Fartlek, bonking, DNF, negative split… it can all seem like another language, especially if you are new to running. We explore some of the stranger running slang terms and what they actually mean so that you can at least try and sound interested or informed when it goes all geek speak. 


No – it’s not what you think. Bonking in a race means to hit the wall – another term that may confuse but essentially it’s when your body just feels like it can’t go any further. When you are completely depleted of carbs and you just can’t carry on. This can happen at around 18-20 miles of a marathon. The way to avoid this is to take on plenty of fuel earlier on in the race to keep your glycogen levels topped up.


In running, cadence refers to the number of times your feet hit the ground per minute. A higher cadence is generally considered to be better for running form and efficiency, as it helps to keep your stride short and your feet under your centre of gravity. Cadence can be improved through training, and there are a number of tools and techniques that can help runners to increase their cadence.


Once you have had it, it needs no introduction! Chafing is a common skin irritation that occurs when two surfaces rub together repeatedly. It can be caused by a number of factors, including:

  • Sweat: Sweat can make the skin more susceptible to chafing.
  • Friction: Friction can also cause chafing. This can happen when you are wearing clothing that is too tight or when you are doing activities that involve a lot of movement.
  • Moisture: Moisture can also contribute to chafing. This can happen when you are sweating or when you are in a humid environment.
  • Irritants: Chafing can also be caused by irritants, such as detergents or soaps.


When a male runner gets overtaken by a female runner in a race.

Chub Rub

The unfortunate result of one’s thighs rubbing together and chafing.


Did not finish / did not start. You often see this term on race results for this participants who just didn’t make it to the end or, maybe worse, the start line. I think I’ve had one DNF in my running history. It was a 30 miler 2 weeks after a 50 and it just wasn’t pretty. At 14 miles I decided that I was bored of running that day and called someone to pick me up. I went home and sulked for a week swearing to never run another ultra. Then I went out and did a 56 miler.


Another name given to the soul-less device that is the treadmill.

Elevation Gain / Vert

The amount of ascent achieved during a run or hike.


Fartlek is a Swedish word that means “speed play.” It is a type of interval training that involves varying your pace throughout your run, alternating between fast segments and slow jogs.

Fartlek workouts are a great way to add some variety and fun to your running training. This type of speed work can also boost your performance, increase your cardiovascular output, and allow you to run at higher intensities for longer periods.

Here are some tips for doing fartlek workouts:

  • Start with a warm-up. A 10-minute warm-up will help to get your body ready for the workout.
  • Choose a route that has a variety of terrain. This will help you to vary your pace and intensity.
  • Set some landmarks. These can be anything from lampposts to trees to buildings.
  • Use the landmarks to guide your pace. When you reach a landmark, accelerate to a faster pace. When you pass the landmark, slow down to a jog.
  • Listen to your body. Don’t push yourself too hard. If you feel tired, slow down or take a break.
  • Cool down after your workout. A 10-minute cool-down will help your body to recover from the workout.

Fell Running

Fell running is a type of trail running that is typically done on rough, mountainous terrain. A popular sport in the United Kingdom, where it originated in the Lake District. Fell runners often compete in races that are over 10 miles long and involve significant elevation gain. It requires a high level of fitness and agility, as runners must be able to navigate uneven terrain and climb steep hills.


Glycogen is a polysaccharide that serves as the body’s main source of stored energy. It is made up of glucose molecules, which are linked together in a chain. Glycogen is stored in the liver and muscles, and it can be quickly broken down to release glucose into the bloodstream when needed for energy.

The amount of glycogen that can be stored in the body is limited. The liver can store about 100 grams of glycogen, and the muscles can store about 400–500 grams. Once these stores are depleted, the body will start to break down muscle tissue for energy. Good levels are important for maintaining blood sugar levels and providing energy for physical activity. It is also important for the brain, which relies on glucose for energy.


Goal marathon pace or target marathon pace. When you are training for a marathon and run sections of your run, or the entire run, at your intended/expected pace.

LT (get ready for the science)

The lactate threshold is the point at which lactate (lactic acid) begins to accumulate in the blood at a faster rate than it can be removed. This happens when you are exercising at a high enough intensity that your body cannot rely on aerobic metabolism to produce energy, and instead has to switch to anaerobic metabolism.

It is an important concept for runners because it is the point at which you can no longer maintain a steady pace. If you try to run faster than your lactate threshold, you will eventually slow down or have to stop.

There are a few different ways to measure your lactate threshold. One way is to do a lactate threshold test, which involves running on a treadmill or track while having blood drawn from your finger at regular intervals. The blood samples are then analysed to determine the lactate concentration. Another way to estimate your lactate threshold is to use a heart rate monitor. Your lactate threshold heart rate is the highest heart rate that you can maintain for an extended period of time without accumulating lactate in the blood.

Once you know your lactate threshold, you can use it to plan your training. Tempo runs and interval workouts are two types of workouts that are designed to improve your lactate threshold. Tempo runs are done at a pace that is just below your lactate threshold, while interval workouts involve alternating between short bursts of high-intensity running and periods of rest or easy running.

Naked Running

No, not going on a run with no clothes on – that would get you arrested. It does actually mean running without a watch/activity tracker.


When the foot rolls inward after hitting the ground.


Personal best or personal record – running a race, distance or course faster than you have run it before.

Plantar Fasciitis

What is this strange language of which you speak? If you have heard the term we hope it’s not because you have it. It is a pain in the bottom of the heel. It is caused by inflammation of the plantar fascia, a thick band of tissue that runs along the bottom of the foot from the heel to the toes.

The plantar fascia helps to support the arch of the foot and absorb shock when you walk or run. When the plantar fascia becomes inflamed, it can cause pain in the heel that is worse when you first get up in the morning or after sitting for a long time.

Race Bandit

Someone who runs the race without an official entry.

Rest Days

This is such a tricky one that most runners don’t even know what this means. It is in fact, probably the strangest term you will hear! A rest day is when you actually don’t run and you actually take a day off to let your body recover!


Running induced hunger – basically – you go for a run then are starving and want to eat everything in sight. Fight the urge to fill up on crap and eat sensibly. Perhaps have a banana handy for after your run or fuel properly prior to running. 

Negative Splits – Ever heard this one and just nodded and pretended you know what it means? A negative split is when you run the second half of a race faster than the first and largely something that only the experienced can master and not those that go off like a race horse at the start only to end up regretting it about 3 miles in!  


Haha – we know a few of these. Massively playing down your ability and convincing everyone that you are slower than what you are then pulling it out of the bag during a race and acting all surprised. Alternatively, doing all your reps at a set pace and then going off full steam on the last one proving that you didn’t actually put in all you had for the rest of the session. 

Snot Rocket

Pass me a bucket! This is the disgusting art of blowing your nose mid run without tissue and involves pressing down on one nostril and blowing out of the other. Don’t do it – it’s gross. 


Tapering is a period of reduced training in the weeks leading up to a race. It allows your body to rest and recover, and it can help you to perform your best on race day.

There is no one-size-fits-all tapering plan, as the best approach will vary depending on your individual fitness level and race goals. However, there are some general guidelines that can help you to create a tapering plan that is right for you.


When the ankle rolls less than 15% inward when running.