The traditional 5-component model of health-related fitness is built around cardiorespiratory endurance, muscular strength, muscular endurance, flexibility and body composition. The American College of Sports Medicine identifies these five areas in its standard health-related fitness model.
The source cited here also refers to an updated ACSM framework published in August 2026. That framework groups some areas differently, but the traditional five remain the usual answer for school assignments, introductory courses and general fitness explanations.
The 5 Components of Fitness at a Glance
| Fitness component | What it measures | Examples |
|---|---|---|
| Cardiorespiratory endurance | How well the heart, lungs and blood vessels deliver oxygen during sustained activity | Running, cycling, swimming |
| Muscular strength | The maximum force a muscle or muscle group can produce | Weightlifting, heavy resistance training |
| Muscular endurance | How long a muscle can work repeatedly without excessive fatigue | Planks, bodyweight squats, rowing |
| Flexibility | The range of motion available at a joint | Stretching, yoga, mobility exercises |
| Body composition | The relative amounts of fat, muscle, bone and other tissues in the body | Skinfold measurements, bioelectrical impedance, scans |
1. Cardiorespiratory Endurance
Cardiorespiratory endurance is the ability of the heart, lungs and circulatory system to deliver oxygen during sustained physical activity. It is also called cardiovascular endurance or aerobic fitness.
Brisk walking, jogging, cycling, swimming, dancing and hiking can all improve this component. Someone with good cardiorespiratory endurance can usually stay active for longer before becoming short of breath or overly fatigued.
2. Muscular Strength
Muscular strength is the maximum force that a muscle or muscle group can produce in one effort.
A one-repetition deadlift, a heavy press or the force used to move a heavy object can all relate to muscular strength. Training methods include free weights, resistance machines, kettlebells, bodyweight exercises and resistance bands.
Strength supports everyday movements such as lifting, carrying, pushing and pulling.
3. Muscular Endurance
Muscular endurance is the ability of a muscle or muscle group to keep working repeatedly or for an extended period without excessive fatigue.
Holding a plank, completing repeated push-ups or rowing for several minutes tests muscular endurance. Cycling uphill and performing sets of bodyweight squats can also train it.
Muscular strength and muscular endurance are related, but they measure different abilities. Strength concerns the greatest force you can produce. Endurance concerns how long or how often your muscles can keep working.
4. Flexibility
Flexibility is the available range of motion at a joint.
Flexibility differs between joints and between individuals. Static stretching, dynamic stretching, yoga, Pilates and mobility drills can help maintain or improve it.
Good flexibility can make reaching, bending, squatting and rotating easier. Stretching should be controlled and should not force a joint into a painful position.
5. Body Composition
Body composition describes the relative amounts of fat, muscle, bone and other tissues in the body.
Body composition is different from body weight. Two people can weigh the same while having different proportions of muscle and fat.
Resistance training, aerobic exercise, nutrition, sleep, age and genetics can all affect body composition. Methods such as skinfold measurements, bioelectrical impedance and scans can estimate it.
Body composition is only one part of fitness. It should not be used on its own to judge a person's health, performance or physical ability.
How to Improve All 5 Components of Fitness
A balanced fitness routine can address all five areas:
- Cardiorespiratory endurance: Do regular aerobic activity such as walking, running, cycling or swimming.
- Muscular strength: Use challenging resistance exercises with safe, controlled technique.
- Muscular endurance: Use lighter resistance, circuits or sustained bodyweight exercises.
- Flexibility: Include regular stretching and mobility work.
- Body composition: Combine physical activity with sustainable nutrition and adequate recovery.
Many activities train more than one component. Circuit training, for example, can develop cardiorespiratory endurance, muscular strength and muscular endurance in the same session.
Traditional Versus Newer Fitness Models
The traditional model includes:
- Cardiorespiratory endurance
- Muscular strength
- Muscular endurance
- Flexibility
- Body composition
The ACSM framework cited in the source, published in August 2026, groups strength, endurance and power under muscular fitness. It also includes neuromotor fitness, which covers abilities such as balance, agility and gait speed.
If you need the conventional answer to "What are the 5 components of fitness?", use cardiorespiratory endurance, muscular strength, muscular endurance, flexibility and body composition.