Many runners stick to level running for a long time before they start training on inclines and declines. After all, level training is easier, more convenient, and perfectly effective if you want to improve your cardiovascular health and fitness. At some point, though, most runners will want to start mixing some hill running into their training.  

Here, my guide to incorporating hills into your mileage.

The Challenges of Hill Running

Before you lace up your sneakers and head towards the biggest hill you can find, keep the following in mind: While running inclines is harder, running declines is more dangerous.

Let's start with inclines: Running uphill is obviously more difficult than running downhill–but it's also fundamentally different. As the incline you run up changes, so does the angle at which you move, and therefore the muscles that you use.  

Uphill runs actually resemble resistance exercises, particularly squats and calf raises, as the angle gets steeper.

In comparison, running downhill may seem like a breeze. However, running downhill is more dangerous for two reasons.

First, the obvious danger: You could fall, either by tripping over your own feet or shoelaces, or by slipping on whatever terrain you're covering (like dirt on a trail). The faster you run, the greater the risk. 

Second, the sneakier danger: repetitive stress injuries.  When you run, every step sends shocks up through your legs, putting your shins and knees at risk for injury over time. Since running downhill increases the distance your foot travels down with each step, it increases your risk for stress injuries in the long run. (Running uphill actually has the opposite effect.) The steeper the decline and longer your stride length, the greater stress on your lower body.

Given these factors, hill running can still be a safe and effective part of your routine. You just have to follow a few rules.

Rule 1: Be Mindful of the Terrain (And Your Shoes)

Since streets don’t usually features very steep inclines for very long (in most places), most people incline and decline run on hiking trails. 

If running on loose dirt, start off at a slower pace to ensure steady footing–especially on your first time running a given trail.  Of course, watch out for mud, as well. 

Related: 4 Signs It's Time To Get Rid Of Your Running Shoes

When running on surfaces other than paved roads, make sure you wear shoes designed for running on dirt or trails, which typically offer greater grip and support. Regardless of the terrain you're running on, though, replace your shoes as soon as the tread starts wearing down. 

Rule 2: Run on Shallower Grades Most of the Time

Though you make think steeper inclines and declines are always better, that's not actually the case.

The steeper the grade of the hill you run on, the less carryover effect that run has on your level running.  In fact, excessive training on very steep grades can lead you to develop running habits that won’t serve you well in other environments.  

Assuming you still want to boost your level running performance, focus most of your hill runs on lower-grade (a.k.a. smaller) inclines and declines. Save the steeper stuff for every three to four sessions or so.

Rule 3: Lengthen Your Warm Up and Cool Down

For the inexperienced, the new movement pattern and increased exertion of hill running can put you at greater risk of cramps.

To give your body ample time to prepare, begin every hill running session with at least five minutes of walking, followed by five minutes of slow jogging.

Related: 8 Great Core Exercises You're Not Doing

Similarly, end each session with a minute or two of jogging ,followed by at least three minutes of walking.  

Finally, follow up each hill run with five to ten minutes of stretching to help your muscles fully relax, clear out lactic acid, and ensure a speedy recovery.  

Rule 4: Use Short Strides

Remember, the longer your strides, the greater the height difference between where your feet land from one step to the next–and the greater the impact your body faces. 

Longer strides make incline running harder and decline running more dangerous. Shorter strides, though, make hill running easier and safer.  

Follow this rule of thumb: The steeper the grade (whether an incline or decline), the shorter your strides should be.  

Rule 5: Run at the Same Pace Uphill and Downhill

Though we naturally want to run fast downhill and slow uphill, I advise against it for a few reasons.

First off, there’s the safety factor I already mentioned: Running too fast downhill puts you at greater risk of injury.

However, there's also a pacing, or training adaptation, issue to consider. You’ll learn to run more efficiently if you practice pacing yourself and push to maintain your target pace while running uphill. (Instead of going faster on the downhills, maintaining your target pace will allow you to rest.)

Rule 6: Separate Incline/Decline Runs from Leg Training

I always recommend runners strength train with weights regularly, and while it's okay to do a level run on the same day you strength train (as long as they're a few hours apart), that's not the case with hill running.

As I mentioned, incline and decline running tax your legs–both muscles and joints–more than level running.  Often, a serious hill session provides a very similar stimulus to a gym session. 

Avoid training your legs in the gym on the same day you do hill runs.  On the days before and after a hill run, you can incorporate some lower-intensity sets, but should still avoid heavy leg training. Leave at least 36 hours between heavy lifting and hill runs. 

If you run hills on Thursday and Sunday, for example, you might do a light leg training session on Friday or Saturday, and your heavy leg session on Tuesday.    

Rule 7: Do One or Two Hill Workouts Per Week

Assuming you’re supplementing your usual level running with some hill runs, limit the hill work enough to maintain your focus on level running, resistance train regularly, and recover.

At first, limit hill training to about one one-hour session a week. After a month or two, you can increase to two sessions a week (as long as you feel recovered). Unless you want to focus specifically on hills, limit session to twice a week max.

Of course, if you are training for a hilly event, you might want to incorporate hills three or four days a week and cut back on level running and strength training to compensate.