7 Secrets You Didn’t Know About Light Versus Heavy Weightlifting

by RN Graham

As gyms across the globe start to reopen, many of us will be lifting lighter weights than we were 3 months ago. But is that such a terrible thing? One group of gym-goers lift weights with the thought “I have got to lift as heavy as I can to get big.” On the other hand, another common sentiment is, “I don’t want to be too muscular, but I want to get toned so I will stick to these lightweights.” So, who is right? Well, it really isn’t that simple, but at the same time, it actually is. There is quite a bit of misinformation out there driven by pride and assumptions. With that said, this week at Maximal Being:  7 Secrets You Didn’t Know About Light Versus Heavy Weightlifting

Defining What Light Versus Heavy Weightlifting Is

Nerding out for a moment, we have to use physics to define what is light versus heavy weightlifting strategy. 

• Light Weight is defined in most studies as lifting under 60% of your 1 rep max (RM)
• Heavy Weight is defined as > 65% of 1 RM
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This means if you can deadlift 350 lbs x 1 rep, your heavyweight would be anything over 227 lbs. and your lightweight under 210 lbs.  Furthermore, let us define the actions being taken on these muscles by each type of lifting.

The Physics of Light Versus Heavy Weightlifting on Muscle

Each muscle action uses:

Tension or the application of force placed on an object in order to generate stretch. 

Stress the force applied on an object over an area.

Given these definitions, one would think that heavyweights would induce more tension on an object and light would perform more repeated stress over time.  The culmination of which would lead to a more tensile resistant (bigger) muscle with heavy loads and a more stress-resistant (due to repeated motions) muscle with like loads.  However, we must remember that muscles include multiple different types of fibers within them, which have variable responses to force.

Within Each Muscle Exist Different Muscle Fiber Types

Enter the slow versus fast twitch muscle fibers. 

• Type I fibers are slow twitch
• Type II fibers are fast twitch. 
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https://www.researchgate.net/figure/NADH-showing-Type-I-dark-and-Type-II-light-myofibers-a-Normal-myofibrillar_fig2_228628116

Using our gym stereotypes above, those that want to build muscle, think that they would grow type I fibers with endurance training and type II with fast bursts of energy like weightlifting.  It turns out that when researchers biopsied the muscles of individuals on heavy versus light programs they both hypertrophied (grew) each type of muscle independent of variation or the type of exercise.

There were variable degrees of something called phosphorylation.  Phosphorylation is the process by which a P or phosphate is added to the light chain of muscle fibers in order to cause a contraction. 

All was well and good, but this led to no ultimate changes in muscle growth between the light versus heavy weightlifting groups.  Keep that concept in mind as we move forward.

The Research Says Light Is Equal to Heavy Weights

All research comparing light versus heavyweight kept volume constant. 

Volume = weight (lbs) x sets x reps

The first well-known of these studies was in 2008, evaluating total body workouts and showing that there was no difference in bulk or strength.  

One issue with this study was that they looked at total body movement and not a specific muscle group.  There also was no biopsy data to look at what is happening under the surface with light versus heavy lifting.  Of course, the researcher was poised to answer that question.

A Deep Dive into Light Versus Heavy Weightlifting Research 

In an article published in the Journal of Applied Physiology, Cam Mitchell, a lead study author and a Ph.D. candidate in McMaster’s kinesiology department, said “We found that loads that were quite heavy and comparatively light were equally effective at inducing muscle growth and promoting strength.” This study looked at a single muscle group (legs) and involved data points like MR-imaging and muscle biopsies.  The end result, despite the change in phosphorylation, there was no difference in hypertrophy on biopsies of strength during the performance. 

This was followed by a study in 2016 again showing no difference in gain in the 49 men who enrolled.  Both light and heavy lifters demonstrated improved performance and an increase in both type I and II muscle fibers.  As discussed above, you can grow both fiber with both light versus heavy weightlifting strategies.  

The usual way that the research is countered is to say something like, “well these studies had a low number of subjects.”  True!  Too few people in studies can alter the results.  To correct this, researchers will then perform a study called a meta-analysis. In these manuscripts, smaller groups of data are bunched together to enhance the participants and perhaps reach new conclusions.  Guess what?!  A meta-analysis was done in 2014 and…there was no difference in strength or hypertrophy.  

However, the authors saw a “trend toward benefit for heavy.”  Honestly, if the data doesn’t show the result…it isn’t there.  Now we all know that research does not always relate to reality, so what do the experts say?

Expert Testimonials Say Light May be Best for Longevity Lifting

In the words of the great Ronnie Coleman, “Light weight baby!”

 

To match the muscle gain achieved from lifting heavier weight the lifter would have to rep to failure. Now, this does not mean that you can grab a 10lb dumbbell and curl it 50 times. Instead, your goal should be 12 or greater with an ideal max failure being around 20-25. If you can complete reps higher than this (with the proper form of course), then it is time to increase the weight.

Want to get hurt working out? Let your pride get in your way. To quote Ving Rhames as Marsellus Wallace,

“F pride (the “F” I’m quite sure stands for forget). Pride only hurts, it never helps.”

Lifting heavy can cause injuries when your form is compromised, especially when pushing yourself too hard and you start using a little too much proper English (Care for a spot of tea?) to try and exceed your limits. Fact is, the better your form, the better your results. With lighter weights, you can concentrate on executing the full range of motion while keeping your body alignment intact. Make your muscles do the work. Lifting light is also beneficial when you are trying a new exercise or a more complicated exercise for the first time. Once again, you are more focused on the form and the function.

When exercising with lightweight, you can focus on the contraction of your muscle fibers allowing for better hypertrophy of the targeted muscle or muscle groups. Yes, watching someone push a ton of weight is quite impressive, but so is staying injury-free.

Add a Light Weight to Spice Things Up

Want to heat your cardio up? Add 3-pound weights to your time on a stationary bike. It may not seem like that much but try doing a set of curls for 30 seconds rest for 1 minute (keep those legs going though) and then repeat.

Do this during a 30-minute ride to see how quickly 3-pounds start to add up. Want another challenge? Invest in a weight vest with about 15-20lbs of weight and go for a nice hike or set your treadmill to max incline. Make sure to stay well hydrated!

Lift Heavy for Fun Not Just for Muscle Mass

Heavyweights without a doubt give you the most bank for the buck, it is just more efficient. Think about it. Why spend time lifting 20 pounds 16 times when you can have the same results doing 40 pounds for 8 reps. The key is VOLUME.  Just doing the action will induce the tension and stress needed to cause hypertrophy and gainz!

Once again this comes down to form. Yes, lifting heavy weights can get you to your goal of fatigue faster. You may use more compensatory muscles or body movement to generate force.  This is a recipe for injury.  Also, heavyweights have a greater risk of injury than their lighter counterparts, make sure you have a spotter. 

Summary

My answer to you is to do both. Research shows us that depending on the outcome you are chasing, there is a good chance that you can obtain your goal doing either.  You can and will build type I, II fibers, hypertrophy, gain strength in one of many muscle groups with BOTH.  The difference may be in how long you can have your gains.  For longevity consider light.  Otherwise, the research and us at maximalbeing.com say, you can get there either way.