Does running dowhill speed you up more than running uphill slows you down?

no

any hills with a net elevation gain of zero will be slower than a flat run

No

this seems to make sense intuitively, but can any of you supple examples via numbers?

No.

Noakes investigates this question in "Lore of Running." I don't care to spend the time looking up the specific data. You can do that on your own, but the answer is no. Same goes for wind. Running into the wind slows you down more than running with the wind speeds you up.

I found this article:

http://jap.physiology.org/cgi/content/full/93/3/1039

It investigates the energy requirements of running/walking at different gradients.

This image (http://jap.physiology.org/content/vol93/issue3/images/large/dg0921828001.jpeg) should answer your question. The top graph is walking, and the bottom running. The y-axis is metabolic cost (J/kg), and the x-axis is the gradient at which they are moving.

You'll notice that at moderate gradients (-0.1,+0.1), the energy difference from running on flat ground is almost the same. This could be read to mean that at moderate gradients, the uphills and downhills will negate themselves. However, at larger gradients (lower than -0.1, greater than +0.1), the cost of moving uphill increases faster than the cost of moving downhill decreases.

So running downhill will probably never speed you up more than running uphill will slow you. At best the two will negate themselves. But, at higher gradients, running uphill will slow you down more than running uphill will speed you up.

Definitely not. Flat always better than rolling, still air always better than windy on a loop course (or track).

Boston, despite being net downhill, is harder than London/Berlin even if it has a tailwind. Case closed (except that we can also cite NYM).

Of course, one factor is that if you go 13mph on the flat and then go 12 up and 14 down, the wind resistance is greater with the uneven speed. Also, going half the time at 12 and at 14 yields 13mph, but going half the distance at 14 and at 12 yields less than 13mph average (algebra left as an exercise for the reader).

thanks for the responses!

According to Ron Daws, because of braking, runners lose more going uphill than they gain going downhill. That is why it is important to train running downhill.

Boston is an easy course. There is a lot of downhill and the hills are not much. It is hard only if you are not used to the downhills.

I think De Castella ran a minute faster there than his best time on the flats.

Guppy wrote:

Noakes investigates this question in "Lore of Running." I don't care to spend the time looking up the specific data. You can do that on your own, but the answer is no. Same goes for wind. Running into the wind slows you down more than running with the wind speeds you up.

There are some tertiary aspects to consider. I once ran a marathon with a tailwind that was almost equal to my pace. Thus there was no cooling effect from the wind and I overheated much sooner on a warm day. So this particular tailwind actually caused me to run slower, in fact I might have run faster overall if there had been a headwind for cooling.

This would be something interesting to test. A 1 mile race on an inclined course. One weekend have the runners run up, the next weekend have them run down. After several trials you should get definitive results about the difference.

The Comrades Ultra in South Africa alternates on an inclined course, doesn't it? What are the differences in pace between the up course and the down course?

Marathon, 10 best results (legal):

2:07:51 1 Boston MA 21 Apr 1986

2:08:18 1 Fukuoka 6 Dec 1981

2:08:37 1 Rotterdam 9 Apr 1983

2:08:48 3 Chicago IL 20 Oct 1985

2:08:49 4 Tokyo 14 Feb 1988

2:08:49 3 Boston MA 18 Apr 1988

2:09:09 3 Chicago IL 21 Oct 1984

2:09:18 1 Brisbane 8 Oct 1982

2:09:42 1 Rotterdam 21 Apr 1991

2:10:03 1 Helsinki 14 Aug 1983

Average: 2:08:56.4

He also ran 2:11 at Boston in 1990. I think that you've misrepresented the facts.

batondrop wrote:

The Comrades Ultra in South Africa alternates on an inclined course, doesn't it? What are the differences in pace between the up course and the down course?

As I understand it, they alternate years: one up, next down. The up years are generally faster.

It definitely depends on the course, if its mountains like today in King City @ Senior Men's Ontario XC Champs. then the answer is no. If its small hills then it evens out more. There is a lot of middle ground too between mountains and hills.

One interesting thing I've noticed is that on a moderately windy day, if you have a tailwind going uphill, and a headwind going down, you can actually run faster than on a calm day (due to tailwind help0ing up and leaning into the wind on the downhill negating the wind entirely). I have such a training loop where my best times are on windy days.

26mi235 wrote:

Of course, one factor is that if you go 13mph on the flat and then go 12 up and 14 down, the wind resistance is greater with the uneven speed. Also, going half the time at 12 and at 14 yields 13mph, but going half the distance at 14 and at 12 yields less than 13mph average (algebra left as an exercise for the reader).

These two are easiest to agree with (the fact that wind resistances are different and that speeds don't "add").

I'd like to add that if you just think about it in terms of your internal efficiency or economy, it's not possible for running efficiency to increase with speed. As the stresses on your body become larger, your body will become more poorly equipped to rebound all of the energy. So you lose more energy (through your achilles and so on) than you should when you're running fast than when you're running slow.