Monday, February 3, 2014

More BFR Lovin': Can the Cortisol + GH Response to Blood Flow Restriction Explain the Strength Gains We're Seeing?

"Cuffed up and ready to grow"? Yes, but STRONGER, but not necessarily bigger - that's at least what the latest research seems to suggest. Research that's bringing us back to the influence of exercise induced changes in growth hormone, cortisol and co, we all love so much ;-)
If you've read my article "Strength ⇧ | Size ⇩ - That's the Result of 7 Weeks With Three Additional Sets of Blood Flow Restricted High Rep + Low Intensity Squats & Bench Presses in Well-Trained Athletes" (read more), you will be aware that the previously reported strength increases in response to the addition of 3 sets of blood flow restricted high rep, low intensity work are dearly bought.

The price you'll have to pay for theses strength increases is a reduced increase in muscle size that's particularly pronounced for the pectoralis major (the large chest muscle), where doing those three extra-sets leads - irrespective of whether you're "all cuffed up" or not - to a reduction(!) in muscle size (as measured by chest circumference).

Obviously we cannot explain the catabolic effects,....

... by taking a look at the results of another recently published study on blood flow restriction. What the results Eonho Kim et al. present in their most recent paper in the Journal of Sports Science and Medicine could tell us, though, is whether the positive effects on strength development are mediated by BFR-induced changes in the expression of "anabolic" hormones.
Important note: The previously reported negative effects on muscle size are negative effects that ar brought about by the "pump sets" at the end of the workout - they are not negative effects of BFR.
As the scientists from the University of Oklahoma point out, the purpose of their study was to determine whether there was an acute hormone response to exercise differed between low intensity blood flow restricted resistance exercise and traditional high-intensity resistance exercise in college-aged women.

Suggested: "Anabolic Workouts Revisited: Testosterone, GH, Prolac- tin & Co - Effects of Workout Type, Volume & Density" | more
As a seasoned SuppVersity veteran you'll know that "acute" is not "chronic" and that these acute differences in "hormone response" are difficult to place. Based on the results of the only currently available study with useful data on the relation between the expression of "anabolic" and purportedly "catabolic" hormones on the one hand, and the increase in muscle size and strength in response to classic 12-week resistance training program (see Table 1), we should watch out for increases in cortisol, only (!).

The allegedly catabolic stress hormone, of which most people forget that it is eventually a glucocorticoid and allows you to train without having to have a glucose infusion at hand, is the only  hormone with significant (p = 0.03) positive correlations (r = 0.29) with the strength gains of the 56 young men who participated in the 2012 study by West & Phllips (West. 2012).

What about the cuffed up ladies in the study at hand, then?

If we assume that (a) the acute post-workout increase in cortisol is actually an indicator of chronic strength increases and (b) that this is the same for men and women, we should see higher glucocorticoid levels in the 13 healthy women (aged 18-25 yrs), who participated in the Kim study, when they trained with cuffs, then we do, when they train without cuffs.
Figure 1: Relative changes (pre vs. post) in lactate, growth hormone, hematocrit and cortisol in response to leg presses and leg extensions with (1x30, 2x15 @20% 1RM) and without (3x10 @80% 1RM) blood flow restriction (Kim. 2014)
Well, what should I say? The increases in cortisol, we predicted based on our analysis of the West study are there! The cortisol expression differed significantly between the two training conditions, in the course of which the 13 ladies performed ...
  • Don't forget to read more about the "anti-size" effects of BFR" | more
    5 minutes of warm up on a cycle ergometer, plus
  • high intensity leg presses and extensions
    for 3x 10 @ 80% 1RM, or
  • BFR leg presses + extension
    for 1x30, 2x15 @ 20% 1RM with
  • 1 minute rest between sets and exercises.
During the BFR condition the participants wore an elastic cuffs (50 mm width) on the proximal thighs. The initial cuff pressure was set between 40 and 60 mm Hg, then inflated to 120 mm Hg for 30 seconds then released. The cuff pressure was increased by 20 mm Hg incrementally until the target pressure of 200 Hg was reached as described by previously published studies (Abe et al., 2006; Yasuda et al., 2006). Since the cuff was deflated and removed after the completion of the two lower body exercises, the total time of vascular restriction was "only" about 10 minutes.
Block Periodization - Training revolution or simple trick to break out of the comfort zone? If it's the latter, it will almost certainly produce increased cortisol levels before you will see any increase in performance.
Bottom line: While the study at hand does not answer whether the increases in cortisol are corollary or causatively involved in the performance increases, the results Kim et al. present in their latest paper are 100% in line with my argumentation in my previous article "All About Cortisol, Fat Loss, Body Composition and the Efficacy & Safety of 7-Keto & Co" (read more).

The cortisol spike after a workout is there for a reason; and even though it's probably not causally involved in the performance gains in this and the performance and size gains in the West study, it is at least a good indicator that you're breaking out of the comfort zone, where adapational processes would be unnecessary.

Futthermore, the increase in glucocorticoid receptors on immune cells in response to heavy exercise (Fragala. 2011) would support the notion that the anti-inflammatory effects of cortisol, the fitness freaks often tend to overlook are critically involved in the pro-anabolic immune response to exercise. In conjunction with systemic and, more importantly, local changes in GH (in the study at hand BFR lead to a significant GH increase), IGF-1 and its splice variants, an adequate glucocorticoid response could even be causally involved in the training-induced performance gains.
  • Abe, Takashi, Charles F. Kearns, and Yoshiaki Sato. "Muscle size and strength are increased following walk training with restricted venous blood flow from the leg muscle, Kaatsu-walk training." Journal of Applied Physiology 100.5 (2006): 1460-1466. 
  • Fragala, Maren S., et al. "Glucocorticoid receptor expression on human B cells in response to acute heavy resistance exercise." Neuroimmunomodulation 18.3 (2011): 156-164. 
  • Kim, Eonho, et al. "Hormone Responses to an Acute Bout of Low Intensity Blood Flow Restricted Resistance Exercise in College-Aged Females." Journal of Sports Science and Medicine 12 (2013): 91-96.
  • West, Daniel WD, and Stuart M. Phillips. "Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training." European journal of applied physiology 112.7 (2012): 2693-2702.
  • Yasuda, T., et al. "Electromyographic responses of arm and chest muscle during bench press exercise with and without KAATSU." International Journal of KAATSU Training Research 2.1 (2006): 15-18.