Gradient Biotech

Stress and activity

Extend autonomic analysis beyond the heart — add electrodermal activity (the sympathetic "stress" axis) and accelerometer-derived movement, and use motion to judge when ECG/HRV can be trusted.

Research question

What do skin-conductance responses and physical activity add to the autonomic picture, and how much of the HRV signal is contaminated by movement?

Who this is for

  • Stress, recovery, sleep, and naturalistic-physiology researchers
  • Wearable / digital health teams combining heart, electrodermal, and motion sensors
  • Anyone needing motion-aware quality control on wearable ECG/HRV

Data requirements

DataRequiredPurpose
EDA signal (CSV)For EDATonic/phasic decomposition and SCRs
Accelerometer (CSV: time + x/y/z or magnitude)For activity / motionENMO activity and motion burden
ECG waveformFor motion qualityPairing R-peaks against activity

Workflow

Upload EDA / ACC → Analyze EDA, Analyze activity → (ECG) Preprocess → Motion quality → Interpret

Step 1 — Electrodermal activity

Upload an EDA recording (choose EDA as the waveform modality) and run Analyze EDA. You get:

  • Skin conductance level (tonic, SCL)
  • Phasic skin conductance responses — count, rate, and amplitude
  • A clean-vs-tonic trace

Step 2 — Activity (accelerometer)

Upload an accelerometer CSV (choose ACC) and run Analyze activity: ENMO intensity, active vs sedentary burden, and an activity-over-time chart.

Step 3 — Motion quality (cross-modal)

On an ECG dataset, open Motion quality, pick a completed ACC run to pair, and click Check motion. The pipeline reports motion burden %, the % of beats recorded during movement, and the high-motion segments — so HRV and morphology can be caveated or filtered.

Step 4 — Interpret (optional)

Interpretation cites EDA, activity, and motion-quality metrics as Electrodermal, Activity / motion, and Motion quality modalities; high motion burden automatically adds an HRV-reliability caveat.

Expected outputs

  • EDA tonic/phasic metrics and SCRs
  • Activity intensity (ENMO) and sedentary/active burden
  • Motion burden and beats-in-motion for a paired ECG
  • Combined autonomic + motion context for interpretation

Example insight

Skin conductance responses cluster during the high-activity segment, and 24% of ECG beats fall in motion windows there — HRV from that segment should be interpreted with caution.

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