How To Build Running Endurance – 7 Science-Proven Methods

Running is a great sport and is one of the most accessible ways to exercise. Regardless, whether I’m traveling and exploring a new place or am having an incredibly busy day, there’s always time for a run. To me, it provides freedom to explore the world (external and internal) through a very unique lens. For example, I can be running a marathon in a new city and soaking in the experience. Or I can be running a trail near my house and using the time to reconnect with myself. The question remains, though, how to build running endurance and start enjoying it?

Building stamina for running can be a daunting task, especially when you’re just getting started. That vision of running on the beach somewhere in Bali or completing your first marathon is right there. But so is the realization of the gap to where you are now.

It is true, aerobic endurance training requires structure, dedication and, most importantly, consistency. But getting to a place where you can enjoy a run can be surprisingly quick. In fact, in just a few months of training with me people find their running improving at almost no additional effort. And in this post I’ll share a few tips how to improve running endurance and structure your aerobic endurance training.

The science behind aerobic endurance training

Before we dive into what are the best endurance building exercises, let’s take a little detour into the exercise physiology. What does it actually take to improve running stamina and speed? To answer that, let’s see what happens in our body when we’re exercising.

Our muscles are made up of two types of fibers – slow-twitch (type I) and fast-twitch (type II). It is well-known that good endurance athletes tend to have a higher share of slow-twitch fibers, whereas those who are better at sprint events – higher share of fast-twitch muscle fibers.

Unfortunately, in reality it is a little more complicated than that, as fast-twitch fibers are further split into fast oxidative / glycolytic (FOG) and fast glycolytic (FG) fibres.

Properties	Type I	Type IIa	Type IIx
Motor Unit Type	Slow Oxidative (SO)	Fast Oxidative/Glycolictic (FOG)	Fast Glycolictic (FG)
Fibre type	Slow-twitch	Fast-twitch	Fast-twitch
Glycogen content	Low	High	High
Contraction speed	Slow	Fast	Fast
Contraction force	Small	Medium	Large
Fatigue resistance	High	High	Low
Capillary density	High	Intermediate	Low
Myoglobin	High	High	Low
Mitochondria	High	High	Low

How slow-twitch and fast-twitch muscle fibres affect running endurance?

Type I muscle fibers are also known as slow oxidative (SO) fibers. They operate aerobically (utilize oxygen and fat to produce energy). And while they are smaller in size and produce less force, they contain more mitochondria and myoglobin, as well as are surrounded by more capillaries, which makes them very resistant to fatigue. Imagine going for a hike or standing at a concert for a few hours – such efforts are powered primarily by these muscle fibers.

Type II muscle fibers are larger in size, are able to contract faster and produce greater force, but for much shorter duration than slow-twitch muscle fibers (fatigue quicker). These are further divided into:

• Type IIa fibers are called Fast Oxidative / Glycolytic (or FOG) fibers, because they possess characteristics of both Type I and Type IIx fibers. With relevant training these can be adapted for either short or long duration events. Physiologically, type IIa fibers are able to use both aerobic and anaerobic energy systems, which makes them fatigue much slower than type IIx.
• Type IIx fibers (also known as Fast Glycolictic or FG) produce the most force, but are the least efficient. They operate anaerobically and fatigue quickly. Type IIx fibers are used for activities of very short duration that require significant power and strength, like power lifting or 100-metre sprints.

So, physiologically speaking, the best way to build endurance for running is to develop strength in your slow-twitch muscle fibers (Type I) and grow mitochondria in your intermediate (Type IIa) muscle fibers. Interested in how to build running endurance? Continue reading to learn more.

Endurance training benefits and adaptations

The current world record for the distance covered in 24 hours is ~309.4km. That’s a pace of just under 4:40min/km (or an equivalent of seven back-to-back marathons each done in 3 hours and 16 minutes). At the same time, world record for a half marathon currently stands at 57 minutes and 31 seconds. That’s a pace of 2:43min/km maintained for almost an hour.

What does this tell us?

Slow-twitch fibers can produce power to maintain a 4:40min/km pace and fast-twitch fibers can resist fatigue while maintaining a 2:43min/km pace for close to an hour.

Most skeletal muscles in a human body contain all three fibre types. However, the proportion of type I, type IIa and type IIx fibers will vary from person to person depending on multitude of factors, including training, age and even genetics. For example, the share of slow-twitch fibers in the quadriceps femoris muscles can vary from under 20% (top level sprinters) to as high as 95% (elite marathoners).

The strength and proportion of those fibers can be impacted by training. And, in particular, when we talk about aerobic endurance training, we are looking for two specific effects. First, to develop the power that slow-twitch muscle fibers can produce which I covered in another post. And second, to ‘convert’ type IIa fast-twitch muscle fibers to adopt slow-twitch muscle fibre capabilities – high mitochondrial density, broad capillary network and so on.

Aerobic base & the role of mitochondria in building running stamina

Building stamina for running (any distance) starts with improving the effectiveness of the aerobic energy system. And, in particular, growing mitochondria in fast-twitch type IIa muscle fibers.

Mitochondria are small organelles that act as ‘powerhouses’ by taking the energy we receive from food and converting it into energy the cells can use (ATP). The more of them we have in muscle tissues (higher mitochondrial density) the more effective those tissues are at using oxygen to generate energy. Or, in other words, muscles become more resistant to fatigue.

While physical activity increases the mitochondrial content in the muscles, it’s important to note that mitochondria multiply in response to mild stress. Anaerobic training slows down that effect, as it increases the concentration of positively charged hydrogen ions (H+) in the muscles and puts extra load on mitochondria to eliminate them.

Training until exhaustion ‘overloads’ aerobic energy system and undermines endurance improvements.

Based on the above, to effectively grow mitochondria and build running endurance athletes need to keep the amount of H+ concentration in the muscles relatively low, while at the same time ensuring that plenty of oxygen is available to eliminate it. This can be achieved by training just a little outside the comfort zone. Running a little longer than the body is used to or avoiding complete exhaustion during faster intervals.

Read also: 4 Top Benefits Of Aerobic Base Training For Marathon Runners

Aerobic capacity (VO2max) and it’s impact on running endurance

In order to fully answer the question how to improve running stamina there’s one more factor to consider – aerobic capacity. Or, in other words, how much oxygen our body is able to consume.

When we exercise, we breathe in oxygen which is transferred via lungs to our blood vessels. Oxygenated blood then travels to the heart that directs it into cells. There oxygen is used to to create adenosine triphosphate (ATP) and fuel – among other things – muscle contraction.

In essence, aerobic capacity is the same as VO2max. It’s the maximum volume of oxygen the body can consume at maximum intensity in a given amount of time. It’s typically measured in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min). The more oxygen the body is able to consume the more energy it has and the longer it takes fatigue to accumulate.

VO2max is often considered as a quantitative measure of endurance fitness.

Aerobic capacity improves when we challenge our aerobic energy system. Not to our physiological limit (i.e. all-out sprint), but rather to the point when anaerobic energy system takes over and lactate starts to accumulate exponentially. VO2max is the pace that an athlete can maintain over a 10-15min all-out effort.

Fast running results in deeper and more rapid breathing, which over time makes respiratory muscles more effective. As a result, more oxygen is available for the body. But besides that targeted high intensity training improves oxygen transport and absorption capabilities thanks to – among others – better capillary density, as well as higher haemoglobin & myoglobin levels. However, such intense training should come on top of a solid aerobic base. This way the body will be able to process more training load (utilize more hydrogen) and improve more.

How long does it take to build endurance?

This is a good question. As you can imagine, physiological changes take time to materialize. Improving running endurance is not an overnight thing, but rather a growth journey. Definitely not a ‘zero to hero’ kind of thing.

In my experience, it takes 20-30 hours of consistent exercise to develop aerobic base that would provide significant change. And while accumulating that volume can take weeks and even months, first signs of improved running stamina can be visible already after half that time.

7 Methods how to improve running stamina and speed

Now that we have some context, let’s go from theory to practice.

As I shared above, the key to aerobic endurance training is to avoid getting your muscles to the point of exhaustion. While that provides some training benefit, it’s not the most effective way how to improve running endurance. Mainly due to extensive recovery time that is needed afterwards.

Instead, majority of training (80% and more) should be easy and only until mild fatigue. You should finish feeling you could have done more and able to train the next day. Listen to your body and give it enough time to recover to see consistent gains. Ideally, every one-two weeks.

#1 Classic endurance building workout – the long run

High volume low intensity (HVLI) type of training is one of the most effective exercises to increase running speed and stamina. And the most popular as well – you’ll find a weekly long run in virtually any running plan to build endurance.

When we train for an extended period of time we progressively engage more muscle fibers as the body fatigues. In response to that, our body adapts by growing more mitochondria, building capillary network, improving fat oxidation and developing strength. All of this ultimately postpones muscle exhaustion and results in a more ‘comfortable’ run. Or faster pace.

Only the fibers recruited during the exercise get the training effect.

For example, if and athlete starts to experience first signs of fatigue 1 hour into the run, that’s a signal that many slow-twitch muscle fibers are at their endurance limit. The body will start engaging fast-twitch muscle fibers more and that is when an endurance training effect starts to occur. There’s no need to run much longer than that only to ‘hit the distance’ – that particular training session served its purpose.

There can be an opposite scenario when an athlete can comfortably cover 1:30h and even 2:00h run without experiencing much fatigue. That is a signal that in order to continue improving running stamina that athlete needs to vary the long run to engage more muscle fibers.

How to: include one long easy run every week and focus on maximizing the time you spend in Zone 2. Start by going for a 40-minute run and gradually increase the time until you can comfortably run 1:30 to 2:00 hours.

#2 Boost stamina for running with short sprints

While long runs are effective at building running endurance, they don’t provide much additional training stimulus for experienced athletes. It is also quite time-consuming and stressful on the joints, so even elite runners include only one or two runs per week that exceed 1:30 hours.

There are other exercises to increase running speed and stamina, though. Sprinting is a good example. In particular, there has been interesting research done by Russian exercise physiologist Viktor Seluyanov on the process of building mitochondria in fast twitch type IIa muscle fibers. His training methodology is very effective and, in a nutshell, includes performing short but very high intensity work followed by long rest period to ensure no fatigue (H+) is accumulated.

What’s great about this approach is that sprinting activates nearly 100% of muscle fibers. Paired with long recovery interval it creates good conditions for mitochondria growth and results in substantial improvements in muscle economy in quite a short period of time.

How to: include series of very short (8-12 seconds or up to 30 steps) but hard sprints (close to maximum speed) throughout an easy session (short one to start with). Aim to complete 10-20 sprints during a session and ensure plenty of recovery in between. For example, start by including 2 to 3 rounds of 5 x [10sec Z5 + 50sec Z1] with a 5-minute Zone 2 run in between the rounds. Such session will be a great way how to improve running stamina in 2 weeks.

#3 Improve fat oxidation with short & easy fasted workouts

Fasting is the process of full or partial abstinence from food (and sometimes even water) for a period of time. Usually, 10 hours and more. When in a fasted state, the body switches its fuel source from glucose and stored glycogen to fatty acids (goes into ketosis) and research suggests that it improves mitochondrial function.

Fasted sessions have long been used to improve fat oxidation in endurance athletes – the body’s ability to utilize fat for fuel. The better level of fat oxidation an athlete has the faster (and longer) he or she can run without accumulating lactate.

How to: as we wake up our body has been typically fasting for 8-10 hours already, so this is the perfect time to execute this kind of training. If you’re new to fasting or glycogen-restricted training, start with one or two easy 20-30min run sessions first thing in the morning. Drink a glass of water beforehand and keep the intensity entirely in Zones 1/2. Once you feel comfortable with the process, increase the duration gradually week-over-week until you reach ~1hour.

#4 Build running stamina with tempo training

Tempo is a ‘comfortably uncomfortable’ effort. You feel like you’re exercising, but you can still carry on for quite some time and even kind of maintain a conversation. Or at least spit out a sentence before gasping for air.

An athlete should be able to hold tempo effort for at least 3-4 hours. And while it might seem as a good workout, many athletes tend to overuse this intensity. Training every day at moderate intensity is a sure-fire way to physical or emotional burnout, or training plateau. However, tempo sessions do provide strong aerobic stimulus for experienced athletes who use this intensity carefully and strategically. It engages more muscle fibers, thereby growing mitochondria in them and also has a positive impact on aerobic capacity.

How to: include a continuous run in low- to mid-Zone 3 (30 to 60 minutes) once a week. This will be a form of speedwork, so consider it a key session. Don’t get too concerned about the pace during this endurance building workout. The purpose is to challenge the aerobic energy system a little more than a typical easy run would. So, try to relax and listen to your body.

Read also: How To Use Polarized Training Model To Break Through Workout Plateau

#5 Improve aerobic capacity with aerobic fartleks

Fartlek translates from Swedish as “speed play”. It is a continuous session during which you mix segments of faster, harder efforts with slower, easier ones. In a fartlek fast surges are immediately followed by a certain number of minutes at easy pace. This cycle repeats itself and by the end of the session you will have gathered a considerable amount of time at quality effort.

A fartlek is designed to provide a strong aerobic stimulus, so you should never go above threshold effort on any given “fast” surge. This session challenges aerobic energy system and significantly improves aerobic capacity, because the heart rate will stay elevated throughout the entire workout.

If running is too hard for you (or if your easy pace is rather slow), try a run-walk approach instead. Walking does help to build running endurance and this is a great workout to incorporate it.

How to: During this session perform faster (mid-Zone 4) surges, that are immediately followed by easy or tempo effort. For example, sets of 30sec hard / 90sec easy or 1min hard / 1min easy. Don’t get too concerned about the pace during this workout – the purpose is to tune in with your body and learn how different efforts feel.

#6 Don’t forget about explosive strength training for runners

Not all endurance building exercises have to be run sessions. We can apply the same principles to strength training as well. Often, stamina-building training effect can be accomplished in as little as 15 minutes of work.

Runners in particular, will benefit the most from the so-called explosive strength training – moving the weight as fast as possible through the entire range of motion. The keyword is explosiveness – movements should be powerful, quick and with perfect technique. The force you apply should be greater than is required to move the load. Just like sprinting, this type of training engages more muscle fibers, thereby stimulating the growth of mitochondria in them.

How to: the focus of this sessions should be on prime movers (large muscle groups). Select 2-3 main exercises that engage the most muscle groups throughout the body (for example, power clean and deadlift) and perform them explosively. The protocol is 2-3 sets of 5-6 repetitions with the 30%-50% load (of your estimated 1-repetition maximum) for each exercise. In between sets take 3-5 minutes of rest. You can add 1-2 supportive exercises on small or stabilizing muscle groups as long as they don’t interfere with recovery. If you can no longer perform the exercise explosively, you should stop (even if the set is not completed).

Read also: 12 Effective Strength Building Workouts For Any Experience Level

#7 Include plyometric exercises for runners

Plyometrics are quick, powerful movements repeated in quick succession. It’s another non-running session that can help build running endurance.

Studies show that plyometric training can significantly contribute to running performance. In particular, explosives jump engage a lot of muscle fibers and, much like strength training, stimulate mitochondria growth in them. That results in greater efficiency, but also as – a side benefit – increases the stride length (faster speed) and the foot joint resilience (less injury risk).

An athlete who wants to run longer and faster needs to jump more and higher.

How to: If you’re new to plyometrics, start with 2 simple jumps – single leg hops and deep stair hops – and do each of them explosively for ~20seconds. You can repeat each jump after a 1-3min rest or if you’re an advanced athlete organize a session in a form of Tabata (i.e. 20sec of intense jumping followed by 10sec rest). Keep in mind that the movements should be explosive and, therefore, very taxing. So, keep the number jumps and repetitions low.

Sample week of aerobic endurance exercises

As you see, simply running more is not the most efficient way how to build running endurance. You won’t find any elite athlete who goes out and runs aimlessly every day for as long as he or she can. Instead, they are mixing it up quite a lot with very specific training sessions. And now so can you.

There are multiple ways you can organize your running plan to build endurance. As long as you’re consistent and focus on not pushing yourself to the point of muscle exhaustion, you’ll see progress. But by far the best way how to build endurance for running is to combine the methods.

Below I’ve prepared a sample week of aerobic endurance training for you to use to begin building endurance. 4/5 days of training with 2 days off – try it out.

Day	Training
Monday	Off
Tuesday	Aerobic fartlek
Wednesday	Easy run (am) + explosive strength (pm)
Thursday	off
Friday	Easy with 10-20 sprints
Saturday	Fasted Zone 1/2 or cross-training
Sunday	Long easy