Tempo Training

Tempo is written as a sequence of numbers such as 3-1-2-0. Reading left to right, the first number is the seconds spent lowering the weight, known as the eccentric phase; the second is the pause at the bottom; the third is the seconds spent lifting the weight, the concentric phase; and the fourth is the pause at the top before the next rep starts. A 3-1-2-0 squat means three seconds down, one second pause at the bottom, two seconds standing up, and no pause at the top before the next rep begins. Strength coach Charles Poliquin popularized this notation in the 1990s as a way to make lift speed as programmable as weight and rep count.

Slowing a phase down increases time under tension, the total number of seconds a muscle spends working during a set. A three-second eccentric roughly triples the tension exposure of that phase compared to a one-second eccentric at the same load, even though the weight on the bar stays the same. Longer tension exposure at a given load contributes to the hypertrophy response through mechanotransduction, the process by which mechanical tension in a muscle fiber gets converted into a growth signal, somewhat independent of how much weight is lifted.

Different tempo choices train different qualities. Slow eccentrics emphasize muscle damage and connective tissue loading, explosive concentrics train the nervous system to produce force quickly, and a paused bottom or top removes momentum so the target muscle does the work instead of elastic recoil. Programs mix these deliberately: a hypertrophy block might prescribe 4-0-1-0 tempo on accessory lifts, while a power block prescribes an explosive tempo like 2-0-X-0, where X means as fast as possible.