I Trained One Side HEAVY vs LIGHT For 60 Days (Bad Idea)
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Date: 2025-09-28
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Comments and reviews: 20
jeremy_ethier
The conclusion seems to be train for how you intend to use your body, if you have a sport or job where high endurance over long periods of time is important lower weight more reps makes sense, but if your training to move single heavy objects hulk style then high weight low reps seems the way to go. And if its just for looks it doesn't seem to matter but the lower weight might have an advantage to avoiding injury which has the additional long term affect of not interrupting your training routine to recover from those injuries. Perhaps a hybrid approach to balance the benefits of both You might never get the explosive strength of perpetually training heavy but mixing in a day a week to do higher weights for lower reps might still give you the numbers gain just a bit slower, while preserving joints and getting the endurance gains Just my thoughts. I haven't lifted in almost 20 years and am personally very early in what will be a long recovery process from medical. stuff, I am still having to use a frame to even do body weight squats (which I can do at all now, vs a couple months ago so gains) but it is interesting to see where it has gone since then! Great video.
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The conclusion seems to be train for how you intend to use your body, if you have a sport or job where high endurance over long periods of time is important lower weight more reps makes sense, but if your training to move single heavy objects hulk style then high weight low reps seems the way to go. And if its just for looks it doesn't seem to matter but the lower weight might have an advantage to avoiding injury which has the additional long term affect of not interrupting your training routine to recover from those injuries. Perhaps a hybrid approach to balance the benefits of both You might never get the explosive strength of perpetually training heavy but mixing in a day a week to do higher weights for lower reps might still give you the numbers gain just a bit slower, while preserving joints and getting the endurance gains Just my thoughts. I haven't lifted in almost 20 years and am personally very early in what will be a long recovery process from medical. stuff, I am still having to use a frame to even do body weight squats (which I can do at all now, vs a couple months ago so gains) but it is interesting to see where it has gone since then! Great video.
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tonymccake3057
8: 13: 00 With small weight/high reps all that extra volume in the early, easy reps of every set are junk volume; they are barely working your muscles at all so you cannot fairly compare the volume totals.
Conversely lifting heavy in very low rep ranges for isolation exercises is an issue, because you are not lifting all the volume you could have, unless you do additional drop sets, (which in turn negates the less time taken advantage.
The optimum range is 8 - 15 reps for isolation exercises as you concluded at the end; it is the best compromise between strength and endurance, unless you have a particular goal for either.
Of course going outside of these periodically is a useful shock to the muscles because they will adapt to a repeated routine in any range.
This is an interesting experiment but the most beneficial exercises for strength and growth are compound ones. Compound exercises also fully engage your core and are intrinsically more stable than a Bulgarian squat for example, which may be why you got hit with back twinges when returning to deadlift.
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8: 13: 00 With small weight/high reps all that extra volume in the early, easy reps of every set are junk volume; they are barely working your muscles at all so you cannot fairly compare the volume totals.
Conversely lifting heavy in very low rep ranges for isolation exercises is an issue, because you are not lifting all the volume you could have, unless you do additional drop sets, (which in turn negates the less time taken advantage.
The optimum range is 8 - 15 reps for isolation exercises as you concluded at the end; it is the best compromise between strength and endurance, unless you have a particular goal for either.
Of course going outside of these periodically is a useful shock to the muscles because they will adapt to a repeated routine in any range.
This is an interesting experiment but the most beneficial exercises for strength and growth are compound ones. Compound exercises also fully engage your core and are intrinsically more stable than a Bulgarian squat for example, which may be why you got hit with back twinges when returning to deadlift.
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josephwilson8391
You may be curious as to why increased muscle gain occurs with higher repetitions and lighter weights. This is primarily because individuals are executing the exercises correctly. In contrast, when using heavier weights, many people often do not perform the exercises as intended. Lighter weights often carry a negative perception, as society tends to emphasize the necessity of lifting extremely heavy. Furthermore, opting for heavier weights can be a quicker solution for those who prefer a less rigorous approach. Personally, I believe that performing more repetitions constitutes a greater overall effort. This perspective comes from someone who has a tendency to be somewhat lazy and prefers to lift heavier weights to avoid exerting more effort. However, I do not believe that lifting heavier necessarily correlates with a greater work ethic. In fact, I feel that individuals who lift lighter weights and complete more repetitions are putting in more effort than I do.
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You may be curious as to why increased muscle gain occurs with higher repetitions and lighter weights. This is primarily because individuals are executing the exercises correctly. In contrast, when using heavier weights, many people often do not perform the exercises as intended. Lighter weights often carry a negative perception, as society tends to emphasize the necessity of lifting extremely heavy. Furthermore, opting for heavier weights can be a quicker solution for those who prefer a less rigorous approach. Personally, I believe that performing more repetitions constitutes a greater overall effort. This perspective comes from someone who has a tendency to be somewhat lazy and prefers to lift heavier weights to avoid exerting more effort. However, I do not believe that lifting heavier necessarily correlates with a greater work ethic. In fact, I feel that individuals who lift lighter weights and complete more repetitions are putting in more effort than I do.
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Shawnquenneville
Here's my 6 month workout plan. 4 mesocycles 6 weeks each. Start light
Day 1
Shoulder press
Bench press
Dips assisted
Deficit push ups
Dumb bell flys (or cable)
Incline Dumbbell bench press
Hanging leg raises
Day2 leg day
Bulgarian split squats BW 3 sets of 10
Bss 10lb dumb bells 3 sets 10
Bss 25lb dumb bells 3 sets of 10
Hack squats 1 set of 12
Heavy squat 1 set of 8.
Calf raises 1 mega set to get a pump
Day 3
Skull crushers with barbell (just bar)
Tricep over head extensions
Lawn mower rows
Curls
Chin ups assisted
Shoulder rows (pull ups)
Rest day
Week 1 5 sets of 12
Week 2 15
Week 3 18
Week 4 20
Week 5 18
Week 6 15
Week 7 rest
Redo it. Add 10% on most of the exercises and you'll be happy.
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Here's my 6 month workout plan. 4 mesocycles 6 weeks each. Start light
Day 1
Shoulder press
Bench press
Dips assisted
Deficit push ups
Dumb bell flys (or cable)
Incline Dumbbell bench press
Hanging leg raises
Day2 leg day
Bulgarian split squats BW 3 sets of 10
Bss 10lb dumb bells 3 sets 10
Bss 25lb dumb bells 3 sets of 10
Hack squats 1 set of 12
Heavy squat 1 set of 8.
Calf raises 1 mega set to get a pump
Day 3
Skull crushers with barbell (just bar)
Tricep over head extensions
Lawn mower rows
Curls
Chin ups assisted
Shoulder rows (pull ups)
Rest day
Week 1 5 sets of 12
Week 2 15
Week 3 18
Week 4 20
Week 5 18
Week 6 15
Week 7 rest
Redo it. Add 10% on most of the exercises and you'll be happy.
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soilbydesign9303
I think it's pretty well understood now that 30, 12 or 6 reps to failure will give you the same amount of muscle growth (hypertrophy. The key is getting past that 85% of your single rep max (RM) weight so that you activate hiigh levels of mechanical tension in your muscle. I think the focus should be on strength which comes about through high weight/ low reps moreso than through extended reps with lighter weights. This is because strength is created not just by hypertrophy but other factors that only occur when that high level mechanical tension occurs. If you want a lean, tight look without bulk, with all the strength of a weightlifter, go hard at 85% for 3-4 reps. If what you want is bulk, then move to 6-20 reps at 60% of your RM.
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I think it's pretty well understood now that 30, 12 or 6 reps to failure will give you the same amount of muscle growth (hypertrophy. The key is getting past that 85% of your single rep max (RM) weight so that you activate hiigh levels of mechanical tension in your muscle. I think the focus should be on strength which comes about through high weight/ low reps moreso than through extended reps with lighter weights. This is because strength is created not just by hypertrophy but other factors that only occur when that high level mechanical tension occurs. If you want a lean, tight look without bulk, with all the strength of a weightlifter, go hard at 85% for 3-4 reps. If what you want is bulk, then move to 6-20 reps at 60% of your RM.
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ss-manoa4534
It might be interesting to compare with eccentric training, where you control the weight as your muscles lengthen. I cheat by using my whole body or jerking or other means to raise the weight and then slowly lowering the weight with one or both limbs. I try to work up to the maximum weight I can handle for each of 3-5 sets of 3 reps. I generally need to lower the weight for each set as I don’t rest much between sets.
Perhaps I would have better results with a different approach, but I have gained strength in the last few years even though I only work out 2-4 hours a month and am over 70 years old. A sports nutritionist suggested this method, and it seems to work well enough for me with limited time to spend in the gym.
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It might be interesting to compare with eccentric training, where you control the weight as your muscles lengthen. I cheat by using my whole body or jerking or other means to raise the weight and then slowly lowering the weight with one or both limbs. I try to work up to the maximum weight I can handle for each of 3-5 sets of 3 reps. I generally need to lower the weight for each set as I don’t rest much between sets.
Perhaps I would have better results with a different approach, but I have gained strength in the last few years even though I only work out 2-4 hours a month and am over 70 years old. A sports nutritionist suggested this method, and it seems to work well enough for me with limited time to spend in the gym.
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TheBloodyNights
I was expecting the lighter side to win on most size. Since the vast majority of body builders go lighter weights for a decent amount of reps. Which is why a lot of body builders tend to look really big, but are not that strong. I also know when you only go heavy, strength increases, and endurance decreases, and vice versa.
Personally I value strength a bit more. But with stuff like that I think 5-7 sets of around 5 reps at heavier weight is needed. 455lb deadlift for 1 set of 5 is easy. doing it for 5 sets though it gets tough quick! For me anyways. But uhhh throwing in some amraps at lighter weight isn't bad either occasionally.
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I was expecting the lighter side to win on most size. Since the vast majority of body builders go lighter weights for a decent amount of reps. Which is why a lot of body builders tend to look really big, but are not that strong. I also know when you only go heavy, strength increases, and endurance decreases, and vice versa.
Personally I value strength a bit more. But with stuff like that I think 5-7 sets of around 5 reps at heavier weight is needed. 455lb deadlift for 1 set of 5 is easy. doing it for 5 sets though it gets tough quick! For me anyways. But uhhh throwing in some amraps at lighter weight isn't bad either occasionally.
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LordB-dg8ks
Not 100% sure but this all comes down to the 3 types of muscle and how your body automatically balances things. By doing lower weights for longer, you put more effort into the muscles meant for stamina while the other side of your body grew the thicker muscles meant for short bursts that don't have any stamina. That was why despite almost no difference in appearance, there was such a difference in performance. You basically built one half of your body for long distance running while the other is made for sprinting.
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Not 100% sure but this all comes down to the 3 types of muscle and how your body automatically balances things. By doing lower weights for longer, you put more effort into the muscles meant for stamina while the other side of your body grew the thicker muscles meant for short bursts that don't have any stamina. That was why despite almost no difference in appearance, there was such a difference in performance. You basically built one half of your body for long distance running while the other is made for sprinting.
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alex86fire
I thought this was already known. As I have already heard it from at least 2 other trainers. The only thing that matters for muscle growth is training to failure. Problem is, as Jeremy also stated, it is harder to train to failure with the light weights. If you can do the switch, maybe start with heavy and finish with light (in the same set) for max failure and muscle growth
Also, I didn't see him training his core at all. Training your core could fix some of that imbalance he experienced.
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I thought this was already known. As I have already heard it from at least 2 other trainers. The only thing that matters for muscle growth is training to failure. Problem is, as Jeremy also stated, it is harder to train to failure with the light weights. If you can do the switch, maybe start with heavy and finish with light (in the same set) for max failure and muscle growth
Also, I didn't see him training his core at all. Training your core could fix some of that imbalance he experienced.
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InkyDustMan
More Volume = More Mass
Lighter weights for higher reps, for the same sets, basically evens out the volume equation to be more balanced between reps and weight, leading to higher volume, but less strength focus.
And more muscle doesn't inherently mean higher overall performance stats, since strength and endurance are generally separate skills.
So. variety or mid-range for a balanced build, or if you don't mind going all in on one, just do what you want and what makes you happy.
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More Volume = More Mass
Lighter weights for higher reps, for the same sets, basically evens out the volume equation to be more balanced between reps and weight, leading to higher volume, but less strength focus.
And more muscle doesn't inherently mean higher overall performance stats, since strength and endurance are generally separate skills.
So. variety or mid-range for a balanced build, or if you don't mind going all in on one, just do what you want and what makes you happy.
reply
mjkag1127
The way I used to train was to use a weight where failure was in the range of 7-12 reps. If I couldn't hit 7, weight was too high, if I could do more than 12 then it was not enough weight. Drop-set for the last.
Over time number of reps you do on an exercise start increasing, once you get to 12 reps, increase weight to bring reps back to 7-8, and that is the new workout weight.
Over time, weight keeps going up, but my main goal was strength, not size.
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The way I used to train was to use a weight where failure was in the range of 7-12 reps. If I couldn't hit 7, weight was too high, if I could do more than 12 then it was not enough weight. Drop-set for the last.
Over time number of reps you do on an exercise start increasing, once you get to 12 reps, increase weight to bring reps back to 7-8, and that is the new workout weight.
Over time, weight keeps going up, but my main goal was strength, not size.
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kuburog2267
when i used to lift i would always go heavy 3-5 reps for 5 sets increase weight each set. do whole body workouts only lifting every other day or 3 days a week at min. on sore days i would do the same increase with weight per set but would do lighter weights for more reps 8-10 for 5 sets. seemed to stabilize the imbalance in str vs endur. would also always warm up with 100 pushups/sit ups and 5 minutes of jump rope. give it a shot and see how it works out
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when i used to lift i would always go heavy 3-5 reps for 5 sets increase weight each set. do whole body workouts only lifting every other day or 3 days a week at min. on sore days i would do the same increase with weight per set but would do lighter weights for more reps 8-10 for 5 sets. seemed to stabilize the imbalance in str vs endur. would also always warm up with 100 pushups/sit ups and 5 minutes of jump rope. give it a shot and see how it works out
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jp2135744
Borge Fergerli convincingly showed that higher reps cause some kind of muscular swelling a short time making you look bigger. High volumes most likely have a similar affect. So I perform a low to moderate rep and volume program and do high reps about 2 weeks before I want to look my biggest for something. My guess is that if you waited 10 days instead of 3 days to take measurement the high rep side would have been smaller due to decreased fluid retnetion
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Borge Fergerli convincingly showed that higher reps cause some kind of muscular swelling a short time making you look bigger. High volumes most likely have a similar affect. So I perform a low to moderate rep and volume program and do high reps about 2 weeks before I want to look my biggest for something. My guess is that if you waited 10 days instead of 3 days to take measurement the high rep side would have been smaller due to decreased fluid retnetion
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jeremy_ethier
I'm 60 so injury prevention is paramount.
My younger year heavy training left me with middle back injuries that still limit my back and chest development. Thankfully I'm 6'3 and have natural shoulders and triceps to look 'big'.
Now that I'm training for mobility, longevity and aesthetics, injury prevention is the overarching priority.
I still work to failure via 'effective reps' but I'm not risking injury.
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I'm 60 so injury prevention is paramount.
My younger year heavy training left me with middle back injuries that still limit my back and chest development. Thankfully I'm 6'3 and have natural shoulders and triceps to look 'big'.
Now that I'm training for mobility, longevity and aesthetics, injury prevention is the overarching priority.
I still work to failure via 'effective reps' but I'm not risking injury.
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jeremy_ethier
Brilliant video, very informative and I love that it is scientific / experimental. I have been team light weight for years and endurance definitely characterised one of my strengths and still does I believe. Still training in a variety of ways and will be adding some heavier weights in there this year and nextstill training with light to mid weights for the majority of the time though (not forgetting my love of cardio.
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Brilliant video, very informative and I love that it is scientific / experimental. I have been team light weight for years and endurance definitely characterised one of my strengths and still does I believe. Still training in a variety of ways and will be adding some heavier weights in there this year and nextstill training with light to mid weights for the majority of the time though (not forgetting my love of cardio.
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cassandradowns7662
The back strain told me all I needed to know. As someone who struggles with chronic lower back pain, been in PT for months, I’ve been scared to lift heavier with fear it’ll make my back worse. I worked with my DPT who is also a personal trainer to ensure my form is correct and ideal for my body type, so this video is giving me more confidence that I can progress with heavier weight at lower reps. Thank you!
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The back strain told me all I needed to know. As someone who struggles with chronic lower back pain, been in PT for months, I’ve been scared to lift heavier with fear it’ll make my back worse. I worked with my DPT who is also a personal trainer to ensure my form is correct and ideal for my body type, so this video is giving me more confidence that I can progress with heavier weight at lower reps. Thank you!
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ashram12
The lower weighs / higher reps is safer. I have a genetic predisposition for heart disease, and cardiologists have warned me to avoid heavy weights because that increases the stress on the heart. So while I would like to be stronger (I’m not looking to be a body builder, but being able to do a pull-up would be nice, I have to do the lower intensity exercises that won’t strain my heart.
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The lower weighs / higher reps is safer. I have a genetic predisposition for heart disease, and cardiologists have warned me to avoid heavy weights because that increases the stress on the heart. So while I would like to be stronger (I’m not looking to be a body builder, but being able to do a pull-up would be nice, I have to do the lower intensity exercises that won’t strain my heart.
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lechkenassh9008
heavy weights build bulk the low weights is for tone and definition! but the person who does samller weights can do alot more after! right now I can't curl a 50lb weight 1 arm right now. but when fall fishing is done. that weight will feel like nothing to me! well fish weigh between 5-9 lbs and when you move them more that 1000 times a day! you build stength fast in 3 months!
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heavy weights build bulk the low weights is for tone and definition! but the person who does samller weights can do alot more after! right now I can't curl a 50lb weight 1 arm right now. but when fall fishing is done. that weight will feel like nothing to me! well fish weigh between 5-9 lbs and when you move them more that 1000 times a day! you build stength fast in 3 months!
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Dylan-le1qd
In conclusion, low-weight high reps builds endurance and high-weight low reps builds strength. So the key to high strength and endurance is to combine them!
Thanks so much Jeremy - this is a video everyone must watch, finally I have clear understanding between callisthenics & body builders. They have built two completely different types of strengths. Again Many Thanks!
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In conclusion, low-weight high reps builds endurance and high-weight low reps builds strength. So the key to high strength and endurance is to combine them!
Thanks so much Jeremy - this is a video everyone must watch, finally I have clear understanding between callisthenics & body builders. They have built two completely different types of strengths. Again Many Thanks!
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jeremy_ethier
thank you for showing us the value of balance with training. I was taught to always experiment on yourself first so that you can see what happens when you train a certain way. this was extreme and it was cool to see. I feel bad that you hurt yourself, I probably would've done the same thing, knowing full well what the results would be. Thanks again for sharing
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thank you for showing us the value of balance with training. I was taught to always experiment on yourself first so that you can see what happens when you train a certain way. this was extreme and it was cool to see. I feel bad that you hurt yourself, I probably would've done the same thing, knowing full well what the results would be. Thanks again for sharing
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