Current Opinion in Sports Med 2008

Discussion in 'Hypertrophy Research' started by dkm1987, Jun 25, 2008.

  1. dkm1987

    dkm1987 New Member

    Some brief excerpts from Sports Med 2008; 38 (7): 527-540

    Resistance Exercise Biology

    Manipulation of Resistance Exercise Programme variables Determines the Responses of Cellular and Molecular Signalling Pathways

    Barry A. Spiering

    Abstract

    Recent advances in molecular biology have elucidated some of the mechanisms that regulate skeletal muscle growth. Logically, muscle physiologists have applied these innovations to the study of resistance exercise (RE), as RE represents the most potent natural stimulus for growth in adult skeletal muscle. However, as this molecular-based line of research progresses to investigations in humans, scientists must appreciate the fundamental principles of RE to effectively design such experiments. Therefore, we present herein an updated paradigm of RE biology that integrates fundamental RE principles with the current knowledge of muscle cellular and molecular signalling. RE invokes a sequential cascade consisting of: (i) muscle activation; (ii) signalling events arising from mechanical deformation of muscle fibres, hormones, and immune/inflammatory responses;
    (iii) protein synthesis due to increased transcription and translation; and (iv) muscle fibre hypertrophy. In this paradigm, RE is considered an ‘upstream’ signal that determines specific downstream events. Therefore, manipulation of the acute RE programme variables (i.e. exercise choice, load, volume, rest period lengths, and exercise order) alters the unique ‘fingerprint’ of the RE stimulus and subsequently modifies the downstream cellular and molecular responses.

    Summary 1.1 Muscle activation
    In summary, exercise load, rate of force development, and muscle fatigue affect motor unit recruitment during RE. Motor unit recruitment (and the
    phenotype of the recruited motor units) must be
    carefully considered for responses and adaptations
    to RE because: (i) only those motor units recruited
    will respond and adapt to RE; (ii) heavy loads,
    explosive exercises, and/or significant muscle fatigue is necessary to activate type II motor units;
    (iii) type I and type II muscle fibres display differential signalling responses to muscle contraction;
    (iv) type II muscle fibres have a greater capacity for
    hypertrophy following RE training than type I fibres;[5] and (v) different muscle groups possess varied
    percentages of type I and type II muscle fibres (for
    example, in humans the gastrocnemius is ~60% type
    I muscle fibres and the soleus is ~85% type I muscle
    fibres).[6]

    Summary 1.2 Signalling events
    As previously mentioned in sections 1.2.2 and
    1.2.3, RE-induced hormonal and immune responses
    increase satellite cell activity (i.e. activation, proliferation and differentiation). Hormones and cytokines activate these normally quiescent satellite cells and subsequently cause them to proliferate,
    differentiate and fuse to existing muscle fibres.
    Satellite cells thus contribute new nuclei to the existing pool within the muscle fibre. This is critical,
    because increasing the number of myonuclei en-
    hances the fibre’s capacity for transcription, protein
    synthesis and growth. The importance of satellite
    cells for muscle hypertrophy has been clearly dem-
    onstrated, as irradiation (a potent inhibitor of satel-
    cell activity) negates the increase in myonuclei,
    DNA content and muscle size that normally occurs
    following muscular overload.[51]

    SUmmary 1.3 Protein SYnthesis
    Together, these results indicate that translational
    efficiency (i.e. mRNA translated per ribosome) is important for acute increases in protein synthesis
    during the initial hours/days of overload; however, increased transcriptional capacity (i.e. quantity of nuclei)
    via satellite cell fusion, and perhaps increased
    translational capacity (i.e. quantity of ribosomes),
    critically regulate long-term gains in muscle
    size.

    Summary 2.1 Exercise Choice
    Altogether, these studies indicate that, when muscle
    tension is equated, different muscle actions produce
    similar responses and adaptations. However, eccentric actions seem to be a more potent stimulus for
    muscle signalling because greater muscle tension
    can be developed. Although these findings indicate
    that eccentric muscle actions must be included to
    optimize adaptations to RE, disproportionate
    volumes of supplementary eccentric muscle actions
    might be counter-productive, as excessive muscle
    damage might ensue.

    Exercise load might impact the detection of sig-
    nalling responses following RE. Humans possess muscle
    groups of mixed fibre type, yet analysis of muscle
    signalling proteins typically requires homogenization
    of the muscle sample. Human muscle
    homogenate contains an array of type I, type IIa, and
    type IIx muscle fibres, eliminating the ability to
    analyse fibre type-specific results. This is relevant
    because the load employed during RE strongly affects motor unit (and hence, muscle fibre) recruitment. For example, low-load RE protocols might not recruit type II motor units (as suggested by the size principle), unless the exercise is performed explosively and/or there is significant muscle fatigue. Therefore, low-load RE protocols might result in significantly different signalling responses compared with heavy-load RE protocols. This is an important consideration, given that muscle contrac-
    tion-induced increases in p70 S6K phosphorylation
    occur mainly in type II muscle fibres.[4]

    Summary 2.4 Rest Periods

    In summary, the direct influence of rest periods on mediating RE- induced muscle signalling responses is largely unexplored. Therefore, it is recommended[83] that short rest periods can be used to stimulate hypertrophy and that long rest periods are used to maximize strength gains.

    Summary 2.5 Exercise Order

    The degree to which exercise order alters signalling responses to RE likely depends on the magnitude of change required of the other exercise variables (e.g. reduced 3. load and/or volume, increased rest) to compensate for altered neuromuscular performance.

    3. Conclusion
    RE-induced muscle growth is an intricate, multifaceted process. Recruitment of motor units to produce force causes mechanical deformation of muscle fibres and stimulates hormonal and immune/inflammatory responses. These ‘upstream’ factors independently (and in some cases, inter-dependently) influence various muscle cell signalling pathways. In particular, the immediate response of the mTOR pathway and the prolonged influence of satellite cell activity are critical for mediating muscle growth. Manipulation of the acute RE programme variables (i.e. exercise choice, load, volume, rest periods and exercise order) dramatically impacts the
    signalling responses and subsequent adaptations to RE.
     
  2. beingisbeing

    beingisbeing New Member

    <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">
    In summary, the direct influence of rest periods on mediating RE- induced muscle signalling responses is largely unexplored. Therefore, it is recommended[83] that short rest periods can be used to stimulate hypertrophy and that long rest periods are used to maximize strength gains.</div>

    I would think the opposite...

    Long rest periods= letting the CNS recover so it can &quot;get out of the way&quot; of exerting maximum tension force. ie., now I waited an extra minute and I can subject my muscles to a work load of 100lb X 5, lets say.

    Short periods= tiring out the CNS and getting &quot;in the way&quot; of maximal stimulation to the muscle. ie., I can't do 100 lbs X 5 not because its overloading my muscle but because I need another 60 secs to breath, to recuperate neurally, etc...
     
  3. Aaron_F

    Aaron_F New Member

    So you think its best to have a short rest period to gain strength?

    yeah, ok.
     
  4. beingisbeing

    beingisbeing New Member

    <div>
    (Aaron_F @ Jun. 25 2008,7:04)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">So you think its best to have a short rest period to gain strength?

    yeah, ok.</div>
    I didn't say anything of the sort did I? Denial of a statement doesn't amount to assertion of its opposite does it? Maybe a course in logic would sharpen up your formidable research/scientific capacities, my mentor friend [​IMG]

    I didn't reverse the proposition: long rest-->strength, short rest--->hypertrophy.

    I said I think long rest would be better for hypertorphy, and I stated a reason why I think that.


    If you want to tell me why I'm wrong I'd love to hear, I've learned alot from ya already buddy... [​IMG]
     
  5. Aaron_F

    Aaron_F New Member

    Well the origonal statement was &quot;Therefore, it is recommended[83] that short rest periods can be used to stimulate hypertrophy and that long rest periods are used to maximize strength gains.&quot;

    and you said

    &quot;I would think the opposite...&quot;

    you didnt state which one you were talking to adn teh other comments were not particularly clear for anything else. So that would leave the proposition that you reversing their origonal statement.

    But &quot;I said I think long rest would be better for hypertorphy, and I stated a reason why I think that. &quot;

    you did? where


    <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">I would think the opposite...

    Long rest periods= letting the CNS recover so it can &quot;get out of the way&quot; of exerting maximum tension force. ie., now I waited an extra minute and I can subject my muscles to a work load of 100lb X 5, lets say.

    Short periods= tiring out the CNS and getting &quot;in the way&quot; of maximal stimulation to the muscle. ie., I can't do 100 lbs X 5 not because its overloading my muscle but because I need another 60 secs to breath, to recuperate neurally, etc... </div>
     
  6. beingisbeing

    beingisbeing New Member

    <div>
    (Aaron_F @ Jun. 25 2008,9:20)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Well the origonal statement was &quot;Therefore, it is recommended[83] that short rest periods can be used to stimulate hypertrophy and that long rest periods are used to maximize strength gains.&quot;

    and you said

    &quot;I would think the opposite...&quot;

    you didnt state which one you were talking to adn teh other comments were not particularly clear for anything else. So that would leave the proposition that you reversing their origonal statement.

    But &quot;I said I think long rest would be better for hypertorphy, and I stated a reason why I think that. &quot;

    you did? where


    <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">I would think the opposite...

    Long rest periods= letting the CNS recover so it can &quot;get out of the way&quot; of exerting maximum tension force. ie., now I waited an extra minute and I can subject my muscles to a work load of 100lb X 5, lets say.

    Short periods= tiring out the CNS and getting &quot;in the way&quot; of maximal stimulation to the muscle. ie., I can't do 100 lbs X 5 not because its overloading my muscle but because I need another 60 secs to breath, to recuperate neurally, etc... </div></div>
    hahahaha. between the spelling and grammatical errors I really can't tell if you're joking...?

    To rephrase more clearly, I would think that long rest periods are def better for hypertrophy, strength, I have no idea. the REASON being delaying/attenuating CNS fatigue and thus allowing the muscle to be fully loaded.

    I was under the impression that one of Bryan's main principles, is that 'fatigue' as we usually think of it, (i.e. failure) has jack diddley to do with hypertrophy. its more a neural issue.


    so anyway, why are things the way the research says the are? or 'guesses' they are, as it admits there doesn't seem to be much research?!
     
  7. Aaron_F

    Aaron_F New Member

    <div>
    (beingisbeing @ Jun. 26 2008,4:23)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">hahahaha. between the spelling and grammatical errors I really can't tell if you're joking...?</div>
    Great coming from somebody who's original post was as clear as mud, but always good to see the grammar police coming into a discussion, its a fish, a sort of a herring, somewhat red.
     
  8. dkm1987

    dkm1987 New Member

    There is very little direct research looking at how rest impacts the molecular side of things. One study looking at rest times, strength and hypertrophy shows that either 2 or 5 minute rest produces about the same effect but the methods in that particular study are somewhate questionable.

    So this is an area that I personally feel needs more research.

    Strength research and recovery or maintainence of strength with varying rest times has been more conclusive, IMO anyway.

    As Speiring points out in this opinion, fatigue may have a place but it mostly revolves around recruitment and hence activation of the fibers (mostly fast fatiguable) but there are more than one way to skin a cat and fatigue itself still isn't necessary to get activation levels peaked.

    Again IMOO, if one wishes to increase fatigue threshold then one must train that system but if strength and or hypertrophy is the main concern then I don't see were high fatigue is needed.
     
  9. spax

    spax New Member

    <div>
    (Dan Moore @ Jun. 25 2008,8:23)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">
    In summary, exercise load, rate of force development, and muscle fatigue affect motor unit recruitment during RE. Motor unit recruitment (and the phenotype of the recruited motor units) must be carefully considered for responses and adaptations to RE because: (i) only those motor units recruited will respond and adapt to RE; (ii) heavy loads, explosive exercises, and/or significant muscle fatigue is necessary to activate type II motor units; (iii) type I and type II muscle fibres display differential signalling responses to muscle contraction; (iv) type II muscle fibres have a greater capacity for hypertrophy following RE training than type I fibres;[5]

    ...This is relevant because the load employed during RE strongly affects motor unit (and hence, muscle fibre) recruitment. For example, low-load RE protocols might not recruit type II motor units (as suggested by the size principle), unless the exercise is performed explosively and/or there is significant muscle fatigue. Therefore, low-load RE protocols might result in significantly different signalling responses compared with heavy-load RE protocols. This is an important consideration, given that muscle contrac-
    tion-induced increases in p70 S6K phosphorylation occur mainly in type II muscle fibres.[4]</div>
    Bingo!  Low-loading can be used if there is significant fatigue present: &quot;the last rep is the most important&quot; type of training.  This is why almost everyone will grow off standard bodybuilding lifting.  However, the molecular signalling will differ between low- and high-loading.  This will lead to different muscular adaptations over time.  Another way to increase recruitment with low-loading is to lift explosively, i.e. power training.  This has further applications for those involved in sporting endeavors.  Overall, another interesting summary report. Thanks Dan.
     
  10. spax

    spax New Member

    <div>
    (beingisbeing @ Jun. 25 2008,5:29)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE"> <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">
    In summary, the direct influence of rest periods on mediating RE- induced muscle signalling responses is largely unexplored. Therefore, it is recommended[83] that short rest periods can be used to stimulate hypertrophy and that long rest periods are used to maximize strength gains.</div>

    I would think the opposite...</div>
    You might want to reread the abstract, and what you posted.
     
  11. beingisbeing

    beingisbeing New Member

    <div>
    (Aaron_F @ Jun. 26 2008,4:11)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE"><div>
    (beingisbeing @ Jun. 26 2008,4:23)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">hahahaha. between the spelling and grammatical errors I really can't tell if you're joking...?</div>
    Great coming from somebody who's original post was as clear as mud, but always good to see the grammar police coming into a discussion, its a fish, a sort of a herring, somewhat red.</div>
    sorry if I hurt your feelings big A

    My original post may have been muddy, but it was you who began with the sarcastic crap, which I usually enjoy, IN LIEU of constructive criticism of what I said.

    I figured since I routinely ask you questions and listen graciously, a little banter wouldn't be so out of place, especially given your sarcasm and wit that we all enjoy. I mean that, not being sarcastic.

    however, I too, am a sarcastic prick. if you can't deal, maybe you should go hang out with martin levac on the planet of 'don't challenge me'

    for the record, I put the axe down, and asked you for an explanation in the previous post.

    who cares anymore anyway. your posts/ideas have put me on track more than once, and I'm sure they will continue to do so.

    love ya Aaron [​IMG]
     
  12. beingisbeing

    beingisbeing New Member

    <div>
    (Dan Moore @ Jun. 26 2008,9:02)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">There is very little direct research looking at how rest impacts the molecular side of things. One study looking at rest times, strength and hypertrophy shows that either 2 or 5 minute rest produces about the same effect but the methods in that particular study are somewhate questionable.

    So this is an area that I personally feel needs more research.

    Strength research and recovery or maintainence of strength with varying rest times has been more conclusive, IMO anyway.

    As Speiring points out in this opinion, fatigue may have a place but it mostly revolves around recruitment and hence activation of the fibers (mostly fast fatiguable) but there are more than one way to skin a cat and fatigue itself still isn't necessary to get activation levels peaked.

    Again IMOO, if one wishes to increase fatigue threshold then one must train that system but if strength and or hypertrophy is the main concern then I don't see were high fatigue is needed.</div>
    thank you Dan, as always.

    I guess in the back of my mind was your idea of M time, and the notion of fatigue being mostly metabolic.

    So I was thinking, longer rest period=less fatigue=higher capacity to load the muscle=more hypertrophy
     
  13. Aaron_F

    Aaron_F New Member

    <div>
    (beingisbeing @ Jun. 27 2008,8:15)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">sorry if I hurt your feelings big A

    My original post may have been muddy, but it was you who began with the sarcastic crap, which I usually enjoy, IN LIEU of constructive criticism of what I said.

    I figured since I routinely ask you questions and listen graciously, a little banter wouldn't be so out of place, especially given your sarcasm and wit that we all enjoy. I mean that, not being sarcastic.

    however, I too, am a sarcastic prick. if you can't deal, maybe you should go hang out with martin levac on the planet of 'don't challenge me'</div>
    Sarcastic? not really. But I am glad you put in the effort to think I was.

    <div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">for the record, I put the axe down, and asked you for an explanation in the previous post.</div>

    and you had answered what I had questioned in the previous post, in between throwing out more fish than a chinese restaurant and claiming they had written words that were not there, but if they were, could have made a bit more sense.

    but the questions were not much for me, as I do not care enough to delve into that angle, which is where dan comes in
     

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