As many as 14% of adults go a whole month without taking even a 10-minute walk, according to Government statistics.
As many as 24% of men aged 65 and over, and 27% of women in this age bracket, also do not have a monthly 10-minute stretch of legs, the figures showed.
Relating to England, the statistics - for 2013/14 - also showed that the proportion of the population who cycled at least once a month was 15% - the same as in 2012/13.
The cycling figure for London, where there have been eight cyclist deaths so far this year, has dropped from 15.7% of the adult population who got on bikes once a month in 2010/11 to 14.2% in 2013/14.
From the Department for Transport , the statistics showed:
:: 86% of adults walk (for at least 10 minutes) once a month for any purpose, with 57% in Cambridge walking at least five times per week;
:: The most frequent walkers are those aged 16-24, with 92% of men and 94% of woman of this age walking once a month;
:: Up to the age of 44, women tend to walk more than men;
:: 47% of all adults walked at least five times a week and around 3% cycled at least five times a week;
:: Men aged 16-24 and aged 35-44 cycle the most, but just 8% of men aged 65 or more, and only 3% of women, get the bike out at least monthly;
:: There were increases in cycling rates in 35 local authorities between 2012/13 and 2013/14 with Cambridge again to the fore, with 28% of the adult population cycling at least five times a week and 57% taking to two wheels at least once a month;
:: Although cycling rates have dipped in London, levels in 10 of the inner London boroughs are above the national average and go as high as 24%;
:: But 15 of the outer London boroughs are below the national average, with the once-a-month cycling rate dipping as low as 5% in Harrow.
The figures were based on a survey administered by Sport England and used to derive official estimates of participation in sport and active recreation.