Profile & Characteristics
Personal health profile. Static or rarely-changing characteristics that provide context for other health metrics.
Biological Sex
Definition
A user characteristic stored in HealthKit used for normative calculations and reference range interpretation.
Why It Matters
Many health reference ranges are sex-specific: - VO₂ max classifications - Body fat percentage norms - Hemoglobin levels - Heart rate patterns - Metabolic calculations
Without this information, health metrics cannot be properly contextualized against population norms.
How It's Obtained
User-entered in the Apple Health profile. This is not measured by any device—it must be manually set by the user.
Use Cases
- Personalized ranges - Display sex-appropriate reference values
- Fitness calculations - Adjust cardio fitness interpretations
- Body composition - Context for body fat percentage
- Risk assessments - Sex-specific health risk calculations
Important Notes
- This characteristic is used for physiological reference ranges
- It does not affect how data is collected, only how it's interpreted
- Users can update this setting at any time in Apple Health
References
Blood Type
Definition
ABO blood group and Rh factor (e.g., A+, B-, O+, AB-).
Why It Matters
Blood type is critical in several medical contexts: - Transfusion medicine - Matching blood types prevents severe reactions - Pregnancy - Rh incompatibility can affect fetal health - Emergency care - Quick access to blood type information - Organ donation - Compatibility matching - Surgery preparation - Blood availability planning
How It's Obtained
User-entered in Apple Health. This should be validated from official medical records, as incorrect blood type information could be dangerous in emergencies.
Reference Values
| Blood Type | Population Frequency (approximate) |
|---|---|
| O+ | ~37% |
| A+ | ~36% |
| B+ | ~8% |
| AB+ | ~3% |
| O- | ~7% |
| A- | ~6% |
| B- | ~1% |
| AB- | ~1% |
Frequencies vary by ethnic background and geographic region.
Use Cases
- Emergency preparedness - Quick reference in medical emergencies
- Medical ID - Part of essential health information
- Family health records - Tracking inherited traits
Important Notes
- Only enter your blood type if you know it from verified medical testing
- Incorrect blood type information could be harmful
- Blood type can be determined through simple medical testing
References
Date of Birth (Age)
Definition
The user's birth date, used to calculate age for risk interpretation and normative ranges.
Why It Matters
Most physiologic reference ranges shift with age: - VO₂ max - Naturally declines with age - Heart rate variability - Generally decreases with age - Resting heart rate - Reference ranges vary by age - Blood pressure - Risk thresholds may differ - Body composition - Norms change across the lifespan - Sleep patterns - Requirements and architecture shift
Age is essential for meaningful interpretation of nearly all health metrics.
How It's Obtained
User-entered in the Apple Health profile.
Use Cases
- Age-adjusted norms - Compare metrics to appropriate peer groups
- Risk calculations - Age-appropriate health assessments
- Fitness classifications - VO₂ max categories by age
- Trend interpretation - Distinguish age-related changes from other factors
Important Notes
- Age affects how almost every health metric should be interpreted
- Reference ranges in medical literature are typically stratified by age
- Accurate age entry is important for meaningful health insights
References
Fitzpatrick Skin Type
Definition
A classification system (Types I–VI) describing how skin responds to ultraviolet (UV) light exposure.
Why It Matters
Skin type affects: - Sunburn risk - Lower types burn more easily - Vitamin D synthesis - Darker skin requires more sun exposure - UV exposure recommendations - Personalized sun protection guidance - Skin cancer risk - Varies by skin type - Cosmetic procedures - Laser and light treatments
The Fitzpatrick Scale
| Type | Description | Sun Response |
|---|---|---|
| I | Very fair, freckles, red/blonde hair | Always burns, never tans |
| II | Fair skin, light hair | Burns easily, tans minimally |
| III | Medium skin | Burns moderately, tans gradually |
| IV | Olive skin | Burns minimally, tans well |
| V | Brown skin | Rarely burns, tans darkly |
| VI | Dark brown/black skin | Never burns, deeply pigmented |
How It's Obtained
User-entered in Apple Health based on self-assessment.
Use Cases
- UV exposure alerts - Personalized sun protection reminders
- Outdoor activity planning - Appropriate exposure limits
- Dermatology preparation - Relevant for skin treatments
- Health education - Understanding personal sun sensitivity
Important Notes
- This is a simplified classification; real skin response varies
- Skin type doesn't change but sun sensitivity can be affected by medications
- All skin types can experience sun damage; protection is always recommended
References
Wheelchair Use
Definition
A user characteristic indicating whether the person uses a wheelchair for mobility.
Why It Matters
Wheelchair use fundamentally changes which activity metrics are appropriate: - Push count replaces step count as the primary movement metric - Wheelchair distance replaces walking/running distance - Activity goals are calibrated differently - Workout types may focus on wheelchair-specific activities
How It's Obtained
User-entered in Apple Health settings. When enabled, Apple Watch adjusts its activity tracking algorithms.
Impact on Metrics
| Standard Metric | Wheelchair Equivalent |
|---|---|
| Step Count | Push Count |
| Walking Distance | Wheelchair Distance |
| Stand Hours | Roll Hours |
| Walking Workouts | Wheelchair Workouts |
Use Cases
- Appropriate activity tracking - Meaningful movement metrics
- Personalized goals - Achievable activity targets
- Workout recognition - Wheelchair-specific exercise detection
- Health monitoring - Relevant fitness indicators
Important Notes
- Apple Watch includes wheelchair workout types when this is enabled
- Activity rings adjust to reflect wheelchair-appropriate goals
- Both outdoor and indoor wheelchair activities are supported