You’ve finally committed to following a real training plan, not just winging it with aimless jogs around the neighborhood. But when you open that carefully downloaded PDF, you’re greeted with phrases like “fartlek,” “negative splits,” and “recovery run.” Your first thought: Did I accidentally download a document in Swedish?
For new runners, the training jargon can feel like a secret language designed to keep outsiders at bay. But understanding a handful of key terms can transform your workouts from bewildering to empowering—and might just help you run faster and stay healthier.
Here are five of the most confusing running training terms, explained in plain English.
1. Fartlek
Let’s start with the weirdest word in running: fartlek. Yes, it sounds like something a middle schooler would giggle about, but it’s actually a Swedish term meaning “speed play.” Think of it as structured chaos for your legs.
A fartlek run involves varying your pace throughout a workout—sprinting to one landmark, jogging to the next, then picking up the pace again whenever the spirit moves you. Unlike traditional interval training where you run, say, four 800-meter repeats at a specific pace with exact recovery times, fartlek is much looser and more spontaneous.
You might sprint to that red mailbox, jog easy until you reach the stop sign, then run at a moderate pace for two minutes before easing back. The beauty is in the flexibility: you’re in charge of when to push and when to recover, making it perfect for days when a structured track workout feels too rigid or when you’re running on trails where precise pacing is impossible.
“Fartlek training teaches runners to tune into their bodies and learn when they can push harder and when they need to back off,” says Dr. Bryan Saltzman, a sports medicine specialist at IU Health in Indianapolis and team physician for the IU Indianapolis Jaguars. “It’s particularly valuable because it mimics the unpredictable pace changes you’ll experience in an actual race.”
The Swedes knew what they were doing when they invented this one.
2. Tempo Run
If fartlek is freestyle jazz, a tempo run is classical music—structured, sustained, and seriously effective. A tempo run means holding a “comfortably hard” pace for an extended period, typically 20 to 40 minutes for most recreational runners.
The sweet spot is about 80-90% of your maximum heart rate, or roughly the pace you could sustain for an hour if you were racing. You should be breathing heavily enough that you can only manage a few words at a time, not full sentences, but you shouldn’t feel like you’re sprinting for your life either.
The magic of tempo runs lies in what they do to your lactate threshold—the point where your muscles start accumulating lactate faster than your body can clear it. By training right at or slightly below this threshold, you gradually push it higher, meaning you can run faster before that burning, heavy-legged sensation kicks in.
For beginners, the phrase “comfortably hard” can feel like an oxymoron. Start conservatively: try 10 minutes at tempo pace sandwiched between a 10-minute warm-up and cool-down. As you get stronger, extend the tempo portion. Your future racing self will thank you.
3. Recovery Run
Here’s a term that seems self-explanatory but trips up countless runners: the recovery run. It’s not just an easy run—it’s deliberately, almost painfully slow.
A recovery run is typically done within 24 hours after a hard workout or long run. The purpose isn’t to build fitness or log impressive paces; it’s to gently move your legs, increase blood flow to tired muscles, and facilitate the repair process without adding stress.
Think of it as active recovery. Your pace should be slow enough that you could hold a full conversation without getting winded. If you’re checking your watch and feeling embarrassed by the numbers, you’re probably doing it right. Many coaches suggest running 60-70% of your maximum heart rate—some even advocate going slower.
The confusion often comes from the name itself. Recovery runs don’t actually make you recover faster than a complete rest day would; they simply allow you to add mileage without accumulating fatigue. If you’re feeling especially sore or exhausted, a rest day is still the better choice.
The cardinal sin? Turning recovery runs into “easy-ish” runs. Once you start pushing the pace, you’re no longer recovering—you’re just adding more stress when your body needs a break.
4. Cadence
Cadence is the number of steps you take per minute while running, often abbreviated as SPM (steps per minute). For years, the running world treated 180 SPM like gospel—the magical number all runners should target, based on observations of elite marathoners in the 1980s.
Turns out, that 180 figure isn’t quite the universal truth it was made out to be. Most recreational runners naturally fall somewhere between 160 and 180 SPM, and that’s perfectly fine. Taller runners often have slightly lower cadences; shorter runners trend higher. Your pace matters too—faster running naturally increases step rate.
So why does cadence matter at all? A higher cadence with shorter strides typically reduces the impact forces on your joints and helps prevent overstriding—that awkward moment when your foot lands way out in front of your body, essentially putting on the brakes with every step.
If you’re curious about your own cadence, count how many times one foot hits the ground in 30 seconds, then multiply by four. Or, more realistically, just check your running watch, which almost certainly tracks it automatically these days. If you’re consistently below 160, you might benefit from consciously shortening your stride and quickening your turnover.
5. Negative Splits
Negative splits sound like a gymnastics move gone wrong, but they’re actually a pacing strategy that can make the difference between a triumphant finish and a death march through the final miles of a race.
To run negative splits means to run the second half of your race faster than the first half. In a 10K, for instance, you might run the first 5K in 23 minutes and the second 5K in 22 minutes. Counterintuitive as it seems, starting slower and finishing faster often produces better overall times than charging out of the gate.
Why? Starting too fast depletes your glycogen stores—your body’s premium fuel—and causes lactate to accumulate early, leaving you struggling to maintain pace when it matters most. A conservative early pace preserves energy, allows for better pacing control, and sets you up to feel strong when others are fading.
Some of the greatest marathon performances in history have followed a negative split strategy. The late Kelvin Kiptum ran negative splits when he set the marathon world record of 2:00:35 at the 2023 Chicago Marathon, finishing strong while others wilted.
The hardest part? Actually doing it. Race-day adrenaline makes it incredibly tempting to sprint off the starting line with everyone else. It takes discipline to hold back early, trust your training, and save your energy for when you’ll need it most. Practice negative splits during training runs—start easy and finish fast—so your body learns the rhythm before race day arrives.
The running world has its own peculiar language, but each term exists for a reason—usually to help you train smarter and race faster. You don’t need to memorize every piece of jargon before lacing up your shoes, but understanding these five basics will make those training plans a lot less intimidating.
And remember: even elite runners were once beginners trying to figure out what the heck a fartlek was. You’re in good company.