Finally, the 1st Blood-Flow Restriction + Classic Training Periodization Study is There and the Gains are Impressive

No, the study did not use a simple rope or band to restrict blood flow. Instead an automated system was used that kept the pressure at stable 100mmHg.
As a SuppVersity reader you know that blood flow restricted training is - at best - as effective as regular resistance training and can thus only be recommended as an adjunct to your regular training (efficacy unproven) or replacement for injured athletes. With a recent thesis by Daniel Cortobius and Niklas Westblad from the Swedish School of Sports and Science, the former use gets scientific backup.

The aim of the bachelor students' study was to investigate how a periodized combination of classic resistance and blood flow restricted resistance exercise (BFRE) compares to regular training when it comes to increase in quadriceps muscle growth and strength.
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Now as great as this sounds, the study has several important weaknesses (few, though, considering the fact that this is undergrad research) due to which it should be considered a "proof of concept", not a "classic + BFR is better than classic alone" study:
  • untrained subjects - 10 males and 10 female (4 dropouts), to be specific, 
  • no dietary standardization (only a 21g vegetable protein shake after workouts),
  • unilateral (=one leg only) resistance training for the legs, only, and 
  • the lack of a non-BFR periodized control group 
Without control group, it should be quite obvious that the magnitude of the results of the strength and ultrasound tests Cortobius & Westblad performed before and after the subjects trained for 10 weeks must be interpreted with utmost caution.
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What did the workouts look like? "After two familiarization sessions subjects performed three sessions per week in leg press and leg extension, except for week 4 and 8 were subjects performed five BFRE training sessions Monday to Friday" (Cortobius. 2016)." During the weeks, the subjects did three sets with 70-75%, 63-67,5% (90% of Monday) and 80-85% of their individual 1RM for 10-12, 10-12 and 5-7 reps on Monday, Wednesday and Friday of weeks 1-3 and 5-7. During the classic training weeks 9-10, they did 2-3 sets of 10-12 reps at 70-75% on Monday, 1 set of 10-12 reps at 63-67,5% (90% of Monday) on Wednesday and 2-3 sets of 5-7 reps at 80-85% on Friday.

During the BFR weeks, subjects exercised every day, but switched back and forth between leg extensions and presses with the former being done on Monday, Wednesday and Friday, and the latter being performed only on Tuesday and Thursday. Both exercises were performed wearing an automated cuff that was set to regulate the pressure at 100mmHg during the workouts. The BFR workouts, itself, consisted of four sets of unilaterally leg press or leg extension the subjects did at a set pace of 60 BPM and 50 BPM for the extensions and press, respectively. As usual, the intensity was reduced for the BFR weeks: 20 % of 1RM in leg extension and 30 % of 1RM in the leg press. With the short rest of thirty seconds after the first set of 30 reps, the 2nd set of 10 reps and the third and fourth set, during which the subjects performed to concentric failure, the BFR workouts were yet still pretty intense. 
This does not refute the authors' conclusion that their findings, namely a significant increase of vastus lateralis muscle thickness by 15,1 % ± 7,6 (p ≤ 0,01 | no difference between genders), as well as leg press 1.RM by 59,1 % ± 27,4 (p ≤ 0,01), and leg extension 1RM by 19,8 % ± 13,1 (p ≤ 0,01), suggest superior effects of periodized BFR + regular training on muscle growth in comparison with most other strength training studies.
Figure 1: Size (left) and strength (right) gains over the 10-week study period / no sign. sex-differences (Cortobius. 2016).
Without a group that trained without cuffs in weeks 4 and 8, too, however, the attribute "superior" is yet practically meaningless. Different subjects, probably different nutrition, different exercises, ... a direct comparison between one study and another is never really valid, even if Cortobius and Westblad are right to point out that that the effects they observed in their study are "much greater than the mean increase of 0.11 % per day reported in a large meta-analysis (Wernbom, Augustsson & ThomeƩ 2007)" (Cortobius. 2016) - without a control group that trained regularly or simply with slightly higher intensity, but similarly high reps to failure daily during weeks 4 and 8, we have no valid benchmark for the results of the study at hand (so let's hope there's a follow up before the authors' master thesis ;-).
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Bottom line: As happy as I am that this study has finally been conducted (you may remember from previous SuppVersity articles on blood flow restriction that I've argued in favor of periodization to use BFR more effectively), there's no way to tell whether BFR + classic training produces greater gains than classic training alone based on the study at hand.

Therefore, we can only hope that a follow-up study with a 1:1 comparison of periodized BFR and unperiodized regular resistance training will be done to finally answer the question, whether the two weeks of training with cuffs actually promoted additional size and/or strength gains (in my dreams, that study would be done with a full body or at least a complete leg workout in trained individuals, obviously ;-) | Comment!
  • Cortobius, Daniel, and Niklas Westblad. "Optimizing strength training for hypertrophy: A periodization of classic resistance training and blood-flow restriction training." (2016).
  • Wernbom, Mathias, Jesper Augustsson, and Roland ThomeĆ©. "The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans." Sports medicine 37.3 (2007): 225-264.
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