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Q & A:  Are light weights better for toning your body?  Are they safer?



A: No on both accounts. If you are a masochist light weights can be as effective as moderate or heavy weights for toning.  If you are looking at the big picture of safety, then light weights are less safe.  Let’s break that down.

What exactly is light or heavy?

To be exercise-sciency a light weight would be <65% of your one rep max.  Heavy is >85% of your one rep max.  Your one rep max is the load you can lift one time and one time only. 

The light weight above would be a weight you could lift at least 20 times, but probably more if you are a woman because women tend to have better strength endurance than men.  85% of your one rep max (heavy) would be something you could lift about 6 times, but most women can do more because of their superior strength endurance.

We don’t track our client’s one rep max because getting that number is time consuming, dangerous and useless in practice. 

As you can see, light and heavy are not related to the number of pounds or kilograms you are lifting, but, rather, how many times you could possibly lift it.  “Light” or “heavy”, going to failure or near failure is hard, and it all ends up feeling heavy when your muscles are exhausted!

Light weights not better for tone?

Lifting light weights to failure or near failure is literal torture.  Because your muscles start burning pretty bad by the time you get to rep 12 or 15, it is really hard to keep going until you hit rep 40 or 50 to hit failure with a light weight.  Most people will stop at 20 because of the painful burn.  Stopping at 20 when failure is 40 means you worked at 50% effort… in other words, sets of 30-40-50 reps hurt so bad, that only true masochists will go to failure.

A medium load that you can do 10 times doesn’t take as much mental effort to push to failure or near failure. In other words, heavier loads make it more likely that someone will work at the appropriate intensity to burn off the fat and, at least, maintain their muscle mass.

Lighter weights are not safer?

So, in one sense, lifting something that is very easy for you to lift is going to be very safe because there’s so little tension on your muscles.  However, the safety you purchase by doing very easy exercise is at the price of durability and safety over time.

Our bodies need stress to be healthy and strong.  When astronauts go into space the stress of gravity is removed from their bones, muscles and heart, and, as a result their bodies age at light speed.  Every system weakens, and they lack the strength to walk when they return to Earth’s gravity. 

This – removing gravity – is one of the downsides to relying on swimming and/or biking for most or all of your exercise – both of these modes of exercise unload your skeleton, and therefore allow your skeleton to lose mass and strength. 

Our bones need substantial force applied through them on a regular basis to maintain themselves, and even more to reverse course and get stronger.  Doing easy exercise means you’re not stimulating your skeleton, ligaments, tendons, or muscles to maintain themselves, let alone get stronger and more resistant to breaks or tears.

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