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| Pretty much the study set-up, albeit with a Scott bench to support the arm and much more weight. |
Well, I did. After reading the complete study and taking a look at previous research, however, I have admit that the scientists' conclusion that "BFR attenuated HI-ECC-induced muscle damage and there was no increase in cardiovascular responses" is warranted - even if I'd say that the last word on the real-world effect on gains has not been spoken, yet.
You can learn more about BFR and Hypoxia Training at the SuppVersity
BFR, Cortisol & GH Responses
BFR - Where were we in 2013?
Cardio with BFR = Win?
BFR for Injured Athletes
Strength ⇧ | Size ⇩ w/ BFR
1st Study Shows Extra-Gains
"The arms were randomly chosen to perform the exercise in one of the two conditions: without or with BFR (HI-ECC and HI-ECC+BFR conditions, respectively), and counterbalanced such that each condition included both dominant and non-dominant arms. For the experimental session, participants performed three sets of 10 repetitions of HI-ECC or HIECC+BFR (130% of 1RM) of unilateral elbow extension in the Scott bench using free weights (dumbbells)" (Curty 2017).The rest between sets was restricted to one minute, the cadence of eccentric action was 3 s between the initial position (elbow flexed) and full extension of the elbow, while the concentric action was performed passively by the staffs returning the dumbbell at the top of the movement so that only the eccentric action was performed. The experimental session with the contralateral arm was performed at the same day, after 30 min of rest.
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| In contrast to its effects on endurance capacity, post-exercise blood flow restriction as it was practiced in a recent study by Madarame et al. does not enhance the longitudinal increase in strength or size (Madarame 2017). |
What I can tell you, though, is that Haruhiko Madarame and colleagues have shown just recently that postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise. That's in contrast to the previously discussed results showing benefits on endurance performance with post-exercise cuffing, by the way.
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| Figure 1: Indirect markers of muscle damage. Comparison of the HI-ECC versus HIECC+BFR conditions at different moments (pre-exercise, post-0 h, post-24h and post- 48 h) to muscle soreness (a), ROM (b) and CIR (c). Data are represented as D mean +/- SEM. ROM, range of motion; CIR, upper arm circumference (Curty 2017). |
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| Figure 2: A similar study by Nosaka et al. (1996) shows a very different time-course of muscle swelling and thus biceps circumference - the significant and, in this context, experimentally relevant difference is the training status of the subjects - trained in the study at hand, untrained in Nosaka's. |
So what? Well, there is a significant difference in the study design: the subjects in the study at hand were not just accustomed to resistance training (2-3 workouts per week). It is well-proven that muscle damage is reduced already after one bout of resistance training and keeps declining with one's training status. Against that background, I would subscribe to the scientists' conclusion.
The result also seems to be in line with the previous observation that BFR does not increase the muscle damage after low-intensity eccentric contractions with blood flow restriction (Thiebaud 2014) - the least we can say is thus: using cuffs during intense (eccentric) training does not, as one would expect, increase the exercise-induced muscle damage; in fact, it is even likely that it exerts protective effects - even if the accumulation of metabolic products (Pearson 2015) makes it harder to endure, because it increases the perceived pain.
Speaking of an accumulation of metabolic products, the latter are also one of the factors of which the authors speculate that they could explain the reduced muscle damage in HI-ECC+BFR condition: (1) the increase in [Ca2+], (2) the accumulation of intramuscular metabolites, (3) an increase in fibre recruitment, and (4) a potential reduction of neutrophil infiltration and thus inflammation | Comment on Facebook!
- Curty, et al. "Blood flow restriction attenuates eccentric exercise-induced muscle damage without perceptual and cardiovascular overload." Clin Physiol Funct Imaging (2017).
- Damas, Felipe, et al. "Resistance training‐induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage." The Journal of physiology 594.18 (2016): 5209-5222.
- Madarame, et al. "Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise." Clin Physiol Funct Imaging (2017). Ahead of print.
- Nosaka, Kazunori, and Priscilla M. Clarkson. "Changes in indicators of inflammation after eccentric exercise of the elbow flexors." Medicine and science in sports and exercise 28.8 (1996): 953-961.
- Pearson, Stephen John, and Syed Robiul Hussain. "A review on the mechanisms of blood-flow restriction resistance training-induced muscle hypertrophy." Sports medicine 45.2 (2015): 187-200.