Evidence guide · reviewed July 2026
Research should sharpen a decision, not decorate it. These are the claims Today uses, their confidence, and the line the product refuses to cross.
More weekly resistance-training volume generally produces more hypertrophy, but returns diminish and the best dose varies by muscle and lifter.
Full-body and split routines produce similar strength and hypertrophy when weekly volume is equated. Frequency mainly helps distribute useful work and fatigue.
Muscle growth can occur with low, moderate, and high loads when sets are sufficiently effortful. Moderate rep ranges are often the most practical, not uniquely anabolic.
Training to momentary failure is not consistently superior for hypertrophy when effort and volume are comparable. It usually creates more acute fatigue.
Longer rests often help maintain repetitions and load across sets. Roughly two to four minutes on compounds and 90 seconds to three minutes on isolations are practical defaults.
Sleep loss can impair muscle strength, but consumer sleep estimates cannot determine whether a specific workout will be productive.
Priority goes to systematic reviews, meta-analyses, position stands, and controlled trials. Group averages guide defaults; your longitudinal data guides personalization. Today does not diagnose injury, recovery, or medical conditions.