NSCA’s Performance Training Journal: A free publication of the NSCA.

Increase Strength without an Increase in Size?

By Lee E. Brown, EdD, CSCS,*D

Resistance training results in strength gains. This has been known since early Greek times when Milo lifted cows. Since then, hundreds of experimental studies have agreed that gains in strength are the primary result of an increase in muscular size, referred to as hypertrophy. When a muscle gains size it also gains strength. What is less well known is the phenomenon that results in increased strength after only a few resistance training sessions. This has been observed in people without a long history of resistance training. It has been speculated that these “short-term effects” are the result of changes in neural factors rather than hypertrophy4. Experimental studies have shown that short-term resistance training can increase strength production in the absence of hypertrophy or muscle size. These early strength gains are largely attributed to an increase in the maximal muscle activation level. In other words, the untrained human system becomes more efficient at both sending and receiving the brain signals that cause muscles to contract prior to initiating growth of muscle.

De Lorme and Watkins3 were the first to suggest that the initial changes in strength following resistance exercise in untrained individuals occurs at a rate too fast to be accounted for by hypertrophy. In later work by Moritani and deVries5, they measured untrained subject's elbow strength in conjunction with neural signals from the brain. After the subjects trained for eight weeks in a progressive resistance, dumbbell exercise program, all of them had significantly increased their maximal strength. More importantly, the neural measurements indicated that changes in electrical activity at the elbow were primarily responsible for early strength increases while hypertrophy responses gradually increased over time. That is, the first factor that influences strength gains in untrained subjects is not size but brain signal efficiency.

A recent study1 also demonstrated short-term improvements in leg strength-speed can occur by increasing the amount of resistance training performed during the training time. This study increased the training volume and this increase in the amount of exercise performed contributed to the strength changes demonstrated by the subjects. However, when the muscle of the upper leg was measured via MRI at the conclusion of training, muscle fiber area revealed no changes. In contrast, the neural activity of the leg increased significantly. These results again point to a learned neural efficiency in untrained subjects as a function of resistance training.

Conclusion

The increases in strength associated with resistance training occur within a time frame that entails two primary factors2. First, neural changes occur within the human system that involve greater efficiency of signal transmission from the brain as well as an increase in the muscle’s ability to accept these signals and convert them into muscle contraction and therefore strength. Second, the actual size of the muscle increases over time, which also results in strength gains. Therefore, it is possible to gain strength without gaining size in untrained participants. Of course, all of this occurs within the constraints of the human hormone system, which varies with age and gender. We will discuss those factors in the next column.

References

Akima H, Takahashi H, Kuno S, Masuda K, Masuda T, Shimojo H, Anno I, Itai Y, Katsuta S. (1999). Early phase adaptations of muscle use and strength to isokinetic training. Medicine and Science in Sports and Exercise 31(4): 588 – 594.
Baechle TR, Earle RW. (Eds). (2000). Essentials of strength training and conditioning. Champaign, IL: Human Kinetics.
De Lorme TL, Watkins AL. (1951). Progressive resistance exercise. New York: Appleton Century, Inc.
Komi PV. (Ed.). (1992). Strength and power in sport. London: Blackwell Scientific Publications.
Moritani T, deVries HA. (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine 58(3): 115 – 30. 1979.

About the Author

Lee E. Brown, EdD, EPC, CSCS,*D, is Assistant Professor and Director of the Human Performance Laboratory at Arkansas State University. He received his Doctorate at Florida Atlantic University, where he was Health Sciences Lab Coordinator. Dr. Brown is a Fellow of the American College of Sports Medicine, a USAW Certified Club Coach and a Certified Strength and Conditioning Specialist with Distinction (CSCS, *D) with the NSCA. He will be exploring topics of human physiology each month in this column.

(Print version) (Return to the current issue)

Figures

There are no figures for this article.