Heavy weights or low weights – what’s the research say?

By Ben Dearman

As a gym that has “KNOWLEDGE” in our name, we take great pride in following the latest research and comparing it to what we currently do in the gym as well as the results our members get.


Because of that we belong to a number of research reviews that provide us with the most up to date cutting edge knowledge about fitness, nutrition and the like.


This article was recently highlighted in one of our research reviews (basically, really geeky exercise and nutrition scientists that sift through the 100’s of published research studies every month to bring the crème de la crème to the other exercise and nutrition geeks that don’t have the time to look through those journals…like us!)




In summary the article states this:

– Forty-nine resistance-trained men performed 12 wk of whole-body resistance training.

– Subjects were placed into either a group that lifted light weights for 20-25 repetions or into a group that lifted heavy loads for 8-12 repetitions.  Both groups performed the lifts to volitional muscle failure, i.e. not true muscular failure but basically to the point where they said, ok, we’ve had enough.

– Skeletal muscle biopsies, strength testing, dual- energy X-ray absorptiometry scans, and acute changes in systemic hormone concentrations were examined pre-training and post-training.

– In response to RT, 1RM strength increased for all exercises in both groups.

– Fat- and bone-free (lean) body mass and type I and type II muscle fiber cross-sectional area increased following training with no significant differences between groups.  They added lean body mass and bone mass equally between the two groups.


The data showed that in resistance-trained individuals, load, when exercises are performed to volitional failure, does not dictate hypertrophy or, for the most part, strength gains.


That means – whether you are doing 25 reps or 8 reps, it’s the load WHEN PERFORMED TO VOLIITIONAL FAILURE (the weight needs to be heavy enough so that once you get to the prescribed reps you REALLY don’t want to do any more, but if need be you could squeak out a few more reps).


So that seems pretty cut and dry – whether you lift heavy weights or light weights you will experience the same results.


More to the story

However, there is a saying I like to use in the gym – The expression of strength in the gym allows you to realize that strength outside of the gym.  Being strong requires you to PRACTICE strength.  If I can lift 400 pounds for one rep in the gym after I warm up, then I should be able to lift 50% of that with no warm up.  Or if I can lift 135 pounds for 15 reps with a warm up, then I should be able to lift half of that with no warm up.  Or to put it another way, lift roughly 70 pounds for at least 45 seconds (the average amount of time it takes to lift 15 reps).


There are a few things to note about this study:

  1. It’s only one study.
  2. It only looks at males and young ones at that (average age was 24).
  3. The males were experienced lifters (with at least two years of lifting).
  4. The participants stopped when they wanted to. That alone can really skew a lot of things as opposed to stopping when they physically could not perform another rep, i.e. true muscular failure.
  5. The movements they picked were about half cable and half machine. NOT optimal by any means, but for this study, adequate.


We want our members to be as lean as possible and as strong as they can be (after all, our ability to move relative loads is ultimately what determines our potential to injury as well as our ability to move relative loads…i.e. picking up a heavy suitcase, or walking up a flight of stairs carrying an air conditioner or slinging a bag of pellets over your shoulder), and contrary to what this article might say – there are metabolic, hormonal and biological benefits to be had by lifting in the three spectrums of rep range – low reps (under 8), mid reps (8-12) and higher reps (15+).


That’s why we hit all three in a week!

Working in the low end of the spectrum builds high amounts of high load strength (the ability to lift something really heavy a few times).  Working in the mid-range of reps builds strength in the moderate range (lifting something not so heavy a whole bunch of times) and working in the high rep range builds strength and endurance (lifting something light or moderate a whole bunch of times without getting tired.)


Let us help you reach your goals!