C - Being fit; technology

To improve her fitness, she decided to (a)   by doing regular workouts. (Phrasal verb; become stronger and firmer)

He wants to (a)   before the rugby season starts by increasing his protein intake. (become more muscular; phrasal verb)

After the holiday indulgence, it's time to (a)   weight and get back to exercising regularly. (lose)

She runs three times a week to build (a)   for the upcoming marathon.

To gain muscle, he plans to (a)   weights at the gym every other day. (other than lift)

She incorporates (a)   into her routine to strengthen her core. (a core exercise designed to strengthen your abdominal muscles)

(a)   are an essential part of her workout because they help strengthen her legs. (a kind of exercise with the knees bent and the weight on your feet.)

(a)   before a run is important to prevent injuries and improve flexibility.

He has decided to (a)   that limits carbohydrates to boost his health.

If you don't stretch properly, you might (a)   a muscle during your workout. (or strain a muscle, when you overstretch or tear a muscle)