One Rep Max Calculator: Epley Formula
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Understanding 1RM and Training Percentages

The one-repetition maximum (1RM) is the maximum weight one can lift in a single repetition for a given exercise. Understanding your 1RM is crucial for tailoring strength training programs to meet individual goals.

1RM Formulas

Two popular formulas for estimating 1RM are the Epley Formula and the Brzycki Formula, each providing a method to set training loads based on the weight you can lift for multiple reps.

Epley Formula

The Epley Formula is calculated as 1RM = weight lifted × (1 + reps / 30). It is widely used due to its simplicity and effectiveness in estimating 1RM from higher rep ranges.

Brzycki Formula

The Brzycki Formula is calculated as 1RM = weight lifted / (1.0278 - (0.0278 × reps)). This formula adjusts for the number of repetitions, offering a slightly more conservative estimate, especially useful for lower rep ranges.

Training Percentages of 1RM

Different training goals require lifting at various percentages of your 1RM:

  • Power: 75-90% of 1RM for 1-3 reps.
  • Strength: 85-100% of 1RM for 1-6 reps.
  • Hypertrophy: 67-85% of 1RM for 6-12 reps.
  • Endurance: Less than 67% of 1RM for more than 12 reps.

Practical Application

For example, if your bench press 1RM is estimated at 200 lbs using either formula, training for strength might involve lifting 170-200 lbs for 1-6 reps, while training for endurance could involve lifting less than 134 lbs for more than 12 reps.

Safety Note

Prioritize safety when testing 1RM or training at high intensities. Proper form, adequate warm-up, and the use of a spotter can help prevent injuries.

References for Further Reading

  • National Strength and Conditioning Association (NSCA) for guidelines on strength and conditioning.
  • "Essentials of Strength Training and Conditioning" by the NSCA for detailed insights into strength training methodologies.