One-Rep Max & VO2 Max Explained

What Is One-Rep Max (1RM)?

Your one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is the gold standard for measuring absolute strength and is used by coaches, athletes, and recreational lifters to design training programs, track progress, and set training loads.

Directly testing your 1RM involves loading a barbell to the heaviest weight you can manage for one clean rep. However, this carries injury risk, especially for beginners. That is why most people estimate their 1RM using submaximal loads — lifting a lighter weight for multiple reps and plugging the numbers into a formula.

Popular 1RM Formulas

Several validated formulas exist for estimating 1RM. The two most widely used are:

• Brzycki Formula: 1RM = weight × (36 / (37 - reps))
  Best for rep ranges of 1–10. Tends to be slightly conservative.
• Epley Formula: 1RM = weight × (1 + reps / 30)
  Slightly more generous at higher rep ranges. Works well for 1–15 reps.

For example, if you bench press 185 lbs for 6 reps, the Brzycki formula estimates your 1RM at approximately 214 lbs, while the Epley formula gives about 222 lbs. Most calculators average multiple formulas for a more reliable estimate.

Using 1RM for Training Percentages

Once you know your estimated 1RM, you can program your training using percentages:

• 90–100% of 1RM: Maximum strength (1–3 reps)
• 75–85% of 1RM: Strength and hypertrophy (4–8 reps)
• 65–75% of 1RM: Hypertrophy focus (8–12 reps)
• 50–65% of 1RM: Muscular endurance (12–20 reps)
• 30–50% of 1RM: Speed and power work, warm-ups

This percentage-based approach removes guesswork from your programming and ensures progressive overload over time.

What Is VO2 Max?

VO2 max (maximal oxygen uptake) is the maximum rate at which your body can consume oxygen during intense exercise. It is measured in milliliters of oxygen per kilogram of body weight per minute (mL/kg/min) and is widely considered the best single indicator of cardiovascular fitness and aerobic endurance.

A higher VO2 max means your heart, lungs, and muscles are more efficient at transporting and using oxygen. Elite endurance athletes typically have VO2 max values of 70–85 mL/kg/min, while the average untrained adult ranges from 30–45 mL/kg/min.

The Cooper Test Protocol

The Cooper 12-Minute Run Test is one of the simplest and most accessible ways to estimate VO2 max without laboratory equipment. Here is how it works:

• Warm up for 5–10 minutes with light jogging and dynamic stretches.
• Run as far as you can in exactly 12 minutes on a flat surface (track is ideal).
• Record the total distance covered in meters.
• Apply the formula: VO2 max = (distance in meters - 504.9) / 44.73

For example, if you run 2,400 meters in 12 minutes, your estimated VO2 max is approximately 42.4 mL/kg/min, which falls in the “good” range for most age groups.

VO2 Max Fitness Classifications

VO2 max values are typically interpreted relative to age and sex. Here are general ranges for men aged 20–39:

• Superior: 52+ mL/kg/min
• Excellent: 47–51 mL/kg/min
• Good: 42–46 mL/kg/min
• Fair: 37–41 mL/kg/min
• Poor: Below 37 mL/kg/min

Women’s values are generally 10–15% lower at each classification level due to physiological differences in hemoglobin concentration and body composition.

How to Improve Both Metrics

Improving your 1RM requires progressive overload — gradually increasing the weight, volume, or intensity of your strength training over time. Focus on compound lifts (squat, deadlift, bench press, overhead press), train in the 3–6 rep range for strength, eat adequate protein (1.6–2.2 g/kg body weight), and ensure proper recovery with 7–9 hours of sleep.

Improving your VO2 max requires consistent aerobic training, with high-intensity interval training (HIIT) being the most time-efficient method. Research shows that 4×4 minute intervals at 90–95% of max heart rate with 3-minute recovery periods, performed 3 times per week, can improve VO2 max by 5–10% in 8–12 weeks. Steady-state cardio at 60–75% of max heart rate also builds aerobic base when performed for 30–60 minutes.

For a comprehensive view of your fitness, combine these metrics with your BMI and daily calorie needs. You can also check your cardiovascular fitness level with the VO2 Max Calculator.