Women's fitness has come a long way since skinny defined the ideal body and a muscled arm was cause for alarm. Fitness experts say as strong becomes the new sexy the gender divide has narrowed, if not closed.
From resistance training to power workouts such as barbell squats, medicine ball throws and kettlebell swings, a rigorous regime has become more popular with women.
"We want women who want to turn it up a little bit," said Dean Hodgkin, a fitness writer and martial artist who co-authored the book "Better Body Workouts for Women" with fitness consultant and nutritionist Caroline Pearce.
"We specifically included heavy resistance and weight training formats because if women don't train heavy, they'll miss the opportunity to gain strength," said Hodgkin, who is based in Leicestershire, England.
Along with advice on executing workouts from hula hooping to power hopping, the book also dispenses guidance on issues like training before, during and after pregnancy, eating issues and mind games that can undermine progress. "These are times when women let it all fall apart," he explains. "There's no question that self confidence is more of an issue for girls."
Jessica Matthews, an exercise physiologist with the American Council on Exercise, doubts if a women's fitness book filled with power drills would exist 10 years ago.
"Now you see this all the time," said Matthews, noting women are eager to embrace tough workouts like CrossFit. Having a well-defined physique, she said, has replaced skinny as an ideal.
"A fellow yoga teacher mentioned to me the other day that she was excited and proud to be able to perform barbell squats (with the barbell positioned across the back of her shoulders) with great form using 225 pounds (102 kilos)," Matthews said. When she started teaching group fitness 14 years ago, it was rare to have a man take a class.
"The shift in the industry is interesting to see," she said. "(Today) there are no specific exercises for men or women. The type of exercise is based on person, not gender. I like to think we've moved on."
Dr. Michele Olson, an expert with the American College of Sports Medicine (ACSM), said women tend to be weaker than men because they are smaller and have less muscle mass. But given the same strength-developing exercise program, she said, women can become just as strong in the upper body and almost as strong, about 80 percent, as men in the lower body. "The principles are the same whether you're a man or woman in terms of how exercise is prescribed and the results that are realized," said Olson, a professor of exercise science at Auburn University in Montgomery, Alabama.
Give men and women the same exercise prescription for cardio fitness and they will improve to the same extent, she said, adding that heart disease is the number one killer for both sexes.
ACSM guidelines call for all adults to engage in cardio exercise at least three to five days a week, along with two to three days of strength training and two-to-three days of flexibility training. For strength training, Olson said, both men and women should lift weights that are heavy enough to exhaust the exercised muscle in no more than 12 to 15 repetitions.
"This will make you stronger," said Olson. "If you want to add muscle you need to lift heavier weights." Experts say the fear that women who weight train will suddenly sprout bulging muscles is unfounded. "Women, and most men, have a terribly hard time bulking up," Olson said.