Expert-backed ways to build speed endurance

Working to improve your lactate threshold makes more difficult paces feel less exhausting. As a result, it makes you a faster and more efficient runner.

Alex Morrow, a running coach and the founder of Resolute Running, likens the human body and its ability to flush out waste created by lactate threshold training to a bucket with a hole in the bottom. ‘As you run, waste [the lactate that you produce while running] is being thrown into that bucket,’ explains Morrow. ‘As long as you’re running at the right pace, the waste going in the bucket drains straight out the bottom and you’re fine. When you pass that lactate threshold, you put too much waste in the bucket – it then overflows and you slow down. Lactate threshold training creates a bigger bucket and a bigger hole at the bottom of that bucket.’

By building up your body’s speed endurance, you’ll also boost your self-confidence, as you’ll start to see yourself run further and further while maintaining your pace during these tough sessions. Ng says that experiencing this dose of self-confidence during a threshold workout will give you the reassurance that, come race day, you’ll be able to go out there and smash it.

The academics attest to this, too. According to an article published by the University of New Mexico, ‘lactate threshold is the most important determinant of success in endurance-related activities and events and the main goal of endurance training programs should be the improvement of this parameter’.

Your lactate threshold is the exercise intensity level at which lactate – a byproduct of intense exercise – accumulates in the blood faster than you can remove it. At its core, it’s the line between low- and high-intensity exercise.

To find your lactate threshold pace, you could invest in doing a test at a lab. But, for a more budget-friendly option, you can calculate this pace using a practical field test. To do this, complete a warm-up, then run at your best possible intensity for 30 minutes. Then, use your average running speed during that effort to calculate your ideal threshold pace.

In general, runners find their lactate threshold pace to be about a seven or eight out of 10 on the rate of perceived exertion (RPE) scale, which is an effort that is broadly described as ‘comfortably hard’. You could also describe this effort as one that you can sustain for one hour, but not longer.

The key is going at an effort you can sustain – it’s not an all-out exertion. ‘There’s something in us that makes us all want to go faster,’ says running coach Tia Accetta, who co-founded Run Tuscon. ‘But, with this lactate threshold training, don’t.’

First, it’s important to note the difference between tempo runs and lactate threshold workouts. Ng describes the term ‘tempo run’ as an overarching umbrella when discussing workouts designed for specific paces. ‘Tempo runs don’t have to be at threshold [pace],’ he explains. ‘But lactate threshold runs are one of the many types of tempo run. Under the umbrella, you can also run [tempo runs] at marathon pace, or maybe half marathon pace.’

To clear up a search process that can often become overwhelming and confusing, we’ve developed a list of versatile threshold workouts, from short repetitions to 15-plus-mile days, that help every type of runner to build their speed endurance.

5-minute interval workout

Why it works

Intervals work well for those who are new to threshold workouts, because the breaks between reps give runners time to reflect on how the previous one went and how they can adjust their pace for future reps.

Morrow also explains that many runners who are just starting to train at lactate threshold pace tend to struggle holding the pace for 20 to 30 minutes. So, he eases them into it with intervals.

The versatility of these workouts means that they benefit those training for 5K races up to marathons.

How to do it

• 15-20-minute warm-up at easy pace.
• 6 x 5 minutes at threshold pace, with 60 to 90 seconds of recovery between each rep.
• 15-20-minute cooldown at easy pace.

8-minute interval workout

Why it works

‘Breaking down tempo runs into longer, time-based intervals is a good way to practice,’ says Accetta. She adds that for 5K runners training for the shorter distance, just two of these eight-minute intervals could constitute a workout. Meanwhile, for marathon runners, four or even five eight-minute intervals at lactate threshold pace can help them to hit their desired workout.

How to do it

• 15-20-minute warm-up at easy pace.
• 2-5 x 8 minutes at threshold pace, with 60 to 90 seconds of recovery between each rep.
• 15-20-minute cooldown at easy pace.

Steady-state workout

Why it works

Once you’re comfortable with lactate threshold pace and want to sprinkle longer, more sustained efforts into your training plan, all three coaches recommend doing this steady-state tempo run. ‘It’s simple, easy and everybody loves doing it,’ says Morrow. ‘It also teaches you how to handle that low-grade discomfort, which is what distance running is all about.’

As Morrow describes, eliminating the breaks between intervals forces runners to battle through minor fatigue and stick with their comfortably-hard pace.

Ng adds that all workouts are designed to simulate parts of a whole. In this case, training your body to run at lactate threshold pace for 20 to 30 minutes teaches you how to push through those tough miles of any race.

How to do it

• 15-20-minute warm-up at easy pace.
• 20-30 minutes at threshold pace.
• 15-20-minute cooldown at easy pace.

Double-digit marathon progression

Why it works

At a quick glance, progression workouts seem daunting, considering they cover the most mileage. However, changing paces throughout a long workout can be one of the best ways to train your body to maintain a pace during the later stages of a race, says Accetta.

Bear in mind that the workout below requires you to run about 15 miles, so you definitely want to build up to this progression. It’s especially effective for experienced marathoners, as it teaches you to run through fatigue and discomfort, which are both necessary for race day. ‘It’s not always fun, but it’s extremely effective,’ says Morrow.

How to do it

• 3-4 miles at easy pace (3-4 RPE).
• 3-4 miles at marathon pace (4-5 RPE).
• 20 minutes at lactate threshold pace (7-8 RPE).
• 3-4 miles at marathon pace (4-5 RPE).
• 3-4 miles at easy pace (3-4 RPE).

9-mile marathon progression

Why it works

‘To me, this is just a really good representation of fatigued legs and getting tired, but still maintaining a threshold effort in the middle,’ says Accetta. ‘I feel like all runners, after they do it, have a good dose of confidence.’

This nine-mile workout, while employing a more gradual increase and decrease in pace than Morrow’s progression workout above, is considerably shorter in overall distance. That said, you’ll still receive the benefits of simulating mid-race fatigue while sustaining your lactate threshold pace, prepping you well for race day.

How to do it

• 1 mile at easy pace (3-4 RPE).
• 1 mile at marathon pace (4-5 RPE).
• 1 mile at half marathon pace (5-6 RPE).
• 3 miles at lactate threshold pace (7-8 RPE).
• 1 mile at half marathon pace (5-6 RPE).
• 1 mile at marathon pace (4-5 RPE).
• 1 mile at easy pace (3-4 RPE).

Hill threshold workout

Why it works

Yes, you can incorporate hills into a lactate threshold workout. Morrow says that he recommends hill repeats to runners who may want to take a step back from heavy mileage or don’t feel confident enough to tackle a full steady-state lactate threshold workout.

He reminds runners that the uphill effort should amount to the ideal 20 minutes recommended for threshold workouts. The jog back downhill is simply a break and should not be calculated into the amount of effort given.

Morrow’s threshold hill repeat workout, detailed below, has multiple benefits. It offers both the endurance gains of threshold training and the positive aspects of hill workouts, such as building leg and core strength.

Because of the hill, you don’t necessarily need to run this workout at threshold pace, but rather at threshold effort. Basically, you’ll run slower because you’re going uphill, but you’ll still aim to give the same effort that you feel during your lactate threshold workouts on flat ground.

How to do it

• 15-20-minute warm-up at easy pace.
• 10 x 2 minutes of uphill running (7-8 RPE), followed by a light jog back down the hill after each repetition.
• 15-20-minute cooldown at easy pace.

Put in a consistent effort

‘We’re always looking for that sweet spot of 20 to 30 minutes of effort,’ says Morrow. ‘Whether that’s short intervals, long intervals, it doesn’t really matter. Get those 20 to 30 minutes.’

As the weeks of training go by and your threshold pace transitions from being comfortably hard to just comfortable, that’s when you know that you’re achieving the desired result.

Keep your interval breaks short

‘The longer the break, the more likely you are to go out too fast,’ says Accetta. ‘Technically, you shouldn’t need a break if you’re keeping your conservative pace. You want to go into the next [repetition] still feeling a little bit fatigued.’

Lactate threshold training is all about maintaining your pace for a set amount of time. So, trimming your break time down so that you feel fresh but not fully recovered is essential to a quality interval workout.

Trust your legs more than your mind

Lactate threshold workouts are hard. Not hard in the sense of high-intensity effort, but hard on your mind and its perception of your body’s ability to set and maintain your comfortably hard pace.

‘Trust your legs more than your mind,’ says Ng. ‘Your mind is going to be in your way the whole time. It’s going to tell you to stop, but your job is to fight it. When that thought comes into your head, I want you to hang in there for one more minute and I guarantee that you’re going to be fine. The only time that you should stop is when your legs stop.’

Be smart about your training

Make sure that you’re putting these workouts into the correct phase of your training plan to maximise the benefits. In other words, don’t start knocking out lactate threshold workouts two weeks before your race.

Improving your lactate threshold takes time. As such, to reap the greatest reward from these workouts, Morrow suggests incorporating them once a week into the strength and endurance-building phase of your plan, or about two to four weeks into a 16-week marathon training plan.