When running, especially in areas of varying inclines, is it faster to keep a consistent pace or consistent effort? In other words, should a runner put more effort into up-hills or slow down to maintain the same amount of effort?
In order to answer your question, it is worth considering our understanding of the relationship between running economy and performance. Running performance is generally, but not always, associated with running economy. And whilst economy is a “complex, multifactorial concept,” two of its most important determinants are stride rate and stride length, whose product is speed. Both of these factors can be trained, and selected.
(The success of North and East African runners appears not to be associated with economy, and can therefore be assumed to be the consequence of fixed factors such as body geometry.)
It is well established that self-selected stride length is normally the most economical—a fact which is illustrated by the observation that deviation from self-selected stride length results in higher ratings of perceived exertion (RPE). That is, well-trained athletes tend to select a stride rate and length that is most economical, and any change to those variables results in both a loss of economy and a rise in perceived exertion.
This would suggest, therefore, that in order to achieve optimal economy and performance, we should maintain our preferred (self-selected) stride rate and length. On level ground, that would imply a constant pace. However, on undulating ground, maintenance of stride rate and length requires us to compromise other determinants of running economy. Our normal horizontal stride length is necessarily shortened running uphill and lengthened running downhill, further altering factors such as balance, flight and contact times, as well as concentric and eccentric loading—the latter of which greatly influences fatigue. And on any significant grade of hill, it is plainly infeasible to maintain our median pace (or speed) without incurring significant oxygen debt.
In order to achieve optimal economy and performance, therefore, we should maintain a constant effort or rating of perceived exertion, since this represents the most economical use of our physical resources, whilst simultaneously avoiding those factors that lead to fatigue.
Although there is a paucity of literature investigating this phenomenon specifically for running, it is well established in the sport of cycling. It is entirely plausible, of course, due to the relative complexity of the interaction of the runner with the ground, as compared with cycling, that there might be distinct ‘ideals’ of approach to horizontal, inclined, and declined running—a notion that appears to be supported by research showing that orienteers, who routinely train on heavy terrain, exhibit better economy than track runners when they transition to hills.
I hope that is helpful.
Distance running is all about pacing. You will run way slower if you gas yourself out too early and have to continuously slow down for the remaining of the run because you become increasingly tired. However, if you pace yourself early in the run, you will have enough energy to finish harder in the later portions of the run.
With regards to inclines in outdoor running. If you are running a track where the start and end are at the same point (typical with races), then the elevation up will be equivalent to the elevation down. The rate of change may be different, but that doesn't much matter. So, you can use this to your advantage and pace yourself in the uphill portions and put extra effort on the downhill. You could even just put in regular effort in the downhill and you'd still make up some time. You then may find that you'll have enough energy to maintain pace in the flat portions.