Electromyographical (EMG) Research and Exercise Selection
Electromyography allows physiologists and medical experts to determine the role of muscles during specific movements (3) Electromyography is a scientific method of measuring the level of excitation (electrical signal) of a muscle group. Muscle contraction is initiated by electrical charges that travel across the membrane of muscle fibers. This movement of ion flow can be measured on the skin by a surface electromyogram (SEMG) (2; 5) An SEMG provides a representation of the entire electrical activity of the motor units and the frequency of their firing rates for each muscle being examined (1; 4).
When creating your exercise program, you eventually come to a point where you need to select which exercises in particular you are going to perform. The results of the following EMG studies can be used as a tool to help you determine which exercises to choose. Regardless of your planned training volume or frequency, the EMG results are beneficial as they allow you to prioritize your exercises based on the amount of concentrated muscle stimulation.
Louis Melo’s Studies
The purpose of this series of studies was to find, through EMG recordings, which exercises cause the greatest amount of stimulation within each muscle group and, consequently, to determine which exercises will produce the greatest gains in mass and strength.
Methods
For each study, the subjects were both male and female bodybuilders and strength trainers who were free of neuromuscular disease, had at least 2 years of bodybuilding experience, and were free of performance-enhancing drugs for at least 2 years.
Testing was performed on two separate days. On the first day, 1RM was determined for all exercises. Each subject underwent a warm-up of 10 reps at 50% 1RM, 5 reps at 80% 1RM, and 2 reps at 90% 1RM, interspaced with a 5-minute rest interval between sets. 1RM was then performed 3 times interspaced with a 5-minute rest interval between each repetition. On the second day, the subjects performed 80% 1RM 5 times, interspaced with 3-minute rest intervals.
Electromyographical activity was measured during all exercises. All EMG data was rectified and integrated (IEMG) for one second. For each muscle, the exercise that yielded the highest IEMG determined at 1RM was designated as IEMG max for the specified muscle. IEMG at 80% 1RM was determined by taking the average of the five 80% 1RM trials.
Data was analyzed using two one-way repeated measures analysis of variance to determine which exercise yields the greatest percent IEMG max for each muscle. Differences among exercises were determined with the Newman post hoc test.
Results of EMG Research
The results of the EMG studies show which exercises produce the greatest amount of stimulation within each target muscle group. The following table displays these results.
Smith machine squats (90 degree angle, shoulder-width stance) 60
Biceps femoris (hamstring)
Standing leg curls 82
Lying leg curls 71
Seated leg curls 58
Modified hamstring deadlifts 56
Semitendinosus (hamstring)
Seated leg curls 88
Standing leg curls 79
Lying leg curls 70
Modified hamstring deadlifts 63
Gastrocnemius (calf muscle)
Donkey calf raises 80
Standing one-leg calf raises 79
Standing two-leg calf raises 68
Seated calf raises 61
The effectiveness of a program is strongly related to the exercises performed. Exercises that produce the greatest amount of electrical activity during muscular contraction will produce the greatest amount of muscular efficiency.
References:
1. DeLuca, Fj., R.S. LeFever, M.P. McCue, and A.P. Xenakis. (1982), “Behavior of human motor units in different muscles during lineally varying contractions” Journal Physiology (Lond), 329:113-128.
2. Kobayashi Matsui, H. (1983), “Analysis of myoelectric signals during dynamic and isometric contraction.” Electromyog Clin Neurophysiol, 26, 147-160.
3. Melo, G.L. and E. Cafarelli. (1994-95), Exercise Physiology Laboratory Manual, 25.
4. Moritani, T. and H.A. deVries. (1987), “Re-examination of the relationship between the surface integrated electromyogram (IEMG) and force of isometric contraction.” American Journal of Physiological Medicine, 57:263-277.
5. Moritani, T., M. Muro, and A. Nagata. (1986), “Intramuscular and surface electromyogram changes during muscle fatigue.” Journal of Applied Physiology, 60:1179-1185.
