Mother-of-two Katarzyna Wysokinska, from Garston, said the free membership would be welcomed by her 16-year-old gym-obsessed son.
She said: “At the moment we are paying over £30 per month for him to be a member of our nearest gym.
“If he does want to go to the gym and stay healthy and stay out of trouble, it costs us.
“My husband and I both work full-time, earning above minimum wage, and the price of sports for both our children is going up and up along with everything else”.
Describing the scheme as “amazing for young people”, she suggested it could help keep teenagers “off the street”.
However, she conceded that for some existing Lifestyles members, the potential for teenagers to be disturbing their tranquil weekend swim could be an issue.
In response Doyle said the scheme would be monitored and the council would “make sure there is space through the day for everybody”.