Advice you can check.

Sets, reps, load, effort and rest — the decisions your plan makes for you.

• Strong evidenceMore hard sets per muscle per week produce more growth, across the range most people train in.
• Strong evidenceOnce weekly volume is matched, splitting it across more sessions doesn't add growth.
• Strong evidenceLight and heavy loads build similar amounts of muscle when sets are taken close to failure.
• Strong evidenceStrength, unlike size, does depend on training with heavy loads.
• Moderate evidenceStrength and size respond to different things: strength to intensity, size to volume.
• Moderate evidenceTraining to absolute failure isn't necessary, and for strength it may be counterproductive.
• Moderate evidenceRating a set by how many reps you had left is a usable way to gauge effort, and gets more accurate as you get more experienced.
• Moderate evidenceA single hard set per exercise, once to three times a week, is enough to increase strength in trained men.
• Moderate evidenceLonger rests between sets support greater strength gains, particularly in trained lifters.
• Moderate evidenceTraining through a full range of motion generally beats cutting it short.
• Moderate evidenceStructured variation in training over time gives a small strength advantage over keeping everything constant.
• Moderate evidenceDoing cardio alongside lifting doesn't compromise muscle size or maximal strength.
• Strong evidenceOlder adults gain muscle and strength from resistance training, and should train with meaningful load rather than token weights.
• Moderate evidenceCurrent evidence shows no consistent effect of menstrual cycle phase on strength performance or on gains from resistance training.
• Strong evidenceThe WHO recommends 150–300 minutes of moderate aerobic activity a week, plus muscle-strengthening work on two or more days.
• Moderate evidenceMuscle-strengthening activity is associated with lower all-cause mortality and lower risk of major chronic disease.
• Moderate evidenceDoing several sets per exercise produces greater strength gains than doing one.
• Moderate evidenceWarming up improves performance in the large majority of studies that measured it.
• Moderate evidenceRep speeds anywhere from about half a second to eight seconds per rep produce similar muscle growth.
• Moderate evidenceMachines and free weights build muscle equally well.
• Moderate evidenceResistance training improves bone mineral density in postmenopausal women.
• Moderate evidenceStrength is lost much more slowly than people fear when training stops.

Sleep, soreness, easy weeks, and a few popular things that do less than advertised.

• Strong evidenceAcute sleep loss measurably impairs physical performance.
• Moderate evidenceExtending sleep improves athletic performance in people who were under-slept.
• Moderate evidenceMuscle soreness is not a valid indicator of how well a session worked.
• Moderate evidenceRegular cold water immersion after lifting reduces the long-term muscle gains from that training.
• Moderate evidenceFoam rolling has small effects on performance and recovery — real, but modest.
• Strong evidenceLong static stretches immediately before training reduce strength and power output.
• Moderate evidenceTrue overtraining syndrome is uncommon and takes weeks to months of recovery; short-term overreaching is far more usual.
• Limited evidencePlanned easy weeks are near-universal practice in strength sport but thinly evidenced.
• Strong evidencePhysical activity meaningfully reduces symptoms of depression, anxiety and psychological distress.

General principles only. Nothing here is personalised dietary advice.

• Strong evidenceProtein intakes beyond roughly 1.6 g per kg of bodyweight per day don't add further to training-induced gains in lean mass.
• Moderate evidenceSpreading protein across the day in reasonably sized meals is a sensible default for muscle building.
• Moderate evidenceThe narrow post-workout 'anabolic window' is far less important than total daily intake.
• Moderate evidenceLosing weight slowly, with adequate protein and continued resistance training, preserves lean mass and performance better than losing it fast.
• Strong evidencePersistently eating too little for the training you do harms bone, hormonal and metabolic health, not just performance.
• Strong evidenceCreatine monohydrate is effective for increasing muscle mass and strength alongside training, and is safe in healthy people at recommended doses.
• Strong evidenceCaffeine improves several aspects of exercise performance.
• Strong evidenceCarbohydrate availability is a determinant of performance in prolonged and high-intensity training.
• Strong evidenceOnly a small number of supplements have credible performance evidence behind them.

How to load a body that's complaining — never how to work out what's wrong with it. See a clinician for that.

• Strong evidenceStrength training substantially reduces the rate of both acute and overuse injuries, and the effect increases with the dose.
• Strong evidenceExercise reduces pain and improves function in chronic low back pain.
• Strong evidenceDisc degeneration, bulges and similar imaging findings are common in people who have no pain at all, and become more common with age.
• Moderate evidenceIn chronic musculoskeletal pain, exercise that provokes some pain offers a small short-term benefit over strictly pain-free exercise.
• Moderate evidenceContinuing to train while keeping pain within an agreed limit produced outcomes as good as resting from activity, in Achilles tendinopathy.
• Strong evidenceExercise reduces pain and improves physical function in knee osteoarthritis.
• Moderate evidenceThe popular acute-to-chronic workload ratio has serious conceptual and statistical problems, and shouldn't be treated as a rule for safe progression.