1.0 How to Read This Series: Key Terms and Unit Cheat Sheets

The short version

This series reads like a textbook: five units, numbered articles, each one leaning on the ones before it. That structure is deliberate — 2.5 assumes you have read 2.1, and most of Unit 3 leans on both. But nobody opens a textbook at page one and reads straight through, and you should not have to.

This article is the reading aid. It does three jobs. It shows how the units fit together. It defines the terms that later articles use without stopping to explain. And it collects the questions readers actually arrive with — why am I not getting stronger, why can I not focus for ten minutes, why does everything hurt when I sit all day — and points each one at the article that answers it properly.

The answers here are the compressed version. They are enough to act on this week. The articles they point to carry the mechanisms and the evidence, and that is where the numbers in brackets take you.

How the five units fit together

Unit 1 (1.1–1.7) is the foundation: what the body is built from, how it fuels movement, how the nervous system runs it, and how it adapts between sessions. Start at 1.1 if nothing specific brought you here.

Unit 2 (2.1–2.5) covers strength and muscle: the principles of loading, maximal strength, strength relative to bodyweight, muscle growth, and power.

Unit 3 (3.1–3.18) turns gym qualities into sport qualities: plyometrics, sprinting, agility, combat and field sports, and the transfer problem — why strong athletes are not automatically fast ones.

Unit 4 (4.1–4.17) walks the body joint by joint and takes mobility seriously: what range of motion is, how to change it, and how to keep joints working under load for years.

Unit 5 (5.1–5.28) goes upstairs. It opens with sport psychology and ends deep in the brain: dopamine, stress chemistry, habits, sleep, and the circuits that decide whether you act at all.

The words the series uses without stopping

Every field has a working vocabulary it stops explaining after the first chapter. These are ours. Each definition is deliberately short; where a term deserves a full article, the link takes you there. Skim once now, come back when a sentence somewhere else refuses to parse.

Counting work in the gym

Rep and set. A rep is one complete movement. A set is a run of reps done without resting. “3×10” means three sets of ten reps, with rest between the sets. Nearly every prescription in Unit 2 is written this way.

Working sets and warm-up sets. Warm-up sets rehearse the movement with light loads and do not count toward the day’s work. Working sets are the hard ones the program is actually prescribing. When an article says “three sets,” it means working sets.

One-rep max (1RM). The heaviest load you can lift once with technique you would defend. Programs use it as a reference point — “80% of 1RM” is a weight you could lift about eight times when fresh. How maxes are built and tested is the business of 2.2.

Reps in reserve (RIR). How many reps you had left when you ended the set. Stopping one or two short of failure produces most of the stimulus at a fraction of the fatigue cost; 2.4 examines that trade-off in detail.

RPE. Rating of perceived exertion — a 1–10 score for how hard a set felt. In lifting it mirrors RIR from the other side: RPE 8 means two reps were left. It is subjective on purpose; it adjusts for the days the bar feels heavier than the maths says it should.

Tempo. The speed each phase of a rep is performed at, often written as four digits — “3010” is three seconds down, no pause, one second up, no pause. Slowing a phase is a way of making a light weight expensive.

Concentric, eccentric, isometric. The three things a working muscle can be doing: shortening as it produces force (lifting the weight), lengthening under tension (lowering it), or holding still against load. The eccentric phase is where most soreness comes from and where some of the most useful adaptations live — 3.7 is built on it.

Compound and isolation. A compound exercise moves several joints at once — squats, presses, rows. An isolation exercise moves one — curls, leg extensions. Programs are usually built on compounds and finished with isolations.

Progressive overload. The demand has to rise for the adaptation to continue: more load, more reps, more range, better positions. Not more of everything at once — more of something, tracked. The logic behind it is most of 2.1.

AMRAP. As many reps (or rounds) as possible — a set taken to the point where the next honest rep is not there. Used sparingly as a test, not a weekly habit.

DOMS. Delayed-onset muscle soreness — the stiffness that arrives a day or two after unfamiliar work, peaks around 48 hours, and fades as the tissue adapts. It tracks novelty, not progress (1.7).

Building a program

Volume. How much total work you do — usually counted as hard sets per muscle or movement per week. The dial most responsible for muscle growth, and the first suspect when recovery fails.

Intensity. In this series, how heavy the load is relative to your max — not how sweaty the session felt. 85% of 1RM is high intensity even when it is over in three seconds.

Frequency. How often a muscle or movement is trained per week. Mostly a tool for distributing volume into doses you can recover from.

Periodisation. Organising training into phases with different emphases — building a base, then strength, then power — rather than doing everything at once forever. 2.1 covers the shapes this takes.

Mesocycle. One training block, typically three to six weeks pointed at one quality, usually ending in an easy week. Programs are stacks of these.

Deload. A planned easy week — roughly half the usual work — every four to six weeks. You adapt between sessions, not during them (1.7); a deload is how that gap gets scheduled instead of skipped.

Taper. The deliberate reduction of training in the final days before a competition, so fatigue falls faster than fitness. The difference between arriving fresh and arriving trained-but-tired.

GPP and SPP. General physical preparation — broad fitness, everything a base layer — and specific physical preparation, the work that looks like your sport. The transfer from one to the other is the subject of 3.18.

Set schemes you will meet in the workout builder

Superset. Two exercises alternated with little or no rest between them, usually working opposing muscles. A time-saver more than a secret method.

Drop set. Take a set near failure, immediately reduce the load, continue. A way of extending a set past where the original weight ends it — useful for muscle, costly to recover from.

Giant set. Three or more exercises run back to back before resting. Dense, brutal on conditioning, best used deliberately rather than by accident.

Pyramid set. Working up in load and down in reps across sets (or the reverse). An old structure that survives because it doubles as its own warm-up.

Cluster set. One set broken into small groups of reps with short rests inside it — say three reps, fifteen seconds, three more. The pauses keep bar speed high, which is why power work borrows it (2.5).

The engine

ATP. Adenosine triphosphate — the molecule every muscle contraction actually spends. The body holds a few seconds’ worth; everything below exists to remake it faster than you burn it (1.4).

Phosphocreatine. The emergency fund: a phosphate stored in muscle that rebuilds ATP almost instantly and runs dry in about ten seconds. It is why a max sprint and a max lift feel possible — briefly — and why creatine supplementation targets this system.

Glycolysis. Breaking down carbohydrate for quick energy without waiting for oxygen. It funds hard efforts from about ten seconds to a couple of minutes, and its by-products are the burn you feel arriving.

Aerobic and anaerobic. Two ways of paying for work. Aerobic metabolism uses oxygen and funds long, steady effort and the recovery between bursts. Anaerobic pathways fund short, hard efforts and send the bill later. Which system your sport draws on, and when, is mapped in 1.4.

Lactate and lactate threshold. Lactate is a by-product of fast carbohydrate burning that the body recycles as fuel — it is a marker of hard work, not a poison. The threshold is the effort level where it accumulates faster than it clears; hold anything above it and the clock starts running.

VO2 max. The most oxygen your body can use per minute — the size of the aerobic engine. Trainable, but slowly, and less decisive on its own than the number’s reputation suggests (1.4).

Training zones. Effort bands, usually numbered 1–5 from easy to maximal, anchored to heart rate or pace. Zone 2 — comfortable, conversational, sustainable for an hour or more — is where most aerobic base gets built.

HIIT. High-intensity interval training: repeated hard bursts separated by recovery periods. Time-efficient conditioning — and not a synonym for “any workout that hurts.”

Speed, spring and agility

Rate of force development. How fast force rises once you start pushing. Sport rarely grants the half-second a max lift takes; RFD is the quality that decides what you can produce in the tenth of a second you actually get (2.5).

Ground reaction force. The push the ground gives back when you push into it. Every jump, stride and cut is an exercise in producing and redirecting it.

Triple extension. Ankle, knee and hip straightening together — the finishing position of a jump, a sprint stride and an Olympic lift. When coaches say “finish tall,” this is what they mean.

Acceleration and max velocity. Two different skills inside sprinting: building speed from a standstill (low body angle, long pushing steps — 3.6) and holding top speed once upright (stiff, springy, fast off the ground — 3.4). Most field-sport sprinting is the first one.

Stride length and stride frequency. The two numbers speed multiplies: how far each step carries you and how many you take per second. Chasing frequency by shortening the stride, or length by overreaching, makes runners slower; both improve as force and stiffness do.

Stretch-shortening cycle. The spring in action: a rapid stretch immediately before a contraction makes the contraction stronger. It is why you dip before you jump, and it gets a full article at 3.2.

Countermovement jump. A jump preceded by a quick dip — the standard test of lower-body power, because the dip recruits the stretch-shortening cycle the way sport does.

Depth jump. Step off a box, land, and jump again the instant you touch down. The highest-intensity plyometric there is, and earned rather than started with (3.1, 3.3).

Reactive strength index. Jump height divided by ground contact time — a number for how well you use the ground briefly. The quality it measures is the subject of 3.9.

Agility and change of direction. Change of direction is the closed skill — a planned cut around a cone. Agility adds the part that decides games: reading a moving opponent and choosing the cut in real time (3.10, 3.13).

The hardware

Central nervous system (CNS). Brain and spinal cord — the command layer that decides which muscles fire, how many fibres join in, and in what order. Much of early strength gain is this system learning, before the muscle changes size (1.5).

Motor unit. One motor neuron and every muscle fibre it commands. Force is graded by recruiting more units and firing them faster; heavy and explosive work is largely training this recruitment (1.5).

Type I and type II fibres. Slow-twitch fibres are fatigue-resistant and modest in force; fast-twitch fibres are powerful and quick to tire. Everyone carries both in proportions that vary; training determines how much of what you have gets used (1.2).

Tendon and ligament. Tendons connect muscle to bone and transmit force; ligaments connect bone to bone and keep joints honest. Tendons adapt to load like muscle does, only slower — which is why they are usually the limiting tissue when training ramps up quickly.

Fascia. The connective-tissue sheet that wraps and links muscles into continuous lines. It is why tension in one place can be felt somewhere else, and it gets its own article at 1.6.

Agonist and antagonist. The muscle producing a movement and the one opposing it — biceps and triceps, quadriceps and hamstrings. Coordinated relaxing of the antagonist is part of what makes movement smooth and fast.

Kinetic chain. The linked segments — foot, knee, hip, trunk, shoulder, hand — that force travels through. A weak or wobbly link leaks force and collects injuries; 1.3 and 4.7 deal in these terms constantly.

Proprioception. The body’s sense of where it is without looking — fed by receptors in muscles and joints. It is what balance training actually trains.

Mobility, in its own words

Mobility and flexibility. Flexibility is how far a joint can be taken. Mobility is how far you can take it yourself, with control. Sport mostly cares about the second one — 4.1 explains why the difference matters.

Range of motion (ROM). The arc a joint can move through, measured or felt. “Full ROM” in an exercise means using all of it you can control (4.9).

End range. The last few degrees before a joint runs out of motion — the region where control is weakest, injuries concentrate, and targeted strength work pays best (4.14).

Dynamic and static stretching. Moving through range with control — leg swings, lunges — versus holding a position for time. Dynamic work belongs before training (4.10); long static holds sit better after it (4.11).

CARs. Controlled articular rotations — slow, deliberate circles through a joint’s full available range, used to maintain and map it. The method has its own article at 4.16.

PNF, PAILs and RAILs. Stretching methods that add muscle contractions inside the stretch — contracting the stretched tissue, then the opposite side, to convince the nervous system the new range is safe to use. Unpacked in 4.17.

Loaded mobility. Strength training done at long muscle lengths and deep positions, so new range arrives with the strength to own it (4.13).

The chemistry upstairs

Neurotransmitter. A chemical messenger released by one neuron to change what the next one does. Dopamine, serotonin, noradrenaline and acetylcholine are the four this series returns to; 5.6 is the map.

Dopamine. Less a pleasure chemical than a pursuit chemical: it rises in anticipation of reward and drives the work of getting it. A stream of cheap, effortless rewards teaches the system to expect reward without effort — 5.7 covers how it works and 5.8 what happens when it is overrun.

Serotonin. A mood- and impulse-steadying neuromodulator, sensitive to sleep, light and exercise. Its athletic relevance — including its role in the fatigue of long efforts — is covered in 5.9.

Noradrenaline. The alertness chemical — it sharpens attention and readies the body for action. Too little and you are flat; too much and you are jittery. The arousal curve it drives is the spine of 5.3.

Acetylcholine. The messenger of focus and of movement itself — it carries the command from nerve to muscle at every contraction, and supports attention and learning upstairs (5.9).

Cortisol. The main stress hormone. In pulses it is useful — it mobilises fuel and sharpens attention. Held high for weeks by poor sleep and unbroken stress, it starts costing recovery, mood and adaptation (5.13).

Allostatic load. The running total of stress on the system — training, work, poor sleep, worry — which all draws on the same recovery budget. The reason a hard week at the office shows up in your squat (5.13).

Orexin. A hypothalamic peptide that holds the brain awake and ready to act; it responds to sleep, light and feeding. When it runs low, everything feels like wading. It appears alongside its neighbours in 5.12.

Adenosine. A by-product of being awake that accumulates through the day and produces sleep pressure. Caffeine works by blocking its receptors — it does not remove tiredness, it hides the signal, and the adenosine is still there when the caffeine leaves.

Melatonin. The darkness hormone: released in the evening as light falls, it tells the body night has started. Bright screens late in the evening delay it, and sleep with it (5.17).

Circadian rhythm. The roughly 24-hour clock that times sleep pressure, hormones and body temperature. Morning light, regular meals and a consistent bedtime keep it anchored; 5.17 covers what happens when it drifts.

Arousal. In performance psychology, the body’s activation level from drowsy to frantic — not excitement in the everyday sense. Every task has a level it goes best at; managing yours toward it is the skill taught in 5.3.

Interoception. The sense of the body’s internal state — effort, heartbeat, breath, the difference between nerves and readiness. Athletes with better interoception pace and regulate better; 5.27 explains the machinery.

Habit loop. Cue, action, reward — the three-part circuit the brain uses to automate behaviour. Build one deliberately and training stops costing willpower; leave one to build itself and you get doomscrolling (5.14).

Neuroplasticity. The brain’s capacity to rewire with repetition. It is the mechanism under every skill, every habit — and, less cheerfully, under a shortened attention span, which is also learned (5.16).

Nootropics. The catch-all label for supplements marketed as cognitive enhancers. The evidence runs from solid (caffeine) to thin; 5.20 sorts the shelf.

Biohacking. The umbrella term for do-it-yourself optimisation — cold exposure, light protocols, wearables, supplement stacks. Some of it is repackaged basics, some is promising, some is noise; 5.18 sorts which is which.

The brain’s departments

Prefrontal cortex. The front of the brain: plans, focus, impulse control, holding a goal in mind while the feed calls. It is the part trained by single-task work and drained by task-switching (5.25).

Basal ganglia. The deep structures that select actions and store habits. Once they own a behaviour, it runs without deliberation — which is the whole point of building habits on purpose (5.24, 5.14).

Cerebellum. The structure at the back that times and smooths movement, comparing what you intended with what happened and correcting the difference. Skill practice is largely its education (5.23).

Limbic system. The emotional circuitry — amygdala, hippocampus and neighbours — that tags experiences as threatening or safe and files the memories. Competition nerves start here, and so does their retraining (5.26).

Unit 1 cheat sheet: the body, fuel and recovery

Why am I always tired?

Before assuming anything exotic, audit the basics: hours actually asleep, food actually eaten, caffeine after noon, daylight seen. Most persistent tiredness in training people traces back to one of those four. If you train hard, a flat day or two after a heavy block is not a problem — it is the adaptation window doing its job (1.7). Tiredness that survives two full weeks of honest sleep is worth a conversation with a clinician.

Why am I sore, and is soreness progress?

Soreness mostly tracks novelty — new exercises, new ranges, big eccentric loads — not the quality of the session. It fades as the tissue adapts, even while the training keeps working. Easy movement, food and sleep clear it faster than lying still does. Chasing soreness as proof of a good workout leads to programs that are hard to recover from and no better at building anything (1.7).

Why has my progress stopped?

An adaptation continues only while the demand keeps rising. The usual suspects, in order: the training has quietly stopped getting harder; sleep is short; protein is low; there has been no easy week in months. Fix them in that order and give it six weeks before concluding anything (2.1, 1.7).

Do I need to train every day?

No — and past a point it works against you, because the improvements are built between sessions. Three to five focused sessions a week, with at least one genuinely easy day, outperforms seven forced ones over any timescale that matters (1.7).

Unit 2 cheat sheet: strength and muscle

Why has my strength stalled?

Strength plateaus have a short list of causes: the same weights every week, short sleep, low protein, no deloads, or a new program every month so nothing runs long enough to work. Pick one lift, add a small amount of load or one rep per week, hold everything else steady for eight to twelve weeks, and reread 2.2 at the halfway mark.

How many sets and reps?

As a starting frame: for strength, heavier loads for 3–6 reps, 3–5 sets; for muscle size, moderate loads for 6–12 reps, 3–4 sets; most sets ending 1–2 reps short of failure. Those ranges have soft edges — 2.4 explains why sets taken close to failure grow muscle across a much wider rep range than the textbook suggests.

How long before muscle is visible?

Strength moves first — much of the early gain is the nervous system learning the lift. Visible muscle usually needs two to three months of consistent training with enough food. Monthly photos beat the mirror, which renegotiates daily (2.4).

Will lifting make me slow?

The evidence runs the other way: stronger legs produce more force per step and more height per jump, which is why sprint and jump programs are built on top of strength work, not instead of it (2.5, 2.3). Accidental bulk is not a real risk; deliberate bulk takes years.

Unit 3 cheat sheet: speed, power and sport

How do I actually get faster?

Sprint short, sprint fresh, rest fully, repeat — and get stronger. Speed is a maximal-output skill, and skills are learned at full quality. Sprinting on tired legs rehearses slow mechanics; that is conditioning, not speed work, and the two should not be confused (3.4, 3.6).

How do I jump higher?

Three inputs: leg strength, jump practice at full intent, and landings you control. A handful of maximal jumps with full recovery does more than fifty tired ones, because the nervous system is the thing being trained (3.8).

How do I avoid pulling a hamstring?

Hamstrings fail when they are weak at long length and asked to sprint on fatigue. The protection is unglamorous: Nordic curls and Romanian deadlifts for long-length strength, regular exposure to actual sprinting, and respect for fatigue late in sessions (3.7).

Why am I fit in the gym but ordinary in games?

Because games are decided by perception and decision as much as output. Gym qualities set the ceiling; reading the play, reacting and changing direction decide how much of the ceiling you use. That gap — and how to close it — is the subject of 3.13 and 3.18.

Unit 4 cheat sheet: stiffness, stretching and joints

Why am I so stiff when I sit all day?

Tissue adapts to the positions it is held in, and for most people that position is a chair. The countermeasure is frequency, not heroics: brief movement breaks through the day and ten minutes of deliberate mobility work most days beat one long weekly stretching session (4.1, 4.2).

Stretch before or after training?

Before: dynamic work — leg swings, lunges, arm circles — to raise temperature and rehearse range (4.10). Long static holds sit better after training or at another time of day; parked directly before heavy lifting or sprinting they can blunt output (4.11).

Something aches when I train. Keep going?

Sharp, sudden or worsening pain: stop and get it assessed by a qualified clinician. A mild, familiar ache: reduce the load, slow the tempo, shorten the range to what you control, and strengthen around the joint — graded load usually beats total rest (4.4, 4.7). This is general information, not a diagnosis.

What actually improves mobility?

Consistency and load. Controlled articular rotations, full-range strength work and end-range holds change what a joint can do; passive stretching alone mostly changes how stretching feels. The methods are laid out across 4.13, 4.16 and 4.17.

Unit 5 cheat sheet: focus, drive and the feed

How do I get rid of brainrot?

Strip the slang and something real is left: a reward system trained by thousands of three-second novelty hits to expect stimulation without effort, and an attention system that has learned to bail the moment things get quiet. Both are learned, which is the good news — learned things can be retrained (5.16). Make the hits rarer and effort cheaper: phone in another room while you work, no feed in the first hour of the day, one task at a time held slightly past the urge to switch. Most people notice the fog lifting within two to three weeks. The mechanism — and why it reverses — is in 5.8.

Why can’t I focus for more than a few minutes?

Attention is partly a tolerance for boredom, and every reach for the phone during a dull moment trains that tolerance down. Rebuild it the way you would rebuild any capacity: on purpose, in doses. Walks without headphones. One screen at a time. Timed blocks of single-task work that get longer weekly. The prefrontal machinery this trains is described in 5.25; the pressure side of attention in 5.3.

Where did my drive go?

Drive is chemistry with a budget. Dopamine responds to anticipation and effort; flood it with effortless reward and effortful things stop feeling worth starting (5.7, 5.8). Alertness runs on orexin, which runs on sleep, daylight and regular meals (5.12). The repair program is dull and effective: guard sleep, get morning light, do hard things early in the day, and let rewards follow effort for a few weeks.

How do I stop doomscrolling at night?

Treat it as an engineering problem rather than a character problem. The feed is built by teams of engineers to defeat willpower at 11 p.m., so change the environment instead: charger outside the bedroom, the worst apps behind a timer, screens down before the lights are. The habit loop this interrupts — cue, action, reward — is the subject of 5.14; what late screens do to sleep is in 5.17.

How do I make a habit stick?

Shrink it until it is hard to refuse, anchor it to something you already do daily, and protect the streak loosely — missing once is noise, missing twice is the start of a different habit. Somewhere between one and three months the basal ganglia take over and the behaviour stops costing willpower (5.14, 5.15).

How to use this page

Skim the definitions once so the vocabulary stops slowing you down, then let the cheat sheets route you. Every answer above is the short form of an article that argues the case properly, with mechanisms and citations. When an answer here is enough, act on it. When it is not, the number beside it is the door.