Isometric Training for Muscle Growth
Very few bodybuilders routinely use isometric training to improve strength because they feel that the studies which have been done show increased strength gains without muscle gains. But bodybuilders are missing out on an important technique to increase both strength and muscle size.
Any isometric muscle activation is the action of strength/muscle tension that does not result in movement of either the weight/ resistance lifted or the lengthening/shortening of the muscle. For example, holding a dumbbell at mid-range for 60 seconds or more.
Isometric training could also be as simple as pushing with everything you got against a brick wall. But something that bodybuilders ignore is that isometric training results in a contraction regimen that recruits more muscle fibers than any concentric or eccentric movement done with weights.
In a study recently completed to examine this difference in muscle fiber activation it was clearly shown that a person is able to recruit at least 5% more muscle fibers called motor units than any eccentric (lowering) or concentric (lifting) movement with weights.
Farther study on exactly how many of these motor-units were activated using isometrics revealed that almost all the muscle fibers in a given body-part are activated when using maximal force. This tells us that isometric training will improve motor-unit recruitment and the neural drive required to lift a weight could be dramatically improved.
Another study done on isometric training clearly showed significant strength gains ranging between 14% to 40% over the ten-week period that the study was done using isometric training. The results of this specific study were then examined a little more closely.
They found that when comparing isometric training with normal weight training, normal weight training produced a maximum intramuscular tension for 0.25 to 0.5 seconds doing concentric movement but when doing any isometric training the tension can be sustained maximally for 3 to 6 seconds.
Time under tension (TUT) increases strength so adding 10 or even 20 seconds doing isometric training will significantly improve strength. Isometric training can be done at any point in the full range of motion (ROM) which could make a significant difference to help any bodybuilder break through a training plateau.
Isometrics are not "energy expensive," this means you don't need a lot of energy to perform isometrics and they can be easily included in any bodybuilders workout. If you think it will not increase your muscle size, then you need to read the details of a study done by Kanchisa et al in 2002.
The extensive study clearly showed that the average cross-sectional area of the muscle (size) improvement was 12.4% shown in all the participating volunteers doing maximal isometric contractions. The volunteers doing 60% maximal training showed a 5.3% increase in muscle size after ten weeks.
In conclusion, the important study mentioned above that showed significant muscle gain in ten weeks was attributed to the metabolic and endocrine demands when doing isometrics, by the authors of the study. Isometric training should be seriously considered by any bodybuilder trying to gain muscle.