Table:
Norm	Description
Dutch Norm for Health-enhancing Physical Activity (DNHPA)	Adults (18-54 years):
Thirty minutes or more of at least moderate-intensity aerobic (endurance) physical activity (≥ 4 MET; combined intensity score SQUASH ≥ 3) on at least five days each week.
Adults (55 years and older):
Thirty minutes or more of at least moderate-intensity aerobic (endurance) physical activity (≥ 3 MET; combined intensity score SQUASH ≥ 3) on at least five days each week.
Fit-norm	Adults (18-54 years):
Twenty minutes or more of vigorous-intensity physical activity (≥ 6.5 MET; combined intensity score SQUASH ≥ 6) on at least three days each week.
Adults (55 years and older):
Twenty minutes or more of vigorous-intensity physical activity (≥ 5 MET; combined intensity score SQUASH ≥ 6) on at least three days each week.
Combi-norm	Meeting at least one of the previous mentioned norms (i.e. the DNHPA or Fit-norm).

Translate the table into Markdown format.

| Norm | Description | 
 | --- | --- | 
 | <ROWSPAN=4> Dutch Norm for Health-enhancing Physical Activity (DNHPA) | Adults (18-54 years): | 
 | Thirty minutes or more of at least moderate-intensity aerobic (endurance) physical activity (≥ 4 MET; combined intensity score SQUASH ≥ 3) on at least five days each week. | 
 | Adults (55 years and older): | 
 | Thirty minutes or more of at least moderate-intensity aerobic (endurance) physical activity (≥ 3 MET; combined intensity score SQUASH ≥ 3) on at least five days each week. | 
 | <ROWSPAN=4> Fit-norm | Adults (18-54 years): | 
 | Twenty minutes or more of vigorous-intensity physical activity (≥ 6.5 MET; combined intensity score SQUASH ≥ 6) on at least three days each week. | 
 | Adults (55 years and older): | 
 | Twenty minutes or more of vigorous-intensity physical activity (≥ 5 MET; combined intensity score SQUASH ≥ 6) on at least three days each week. | 
 | Combi-norm | Meeting at least one of the previous mentioned norms (i.e. the DNHPA or Fit-norm). |