How Tired Should You Be After a Long Run?
The long run is a training cornerstone for runners who compete at all distances. Simply put, the long run is the longest run during a training week, one that challenges an athlete’s body to become more efficient. However, properly approaching the long run requires balance. You should not finish your run unable to function for the rest of the day, nor should you run so slowly that you are spending undue amounts of time on your feet. Here, the basic details of the long run will be examined.
Why Run Long?
The long run1 is a vital part of training because it helps a runner adapt – both mentally and physically – to the stresses endured while running. A long run should comprise 20 – 30% of your weekly training volume, but is also dependent on the length of the race for which you are training. For instance, a 5k or 10k runner should complete an 8 – 12-mile long run; a half marathoner should build up to a 12 – 16-mile long run; a marathoner should complete a 20 – 24-mile long run before race day. There are many benefits to the long run, which include:
Better Aerobic Base
Aerobic activity is exercise that primarily utilizes oxygen as fuel. The better an athlete’s ability to efficiently consume oxygen during activity, the better his or her endurance will be. The cardiovascular system makes important adaptations during periods of sustained running, and the long run is one of the most efficient ways to trigger these results.
A long run is a mentally and physically arduous task. Completing long runs week in and week out give runners more confidence in their ability to complete a specific race distance. For instance, a 20-mile training run takes approximately the same amount of time to complete as a 26.2-mile race. The long run helps a runner build confidence about being on his or her feet for that length of time.
Enhanced Running Economy
The body acts as a well-oiled machine and inherently prefers to waste as little energy as possible. Over time, the body will adapt to improve a runner’s economy so that as little energy as possible is wasted. This phenomenon can occur in the form of improved biomechanics or cardiovascular and cellular adaptations.
Increased VO2 Max
Many of the factors discussed in this section, i.e. better aerobic base, improved metabolism, and mitochondrial growth, all ultimately affect VO2 max2. An athlete’s VO2 max – the maximal rate of oxygen consumption during exercise – is an important variable when it comes to a runner’s athletic potential. The physical adaptations that a runner experiences during long runs all lead to an increased VO2 max.
Long runs can be lonely, boring, and difficult to find motivation to complete. During these long runs athletes are able to develop mental toughness strategies that are useful during races.
While the endurance athlete’s body utilizes carbohydrates in the form of glycogen and glucose for energy, utilizing fat for fuel can delay the body from tapping into these resources. During a long run the runner’s body creates necessary adaptations to improve metabolic efficiency3 for energy consumption.
The size and number of mitochondria4 – the organelles within a cell that create energy – increase as a result of running long distances. These mitochondria are important for efficient fueling during long and hard exercise efforts.
When a runner pushes his or her body to cover long distances, the necessary muscles in the calves, quadriceps, and hamstrings become stronger. These muscles are required for improving a runner’s efficiency while keeping him or her injury free.
Finally, long runs are essential for practicing the nutrition that a runner’s body will require during a long race, such as a half marathon or marathon. The best way to determine what works – and what doesn’t – is to test different nutrition products in real-running scenarios.
Factors that Affect the Long Run
Now that the long run has been defined, as well as the benefits of this practice, the factors that affect long run effort will be discussed.
Occasionally, runners voluntarily complete their long runs in a “carbohydrate depletion” state. These highly trained athletes do so in order to force additional adaptations in the body. However, these types of runs are not advised to be completed week in and week out because of the toll they take on the body. Simply put, running without adequate carbohydrates5 is significantly more difficult. Improper fueling makes an athlete more likely to “hit the wall” during the latter stages of the run.
Extreme conditions such as heat, cold, humidity, wind, and rain can all make the effort of a long run more difficult. These factors have a cumulative effect, meaning 80oF and high humidity will cause relatively more stress during an 18 mile run than a comparable 6 mile effort.
Another important factor is pace. Most coaches recommend that the long run be completed 60 – 90 seconds slower than marathon pace, or at a pace that is conversational. While running faster, such as marathon pace, is occasionally recommended, completing a long run too quickly can lead to extreme fatigue.
Like weather, terrain plays a large role in the effort put forth during a long run. Hilly and soft surfaces require significantly more effort than flat, hard ground.
Training has a cumulative effect on the legs, and heavy weeks of mileage or quality workouts can lead to long aerobic efforts that feel especially difficult, even at moderate efforts.
Finally, the distance of your long run relative your weekly mileage, as well as your total mileage, will affect the effort that you expend. A long run should comprise 20 – 30% of a runner’s weekly total. When this amount is exceeded, a long run can feel more difficult, due to inadequate aerobic fitness.
Appropriate Levels of Fatigue Following a Long Run
If you regularly experience the following signs, you are likely running your long runs at an appropriate pace.
Following a long run you should feel worn out, but not exhausted. A 30 – 60 minute nap, a good meal, and a healthy dose of caffeine should be all that is required to get your legs moving after your long run is complete. Exceptions include race simulations and extreme-distance long runs (20+ miles or 3+ hour runs.
If you train by heart rate, an easy way to know if you are running the proper effort is by maintaining 67 – 77% of max heart rate during the long run. For most runners, this equates to 148 – 162 beats per minute. If you do not train by heart rate, it can be beneficial to occasionally take a break throughout the run and check your heart rate to determine if you are running too quickly (or too slowly).
1 – 2 Day Recovery
A long run should require 1 – 2 days of recovery. Appropriate physiological responses include stiffness, mild soreness, and a general sense of fatigue or hunger for 1 – 2 days following the long run. On Day 3 a runner should be ready for his or her next quality effort.
Comfortably Hard Finish
The end of the long run should not feel like the final few miles of a marathon. Instead, the pace should feel comfortably hard, and you should be able to increase the pace by 15 – 30 seconds per mile, if necessary.
Finally, during a long run an athlete should be able to hold a conversation. If all that you can muster is a series of short grunts, you are running too fast. On the other hand, if you are able to sing your favorite song during the effort, you are running too slowly and should pick up the pace.
Inappropriate Levels of Fatigue Following a Long Run
Listed here are signs that you are completing your long run at too intense of an effort.
3+ Recovery Days
If soreness, fatigue, and low motivation persist 2 or more days following a long run, chances are that you are running too hard during these efforts.
If you struggle with motivation and find yourself dreading your long run each week, you should consider decreasing the effort of your long efforts. A long run should be comfortably hard, not an effort that requires a pre-run pep talk.
If you finish a long run and require a nap in excess of 90 minutes, you are likely running too hard.
Hitting the Wall
“Hitting the wall” or “bonking” during a long effort is a sure sign that you are experiencing inappropriate levels of fatigue. If your fueling strategy is not to blame (you should be consuming 20 – 60 grams of carbohydrates per hour of running), you could be running too fast.
Lactic Acid Build Up
A sure sign you are running too hard is if your legs and lungs burn at the end of your long run. Instead, your legs should feel as if they are tired, but not ready to collapse.
Post-Run Weight Gain
If you step on a scale after your long run and notice that your body weight increases by 1 – 2 lbs, you are experiencing signs of inflammation. If this phenomenon occurs frequently, you should decrease your long run pace or find an easier route.
Ultimately, running too hard during a long run is counter-productive and can lead to overtraining syndrome, burn out, and poor athletic performance. By reining in your effort you will be better prepared on race day to let loose and fly to the finish. Always listen to your body and approach progress gradually. Never put all your eggs in the same basket. You should be cautious especially after long runs – which take a toll on your body.
1. Van der Wall, E. E. (2014). Long-distance running: running for a long life? Netherlands Heart Journal, 22(3), 89–90. http://doi.org/10.1007/s12471-014-0521-4 Link
2. Daniels, J. T., Yarbrough, R. A., & Foster, C. (1978). Changes in $$\dot V$$ O2 max and running performance with training. European Journal of Applied Physiology and Occupational Physiology, 39(4), 249-254. doi:10.1007/bf00421448 Link
3. Metabolic Adaptation to Prolonged Physical Exercise. (1975). doi:10.1007/978-3-0348-5523-5 Link
4. Terjung RL, Baldwin KM, Mole PA, Klinkerfuss GH, Holloszy JO. Effect of running to exhaustion on skeletal muscle mitochondria: a biochemical study. Am J Physiol 223: 549–554, 1972. Link
5. Tsintzas, K., & Williams, C. (1998). Human Muscle Glycogen Metabolism During Exercise. Sports Medicine, 25(1), 7-23. doi:10.2165/00007256-199825010-00002 Link