High-Intensity Resistance Training with Insufficient Recovery Time Between Bouts Induce Atrophy and Alterations in Myosin Heavy Chain Content in Rat Skeletal Muscle.
The conclusion
These data show that high-intensity resistance training with insufficient recovery time between bouts promoted muscle atrophy and a transition from slow-to-fast contractile activity in rat plantaris muscle
Pretty much the relationship between intensity and frequency/volume that Arthur Jones brought to the attention of the resistance training community in the 1970's. Unless you allow recovery to happen supercompensation will never occur and eventually the body will decompensate.
I found it interesting though that the atrophy was predominantly of the slow twitch fiber types (I and IIa) and a transition back towards a more fast twitch profile was noted.
High intensity resistance training actually promotes a fiber phenotype transition from type IIb towards type IIa but I guess insufficient recovery promotes selective atrophy in the opposite direction.
Interesting, but not surprising. Fast twitch fibers tend to require longer to recover, so inadequate recovery time would tend to favor adaptation of or conversion to slow twitch.
ReplyDeleteBut insufficient recovery in this study actually caused a phenotype change toward a more type IIb profile. So a shift from type I and IIa towards more type IIb.
ReplyDeleteAMPK activation through HIT stimulates conversion from type IIb towards more oxidative type IIa, but it seems insufficient recovery interferes with this and perhaps even reverses the stimulated changes.
“Unless you allow recovery to happen supercompensation will never occur and eventually the body will decompensate.”
ReplyDeleteIt is worse than that--muscles frequently not allowed to recover between workouts will be damaged, turn to scar tissue, which eventually will be replaced with fat deposit. This end result of muscle abuse is called fatty atrophy. Unlike the atrophy of disuse, the atrophy of abuse cannot be reversed.
“I found it interesting though that the atrophy was predominantly of the slow twitch fiber types (I and IIa) and a transition back towards a more fast twitch profile was noted.”
Here is a fact to ponder:
People with chronic back pain have a greater ratio of glycolytic FT fibers in their back muscles, which makes those muscles less resistant to fatigue (Biedermann et al. 1991 [http://www.ncbi.nlm.nih.gov/pubmed?term=1836678], Mannion et al. 1997 [http://www.ncbi.nlm.nih.gov/pubmed?term=9497814]).
Tom,
ReplyDeleteThanks for commenting!
Fatty infiltrations are common in CLBP too.
http://www.ncbi.nlm.nih.gov/pubmed/8504225
http://radiology.rsna.org/content/240/3/786.full
Though its not correlated with duration of symptoms. Makes it difficult to deceipher whether it's disuse atrophy or overuse atrophy and there are differing opinions on either.
I've seen the Mannion et al paper but not the Biederman et al. I am always skeptical of EMG studies though it would be interesting to see the methodology and full discussion in the full paper.
The fact that type IIb fibres are more predominant in CLBP is maybe another reason why guys like McGill are adamant that 'endurance' is the key. They may be right and fatigue resistance is more important in terms of withstanding cumulative load as opposed to heavier loads. But the finding still justifies a high intensity resistance training approach as it promotes phenotype translation towards a type IIa profile.