So im in my 30's now, nearly 31 and for years have focused on mainly sprint training, im not fast but its the thing im best at as i suck at endurance. However endurance type events (5k) are events i can do where i wont come last since you get all abilities (such as people who walk). With sprinting im last all the time in meets but i have more speed than endurance. Im 14.6 at 100whereas 5k im about 31 mins lol. Id like to improve at 5k as well as sprints however Ive heard that doing long distance runs will hinder sprint speed/fast twitch fibres. What do you think? Could I get better at both with more effort? Or is it a case of picking one or the other?