If you think you will become a better runner by running hard every time you step out to train, think again. Running slow or easy actually helps build endurance and strength, and prepares your body to run faster.

The slow, steady or endurance run is a crucial part of the training process for distance runners. Physiologically, slow runs increase bone density, improve fat burning and endurance, strengthen the heart, while stimulating the formation of new blood vessels. Biomechanically, a slow run improves the running economy (RE). By doing endurance runs, you also reduce the risk of injuries. If you want to keep growing as a runner, you would need to include slow running in your workout. 

A simple way to determine if your pace is slow enough is the talk test. If you can have a conversation with your running partner without feeling out of breath, you are running at a sufficiently slow pace or what is also called the “conversational pace”.

Also read: Can Strength Training Make You Run Faster?

Benefits of a slow run

1.Efficient use of oxygen

The heart muscle is responsible for pumping oxygen-rich blood to the muscles for use in the production of energy at a cellular level. Regular exercise at a low heart rate (HR) improves the stroke volume or the amount of blood the heart can pump with each beat. This means that more oxygen is available to your muscles with each heartbeat. 

2.Burns fat instead of carbs

When your body adapts to aerobic, slow runs, it gets trained to store glycogen and burn fat, utilizing the latter as a source of energy instead of carbs. To burn fat, more oxygen is needed. Your body is able to constantly replenish oxygen levels to produce energy without crossing the aerobic threshold.

Prolonged running at low intensity causes the muscles to release a cell signaling compound, interleukin-6 (IL-6), which contributes to fatigue. Well-trained runners produce less IL-6, so they are more fatigue resistant. 

3.Improves running economy

An extremely important benefit of the slow run is an improved RE. The more you run, the better you get at it. RE is measured by the oxygen cost of running at a certain speed. Two runners can have exactly the same VO₂max (maximal oxygen uptake), but the one with the better RE will be faster. Every step you take allows your brain to fine-tune your running and reduce its energy cost — this is why RE continues to improve over many years. 

If you want proof, look no further than Britain’s Paula Radcliffe, whose improved RE made her the world’s fastest female marathoner. Between 1992 and 2003, Radcliffe’s V02max remained roughly the same year on year, but her running economy improved by 15%. In 2003, she set a world record at the London Marathon clocking 2:15:25 hours. Her record was broken after 16 years by Kenyan runner Brigid Kosgei at the Chicago Marathon in 2019, when the latter clocked two hours 14 minutes 04 seconds.

4.Reduces stress

Running at an easy pace is less stressful for the body and the mind. Training above the aerobic threshold builds up stress over time, and your body starts utilizing muscle glycogen. This leads to fatigue and cramps. A good slow run will leave you feeling refreshed and positive. 

Also read: Different Types of Runs and How To Build Them Into Your Training Program

Training  for a slow run

Maffetone method

Author-researcher Dr Phil Maffetone introduced the world to the Maffetone method, which uses heart rate (HR) to regulate slow running. It’s a simple formula: subtract your age from 180 to get your base HR. Then use it and an HR monitor to keep your running pace slow enough so as to not exceed the HR. This ensures you exercise aerobically and utilize enough oxygen to burn fat. The only time you exceed this value is during a race. Maffetone sets no limit for racing — you race as hard as you can for the distance. 

Lactate threshold heart rate

Lactate threshold heart rate (LTHR) is the pace at which you cross your aerobic threshold and the body switches to the anaerobic system for energy. This results in excess lactate accumulation in your blood. The lactate threshold is a useful measure for training in heart rate zones. There are a number of methods of testing LTHR, including lab testing. This is, however, recommended for experienced runners and not beginners. 

30-minute time trial

A 2005 scientific study established the 30-minute time trial method as an accurate manual for slow running. Begin with a 15-minute warm-up and end it with five or six pickups (strides). Next, run hard consistently for 30 minutes. Beware not to start out too fast. Press your lap button 10 minutes into the run because you only want to measure the last 20 minutes. Your average heart and pace for the last 20 minutes of the test are your lactate threshold pace (LTP) or threshold pace (TP), and LTHR, respectively. Your lactate threshold will improve with training, so do test it periodically. 

Zone-based training

Now that you have established your LTHR and TP, how do you use them for slow running?

Zone-based training splits your efforts into separate, organized zones that range from easy to intense.

In LTHR terms:

1. Zone 1 (60%-75% of LTHR) is known as the recovery zone. 
2. Zone 2 is the aerobic zone (75%-85% of LTHR). 

Slow running is either in Zone 1 or Zone 2. Many fitness watches calculate your zones once you manually log in your LTHR. 

The other widely used method is to estimate your maximum heart rate (MHR) and then base training zones on that estimate. There are a number of formulae to determine MHR. All HR monitors will apply some sort of estimation to calculate your max. The HRMax Calculator created by the Norwegian University of Science and Technology is a useful tool to estimate your MHR. Slow runs will, as for LTHR, be done in the Z1 (55%-65%) of MHR and Z2 (65%-75%) of MHR. 

Rate of perceived effort 

The rate of perceived effort (RPE) is a subjective sense of how fast you are running where one is no movement and 10 is maximum effort in a 10-30-second sprint. An easy or slow running conversational pace would be rated between 4RPE and 5RPE. 

The table above is applicable to all levels of runners — novice, intermediate, or elite.

The actual running pace is a useful measure if you know your threshold pace. There are a number of online calculators that use threshold pace. One such calculator can be found at 80/20 Endurance. For maximum benefit, keep your slow running in Z1 or Z2.

Slow running has tremendous benefits. To improve your running economy and become a better runner, you cannot always train hard — this will, in fact, prove detrimental in the long run. If you want to increase your running speed, the mantra is to go slow. 

To know more about the science behind running slow, you can listen to our podcast, Run with Fitpage, where Jay Bawcom ,a USATF certified running coach discusses the importance of running slow.

References
1. McGehee JC, Tanner CJ, Houmard JA. A comparison of methods for estimating the lactate threshold. J Strength Cond Res 2005; 19: 553–8. 
2. Maximum Heart Rate Calculator. Norwegian University of Science and Technology. https://www.ntnu.edu/cerg/hrmax (accessed Mar 18, 2021).
3. 8020 Endurance.com https://www.8020endurance.com (accessed Mar 18, 2021).
4. Jones AM. The Physiology of the World Record Holder for the Women’s Marathon. Int J Sports Sci Coach 2006; 1: 101–16.
5. MAF Method. MAF. https://philmaffetone.com/method/ (accessed Mar 18, 2021).