{"product_id":"neurometric-hrv-dfalpha1","title":"NeuroMetric HRV-DFalpha1","description":"\u003cdiv class=\"hero\"\u003e\n\u003cp class=\"hero-sub\"\u003eReal-time DFA α1 heart rate variability monitoring for precision endurance training. Works with any Bluetooth HR sensor. Measure your real time:\u003c\/p\u003e\n\u003cdiv class=\"hero-stats\"\u003e\n\u003ch4 class=\"stat\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"stat-value\"\u003e0.75   \u003c\/span\u003e\u003cspan class=\"stat-label\"\u003eAerobic Threshold    (VT1)\u003c\/span\u003e\n\u003c\/h4\u003e\n\u003ch4 class=\"stat\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"stat-value\"\u003e0.50   \u003c\/span\u003e\u003cspan class=\"stat-label\"\u003eAnaerobic Threshold    (VT2)\u003c\/span\u003e\n\u003c\/h4\u003e\n\u003ch4 class=\"stat\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"stat-value\"\u003e120s   \u003c\/span\u003e\u003cspan class=\"stat-label\"\u003eRolling Analysis Window\u003c\/span\u003e\n\u003c\/h4\u003e\n\u003ch4 class=\"stat\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"stat-value\"\u003eAny \u003c\/span\u003e\u003cspan class=\"stat-label\"\u003eBLE HR Sensor  *Chest Strap Preferred\u003c\/span\u003e\n\u003c\/h4\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003csection id=\"science\"\u003e\u003cspan class=\"section-tag\"\u003eThe Science\u003c\/span\u003e\n\u003ch2\u003eWhat is DFA α1 and why does it matter?\u003c\/h2\u003e\n\u003cp\u003eDFA α1 — Detrended Fluctuation Analysis alpha 1 — is a mathematical measure of the fractal complexity of your heartbeat pattern. Unlike traditional HRV metrics that measure the size of variability, DFA α1 measures the\u003cspan\u003e \u003c\/span\u003e\u003cem\u003estructure\u003c\/em\u003e\u003cspan\u003e \u003c\/span\u003eof variability — how correlated or random your heart's rhythm is from beat to beat.\u003c\/p\u003e\n\u003cp\u003eAt rest and low intensity, your heart beats in a complex, fractal-like pattern driven by parasympathetic (vagal) tone. As exercise intensity increases, the sympathetic nervous system takes over and this pattern breaks down — becoming simpler and more random. DFA α1 tracks this breakdown in real time, revealing two critical physiological thresholds.\u003c\/p\u003e\n\u003cdiv class=\"threshold-visual\"\u003e\n\u003ch3\u003eThe DFA α1 Intensity Spectrum\u003c\/h3\u003e\n\u003cp\u003eHow your α1 value maps to exercise intensity and autonomic state\u003c\/p\u003e\n\u003cdiv class=\"threshold-bar\"\u003e\n\u003cdiv class=\"zone zone-easy\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"zone-value\"\u003e\u0026gt; 1.0    \u003c\/span\u003e\u003cspan class=\"zone-label\"\u003eEASY \/ RELAXED PACE\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zone zone-fatmax\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"zone-value\"\u003e0.75–1.0   \u003c\/span\u003e\u003cspan class=\"zone-label\"\u003eFATMAX ZONE\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zone zone-med\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"zone-value\"\u003e0.5–0.75   \u003c\/span\u003e\u003cspan class=\"zone-label\"\u003eTHRESHOLD\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zone zone-max\" style=\"text-align: center;\"\u003e\n\u003cspan class=\"zone-value\"\u003e\u0026lt; 0.5   \u003c\/span\u003e\u003cspan class=\"zone-label\"\u003eANAEROBIC\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zone zone-max\"\u003e\u003cspan class=\"zone-label\"\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"threshold-markers\"\u003e\n\u003cspan\u003eRest \/ Recovery\u003c\/span\u003e\u003cspan class=\"marker-vt1\"\u003e← VT1 at α1 = 0.75 (Yellow line)\u003c\/span\u003e\u003cspan class=\"marker-vt2\"\u003eVT2 at α1 = 0.50 (Red line) →\u003c\/span\u003e\u003cspan\u003eMax Effort\u003c\/span\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"cards\"\u003e\n\u003cdiv class=\"card\"\u003e\n\u003cdiv class=\"card-icon icon-blue\"\u003e🧬\u003c\/div\u003e\n\u003ch3\u003eAerobic Threshold — VT1\u003c\/h3\u003e\n\u003cp\u003eWhen α1 drops below\u003cspan\u003e \u003c\/span\u003e\u003cspan class=\"pill pill-yellow\"\u003e0.75\u003c\/span\u003e, you have crossed VT1 — the first ventilatory and lactate threshold. This is the upper boundary of true Zone 2 training. Training below this point maximises fat oxidation, mitochondrial density, and aerobic base without accumulating systemic fatigue.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003cdiv class=\"card-icon icon-orange\"\u003e⚡\u003c\/div\u003e\n\u003ch3\u003eAnaerobic Threshold — VT2\u003c\/h3\u003e\n\u003cp\u003eWhen α1 drops below\u003cspan\u003e \u003c\/span\u003e\u003cspan class=\"pill pill-red\"\u003e0.50\u003c\/span\u003e, you have crossed VT2 — the anaerobic threshold. The heart's beat pattern is now essentially random, driven by acute demand. Only short efforts are sustainable here. This is the Norwegian double-threshold target zone.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003cdiv class=\"card-icon icon-green\"\u003e🎯\u003c\/div\u003e\n\u003ch3\u003eNon-invasive Threshold Testing\u003c\/h3\u003e\n\u003cp\u003ePreviously, identifying VT1 and VT2 required laboratory lactate testing. DFA α1 provides the same physiological thresholds in real time using only a chest strap — validated against Kubios gold-standard HRV analysis in multiple peer-reviewed studies.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003cdiv class=\"card-icon icon-cyan\"\u003e📡\u003c\/div\u003e\n\u003ch3\u003eAny Bluetooth HR Sensor\u003c\/h3\u003e\n\u003cp\u003eUnlike other apps locked to Polar devices, NeuroMetric HRV works with any standard Bluetooth Low Energy heart rate sensor — Garmin, Wahoo, cheap chest straps, and more — using the universal BLE Heart Rate Service protocol.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003csection id=\"reading\"\u003e\u003cspan class=\"section-tag\"\u003eReading the Display\u003c\/span\u003e\n\u003ch2\u003eUnderstanding what you see\u003c\/h2\u003e\n\u003cp\u003eThe app displays three key metrics in real time, updated every 20 seconds once 2 minutes of data are collected.\u003c\/p\u003e\n\u003cdiv class=\"reading-guide\"\u003e\n\u003cdiv class=\"reading-card rc-easy\"\u003e\n\u003cstrong\u003e\u003cspan class=\"rc-value\"\u003e\u0026gt; 1.0    \u003c\/span\u003e\u003c\/strong\u003e\u003cstrong\u003eEasy \/ Relaxed Pace\u003c\/strong\u003e\n\u003cdiv class=\"rc-desc\"\u003eDeep parasympathetic dominance. Recovery or very light warm-up. Well below aerobic threshold.\u003c\/div\u003e\n\u003cdiv class=\"rc-desc\"\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"reading-card rc-fatmax\"\u003e\n\u003cstrong\u003e\u003cspan class=\"rc-value\"\u003e0.75–1.0   \u003c\/span\u003eFatMax Zone\u003c\/strong\u003e\n\u003cdiv class=\"rc-desc\"\u003eOptimal aerobic training. Maximum fat oxidation. Sustainable for long efforts. Stay here for \u003cstrong\u003eZone 2.\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"rc-desc\"\u003e\n\u003cstrong\u003e\u003c\/strong\u003e\u003cbr\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"rc-desc\"\u003e\n\u003cstrong style=\"font-size: 0.875rem;\"\u003e\u003cspan class=\"rc-value\"\u003e0.5–0.75   \u003c\/span\u003e\u003c\/strong\u003e\u003cstrong style=\"font-size: 0.875rem;\"\u003eThreshold Zone\u003c\/strong\u003e\u003cstrong\u003e\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"reading-card rc-threshold\"\u003e\n\u003cdiv class=\"rc-desc\"\u003eBetween VT1 and VT2. Lactate accumulating. Norwegian double-threshold interval zone.\u003c\/div\u003e\n\u003cdiv class=\"rc-desc\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"reading-card rc-hard\"\u003e\n\u003cstrong\u003e\u003cspan class=\"rc-value\"\u003e\u0026lt; 0.5   \u003c\/span\u003eAnaerobic\u003c\/strong\u003e\n\u003cdiv class=\"rc-desc\"\u003eAbove VT2. High-intensity. Unsustainable beyond short intervals. Significant recovery cost.\u003c\/div\u003e\n\u003cdiv class=\"rc-desc\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"table-wrap\"\u003e\n\u003ctable class=\"metrics-table\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eMetric\u003c\/th\u003e\n\u003cth\u003eWhat it means\u003c\/th\u003e\n\u003cth\u003eNormal resting range\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eα1\u003c\/td\u003e\n\u003ctd\u003eDFA alpha1 — the primary training intensity metric. The green line on the graph. Updates every 20 seconds from a 2-minute rolling window.\u003c\/td\u003e\n\u003ctd\u003e1.0 – 1.8 at rest\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHR (bpm)\u003c\/td\u003e\n\u003ctd\u003eInstantaneous heart rate in beats per minute. Updated with each heartbeat notification from your sensor.\u003c\/td\u003e\n\u003ctd\u003e40 – 80 bpm at rest\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRMSSD\u003c\/td\u003e\n\u003ctd\u003eRoot mean square of successive RR differences. A time-domain HRV measure reflecting parasympathetic activity. Higher = more recovered.\u003c\/td\u003e\n\u003ctd\u003e25 – 80 ms at rest\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eArtifacts \/ Samples (%)\u003c\/td\u003e\n\u003ctd\u003eNumber of rejected RR intervals vs total samples in the 2-minute window. Below 5% is ideal. Above 20% reduces α1 reliability.\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; 5% ideal during exercise\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYellow line (graph)\u003c\/td\u003e\n\u003ctd\u003eFixed reference at α1 = 0.75 — your aerobic threshold (VT1). Keep your α1 trace above this for Zone 2 training.\u003c\/td\u003e\n\u003ctd\u003eα1 = 0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRed line (graph)\u003c\/td\u003e\n\u003ctd\u003eFixed reference at α1 = 0.50 — your anaerobic threshold (VT2). Crossing this marks high-intensity territory.\u003c\/td\u003e\n\u003ctd\u003eα1 = 0.50\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003csection id=\"guide\"\u003e\u003cspan class=\"section-tag\"\u003eUser Guide\u003c\/span\u003e\n\u003ch2\u003eGetting started step by step\u003c\/h2\u003e\n\u003cdiv class=\"app-steps\"\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003ePrepare your HR sensor\u003c\/h3\u003e\n\u003cp\u003eWet the electrode pads of your chest strap with water or electrode gel. Put it on and wait 30 seconds for a stable signal. Any BLE HR sensor with RR interval support works — chest straps give the most accurate RR data for DFA α1 calculation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003eOpen NeuroMetric HRV and grant permissions\u003c\/h3\u003e\n\u003cp\u003eOn first launch, the app asks for Bluetooth permissions. Tap\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eAllow\u003c\/strong\u003e. Without this permission the app cannot scan for or connect to your HR sensor. On Samsung devices you may also need to enable \"Nearby devices\" permission in Settings → Apps → NeuroMetric HRV → Permissions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003eScan and select your sensor\u003c\/h3\u003e\n\u003cp\u003eTap the three-dot menu (⋮) →\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eScan for HR sensors\u003c\/strong\u003e. A dialog appears listing all nearby BLE heart rate devices. Tap your sensor's name to connect. The status bar at the bottom shows\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eCONNECTED\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003ewhen successful.\u003c\/p\u003e\n\u003cdiv class=\"highlight\"\u003e\n\u003cp\u003e💡 After your first session, use\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eConnect last sensor\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003ein the menu to reconnect instantly without scanning.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003eWait for the first α1 reading\u003c\/h3\u003e\n\u003cp\u003eThe app needs a full 2-minute window of RR data before the first α1 value appears. During this time HR and RMSSD will update but α1 shows dashes. This is normal and scientifically required — a shorter window produces unreliable DFA calculations.\u003c\/p\u003e\n\u003cdiv class=\"code-block\"\u003eα1 appears after ~20 seconds of clean RR data\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv class=\"step-num\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003ch3\u003eMonitor your intensity in real time\u003c\/h3\u003e\n\u003cp\u003eWatch the green α1 trace on the graph. Your goal during aerobic base training is to keep the trace\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eabove the yellow 0.75 line\u003c\/strong\u003e. If α1 drops toward or below the yellow line, slow down immediately to return to the aerobic zone.\u003c\/p\u003e\n\u003cp\u003eDuring threshold intervals, target the zone\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003ebetween the yellow and red lines\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e(α1 = 0.50 to 0.75).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003eExport your session data\u003c\/h3\u003e\n\u003cp\u003eTap the three-dot menu →\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eExport Logs\u003c\/strong\u003e. This shares two files via your choice of app (WhatsApp, email, etc.):\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003err.log\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e— every RR interval with timestamp, for detailed HRV analysis in Kubios or other software.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003efeatures.csv\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e— timestamped α1, HR, RMSSD, artifact rate per calculation window — ideal for charting session progress.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"step\"\u003e\n\u003cdiv\u003e\n\u003ch3\u003eLabel your session\u003c\/h3\u003e\n\u003cp\u003eTap\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eRename Session\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eto tag the log files with a meaningful name — client name, date, workout type. This makes it easy to identify sessions when reviewing exported data later.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003csection id=\"ramp\"\u003e\u003cspan class=\"section-tag\"\u003eProtocol\u003c\/span\u003e\n\u003ch2\u003eThe DFA α1 Ramp Test — finding your personal thresholds\u003c\/h2\u003e\n\u003cp\u003eRun this test once every 4–8 weeks to track fitness changes. Your VT1 and VT2 heart rates will shift upward as fitness improves — meaning you can work harder at the same autonomic cost.\u003c\/p\u003e\n\u003cdiv class=\"ramp-grid\"\u003e\n\u003cdiv class=\"ramp-phase\"\u003e\n\u003cspan class=\"phase-label\"\u003ePhase 1 · 0–12 min\u003c\/span\u003e\n\u003ch3\u003eWarm-up\u003c\/h3\u003e\n\u003cp\u003eWalk or very easy jog. Ensure α1 is stable and well above 1.0 before beginning the ramp. Rushing this phase produces unreliable threshold detection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"ramp-phase\"\u003e\n\u003cspan class=\"phase-label\"\u003ePhase 2 · 12–40 min\u003c\/span\u003e\n\u003ch3\u003eGradual ramp\u003c\/h3\u003e\n\u003cp\u003eIncrease pace or power very slowly — approximately every 3 minutes. The α1 value needs 2 minutes to reflect each intensity change. Rushing the ramp misses the threshold crossings.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"ramp-phase\"\u003e\n\u003cspan class=\"phase-label\"\u003eDetection · Watch the graph\u003c\/span\u003e\n\u003ch3\u003eVT1 identification\u003c\/h3\u003e\n\u003cp\u003eNote the HR and pace\/power the moment the green α1 trace crosses below the\u003cspan\u003e \u003c\/span\u003e\u003cspan class=\"pill pill-yellow\"\u003eyellow 0.75 line\u003c\/span\u003e. This is your personal aerobic threshold — your Zone 2 ceiling.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"ramp-phase\"\u003e\n\u003cspan class=\"phase-label\"\u003eDetection · Continue ramp\u003c\/span\u003e\n\u003ch3\u003eVT2 identification\u003c\/h3\u003e\n\u003cp\u003eContinue increasing intensity. Note the HR and pace\/power when α1 crosses below the\u003cspan\u003e \u003c\/span\u003e\u003cspan class=\"pill pill-red\"\u003ered 0.50 line\u003c\/span\u003e. This is your anaerobic threshold — your threshold interval target zone upper limit.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"highlight\"\u003e\n\u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eArtifact rate must stay below 5–10% during the ramp for reliable threshold detection. If artifacts spike above 20%, re-wet your strap and ensure a firm, flat contact with skin.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003csection id=\"specs\"\u003e\u003cspan class=\"section-tag\"\u003eTechnical Specifications\u003c\/span\u003e\n\u003ch2\u003eHow the algorithm works\u003c\/h2\u003e\n\u003cp\u003eNeuroMetric HRV implements the validated DFA α1 calculation method used by Kubios HRV Premium, with the smoothness priors detrending method.\u003c\/p\u003e\n\u003cdiv class=\"table-wrap\"\u003e\n\u003ctable class=\"metrics-table\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eAnalysis window\u003c\/td\u003e\n\u003ctd\u003e120 seconds (2 minutes)\u003c\/td\u003e\n\u003ctd\u003eRolling window, slides with each new RR interval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecalculation period\u003c\/td\u003e\n\u003ctd\u003e20 seconds (default)\u003c\/td\u003e\n\u003ctd\u003eConfigurable down to 5 seconds minimum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDetrending method\u003c\/td\u003e\n\u003ctd\u003eSmoothness priors (λ = 500)\u003c\/td\u003e\n\u003ctd\u003eMatches Kubios Premium — validated by Bruce Rogers et al.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eArtifact rejection\u003c\/td\u003e\n\u003ctd\u003eAuto mode (5% @HR\u0026gt;95, 25% @HR\u0026lt;80)\u003c\/td\u003e\n\u003ctd\u003eRejects RR intervals changing by more than threshold %\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBLE protocol\u003c\/td\u003e\n\u003ctd\u003eStandard GATT HR Service (UUID 0x180D)\u003c\/td\u003e\n\u003ctd\u003eWorks with any compliant BLE HR sensor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRR resolution\u003c\/td\u003e\n\u003ctd\u003e1\/1024 second (~1ms)\u003c\/td\u003e\n\u003ctd\u003eStandard BLE HR Measurement characteristic format\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLog output\u003c\/td\u003e\n\u003ctd\u003err.log + features.csv\u003c\/td\u003e\n\u003ctd\u003eCompatible with Kubios, HRV4Training, and spreadsheet analysis\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003csection id=\"help\"\u003e\u003cspan class=\"section-tag\"\u003eTroubleshooting\u003c\/span\u003e\n\u003ch2\u003eCommon issues and solutions\u003c\/h2\u003e\n\u003cdiv class=\"cards\"\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eHigh artifact rate (\u0026gt;20%)\u003c\/h3\u003e\n\u003cp\u003eRe-wet the chest strap electrodes. Ensure firm, even contact with skin. Wait 60 seconds for signal to stabilise before starting. Cotton t-shirts can cause signal dropout — bare skin contact is best.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eα1 not appearing\u003c\/h3\u003e\n\u003cp\u003eNormal for the first 2 minutes. If it never appears, check artifact rate — if above 50% the data quality is too poor for DFA calculation. Try repositioning the strap.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eApp cannot find sensor\u003c\/h3\u003e\n\u003cp\u003eEnsure Bluetooth is on. Tap Scan for HR sensors in the menu. Make sure no other app (Polar Beat, Garmin Connect) is connected to the sensor simultaneously — BLE allows only one connection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eα1 seems too high or too low\u003c\/h3\u003e\n\u003cp\u003eAt rest, α1 of 1.2–1.6 is normal. During exercise it should decline. Values above 1.8 or below 0.3 may indicate artifact contamination. Check your artifact rate percentage.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eReference lines disappearing\u003c\/h3\u003e\n\u003cp\u003eThe yellow and red reference lines extend as the session scrolls. If they appear to vanish, they will reappear with the next α1 calculation update. This is a known display refresh behavior.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"card\"\u003e\n\u003ch3\u003eApp disconnects during workout\u003c\/h3\u003e\n\u003cp\u003eEnable \"Keep screen on\" to prevent Android from pausing the app. Avoid switching to other apps mid-session. Samsung devices may require disabling battery optimization for NeuroMetric HRV.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cfooter\u003e\n\u003cp\u003e\u003cstrong\u003eNeuroMetric HRV\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e— DFA α1 Real-Time Training Monitor\u003c\/p\u003e\n\u003cp\u003eDeveloped by\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/proneurolight.com\/\"\u003eProNeuroLIGHT\u003c\/a\u003e\u003cspan\u003e \u003c\/span\u003e· Contact:\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"mailto:drjoe@proneurolight.com\"\u003edrjoe@proneurolight.com\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003eDFA α1 methodology validated by Rogers et al. (2021) Front. Physiol. · Algorithm matches Kubios HRV Premium via smoothness priors detrending (λ=500)\u003c\/p\u003e\n\u003c\/footer\u003e","brand":"ProNeuroLIGHT","offers":[{"title":"Default Title","offer_id":49231054766332,"sku":null,"price":3.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0665\/9506\/2012\/files\/WhatsAppImage2026-06-27at2.32.21PM_1_6b31c32f-1a67-40d9-8219-4566df705873.jpg?v=1782603807","url":"https:\/\/www.proneurolight.com\/products\/neurometric-hrv-dfalpha1","provider":"ProNeuroLIGHT","version":"1.0","type":"link"}