Thursday, June 21, 2012

Use It Or Lose It


A contributing factor to the loss of muscle mass and strength with adult aging is the reduction in the number of functioning motor units (MUs). Recently, we reported that lifelong competitive runners (master runners = ∼66 yr) had greater numbers of MUs in a leg muscle (tibialis anterior) than age-matched recreationally active controls. This suggested that long-term exposure to high levels of physical activity may limit the loss of MU numbers with adult aging. However, it is unknown if this finding is the result of long-term activation of the specifically exercised motoneuron pool (i.e., tibialis anterior) or an overall systemic neuroprotective effect of high levels of physical activity.
Purpose: The purpose was to estimate the number of functioning MUs (MUNEs) in the biceps brachii (an upper body muscle not directly loaded by running) of nine young (27 ± 5 yr) and nine old (70 ± 5 yr) men and nine lifelong competitive master runners (67 ± 4 yr).
Methods: Decomposition-enhanced spike-triggered averaging was used to measure surface and intramuscular EMG signals during elbow flexion at 10% of maximum voluntary isometric contraction.
Results: Derived MUNEs were lower in the biceps brachii of runners (185 ± 69 MUs) and old men (133 ± 69 MUs) than the young (354 ± 113 MUs), but the old and master runners were similar.
Conclusions: Although there were no significant differences in MUNE between both older groups in the biceps brachii muscle, with the number of subjects tested here, we cannot eliminate the possibility of some whole-body neuroprotective effect. However, when compared with the remote biceps muscle, a greater influence on age-related spinal motoneuron survival was found in a chronically activated MN pool specific to the exercised muscle.

You already know that as you age you lose muscle, and you may know that an estimate is that you lose 6% per year of muscle unless you engage in strength training, which is estimated to slow the rate of muscle loss to 1%. 

As a side note, the fact that Louie Simmons is powerlifting in the neighborhood of 700 pounds in the deadlift, 800 pounds in the back squat, and 600 pounds in the bench press at age 60+ is ... well, I don't know what to say about that except that Louie is one incredible lifter.  I doubt he has any serious contenders for the title of "World's Strongest 60 Year Old."  Yes, I know powerlifters use funny lifting suits and they are not shy about their use of drugs which allow them to train harder, some of which are of questionable legality.  Still - that's a lot of hard work and determination and guts.

If I read this abstract right, the short version is that it appears you delay muscle loss for those muscle you put to work.  The authors hope there's a systemic benefit, but this test did not show that effect. 

In other words, common sense prevails - if you want to sustain your ability to move yourself around as you age, train all the functions of the body.  Run, jump, climb, push, pull, lift and press.  If you want to maintain the ability to generate power (speed and force), you must train with explosive elements (punching, kicking, throwing, oly lifting, jumping, sprinting).  This stuff isn't, as the old joke goes, rocket surgery.

1 comment:

  1. Paul, while this conclusion is pretty much predictable, I am still searching for the holy grail of programming to optimize the strength/conditioning or MUNE levels for 65 year olds. buck