The Language of Fitness: A Plain-English Glossary of Common Exercise Terms

Rep (Repetition)

One complete performance of a single exercise movement — for example, lowering and raising a dumbbell once during a bicep curl. Reps are the smallest unit of a workout.

Set

A group of consecutive reps performed without stopping. If a plan says '3 sets of 10 squats,' you do 10 squats, rest, then repeat that group two more times.

1RM (One-Rep Max)

The maximum weight you can lift for exactly one rep of a given exercise with proper form. It's used as a reference point to calculate training loads — for instance, working at '75% of your 1RM.'

RPE (Rate of Perceived Exertion)

A self-reported scale — typically 1 to 10 — that describes how hard an effort feels. An RPE of 6 might feel moderately challenging; an RPE of 9 means you could do only one or two more reps before failing.

HIIT (High-Intensity Interval Training)

A training format that alternates short bursts of intense effort with brief recovery periods. The intervals and ratios vary widely; the defining feature is the contrast between high-effort and low-effort phases.

Compound Movement

An exercise that works multiple muscle groups and joints simultaneously — such as a squat, deadlift, or push-up. Compound movements are generally efficient for building overall strength.

Isolation Exercise

An exercise that targets a single muscle group by moving only one joint — for example, a bicep curl or leg extension. Often used to address specific weaknesses or imbalances.

Progressive Overload

The principle of gradually increasing training demands over time so the body continues to adapt and improve. This can mean adding weight, reps, sets, or reducing rest periods.

DOMS (Delayed Onset Muscle Soreness)

The muscle soreness that typically peaks 24–72 hours after an unfamiliar or particularly demanding workout. DOMS is a normal response to physical stress, not a sign of injury.

Superset

Performing two exercises back-to-back with little or no rest between them. Supersets can target the same muscle group or opposing ones and are often used to increase workout density.

Eccentric Phase

The portion of a movement where the muscle lengthens under tension — such as slowly lowering a weight during a bicep curl. Controlled eccentric movement is associated with significant strength gains.

Active Recovery

Low-intensity movement — such as walking, light stretching, or gentle cycling — done on rest days to promote circulation and reduce soreness without adding significant training stress.