Understand your body. Shape your progress.

The Body pillar answers one simple question: where is a structure and what does it do? The pillar describes the major muscles and their attachments, the joints, the tissues all of that is made of, and the systems that make them work.

The Movement pillar answers one question: how does the body produce this movement? Six families of movement — squat, hip hinge, pushes and pulls — provide a reading grid for almost every exercise, joined by walking and running.

The Adaptation pillar answers one question: how does the body change when it is trained? Three mechanisms and two videos describe muscle growth, the role of mechanical tension and the synthesis of proteins.

The Energy pillar answers one question: where does the energy for a muscle contraction come from? Two mechanisms and two videos describe ATP, phosphocreatine and the glycogen stored in muscle.

The Recovery pillar answers one question: how does the body return to its resting balance after an effort? The launch corpus covers sleep, in one written page and one video.

What actually makes a muscle grow? This page follows the chain of events that links a set of exercise to a thicker muscle fibre, and separates what is established from what is still debated by research.

Should you lift heavy, train to exhaustion, or simply do a lot? This page untangles three variables that are often confused, shows how they combine over the course of a set, and states the level of evidence behind each one.

A muscle does not contract as one block. It contracts in units, recruited in an order that is not left to chance — and that recruitment improves before the muscle gets any bigger.

Six steps to break a movement down: the pattern it follows, the joints it moves, the muscles that produce and those that restrain, and what body proportions change about it.

A six-step reading pathway that follows muscle energy from the second to the night: the instant recharge of ATP, the glycogen stores and their water, then the role of sleep. A closing quiz lets you check what you have taken in.

Nine steps following a single movement, from the decision through to recovery, crossing the systems of the body. The longest pathway in this corpus, and the only one where no step has a 3D scene.

A six-step entry route for anyone unsure where to start. It begins with the whole body, works down to a muscle, then to the joint it crosses, and back up to the movement.

The most mobile joint in the body is also the one that holds least by its shape. Six steps to understand what follows from that, from the glenoid cavity to reaching overhead.

A six-step reading pathway that connects the mechanical signal produced during a set, the protein building that follows, and the volume of work accumulated over a week. A quiz at the end lets you check what you have taken in.

Eight steps following protein, carbohydrate, fat and water from the meal to the muscle. A pathway of mechanisms, with no amounts, no recommended foods and no timing.

The talus is wedged between two malleoli like a tenon in a mortise. The ligaments holding it are not symmetrical, and that asymmetry explains a great deal.

Two mechanisms inside one capsule: a hinge that bends the arm, and a pivot that turns the palm over. The radius rotates in place, held by a ring.

A sphere set deep in a socket, locked by three ligaments that tighten in extension. That is what makes standing possible without continuous muscular effort.

Two poorly matched surfaces, an almost flat plateau under rounded condyles. Menisci, cruciate and collateral ligaments make up for that lack of fit.

Five vertebrae, five discs and a set of ligaments. Each level moves only a few degrees: it is their sum that gives the trunk its range.

The most mobile joint in the body, and the one that holds least by its shape. A wide head resting on a shallow socket, retained by soft tissue.