Walk into any commercial gym and you'll find people doing the same exercises at roughly the same weights week after week, making little progress and wondering why. The missing ingredient is almost never effort. It's structure. Without knowing your one rep max (1RM) — the maximum weight you can lift for a single repetition with proper form — you can't calculate the training percentages that make progressive overload systematic rather than haphazard.
The good news is that you almost never need to actually attempt a genuine 1RM to know your number. Submaximal testing — using a weight you can lift 3-8 times — allows accurate 1RM estimation without the injury risk of maximal loading.
What Is One Rep Max and Why Does It Matter?
Your 1RM is the maximum load you can lift for one complete repetition with good technique. It's the reference point from which percentage-based training programmes calculate working weights. A programme calling for 5 sets of 5 at 80% of 1RM is only useful if you know your 1RM with reasonable accuracy.
Without this anchor, "heavy" is subjective. With it, every session has a specific, calculated challenge. Progressive overload — systematically increasing demand over time — becomes trackable and predictable rather than based on gut feel.
How to Calculate Your 1RM Without Testing It Directly
Several validated formulas estimate 1RM from submaximal lifts. The most commonly used are:
Epley Formula: 1RM = Weight × (1 + Reps ÷ 30)
Brzycki Formula: 1RM = Weight × 36 ÷ (37 − Reps)
For example: if you bench press 80kg for 6 reps, the Epley formula gives 1RM = 80 × (1 + 6/30) = 80 × 1.2 = 96kg.
These formulas are most accurate in the 3-8 rep range. Beyond 10 reps, the fatigue component introduces more variability and estimates become less reliable. For testing purposes, choose a weight you can lift 4-6 times with good form and apply the formula.
Using 1RM to Set Training Percentages
Different training percentages target different physiological adaptations:
50-60% of 1RM: Warm-up, technique practice, very high rep work (15-20+). Low neural demand, low fatigue.
65-75% of 1RM: Hypertrophy range at moderate reps (8-12). Primary muscle-building zone.
75-85% of 1RM: Strength-hypertrophy overlap. Heavy sets of 4-8 reps. Builds both strength and size.
85-95% of 1RM: Strength focus. Heavy sets of 1-5 reps. High neural demand, requires more recovery.
95-100% of 1RM: Maximum strength testing. Rarely trained; used for competition or periodic testing.
A standard beginner-to-intermediate strength programme might use 75-80% of 1RM for main lifts (5×5 or 3×5 sets), providing a stimulus that builds both strength and muscle without excessive fatigue.
Nutrition to Support Strength Training
Strength training creates a demand for protein — specifically to repair and build muscle tissue damaged by training. Research consistently supports a target of 1.6-2.2g of protein per kg of bodyweight for natural lifters focused on strength development.
Use our macro calculator to set protein and calorie targets aligned with your strength training goal. For muscle gain, a modest calorie surplus (200-300 above maintenance) with high protein supports muscle building without excessive fat accumulation. For strength maintenance during a cut, higher protein targets (approaching 2.4g/kg) help protect muscle mass in a deficit.
Aerobic Work and Strength Training
Strength training is predominantly anaerobic — short, intense efforts using immediate energy stores (ATP-PC system) and glycolytic pathways. Aerobic capacity still matters: better cardiovascular fitness improves recovery between sets, enhances work capacity, and supports overall health.
The key is managing the interference effect: excessive steady-state cardio, particularly on the same days as heavy lifting, can reduce strength training adaptations. Our calories burned calculator helps you account for cardio sessions in your energy balance — important when you're trying to maintain a precise calorie target for body composition goals alongside strength development.
Progressive Overload: The Principle Behind the Numbers
The mechanism of strength gain is progressive overload: consistently applying a training stimulus slightly greater than what the body has adapted to. Percentage-based training automates this by linking your working weights to your tested capacity and rebuilding from there.
As your 1RM increases (which it will, especially in the first months of structured training), re-test or recalculate periodically — every 4-8 weeks — and update your percentages accordingly. A 1RM figure from six months ago is no longer accurate and will underload your current capacity.
The British Weightlifting Association provides coaching resources and programming guidance for anyone looking to develop strength training technique alongside the numbers.
A Final Word on Actual Max Testing
Genuine 1RM testing — actually attempting your maximum — is not necessary for most recreational lifters and carries real injury risk if form breaks down under maximal load. Reserve actual max attempts for experienced lifters with sound technique, preferably under supervision. For everyone else, submaximal estimation with the formulas above gives you everything you need to programme effectively, safely.