Running economy

Running economy is the oxygen or energy cost of running at a given submaximal speed. Lower cost at the same speed indicates greater economy.

Running biomechanics: The study of the forces and movements involved in running. Stride mechanics influence the energy required to cover each metre.
Submaximal exercise test: An exercise assessment performed below maximal effort to measure physiological responses to a set workload. Running economy is commonly measured while speed stays below maximum.
VO2 max: The highest rate at which a person can take up and use oxygen during intense exercise. It sets an aerobic ceiling; economy concerns the cost of running below that ceiling.
Endurance running: Running over distances that require sustained aerobic effort. Lower cost can allow a runner to maintain a faster pace at a given aerobic capacity.
Stretch-shortening cycle: A muscle action in which rapid lengthening precedes shortening, allowing elastic energy to be stored and reused. Tendons can return stored energy during each running stride.
Indirect calorimetry: A method that estimates energy expenditure from oxygen consumption and carbon dioxide production. It provides the oxygen-use measurements used to quantify running cost.
Critical speed: The highest constant exercise intensity that can be sustained without continual exhaustion. It predicts sustainable pace, unlike oxygen cost at one fixed speed.
Marathon: A road race covering 42.195 kilometres. Economy matters over this distance because small differences in cost accumulate over many steps.
Tendon: A band of connective tissue that attaches muscle to bone and transmits force. Tendon stiffness and recoil affect how much metabolic work a stride requires.
Lactate threshold: The exercise intensity above which blood lactate rises more rapidly than it can be cleared. It describes sustainable intensity, whereas economy describes cost at a specified speed.

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