Training, as the research sees it.
Short answers on strength training, nutrition and recovery. Each with an evidence grade and the studies behind it, versioned like code.
Training volume
More hard sets per muscle per week lead to more growth, but each extra set adds a bit less than the one before.
Training frequency
For muscle growth it doesn't matter much how many days you spread your sets over. For strength, practising the lift more often helps.
Proximity to failure (RIR)
For muscle growth it pays to train close to failure. For strength it matters much less.
Load & rep range
Muscles grow similarly with light and heavy loads as long as sets are hard. Maximal strength needs heavy loads.
Range of motion & stretched position
Full range of motion is a good default. Training in the stretched position seems especially important for growth.
Rest between sets
Resting more than 60 seconds gives a small edge for hypertrophy. Beyond about 90 seconds there's little measurable difference.
Repetition tempo
Whether a rep takes 1 or 6 seconds hardly matters for muscle growth. Only extremely slow reps do worse.
Free weights vs. machines
For muscle growth it doesn't matter. For strength: you mostly get strong at what you train.
Blood flow restriction (BFR)
Light weights with restricted blood flow build about as much muscle as heavy training. For maximal strength, heavy is still better.
Periodization
Planned changes in volume and intensity give a bit more maximal strength, but not more muscle.
Daily protein
Around 1.6 g of protein per kg body weight is enough for most people. Up to about 2.2 g/kg may still add a little.
Protein per meal
The old rule that “anything over 20–30 g per meal is wasted” doesn't hold up.
Building muscle in a calorie deficit
A deficit slows muscle gain but barely affects strength gains. At around 500 kcal per day, average lean mass gain drops to zero.
Intermittent fasting & muscle
An eating window like 16:8 doesn't cost muscle or strength on average, as long as you lift.
Creatine
One of the most researched supplements: effective for performance and safe for healthy people. Its direct effect on muscle growth is small, though.
Caffeine
3–6 mg per kg body weight reliably improves performance. More just adds side effects.
Beta-alanine
Helps with hard efforts of roughly 1–4 minutes. For classic lifting with short sets it does little.
Combining cardio & strength training
Cardio doesn't kill gains. Hypertrophy and maximal strength aren't impaired on average, only explosive strength a little.
Sleep
One bad night costs only a little strength. Several short nights in a row show up in heavy compound lifts.
Stretching before training
Short static stretches (under 60 seconds per muscle) barely hurt. Long holds right before training cost strength.
Ice baths after training
Regular ice baths right after lifting probably blunt muscle growth.
Training breaks & muscle loss
One to four weeks off barely costs maximal strength. Longer breaks slowly cost muscle.
Strength training for women
Relative to their starting point, women gain as much muscle and strength as men. For upper-body strength, even slightly more.
Strength training as you age
Even a little training has clear effects in older adults. More strength needs a bit more volume.
Goals & if-then plans
“If X happens, then I'll do Y” demonstrably helps you follow through. The effect is smaller than early numbers suggested, though.
Building habits
The “21 days” is a myth. In the best-known study it took 66 days on average, with a huge range. Missing one day doesn't break it.
Self-talk
Deliberate self-talk moderately improves sports performance, especially when practised beforehand.
Mental training & visualisation
Vividly imagining movements does make you somewhat stronger. It doesn't replace real training, though.
Is willpower a battery?
The idea that self-control drains like a battery (“ego depletion”) failed a large replication test.
Growth mindset
“Abilities can be developed” is a sensible attitude. But brief mindset interventions show only very small effects in meta-analyses.
Stoicism: what's in your control?
Epictetus's core idea: separate what you can influence from what you can't, and put your energy only into the former.
Aristotle: you become what you repeatedly do
For Aristotle, character comes not from knowledge but from practice. You become brave by acting bravely.
Marcus Aurelius: the obstacle becomes the way
The Stoic emperor noted, in essence: what stands in the way of action can itself become a means of action.