8
- 80/20 Rule
- A training principle where roughly 80% of your running should be at an easy effort and 20% at moderate-to-hard effort. Based on research by Stephen Seiler showing this intensity distribution optimizes endurance and speed while minimizing injury risk.
A
- Active Recovery
- Very light exercise (walking, easy cycling, gentle swimming) done on a rest day to promote blood flow and recovery without adding training stress. Different from a recovery run, which is still running.
- ACWR
- Acute:Chronic Workload Ratio — compares your recent training load (last 7 days) to your longer-term average (last 28 days). A ratio between 0.8 and 1.3 is generally considered safe. Spikes above 1.5 significantly increase injury risk.
- Adaptation
- The process by which your body gets stronger and more efficient in response to training stress. Adaptation happens during rest, not during the workout itself. This is why recovery is a non-negotiable part of training.
- Aerobic Base
- The foundation of endurance fitness built through consistent easy running. A strong aerobic base allows you to run longer before fatiguing and recover faster between hard sessions. Most of your training should target this system.
- Aerobic Threshold
- The exercise intensity at which your body transitions from using primarily fat for fuel to increasingly relying on carbohydrates. Roughly corresponds to the upper end of "easy" effort — you can still hold a conversation.
- Aid Station
- A designated point along a race course where water, sports drinks, and sometimes food are available. In longer races (half marathon and up), aid stations are typically every 1-2 miles.
- Anaerobic Threshold
- The intensity at which your body produces lactate faster than it can clear it. Often used interchangeably with lactate threshold, though they're technically slightly different. Corresponds roughly to the pace you could sustain for about an hour.
B
- Base Building
- A training phase focused on gradually increasing weekly mileage at easy effort. Develops aerobic fitness, strengthens connective tissue, and builds the foundation for harder training later. Typically lasts 4-8 weeks.
- Bonk
- Running out of glycogen (stored carbohydrate) during a long run or race, causing sudden and severe fatigue. Also called "hitting the wall." Most common after 18-20 miles in a marathon if fueling is inadequate.
- BQ
- Boston Qualifier — a marathon finishing time that meets the qualifying standard for the Boston Marathon. Standards vary by age and gender. For a 30-year-old male, the current BQ is 3:00:00.
- Brick Workout
- A training session combining two disciplines back-to-back, most commonly cycling followed immediately by running. Primarily a triathlon term, but useful for any runner who cross-trains on the bike.
C
- Cadence
- Steps per minute while running. Most recreational runners are between 150-170 spm. Higher cadence (170-180+) is associated with better running economy, but forcing a specific number isn't recommended — it tends to improve naturally as fitness and speed increase.
- Carb Loading
- Increasing carbohydrate intake in the 2-3 days before a long race to maximize glycogen stores. Effective for events lasting 90+ minutes. Not an excuse to overeat — the goal is shifting macronutrient ratios, not total calories.
- Cardiac Drift
- The gradual increase in heart rate during a steady-effort run, even when pace stays the same. Caused by dehydration, rising core temperature, and redistribution of blood flow. Normal and expected, especially in heat.
- Chip Time
- Your actual race time measured from when you cross the start line to when you cross the finish. More accurate than gun time for large races where it may take minutes to reach the start after the gun fires.
- Cooldown
- Easy running or walking done after a hard workout or race to gradually lower heart rate and begin the recovery process. Typically 5-15 minutes. Helps clear metabolic byproducts from working muscles.
- Corral
- A designated starting area in a race, usually assigned by predicted finish time. Faster runners start in earlier corrals to reduce congestion. Your corral assignment often appears on your bib.
- Cross-Training
- Non-running exercise that supports your running — cycling, swimming, strength work, yoga. Maintains cardiovascular fitness while reducing impact stress. Useful during injury recovery or as a complement to running.
D
- Deload Week
- A planned reduction in training volume (typically 20-40% less mileage) to allow recovery and adaptation. Usually scheduled every 3-4 weeks during a training cycle. Also called a recovery week or cutback week.
- Dew Point
- A measure of humidity that tells you how much moisture is in the air. More useful than relative humidity for runners. Above 60°F, running performance measurably degrades. Above 70°F, conditions are genuinely difficult.
- DNF
- Did Not Finish — a race result meaning the runner started but didn't complete the course. Can be voluntary (illness, injury) or involuntary (course cutoff). Also not a failure.
- DNS
- Did Not Start — a race result meaning the runner registered but didn't begin the race. Not a failure. Sometimes the smart call.
- DOMS
- Delayed Onset Muscle Soreness — the stiffness and tenderness that peaks 24-72 hours after hard or unfamiliar exercise. Caused by microscopic muscle damage during eccentric contractions. Normal and temporary.
- Double
- Running twice in one day — typically a main workout and a shorter easy run. Common in high-mileage training plans (50+ miles/week) to accumulate volume without individual runs being too long.
- Drop
- The difference in height between the heel and forefoot of a running shoe, measured in millimeters. Traditional shoes are 10-12mm. Minimalist shoes are 0-4mm. Most runners do fine with whatever they're accustomed to.
- Dynamic Stretching
- Active movements that take joints through their full range of motion — leg swings, high knees, butt kicks. Better as a warm-up than static stretching, which is more appropriate for cooldowns.
E
- Easy Pace
- A conversational effort — you should be able to speak in full sentences. For most runners this feels surprisingly slow. Typically 60-75% of maximum heart rate or RPE 3-4 out of 10.
- Electrolytes
- Minerals (sodium, potassium, magnesium, calcium) lost through sweat that are essential for muscle function and hydration. Most runners don't need supplemental electrolytes for runs under 60-90 minutes if they eat a normal diet.
- Even Split
- Running both halves of a race or workout at approximately the same pace. A solid, conservative strategy. Slightly less optimal than a negative split but far better than a positive split.
F
- Fartlek
- Swedish for "speed play." An unstructured workout where you alternate between faster and slower running based on feel — sprint to that tree, jog to the next corner. Good for beginners learning to incorporate speed work without the pressure of specific splits.
- Foam Rolling
- Self-massage using a cylindrical foam roller to release muscle tension and improve mobility. Evidence for injury prevention is mixed, but many runners find it helps with recovery and reducing soreness. Not a substitute for stretching.
- Foot Strike
- How your foot contacts the ground — forefoot, midfoot, or heel. There's no universally "correct" foot strike despite what you may have heard. Most recreational runners heel strike and do fine. Forced changes cause more injuries than they prevent.
G
- GAP
- Grade Adjusted Pace — an estimate of what your pace would have been on flat ground, accounting for hills. A 9:00/mile pace on a steep uphill might equal a 7:30 GAP, meaning your effort was equivalent to running 7:30s on flat terrain.
- Glycogen
- Stored carbohydrate in your muscles and liver — your body's primary fuel source during moderate-to-hard running. You can store roughly 90-120 minutes worth. When it runs out, you bonk.
- Gray Zone
- The moderate-intensity range that's too hard to count as easy running but not hard enough to produce the stimulus of a quality workout. Running too much in this zone is the most common mistake recreational runners make.
- Ground Contact Time
- How long each foot stays on the ground per stride, measured in milliseconds. Faster runners spend less time on the ground (180-220ms) than slower runners (250-300ms). Improves naturally with fitness — not something to consciously manipulate.
- Gun Time
- Your race time measured from when the starting gun fires, regardless of when you personally cross the start line. In large races, your chip time will be more accurate.
H
- Half Marathon
- 13.1 miles (21.1 km). The most popular race distance in the United States. Long enough to require real training but short enough to recover from relatively quickly.
- Heart Rate Zones
- Ranges of heart rate intensity used to guide training. Typically divided into 5 zones from easy (Zone 1) to maximum effort (Zone 5). Useful when calibrated to your actual max heart rate, but the common "220 minus age" formula is unreliable.
- Hill Repeats
- A workout where you run hard up a hill, then jog or walk back down, and repeat. Builds leg strength, improves running economy, and provides speed work with lower injury risk than flat intervals because the incline limits your pace.
- Hitting the Wall
- See Bonk. The sudden, severe fatigue that occurs when glycogen stores are depleted, most commonly around miles 18-22 of a marathon.
I
- Interval Training
- Structured speed work alternating between hard efforts and recovery periods. Common formats: 400m repeats, 800m repeats, mile repeats. Improves VO2max, running economy, and speed. Should make up a small portion (10-20%) of total training.
- IT Band Syndrome
- Pain on the outside of the knee caused by the iliotibial band — a thick strip of tissue running from hip to shin — rubbing against the knee joint. One of the most common running injuries. Often caused by training load spikes rather than biomechanical issues.
J
- Junk Miles
- A term (often misused) for running that supposedly serves no training purpose. In reality, almost all easy running has value — it builds aerobic capacity and strengthens connective tissue. The real "junk" is gray zone running that's neither easy enough to recover from nor hard enough to improve.
K
- Kick
- A surge of speed in the final portion of a race. Requires both physical fitness and strategic pacing — you can't kick if you've been running too hard for the first 90% of the race.
L
- Lactate Threshold
- The exercise intensity at which lactate accumulates in the blood faster than your body can clear it. Training at or near this threshold (tempo runs, threshold intervals) improves your ability to sustain harder efforts for longer.
- Long Run
- The longest run of the week, typically done at easy effort. Builds endurance, teaches your body to burn fat as fuel, develops mental toughness, and strengthens connective tissue. Generally 25-30% of your total weekly mileage.
- LSD
- Long Slow Distance — an older term for what we now call the long run. The key insight: it should genuinely be slow. If your long run leaves you wrecked for two days, you ran it too fast.
M
- Marathon
- 26.2 miles (42.2 km). Named after the Greek city of Marathon, though the historical story about Pheidippides is mostly legend. The distance was standardized at the 1908 London Olympics.
- Max Heart Rate
- The highest heart rate your body can achieve during all-out exertion. Genetically determined and not meaningfully changed by training. The "220 minus age" formula is a rough average with a standard deviation of ±10-12 beats — meaning it's wrong for most people.
N
- Negative Split
- Running the second half of a race or workout faster than the first half. Generally the optimal pacing strategy for distance events — requires restraint early and rewards patience.
O
- Out-and-Back
- A route or race course where you run to a turnaround point and return the same way. Useful for time-based workouts and for knowing exactly where you are relative to the finish.
- Overpronation
- Excessive inward rolling of the foot after landing. Historically blamed for many running injuries, but current research suggests it's less of a problem than the shoe industry claimed. Most runners don't need "motion control" shoes.
- Overreaching
- A short-term state of accumulated fatigue from intentionally hard training. Unlike overtraining, overreaching is temporary and resolves with a few days of rest. Some planned overreaching followed by recovery leads to supercompensation.
- Overtraining
- A chronic state of fatigue and declining performance caused by training more than your body can recover from over weeks or months. Symptoms: persistent tiredness, elevated resting heart rate, irritability, frequent illness, lost motivation. Recovery can take weeks to months.
P
- Pace
- How fast you're running, expressed as minutes per mile or minutes per kilometer. A 9:00/mile pace means it takes 9 minutes to cover one mile. Not the same as effort — the same pace feels very different in heat, on hills, or when fatigued.
- Pacer
- A runner in a race (often a volunteer) who maintains a specific target pace to help other runners hit their goals. Usually carries a sign or flag showing their target finish time.
- Periodization
- Organizing training into distinct phases — base, build, peak, taper — with different focuses in each. Prevents stagnation, manages fatigue accumulation, and peaks fitness for goal races.
- Plantar Fasciitis
- Inflammation of the thick band of tissue connecting the heel to the toes, causing heel pain that's typically worst in the morning. One of the most common running injuries. Often caused by too-rapid increases in training volume.
- Positive Split
- Running the second half of a race or workout slower than the first half. Usually means you went out too fast. It happens to everyone at least once.
- PR / PB
- Personal Record / Personal Best — your fastest time for a given distance. Some runners distinguish between PR (best ever in a race) and PB (best ever including training runs), but most use them interchangeably.
- Progression Run
- A run that starts easy and gradually gets faster, finishing at a moderate or hard effort. Teaches pacing discipline and builds the ability to run fast on tired legs. A controlled version of the negative split.
- Progressive Overload
- Gradually increasing training stress over time to stimulate continued adaptation. In running, this means slowly adding mileage, intensity, or both — not all at once, and not every week. The only way your body gets stronger.
R
- Race Pace
- The pace you intend to maintain during a goal race. Different from training paces — most of your training should be slower than race pace. Practicing race pace in workouts helps your body learn what it feels like.
- Recovery Run
- A very short, very easy run done the day after a hard workout. Promotes blood flow to aid recovery without adding significant training stress. Should feel effortless — if you have to think about slowing down, you're going too fast.
- Repeats
- Multiple efforts at the same distance and intensity with recovery between them. "6 x 800m" means six 800-meter intervals. The rest between repeats matters as much as the effort during them.
- RPE
- Rate of Perceived Exertion — a subjective 1-10 scale for how hard a workout feels. Accounts for factors heart rate and pace miss: sleep quality, stress, heat, accumulated fatigue. RPE 3-4 is easy, 5-6 is moderate, 7-8 is hard, 9-10 is all-out.
- Runner's Knee
- Pain around or behind the kneecap (patellofemoral pain syndrome). One of the most common running injuries. Despite the name, it's usually a training load issue rather than a structural knee problem.
- Running Economy
- How efficiently you use oxygen at a given pace — the running equivalent of fuel economy. Better economy means you use less energy to run the same speed. Improves with consistent training, strength work, and proper form.
S
- Shin Splints
- Pain along the front or inner edge of the shinbone (medial tibial stress syndrome). Almost always a load management problem — too much volume or intensity too fast. The fix is reducing load, not pushing through it.
- Specificity
- The principle that training adaptations are specific to the type of training you do. Running makes you better at running. Speed work makes you faster. Long runs build endurance. Your training should match your goal race demands.
- Speed Work
- Any running done at a pace significantly faster than your easy pace — intervals, tempo runs, fartlek, strides, hill repeats. Should make up about 20% of your total training volume. The other 80% should be easy.
- Splits
- Your time for each segment of a run or race — per mile, per kilometer, or per lap. "Mile splits" tells you how fast you ran each mile. Watching your splits helps identify pacing patterns.
- Stack Height
- The amount of cushioning material between your foot and the ground in a running shoe, measured in millimeters. Higher stack = more cushioning. Modern "super shoes" can have 35-40mm of stack.
- Steady State Run
- A run at a consistent, moderate effort — harder than easy but softer than tempo. Roughly marathon effort for experienced runners. Builds aerobic capacity and teaches sustained pacing.
- Stress Fracture
- A small crack in a bone caused by repetitive impact. Requires significant time off (typically 6-8 weeks minimum). Almost always caused by training load errors — increasing volume or intensity too fast without adequate recovery.
- Strides
- Short accelerations (typically 80-100 meters) at near-sprint effort with full recovery between. Done 4-6 times after easy runs to maintain turnover speed and running form without adding significant fatigue to the day.
- Supercompensation
- The brief window after recovery from a hard training stimulus where your fitness is slightly higher than before. This is the mechanism behind progressive overload — stress, recover, come back slightly stronger.
T
- Taper
- A planned reduction in training volume in the 1-3 weeks before a goal race. Allows your body to fully recover while maintaining fitness. Volume drops 40-60% but some intensity stays. Feeling sluggish and restless during taper is completely normal.
- Tempo Run
- A sustained effort at or near lactate threshold pace — "comfortably hard." You can speak in short phrases but can't hold a conversation. Typically 20-40 minutes. One of the most effective workouts for improving race performance.
- Training Block
- A structured period of training (typically 3-4 weeks) with a specific focus — building base, developing speed, sharpening for a race. Usually ends with a deload week before the next block.
- Training Load
- A measure of how much stress a workout places on your body. In Pacewright, calculated as duration (minutes) multiplied by RPE (1-10). Used to track fitness, manage fatigue, and calculate ACWR.
- Training Plan
- A structured schedule of workouts designed to prepare you for a specific goal — a race distance, a time target, or general fitness. Good plans include easy days, hard days, long runs, rest days, and built-in flexibility.
U
- Ultra
- Any race longer than a marathon (26.2 miles). Common distances: 50K, 50 miles, 100K, 100 miles. A completely different sport from road running in terms of training, nutrition, and pacing.
V
- VO2max
- The maximum amount of oxygen your body can use during exercise, measured in mL/kg/min. A key indicator of aerobic fitness that improves with consistent training, especially interval work. Not the only factor in race performance — running economy and threshold matter too.
- Volume
- Total weekly running mileage or time. One of the three primary training variables alongside intensity and frequency. Increasing volume too quickly is the single most common cause of running injuries.
W
- Walk Break
- Planned walking intervals during a run, used as a strategy in training and racing. Not a sign of weakness — the run/walk method (popularized by Jeff Galloway) helps many runners finish longer distances while reducing injury risk.
- Warm-Up
- Easy running and dynamic movements done before a hard workout or race to increase blood flow, raise body temperature, and prepare muscles for effort. Typically 10-15 minutes of easy jogging plus dynamic stretches.
Y
- Yasso 800s
- A marathon fitness test created by Bart Yasso. Run 10 x 800m intervals; if you can average them in 3 minutes 30 seconds, you're roughly fit for a 3:30 marathon. A useful rough estimate, not a precise prediction.
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