To test if rest time matters, researchers made sure both groups did the exact same amount of total lifting—so any differences (or lack of them) must be due to rest time, not how much they lifted.
Scientific Claim
Volume-load equating in resistance training studies is a viable method to isolate the effects of inter-set rest intervals on muscle and strength adaptations, reducing confounding from differences in total work performed.
Original Statement
“The present study compared the effects of volume-load-equated resistance-training programs with very-short (SHORT) and long (LONG) inter-set rest intervals on changes in muscle size and maximum strength.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The authors correctly describe volume-load equating as a methodological control. No causal claim is made about volume equating itself, only its use as a tool, making the statement appropriately stated.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Systematic Review & Meta-AnalysisLevel 1aWhether volume equating consistently produces null effects for rest intervals across studies, validating its use as a control method.
Whether volume equating consistently produces null effects for rest intervals across studies, validating its use as a control method.
What This Would Prove
Whether volume equating consistently produces null effects for rest intervals across studies, validating its use as a control method.
Ideal Study Design
A meta-analysis of all RCTs comparing rest intervals in resistance training, stratifying by whether volume was equated or not, to determine if volume control consistently eliminates differences in hypertrophy or strength outcomes.
Limitation: Cannot determine if volume equating is sufficient to control for all confounders like fatigue or hormonal response.
Randomized Controlled TrialLevel 1bThat volume equating successfully isolates rest interval effects compared to non-equated conditions.
That volume equating successfully isolates rest interval effects compared to non-equated conditions.
What This Would Prove
That volume equating successfully isolates rest interval effects compared to non-equated conditions.
Ideal Study Design
A 3-arm RCT comparing 20s vs 2min rest intervals under volume-equated vs non-equated conditions (n=80), measuring hypertrophy and strength to determine if equating eliminates differences seen in non-equated studies.
Limitation: Cannot fully replicate real-world training where volume naturally varies with rest.
Prospective Cohort StudyLevel 2bHow often volume equating is applied in real-world training and its impact on outcomes.
How often volume equating is applied in real-world training and its impact on outcomes.
What This Would Prove
How often volume equating is applied in real-world training and its impact on outcomes.
Ideal Study Design
A 1-year cohort tracking 150+ trainers who either self-equate volume or not during rest interval manipulation, measuring hypertrophy and strength changes to assess real-world validity.
Limitation: Cannot control for self-selection or adherence differences.
Cross-Sectional StudyLevel 3Association between volume-equating practices and perceived training effectiveness.
Association between volume-equating practices and perceived training effectiveness.
What This Would Prove
Association between volume-equating practices and perceived training effectiveness.
Ideal Study Design
A cross-sectional survey of 300+ trainers and coaches, asking whether they equate volume when manipulating rest intervals and whether they believe it affects outcomes.
Limitation: Cannot establish causal or physiological relationships.
In Vitro Cell StudyLevel 5Whether mechanical load (volume) alone drives hypertrophy signals independent of rest-induced metabolic stress.
Whether mechanical load (volume) alone drives hypertrophy signals independent of rest-induced metabolic stress.
What This Would Prove
Whether mechanical load (volume) alone drives hypertrophy signals independent of rest-induced metabolic stress.
Ideal Study Design
An in vitro study exposing human myotubes to identical mechanical stretch protocols with or without metabolic stress (lactate, pH drop), measuring mTOR activation and protein synthesis to isolate volume vs rest effects.
Limitation: Cannot replicate systemic physiological responses of whole-body training.
Evidence from Studies
Supporting (1)
When people lifted weights with either short or long breaks between sets—but did the same total amount of work—both groups got just as strong and built the same amount of muscle. This means comparing rest times only works if you keep the total work the same.