Pedometers and Activity Level Assessment

Pedometer Technology

• Spring Lever Pedometers
  • Relies on a spring mechanism.
  • Affordable.
  • Worn on the waist or placed in a pocket.
  • The spring triggers with movement.
• Piezoelectric Pedometers
  • 'Piezo' means pressure or push.
  • Contains a crystal that detects steps in multiple directions.
• Accelerometer Based Pedometers
  • Found in devices like Apple Watch and Garmin wristwatches.
  • Tracks acceleration, measuring movement across multiple axes (up, down, front, back, side to side, and diagonally).

Research on Spring Lever Pedometers

• A 2012 research article indicated that spring lever pedometers (e.g., Sportline, Yomx DigiWalker SW series):
  • Accurate for steady, moderate-pace walking.
  • May miss steps at lower speeds, a common issue for older adults.
• Treadmill test research study findings:
  • At 50 steps per minute, error was 56%.
  • At 66 steps per minute, error was 40%.
  • At 80 steps per minute, error decreased.
  • At a comfortable walking speed, the Sportline closely matched the actual step count.
• A 2017 treadmill research study found that the Sportline closely matched actual step count in college students and even outperformed some advanced models under consistent walking conditions.

Mileage Calculation Inaccuracy

• Calculating mileage from step count can be inaccurate due to varying stride lengths.
• Yarmax is considered accurate (even the gold standard in some research) because it requires manual stride length setting.

Overcoming Mileage Inaccuracy

• Yarmax instructs users to walk 10 steps and measure the distance to set stride length.

Research on Piezoelectric Pedometers (Yarmax Series)

• A 2017 study indicated:
  • Error rate of less than 3% at regular or brisk speeds, especially when worn on the waist or in a pocket.
  • Reliable for most daily activities.
  • Slight accuracy drop (4.59%) at slow walking speeds.
• Study Details
  • Purpose: To assess step count accuracy of pedometers worn on different body parts, compared to an accelerometer, and to determine preferred wearing locations.
  • Participants: 63 healthy adults.
  • Procedure: Participants wore seven pedometers and one accelerometer and walked 20 meters at slow, normal, preferred, and fast speeds. Steps were counted, and participants were asked about preferred wearing locations.
• Results
  • More accurate at the front waist and inside pockets.
  • More accurate than an accelerometer (more expensive).
  • Preferred Wearing Locations: 45 out of 63 participants preferred a pocket location (25 in the right front pocket, 20 in the left front pocket).

Research on Apple Watch

• A 2018 study conducted on a treadmill showed:
  • Slow speed: overestimated steps by 2.6%.
  • Moderate speed: overestimated steps by 0.9%.
  • Brisk walking pace: overestimated steps by 1.6%.
  • Consistently underestimated jogging by 3.4%.

Research on Garmin Vivofit

• A free-living study (participants went about daily life, not on a treadmill) found that Garmin overestimated step count by an average of 1,433 steps.
• Reason: Arm movements during daily activities (e.g., talking, gesturing) are counted as steps.

Research on Fitbit and Smart Health

• A 2017 study (conducted on a treadmill) found:
  • Fitbit undercounted steps by 55 on average at slow walking speeds.

Accuracy Comparison: Waist-Mounted vs. Wrist-Based Monitors

• Waist-mounted monitors capture steps more accurately than wrist-based monitors because they follow the hips' up-and-down motion.

Considerations for Pedometer Use

• For individuals with health conditions, use the most accurate device, preferably recommended/provided by a doctor.
• For general activity tracking, using the same device consistently allows comparison to oneself, even if not perfectly accurate.
• Even if a device is consistently off by a certain amount (e.g., 1,000 steps), it can still show activity trends (high vs. low activity days).

Device Recommendations

• For slow walkers, a waist-mounted spring lever or piezoelectric option may be suitable.
• Ankle-mounted pedometers (spring lever or piezoelectric) may be appropriate for long bike rides or runs (not in circles).
• Watches and phones lack standardization and require further research.

Direct Observation for Assessing Physical Activity

• Involves watching someone and noting their activity level.

Recording Activity Levels

• Physical activity is assessed by coding the physical activity level or body position of a target student at predetermined intervals.
• Five categories:
  1. Lying down: Posture code, recorded only if the student is not expending energy at a rate greater than an ordinary amount.
  2. Sitting: Posture code, recorded only if the student is not expending energy at a rate greater than an ordinary amount.
  3. Standing: Posture code, recorded only if the student is not expending energy at a rate greater than an ordinary amount.
  4. Walking: There is transfer of weight from one foot to the other. Includes pivoting (e.g., in basketball) and walking at any pace up to a moderate level. Walking fast is coded as vigorous.
  5. Vigorous: The student is expending more energy than during ordinary walking. Includes running, jogging, skipping, walking while struggling with a heavy load, and getting up from lying down (if repeated continuously).
• When a student is in transition from one category to another, code the higher category (e.g., partially lying down and partially sitting up is coded as sitting).