Metabolic equivalent (MET)

A metabolic equivalent (MET) expresses an activity’s energy cost as a multiple of the rate used while sitting at rest.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 351.} One MET is conventionally set at an oxygen uptake of 3.5 mL/kg/min.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 351.} A 4 MET activity uses four times the energy of rest.^{2Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 446.}

ACSM’s screening categories classify exercise intensity as light at 2 to 2.9 METs, moderate at 3 to 5.9 METs and vigorous at 6 METs or more.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 166.} Published tables put light or moderate free-weight training at 3.0 METs, walking at 3.5 mph at 4.3 METs and running at 6 mph at 9.8 METs.^{4Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 581.}

How do trainers use METs?

• Track weekly volume in MET-minutes (METs multiplied by minutes); ACSM considers 500 to 1,000 MET-minutes a week a reasonable target for most adults, roughly 150 minutes of moderate activity.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 351.}
• Estimate calorie use with this formula: kcal per minute = (METs × 3.5 × body weight in kg ÷ 1,000) × 5.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 351.}
• METs are absolute values that don’t account for age or fitness: an older client at 6 METs may be at vigorous-to-maximal effort while a younger client at the same value is at moderate effort.^{5Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 347.} Relative measures such as heart rate reserve suit individual prescription better.^{5Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 347.}
• Prescribing a percentage of a client’s maximal METs requires a maximal graded exercise test first.^{2Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 446.}