|Concentration curls are one of the few exercises, where eccentrics make sense. They are safe and you can even do them if you don't have a training partner.|
Quite an intriguing conclusion that puts yet another huge questionmark behind the usefulness of the three dozen of studies that measure exclusively (acute) protein synthesis to assess the efficacy of certain exercise and/or supplementation regimen.
Before we get caught up in discussing the implications of the study at hand (as we are going to see later, we would be jumping to conclusions, anyways), it would yet be wise to take a closer look at the data that's at the heart of the previously cited conclusion.
Rahbek and her colleagues from the University of Aarhus and the University of Copenhagen set out to confirm the following hypothesis (Rahbek. 2014):
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- The effects would be amplified if the subjects consume whey protein hydrolysate and carbohydrates after the workout compared to carbohydrates, alone.
- Compared to the concentric training, the eccentric training would provide a stronger hypertrophy response and a more sustained increase in proteins involved in the mTOR protein synthetic cascade.
"All participants per formed eccentric work (ecc) with one leg and concentric work (cOnc) with the other leg. eccentric exercise was randomly ascribed to either the dominant (preferred kick ing leg) or the nondominant leg to exclude any potential pre-training differences between the legs." (Rahbek. 2014)In addition, the effects of a WPH +cHO supplementation versus isocaloric cHO supplementation were investigated in the single bout trial and the training period. The participants were randomly divided into one of the two supplement groups and supplements were provided in a double blinded fashion. this within-participant design with regard to contrac tion mode was used to minimize the potential differences in the training response that are inherent with group designs because of differences in initial training, nutritional and hormonal status. Accordingly, the following four inter ventions were compared: (I) eccentric training with WPH + CHO; (II) eccentric training with CHO only; (III) conencentric training with WPH + CHO, and; (IV) concentric training with CHO.
Injury warning - eccentric squats are not save ;-) Aside from the ease of execution and the high standardization the mere fact that you can do safely do eccentric leg extensions was probably the main reason for the Danish researchers to pick the leg extension as their exercise of choice. I can only warn you, not to do squats or a similar multi-joint full-body exercise "eccentrically" - with or without spotter!Throughout the study period, the participants were instructed to maintain their normal habitual physical activity level and dietary intake. Three days prior to the start of the study, the participants were asked to refrain from physical exercise. One basal muscle biopsy was then sampled from a randomly chosen leg. The biopsy was repeated twice: Three days after the 7-day habituation phase, and 3-6 days after the last training session 12 weeks later.
"Each participant completed 2–3 exercise sessions per week over a 12-week period to a total of 33 training sessions. All exercise sessions were initiated with 5 min light bicycling warm-up. Eccentric load was aimed at 120 % relative to concentric loading, with a training supervisor assisting to allow isolated exercise modality of the two legs. the load difference is parallel to the approximate strength difference between slow ecc[entric] and con[centric] contractions during isokinetic strength testing." (Rahbek. 2014)Unfortunately, the resistance training program consisted of isotonic knee extensions, only (understandable from a science perspective, but disappointing for all of us who would have preferred a more realistic training scenario). The latter were performed with the following set × repetitions:
|Figure 1: Sustained elevations in anabolic signalling were observed only in the eccentric training group.|
- 6 × 10– 15 rM (sessions 1–4),
- 8 × 10–15 rM (sessions 5–10),
- 10 × 10–15 rM (sessions 11–20),
- 12 × 6–10 rM (sessions 21–28), and
- 8 × 6–10 rM (sessions 29–33)
|Figure 2: Changes (%) in quadriceps CSA over the 12-week training period (Rahbek. 2014)|
- Aagaard, Per, et al. "Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training." Journal of Applied Physiology 89.6 (2000): 2249-2257.
- Rahbek et al. "Divergent resistance exercise contraction mode and dietary supplementation type on anabolic signalling." Amino Acids (2014). Ahead of print.