Even low levels of weekly exercise drive down blood pressure and boost overall fitness, suggests a small study in the Journal of Epidemiology and Community Health.
To stave off ill health, adults are currently recommended to indulge in 30 minutes of moderately strenuous exercise on at least five days of the week.
But few people meet these recommendations, with lack of time cited as the most common reason for failing to do so.
The study authors invited 106 healthy but sedentary civil servants between the ages of 40 and 60 to take part in an exercise programme for 12 weeks.
Some 44 people were randomly assigned to 30 minutes of brisk walking on five days of the week.
A further 42 were given the same programme, but for three days of the week. And the remainder were not asked to change their current lifestyle.
Pedometers were used to help participants monitor their walking and every participant recorded how long they walked for.
Blood pressure, blood cholesterol, weight, hip and waist girth, and overall fitness (functional capacity) were all measured at the start and finish of the 12 week study.
Most people (89%) lasted the course.
There were no changes in any of the measures among the non-walkers. But systolic blood pressure and waist and hip girth fell significantly in both groups of walkers.
Overall fitness also increased in the walkers.
Falls of a few mm in blood pressure and shrinkage of a few centimetres in hip and waist circumference are enough to make a difference to an individual's risk of dying from a cardiovascular disease, say the authors
Furthermore, the findings show that moderate intensity physical exercise below the recommended weekly levels still makes a difference to health, they add.