Formula, in Strength Training

Junk Volume Threshold Formula

Junk volume is training volume above your Maximum Adaptive Volume (MAV) that produces no further hypertrophy or strength gain — only fatigue. Schoenfeld's 2017 meta-analysis pegs the dose-response: muscle growth tracks weekly set count up to a per-muscle ceiling. Above that ceiling, additional sets cost more recovery than they add. The formula sets a threshold per muscle group based on training age, intensity, and recovery quality.

5 variables. Published May 14, 2026. By AI Fit Hub.

Education, not medical advice. The result comes only from the published formula and your inputs. How we check our formulas.

Formula

junk_volume_threshold = MAV × intensity_factor × recovery_factor
   MAV ≈ 12 + 0.5 × (training_age_years − 1)   sets/muscle/week
   intensity_factor: 1.0 (RPE 7-8), 0.8 (RPE 9-10)
   recovery_factor: 1.0 (sleep ≥7h, low life stress), 0.7 (poor recovery)

Variables

junk_volume_threshold

Sets above which additional volume is junk

Per-muscle weekly working-set count. Sets beyond this produce no measurable hypertrophy and increase joint/CNS fatigue.

MAV

Maximum Adaptive Volume

Per-muscle weekly set ceiling for hypertrophy. Beginners: 10-12 sets. Intermediates: 14-18 sets. Advanced: 20-25 sets. Above MAV is MRV (Maximum Recoverable Volume — survive but don't progress).

training_age_years

Years of consistent training

Years of bodybuilding-style training, not total gym attendance. Stop-and-start counters reset to 80% of prior level.

intensity_factor

Set intensity multiplier

Sets close to failure (RPE 9-10) deplete more glycogen and accumulate more fatigue per set. Lower MAV by 20% when most sets are high-RPE.

recovery_factor

Recovery quality multiplier

Poor sleep, high life stress, or undereating all lower the recoverable volume ceiling. A 6h-sleep, dieting lifter has 30% less MAV than the same lifter eating + sleeping well.

Step by step

1

Determine training age (years of consistent lifting).

5 years of consistent training.
2

Compute base MAV.

MAV = 12 + 0.5 × (5 − 1) = 14 sets/muscle/week.
3

Apply intensity factor. Most sets at RPE 7-8 = 1.0. Most at RPE 9-10 = 0.8.

Training mostly RPE 8: factor 1.0. → MAV stays 14.
4

Apply recovery factor. Good sleep + adequate calories = 1.0. Cutting + 6h sleep = 0.7.

Maintenance phase, 7h sleep: factor 1.0. Junk threshold = 14 × 1.0 × 1.0 = 14 sets/week per muscle.
5

Compare actual weekly volume per muscle group. Anything above threshold is junk.

Logging shows 22 sets/week for chest. Threshold 14. → 8 sets are junk. Cut to ~16 to leave a stimulus margin.

Worked example

5-year intermediate lifter, currently doing 22 sets chest/week at RPE 8 in maintenance

Training age

5 years

Most sets at RPE

7-8 (intensity_factor = 1.0)

Recovery state

Good (recovery_factor = 1.0)

Current chest volume

22 sets/week

MAV = 12 + 0.5 × (5 − 1) = 14 sets/muscle/week Junk threshold = 14 × 1.0 × 1.0 = 14 sets Current 22 sets − 14 threshold = 8 junk sets

8 chest sets/week are likely producing zero additional hypertrophy while costing ~30% more recovery time. Cut chest from 22 to 14-16 sets — reallocate the saved volume to lagging muscle groups (legs, back), or take an extra rest day.

Common variations

Schoenfeld 2017: dose-response slope flattens above 10 sets/muscle/week; some growth continues to 20+ sets in trained subjects but diminishing returns are steep.

RP MEV/MAV/MRV framework: MEV (Minimum Effective Volume) ~6-8 sets, MAV (Maximum Adaptive Volume) ~12-16 sets, MRV (Maximum Recoverable Volume) ~20-25 sets. Each muscle group has its own range.

Frequency adjustment: same weekly volume split across 3 sessions outperforms 1 session by ~15% (Schoenfeld 2016). Junk volume threshold scales with frequency — 14 sets split into 2x7 sessions provides more stimulus than 1x14.

Periodized variation: volume can spike 30-50% above MAV for 1-2 weeks (overload) before deload, without long-term junk-volume penalty. Helms et al. 2018 — strategic overreach.

Run the numbers next

Strength Workout Volume Calculator
Calculate total training volume and compare against optimal ranges per muscle group.
Strength Progressive Overload Planner
Project lifting progression with weekly overload and planned deload cycles.
Recovery HRV Deload Trigger
Decide whether to deload from 7 days of HRV vs 30-day baseline using the Plews 2014 method.

Sources

Schoenfeld, Ogborn & Krieger (2017). Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis. , Journal of Sports Sciences — foundational volume-hypertrophy meta-analysis
Schoenfeld, Ogborn & Krieger (2016). Effects of resistance training frequency on measures of muscle hypertrophy: A systematic review and meta-analysis. , Sports Medicine — frequency effects on volume distribution
Helms, Cronin, Storey & Zourdos (2017). RPE and velocity relationships for the back squat, bench press, and deadlift in powerlifters. , Journal of Strength & Conditioning Research — RPE calibration
Israetel et al. (Renaissance Periodization, 2017). Scientific Principles of Hypertrophy Training. , RP — MEV/MAV/MRV framework with practical application