Evidence
How Long Does It Take to Lose Muscle? Returning After a Training Break
How long does it take to lose muscle after a training break, and what does that mean for your first session back?
Training for muscle and strength
Evidence-grounded writing on how to train, and on the calls Sterka's engine makes: the research, the methods, and the arithmetic behind them.
Training
The Upper/Lower Split: What It Decides, and What It Leaves to You
An upper lower split decides your week's shape: which muscles train on which day, how much rest each area gets, and which lift you meet fresh. It decides no numbers at all, and that gap is the difference between a split and a program.
The Engine
How Long Does a Muscle Take to Recover? What Sterka Assumes, and Why
Muscle recovery time is not one number. Sterka tracks it per muscle, each on its own half-life, because a single whole-body readiness score cannot tell a cooked chest from fresh legs.
The Engine
If You Run 5/3/1: Which Parts Sterka Keeps, and What a Spreadsheet Cannot Do
The 5/3/1 program mapped part by part onto Sterka's engine: the 90% training max, the four-week wave, the AMRAP set that sets your next training max — or the fixed single that replaces it where near-max work is held back — the ×0.9 reset, and the four reads a spreadsheet has no way to make.
The Engine
How Long to Rest Between Sets: 1:15 to 4:00, and What Picks the Number
How long you rest between sets is set by your goal, by whether the lift is a compound or an isolation, and by the load actually on the bar.
The Engine
A Deload Week Is the Plan Working, Not a Week Off
A deload week cuts your working sets to roughly half. On the wave's scheduled week the load comes down with them; on a plateau, cadence or on-demand deload, the weight stays exactly where it was.
The Engine
Why Your Workout App Never Adjusts
Rate a month of sessions as easy, flag a muscle as still fried, and next week arrives unchanged. That is not a bug. Here is what an engine that reads your logged sets has to do instead.
Training
How Much Does a Personal Trainer Cost, and What Are You Actually Paying For?
One-to-one strength coaching runs roughly €150 to €200 a month. Here is what that money buys, broken into the four duties a good coach performs, and which of them software can honestly take over.
The Engine
Why Week 3 Is One Heavy Single, Not a 1RM Test
On the Get Stronger goal, the peak of an intensity block's four-week wave is a 1+ AMRAP at 95% of a deliberately conservative Training Max — or a fixed heavy single where near-max work is held back. A calibration rep, not a one-rep-max test.
The Engine
Why Your Training Max Is 90% on Purpose
The strength Training Max is seeded at 90% of an already-conservative estimated 1RM — a deliberate double discount, so the week-3 peak lands in a productive zone instead of a number you cannot move: a 1+ AMRAP at 95% of that Max, or a fixed heavy single where near-max work is held back.
Evidence
How Many Sets, How Close to Failure, How Often: What the 2026 Strength Guidance Says
The 2026 ACSM position stand is the newest consensus on how to train for muscle and strength. Here are the four numbers it lands on (weekly sets, load, reps in reserve, frequency) and what Sterka does with each.