Muscle Hypertrophy (bigger muscles!)Below is a great brand new review of what makes a muscle bigger! Sweet! Here are some take aways to keep in mind.
In general, muscle types can be broadly defined as Type I or Type II.
Slow Twitch (Type I)
These guys are slow muscles and they are more efficient at using oxygen (aerobic) for continuous, extended muscle contractions over a long time. They are a friend to all the cardio bunnies. As the name states, they contract more slowly than fast twitch fibers too.
Fast Twitch (Type II)
Fast twitch fibers use anaerobic metabolism (think NO oxygen) and work best to created short bursts of strength or speed as compared to the Type Is. The downside is that they get tired (fatigue) more quickly. Think of sprinting---you can go very fast, but you can't go fast AND long distances.
Type IIs are almost more prone to hypertrophy (increasing in size) and are a friend to weight trainers and power/speed athletes. I would argue they are a friend to all since they keep you more "functional" as you age.
Study Highlights
The study also states, "Eccentric resistance training has been shown to be highly efficient in inducing sarcomeric protein assembly in the longitudinal orientation of muscle cells."
What? Eccentric (lowering of weight) may help you increase muscle size! It also may make you crazy sore too. I once (er, I mean I heard about a g
uy) in college that did too much calf work and included heavy eccentrics for too many reps and walked like a friggin penguin for a week. Those crazy college kids!So don't just go crazy on the ecentrics as the study states, "concentric contractions lead to a hypertrophic response (increased fiber diameter) in muscle which can still be activated in old age."
Yep, you can to be strong as you age!
Last key point, "The central signaling pathway to mediate the elevation of protein synthesis in response to training is the mTOR pathway, which is also stimulated by free amino acids."
mTOR is the pathway stimulated by protein. So protein by itself is very anabolic (building) in nature.
Stimulate the muscle + protein and calories= increased muscle size! Viola.
Converting Type IIs to Type Is?
They also talk about doing some endurance training at a low intensity and for longer than 30 minutes to help convert Type IIs to Type Is. Yikes! Personally, I want to keep as many Type II fibers as possible; so based on this study you would want to keep your "cardio" work to UNDER 30 minutes and do more high intensity work. Yet another reason for Kettlebell CRF (cardiorespiratory fitness) work instead of jogging. Keep off that darn treadmill too. You can even push your car, pick up something heavy and walk around with it, get a sledge hammer and pound away on a tire, etc.
Any questions, comments, post away! Let me know what you think
Rock on
Mike T Nelson
[Exercise and cellular adaptation of muscle.]
Tegtbur U, Busse MW, Kubis HP. Institut für Sportmedizin, Medizinische Hochschule Hannover , Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland, tegtbur.uwe@mh-hannover.de.
Resistance training and to a lesser extent endurance training are capable of enhancing protein synthesis in skeletal muscle via various signaling pathways. Additionally, the expression of muscle fiber types responds to different regimes of training stimuli and immobilization as characterized by changes in myosin heavy chain isoforms (I<-->IIA<-->IIX). Eccentric resistance training has been shown to be highly efficient in inducing sarcomeric protein assembly in the longitudinal orientation of muscle cells. However, concentric contractions lead to a hypertrophic response (increased fiber diameter) in muscle which can still be activated in old age. The central signaling pathway to mediate the elevation of protein synthesis in response to training is the mTOR pathway, which is also stimulated by free amino acids.
Moreover, adaptation to endurance training is mediated by the calcium-calcineurin-NFATc1 pathway which is strongly activated by the calcium transients involved in the muscle contraction process. High contraction frequency and long duration of training sessions are essential for activation and maintenance of fiber type I expression as well as for induction of transformation of type II into type I fibers. Endurance training sessions should therefore be longer than 30 min and dominated by periods of high frequency contractions. A further factor in the muscular response to training includes the recruitment and integration of satellite cells into muscle fibers. Satellite cells can respond to muscular stretch, activity and injury with increased proliferation and can later be integrated into muscle fibers.
CONCLUSION: Therefore, new myonuclei are available to enhance mRNA synthesis and protein expression in muscle cells. New understanding of the cellular mechanisms of signal transduction in muscle in response to training, bed rest and ageing will help to optimize training and interventions in an ageing population.
