Home Help center

Help center

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.

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 of your training load over about 7 days. It reflects your recent fatigue.

BPM

Beats per minute, the unit used to measure heart rate.

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%.

Climbing rate

The elevation gained per hour on the climbs of a run (m/h), on sections of at least a 5% grade. Often between 600 and 1,200 m/h (2,000-3,900 ft/h) in trail running, depending on level and gradient.

Cramp

An involuntary, painful muscle contraction, often linked to fatigue, dehydration or an electrolyte imbalance.

CTL

Chronic Training Load: a weighted average of your training load over about 42 days. It reflects your underlying fitness.

Drop

The height difference in mm between the heel and the forefoot of a shoe. It ranges from 0 mm (minimalist) to 12 mm.

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, the ITRA convention. It measures the real difficulty of a trail course. Descent is not counted: the variant that adds elevation loss ÷ 400 is not ITRA’s.

Elevation gain / loss

The total climbing (gain) and descending (loss) on a course, in meters (or feet).

Fartlek

Swedish for “speed play.” A session of free-form surges with no rigid structure.

Form (TSB)

Training Stress Balance: your chronic load (CTL) minus your acute load (ATL) as of the day before. Negative after a big block, it rises again with rest; a form of +5 to +25% of your CTL is a good time for a race.

Glycogen

Carbohydrate stored in your muscles and liver: the main fuel when you run.

Grade-adjusted pace

The flat-ground equivalent pace of a hilly run (GAP): climbs count as more distance, gentle descents as a little less, steep descents as more again. RunMorph calculates it with a table calibrated on heart rate, close to Strava’s GAP.

Heart-rate reserve

The gap between your max HR and your resting HR. The Karvonen method uses it for heart-rate zones: target HR = resting HR + % × heart-rate reserve. Example: max HR 190, resting 55, heart-rate zone Z2 (60-70%) runs from 136 to 150 bpm.

Heart-rate zone

A heart-rate range, from Z1 to Z5, as a percentage of your heart-rate reserve: Z1 50-60%, Z2 60-70%, Z3 70-80%, Z4 80-90%, Z5 90-100%. Not to be confused with a pace zone (Z1 to Z7, as a % of MAS), even though their numbers match up to Z5.

Hourly elevation gain

Total elevation gain divided by the moving time of the whole run (m/h). Lower than the climbing rate, since it also counts flat sections and descents. Handy for setting an elevation target on a long run.

Intervals

Training that alternates fast efforts with slower recovery periods.

ITRA

International Trail Running Association. The body that rates trail races and trail runners.

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 about an hour in a race. It’s pace zone Z4 (84-92% of MAS; one-hour pace is about 86% of MAS) and heart-rate zone Z4.

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.

MAS

Maximal aerobic speed (or vVO₂max). RunMorph uses the field MAS: the speed you can hold for about 6 minutes all-out, the one measured by the half-Cooper and VAMEVAL tests. All your pace zones follow from it. The rule of thumb “VO₂max ≈ 3.5 × MAS” only gives a ballpark figure.

Max HR

Maximum heart rate: the highest number of beats per minute your heart can reach. RunMorph uses your measured value, otherwise the highest reliable value recorded over 12 months of runs, otherwise the Tanaka formula (208 - 0.7 × age).

Mesocycle

A 3- to 6-week training block with a specific goal (base, build, taper…).

Negative split

A race strategy where you run the second half faster than the first.

Pace

Running speed expressed in minutes per kilometer (min/km), or per mile (min/mi). E.g. 5:00/km = 12 km/h (8:03/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.

Resting HR

Your heart rate at rest, measured on waking, lying down. A good indicator of fitness, and the starting point of your heart-rate reserve. Without a value, RunMorph estimates it from your data, otherwise uses 55 bpm.

RPE

Rate of Perceived Exertion. A 1-10 scale to rate how hard an effort feels.

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: marathon pace, pace zone Z3 (76-83% of MAS).

The wall

The sudden exhaustion of your glycogen stores, typically around km 30 of a marathon (mile 18-20). Avoided with good pacing and fueling.

Training load

The effort of a session on a single scale, where 100 equals 1 hour at threshold: calculated from your heart rate when you have it, otherwise from your grade-adjusted pace. Light runs score under 50, high-load sessions 150 and more.

TRIMP

Training Impulse (Banister): a load measure that combines duration and heart-rate intensity. RunMorph uses it for its training load, scaled so that 100 equals 1 hour at threshold.

VDOT

A performance index created by Jack Daniels, calculated from your race times: it includes your running economy and how well you sustain the effort. It is not your VO₂max, which is usually higher. RunMorph uses it to link your MAS, your training paces and your race predictions.

VO₂max

The maximum volume of oxygen your body can use per minute (ml/kg/min), a key marker of aerobic performance. RunMorph estimates it from your heart rate and pace over your last 10 runs, within about ±10%, and compares it with the general population (FRIEND registry) when your age and sex are filled in. Not to be confused with VDOT, which sets your paces and race predictions.

Z1 to Z7

Intensity zones. Pace zones run from Z1 (recovery, 55-65% of MAS) to Z7 (sprint, over 110%); heart-rate zones run from Z1 to Z5, as a percentage of heart-rate reserve. Pace zone Z2 matches heart-rate zone Z2, and so on up to Z5.

💓 Understanding intensity zones

Training zones define how hard your sessions are. RunMorph uses two families: 7 pace zones, as a percentage of your field maximal aerobic speed (MAS, the speed you can hold for about 6 minutes all-out), and 5 heart-rate zones, as a percentage of your heart-rate reserve (Karvonen method). Pace zone Z2 matches heart-rate zone Z2, and so on up to Z5.

The 5 heart-rate zones

Recovery

50-60% of HR reserve

Very easy jogging, active recovery between hard sessions.

Easy endurance

60-70% of HR reserve

The most important zone: most of your volume happens here.

Tempo

70-80% of HR reserve

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

Threshold

80-90% of HR reserve

A sustained effort you can hold for 30-60 minutes. Breathing is hard, a few words only.

MAS / VO₂max

90-100% of HR reserve

A very hard effort you can hold for 3-6 minutes. Talking is impossible.

Target HR = resting HR + % × (max HR - resting HR). With a max HR of 190 bpm and a resting HR of 55 bpm, heart-rate zone Z2 runs from 136 to 150 bpm. As a percentage of max HR, the 60, 70, 80 and 90% reserve thresholds land around 72, 79, 86 and 93%.

The 7 pace zones

Recovery

55-65% of MAS

Very easy jogging, warm-ups. Heart-rate zone Z1.

Easy endurance

65-75% of MAS

Easy runs, long runs. Heart-rate zone Z2.

Tempo / marathon pace

76-83% of MAS

Marathon pace, steady aerobic running. Heart-rate zone Z3.

Threshold

84-92% of MAS

Half marathon to 10K pace; the pace you hold for 1 hour is about 86% of MAS. Heart-rate zone Z4.

MAS

95-100% of MAS

Repeats of 3 to 6 minutes. Heart-rate zone Z5.

Anaerobic capacity

102-110% of MAS

Repeats of 30 seconds to 2 minutes. HR not relevant: go by pace.

Speed / sprint

over 110% of MAS

Sprints under 30 seconds. HR not relevant.

💡 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 or above.

The 80/20 rule

Endurance runners spend about 80% of their time in zones 1-2 and 20% above. Zone 3 (tempo, marathon pace) has its place, especially when training for a marathon: dose it in planned sessions rather than letting it become the pace of every easy run.

How do you find your max HR?

Formula: Tanaka, 208 - 0.7 × age (within about ±10 bpm; 220 - age is less accurate).
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: your measured max HR if you enter it in “My reference values”; otherwise the max HR recorded across 12 months of runs (one of the highest, not an isolated spike; walks and hikes don’t count), never below Tanaka while you have few runs with heart rate; otherwise Tanaka.

Measure your resting heart rate on waking, lying down. Without a value, RunMorph estimates it from your data, otherwise uses 55 bpm. Your MAS comes from your measurement in “My reference values” (less than 12 months old), otherwise from a race or all-out effort in the last 6 months, otherwise from an estimate based on your runs: the source is always shown.

Calculate my MAS with the RunMorph tool Estimate my max HR Calculate my training zones

🍽️ 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: 400-600 ml (14-20 oz) of water.

During your run

Under 1 h: water is enough.
1-2 h: 150-200 ml (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: 1.5 times the weight you lost (about 1.5 L per kg, 24 oz per pound).

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.

Calculate the calories I burn per run

😴 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 18°C / 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 600-800 km (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.

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

10K

Start 5-10 s/km slower over the first 2 km. Keep something in reserve.

Half

Start 10-15 s/km slower for the first 5 km. Goal pace from km 6 to km 16. Pick it up over the last 5 km if you can.

Marathon

Km 1-10: EASY. Km 10-30: steady. Km 30-35: the wall. Km 35-42: break it into 1 km chunks.

💡 Marathon fueling

1 gel every 30-40 minutes (4-5 gels). 150-200 ml (5-7 oz) of water at every aid station. Start around km 5.

Calculate my race pace Predict my finish time Calculate my race splits

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

Z2 · 65-75% MAS45 min - 1 h 30

The foundation

Long run

Z2 · 65-75% MAS1 h 30 - 3 h and more

Endurance base

Short intervals (VO₂max)

Z5 · 95-100% MAS30/30s, 200s, 400s

VO₂max

Long intervals (threshold)

Z4 · 84-92% MAS3 × 8 min, 2 × 15 min

Threshold

Tempo

Z3 · 76-83% MAS20-40 min

Marathon pace

Hills

Max effort6-12 × 30-90 s

Strength and power

Progression: training load and form

RunMorph measures the load of each run on a single scale, where 100 equals 1 hour at threshold: with your heart rate when you have it, otherwise with your grade-adjusted pace. Your chronic load (about 6 weeks) reflects your fitness, your acute load (about 1 week) your recent fatigue. Your form is the gap between the two: negative after a big block, it rises again with a few lighter days, and a “fresh” form (+5 to +25% of your chronic load) is a good time for a race. To progress, raise your weekly load gradually (the usual guideline is about +10% a week) and plan a lighter week every 3 to 4 weeks; once you have 5 weeks of history, RunMorph shows how your load compares with the average of your previous 4 weeks.

See a sample marathon plan See a sample trail plan

⛰️ 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, around heart-rate zone Z3 (70-80% of HR reserve).
300-700 m (1,000-2,300 ft) of climbing per hour, depending on your level.

Descending

Short, quick steps, knees bent.
Eyes 3-4 m (10-13 ft) ahead, weight slightly forward.

Self-sufficiency

A 5-12 L vest, 500 ml (17 oz) of water and 60-90 g of carbs per hour.
Poles pay off beyond about 1,500 m (5,000 ft) of climbing.

Effort-km

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

E.g. 40 km (25 mi) with 2,000 m (6,560 ft) of climbing = 60 effort-km. Descent is not counted.

RunMorph trail plan Calculate my 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: 600-800 km on the road (400-500 miles), 400-600 km on trails (250-375 miles).
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 10°C (20°F) warmer.

Read our gear reviews

🧠 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?

Create your free account and get your personalized training plan in a few minutes.

Create my free plan

Free to start · No credit card · Cancel in 1 click