Long Run Training: Optimal Pace, Distance & Timing

Many runners want to add long runs to their training but aren’t sure how fast to run or how far to go.

This article explores how to maximize the benefits of long run training. We’ll also examine the physiological adaptations from an exercise science perspective.

Two of the most influential training frameworks in marathon running — Jack Daniels’ Running Formula and Arthur Lydiard’s running method — both recommend at least one long run per week.

Elite runners almost universally include long runs as a cornerstone of their training.

By the end of this article, you’ll have a clear understanding of the right distance, pace, and timing for your long runs.

What Is a Long Run? Terminology and Definitions

In Jack Daniels’ Running Formula, this workout is called an “L run” (Long run). Arthur Lydiard refers to it as an “aerobic long run.” It’s also commonly known as a “long jog.”

Some coaches and books distinguish between terms based on pace. “Long jog” refers to running a long distance at a gentle jogging pace, while “long run” implies a somewhat faster effort.

For clarity, here are the definitions used in this article:

※ Easy pace refers to the conversational pace in Jack Daniels’ Running Formula.

In this article, “long run” is used as a general term for any continuous training run covering a long distance.

LSD (Long Slow Distance) is sometimes used interchangeably with long run, but the two are fundamentally different. LSD means running a long distance at a pace that feels truly slow to you.

Long run training, as defined here, is always run at Easy pace or faster.

Benefits of Long Run Training

Understanding the benefits of long run training starts with choosing the right pace. Once you know what you’re trying to achieve, the appropriate pace becomes clear.

Physiological Benefits of Running at Easy Pace

The physiological benefits of long runs vary depending on pace. When you run at Easy pace, the adaptations are similar to those gained from regular jogging.

These include improved injury resilience, cardiac muscle development, angiogenesis, adaptations in working muscles, and an increase in mitochondrial density and function.

The following article covers the full range of benefits from Easy pace training:

How to Build Race-Specific Fitness Through Long Runs

Beyond basic physiological adaptations, the key benefit of long runs is building race specificity — particularly for the half marathon and full marathon.

Race specificity, in practical terms, means training your body to keep moving even as muscle glycogen runs low.

In the full marathon, the infamous “30K wall” is well known. It occurs when muscular endurance declines and muscle glycogen depletion makes it increasingly difficult to maintain your pace.

The race-specific adaptations gained through long run training include the following:

In a marathon, you will always reach a point in the second half where muscle glycogen drops significantly. Consistently running long distances teaches your body that it can keep going — building both physical resilience and mental confidence for the late stages of a race.

Prolonged exercise gradually lowers blood sugar levels. When blood sugar drops below a certain threshold, glucose supply to the muscle fibers becomes restricted — and you hit a state known as bonking, where your legs simply refuse to move.

Consistent long run training improves mitochondrial density and fat utilization. Hansen et al. (2005)※1 showed that training in a glycogen-depleted state promotes endurance adaptations in skeletal muscle.

As fat utilization improves, your body relies less on glycogen at the same pace — meaning more glycogen is preserved for the final miles of your race.

Long-term accumulation of mileage also improves running economy — the energy cost of running at a given speed. Barnes & Kilding (2015)※2 found in their review that accumulated training volume and running history are the primary drivers of running economy improvements.

Better running economy means lower energy expenditure at the same pace, which also helps preserve muscle glycogen through the later stages of a race.

This is not unique to long runs — consistent endurance training in general increases the number and function of mitochondria, gradually enhancing fat utilization. De Bock et al. (2008)※3 experimentally demonstrated that endurance training significantly increases fat oxidation-related proteins in skeletal muscle (FABP and CPT1).

Long Run Pace: Finding the Right Intensity

Let’s break down the recommended pace range for long runs.

Aim for Easy to Moderate Pace

The recommended pace range for long runs is Easy to Moderate pace. For a full breakdown of each intensity level, see the articles below:

Easy to Moderate pace is relaxed, but it’s not slow. For long runs to be effective for marathon training, going too slowly is counterproductive.

Some training methods recommend LSD (Long Slow Distance), but in my view, this approach is less likely to translate into improved marathon performance.

On the other end, running your long runs too fast is equally problematic. Consistently pushing close to marathon pace puts excessive stress on the body, increases injury risk, and makes it difficult to maintain training over the long term.

The key is to train at an intensity that allows adequate recovery, so you can continue building mileage consistently.

Increasing Pace as Your Race Approaches

As your marathon approaches, it’s important to gradually bring your long run pace closer to race pace. We discussed earlier how race specificity is one of the primary goals of long run training.

The closer your training pace is to race pace, the greater the specificity — and the greater the training benefit. So, within sustainable limits, push your long run pace toward your goal marathon pace in the weeks leading up to the race.

How Far Should Your Long Run Be? Keep It Under 25–30% of Weekly Mileage

Long runs are highly effective, but to avoid overloading your body, it’s important to set a cap on how far you run in a single session.

Set a Distance Cap for Injury Prevention

Jack Daniels’ Running Formula recommends placing a cap on the distance of each long run.

Your long run distance cap depends on your typical weekly volume. If you run 50km (31 miles) per week, your long run cap is 15km (9.3 miles). At 100km (62 miles) per week, the recommended cap is 25km (15.5 miles).

Running a 30km (18.6 mile) long run consistently requires a weekly mileage base of 120km (75 miles) or more.

The purpose of this cap is to prevent excessive physical stress from any single session. Overdoing it slows recovery, limits adaptation, and in the worst case leads to injury.

There are exceptions — for example, race-simulation training as your marathon approaches, or beginners training to finish their first marathon who need to build confidence over longer distances.

In those cases, proceed carefully — listen to your body and gradually find the training load you can handle without getting injured.

Outside of those exceptions, consistently keeping your long run within the recommended distance cap is the right approach.

How to Gradually Extend Your Long Run Distance

To safely extend your long run distance while minimizing injury risk, the first priority is gradually building your overall weekly mileage.

Daniels’ methodology recommends increasing weekly mileage by no more than 10% per week, and maintaining the same volume for at least 4 weeks (about one month) before increasing again.

The process is sequential: gradually increase your overall weekly mileage first, then use that higher base to justify a longer long run.

Speaking from personal injury experience, this approach to building mileage is one of the most important principles I know.

Looking back at every injury I’ve sustained, they all happened when I increased my mileage too quickly. When I hurt my knee, I was unable to run properly for nearly two to three months.

To keep training consistently and injury-free, always increase your mileage with patience and care.

Should You Run Near-Race Distance in Training?

Many runners wonder whether they should run close to the full marathon distance in training. The answer is yes — running near-race distance is acceptable.

However, doing so every week significantly increases injury risk. If you want to exceed your normal distance cap, limit it to once a month or once every three weeks to keep that risk manageable.

When to Schedule Your Long Run for Maximum Effect

Let’s look at the best timing for your long run to maximize its training benefit.

There are two approaches: scheduling the long run as a standalone structured workout, or running it as the second day of back-to-back training.

When your long run involves pushing close to marathon pace, treat it as your primary structured workout for that week — the session itself carries high training load.

On the other hand, if the long run is a secondary session, placing it the day after a hard workout can amplify its effect.

The reason: when you run long the day after a hard session that depleted muscle glycogen, you’re running in a glycogen-reduced state. This stimulates stronger mitochondrial adaptations.

Hansen et al. (2005)※1 and Yeo et al. (2008)※4 both showed that training in a glycogen-depleted state — even at the same training volume — significantly increases mitochondrial enzyme activity and fat oxidation rates compared to training when fully fueled.

That said, for recreational runners who are new to long runs, I recommend treating the long run as your primary structured workout rather than adding it on top of a hard session.

The reason is simple: if you’re not yet accustomed to running long, stacking it after a hard workout dramatically raises injury risk.

Running long in an energy-depleted state also increases protein breakdown, which delays recovery. Once you’ve built up experience and feel comfortable with long runs, you can experiment with back-to-back training.

To summarize: start with the long run as a standalone structured workout. As your fitness and experience grow, try shifting it to the day after a hard session for greater training stimulus.

Even if you’ve been running long without much thought up to now, understanding the purpose behind these sessions allows you to reconsider your pace and timing for better results.

Make your long runs count — and use them to take your marathon performance to the next level.

References

※1 Hansen AK et al. (2005) “Skeletal muscle adaptation: training twice every second day vs. training once daily” Journal of Applied Physiology

※2 Barnes KR, Kilding AE (2015) “Strategies to improve running economy” Sports Medicine

※3 De Bock K et al. (2008) “Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake” Journal of Applied Physiology

※4 Yeo WK et al. (2008) “Skeletal muscle adaptation and performance responses to once a day versus twice every second day endurance training regimens” Journal of Applied Physiology