Table 1

Descriptors of physical activity

Intensity	Objective measures	What patient feels*	Typical examples
Sedentary	<1.6 METs <40% HRmax <20% VO₂max	▸ At rest with limited added movement	▸ Sitting and reading ▸ Watching TV ▸ Driving a car
Light	1.6–3.0 METs 40–55% HRmax 20–40% VO₂max	▸ Active ▸ No noticeable change in breathing/sweating ▸ Can be sustained for 1 hour or more	▸ Slow walking (eg, around the house) ▸ Light work while standing (eg, cooking, washing dishes) ▸ Playing an instrument
Moderate	3–6 METs 55–70% HRmax 40–60% VO₂max	▸ Increased breathing and sweating, but ▸ Still able to maintain a conversation ▸ Can sustain activity for 30–60 min	▸ Brisk walk ▸ Low movement racquet games (eg, doubles tennis, recreational badminton) ▸ Water aerobics ▸ Resistance exercise ▸ Mowing the lawn
Vigorous	6–9 METs 70–90% HRmax 60–85% VO₂max	▸ Feeling ‘out of breath’ ▸ Increased sweating ▸ Can be difficult to maintain a conversation ▸ Can sustain activity for up to 30 min	▸ Jogging ▸ Hiking ▸ Swimming with effort ▸ Higher movement racquet games (eg, singles tennis and squash) ▸ Field/ball games (eg, soccer and basketball) ▸ Cross-country skiing ▸ Shovelling
High	≥9 METs ≥90% HRmax ≥85% VO₂max	▸ Feels like giving 100% ▸ All-out bursts of between 1 and 2 min ▸ Intensity cannot be sustained for more than 10 min	▸ Training/competing in most competitive sports ▸ Racing or any all-out activity (eg, running, rowing, swimming, skiing and high-intensity intervals)

*These descriptions do not generally apply for symptomatic patients with chronic obstructive pulmonary disease. MET values for high-intensity activity may not be achievable for many patients with chronic disease, in which case HRmax or VO₂max values are advised.
HRmax, theoretical maximal heart rate: usually estimated as (220−age)×0.9; MET, metabolic equivalent of task (1 MET=the energy to lie/sit quietly); VO₂max, maximal oxygen uptake (adapted from Norton et al).65