EVIDENCE LIBRARY
Built from research.
Applied with context.
Registry version 1.1 · Updated September 6, 2026
HULL translates resistance-training research into understandable planning, progression, and coaching guidance. This registry explains the evidence behind those decisions and the limits of what the app claims.
A study informs a product decision; it does not make that decision universally correct for every person. HULL combines published evidence with training goals, experience, available equipment, completed workout history, and user preference.
You Don’t Have to Train to Failure to Grow
Recent research in resistance-trained adults found that stopping sets with approximately 1–3 repetitions in reserve (RIR) produced similar gains in muscle size and strength to routinely training to momentary muscular failure.
Train hard enough to create the stimulus. Manage fatigue so you can keep progressing.
HULL generally programs hard working sets close to failure without requiring failure on every set. Failure training is not treated as harmful or ineffective—it remains an optional strategy, not a requirement.
HYPERTROPHY · STRENGTH · RIR
Leg Extension: 1–3 RIR vs. Failure
After eight weeks, resistance-trained men and women showed essentially similar knee-extensor hypertrophy and strength adaptations when sets ended at approximately 1–3 RIR or at momentary muscular failure.
How HULL applies it: Prescribe challenging working sets near failure while managing fatigue across the session and week.
HYPERTROPHY · STRENGTH · FATIGUE MANAGEMENT
Elbow Flexors: 1–3 RIR vs. Failure
Resistance-trained adults improved elbow-flexor muscle size and strength similarly whether preacher-curl sets ended at approximately 1–3 RIR or at momentary muscular failure.
How HULL applies it: Treat failure as optional and use RIR to keep effort high without making maximum fatigue the default.
Foundational Research Registry
HYPERTROPHY · WEEKLY VOLUME · EFFECTIVE SETS
Weekly Training Volume and Muscle Growth
Higher weekly set volumes generally produce greater muscle growth than very low volumes, although the useful dose varies by training history, recovery, and muscle group.
How HULL applies it: Track weekly effective sets using full credit for direct primary work and half credit for meaningful secondary work. Targets are ranges—not universal prescriptions.
REP RANGES · LOAD · STRENGTH
Training Load, Strength, and Hypertrophy
Low- and high-load resistance training can both support hypertrophy when effort is sufficient, while heavier loads retain an advantage for maximal strength development.
How HULL applies it: Personalize rep guidance by goal and recommend load progression after the top of a productive range is achieved with the intended RIR.
RIR · HYPERTROPHY · FATIGUE MANAGEMENT
Proximity to Failure
Training close to failure can provide a strong stimulus without requiring every working set to reach momentary muscular failure.
How HULL applies it: Use RIR as effort context and preserve user choice rather than making failure a mandatory completion standard.
REST · PERFORMANCE · HYPERTROPHY
Rest Intervals and Hypertrophy
Rest duration influences performance and the quality of subsequent sets; there is no single interval that is ideal for every exercise and user.
How HULL applies it: Provide a practical, editable 90-second general default while allowing longer rest when performance or exercise demands warrant it.
PROGRAM DESIGN · SPLIT · FULL BODY
Full-Body Versus Split Routines
Full-body and split routines produce similar strength and hypertrophy outcomes when weekly training volume is equated.
How HULL applies it: Let schedule, preference, recovery, and session practicality guide the split rather than claiming one structure is inherently superior.
FREQUENCY · WEEKLY VOLUME · PROGRAM DESIGN
Training Frequency and Hypertrophy
Frequency helps distribute productive weekly work and manage session demands; frequency alone does not determine results.
How HULL applies it: Distribute target volume across available training days so workouts remain practical and recoverable.
What HULL Does Not Claim
- HULL does not diagnose, treat, or prevent injury or disease.
- Research averages do not guarantee an individual result.
- Set targets, rep ranges, RIR, and progression suggestions are adjustable guidance—not medical directives.
- Exercise technique, pain, health conditions, and clinical decisions require appropriate professional judgment.
Change Control and Corrections
Version 1.1 restores the original six-source registry, adds two 2026 RIR-versus-failure studies, and updates the weekly-volume explanation to match HULL’s existing effective-set model. It does not introduce a new training algorithm.
Evidence summaries may change as stronger research becomes available. Questions or correction requests can be sent to admin@joinhull.com.