Friday, February 03, 2017

How much speed do I need to run 5k in 22:45?

There's an interesting article published in 2014 on by Jeff Gaudette which addresses the issue of 'Speed verses Aerobic Endurance' — the question of how much short distance speed does one need in order to run a desired time in a longer distance race, be that a 5k or a marathon. John states that 'speed is rarely the limiting factor in how fast you can race, even for a distance as "short" as the 5K.' The limiting factor is aerobic endurance. A runner's 'speed' over 400 metres to 1k is pretty much set genetically. A distance runner's job is to run as close as possible to that speed for the time of the race (which could be as little as 13 minutes for a 5k or longer than 4 hours for a marathon). The 'secret' to fast distance racing is to be aerobically strong enough to hold one's speed for the distance of the race.

John says "there is a limit to how much you can develop your absolute speed. At some point, your body approaches its natural talent point and working to improve speed provides diminishing returns. Luckily, improving your aerobic capacity is virtually limitless." For myself, I still feel like there are big gains to be made in my aerobic capacity, even though I'm now running 80 or more kilometres per week.

So, how fast am I over one kilometre? This is something I haven't tested in a very long time. I think I will though, just to have that information. My guess is under 4:20 (I can run a 4:30 k split in the Parkrun). Now when I was very young (34 or so), I could run a training 1k in 3:09 and ended up racing the 5000m in 17:33 (3:31 per km). My 5k race pace was about 11% slower than my pace for 1k — I wasn't a great 'converter' of my 1k speed into a 5k time. Looking back to those days now, I can say for sure that I hadn't maximised my aerobic ability. A fast runner who was also aerobically strong might be 4 to 5% slower than their 1k speed in a 5k race. That is, if they could run 2:48 'all out' for 1k they could probably hold 2:56 pace for 5k race.

How much speed do I need to run 5k in 22:45? When I was 50 years old I ran 21:29 for the 5000m on the track when I could run 4:00 for 1k in training (about 7% slower for 5k pace than my 1k pace). Extrapolating from this information, presuming I could run 1k in 4:15 and was as aerobically strong as I was in 2008, I could expect to run 5k in 22:44. Now all I need is to be feeling good on a cool, calm day!

Training on the soft grass of Yarralumla Oval on a warm Monday evening


TokyoRacer said...

Interesting. Go for it! Glad to hear you're running 80k a week.

Anonymous said...

I agree with Jeff Gaudette that it is better to put most of your training effort into developing aerobic capacity together with the ability to minimise acid accumulation at race pace. However, I agree only partially with his statement that threshold runs and cruise intervals are what is require to achieve this Intense intervals also help develop aerobic capacity and ability to minimize lactate accumulation. It is probably most effective to do some intense intervals in addition to the threshold runs and cruise intervals. Varying the training diet encourages development of all of the different physiological factors that contribute to aerobic capacity. A monochrome training program allows your body to rely on the physiological factor that is already most strongly developed.

And the 80K per week will also help

Nonetheless, for the purpose of prediction, your 1 K pace will give you a good indication of what you should be aiming for in the 5K. Good luck in your quest for 22:44 5K.

Ewen said...

Thanks Bob. Ran a good 5k this morning (23:43) off that mileage, so heading in the right direction. Must say, it takes a while to get used to the mileage.

Canute, my quandary is to develop aerobic capacity without suffering any injuries. I'm worried about doing anything intense (besides the Parkrun 5k) until I'm comfortable with the higher mileage. I have started doing regular 'strides' sessions, which I feel is helping with neuromuscular coordination and having 5k goal pace feel comfortable.

Anonymous said...

You are right that avoiding injury is one of the most important aspects of training. In my experience threshold training presents a greater risk of injury than interval training, provide that you build up the pace of interval sessions gradually, warm up well before each session and avoid intense intervals when you are tired. Your present strategy of building up with strides is sensible, and you are wise to build up mileage safely before pushing the intensity.

Ewen said...

Thanks again Canute for relating your experiences. I will introduce some interval training at some stage in the future. Most likely 500m and 1k repeats and the like and will follow your advice to build into the pace of each interval and not do such sessions when tired. That latter point is my problem at the moment - I'm still not used to the mileage so day to day tiredness is still being experienced.

Running Raggedy said...

So what you are saying is that no matter how you look at it, one can't cut corners. You've got to put in the time and there's no avoiding those long runs. I get it. That said you'd be pleased with the weekly mileage you've built up to and run consistently now. I reckon that goal of yours will be bloody smashed and soon. Good luck mate.

Ewen said...

Mark, I think there's no avoiding consistent 'decent' weekly mileage. The long run doesn't have to be hugely long unless you're racing the marathon. I've seen training logs from elite East Africans that only had a long run of 75 to 90 minutes but their weekly mileage was 160 km and they raced 1500m to 10k.

Black Knight said...

Congrats on a very good weekly mileage.
When I was a runner I learned that after my 50s the speed work was dangerous for me and my knees.

Ewen said...

Thanks Stefano. Making training adjustments as we age in order to keep running is standard procedure I reckon. Luckily my knees have been fine and I can still do speedwork as long as I'm careful warming up and when running fast.