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5 Ways to Find a 1 Rep Max (1RM) for Strength Training

Building strength and putting on muscle is one of the best ways to reduce injury risk and build resilience—especially for athletes and active individuals. A well-structured strength training program relies on progressive overload, which means lifting enough weight to create adaptation. Many programs determine load based on a 1 rep max (1RM)—the maximum amount of weight an individual can lift for a single repetition.

A common strength prescription is 5 sets of 5 at 80% of your 1RM. But before lifting at that percentage, you need to determine your true or estimated 1 rep max. Below, we outline five different methods to calculate your 1RM, whether you’re an experienced lifter or new to heavy lifting.

A woman in a gym prepares to lift a barbell loaded with weights. She is wearing gym attire and focused on adjusting her grip on the barbell for peak performance. Dim lighting with bright windows in

1. Find a True 1 Rep Max (For Experienced Lifters)

  • How it works: Gradually increase weight until you reach your absolute max for a single repetition.
  • Best for: Experienced lifters with proper technique and access to a spotter.
  • Downside: Time-consuming and higher injury risk if not performed correctly.
  • Example: If you bench press 200 lbs and fail at 205 lbs, your 1RM is 200 lbs.

💡 Tip: If you’re recovering from an injury or seeking a safer way to regain strength, consider working with a professional. Learn how physical therapy in Madison can help with performance-based rehabilitation.


 

2. Establish a 5-Rep or 10-Rep Max (Safer Alternative)

  • How it works: Lift a weight for multiple repetitions (e.g., 5 reps or 10 reps) instead of a single rep max.
  • Conversion guide:
    • 5 rep max ≈ 90% of 1RM
    • 10 rep max ≈ 75% of 1RM
  • Best for: Those who want to avoid maximum load but still estimate strength levels.
  • Example: If you squat 200 lbs for 5 reps, your estimated 1RM is ≈ 222 lbs.

💡 Tip: This method is excellent for endurance athletes and runners who incorporate strength training to reduce injury risk and improve power output.


 

3. Use a 1 Rep Max Calculator (Quick & Easy Method)

  • How it works: Perform as many reps as possible with a moderate weight and use a 1RM calculator to estimate your max.
  • Example formula:
    • 1RM = (Weight × Reps × 0.0333) + Weight
  • Best for: Those looking for a fast, low-risk estimate.
  • Example: If you deadlift 160 lbs for 12 reps, your estimated 1RM is 224 lbs.

💡 Pro Tip: You can use online 1RM calculators or strength-based apps to track progress.


 

4. Rate of Perceived Exertion (RPE) Method (Subjective Scaling)

  • How it works: Rate your effort on a scale from 1-10 after each lift.
  • RPE guide:
    • 10/10 = Maximum effort (true 1RM)
    • 8/10 = 80% of 1RM (heavy, but not failure)
    • 6/10 = 60% of 1RM (moderate difficulty)
  • Best for: Lifters who prefer an intuitive approach without strict calculations.

💡 Tip: RPE-based training works well for injury recovery or for adjusting workouts based on fatigue, recovery, and performance.


 

5. Repetitions in Reserve (RIR) Method (Listening to Your Body)

  • How it works: After completing a set, estimate how many reps you had left in the tank before failure.
  • Conversion guide:
    • 0 RIR = 1 Rep Max (No more reps left before failure)
    • 3 RIR = About 80% of 1RM
    • 5 RIR = About 60% of 1RM
  • Example: If you complete 5 squats but feel like you could have done 4 more, your RIR is 4. This corresponds to an RPE of 6/10 (moderate effort).

💡 Pro Tip: RIR is great for injury prevention because it helps athletes avoid overtraining and unnecessary fatigue.

Table displaying "description of perceived exertion (rpe) and repetition in reserve (rir)" with ratings 0-10. The RPE scale spans from "extremely easy" to "peak

Putting It All Together: Maximizing Strength Training for Performance

Once you’ve determined your 1 rep max, you can use it to optimize your strength training program. The more accurate your max estimates, the better your training progressions and injury prevention strategies will be.

If you’re a runner, endurance athlete, or active individual looking to integrate strength training into your routine, we recommend working with a physical therapist to optimize your form and reduce injury risk. Learn more about how physical therapy in Madison can help you train smarter, recover faster, and perform better.

Happy lifting! 💪 

 

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Our Mission: Strength & Resilience for Active Adults

 

At Peak Endurance Performance & Physical Therapy, we help active individuals in Madison get back to the activities they love without pain or limitations. Whether you’re a runner, weightlifter, CrossFit athlete, or weekend warrior, we’re here to support you on your journey.

If you’re ready to train smarter, recover faster, and move without limitations, reach out today!