1. What is the ExRx 1RM Equation?

The ExRx (Exercise Prescription) 1RM equation estimates your one-repetition maximum (the maximum weight you can lift for one repetition) based on the weight you can lift for multiple repetitions. This allows you to estimate your maximum strength without actually attempting a 1RM lift.

2. How Does the Calculator Work?

The calculator uses the ExRx equation:

Where:

• \( w \) — Weight lifted (kg)
• \( r \) — Number of repetitions performed

Explanation: The equation accounts for the inverse relationship between the weight you can lift and the number of repetitions you can perform with that weight.

3. Importance of 1RM Calculation

Details: Knowing your 1RM is important for designing strength training programs, tracking progress, and determining appropriate training loads for different goals (strength, hypertrophy, endurance).

4. Using the Calculator

Tips: Enter the maximum weight you can lift for a given number of repetitions (between 1 and 36 reps). For most accurate results, use a weight you can lift for 2-10 reps.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this 1RM estimation?
A: The ExRx formula provides a reasonably accurate estimate for most people, especially in the 2-10 rep range. Individual variations in muscle fiber composition can affect accuracy.

Q2: Why shouldn't I test my actual 1RM?
A: Testing actual 1RM requires proper technique and can be risky without supervision. Estimation formulas allow safer strength assessment.

Q3: Can I use this for all exercises?
A: This works best for compound exercises like bench press, squat, and deadlift. It may be less accurate for isolation exercises.

Q4: How often should I recalculate my 1RM?
A: Recalculate every 4-8 weeks as your strength changes. More frequent testing isn't necessary as strength gains occur gradually.

Q5: Are there other 1RM formulas?
A: Yes, other popular formulas include Brzycki, Epley, and Lombardi. Different formulas may work better for different individuals or rep ranges.