Get stronger before you go faster before you go longer.
Eventually, overtime, those tight muscles tug at your pelvis and spine and then the entire kinetic chain gets thrown off. You begin to feel nagging aches and pains in your shoulder, lower back and even your feet and calves.
You now you notice that your not able to hit your intervals/zones like you did a few days/weeks ago and as your gait or pedaling or swim stroke becomes sloppy, you convince yourself that you just need to push harder. So, as a dedicated, hard working athlete, you refuse to throw in the towel so you continue to push on until it's too late.
Now your body is completely out-of-whack and you aren't quite sure where to start to get yourself healthy again.
I hear it all the time from injured athletes "As soon as I get better, I will strength train more often and stretch more after workouts."
Even though you know that core/hip/glute work will reduce the chance of injuries and will improve stability, balance, power and speed, cardio training typically takes precedence when athletes are training and strength training and stretching are the first two things to get pushed aside.
Have fun getting stronger!
Always consult with your physician before trying a new or different exercise routine.
Hold 3 x 30-60 seconds w/ rest as needed. Keep core tight and don't forget to breath.
3 x 20-30 seconds w/ rest as needed.
Push-ups with medicine ball under feet and medicine ball under one hand (then switch hands). You must have healthy shoulders/upper back to perform this exercise.
Trying out for the circus (most advanced)
Push-ups with medicine balls under feet and medicine balls under hands.
You should be able to do 10 good-form crunches at a decline before trying this exercise.