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Everything you need to know to get better at road and trail running.

📖 Running glossary

All the technical terms you’ll come across in your training plans, on your watch or when talking with other runners.

A
Aerobic threshold
The intensity at which lactate starts to rise slightly. It matches the top of Z2.
Aid station
A food and drink stop during a race. Well stocked on the road; on trails you’re often more self-sufficient.
ATL
Acute Training Load. A weighted average over 7 days that reflects recent fatigue.
B
BPM
Beats per minute, the unit used to measure heart rate.
C
Cadence
The number of steps per minute. An efficient cadence usually sits around 170-185 steps per minute, depending on speed.
Cardiac drift
The gradual rise in heart rate at a steady pace, caused by dehydration and fatigue. Normal up to 5-7%.
Cramp
An involuntary, painful muscle contraction, often linked to fatigue, dehydration or an electrolyte imbalance.
CTL
Chronic Training Load. A weighted average of your load over 42 days that reflects your underlying fitness.
D
Drop
The height difference in mm between the heel and the forefoot of a shoe. It ranges from 0 mm (minimalist) to 12 mm.
E
Easy pace
A slow, comfortable aerobic pace that lets you hold a conversation. Most of your running should happen here.
Effort-km
Distance in km + elevation gain in meters ÷ 100. Measures the real difficulty of a trail course.
Elevation gain / loss
The total climbing (gain) and descending (loss) on a course, in feet or meters.
F
Fartlek
Swedish for “speed play.” A session of free-form surges with no rigid structure.
G
Glycogen
Carbohydrate stored in your muscles and liver: the main fuel when you run.
I
Intervals
Training that alternates fast efforts with slower recovery periods.
ITRA
International Trail Running Association. The body that rates trail races and trail runners.
L
Lactate
A by-product of anaerobic metabolism. When it builds up, you feel the “burn” in your muscles.
Lactate threshold
The intensity above which lactate builds up faster than it’s cleared. Sustainable for 45-60 minutes at most.
Long run
The longest run of the week, the key to marathon training. Done at an easy pace.
LSD
Long Slow Distance. A long run at an easy pace to build aerobic endurance.
M
MAS
Maximal aerobic speed (or vVO₂max): the speed at which your oxygen uptake peaks.
Max HR
Maximum heart rate: the highest number of beats per minute your heart can reach.
Mesocycle
A 3- to 6-week training block with a specific goal (base, build, taper…).
N
Negative split
A race strategy where you run the second half faster than the first.
P
Pace
Running speed expressed in minutes per mile (min/mi) or per kilometer. E.g. 8:00/mi = 7.5 mph.
Periodization
Organizing training into progressive phases toward a goal (base, build, taper).
PR / PB
Personal record / personal best: your fastest time over a given distance.
Pronation
The natural inward roll of the foot on landing. It can be neutral, overpronation or supination.
R
Resting HR
Your heart rate at rest, measured on waking. A good indicator of fitness.
RPE
Rate of Perceived Exertion. A 1-10 scale to rate how hard an effort feels.
T
Taper
The pre-race sharpening phase: volume cut by 30-50% while intensity is maintained.
Tempo
A “comfortably hard” pace, between the aerobic and lactate thresholds. Roughly half marathon pace.
The wall
The sudden exhaustion of your glycogen stores, typically around mile 20 of a marathon. Avoided with good pacing and fueling.
TRIMP
Training Impulse. A measure of training load that combines duration and intensity.
TSB
Training Stress Balance = fitness (CTL) - fatigue (ATL). An indicator of how fresh you are on the day.
V
VDOT
A fitness index created by Jack Daniels. It’s used to estimate your training paces and race times.
VO₂max
The maximum volume of oxygen your body can use per minute. A key marker of aerobic performance.
Z
Z1 to Z7
Intensity zones from Z1 (recovery) to Z7 (sprint). Each zone targets a different energy system.

💓 Understanding intensity zones

Training zones define how hard your sessions are. They’re based on your maximum heart rate (max HR) or your maximal aerobic speed (MAS).

The 5 heart-rate zones

Z1
Recovery
50-60% of max HR

Very easy jogging, active recovery between hard sessions.

Z2
Easy aerobic
60-70% of max HR

The most important zone. About 80% of your training should happen here.

Z3
Tempo
70-80% of max HR

A “comfortably hard” effort, typical of marathon or half marathon pace.

Z4
Threshold
80-90% of max HR

A sustained effort you can hold for 30-60 minutes. Breathing is hard, short sentences only.

Z5
VO₂max
90-100% of max HR

A maximal effort you can hold for 3-8 minutes. Completely out of breath.

💡 Tip

The talk test is the simplest check: if you can talk normally, you’re in Z1-Z2. If you can only get a few words out, you’re in Z4-Z5.

The 80/20 rule

Elite athletes spend about 80% of their time in zones 1-2 and only 20% in zones 4-5. Zone 3 (the “gray zone”) is best avoided: too hard to recover from, not hard enough to drive progress.

How do you find your max HR?

  • Theoretical formula: 220 - age (not very accurate, ±10 bpm).
  • Field test: 3 × 3 min all-out uphill with 1 min of recovery. The peak heart rate on the last one is your max HR.
  • RunMorph: the real max HR recorded across 12 months of imported runs. The most reliable option.

🍽️ Nutrition and hydration

Nutrition is the fourth pillar of performance.

Before you run

  • 2-3 h before: complex carbs, low in fiber and fat.
  • 30 min before: a banana or a bar if you need it.
  • Hydration: 14-20 oz (400-600 ml) of water.

During your run

  • Under 1 h: water is enough.
  • 1-2 h: 5-7 oz every 15 min, plus a sports drink.
  • Over 2 h: 60-90 g of carbs per hour. Start from the 30-minute mark.

After your run

  • First 30 min: the recovery window. Carbs + protein, in a 3:1 ratio.
  • Meal: a full meal within 2 hours.
  • Rehydration: about 24 oz for every pound you lost.

Before a race

  • 3 days to 1 day out: 65-70% carbohydrates.
  • The night before: a familiar, low-fiber meal.
  • Race morning: breakfast 3 hours before. Nothing new.
⚠️ Golden rule

NEVER try new fueling on race day. Everything should be tested in training.

😴 Managing fatigue and recovery

You get fitter while you recover, not while you train.

Sleep

  • 7-9 hours a night: the number one recovery factor.
  • A cool (around 65°F), dark bedroom, and no screens for an hour before bed.
  • A 20-30 minute nap if you need it.

Signs of overtraining

  • Resting heart rate 5+ bpm higher in the morning
  • Persistent fatigue, falling performance
  • Irritability, trouble sleeping, loss of appetite
  • Recurring injuries, frequent infections
⚠️ What to do?

Three or more signs? Cut your volume by 50% for 1-2 weeks. See a doctor if it persists.

Active recovery

20-30 minutes of very easy jogging the day after a hard session boosts blood flow.

Put it into practice

Work out your paces, zones and race times with our free running calculators.

Open the running tools

🩹 Injury prevention

Up to 80% of runners get injured each year. Most of those injuries can be avoided.

The most common injuries

  • IT band syndrome: pain on the outside of the knee. Mileage increased too fast.
  • Shin splints: pain along the shin. Common in beginners.
  • Plantar fasciitis: pain under the heel when you wake up. Overload.
  • Achilles tendinopathy: a sudden change in intensity.
  • Stress fracture: a tiny crack in the bone caused by overload.

How to avoid them

  • The 10% rule: never increase your weekly volume by more than 10%.
  • Strength work: 2-3 sessions of 20 minutes a week = 50% less risk.
  • Warm-up: 10-15 minutes before every hard session.
  • Shoes: replace them every 400-500 miles.
💡 Strength work is non-negotiable

15 minutes of core work and squats 3 times a week protects your joints.

🏁 Race strategy

On race day, how you manage your effort makes all the difference.

5K

Start at goal pace after a 15-20 minute warm-up. Speed up over the last half mile.

10K

Start 10-15 s/mi slower over the first mile. Keep something in reserve.

Half

Start 15-25 s/mi slower for the first 3 miles. Goal pace from mile 3 to mile 10. Pick it up over the last 3 miles if you can.

Marathon

Miles 1-6: EASY. Miles 6-18: steady. Miles 18-22: the wall. Miles 22-26.2: break it into one-mile chunks.

💡 Marathon fueling

1 gel every 30-40 minutes (4-5 gels). 5-7 oz of water at every aid station. Start around mile 3.

Choosing your gear?

In-depth reviews of running shoes, watches and gear: lab data, field tests and a clear verdict.

Read our gear reviews

📋 Training principles

The science-based fundamentals of an effective training plan.

Periodization

Phase 1Base4-6 wks

Gradually more volume at an easy aerobic effort.

Phase 2Build4-6 wks

Quality sessions (threshold, VO₂max).

Phase 3Specific3-4 wks

Race-pace sessions, goal-pace blocks.

Phase 4Taper2-3 wks

Volume down 30-50%, intensity maintained.

Types of sessions

Easy aerobic run
60-75% max HR45 min - 1:30
The foundation
Long run
60-70% max HR1:30 - 3:00+
Endurance base
Short intervals (VO₂max)
95-100%30/30s, 200s, 400s
VO₂max
Long intervals (threshold)
80-90%3 × 8 min, 2 × 15 min
Lactate threshold
Tempo
75-85%20-40 min
Running economy
Hills
Max effort6-12 × 30-90 s
Strength and power

Progression (ACWR)

Your acute-to-chronic workload ratio should stay between 0.8 and 1.3. In practice: +10% a week at most, and a recovery week every 4 weeks.

⛰️ Trail running essentials

Trail running comes with its own demands: climbing, technical terrain, self-sufficiency.

Climbing

  • Beyond a 15-20% grade, power-hiking is more economical.
  • Pace yourself on your breathing (80-85% of max HR).
  • 1,000-2,300 ft of climbing per hour, depending on your level.

Descending

  • Short, quick steps, knees bent.
  • Eyes 10-13 ft ahead, weight slightly forward.

Self-sufficiency

  • A 5-12 L vest, 17 oz (500 ml) of water and 60-90 g of carbs per hour.
  • Poles pay off beyond about 5,000 ft of climbing.

Effort-km

Effort-km = distance (km) + gain (m) ÷ 100

E.g. 25 mi (40 km) with 6,560 ft (2,000 m) of climbing = 60 effort-km

👟 Gear

The wrong gear can get you hurt. The right gear helps you improve.

Shoes

  • Drop: 8-12 mm (beginners) / 4-8 mm (experienced runners).
  • Lifespan: 400-500 miles on the road, 250-375 miles on trails.
  • Rotation: 2-3 pairs = 40% less injury risk.

Clothing

  • Breathable technical fabrics (no cotton).
  • Seamless running socks.
  • In cold weather: dress as if it were 20°F warmer.

🧠 Mental preparation

When your legs get tired, your mind makes the call.

During the race

  • Chunking: never think about the full distance. One segment at a time.
  • Mantras: “Strong and steady,” “One step at a time.”
  • Breathing: a 3:2 rhythm (breathe in for 3 steps, out for 2).

Handling the wall

  • Accept it. It’s normal, not a failure.
  • Shorten your stride. Focus on your form.
  • Remember the hard sessions you’ve already gotten through.

Visualization

The night before, picture every phase of the race. Visualization fires up the same circuits as the real thing.

💡 Train your mind too

Every tough session builds your confidence for race day.

Ready to transform your stride?

Personalized RunMorph training plans are coming soon in English.

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