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Are Eccentric Muscle Contractions Beneficial?

FIRE & Protein…perfect duo!

FIRE (Focused Intense Resistance Exercise) is a research-proven form of exercise that will really help you achieve the bodyshape you desire. It’s clear from research that protein supplementation enhances muscle protein synthesis [1]. In fact, it’s well established that whey protein supplementation immediately post-FIRE enhances muscle protein synthesis [2].

Two types of muscle actions

There are two types of contractions conducted during a FIRE exercise are eccentric (i.e., muscle lengthens while contracting) and concentric (i.e., muscle shortens while contracting).

There is some speculation that the mode of contraction (concentric vs. eccentric) may influence the degree of muscle hypertrophy.

We know that we can handle higher forces during eccentric compared to concentric contractions; consequently, the concentric strength will determine the absolute loading conditions during conventional FIRE that utilizes both types of muscle actions.

For example, the amount of weight used to lower the bar on a biceps curl (an eccentric action of our biceps muscle) is greater than what we can handle to raise the bar on a biceps curl (a concentric action of our biceps muscle). Therefore, the amount of weight we can use to raise the bar on a biceps curl determines the load used during FIRE utilizing both concentric and eccentric contractions.

Although there is speculation of one type of muscle action being preferred over the other; there is no research that shows eccentric only contractions enhance muscle hypertrophy with a prolonged training program.

What about tendons?

It’s clear from scientific research that tendons also respond to FIRE training [3]. In addition to muscle; the influences of contraction mode (concentric vs eccentric) on tendon growth haven’t been directly investigated. In addition, no research has ever investigated if timed nutrient timing with whey protein combined with FIRE can enhance tendon size.

What does the evidence tell us?

In order to answer these questions, a recent study investigated whether whey protein combined with prolonged eccentric only FIRE training demonstrated a superior means in promoting skeletal muscle and tendon size compared to a concentric only and placebo intervention. This study investigated the effect of 12 weeks of either maximal eccentric or concentric FIRE combined with either a high-leucine whey protein hydrolysate + carbohydrate supplement or isoenergetic (same # of calories) carbohydrate only placebo, on quadriceps muscle and patellar tendon size [4].

Main findings

  • The training-induced hypertrophy of both tendon and muscle were further enhanced with a high-leucine whey protein hydrolysate supplement. A novel finding was that patellar tendon size can be increased with FIRE combined with whey protein hydrolysate supplementation. There was no further enhancement in muscle or tendon size from the placebo (carbohydrate only) condition.
  • These effects were observed to be independent of contraction (eccentric vs concentric) modality. It’s suggested that there is no benefit in utilizing eccentric only contractions when trying to enhance muscle size. This means that you wouldn’t get bigger biceps by just lowering the bar (eccentric contraction) and not raising it (concentric contraction) while doing biceps curls during your training cycle.


Observations from this research suggest that FIRE enhanced tendon and muscle size following 12 weeks of training. Muscle and tendon size was further enhanced by high-leucine whey protein hydrolysate supplementation compared to isoenergetic (same calories) placebo (carbohydrate only) supplementation. There was no advantage of performing a certain contraction mode (concentric vs eccentric) when trying to enhance muscle and tendon size.

Implications of this research

  • It’s clear that muscle size can be enhanced no matter if you perform eccentric only or concentric only actions.
  • In support of previous research; nutrient timing with high-leucine whey protein hydrolysate enhances muscle hypertrophy.
  • It seems that timed protein ingestion as utilized in the metabolic window is a strong determinant for inducing muscle hypertrophy.
  • The synergistic effect of combining high-leucine whey protein hydrolysate and FIRE on tendon hypertrophy could have important clinical implications since enhancing tendon size and strength may lower the mechanical stress on the tendon during exercise and potentially assist in tendon rehabilitation following injury.

FIRE training and nutrient timing with whey protein are a big part of the Metabolic Precision program.


1. Atherton, P.J. and K. Smith, Muscle protein synthesis in response to nutrition and exercise. J Physiol, 2012. 590(Pt 5): p. 1049-57.

2. Hulmi, J.J., C.M. Lockwood, and J.R. Stout, Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein. Nutr Metab (Lond), 2010. 7: p. 51.

3. Seynnes, O.R., et al., Training-induced changes in structural and mechanical properties of the patellar tendon are related to muscle hypertrophy but not to strength gains. J Appl Physiol (1985), 2009. 107(2): p. 523-30.

4. Farup, J., et al., Whey protein hydrolysate augments tendon and muscle hypertrophy independent of resistance exercise contraction mode. Scand J Med Sci Sports, 2014. 24(5): p. 788-98.

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