Sunday, January 21, 2018

Replacing CHO W/ Protein Won't Impair Glycogen Resyn-thesis | Plus: RT+HIIT & Satellite Cells; BFR & Recovery

If that's what your PWO meal looks like, you're doing it right.
I am sorry it took me so long to complete the follow-up to last week's article about the latest "recovery science" - my real job took a toll... in fact, I still have to hurry and will, therefore, skip a lengthy introduction that won't add to the educative value of today's article, anyway... the only thing I would like to say in advance is: I am going to do my best to decrease the interval between SuppVersity articles again.

Maybe it will comfort you to hear that there are five studies in today's research update - five studies that are not all directly related to exercise recovery and yet still practically relevant for your training and nutrition planning (see "What's the practical implication?" at the end of each bullet-point if you want to read only the gist(s)).
Learn more about building muscle and strength at www.suppversity.com

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Here are the topics of installment #2 of the recovery science research update January 2016 (click here to read the previous one):
  • Blood flow restriction late in recovery after heavy resistance exercise hampers muscle recuperation (Bunevicius 2018) -- In view of the results of the latest study by scientists from the Lithuanian Sports University, you seem to be ill-advised to use BFR training and heavy training in one and the same workout... at least not alternatingly with BFR during inter-set rest periods as the results of the previously discussed 2015 study by Taylor may suggest.

    Due to methodological differences, the study at hand does not really contradict the results of the post-set BFR study by Taylor et al (learn more). What the study at hand does do, however, is to make us question the use of "intermittent BFR", as you may want to call it, at a point in your workout where you haven't yet completed all the high-intensity sets.
    In their RCT the Lithuanian scientists investigated the effects of two bouts of one-leg dynamic plantar flexion exercise to failure with the load equivalent to 75% of maximum with and without high occlusion pressure (200mmHg) being applied for 15 minutes towards the end of a 20 minute period of passive recovery after the first and before the second bout.

    The subjects, amateur male middle- and long-distance runners, were randomly assigned into two experimental groups. In addition to the "passive rest"-only group, there was a third group of subjects who rested only 5 minutes before the retest.
    As the authors' analysis of the data shows, the work capacity in the BFR group was significantly compromised in both groups, albeit to a different degree with a reduction of 10.5 ± 3.1%, BFR had a significantly more pronounced effect (vs. 9.3 ± 2.2% with 120 mmHg | p < 0.05) with 200 mmHg occlusion pressure.

    What's the practical implication? In view of the potential negative impact of the reduced workload, it is possible, but by no means proven, that the adaptational response to the workout may suffer. Against that background, the more important message to remember may be the difference between the control groups, where the work capacity was restored after 20 min (− 3.9 ± 3.2%, p > 0.05) but not after 5-min recovery (− 20.0 ± 1.8%, p < 0.05). If you want to train at maximal workloads (and that appears to be one of the few things that are really affecting muscle gains), longer rest times seem to be beneficial.
Blood pressure (mmHg) of subjects in diff. body positions (Sieljacks '18).
Speaking of BFR, ... another recent study (Sieljacks 2018) shows that your individual body position during an exercise influences the arterial occlusion pressure. This has important implications for both scientists and practitioners who want to standardize the pressure during blood flow restricted exercise.

As you can see in Figure to the left, you will have to make up for the position (=seating) dependent increase in blood pressure. The relative difference between a wide and narrow cuff, on the other hand, is virtually identical in both positions.
  • Satellite cell activity is not impaired by a combination of resistance and HIIT training (Pugh 2018) -- Satellite cells are "muscles to be", I've written about them and their role in both skeletal muscle growth and repair in various contexts, before.

    Figure 1: Participant flow diagram. The dashed box indicates the participants who withdrew from the study (Pugh 2018)
    With Jamie K. Pugh, Steve H. Faulkner, Mark C. Turner, and Myra A. Nimmo's latest paper in the European Journal of Applied Physiology (read it for free) focused on the individual response of these cells in middle-aged, sedentary, overweight/obese individuals - a segment of the society that is particularly prone to develop metabolic disease and sarcopenia, i.e. the loss of skeletal muscle mass and strength as a result of ageing.

    As previously hinted at, satellite cells will replace damaged myonuclei in your muscle and thus help maintain the structural integrity and function of your biceps, triceps, abs and all the other muscles in your body.

    In the study at hand, the researchers did now investigate if the proven 'muscle maintaining' effects of resistance training (here in form of 8 × 8 leg extensions at 70% 1RM), would persist, when the subjects did an additional, metabolically demanding and thus fitness improving HIIT (10 × 1 min at 90% HRmax on a cycle ergometer) protocol right after the leg extensions.
    Figure 2: Satellite cell content (Pax7+) before and 96 h after a single bout of resistance exercise (RE) versus resistance exercise and high-intensity interval training (RE + HIIT). a–d Representative images of muscle fiber type-specific Pax7 immunofluorescent staining. Merged images of a Pax7/DAPI/laminin/MHC I (green)/MHC II (red), and b Pax7/DAPI/laminin (red) are provided, with single channel views of c DAPI (blue) and d Pax7 (green). Arrow denotes a Pax7+ cell. Scale bar 20 ┬Ám. Pax7+ cells per e type I and f type II muscle fiber before and 96 h after resistance exercise in both trials. Symbols above lines denote differences when a main effect was observed. *P < 0.05 vs. Pre. Data presented as mean ± SEM (Pugh 2018).
    Muscle biopsies were collected from the vastus lateralis before and 96 h after the RE component to determine muscle fiber type-specific total (Pax7+ cells) and active (MyoD+ cells) satellite cell number using immunofluorescence microscopy; and here's what they found:
    "Type-I-specific Pax7+ (P = 0.001) cell number increased after both exercise trials. Type-I-specific MyoD+ (P = 0.001) cell number increased after RE only. However, an elevated baseline value in RE + HIIT compared to RE (P = 0.046) was observed, with no differences between exercise trials at 96 h (P = 0.21). Type-II-specific Pax7+ and MyoD+ cell number remained unchanged after both exercise trials (all P ≥ 0.13)" (Pugh 2018).
    In other words, at least acutely there's no evidence that a single HIIT session after 'weights' will interfere with the anti-sarcopenic satellite cell response to resistance training.

    Hitting it After Weights - There are downside, but Systemically Impaired Strength & Size Gains are a Myth | more
    What's the practical implication? With conflicting results from previous research showing conflicting results, it should be clear that any single study won't get concurrent training off the hook. There's still the possibility of differences in long-term adaptation, but if you remember the last article in which I touched on the pros and cons of post-RT HIIT, you will also remember that its detrimental effects on protein synthesis and co. are probably overrated and the health-, fitness-, and body-composition-benefits of adding any form of endurance training to your regimen - ideally, obviously, on separate days - cannot be ignored.
Food for thought: The availability of water associated with glycogen during dehydration: a reservoir or raindrop? (King 2018) -- Roderick F. G. J. King et al. authored an interesting paper in which they report the results of an experiment designed to find out, whether glycogen-associated water is a protected entity not subject to normal osmotic homeostasis. The answer to the initially raised question is: It's a raindrop. In their paper, which is likewise available as open access, King et al. show that "glycogen-associated water does not appear to be a separate reservoir and is not able to uniquely replete water loss during dehydration.

Practically speaking this result may be of specific importance for "fat-fuelled" athletes whose glycogen stores are - especially at the beginning of their fat-laden journey to full ketosis often depleted and the water content of the musculature reduced (for these athletes it's obviously good news). Moreover, the results of the study at hand put a question mark behind the hypothesis that protected water could provide rehydration when hypohydrated, especially when water loss has occurred through sweat loss as it has been suggested by Maughan et al. (2007)... since the data King et al. present in the February issue of the European Journal of Applied Physiology is based on in-vitro data, only, it would be, as the scientists write "worthwhile to consider approaches in vivo where accurate and precise osmotic pressure changes simultaneously with changes in cell glycogen and water were made", but as King et al. rightly point out: "this would be difficult in humans" (King 2018).
  • Partly replacing carbs w/ dairy protein does not significantly effect post-workout glycogen recovery (Cogan 2018) -- Since we have already been talking about glycogen, it may be worth to end this research summary with a study addressing the recovery of glycogen stores post-workout.

    As a SuppVersity reader you will remember that plain milk can easily compete with special sports drinks like Gatorade, when it comes to its ability to restore muscular glycogen levels after a workout. With milk being a mix of both carbohydrates (which are obviously important to max out the glycogen recovery) and protein it was thus not unreasonable of Cogan et al. to assume that combining both, i.e. carbohydrate (CHO) and dairy protein in form of either sodium caseinate protein (CHO–C) or a sodium caseinate protein hydrolysate (CHO–H) could have a beneficial effect the post-workout glycogen recovery of trained male cyclists [n = 11, mean ± SEM age 28.8 ± 2.3 years; body mass 75.0 ±2.3 kg; VO2peak 61.3 ±1.6 ml kg/min].
    Figure 2: Glycogen concentrations and rates of glycogen resynthesis following 2 h of aerobic exercise (~ 70%VO2peak) after 4 h of recovery. a Mean (±SEM) muscle glycogen concentration at baseline, and +0 and + 4 h or recovery following the ingestion of carbohydrate (CHO); or isoenergetic drinks containing CHO and intact sodium caseinate (CHO–C); or CHO and hydrolysed sodium caseinate (CHO–H | Cogan 2018).
    And, in fact, in view of the fact that the "CHO+"-treatments contained lower amounts of CHO (1.04 and 0.16 g kg/BM) than the CHO-only treatment (1.2 g kg/BM) there must have been a small improvement in the relative efficacy (i.e. amount ingested per increase in glycogen content) of the carbs in the recovery drinks the subjects were served +0 and +2h after having cycled for 2h at ~ 70% VO2peak.
    Figure 3: Plasma amino acid concentrations during 4-h recovery. Mean (±SEM) for (a) total, (b) EAA, and (c) BCAA plasma amino acids during 4-h recovery (n=10 | Cogan 2018)
    In addition, the combination of carbohydrates and protein produced a significant hyperaminoacedemic state (=elevated total, EAA and BCAA levels in the blood | see Figure 3) that went hand in hand with potentially gain-relevant increases in regulators of post-workout protein synthesis (the actual fractional synthesis rates weren't measured, by the way).

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    What's the practical implication? At first sight, the study seems to fail to add any practical tools to your evidence-based training toolbox, but if you come to think about it, the message that "protein co-ingestion, compared to CHO alone, during recovery did not augment glycogen resynthesis" (Cogan 2018) is not disappointing, but rather in support of replacing some of your PWO carbs with dairy proteins. Why's that? Well, you won't miss out on glycogen recovery and will, at the same time, improve your hypertrophy potential due to the significant increases in phospho-mTOR Ser2448 and 4EBP1 Thr37/46 versus CHO only.

    In this context, it is probably also worth considering that even if (a) both forms of casein used in the study at hand are fast-digesting (only micellar casein clumps and is thus slow-digesting), the hydrolyzed version of the dairy protein produced the greatest increase in markers of post-workout anabolism (and slightly higher insulin levels)  the casein hydrolysate was both
That's it for today, and I hope that I will have more time for regular updates in the weeks to come - sorry for the recent delays and reduced number of posts on both, this website, i.e. suppversity.com, and the Facebook news-page | Comment on Facebook!
References: 
  • Bunevicius, Kestutis, et al. "Blood flow restriction late in recovery after heavy resistance exercise hampers muscle recuperation." European journal of applied physiology 118.2 (2018): 313-320.
  • Cogan, Karl E., et al. "Co-ingestion of protein or a protein hydrolysate with carbohydrate enhances anabolic signaling, but not glycogen resynthesis, following recovery from prolonged aerobic exercise in trained cyclists." European journal of applied physiology (2017): 1-11.
  • King, Roderick FGJ, Ben Jones, and John P. O’Hara. "The availability of water associated with glycogen during dehydration: a reservoir or raindrop?." European journal of applied physiology 118.2 (2018): 283-290.
  • Maughan, Ronald J., Susan M. Shirreffs, and John B. Leiper. "Errors in the estimation of hydration status from changes in body mass." Journal of sports sciences 25.7 (2007): 797-804.
  • Pugh, Jamie K., et al. "Satellite cell response to concurrent resistance exercise and high-intensity interval training in sedentary, overweight/obese, middle-aged individuals." European journal of applied physiology 118.2 (2018): 225-238.
  • Sieljacks, Peter, et al. "Body position influences arterial occlusion pressure: implications for the standardization of pressure during blood flow restricted exercise." European journal of applied physiology 118.2 (2018): 303-312.