Before you start
5 things to know
- No books, no TV. Points at creation are the only shortcut. Chapter 2
- Stay at 75 to 85 kg. That removes the weight penalties. Chapter 5
- Never train exhausted, hurt or on the morning of a raid. Chapter 7
- Rotate body parts. Squats one day, push-ups the next. Chapter 8
- Train Very Tired and exercise stiffness doubles. Sleep first. Chapter 9
Chapter 1
Fitness and Strength in Build 42
Every other skill is about a task. These 2 are about your body, and your body is in every task.
Fitness and Strength start at level 5, not 0. They need far more XP per level than other skills. They get no boost from starting points. And they can slowly go down if you stop training for weeks. In Build 42 they are a real training system with an Exercise menu, regularity, stiffness and muscle strain.
Fitness
Stamina, attack speed, climbing. The fight-and-flight stat.
Strength
Damage, shove, carry weight, less muscle strain. The haul-and-hit stat.
The body loop
- EatEnough calories, with protein.
- Train10 to 20 minutes, 1 or 2 moves.
- RestStiffness fades overnight.
- LiveFight, haul, run. Passive XP.
- Weigh inStay in the healthy band.
Why it matters
An exhausted survivor misses swings. A weak one cannot carry the loot home. Every guide in this series assumes a body that works.
Chapter 2
Build your body
These skills are so slow that buying levels at creation is the single best use of points in the game.
Athletic (trait, 10 points)
+4 Fitness. Expensive. Worth it. Most veterans call this the best trait in the game.
Fit (trait, 6 points)
+2 Fitness. The budget version.
Strong (trait)
+4 Strength. Stout is +2.
Fitness Instructor (job)
+3 Fitness, +2 Running, +1 Strength, and 40 to 60% starting regularity on every exercise. It costs 6 points.
Firefighter, Lumberjack, Farmer (jobs)
Each starts with Strength or Fitness above 5.
Puny, Weak, Unfit, Out of Shape
Negative traits that lower these. They can be trained away.
Watch out: point costs change
The game makers still tune traits and jobs. Always read the numbers on your own character screen.
Secret: no books, no TV, no boost
Fitness and Strength ignore the starting-point XP boost and have no skill books. What you buy at creation is the only shortcut.
Chapter 3
What Fitness does
- Endurance. Higher Fitness means slower exhaustion. Exhausted swings miss and do less damage.
- Attack speed. Faster melee swings.
- Climbing. Faster and more reliable over fences and through windows.
- Sprinting. Longer before your lungs give out.
Secret: Fitness beats Strength long-term
Player consensus: Strength has efficient training methods, Fitness does not. If you buy one at creation, buy Fitness.
Chapter 4
What Strength does
- Carry weight. Roughly 8 times a strength multiplier, minus penalties for hunger, thirst, sickness, bleeding and injury. Level 5 is the baseline. Level 10 carries a lot more.
- Melee damage and knockback. Less than weapon skill, but it stacks.
- Shove and knockdown. Better pushes.
- Windows and fences. Easier to open and vault.
- Muscle strain. Higher Strength means strain builds slower.
Chapter 5
Weight: the hidden gate
Your body weight in kilograms sits in the Info panel. It changes what your body can do and what traits it has.
| Weight | Trait applied | Effect |
|---|---|---|
| 50 and under | Emaciated | Weaker, slower, less stamina. Near 35 kg, starvation damage. |
| 50 to 65 | Very Low Weight | Penalties. |
| 65 to 75 | Low Weight | Penalties. |
| 75 to 85 | None | The healthy band. |
| 85 to 100 | High Weight | Penalties. |
| 100 and up | Very High Weight (once called Obese) | Slower, less stamina, more strain. No constant health damage. |
Watch out: Fitness XP can be gated by weight
The game files confirm it. From Fitness 6, you get no Fitness XP while Emaciated, Very Low Weight or Very High Weight. From Fitness 9, High Weight blocks it too. Eat first, train second.
Secret: 75 to 85 is the target, not a bonus
Being in the band removes penalties. It does not add XP or speed. Stay there and forget about it.
Weight band and carry limit
Weight bands are from the table above. Carry limit is an estimate: 8 times a Strength multiplier, so about 12 at Strength 5 and 20 at Strength 10, before hunger, injury and trait changes.
Chapter 6
Nutrition and protein
Calories move the scale. Sandbox: Nutrition System Protein moves the Strength bar.
- Eat more calories than you burn and you gain weight. Fewer, and you lose. Exercise burns extra.
- Carbs and fats push weight up faster than protein.
- A high protein state gives a Strength XP bonus when you exercise. It gives nothing to Fitness.
- The Nutritionist trait shows the numbers. It is optional.
Secret: meat, fish, eggs before Strength day
Cook protein, then curl. See the Cooking, Fishing and Animal Care guides for the supply.
Chapter 7
The Exercise menu
Open the Health panel and press Exercise. Pick a move. Pick a duration. Train.
| Exercise | Needs | Trains | Body part |
|---|---|---|---|
| Squats | Nothing | Fitness | Legs |
| Sit-ups | Nothing | Fitness | Abs |
| Push-ups | Nothing | Strength | Arms and chest |
| Burpees | Nothing | Strength and Fitness, heavy | Legs, arms and chest |
| Barbell curls | Barbell | Strength, high modifier | Arms and chest |
| Dumbbell presses | Dumbbell | Strength, high modifier | Arms |
| Bicep curls | Dumbbell | Strength, high modifier | Arms |
- Free weights use higher XP modifiers, around 1.2 to 1.8. They are heavy. Keep them at base.
- Every rep drains endurance. Heavy exercises drain 1.3 times as much. You cannot start while carrying too much.
- Some sources say each level past 5 adds 10% exercise XP. In the game files, your level adds no extra exercise XP.
Watch out: never train exhausted, hurt or before a raid
At Excessive Exertion the game stops your workout. Exercise while bleeding is dangerous. Exercise the morning of a town clear leaves you stiff when it matters.
Chapter 8
Regularity and stiffness
Do the same move daily and your body gets used to it. Skip days and it forgets.
- Regularity is a percentage per exercise. It rises when you do the move often and falls when you stop.
- High regularity means less stiffness from that exercise.
- Stiffness is delayed soreness on the body part you trained. It shows up about 12 hours later. Stiff legs slow you down. Stiff arms make swings worse.
- Fitness Instructors start at 40 to 60% regularity. Firefighters 10 to 20%. Security Guards 7 to 12%.
Secret: rotate body parts
Squats one day, push-ups or curls the next. Stiffness never stacks on the same limb twice.
Chapter 9
Muscle strain: the other meter
Build 41 players get these confused. There are 2 soreness systems.
Exercise stiffness
From the Exercise menu only. Delayed. Reduced by regularity.
Muscle strain
From swinging weapons and heavy work like chopping and digging. Immediate. Reduced by Strength. Scaled by the sandbox Muscle Strain Factor. Sandbox: Muscle Strain Factor
Watch out: curls then axe day
Barbell curls in the morning and a fire axe in the afternoon light up both meters on the same arms. Train on quiet days.
Secret: stiffness builds faster when tired
Exercise stiffness doubles once you are Very Tired or worse. Sleep, then train.
Chapter 10
Passive XP: fighting, hauling, running
You do not have to be in the gym. Living hard trains both.
| Activity | Trains |
|---|---|
| Melee hits | Strength, plus Fitness while not overexerted |
| Running and sprinting | Fitness, and the Running skill too |
| Carrying more than half your capacity | Strength |
| Chopping trees | Strength |
Watch out: heavy load as a "hack"
Walking around at 60% capacity trains Strength slowly. Doing it during a fight gets you killed. Haul loot on purpose, at base, on safe days.
Watch out: hits while exhausted give no Fitness
The passive Fitness XP from hits needs a survivor who is not overexerted. Rest between packs.
Chapter 11
The traits you earn and lose
Your levels write your traits.
- Strength 6 to 8 gives Stout. Strength 9 and 10 give Strong. Strength 2 to 4 gives Weak, and 0 or 1 gives Puny.
- Fitness works the same with Athletic and Fit at the top, Unfit and Out of Shape at the bottom.
- Weight writes Emaciated, Very Low Weight, Low Weight, High Weight and Very High Weight.
Secret: train away a negative trait
Took Weak for the points? Level Strength and the trait disappears. The official wiki confirms it.
Chapter 12
Training plan: 5 to 10
A campaign, not a session. Months, not days.
Week 1: eat, weigh, squat
Get to 75 to 85 kg. Start 10 to 20 minutes of squats daily to build regularity. Push-ups every other day.
Weeks 2 to 4: rotate and haul
Squats daily. One Strength day with push-ups or looted dumbbells. Carry heavy loads on base days. Never train before a town strip.
Month 2 and on: weights and protein
Barbell and dumbbell moves in a safe upstairs room with a sheet rope exit. Cook protein before Strength days. Fight regularly, rested.
Watch out: the burpee marathon
An hour of burpees on day 1 gives stiffness, exhaustion and a dead survivor when the horde arrives. Fitness 3 characters should reroll Athletic next life, not grind burpees.
Level by level: Fitness and Strength
The best single thing to do at each level. Read the matching book first when one exists.
| Level | Do this for most of your XP | Why |
|---|---|---|
| 5 to 6 | Weight 75 to 85 kg. Squats daily, push-ups every other day | Regularity first |
| 6 to 7 | Add one Strength day with dumbbells and protein | Free weights use higher modifiers |
| 7 to 8 | Haul loot at 60% capacity on base days | Passive Strength |
| 8 to 9 | Barbell curls and fights on rested days | Rested hits add Fitness XP |
| 9 to 10 | Same, for months | Buy Athletic next life instead |
Home gym checklist
Room
Body
Plan
Your ticks are saved in this browser, on this device only.
Chapter 13
Tips, tricks and fixes
20 tips from the gym
Setup
- Buy Athletic. It is the best trait in the game.
- Fitness Instructor gives you skills and regularity.
- Haul a dumbbell and barbell to base once.
- A second-floor gym room with a sheet rope.
- Nutritionist if you like numbers.
Training
- 10 to 20 minutes, 1 or 2 moves.
- Squats daily for regularity.
- Rotate legs and arms.
- Protein before Strength, not Fitness.
- Never train tired, hurt or before a raid.
- Free weights for Strength, bodyweight for Fitness.
- Push-ups train Strength, not Fitness.
Living
- Stay 75 to 85 kg.
- Eat before you train.
- Fight rested for passive XP.
- Haul loot at base on safe days.
- Do not curl then axe.
- Sleep. Stiffness builds faster tired.
- Train away Weak and Unfit.
- Think in months.
Fix-it table
| Problem | Likely cause | Fix |
|---|---|---|
| Fitness will not move. | It is slow by design. | Daily squats, running, fights. Or Athletic next life. |
| I am losing levels. | Weeks with no training. The loss is slow. | Eat. Move. |
| My legs hurt the next day. | Stiffness. | Build regularity. Rotate parts. Rest. |
| My arms hurt in a fight. | Muscle strain. | Lighter weapon. Rest. Level Strength. |
| The Exercise menu is greyed out. | Exhausted, or too hurt. | Sleep. Heal. |
| Dumbbell stuck unusable. | A known interrupted-curl bug, fixed in 42.20. | Reproduce in vanilla. Report it. |
| I cannot carry anything. | Low Strength, hungry, hurt. | Eat. Heal. Level Strength. |
| Weight keeps climbing. | Too many calories. | Eat less. Exercise burns extra. |
| Protein did nothing for Fitness. | Correct. | Protein is a Strength bonus only. |
| Hits give no Fitness XP. | Overexerted. | Rest between packs. |
Chapter 14
Trainer's test
7 questions. Get them all right and you are in shape.
Chapter 15
Words and sources
Trainer's word list
- Endurance
- Stamina. Fitness slows how fast it drains.
- Encumbrance
- Carry capacity. Strength raises it.
- Regularity
- How used to an exercise your body is.
- Stiffness
- Next-day soreness from exercise.
- Muscle strain
- Immediate soreness from combat and heavy work.
- Healthy band
- 75 to 85 kg. No weight traits.
- High protein state
- A nutrition state that boosts Strength XP.
- Free weights
- Barbell and dumbbells.
How sure are we?
Every fact here was checked in September 2026. We checked the game files for version 42.21.0. Order of trust: the official wiki, then well-sourced fan guides, then player reports.
- Start at 5, no XP boost, what each skill affects, XP sources, regularity by job, heavy exercise drain, traits earned and lost. Confirmed on the official wiki. Some wiki values are stamped 42.18 or earlier.
- The Exercise list, free weight modifiers, and the 75 to 85 band. Fan guides for 42.19 and 42.20.4.
- Protein for Strength only, and the 2 soreness systems. Fan guides for 42.20.3.
- Fitness beats Strength. Player consensus.
- Trait costs. Athletic 10 and Fit 6 from a fan check of 42.20.4 files. May change.
- Checked against the game files (42.21.0): exercise XP and body parts, weight bands, carry weight, protein, level traits, trait and job costs. The wiki's 10% per level past 5 adds no XP in the files. Tiredness doubles exercise stiffness only from Very Tired.
Sources
- PZwiki (the official wiki): Fitness, Strength, Exercise, Skill
- PZfans fitness and strength guides for 42.19 and 42.20.4
- Gamers.wiki fitness and strength guide for 42.20.3
- Projectzomboid.wiki fitness and exercise guide
- Vortex Gaming fitness guide (Fitness over Strength)