APP PURPOSE & CORE CONCEPT
Pulstep is a heart rate-regulating running app that uses real-time biometric feedback and haptic stimulation to help users maintain optimal heart rate zones for various fitness goals such as fat-burning, cardiovascular improvement, and recovery. It leverages existing wearable technology (e.g., Apple Watch) to personalize feedback without requiring additional devices.
WHY?
1. Running is the most accessible form of exercise
- Among all physical activities, running is the easiest to start. It requires no gym, no special gear, and no cost. Since COVID-19, the number of casual runners and amateur marathoners has significantly increased.
2. Heart rate zones are key to effective training
- Scientific studies show that training within the right heart rate zone can maximize fat burning and improve endurance. Especially for those aiming to lose weight, staying in the ideal heart rate zone is crucial.
3. Current apps rely on sight and sound
- Most fitness apps use visual displays or audio cues to guide users. But during a run, checking a screen or listening to audio can be distracting and break focus.
4. Pulstep delivers real-time tactile feedback
- Pulstep uses real-time haptic (vibration) feedback via smartwatches. It detects the user’s heart rate and sends a vibration signal if the user needs to adjust their pace.
RESEARCH SUMMARY
Haptic & Heart Rate Relationship
“We present a wrist-worn mobile heart rate regulator – ambienBeat – which provides closed-loop biofeedback via tactile stimulus based on users’ heartbeat rate (HR). […] Results from the user study show that the tactile stimulation was effective in guiding user’s HR to resonate with ambienBeat to either calm or boost the heart rate using minimal cognitive load.”
Key Experimental Findings
Heart rate increased most rapidly with 120 bpm tactile stimulation.
- When participants received tactile feedback at 120 beats per minute (bpm), their heart rate showed the fastest increase, with an average rise of +3.9% compared to the baseline condition.
Heart rate decreased fastest with 60 bpm tactile stimulation (calming effect).
- Tactile feedback at 60 bpm produced a noticeable calming effect, leading to a significantly faster reduction in heart rate than auditory or visual stimuli.
Tactile feedback caused the least cognitive disruption.
- Among the modalities tested, tactile stimulation was the least distracting, making it highly effective for use during multitasking or active tasks, unlike sound or screen-based prompts.
Tactile feedback was the most preferred modality by users.
- In post-experiment surveys, participants ranked tactile stimulation as the most preferred feedback method, citing comfort, subtlety, and non-intrusiveness.
Tactile stimulation significantly improved stress resilience (SDNN).
- The SDNN (Standard Deviation of Normal-to-Normal intervals), a key physiological marker for stress, increased the most under tactile feedback, indicating improved psychological relaxation and autonomic balance.
Reference:
Choi, K. Y., & Ishii, H. (2020). ambienBeat: Wrist-worn mobile tactile biofeedback for heart rate rhythmic regulation. In Proceedings of the 14th International Conference on Tangible, Embedded, and Embodied Interaction (TEI ’20) (pp. 205–214). Association for Computing Machinery. https://doi.org/10.1145/3374920.3374938
Heart Rate & Exercise Efficiency
“The artificial increase in walking speed significantly affected heart rate and energy expenditure. Fast walking led to a consistent and statistically significant rise in heart rate, as well as a sharp increase in calorie consumption compared to slow walking.
Key Experimental Findings
Heart Rate Responds Strongly to Speed Changes
- In fast walking conditions, heart rate increased from 70.65 bpm (resting) to 172.35 bpm (Stage 4).
- The increase in heart rate was significantly greater in the fast walking group at each intensity level.
Calorie Burn Rises Sharply With Heart Rate
- Fast walking resulted in a 60.9% higher calorie burn compared to slow walking:
Stage 4 slow walking: 97.96 kcal/kg
Stage 4 fast walking: 157.65 kcal/kg
Oxygen Consumption Increased With Heart Rate
- VO₂ (oxygen consumption) showed a linear increase with walking speed:
Stage 4 slow: 19.87 ml/kg/min
Stage 4 fast: 27.69 ml/kg/min
Perceived Exertion Matched Heart Rate Response
- Participants reported higher RPE (Rating of Perceived Exertion) during fast walking:
Stage 4 RPE: Slow = 11.00, Fast = 16.25
Reference
Lee, H. I. (2020). The Effect of Artificial Change of Velocity in Walking Exercise on Energy Consumption, Oxygen Consumption, Blood Pressure, Heart Rate, Awareness of Exercise and Respiratory Exchange Ratio. Master’s Thesis, Konkuk University, Department of Physical Education.
APP FLOW & FEATURE STRUCTURE
Step 1: Initial Launch & Permissions
Upon first launch:
1. The app requests permission to access: Health data & Heart rate sensors on the connected wearable device.
Two options:
Accept: Permission saved, user continues to app
Deny: App closes, permission requested again at next launch
Step 2: Age Input
1. Purpose: Calculate the user's maximum heart rate using the formula 220 - Age
Input method:
Numeric scroll input (1–99)
Compatible with Apple Watch Digital Crown or touch scroll
After selection, user presses "Next"
Step 3: Function Selection
Scroll-based interface for selecting exercise mode:
1. Recovery (30–50% HRmax)
2. Light Aerobic (50–60%)
3. Fat Burn (60–70%)
4. Cardiovascular Endurance (70–80%)
5. Anaerobic / HIIT (80–90%)
Vibration Logic:
Below range: Vibration speeds up
Above range: Vibration slows down
Example (Age 32):
Max HR = 188 bpm
Max HR = 188 bpm
Recovery: 56–94 bpm
Light Aerobic: 94–113 bpm
Fat Burn: 113–132 bpm
Cardio: 132–150 bpm
Anaerobic: 150–169 bpm
Step 4: Confirmation & Risk Warning
Display message:
Warns that max HR is approximate and individual health varies
Advises to stop use and consult a doctor if discomfort occurs
Disclaims responsibility for adverse health outcomes
Options:
Agree: Proceed to session
Decline: Exit app
Step 5: Function Execution & Live Display
App starts monitoring HR via device
Feedback loop executes:
If HR < min: haptic pattern matches midpoint bpm to encourage increase
If HR > max: haptic pattern matches midpoint bpm to encourage decrease
When HR aligns with feedback bpm: vibration stops
Display elements:
Selected mode name
Min HR / Max HR
Live user HR
Session timer
Buttons:
View heart rate graph
Stop function (returns to function selection)
Step 6: Critical HR Response - Mandatory Feature
If user HR exceeds 90–100% of max:
Immediate alert and vibration warning
Session auto-switches to Recovery Mode (30–50%)
Haptic feedback recalibrated to guide HR back into safe zone
DESIGN DIRECTION & UX PRINCIPLE
1. Consistent with original logic: algorithmic fidelity ensured
2. Minimal UI with intuitive haptic-led interaction
3. Transparent health data access
4. Adaptive, real-time safety and feedback mechanisms
DEMO VIDEO
