Terms

Achilles tendinitis is inflammation or degenerative damage to the Achilles tendon (which connects the calf muscle to the heel bone) — a typical overuse injury among runners, especially with a sharp increase in volume or intensity.

The aerobic zone is the intensity at which energy is produced predominantly using oxygen, without significant lactic acid accumulation. Roughly zones 1-2 by heart rate.

The anaerobic threshold (lactate threshold) is the intensity above which lactic acid starts accumulating in the blood faster than the body can process it.

The anaerobic zone is high intensity (usually above 90% of maximum heart rate), at which energy is produced without sufficient oxygen, with rapid accumulation of lactic acid.

DOMS (Delayed Onset Muscle Soreness) is muscle pain that appears not immediately, but 24-48 hours after unfamiliar or intense exertion, especially after eccentric work (for example, downhill running).

FTP (Functional Threshold Power) is the maximum power output in watts a cyclist can sustain on average for about an hour. It's a key fitness indicator in cycling, analogous to the anaerobic threshold (AT) in running.

Heart rate reserve is the difference between maximum heart rate and resting heart rate. The Karvonen method uses it to calculate zones more precisely than just a % of the maximum.

Heart rate zones are intensity ranges (usually 5 of them), expressed as a percentage of maximum heart rate, each corresponding to a specific type of training effect.

ITBS (Iliotibial Band Syndrome) is one of the most common injuries among runners: pain on the side of the knee caused by irritation of the iliotibial band (a dense ligament running from the pelvis to the shin) at the point where it rubs against the outer condyle of the femur.

Maximum heart rate is the highest number of heartbeats per minute the body is able to reach under maximal effort. The basis for calculating heart rate zones.

Overtraining is a state of chronic fatigue from accumulated training load without sufficient recovery, in which performance declines instead of improving, despite continued training.

Plantar fasciitis is inflammation or degeneration of the plantar fascia (a dense ligament running along the arch of the foot) — a common cause of heel pain in runners, especially sharp during the first steps after sleep.

Resting heart rate is the heart rate at complete rest, best measured in the morning right after waking up, while lying down, before getting out of bed.

Running economy is how much oxygen (and energy) is spent to maintain a given pace. A more economical runner uses less energy for the same speed.

VDOT is a running fitness indicator invented by coach Jack Daniels: an estimate of "effective VO2max" based on a real race result, also accounting for running economy.

VO2max (maximal oxygen uptake) is the largest volume of oxygen the body is able to absorb and use per minute of intense work. A key indicator of aerobic fitness.

Power in watts is an objective physical unit measuring the amount of work a cyclist performs per unit of time — unlike speed, it doesn't depend on wind, gradient, or road surface quality.