How do I know if I should lift heavy or lighter?

By Del Baldwin
January 11, 2021

This is one of the most common questions I get. Here is the basic answer: It depends. But it’s not complicated. These are the questions to ask yourself:

• Are your joints healthy?  
• Do you have any joint pain?  
• How many reps/what is the timing of your set?

If you have healthy joints and no pain, do not be afraid to go heavy, but expect to do less reps.  If there is a higher rep goal, choose lighter weights.  Here are some general guidelines:

• More than 12 reps or more than :45 seconds= always go lighter so you can finish successfully in good form.  
• 8 or less reps, :30 or less= heavier
• 8-12 reps, :30-:45 seconds: (most common) Go with a challenging, but not terribly hard weight set.  You want to be struggling by 10 but still in good form and not at risk for hurting yourself.

If you experience pain or have unhealthy joints, always go with the lighter options and try to get more reps in.  

Here is the math.  Whether you do 10 reps at 20 pounds or 20 reps at 10 pounds, you are still pushing or pulling 200 pounds total.  Do more reps with less weight if you experience any pain, you still get the work!

If this is something that interests you, here is some more information.  Your instructor should be considering the following:

• Where is the weight according to the joints working? (or “How long is the lever?”)
• How large is the joint at work and its major moving muscles?
• How many joints are working during this exercise?

A good instructor will say “grab lighter weights for this one” when switching from one exercise to the next according to these criteria.

An example of “longer” lever would be a lateral raise.  The distance between the shoulder (the joint working) and the weight is long, so you would choose a lighter weight.  Think of the difference between that and a bicep curl, where the joint working is your elbow–a much shorter lever, so a heavier weight.

As for the size of the joint (LOL, read that again!), think of the size of your hip complex and all the huge muscles supporting it versus the size of your knees.  You can go heavier with a deadlift where the joint is the hips, than you can with a squat, which is knee-dominant exercise.  

As for the “number of joints working”….a bicep curl or tricep kickback use one joint, the elbow, so automatically there are less muscles being recruited.  These are very focused movements.  But now think of an overhead press or pushup.  Shoulders, elbows, wrists.  Many muscles.  And many larger muscles (back, chest) so you can go heavier the more joints are working and the more muscles recruited.

Another fun fact:  The more joints at work and the more muscles recruited, the more calories you are burning!

Gravity is another force at play for consideration, but that is on the instructor!  If you are not working with an instructor, please pay close attention to how your body feels and choose wisely.  Exercise should be fun, but it can be serious business, too.  The most important thing is to err on the side of safety.