Cris LaBossiere

Cris LaBossiere
Strength training and mountain biking. My two favorites

Sunday, May 30, 2010

Losing Muscle Mass Associated With Type II Diabetes Risk

We've all heard about the risk of developing type II diabetes from being very overweight or obese.  It has been speculated that too little muscle mass carries a similar risk.

A study done at UCLA found a correlation between sarcopenia (loss of lean muscle mass) and insulin resistance.  Insulin resistance is a key variable that is involved in the development of type II diabetes.

In a cross sectional analysis of over 14,000 study participants reduced muscle mass was associated with both the obese and non-obese. 

The researchers say that both obesity and sarcopenia are independently associated with adverse glucose metabolism; being either too skinny or too fat can negatively affect glucose metabolism.

When dieting to lose body fat, many dieters don't do enough (or any) strength training and as a consequence many lose fat (which is good), but also lose lean muscle mass.  

Bone density and muscle mass are correlated to a large degree as the physical exercise required to stimulate muscle growth can also increase bone density. Avoiding exercise will cause a decrease in lean muscle mass, and also decrease bone density. However, the exercise has to be fairly challenging to get the bone density and muscle mass benefits.  To increase bone density exercises that load bones along the length of the bone appear to make a bigger difference to bone density compared to exercises that place force across the bone.

To clarify, lifting weights with your legs while standing (squats, lunges) would place a compression force along the length of your leg bones from your hips to your heals.  Doing a seated knee extension exercise places a force across the width of only your lower leg bones and does not stimulate bones to increase density.  A seated leg press will load your leg bones the same way the standing leg exercises does.

Gaining muscle mass requires some effort, but going too hard too soon will increase risk of injury so it's best to start slow and easy, and gradually increase your muscles ability to tolerate more challenging loads.

There are numerous benefits to increasing and maintaing muscle mass:

  • Increased strength.  This makes any daily task much easier to complete, and increases your options to participate in many physical activities
  • Maintain and increase mobility while ageing.  Much of the reduced mobility as we age is associated with sarcopenia from disuse.  This is a use it or lose it thing.  Many seniors would be able to retain full mobility or a greater portion of their mobility by continuing with regular exercise, including challenging strength training exercises designed to increase lean muscle.
  • Neurogenesis.  All exercise stimulates brain cell development.
  • Increased cognition.  All exercise increases cognitive function. 
  • Reduces risk of slip and fall.  Important for seniors who are at increased risk of bone fracture, but this benefit also benefits younger populations.. who likes falling down?
  • Increased muscle mass and bone density

Studies show that those in their 60's, 70's, and even 80's and 90's still respond to and benefit from strength training, increasing both muscular strength and size, along with physical mobility.

Important to know.. between ages 65 to 75 our ability to maintain muscle mass after injury and disuse decreases.  After a muscle injury, the healed muscle usually retains most or all of it's contractile fibres.  However the ability to repair muscles reduces between ages 65 to 75 and a much larger portion of the injured muscle after healing will become non-contractile fibre tissue.  This is another reason to place a great deal of importance to regular strength training as we age.  It's best to enter our 60's and 70's with as much muscle mass as possible.  I'm not suggesting everyone become bodybuilders or go extreme as this isn't necessary for the health benefits I'm talking about here, just once or twice week of challenging strength training is enough.  Having said that, if you've decided to get into bodybuilding, keep it up;  it's not just about getting big muscles, it's about health.

Once a person has graduated though the process of starting easy, learning proper technique, and building tolerance to more difficult weight training there are many options, but a safe start is gradually building up to doing 1 to 3 sets of around 30 repetitions using a weight heavy enough to make 30ish repetitions feel like that's all you can do.  Don't start out this hard though, start with fewer repetitions and stop lifting before it feels like fatigue forces you to stop.

Starting too hard doesn't make gains come any faster in the long run because going too hard can cause extra fatigue, soreness, and injury that prevents you from doing regular exercise.  The old standard of 2-3 sets of 8-12 reps is valid for increasing muscle mass and strength, but recent research has shown that high reps also increase muscle mass to the same degree, but the lighter weight is safer to lift for those starting out.

When thinking about weight training, think about the health benefits.  This really is something we need to do on a regular basis.  When focussed too much on getting bigger or stronger we can lose our way and subject ourselves to unhealthy amounts of exercise; going too hard to chase unrealistic goals.

If you're overweight and losing weight with good nutrition practices, it's very important to add strength training to overcome the risk of sarcopenia that is associated with dieting to lose fat.

If you're conscientious about losing weight and thinking about reducing your risk to type II diabetes, unless you have sufficient muscle mass, the diet alone may not offer the protection you're looking for.

New to weight training? It's a good idea to have an assessment done by a qualified trainer and get some instruction on proper technique.

PLoS ONE: Sarcopenia Exacerbates Obesity-Associated Insulin Resistance and Dysglycemia: Findings from the National Health and Nutrition Examination Survey III

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