR to Determine Your Training Heat Rate

Training Heart Rate (THR) is the Heart Rate (HR) that you will use for different types of training. Old school THR used a percentage of MHR but I believe that the better way is to use a percentage of VO2max as estimated by HR. The best method for calculating this is the Karvonen Method and you can find a calculator for this at this web site: http://www.fitzroy-bramble.com/fitness/id18.html

The formula, if you want to work it out on your own is X% = ((Max HR-Resting HR)*X/100)+Resting HR. To find your Resting Heart Rate (RHR) it is best to take it in the morning when you first wake up and before getting out of bed. Some athletes even wear their HRM in bed so they can get a reading without moving much at all when they wake up. This may seem extreme but for serious athletes it can help them know when to cut back on their training. A resting HR that is 10 beats or more above normal is an indication of over training or illness and one should either skip their workout for a day or two or cut way back on distance and intensity.

After you have determined your MHR you can use the calculator at the web site above to determine you training zones for your workouts. If possible it is good to get in an Aerobic Threshold (AT) workout and a VO2max workout each week.

Remember that racing counts as a speed workout with half-marathon to 10K being AT pace and 5K or shorter being VO2max pace. The following chart would be an ideal week for an intermediate to advanced marathoner at 60 miles a week. The total daily miles include warm-up and cool-down along with the workout distance all to be done in the approximate allotted time. Taking Tuesday as an example, warm-up would be about 1.5 miles then the 1mile intervals and then about 1.5 miles of cool-down for a total of about 10 miles. This runner would be about a 3.5 hour marathoner.

3.5 Hour Marathoner / Max HR of 186

 

4 Hour Marathoner / Max HR of 186

While doing the 400 meter repeats the HR may not reach the target zone until half way to the end of the workout but it should climb a little higher on each succeeding attempt. Also one who is not used to doing these repeats and intervals will find it difficult if not impossible to do that many at first. If you are just starting out it would be a good idea to only start with about 4-6 repeats and add one or two each week or so until you can handle the full 16 repeats. Also Tuesday and Friday workouts can be swapped. Just make sure that you don’t do these types of workouts two days in a row except for on occasion. There is a time and place for Hyper-training but only on occasion and then you need to take several easy or off days following these double sessions.

Heart Rate and Racing

5K racing is usually done at a HR of 90-95% of VO2max while 10K racing is usually done at a HR of 88-92% of VO2max. Half-marathon is run at approximately 83-88% of VO2max and the Marathon is run at 80-85% of VO2max. Some elite athletes have been able to run the marathon at close to 90% of their VO2max.

Easy and Long Run Training

Easy running is 80 – 90% of the running that a runner does. This is the range which produces a training effect but doesn’t overly stress the body so as to cause it to break down unless one runs too many of these miles too often or builds up to running a high number of miles too soon. This running is done in the 60 – 70% of VO2max range. Generally the higher number of miles one can build up to running in a week, without over training, the better the results one will get from their running. It is best to build a strong base mileage before beginning a speed program. This base of weekly easy mileage is the core of your strength as a runner. How much is enough? To reach your maximum potential as a marathoner you would want to try and build up to 50 – 100 miles a week or more.

It has been shown that there is no more “aerobic” benefit to running more than 70-75 miles a week, i.e. it will not increase VO2max, nor will it increase mitochondria. However, for the elite athlete there may be a psychological advantage to running more miles, as many seem to perform better with 100 miles or more a week. My advice is to gradually build your weekly mileage until you feel that you are not getting anymore benefit from adding more, or until you feel that more would be pushing yourself too far and stay at that point or even back off just a little. When building mileage one should back off or stop speed work altogether until they have settled into their new mileage for a while. Never increase both at the same time. You will be asking to get injured by doing so.

AT Training

We mentioned earlier about (AT) or Aerobic Threshold. This is the point at which the body starts to produce Lactic Acid at a rate to fast for the body to get rid of and so it begins to build up in the blood stream causing leg muscles to get that burning, tired feeling. For untrained individuals this can be as low as 60% of VO2max and for very highly trained athletes as high as 92% of VO2max.

AT training helps raise the threshold to a higher percentage of VO2max thus allowing the runner to go faster for a given period of time without building up too much lactic acid. Typically AT training is running for a time period of about 20-30 minutes at about 10 seconds slower than ones present 10K race pace. However, it is also beneficial to do four 5 minute intervals at 10K race pace with 1-2 minute jogs in between.

There has been some leaning of late to run longer AT or Tempo runs at about half marathon pace or about 15-20 seconds slower than 10k race pace. These run periods can be 30-60 minutes in duration.

VO2max Training

VO2max training is running at a pace that causes one to be at close to VO2max and MHR. Raising ones VO2max is of the greatest value in trying to reach your best potential as a runner. No one thing is more a determinant in ones potential as a runner than VO2max. This is the measure of ones ability to supply oxygen as fuel to the muscles. Probably the ideal VO2max workout is a 5K race. The next best workouts would be 400-meter intervals or repeats with very short recovery intervals usually no more than 1 minute.

Summary

Heart Rate Training can be a great asset in your training as a runner. Using a HRM you will always know what your effort is in your training and you can have confidence that you are in the training zone that you intended. However, I do caution on getting too dependent on your HRM. Try and guess from time to time what your effort is before looking at your HRM. In this way you will train yourself to begin to know by feel what is your effort.

Weather conditions can affect your HR and so it is a good indicator of how hard you are working. In hot weather your HR can be 10-20 beats faster for the same pace. In long distance races you would want to stay within or even lower your expectations as to your ability to maintain your normal HR when the weather is very warm.

When doing speed workout i.e. AT and VO2max workouts don’t pay too much attention to your monitor under warmer conditions. This is the time to be going by time more than by HR but it is still a good idea to know were you are under different conditions.

I have tried to be short and concise. In doing so I may have sacrificed some clarity. The purpose if this article is to be more of a primer on heart rate running rather than an in depth discourse on the subject. For more information I recommend the book “Heart Zone Training” by Sally Edwards. This book is a great overall how to on Heart Rate Training. She has also written other books on the subject for specific sports such as cycling and triathlon. 

Happy Trails,

Russ