Showing posts with label BFR. Show all posts
Showing posts with label BFR. Show all posts
Wednesday, November 4, 2015
Blood Flow Restriction in Athletes: Did We Get it All Wrong? Must BFR-Cuffs be Worn After, not During Each Set?
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| If that's you. It's well possible that you've done it all wrong. Wearing the cuffs after the set may be the way to go! |
In their study, the researchers from the Loughborough University in Leicestershire had their subjects, 28 healthy trained males who were cycling 120 ± 66 km per week, all cuffed up after each set of a standardized sprint training. That's very dufferent from trying to sprint with cuffs on your legs (and usually reduced intensity) and appears to be - that's at least what the study results suggest - a potential game-changer.
You can learn more about BFR and Hypoxia Training at the waredownloadsoft
BFR, Cortisol & GH Responses
BFR - Where are we now?
Hypoxia + HIIT = Win?
BFR for Injured Athletes
Strength ⇧ | Size ⇩ w/ BFR
Training & Living in Hypoxia
- In Study 1, a between groups design determined whether 4 weeks (2 d/wk) of SIT (repeated 30 s maximal sprint cycling) combined with post-exercise blood flow restriction (BFR) enhanced maximal oxygen uptake (VO2max) and 15km cycling time trial performance (15km-TT) compared to SIT alone (CON) in trained individuals.
- In Study 2, using a repeated measures design, participants performed an acute bout of either BFR or CON. Muscle biopsies were taken before and after exercise to examine the activation of signalling pathways regulating angiogenesis and mitochondrial biogenesis.
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| Figure 1: Pre- to post-changes in VO2max (absolute, top-right), relative (top-left), MAP (bottom-left), 15k time trial (bottom-right) | I marked the individuals who saw positive and negative effects for you, the # on the buttons indicate the number of subjects who benefited (green) or saw no / detrimental effects (orange | original data from Taylor. 2015). |
So, does the increase in VO2 have anything to do with my gainz? Directly? No. But if there's an effect on hypertrophy it would - just as the effect on VO2 found in the study at hand - depend on increases in the stress response. Now, the more recent studies have shown that the necessary reduction in weight lifted when you do it with cuffs makes it practically useless for athletes. So, in conjunction with the study at hand, it's only logical to ASSUME that using the hypoxic stress after a set COULD provide an ADDITIVE stimulus (normal BFR training takes away from the regular stimulus, because it will.force athletes to refuce the weights and cannot fully compensate for that | see the results of this study.
The small advantage in the 15k time trial, on the other hand, did not reach statistical significance. That's "bad news", but the trend indicates that this might change with long(er) term studies. |
| Figure 2: Changes (%) in physiological and performance variables before and after CON and BFR training interventions (Taylor. 2015). |
Bottom line: While it is possible that the differences the scientists observed were triggered by BFR induced extra-stress (namely hypoxia, thus increases in Hypoxia-inducible factor 1-alpha), we will need additional (longer-term) studies to prove practically relevant improvements in time-trial performance and identify a definitive mechanism.
With that being said, the results - although not fully convincing, yet - are quite exciting. After all, they really suggest that instead of training with cuffs, athletes who want to benefit from the additional low oxygen stress would have to copy the protocol of the study at hand and thus apply lower limb blood flow restriction within 15s of each sprint... or after each set of leg curls or squats? Well, that's a question we cannot answer based on the study at hand, but it would certainly be interesting to test what would happen if you applied the cuffs right after a set of biceps curls. Well, as you can see, there's still a lot of research to be done and as you know, the waredownloadsoft is going to be where you can learn about the results first ;-) | Comment on Facebook!
References: |
| The benefits of blood flow restriction in healthy athletes may be less pronounced than the advocates would have it. If reversing the order of exercise and applying the cuff can solve that, this would be awesome! |
- Lindholm & Rundqist, et al. "Skeletal muscle HIF-1 and exercise." Experimental Physiology (2015): Accepted Article.
- Taylor, et al. "Acute and chronic effect of sprint interval training combined with post-exercise blood flow restriction in trained individuals." Experimental Physiology (2015): Accepted Article.
BFR Preconditioning Not Better Than Placebo? Long Rest Periods For Sustained Testosterone Increase? Train One Leg, Grow Both? - Resistance Training Update October '14
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| Single-legged leg presses that make both legs stronger are only one of many topics, today. |
Ah, and since there was some space left in the bottom line, we will acknowledge that AM vs. PM training have identical effects on power, force and hormonal response in young men and pretend to be surprised that a three-set upper-body workout is much more energetically demanding than its one-set analog. All in all, a very balanced update on the latest resistance training research, I'd say.
Read more about exercise-related studies at the waredownloadsoft
Tri- or Multi-Set Training for Body Recomp.?
Aug '15 Ex.Res. Upd.: Nitrate, Glycogen, and ...
Pre-Exhaustion Exhausts Your Growth Potential
Full ROM ➯ Full Gains - Form Counts!
Body Pump, Cardio & Exercise Expenditure
Study Indicates Cut the Volume Make the Gains!
Tri- or Multi-Set Training for Body Recomp.?
Aug '15 Ex.Res. Upd.: Nitrate, Glycogen, and ...
Pre-Exhaustion Exhausts Your Growth Potential
Full ROM ➯ Full Gains - Form Counts!
Body Pump, Cardio & Exercise Expenditure
Study Indicates Cut the Volume Make the Gains!
- Long rest periods prolong testosterone response to bench press exercise -- From various previous waredownloadsoft articles you know that resistance training triggers an acute increase in testosterone. That this increase may depend on the rest between sets, though, is news. News from a recent article in the Journal of Strength and Conditioning Research.
The purpose of the study was to examine the influence of rest period duration (1 vs. 3-minute between sets) on acute hormone responses to a high intensity and equal volume bench press workout (5x3 sets at 85% of the 1RM, to be specific).
To this ends, Scudese et al. (2015) recruited ten resistance trained men (25.2 +/- 5.6 years; 78.2 +/- 5.7 kg; 176.7 +/- 5.4 cm; bench press relative strength: 1.3 +/- 0.1 kg/kg of body mass) and had them perform two bench press workouts separated by one week. Each workout consisted of 5 sets of 3 repetitions performed at 85% of 1-repetition maximum, with either 1 or 3-minute rest between sets. The rates of perceived exertion and serum levels of growth hormone (GH), cortisol, free and total testosterone were sampled at three different timepoints right (PRE), right after (T0) before, 15 (T15) and 30 (T30) minutes after. The results were as follows:
Figure 1: Mean (left) and individual (right) free testosterone levels before and after performing bench presses with 1 min or 3 min rest (Scudese. 2015). - For total testosterone, both rest lengths enhanced all post-exercise verifications (T0, T15 and T30) compared to PRE, with 1-minute showing decreases on T15 and T30 compared to T0.
- For free testosterone, both 1 and 3-minute rest protocols triggered augmentations on distinct post-exercise moments (T0 and T15 for 1-minute; T15 and T30 for 3-minute) compared to PRE.
- Since the the cortisol values did not change throughout any post-exercise verification for either rests, the total testosterone/cortisol ratio was significantly elevated for both rests in all post-exercise moments compared to PRE.
The growth hormone values did not change for both rest lengths.
What's of significantly greater importance for the interpretation of the study results is yet a study by West et al. (2012) who observed that the testosterone response (both free and total) to resistance training is not associated with either strength or size gains. So what? It is very likely that the results of the study at hand are of zero practical relevance for your gains (strength- and sizewise, as West's study indicates). - Blood flow restriction before strength training? It works - just as well as placebo! -- You will probably remember my recent article about the benefits of using blood flow restricting cuffs before a sprint workout, right (click here if not)? With the publication of the results of Moacir et al.'s (2015) latest study, we do now know that similar benefits will be seen with subsequent resistance training, too.
"Thirteen men participated in a randomized crossover design that involved 3 separate sessions (ischemic preconditioning, placebo and control). A 12-RM load for the leg extension exercise was assessed through test and retest sessions prior to the first experimental session. The IPC session consisted of 4 cycles of 5 minutes occlusion at 220 mmHg of pressure alternated with 5 minutes of reperfusion at 0 mmHg for a total of 40 minutes. The PLACEBO session consisted of 4 cycles of 5 minutes of cuff administration at 20 mmHg of pressure alternated with 5 minutes of pseudo-reperfusion at 0 mmHg for a total of 40 minutes.
The study at hand should make you question the results of the previously discussed study which did not have a placebo group | learn more The occlusion and reperfusion phases were conducted alternately between the thighs, with subjects remaining seated. No ischemic pressure was applied during the control (CON) session and subjects sat passively for 40 minutes. Eight minutes following IPC, PLACEBO or CON, subjects performed three repetition maximum sets of the leg extension (2min rest between sets) with the pre-determined 12-RM load. Four minutes following the third set for each condition, blood lactate was assessed" (Moacir. 2015)
When the researchers analyzed the results, they found that for the first set, the number of repetitions significantly increased for both the IPC (13.08 +/- 2.11; p = 0.0036) and PLACEBO (13.15 +/- 0.88; p = 0.0016) conditions, but not the CON (11.88 +/- 1.07; p > 0.99) condition.
Similarly, the IPC and PLACEBO conditions resulted in significantly greater repetitions versus the CON condition on the 1st set (p=0.015; p=0.007) and 2nd set (p=0.011; p=0.019), but not the 3rd set (p=0.68; p>0.99). No significant difference (p=0.465) was found in the fatigue index and lactate concentration between conditions.
Figure 2: Significant increases in the number of reps (left) were observed for both the placebo and IPC group. The fatique index (right) did not differ between treatments, but the large inter-individual variety in the IPC group clearly suggests that BFR as a means of preconditioning ain't for everyone (Moacir. 2015).
As the researchers point out, their results "indicate that IPC and PLACEBO ischemic preconditioning may have small beneficial effects on repetition performance over a CON condition" (Moacir. 2015). It is thus not completely logical that they suggest "that ischemic pre-conditioning might be practiced gradually to assess tolerance and potential enhancements to exercise performance" (ibid.). What? Oh, you think your clients would notice that their blood flow is not actually impaired and the placebo effect would be lost? Right, now I understand why you should keep using it. Unfortunately that does not exclude that it is still a placebo effect which seems not unlikely in view of the larg(er) inter-individual differences in the IPC vs. any other group. Further studies are necessary... obviously! - Train your right leg, and your left leg will become stronger, too - on leg presses, at least -- What sounds like a joke (or magic) is actually science. Science that is going to be presented in an article in a future edition of the Journal of Strength and Conditioning Research; and more precisely from a study that assessed the cross education of strength and changes in the underlying mechanisms (muscle size, activation, and hormonal response) following a 4-week unilateral resistance training (URT) program.
In said study by Beyer et al. (2015), a group of nine untrained men completed a 4-week URT program on the dominant leg (DOM), while cross education was measured in the non-dominant leg (NON); and were compared to a control group (n=8, CON)."Unilateral isometric force (PKF), leg press (LP) and leg extension (LE) strength, muscle size (via ultrasonography) and activation (via electromyography) of the rectus femoris and vastus lateralis, and the hormonal response (testosterone, growth hormone, insulin, and insulin-like growth factor-1) were tested pre- and post-training" (Beyer. 2015).
In all strength and size related measures, the trained group improved significantly better than CON. Significant group x time effects for PKF, LP, LE, and muscle size were observed only in the dominant leg (DOM), the non-dominant (NON = untrained leg), on the other hand, the scientist observed not just a trend, but rather an actual and statistically significant increase in leg press strength.
Whether that's related to the acute hormonal response to URT, the scientists observed, is more than questionable, after all the strength increase in the non-dominant leg didn't just occur in the absence of "detectable changes in muscle size, activation (EMG), or the acute hormonal response" it did also occur only during leg presses - if it was the result of any of the aforementioned factors one would expect to see at least something like a trend for leg extensions, as well.
Figure 3: Relative leg press and leg extension strength relative to body weight; the values above the post-bars indicate the relative difference between post and pre-test (2015).
Against that background it should also be clear that you must not neglect one leg or arm when you train in the definitely false hope it would grow and the almost certainly false hope it would get stronger as you train your "favorite" limb.
There's more: In view of the fact that the bottom lines to the individuals studies discussed in waredownloadsoft Research Overviews are always provided at the end of the respective item, I have room for mentioning two other interesting results at least briefly.
Firstly, Hatfield et al.'s study of the "Effects of circadian rhythm on power, force, and hormonal response in young men" that indicates that "high force and power exercises utilizing bench press-throws or jump squats may be performed any time of day without detrimental decreases in acute performance" (Hatfield. 2015). And secondly, Mookerjay et al.'s "[c]omparison of energy expenditure during single vs. multiple-set resistance exercise" (Mookerjay. 2015) that yielded a very obvious result which was that the multi-set protocols yield greater metabolic and cardiovascular demands than single set protocols when the number of exercises performed are the same (see Figure 4). In the study 5 upper-body exercises of either 1 or 3 sets per exercise performed in random order the gross and net energy expenditure was determined for the workout + 5 minutes of recovery. You can see the exact data in Figure 4, in case you're interested | Comment on Facebook!
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| Figure 4: Energetic demands of 5x3 vs. 5x1 set upper body workout in men and women. Needless to say that the inter-group difference between 3 vs. 1 sets and the inter-group difference between men and women (not shown) were significant (Mookerjay. 2015). |
References:
- Beyer, et al. "Short-Term Unilateral Resistance Training Results in Cross Education of Strength without Changes in Muscle Size, Activation, or Endocrine Response." Journal of Strength and Conditioning Research (2015): Ahead of print.
- Hatfield, et al. "Effects of circadian rhythm on power, force, and hormonal response in young men." Journal of Strength and Conditioning Research (2015): Ahead of print.
- Moacir, et al. "Ischemic preconditioning and placebo intervention improves resistance exercise performance." Journal of Strength and Conditioning Research (2015): Ahead of print.
- Scudese et al. "Long rest interval promotes durable testosterone responses in high intensity bench press." Journal of Strength and Conditioning Research (2015): Ahead of print.
- 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.
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