The Fitness Terms Glossary Every New Exerciser Should Bookmark
From HIIT to RPE to compound movements — a plain-language reference to the fitness terms you'll encounter most.
Photo: SaverSteals.com editorial
—— In This Article
Why Fitness Jargon Matters for Beginners
Walking into a gym — or opening a workout app — for the first time can feel like entering a foreign country. Trainers cue you to "engage your core," programs promise "hypertrophy gains," and class schedules list HIIT, RPE, and 1RM without explanation. Understanding what these terms actually mean isn't just academic — it directly affects how safely and effectively you train.
This reference glossary covers the words and abbreviations you'll encounter most often, organized so you can look up what you need quickly. For a deeper look at how common fitness beliefs can lead you astray, see our companion piece on exercise myths that keep people from making real progress.
| Training volume unit | Sets × Reps × Load (Standard exercise science convention) |
| RPE scale range | 1 (very light) to 10 (maximal effort) (Adapted Borg CR10 scale) |
| Hypertrophy rep range | Approx. 6–20 reps per set (NSCA Essentials of Strength Training, general guideline) |
| Recommended warm-up duration | 5–10 minutes of light activity (American College of Sports Medicine general guidance) |
| Progressive overload principle | Increase stress gradually over time (Foundational exercise science principle) |
Core Fitness Terms Defined
The glossary below covers foundational vocabulary across training structure, physiology, and effort measurement. Bookmark it and return whenever an unfamiliar term appears in your program.
Repetition (Rep)
One complete execution of an exercise movement — for example, one full squat from standing to depth and back up. Reps are the smallest unit of exercise volume in strength training.
Set
A group of consecutive repetitions performed without rest. A program might prescribe "3 sets of 10 reps," meaning you do 10 reps, rest, and repeat that sequence twice more.
HIIT
High-Intensity Interval Training. A workout structure that alternates short bursts of near-maximal effort with recovery periods. Research consistently shows HIIT improves cardiovascular fitness efficiently, though it requires adequate recovery between sessions.
RPE
Rate of Perceived Exertion. A self-reported 1–10 scale (or the original Borg 6–20 scale) used to describe how hard an effort feels. An RPE of 6 feels easy; an RPE of 9 means you could manage only one or two more reps or seconds.
1RM
One-Rep Maximum. The heaviest load you can lift for exactly one full repetition with good form. It is used as a benchmark for programming — many programs prescribe loads as a percentage of your 1RM.
Compound Movement
An exercise that recruits multiple muscle groups across more than one joint simultaneously. Squats, deadlifts, bench press, and pull-ups are classic examples. Compound moves are generally prioritized in programs because they develop strength broadly and efficiently.
Isolation Exercise
An exercise that targets a single muscle group by moving primarily one joint — for example, a bicep curl. Isolation work is often used to address weaknesses or build definition after compound movements are programmed.
Hypertrophy
The increase in muscle cell size that results from consistent resistance training and adequate protein intake. Hypertrophy-focused programs typically use moderate loads with higher rep ranges (roughly 6–20 reps per set) and controlled rest periods.
Progressive Overload
The principle of gradually increasing training stress over time — through more weight, reps, sets, or reduced rest — to continue driving adaptation. Without progressive overload, fitness tends to plateau.
Aerobic vs. Anaerobic
Aerobic exercise uses oxygen as the primary energy source and can be sustained for extended periods (e.g., jogging, cycling). Anaerobic exercise relies on energy systems that don't require oxygen and is typically brief and intense (e.g., sprinting, heavy lifting). Both systems contribute to overall fitness.
Warm-Up and Cool-Down
A warm-up is light activity and dynamic movement performed before training to gradually raise heart rate and prepare joints and muscles. A cool-down consists of easier movement and static stretching after exercise to support recovery and reduce post-workout stiffness.
Rest Period
The planned pause between sets or intervals. Rest period length affects training outcomes: shorter rests (30–60 seconds) tend to emphasize endurance and metabolic stress, while longer rests (2–5 minutes) better support strength and power development.
This article provides general fitness education and is not a substitute for guidance from a qualified personal trainer, physical therapist, or physician. If you have an existing injury or health condition, consult a healthcare professional before beginning a new exercise program.
Health Editorial Team
Health Editorial Team is the collective byline for our editorial team and contributor network. Articles published under this byline or an editorial pen name are researched, written, and reviewed according to our editorial standards for clarity, consistency, and independence before publication.
View author profile