Estudio: Entrenamiento para cada tipo de fibra

[Hiperius]

Aqui os dejo un estudio de 2002, del que se ha hablado bastante en el foro durante años, pero bueno, para los foreros nuevos que no lo conozcan, aqui os lo dejo. El estudio compara 3 tipos de entrenamiento para comprobar como influye el rango de repeticiones en el crecimiento de las fibras musculares tipo I, IIA y IIB:

Now, I will refer people to a study that was done comparing 3 different routines. (Campos GE, Luecke TJ, Wendeln HK, Toma K, Hagerman FC, Murray TF, Ragg KE, Ratamess NA, Kraemer WJ, Staron RS. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. Eur J Appl Physiol. 2002 Nov;88(1-2):50-60.) They used an 8-week high-intensity training program for the legs. Workouts were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. The subjects used one of three different regimens. The different training regimens were designed to be approximately equal in volume (resistance x repetitions x sets) with the rest periods between sets and exercises adjusted according to the strength-endurance continuum. Therefore, those individuals working on the high-rep end of the continuum performed fewer sets and had shorter rest periods compared with the other training groups.

The exercises were performed in the fixed order of leg press, squat, and knee extension. After warming up:

· The Low-Rep group used their 3-5RM for four sets with 3 min rest between sets and exercises.

· The Intermediate-Rep group used their 9-11RM for three sets with 2 min rest.

· The High-Rep group used their 20-28 RM for two sets with 1 min rest.

During the study, the resistance was progressively increased as subjects were able to perform more reps in order to ensure subjects were always using their true RM for each rep range.

So what happened? Did the type-I fibers increase most in the high-rep group? Did only the type-II fibers hypertrophy in the low rep group? If you believe you must do high reps for type-I fibers to grow and low reps for type-II fibers to grow then that’s exactly what should have happened!

On the other hand, if hypertrophy is a matter of load, and all fibers hypertrophy in response to increasing load, then hypertrophy should go up as load goes up. In other words the group that lifted the heaviest relative weight should have experienced the greatest amount of hypertrophy in ALL fiber types irrespective of the number of reps (within reason). And that is exactly what happened.

Here is a breakdown of the hypertrophy caused by each rep range. [Remember, each group trained to failure regardless of RM used so muscular fatigue was equal between groups.]

High-Rep (20-28RM)
Type-I
· pre = 3894 post = 4297 (10.3% increase)
Type-IIA
· pre = 5217 post = 5633 (8.0% increase)
Type-IIB
· pre = 4564 post = 5181 (13.5% increase)

Med-Rep (9-11RM)
Type-I
· pre = 4155 post = 4701 (13.1% increase)
Type-IIA
· pre = 5238 post = 6090 (16.3% increase)
Type-IIB
· pre = 4556 post = 5798 (27.3% increase)

Low-Rep (3-5RM)
Type-I
· pre = 4869 post = 5475 (12.4% increase)
Type-IIA
· pre = 5615 post = 6903 (22.9% increase)
Type-IIB
· pre = 4926 post = 6171 (25.3% increase)

Should this surprise anybody? No! Higher loads with equivalent volume leads to greater hypertrophy regardless of fiber type. It also doesn’t surprise me that these researchers were confused by the fact that the low rep group had as much or more hypertrophy that the other groups. They too have the idea cemented in their brain that you can’t use heavy weight to stimulate hypertrophy. The strength training dogma of the past has deeply influenced even the research community with regard to hypertrophy. This has done nothing but hinder their progress in understanding it because they end up designing studies on false premises.

I’m not sure why people are so hesitant to accept the preeminence of load for producing hypertrophy. Perhaps it is that they fear not growing as fast as they think they can.

It would be of much greater benefit for people to discuss issues of fiber type with regard to muscle “performance” (i.e. strength/endurance/power). After all, the very distinctions themselves are based on how the fibers used fuel, not how they respond to load. Hence, basing predicted hypertrophic outcomes on the metabolic characteristics of a fiber will never lead anybody to a correct understanding of the mechanisms of hypertrophy.

- Bryan Haycock

Fuente: http://www.hypertrophy-specific.info/cg ... =13;t=4634