"Your spine is anchored by a series of muscles and tendons that work together from several different angles in your body. Overworking muscles on one side without spending equal attention on the opposing muscle group can create a muscular imbalance that can affect your performance severely."
There’s more to flat abs than crunches
"I train so many women who are shocked when I tell them crunches can't do it all. Think about it: You wouldn't limit yourself to doing lunges for your legs or push-ups for your arms, right? You need to mix in other moves."
Mix It Up
"Keeping your muscles from getting bored doesn't mean scrounging up an all-new routine. Constantly making small tweaks to the same moves is enough."