| VO2 max unit of measure | ml/kg/min (millilitres of oxygen per kilogram of body weight per minute) (American College of Sports Medicine) |
| BMR share of daily calorie burn | Approximately 60–75% of total daily energy expenditure (General exercise physiology consensus) |
| Recommended weekly aerobic activity (adults) | At least 150 minutes of moderate-intensity activity (U.S. Department of Health and Human Services Physical Activity Guidelines) |
| Muscle fibre types | Type I (slow-twitch, endurance) and Type II (fast-twitch, power) (Established exercise physiology) |
| Recovery window post-exercise | Muscle protein synthesis is elevated for 24–48 hours after resistance training (Journal of the International Society of Sports Nutrition) |
Why Health Vocabulary Matters
Walk into a gym, read a fitness app, or skim a doctor's discharge summary, and you'll encounter terms that can feel like a second language. Words like aerobic threshold, homeostasis, or periodization aren't reserved for scientists — they appear in mainstream wellness content every day. Yet most of us were never given clear definitions.
This reference guide decodes the physical health vocabulary you're most likely to encounter, whether you're researching exercise science, talking with a healthcare provider, or simply trying to understand a nutrition label. Each definition below is grounded in established health and physiology principles. For decisions about your own health, always consult a qualified healthcare professional — this guide is general education, not medical advice.
If you're also navigating the language of mental wellness, our plain-language mental health glossary covers that territory in the same approachable format. And for building the daily routines that put these concepts into practice, the Healthy Habits hub is a useful companion.
VO2 Max
The maximum volume of oxygen the body can use during intense aerobic exercise, expressed in ml/kg/min. It is a standard measure of cardiovascular fitness and endurance capacity.
Progressive Overload
A training principle that involves gradually increasing exercise demands — load, volume, or intensity — over time so the body continues to adapt and improve rather than plateau.
Basal Metabolic Rate (BMR)
The number of calories the body burns at complete rest to sustain essential functions such as breathing and circulation. BMR accounts for the largest portion of total daily energy expenditure for most people.
EPOC
Excess Post-Exercise Oxygen Consumption — the elevated oxygen intake that occurs after exercise as the body returns to its resting state. This process requires additional energy and is sometimes called the 'afterburn effect.'
Aerobic Exercise
Physical activity that relies on oxygen to produce energy and can be sustained for extended periods. Examples include brisk walking, jogging, swimming, and cycling.
Anaerobic Exercise
High-intensity activity where energy demand exceeds the body's ability to deliver oxygen, so stored energy sources are used instead. Sprinting and heavy resistance training are typical examples.
Body Composition
The proportion of fat mass versus lean mass (muscle, bone, and water) in the body. It provides a more complete picture of physical health than body weight alone.
Homeostasis
The body's tendency to maintain stable internal conditions — such as temperature, blood pH, and blood sugar — despite changes in the external environment. Many physical health interventions work by supporting or restoring homeostasis.
Periodization
A structured approach to training that cycles through phases of varying intensity, volume, and focus over weeks or months to optimize performance and reduce injury risk.
Active Recovery
Low-intensity movement performed on rest days — such as walking or gentle stretching — intended to promote blood flow, reduce muscle soreness, and support repair without adding training stress.
Anabolic
Describing metabolic processes that build and repair body tissues, such as muscle protein synthesis after resistance training. Anabolic states are driven by adequate nutrition and recovery.
Catabolic
Describing metabolic processes that break down complex molecules into simpler ones for energy, such as breaking down fat or muscle during prolonged exercise or caloric deficit.
Core Physical Health Terms Explained
The following definitions cover the terms that appear most frequently across fitness, exercise science, and general health contexts. They are grouped loosely by theme for easier scanning.
| VO2 max unit of measure | ml/kg/min (millilitres of oxygen per kilogram of body weight per minute) (American College of Sports Medicine) |
| BMR share of daily calorie burn | Approximately 60–75% of total daily energy expenditure (General exercise physiology consensus) |
| Recommended weekly aerobic activity (adults) | At least 150 minutes of moderate-intensity activity (U.S. Department of Health and Human Services Physical Activity Guidelines) |
| Muscle fibre types | Type I (slow-twitch, endurance) and Type II (fast-twitch, power) (Established exercise physiology) |
| Recovery window post-exercise | Muscle protein synthesis is elevated for 24–48 hours after resistance training (Journal of the International Society of Sports Nutrition) |
Exercise Science
VO2 max refers to the maximum rate at which your body can consume oxygen during intense exercise. It is widely used as a marker of cardiovascular fitness — a higher VO2 max generally indicates a more efficient heart and lungs. It is measured in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min).
Progressive overload is the principle of gradually increasing the demands placed on the body — through greater weight, more repetitions, or reduced rest — so that muscles and cardiovascular systems continue to adapt. Without it, improvement tends to plateau.
EPOC (Excess Post-Exercise Oxygen Consumption), sometimes called the "afterburn effect," describes the elevated oxygen intake that continues after a workout ends. The body uses this extra oxygen to restore itself to its resting state, which requires additional energy expenditure.
Metabolism and Body Composition
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic functions — breathing, circulation, and cell repair. BMR is influenced by age, sex, body size, and lean muscle mass.
Body composition describes the ratio of fat mass to lean mass (muscle, bone, and water) in the body. It is considered a more nuanced health indicator than body weight alone, since two people at the same weight can have very different health profiles.
Anabolic and catabolic are two opposing metabolic states. Anabolic processes build up tissues (e.g., muscle growth after resistance training); catabolic processes break them down (e.g., using stored fat for energy). Both are normal and necessary.
Cardiovascular and Recovery Terms
Aerobic exercise uses oxygen as the primary fuel source and can be sustained over time — walking, cycling, and swimming are common examples. Anaerobic exercise is performed at high intensity for short bursts, when the body cannot deliver oxygen fast enough and relies on stored energy instead — sprinting and heavy lifting fall into this category.
Active recovery involves low-intensity movement on rest days — gentle walking or stretching — to promote circulation and reduce muscle soreness without adding stress to the body.
This article is for informational purposes only and is not medical advice. Always consult a qualified healthcare professional before making changes to your exercise or health routine.