Fitness Language Decoded: From Reps to RIR Without the Confusion

Fitness terms can feel like another language. They're mostly simple ideas with shorthand names. This guide translates the essential ones.

#Reps, Sets, and Effort

Rep (Repetition): One complete movement - one squat equals one rep.

Set: A group of reps done without stopping. Written as 3x10 (3 sets of 10 reps).

RIR (Reps in Reserve): How many more reps you could still do. RIR 3 means you stop when you could do 3 more. RIR 0 means muscle failure.

RPE (Rate of Perceived Exertion): How hard it feels on a 1-10 scale. RPE 7-8 is hard effort; you can only speak in short phrases.

1RM: The maximum weight you can lift once - used to calculate training percentages.

#Movement Types

Compound exercises work multiple muscle groups and joints at once - squats, push-ups, deadlifts. Best bang for your buck.

Isolation exercises target one muscle group - bicep curls, leg extensions. Good for targeting weak points.

#Rep Phases

• Eccentric: The lowering/lengthening phase (most muscle damage occurs here)
• Isometric: Holding still under tension
• Concentric: The lifting/shortening phase

#Cardio Terms

LISS: Low Intensity Steady State - easy, sustainable pace you can maintain.

HIIT: High Intensity Interval Training - short bursts of hard work followed by rest.

#Macronutrients

The three macros and their calorie content:

• Protein: 4 calories per gram (builds/repairs muscle)
• Carbs: 4 calories per gram (primary energy)
• Fats: 9 calories per gram (hormone production)

#Recovery Terms

DOMS (Delayed Onset Muscle Soreness): The soreness 24-48 hours after exercise. It is normal and not an injury - it decreases as you adapt.

Active Recovery: Light movement on rest days. Not another workout.

Deload Week: Planned easy week at 50% normal intensity, usually every 4-6 weeks.

#Key Phrases Decoded

• Mind-muscle connection: Focusing on feeling the target muscle work during an exercise
• "What's your split?" = How do you divide your training days? (Upper/Lower, Push/Pull/Legs, Full Body)
• "To failure" = Exercise until you can't do another rep with good form
• AMRAP = As Many Reps (or Rounds) As Possible
• Neutral spine = Natural back position, not arched or rounded

With these terms, you can read programs, talk to trainers, and join gym conversations without feeling lost.