Octogenarian Muscles Don’t Get Stronger with Exercise

Octogenarian women were unable to increase muscle mass after a 3-month weight lifting program targeted at strengthening the thigh muscle, according to a new study from the Journal of Applied Physiology. The results are surprising because previous studies have found resistance training capable of increasing muscle mass, even for people who are into their 70s. An increase in muscle size translates to an increase in strength.

Still, the Ball State University study contained some good news: The octogenarians were able to lift more weight after the training program, likely because the nervous system became more efficient at activating and synchronizing muscles.

The American Physiological Society published the study, “Improvements in whole muscle and myocellular function are limited with high-intensity resistance training in octogenarian women.” The researchers are Ulrika Raue, Dustin Slivka, Kiril Minchev and Scott Trappe.

Aim: Strengthen Octogenarian Thigh Muscle

The experiment involved six women, all in their 80s, all of whom lived independently and came to the laboratory three times a week for three months. The women exercised on a machine designed to strengthen the thigh (quadriceps) muscle. They did three sets of 10 lifts, with a 2-minute rest period between sets.

The researchers measured the size of the women’s thigh muscle using an MRI, before the exercise program began and after it ended. They also took biopsies from the thigh muscles, which they used to track muscle changes at the cellular level.

The biopsies included both fast-twitch and slow-twitch muscle fibers. Fast-twitch muscles are high powered and explosive and are associated with anaerobic exercise. Slow-twitch are associated with aerobic tasks, including endurance exercise such as marathons.

Fast-twitch muscles are important in posture and balance and so may be of particular importance for the elderly, who are more prone to falls. When people do not use their muscles during a period of convalescence or with a sedentary lifestyle, the fast twitch muscles lose functionality and atrophy more quickly than slow-twitch.

From the muscle biopsies, the researchers isolated single muscle strands, both fast-twitch and slow-twitch. They measured the strength, speed and power of each fiber and examined the genetic profile of these strands.

No change in muscle strength

As a result of the exercise program, the octogenarians were able to increase the amount they could lift with their quadriceps by 26%. That was the good news. The bad news was that the pre- and post-training MRIs showed that the training did not change their muscle size. This was surprising because an earlier study had found that 70-year-old women gained 5% muscle mass with resistance training.