Every movement, explained.

Standing with the elbow pinned to the ribs, you rotate the forearm outward against a band. It looks like almost nothing is happening — a few inches of movement — and that is the point. This is not a muscle-building exercise; it is a retraining exercise for the small muscles at the back of the shoulder blade whose job is to hold the ball of the arm bone centred in its socket while bigger muscles move the arm. Momentum's system reads rotator cuff problems as a loss of exactly that: weak external-rotation control during elevation. The band is held at the side rather than overhead so the shoulder rebuilds the skill below the height that hurts.

Shoulders · Strength · Beginner

• Resistance band

On hands and knees, you extend one arm and the opposite leg until both are level with your back, then swap. Where the dead bug asks the spine to resist bending, this asks it to resist twisting — the multifidus, the small muscle spanning segment to segment along the spine, does anti-rotation work in Momentum's muscle map, and it appears on the system's inhibited list for the core. It sits in the same activate-glutes-and-core step of the low back flow, and adds a first, low-load rep of hip extension without the low back paying for it.

Core · Stability · Beginner

You rise onto the balls of your feet and lower back down. Plain, and the base of everything the calf and Achilles do: Momentum's system names inadequate calf load tolerance as the movement failure behind Achilles pain, and load tolerance has to be built somewhere before running asks the tendon for several times body weight on every stride. Bending the knee shifts the work from the gastrocnemius, which crosses the knee, onto the soleus beneath it — which is why both versions exist and why the straight-knee version alone is an incomplete answer.

Lower leg · Strength · Beginner

You draw the chin straight back — not down — as if making a double chin, and hold. It is the smallest exercise in this library and one of the most specific: it switches on the deep neck flexors, the small muscles lying against the front of the cervical spine that hold the head stacked over the shoulders. Momentum's system names their endurance failure as the movement failure behind tension headaches, and lists the deep neck flexors as inhibited on its upper-body chart. When they stop working the superficial neck muscles take over, which is the overuse pattern the system blames for the headache in the first place.

Neck · Stability · Beginner

Lying on your side with your knees bent and stacked, you open the top knee like a clam while your feet stay together. It is a small, isolated way to make the gluteus medius — the muscle on the side of the hip that keeps the pelvis level when you stand on one leg — work without the leg's full weight to lift. Momentum's system lists glute med as commonly weak, names weak glutes as a cause of knee pain, and blames knee collapsing inward on poor hip control. This is the first rung of the activate-glutes step in the running flow.

Hips · Strength · Beginner

• Resistance band (optional)

On your back, arms and knees up, you lower one arm and the opposite leg away from you while the low back stays flat on the floor. Momentum's system describes core instability as the inability to brace before the limbs move, and this drill is that sentence turned into an exercise: the limbs are the load, and the only measure of success is whether the spine stayed still while they moved. It belongs to the activate-glutes-and-core step shared by the low back and sciatica flows.

Core · Stability · Beginner

You breathe so that the ribs widen and the belly rises, instead of the chest and shoulders lifting. Momentum's system treats this as a movement, not a relaxation technique: it names diaphragmatic breathing failure as the movement failure behind stress and tension, rib expansion and diaphragm excursion as the failure behind breathing dysfunction, and pressure control as the failure behind core instability. The same muscle sits behind all three — the diaphragm both drives the breath and regulates the pressure inside the abdomen that stabilises the spine. When it stops moving well, the neck muscles take over the breathing, which is where the tension shows up.

Chest · Skill · Beginner

Standing with your heels off the edge of a step, you rise on both legs, shift onto one, and lower that heel slowly below the level of the step. Only the lowering is done on one leg — the tendon is being asked to control a lengthening load, which is the specific demand Momentum's system says it fails: progressive tendon loading failure, with inadequate calf load tolerance underneath it. Dropping below the step is what separates this from a calf raise; the tendon is loaded through the range where it is longest.

Lower leg · Strength · Intermediate

• Step

Forearm supported and palm facing down, you lift the weight with the other hand and lower it slowly with the working one — only the lowering is loaded. It is aimed at the tendon on the outside of the elbow where the wrist extensors share an attachment, the site people mean by tennis elbow. Momentum's system names repetitive gripping and forearm overuse as the cause of elbow pain and puts the forearms on the commonly-tight list. Worth reading alongside that system's own emphasis, though: the movement failure it names for elbow pain is force transfer failure from the trunk and shoulder — meaning the elbow is often where a problem lands rather than where it starts, and local loading is only part of an answer.

Forearm · Strength · Beginner

• Light dumbbell

Lying on your back with your knees bent, you press through your heels and lift your hips. It is the plainest way to make the gluteus maximus extend the hip while the low back is not required to hold you upright — which is why it appears in the activation step of three of Momentum's four flows. The system puts glute max on the commonly-weak list, names weak glutes as a cause of knee pain, and names loss of hip extension during gait as the movement failure behind hip pain. This is where hip extension gets rebuilt before it is asked to work standing up.

Glutes · Strength · Beginner

You push your hips backward and let your chest fold forward, keeping the spine long — the movement you should make every time you pick something up. Momentum's system is unusually pointed about this one: low back pain's movement failure is hip hinge plus core bracing failure, and its description of the problem is excessive lumbar motion instead of hip motion. This drill is the re-teach step of the low back flow, the fourth of five, deliberately placed after the hip flexors and QL have been released and the glutes and core have been woken up — because a hinge taught onto a stiff, unbraced body just rehearses the old pattern.

Hips · Skill · Beginner

• Dowel or broomstick (optional)

A nerve has to slide through the tissue around it as you move. When it cannot, movement pulls on it instead — which is what Momentum's system means by excessive neural tension during movement in sciatica, and by joint positioning and neural mobility in nerve entrapment. A glide restores that slide by tensioning the nerve at one end while releasing it at the other, so it moves back and forth rather than being stretched: for the sciatic nerve, straightening the knee while nodding the chin down, then reversing; for the median nerve at the wrist, extending the wrist while bending the elbow, then reversing. This is the teach-nerve-safe-movement step of the sciatica flow — it comes after the piriformis and hamstrings have been released, and it is the one drill in this library where more is emphatically not better.

Lumbar spine · Mobility · Beginner

Kneeling with your ankles anchored, you lower your torso toward the floor as slowly as you can, resisting the whole way with your hamstrings. It is the hardest exercise in this library and the most specific: Momentum's lower-body chart does not list the hamstrings as simply weak — it lists them as weak eccentrically, meaning weak at lengthening under load, which is what they are doing every time your foot swings forward before it lands. The system names eccentric load control failure as the movement failure behind muscle strains and force absorption and deceleration failure behind sports injuries. This trains the lowering, which is why the way down is the entire exercise.

Thigh · Strength · Advanced

• Partner or anchored ankle support
• Padding under the knees

Face down, arms angled overhead in a Y, you lift the arms a few inches off the floor. The target is the lower trapezius — the long lower third of the trapezius that runs from the mid-back up to the shoulder blade and helps turn it upward as the arm rises. Momentum's upper-body chart lists the lower traps as commonly weak and the upper traps as commonly tight, which is the whole reason for the Y shape and the strict no-shrug rule: this is the activation step of the shoulder flow, and it only works if the muscle that is already overworking stays out of it.

Shoulders · Strength · Beginner

• Light dumbbells (optional)

Lying on your back with the arm pointed at the ceiling, you push the fist a few inches higher — the elbow stays locked, so the only thing that can move is the shoulder blade sliding forward around the ribs. That slide is the serratus anterior, the fan of muscle along the side of the ribcage that both holds the shoulder blade against the chest wall and helps rotate it upward as you reach. Momentum's upper-body chart lists it as commonly weak, and its shoulder flow names it explicitly in the activation step.

Shoulders · Strength · Beginner

• Resistance band (optional)

The same job as band external rotation, done lying on your side so gravity supplies the resistance and the floor supplies the stability. Because your torso cannot cheat — you are lying on it — this is the version that isolates the back of the cuff most cleanly, which makes it useful when someone shrugs or leans every time they try the standing version. Momentum's upper-body chart puts the rotator cuff on the commonly-weak list; this is one of the two ways this system asks it to work.

Shoulders · Strength · Beginner

• Light dumbbell (optional)

The same muscle as the clamshell, with a longer lever: lying on your side, you lift the whole straight top leg. Because the weight is now out at the ankle rather than the knee, the gluteus medius has considerably more to hold — which is what makes it the next step up once the clamshell is clean. The cue that matters is the small backward drift of the leg: swinging it forward hands the work to the TFL at the front of the hip, which Momentum's chart already lists as commonly tight.

Hips · Strength · Beginner

Stand on one leg and stay still. It is the first step of Momentum's running flow — assess single-leg stability — and it doubles as the exercise, because running is a series of single-leg stances and most people who hurt while running cannot hold one quietly. The system names proprioception and stabiliser activation as the failure behind balance problems: what you are training is the constant, small conversation between the foot gripping the floor and the hip holding the pelvis level.

Hips · Stability · Beginner

A staggered stance — one foot forward, one back — and you lower straight down until the back knee approaches the floor. It is the bridge between two-legged strength and single-leg control: the back leg is still there for balance, but the front leg does most of the work, so the hip and knee have to cooperate under real load. Momentum's system names hip-dominant control during squat and step as the movement failure behind knee pain, and this is the first place that control is loaded rather than merely practised.

Hips · Strength · Intermediate

• Dumbbells (optional)

Standing on one leg on a step, you lower the other heel slowly toward the floor and come back up. Everything the split squat allowed you to hide is now exposed: one leg, controlled on the way down, with the pelvis and knee entirely dependent on the hip. Momentum's system names knee collapsing inward as the movement failure behind knee pain and poor single-leg stability as the failure behind running problems — this is the drill where both are visible and trainable in the same repetition, which is why it also serves as an assessment.

Hips · Stability · Intermediate

• Step or box

A towel on the floor, and you drag it toward you using only your toes. The target is the small muscles inside the foot itself — Momentum's lower-body chart lists the intrinsic foot muscles as inhibited, meaning present but not switching on, and names weak arch control during gait as the movement failure behind plantar fasciitis. These muscles are the arch's active support. When they do not work, the plantar fascia becomes the only thing holding the arch up, which is roughly the definition of the problem. This is the foot half of the running flow's activate step.

Foot · Strength · Beginner

• Towel

Forearms on a wall, you slide them upward overhead and back down. This is the fourth step of Momentum's shoulder flow — reintroduce overhead motion — and it is deliberately the easiest possible version of the movement that hurts: the wall carries the arm's weight and gives constant feedback, so the shoulder blade can practise turning upward under the arm rather than the arm hauling itself up off a stuck blade. That upward rotation is the failure the system blames for shoulder pain, so this drill comes after the pecs and upper traps have been released and the lower traps and serratus have been woken up — never before.

Shoulders · Mobility · Beginner

• Wall