Concept
Threshold training
Controlled training near the transition where sustained effort begins to create rapidly increasing fatigue. Its purpose is to improve durable high aerobic output without turning every session into a race.
What it develops
Threshold training helps a runner sustain a stronger aerobic output while managing accumulating fatigue. The adaptation comes from repeatable time near the target intensity, not from reaching exhaustion.
Continuous and interval formats
The work can be a continuous tempo-style effort or cruise intervals separated by short recoveries. Intervals often make it easier to accumulate useful volume while keeping pace, heart rate, and technique controlled.
Dose and recovery matter
The appropriate amount depends on training history, weekly load, and the rest of the program. Threshold work has a meaningful recovery cost and should not displace easy running or become the default intensity.
Control is the quality standard
Good threshold training remains stable and repeatable. If pace fades sharply, breathing becomes uncontrolled, or the final repetition requires racing, the session has likely moved above its intended purpose.
Choose a repeatable intensity, finish with some reserve, and progress total controlled work gradually before trying to run it faster.
Threshold training is not all-out, not every hard run, and not automatically better when performed more often.