Exercise recommendation in Hong Kong

In 2001, the Hong Kong government has organised a campaign called "Healthy Exercise For All". The exercise recommendation for the adults is:

minimum of 30 minutes moderate-intensity aerobic exercise, 3 days per week (preferably 5 days). (90-150 minutes per week)
(http://www.lcsd.gov.hk/healthy/physical_fitness/b5/index.php)

Comparing it with 3 other countries: Australia, UK and US

1) Australia (http://www.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-phys-act-guidelines#guidelines_adults)

• minimum of 30 minutes moderate-intensity physical activity on most, preferably all, days" (210 minutes per week)

2) UK (http://www.nhs.uk/Livewell/fitness/Pages/physical-activity-guidelines-for-adults.aspx)

• minimum of 2 hours and 30 minutes moderate-intensity physical activity per week. (150 minutes per week)
• "also undertake physical activity to improve muscle strength on at least two days a week"

3) US (http://www.health.gov/paguidelines/pdf/adultguide.pdf)

• minimum of 2 hours and 30 minutes moderate-intensity physical activity per week. (150 minutes per week)
• "also undertake physical activity to improve muscle strength on at least two days a week"

Although it has mentioned "preferably 5 days per week" in the HK exercise recommendation, minimum of 3 days per week is suggested, which the amount of exercise is less than the minimum requirement for Australia, UK and US. Moreover, there is an additional guideline for the UK and US public to also strengthen the muscles rather than just cardiovascular fitness only.