Interference: An Intensity Technique Explained

When the target muscle undergoes strength and endurance training at the same time, i.e. within minutes or a few hours of each other, the rate of muscle protein synthesis is inhibited compared with strength training alone. The neural component of strength, however, is trained just as well. If you want more “strength” but not necessarily more muscle mass, you can benefit from this kind of combined training.

The training weight is moved 6 - 10 times in a 3-2-3-2 rhythm (concentric - isometric shortened - eccentric - isometric stretched). This gives a time under tension of 60'' - 100''. Straight after the full strength-training set, the target muscle is exposed to a high level of energy stress during an endurance session. This energy stress triggers interfering molecular processes that inhibit the rise in muscle protein synthesis. Meta Training (high-intensity interval training) is particularly well suited for the endurance part.

Terminology

Interference

is an English word meaning impairment. Here it refers to the impairment of muscle protein synthesis, and therefore of muscle growth.

concentric

A concentric muscle contraction occurs when a muscle shortens while exerting force – for example, lifting a weight or accelerating an object. In doing so, the muscle performs physical work.

isometric

The force increases while the muscle stays the same length (holding-static). In the physical sense, no work is done, since the distance covered is zero.

eccentric

Here the resistance is greater than the tension in the muscle, so the muscle lengthens (negative-dynamic, yielding); the muscle "brakes" a movement in the process. This causes changes in tension and lengthening/stretching of the muscle. This form of load, or contraction, occurs for example in the front thigh muscles (M. quadriceps femoris) when walking downhill.

Rate of muscle protein synthesis

The rate at which muscle protein is produced.

Source: update Fitness training concept and Wikipedia