Runners new to longer distances often ask how long their longest training runs should be. Some seasoned runners say they prefer to do long runs that are longer than their goal race, so that the race feels a bit easier. So, for marathon training that might be thirty miles or more. Another approach I have seen is to run for a slightly longer time than the anticipated race plan, but since the run is done a bit slower that race pace the distance will be less than full race distance. Most experts I know of recommend eighteen to twenty miles for the longest run. It might be that an eighteen mile run done right will take about as long as a marathon at race pace. Let's do some math.
Marathon time goal 3:30, avg pace 8:00 min/mile
Long run pace 1:30 below race pace = 9:30 min/mile
18 miles at 9:30 =2:51.
That's about right, just under three hours.
There is precious little agreement on how much slower long run pace should be from race pace. The value of 1:30 slower is in the ball park. The critically important thing is to put in the distance without taking on too much fatigue.
Run workouts are measured by duration as well as distance. At least one coach, Matt Fitzgerald, prefers to specify short runs by time and long runs by distance.
A long run is simply an extended foundation run that is measured in distance instead of time. Somewhat arbitrarily, I place the minimum long run distance at six miles. With most workouts, time is a better way to give runners of different abilities an equal challenge ... but long runs are different, because their job is to build the endurance needed to cover a particular race distance. (Matt Fitzgerald, 80/20 Running, Ch. 7. )
Whichever way it is done, the other number is a result of pace. If a plan calls for a thirty minute foundation run and the runner does it at a 15:00 min/mile pace, she will cover two miles. If the plan calls for a five mile foundation run and the runner uses the same pace it will take her an hour and fifteen minutes.
How do we answer the question about how long the longest run should be, based on time? Do we just plug in the expected pace and go with that? An eighteen mile long run at a 15:00 min/mi pace will take four and a half hours. The simple answer is, no. The problem here is fatigue and stress.
The long run should be at a distance and pace that applies just the right amount of stress, without overdoing it. Doing the longest long run of marathon training as eighteen miles at 1:30 min/mi below race pace is intended to create just such an outcome. Hard, but not so hard that the runner cannot complete their weekday runs.
Everywhere I look, reputable sources say that a long run should be limited in duration. The same is true for other types of workouts, only the times will vary -- longer for bike rides, shorter for swimming. There is little agreement as to exactly how long, but but for the run, three hours is where I put the general consensus. In our example, the eighteen mile run should take just under three hours. That sounds about right.
The longer time spent running, the more fatigue is created. The only response is to rest. A well designed training plan should allow one full day off after the long run, or, for an advanced runner, maybe a short easy run. When the long run goes past three hours, the fatigue deficit becomes so deep that it can require several days, even a week or more, to recover. These gaps in training take away from the overall weekly progress.
An equally important reason for the three hour limit is injury prevention. The fatigue we feel coming over us during a workout is caused in part by the damage being done to muscles, tendons, ligaments, and bones. When we are sleeping, the body shifts into repair mode, and as it repairs the damage it makes the surrounding area stronger. If we run too long we tear down the repairs and end up going in circles without seeing any improvement. Sometimes even worse things happen, like shin splints or plantar fasciitis; repetitive stress injuries that set us back days if not weeks in our training.
There is another angle to this, the stress-response cycle. I'll just stop here without going into that any deeper and say that there is plenty of evidence that excessively long workouts are a bad idea.
The way all this affects me is that my long run pace is too slow to allow me to achieve traditional long run distances. I designed my marathon plan with an upper limit of three hours maximum run time, and to supplement my Saturday long runs with long bike rides on Sunday. Here is my twelve week plan, just the weekends, with a run on Saturday and a bike on Sunday. Included in this table are two events that disrupted the "perfect" schedule. These are the typical intrusions we all face in trying to stick to a plan. My longest run came in week eight, and was only twelve miles. The concert in week nine was special for me in that I had to sing in every piece but one, and for that one I had to drum, which is not unlike being the conductor. This concert took a lot out of me, and I had to go in well rested, about the same as doing a race.
The TrainingPeaks Annual Training Plan offers a good way to compare plan and actual. The Performance Management Chart offers more detail but lacks the planned data. Below is an excerpt from my ATP. The B race is the Century Ride, the A race is the marathon. The yellow line representing form also reflects fatigue; the lower the line, the more fatigue has accumulated. Peaking, a.k.a. tapering, is all about shedding fatigue.
Solid blue = planned Fitness (CTL)
Blue line = actual Fitness
Solid yellow = planned Form (TSB)
Yellow line = actual Form
Bars = planned and actual weekly TSS
The key thing is how well the blue line (actual fitness) follows the solid blue curve (planned fitness.)
Race day values:
Planned Fitness = 72
Actual Fitness = 76
Planned Form = 34
Actual Form = 24
The paradox I face is this. I have enough muscular endurance to run for about six hours at a very slow pace. This year that was 17:30 average, closer to 16:30 running flat, slower going uphill and dodging traffic. My legs called it a day around mile 20, so I walked most of the rest, managing slightly better that 20:00 min/mi. I did manage to run the length of Kapiolani Park, all the way to the finish. That gave me an 8:08 finish time. If I run any faster, the time to exhaustion will decrease. I don't think I will make up enough time so that I will cover the distance before TTE hits.
I did my first marathon in 2012. Missed 2013 due to a hernia operation that fall. My best marathon time was in 2014. The data for that run is surprisingly smooth, start to finish. Compare this year with 2014.
2012 - 7:50
2013 - hernia
2014 - 7:25 PB
2015 - 7:37
2016 - 8:20
2017 - 8:10
2018 - 8:08
Two things stand out about those first four years. I was not doing triathlon training, and therefore running a lot more, and I was using a run/walk technique. I think I should go back to that, the run/walk thing.
Only, there is this. The leading proponent of the run/walk method is Jeff Galloway. If I read his charts correctly, my run/walk times should be run 5 sec / walk 30 sec. Huh? That makes no sense at all. I was doing, as I recall, run 4 min / walk 1 min. He seems to prefer a 30 second walk break, nothing longer, but 4 min / 30 sec is recommended for someone running at an 8:00 min/mi pace; twice as fast me me. Obviously more to be done here, but I am considering it.
I still have not decided to run the marathon next year. Stay tuned!
I did my first marathon in 2012. Missed 2013 due to a hernia operation that fall. My best marathon time was in 2014. The data for that run is surprisingly smooth, start to finish. Compare this year with 2014.
2012 - 7:50
2013 - hernia
2014 - 7:25 PB
2015 - 7:37
2016 - 8:20
2017 - 8:10
2018 - 8:08
Two things stand out about those first four years. I was not doing triathlon training, and therefore running a lot more, and I was using a run/walk technique. I think I should go back to that, the run/walk thing.
Only, there is this. The leading proponent of the run/walk method is Jeff Galloway. If I read his charts correctly, my run/walk times should be run 5 sec / walk 30 sec. Huh? That makes no sense at all. I was doing, as I recall, run 4 min / walk 1 min. He seems to prefer a 30 second walk break, nothing longer, but 4 min / 30 sec is recommended for someone running at an 8:00 min/mi pace; twice as fast me me. Obviously more to be done here, but I am considering it.
I still have not decided to run the marathon next year. Stay tuned!
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