Improving muscular strength and endurance slows bone density loss.

True.

A study has been conducted and suggested that indeed improving muscular strength and endurance or exercising can enhance bone density and stop it from declining whether its due to accidents or old age. Also, because this practice is needed to have stronger and more healthier bones, exercising is always a necessity and should be a habit. 

The negative effects of smoking weed underage age includes:
regular use
heart problems
trouble breathing
mental health issues
academic issues
lower life satisfaction