Strain Tracking

Know exactly how hard to push. Every day.

Laso tracks your cardiovascular load throughout the day and tells you how much more you can handle based on how recovered you are. No guessing, no fixed plans. Just a daily target calibrated to your body right now.

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Strain score explained

Your strain score runs from 0 to 21 and measures cumulative cardiovascular load based on how much time you spend in each heart rate zone throughout the day.

Heart rate zones drive the score

Laso divides your heart rate into five zones based on your personal max heart rate. Time in higher zones contributes exponentially more strain than time in lower zones.

Zone 1 (50 to 60% max HR) — Light activity, minimal strain
Zone 2 (60 to 70%) — Easy aerobic, fat burning
Zone 3 (70 to 80%) — Moderate effort, tempo work
Zone 4 (80 to 90%) — Hard, threshold training
Zone 5 (90 to 100%) — All out, max effort

The scale is logarithmic

Strain does not increase linearly. Getting from 0 to 10 is relatively easy with normal daily activity and light exercise. Getting from 10 to 15 requires moderate training. Getting above 18 takes sustained high intensity effort.

0 to 9 — Light day

Walking, desk work, errands. Normal daily living.

10 to 14 — Moderate

A solid run, gym session, or active sports day.

15 to 18 — High

Intense training. Interval work, long endurance sessions.

18 to 21 — Maximal

Race day or extreme efforts. Rare and very demanding.

Recovery-adjusted targets

A strain score by itself is just a number. The real value is knowing what your target should be today, and that depends entirely on how recovered you are.

High recovery (67 to 100) — Push it

Your body is primed for adaptation. Laso sets a higher strain target, typically in the 14 to 18 range. This is when hard intervals, long runs, and heavy lifting sessions pay off the most. Training on high recovery days is how you actually get fitter.

Moderate recovery (34 to 66) — Stay controlled

You can train, but going all out would likely dig a deeper hole. Laso recommends a moderate strain target, usually between 10 and 14. Think steady state cardio, technique work, or a regular gym session without chasing personal records.

Low recovery (0 to 33) — Protect yourself

Your body needs more time. Laso drops the target below 10, recommending light activity like walking, stretching, or yoga. Pushing through a low recovery day does not build fitness. It delays recovery and increases injury risk.

What-if simulation

Preview the impact of a planned workout before you do it. Make smarter training decisions by seeing the trade-off in advance.

How it works

Select a workout type (running, cycling, strength, HIIT, and more) and an estimated duration. Laso uses your current strain, recovery, and historical response patterns to project the resulting strain increase and its estimated impact on tomorrow's recovery score.

When it is most useful

Imagine you are moderately recovered and debating between a 60 minute hard run today or saving it for tomorrow. The simulator shows you that the hard run today would push your strain to 17 and drop projected recovery to 38, while waiting until tomorrow (when recovery might be 72) would let you handle the same session and still wake up at 55. That is the kind of trade-off that changes training outcomes over weeks and months.

Built on your personal data

The projections are not generic estimates. They are based on how your body has historically responded to similar strain loads at similar recovery levels. The more data Laso has, the more accurate the simulation becomes. After about 30 days of training data, the projections are quite reliable.

Overtraining detection

Burnout does not happen suddenly. It builds gradually over days and weeks. Laso spots the pattern before you feel the symptoms.

Strain vs recovery balance

Laso watches the rolling ratio between how much strain you accumulate and how well you recover. When strain consistently outpaces recovery for several days, the imbalance triggers an alert before performance drops.

Biomarker trend analysis

Individual bad nights happen. Overtraining shows up as a multi-day trend: HRV drifting down, resting heart rate drifting up, sleep quality declining. Laso tracks these trends and alerts you when the pattern is consistent enough to be concerning.

Early warning alerts

When Laso detects an overtraining pattern forming, it recommends a specific recovery protocol: reduced strain targets, earlier bedtimes, and a projected timeline for when you should be back to baseline.

Personal, not generic

Some people overtrain at 5 hard sessions per week. Others can handle 7. Laso does not use a one-size-fits-all threshold. It learns your specific capacity and flags when you are exceeding your pattern, not a textbook guideline.

Strain tracking is part of a bigger picture

Your strain data connects to every other insight in Laso. Recovery fuels strain targets. Sleep fuels recovery. It all works together.

Recovery Score

Your daily readiness score determines your strain targets. High recovery unlocks higher targets. Low recovery scales everything back to protect you.

Sleep Coaching

Sleep is where recovery happens. After a high strain day, Laso adjusts your sleep recommendations to make sure you get the restorative rest you need.

Start training smarter tomorrow.

Connect your wearable and let Laso calculate your first strain target.

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