For years, the weight room — with its dumbbells and Nautilus equipment — seemed to be the domain of the young, male aspiring body builder, guys anxious to sweat and struggle for gargantuan muscles. If your exercise plan was to shed excess bulk rather than build more muscle, the best options appeared to be a walk on the treadmill or a ride on the stationary bike.

But enter a gym today, and chances are you’ll find some new faces amidst the barbells. People of all ages and both genders have the physical ability to improve their health in the weight room, according to researchers at Ohio University and elsewhere. Women and senior citizens who train can gain strength and muscle fiber at the same rate as young men, and all lifters can lose body fat and boost their energy levels.

Another benefit that may be sending more people to the bench press is the quick payoff. New studies suggest that molecular changes in the muscle begin within two to four weeks of initiating resistance training, far earlier than previously thought. These and other findings, many of which point to strength training’s various health benefits, are encouraging news for those curious about crossing the fitness center divide between the treadmills and weights.

Before the 1980s, there were few studies on the impact of weight training on women’s strength and fitness, perhaps because women were concerned about growing bulging muscles, says Robert Staron, an associate professor of anatomy. Staron and his colleagues wanted to fill the research gap, and called untrained male and female college students into the gym and asked them to undergo eight weeks of rigorous leg muscle exercises. 

Women gained strength and muscle fiber at the same percentage rate as the men, the researchers found. “When our study was published, people didn’t believe our results, because people didn’t believe women could get that strong,” says Staron, himself a recreational weight lifter. 

But the Ohio University team had medical data to back up its observations of female vigor. The researchers extracted blood samples and raisin-size biopsies of muscle tissue from the thighs of their subjects to examine changes inside the body. It’s a method they’ve used for more than 25 years in studies involving about 100 men and 60 women, work that has been supported by a variety of sponsors, including the NASA Center for Cell Research, the Ohio Board of Regents, and the American College of Sports Medicine, to name a few. The technique has allowed them to learn more about muscle growth in both genders.

Many people assume that weak muscles, brittle bones, and failing health are common and inevitable symptoms of old age for men and women. Results from a small study of elderly men dispute this, however, suggesting that weight training can keep seniors strong and can improve their quality of life, says Robert Hikida, a Distinguished Professor of anatomy at Ohio University.

Hikida and his colleagues found that eight elderly men who performed high-intensity leg exercises could gain strength at the same rate as untrained young men. In some instances, their stamina rose 100 percent over a 16-week study period. Even though the seniors didn’t match their younger counterparts’ heft, researchers noted a growth of 30 percent to 40 percent in the muscles of older participants. The difference in muscle size between the ages was probably due in part, Hikida says, because the seniors started the training program with smaller, less developed tissue.

Despite these positive results, researchers found that seniors may not be able to rebuild muscle mass to the extent that young people can. And the elderly face another limitation — it takes longer for older muscle to recover from each weight training session. “Muscle repair is a very important process because any time you undergo a change in activity, you get soreness and muscle damage, and this tends to prevent people from continuing,” Hikida says, referring to all fitness seekers — not just the elderly.

In a new study of old and young adult rats that run 90-minute stints on a treadmill, Hikida and his colleagues are examining whether age-related changes to immune system cells involved in natural muscle repair could be the culprit. If so, researchers could find ways to boost the activity of those cells to speed the repair process in the elderly.

A little muscle ache may be a small price to pay for all the health benefits weight training can offer. The mild burn felt the morning after leg squats and triceps extensions may just be a reminder of all the good physiological changes happening in the body — changes documented in journal articles published by these researchers. Weight training not only increases physical strength, Staron says, but has no negative impact on cholesterol levels and helps reduce body fat.

That’s sure to catch the attention of fitness-minded folks who think that exercise such as walking on a treadmill is the only way to drop extra pounds and boost aerobic capacity. Health experts have long thought that weight training had a marginal impact on the cardiovascular system, says Fredrick Hagerman, a professor of physiology at Ohio University. But he and his colleagues have found that weight lifting can prompt muscles to consume more oxygen, allowing the body to produce more energy.

“There’s no mystery in why people feel better — they’re taking in more oxygen, getting stronger,” says Hagerman, also a fitness enthusiast. “That grocery sack becomes relatively lighter.”

Hagerman, who has been studying the physiology of Olympic rowers since 1966, stresses that people needn’t be professional athletes to endure — and reap the health benefits of — rigorous strength training exercises. One thing that has set the Ohio University studies apart, he points out, is that their routine requires participants to exercise at up to 90 percent of their maximum physical effort. Their research has shown that an average person has much greater strength capacity than most people would believe. 

Now the researchers are turning their attention to how specific resistance training regimens impact strength and endurance. That includes a study of a conventional leg press machine and home fitness equipment, as well as comparison studies of high- and low-intensity weight lifting routines. Building on their research of the last few decades, the scientists want to add to their understanding of muscle development and fine tune their knowledge of the impact of weight training. But for the average healthy gym-goer, the work simply offers yet another reason to break into the barbell business. 

Andrea Gibson is assistant editor of Perspectives. Jo McCulty is a freelance photographer in Columbus, Ohio.