Weak pelvic floor muscles affects the ability to hold in urine and small leaks could occur during sudden exertion when the pressure in the abdomen is increased. This could happen during running, lifting heavy objects or other strenuous activities. 

 It is impossible to run and cross your legs to hold it! You would find it easier to concentrate and enjoy your running if you had the reassurance of using pads as protection. Not exercising could have a negative impact on the quality of your life.

 However, I suggest beginning a pelvic floor exercise program. "Sexhercise™ Essentials" an audio program that can be practiced in the comfort of your home.

Your pelvic floor muscles are like other muscles that need to be strengthened and toned. As with  all exercise programs with patience and commitment your will gain results. You should feel a difference within 8-12 weeks. If you are not getting stronger in 3 months consult with a women's health physical therapist or acupuncturist.