Using Eccentric Exercise to Target Fast Twitch Muscle Fibers

As we age we lose progressively more muscle mass each year, and specifically we lose fast-twitch muscle fiber.     Once this progresses beyond a certain point people are not longer able to perform common activities of daily living like getting up and down from chairs, walking up and down stairs, etc.

Use eccentric-dominant strength training to target fast twitch fibers and build muscle. Older adults over 60 will benefit from this style of training because it allows you to counter the age-related loss of fast-twitch muscle fiber.

A study in Medicine and Science in Sports and Exercise compared the effects of an eccentric-dominant resistance training protocol with a traditional training program in older individuals who had an average age of 68. Training was twice a week for 16 weeks, and the traditional protocol involved two sets of 10 reps at 75 percent of the 1RM using four exercise for the major muscle groups. The eccentric-enhanced training involved a unique training scheme. Participants performed three sets of 10 using a weight of 50 percent of the 1RM. They performed the concentric portion of the lift bilaterally (using both sides at the same time) and the eccentric portion unilaterally (using one arm or leg at a time), alternating between left and right limbs for each repetition and performing five eccentric contractions per limb per set.  

The eccentric-enhanced group had greater increases in strength at higher movement speeds, indicating greater fast twitch muscle development. The traditional training group gained strength as well but at slower movement speeds, which is expected because relatively heavy weights and slow speeds were used in the traditional training style. Eccentric training is excellent for this population because the increased strength at fast movement speeds and recruitment of fast-twitch muscle fibers is an advantage when rapid movements of the limbs are necessary, such as when recovering from a stumble or trip.

Additionally, eccentric training is well known for increasing hypertrophy, making it an ideal antidote for age-related muscle loss. This training style was also proven to be better for improving performance on “functional” tests that may be applicable to everyday life such as the speed at which one can walk six meters. The eccentric-enhanced group improved more than the traditional group, while a control group had a significant decline in walking speed on a six-meter walking test. This rapid decline in the control group is surprising because the population was a healthy community-dwelling group that was fairly active. Researchers suggest strength training is critical for older people because without it, there will be a rapid and pronounced functional loss.

There was also evidence of greater muscle hypertrophy in the quadriceps from eccentric-enhanced training than traditional. In fact, the vastus lateralis, one of the quad muscles increased in thickness in the eccentric group only, while the control group had a decrease in the thickness of this muscle, indicating sarcopenia at work.

Of interest, the rating of perceived exertion was lower in the eccentric training group. This is good news for older individuals, anyone who is new to exercise or bored with their workout. 

The reACT Trainer is the ideal for this purpose because it is a functional exercise that is eccentric-dominant and simultaneously improves balance, timing, coordination AND eccentric strength leading to rapid improvement in functional capability with increased fast-twitch muscle fibers.