Whether you specialize in the mile or the 100-miler, easy runs are the indispensable foundation of training. In every sound training plan, low intensity sessions constitute a majority of your training. Why do easy runs matter so much – and how just how easy should you pace them?
The How & Why of Easy Runs
Why You Should Slow Down for Most Runs
Running too fast on easy days – even just a moderate effort – inhibits some of the desired adaptations. If you begin to accumulate lactate (evidenced by breathing hard enough you can only speak in phrases), you are working too hard. Lactate is a desired product in some workouts; however, producing too much lactate in too many runs slows down recovery and therefore hinders adaptation.
The intensity of easy runs falls below the aerobic threshold (or what is commonly called “zone 2”). Below your aerobic threshold, you utilize both fat oxidation and carbohydrates for energy production, which places less stress on the body. Your body elicits a series of physiological adaptations that improve both endurance and speed, including increased aerobic enzyme activity, capillary growth for the transport of more oxygen to muscles, and an increase in mitochondria. When you run above your aerobic threshold too often, you do not optimize several of these benefits.
How Easy Should Easy Runs Be?
Some definitions of easy pace define it in relation to race pace. There are flaws in this approach. One common error is defining an easy run as “1-2 minutes per mile slower than race pace” without clearly defining race pace. One minute per mile slower than 5K pace is likely still above your aerobic threshold and therefore not easy. Two minutes per mile slower than marathon pace for slower runners may be biomechanically uncomfortable. (For some marathoners, marathon pace may also be their easy pace.)
Training fatigue, your overall weekly mileage (and response to such mileage), your stress levels) muscle fiber composition (see more below), terrain, altitude, and other factors will affect the exact pace of easy days. Your easy pace will even vary day to day! Because of that, it is essential to use factors other than pace to gauge the intensity of your runs.
- 60-75% of max heart rate or <85% of lactate threshold heart rate (here’s how to calculate that)
- You can carry on a conversation; breathing is barely labored
- 3-4 out of 10 on the rate of perceived exertion scale
- Sustainable; finishing should not be a concern
- You feel comfortable and relaxed
A Majority of Your Runs Should Be Easy
Training intensity distribution is a hot topic in exercise physiology research. However, most of the debates center around how much threshold versus hard training should be done. The overwhelming consensus is that approximately 70-90% of your runs should be done at an easy, conversational pace. This emphasis on easy running optimizes aerobic adaptations – which are vital for performance in any distance longer than the 800m.
Your Muscle Fiber Composition Plays a Determining Role
Never compare your easy pace to another runner’s, even if they have the same race time. In my years of coaching, I see this regularly: two runners can have the same race times and the same workout paces, yet their easy day paces vary dramatically. One may cruise along at 45 seconds per mile slower than marathon pace; the other may run 1.5-2 minutes per mile slower than marathon pace.
A slow twitch athletes runs faster at a lower percentage of their VO2max, since they burn fat at higher intensities and can delay the recruitment of fast-twitch muscle fiber recruitment. Fast-twitch runners need to run slower on their easy days. Their bodies tend to quickly recruit fast-twitch muscle fibers, which are counter-productive to the goal of low-intensity training sessions.
Pace Will Also Vary with Training Fatigue
Your muscle fiber typology and current fitness are not the only factor. Your easy pace will vary day to day and within different phases of training. The fresher your legs are, generally the faster you will run within your easy pace range. If you are training for a race and completing long runs and hard workouts, you may be slower on easy days due to fatigue. Remember: easy is an effort, not a pace.
The Art of the Recovery Shuffle
A sub-type of easy run is the recovery run. Recovery jogs are slow – so slow that you may consider them more of a jog or shuffle than a run. The pace is typically 2-3 minutes (or more) slower than your lactate threshold and decently slower than your other easy runs. Realistically, though, you are not tracking pace on a recovery run. You simply shuffle along at an effort that feels slow and leisurely. You should feel better when you finish than when you start.
How do you know if you are going too slow? Most likely, you are not. An easy or recovery run is only too slow if you feel discomfort from altering your gait. For most runners, that is a lot slower than they realize.
Adding “Stuff” to Easy Runs
More advanced runners often add small, deliberate doses of faster bursts to some easy runs. This is not a license to bust out a fast final mile or throw in some tempo pace; those are workouts, not easy runs.
- Strides: Strides are short accelerations done after a run. While fast, the short duration and ample recovery control heart rate and prevent lactate production. Strides can be done one to three times per week – here’s how to do them.
- Surges: Essentially, surges are strides within a run. These are 20-30 second accelerations (short enough to not go anaerobic) with generous recoveries (1-3 minutes jog). These are not all-out sprints, nor is longer better.
- Moderate progressions: These are not hard workouts. A majority of the run is still within the easy zone; the final segment progresses into a moderate/steady effort, right at the aerobic threshold (roughly marathon pace for many runners).
- Hills: Most runners will benefit tremendously from running hills. You can incorporate hills into training runs. Focus on your RPE or heart rate on the uphill and downhills, since the physics of hill running will affect pace.