Ever notice that dumbbell curls feel easy on one arm and surprisingly hard on the other, at the exact same weight? You're not imagining it — left/right strength imbalances are extremely common, to varying degrees, in almost everyone.
Why imbalances happen
Hand and foot dominance, old injuries, and everyday asymmetric habits (always carrying a bag on the same shoulder, favoring one arm for certain tasks) all contribute. Barbell exercises, where both sides move together, tend to hide this. Dumbbell and other unilateral exercises expose it directly — one side simply can't keep up with the reps the other side handles easily.
What happens if you ignore it
In bilateral exercises, the stronger side often unconsciously compensates for the weaker one, meaning the weaker side gets even less stimulus over time — and the gap widens rather than closes. Beyond the visual asymmetry, this can lead to form breakdown and uneven stress on your joints.
The catch is that if you log both sides together as one number, this gap barely shows up in your data. What you end up recording is essentially "whatever the stronger side could do," leaving the weaker side's real capability invisible.
What separate tracking reveals
Logging each side independently lets you see:
- How big the current gap actually is (in both weight and reps)
- Whether that gap is closing or widening over time
- How much progress the weaker side is genuinely making — its own estimated 1RM, its own volume
Once the gap is a number instead of a feeling, you can make deliberate decisions — like giving the weaker side an extra set, or setting your working weight based on what the weaker side can actually handle — instead of guessing.
How to put this into practice
Start with dumbbell or other unilateral exercises where each side moves independently, and log them separately. The simplest approach at first is to base your working weight on the weaker side. As you get more comfortable, you can try giving the weaker side extra sets, or paying closer attention to its range of motion and form.
If the gap is large, or a new imbalance shows up suddenly, it may be more than just a strength difference — it could be worth checking with a professional rather than pushing through it.
Related articles
- What Is Progressive Overload? The Basic Principle Behind Every Gain
- What Is Training Volume? How to Calculate It and Beat Plateaus
LiFTY lets you turn on "Track left/right separately" for any exercise, logging sets, targets, and personal bests independently for each side — with the gap charted over time. No account needed to start right away.
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