Heart Rate Monitoring for the Chester Step Test: H10 vs Verity Sense vs Pulse Oximeter

Heart rate measurement is central to the Chester Step Test.

The Chester Step Test is a progressive submaximal test used to estimate aerobic capacity. As the stepping rate increases, the participant’s exercise heart rate is used alongside perceived exertion to determine progression and ultimately contribute to the prediction of aerobic fitness.

That means the heart-rate monitor is not simply an accessory.

The quality of the heart-rate measurement can affect the quality of the assessment.

For many years, chest-strap heart-rate monitors have been the standard practical solution. More recently, however, upper-arm optical monitors such as the Polar Verity Sense have become increasingly attractive, particularly in occupational-health settings where privacy, hygiene, ease of fitting and throughput all matter.

At the same time, some organisations use wrist watches or finger pulse oximeters to obtain heart rate during step testing.

So which method is most appropriate?

This guide looks at:

• electrical chest straps such as the Polar H10
• upper-arm optical monitors such as the Polar Verity Sense
• wrist-worn optical heart-rate monitors
• finger pulse oximeters
• manual pulse measurement
• clinical ECG

It also explains the evidence behind each method and what this means specifically for professional Chester Step Testing.

Why heart-rate measurement matters in the Chester Step Test

The Chester Step Test was developed as a practical submaximal assessment of aerobic capacity.

In the original validation study, 68 participants completed the Chester Step Test on two occasions. Participants stepped at progressively increasing rates, beginning at 15 steps per minute and increasing every two minutes. Heart rate was measured continuously using a Polar heart-rate monitor, while heart rate and rating of perceived exertion were recorded at the end of each stage.

The test was stopped when the participant reached the appropriate heart-rate or perceived-exertion criterion, or completed the final stage. The predicted aerobic-capacity result showed a strong relationship with directly measured VO₂max.

Later descriptions of the Chester Step Test in occupational medicine similarly specify continuous heart-rate monitoring, with exercise heart rate recorded at defined stages and used in the estimation of aerobic capacity.

The important point is:

Heart rate is part of the measurement methodology, not merely something displayed to the assessor.

If a monitor produces a delayed, unstable or incorrect value, it can potentially affect the quality of the data entered into the assessment.

For that reason, the correct question is not:

Can this device display heart rate?

It is:

Can this device measure exercise heart rate accurately, consistently and quickly enough for professional Chester Step Testing?

How heart-rate monitors actually measure heart rate

Most practical exercise devices rely on one of two technologies.

Electrical heart-rate measurement

Chest straps such as the Polar H10 detect electrical cardiac signals using electrodes positioned against the chest.

They identify the electrical event associated with each heartbeat and derive heart rate from the interval between beats.

This is why good chest straps tend to perform particularly well when exercise intensity changes quickly.

It is important to distinguish this from a clinical diagnostic ECG. A chest strap is not a multi-lead diagnostic ECG system, but its heart-rate measurement is derived from electrical cardiac activity rather than peripheral blood-flow changes.

Optical heart-rate measurement

Upper-arm monitors, wrist watches and pulse oximeters usually rely on photoplethysmography, or PPG.

PPG uses light to detect changes in blood volume in the tissue as blood pulses through the circulation.

Modern PPG devices can measure exercise heart rate accurately in some settings, but performance varies by device, wearing position, activity and movement.

However, optical measurement has a fundamental challenge during exercise:

motion can interfere with the optical signal.

Movement of the sensor relative to the skin, changes in skin deformation, changes in perfusion, repetitive movement and ambient conditions can all influence PPG readings. Research on wearable optical sensors has consistently identified movement as an important source of error during physical activity.

The location of the sensor also matters.

An optical sensor tightly secured to the upper arm may behave differently from one placed on a moving wrist or finger.

1. Chest-strap heart-rate monitors

Example: Polar H10

For professional exercise heart-rate monitoring, electrical chest straps remain the strongest practical benchmark.

The Polar H10 is one of the most extensively studied examples.

A 2022 validation study compared the H10 against ECG during resting conditions and an incremental cycling test. Heart-rate measurements showed very strong agreement with ECG, with only minimal heart-rate bias across exercise intensities.

A separate study examining wearables during tactical-style exercise compared several devices directly with ECG. The H10 demonstrated strong agreement across steady-state rucking, maximal-effort rucking, cycling and circuit exercise, with mean absolute percentage error between approximately 1.3% and 3.4%.

Advantages of a chest strap

Strong exercise accuracy

Electrical measurement is less vulnerable to many of the motion artefacts that affect optical sensors.

Rapid response

A chest strap can respond quickly as heart rate changes during progressive exercise.

Established evidence

The technology has a substantial validation history against ECG.

Strong Chester Step Test precedent

Polar heart-rate monitors were used in the original Chester Step Test validation research, and continuous Polar monitoring has also been used in subsequent workplace research involving the CST.

Practical disadvantages

In real occupational-health environments, chest straps are not perfect.

Potential problems include:

• fitting the strap beneath clothing
• privacy and dignity concerns
• awkwardness for participants or technicians
• inconsistent positioning
• inadequate electrode contact
• discomfort
• additional preparation time
• cleaning between participants
• damaged or dried-out electrode areas
• occasional signal dropout

These are not trivial considerations when a service may be assessing large numbers of employees.

What about chest hair?

Chest straps generally do not require routine chest shaving to obtain a heart-rate signal.

Correct strap tension, electrode moisture and appropriate placement are normally more relevant.

An organisation should avoid making shaving part of routine procedure unless there is a specific technical or clinical justification.

Overall view

A well-validated electrical chest strap such as the Polar H10 remains the best-supported practical reference option for Chester Step Test heart-rate monitoring.

Where fitting is practical, it has the clearest direct validation base against ECG among commonly used wearable options.

2. Upper-arm optical heart-rate monitoring

Example: Polar Verity Sense

This is where the question becomes more interesting.

The Polar Verity Sense is an optical PPG monitor normally worn around the upper arm.

Unlike a chest strap, it does not need to be positioned around the torso. That creates obvious advantages for occupational testing.

More importantly, the evidence base is now strong enough that it should not simply be dismissed because it is optical.

What does the research show?

In a 2023 study of trail running, the Polar Verity Sense met the investigators’ predefined validity and reliability thresholds across the full exercise session. The researchers concluded that the Verity Sense was valid and reliable during trail running.

A study in tactical populations compared the Verity device, Polar H10 and other wearables directly against ECG during several exercise modes. The Verity showed strong agreement during steady-state rucking, maximal-effort rucking and cycling, although performance was less favourable during highly dynamic Tabata circuit exercise.

A 2024 study examining four consumer optical sensors across laboratory and free-living activities found high overall validity. Across devices and activities, mean absolute percentage errors ranged from 2.2% to 4.7%, with the Polar Verity Sense among the upper-arm devices evaluated against medical-grade ECG.

A 2025 validation study examining the Verity Sense across multiple activities found particularly strong performance when worn on the upper arm. Compared with the reference device, the upper-arm Verity Sense showed minimal systematic bias, a mean absolute percentage error of around 1.35% and very high agreement across the activities examined.

Another 2025 study compared Verity Sense with Polar H10 during high-intensity interval exercise in adolescents. Overall mean absolute percentage error was 2.8%, although agreement weakened somewhat at higher heart rates.

The Verity Sense has also been validated in swimming environments, further supporting its ability to obtain useful heart-rate data across demanding exercise settings.

Why upper-arm placement can work well

Upper-arm placement has some mechanical advantages.

The wrist experiences considerable movement and repeated flexion during exercise.

The upper arm generally provides a larger, more stable contact area and the sensor can be held firmly against the skin.

Research comparing arm-worn and wrist-worn optical monitoring supports the idea that measurement location materially affects accuracy. In the 2025 multi-activity validation study, the Verity Sense on the upper arm substantially outperformed the wrist-worn device in consistency across activities.

That is particularly relevant to step testing.

The legs and trunk are repeatedly moving, but the upper arm can remain comparatively stable.

Practical advantages in occupational health

This is arguably where the Verity Sense has its strongest case.

An upper-arm monitor can offer:

• rapid fitting
• minimal clothing adjustment
• improved participant privacy
• less awkward physical positioning
• straightforward cleaning
• less dependence on electrode contact
• potentially greater participant acceptance
• faster movement between assessments

For occupational-health technicians conducting repeated assessments, these benefits may materially improve workflow.

But there is an important scientific caveat

This deserves to be explicit.

We have not identified a published study directly validating the Polar Verity Sense specifically during the Chester Step Test.

The existing evidence supports accurate heart-rate measurement across several exercise conditions, particularly when the device is worn on the upper arm.

That is useful supportive evidence, but it is not Chester Step Test-specific validation.

It is not the same as proving that:

Polar H10 and Verity Sense will always produce identical CST or CST2 outcomes.

The Chester Step Test uses heart rate within a specific progressive protocol.

A direct CST comparison would ideally require participants to wear both devices simultaneously while undertaking the same Chester Step Test, followed by analysis of:

• beat-to-beat or stage heart-rate agreement
• lag during workload changes
• anomalous readings
• stage-end heart rates
• test termination decisions
• resulting estimated VO₂max
• repeatability

Until such a study is performed, the scientifically correct description is:

The Verity Sense is well validated for exercise heart-rate measurement and represents a credible practical alternative, but CST-specific interchangeability has not yet been directly established.

Overall view

The Polar Verity Sense is a credible alternative to a chest strap for professional exercise heart-rate monitoring, especially where privacy, fitting, hygiene or workflow make chest straps difficult.

For Chester Step Testing specifically, however, its use should be supported by the wider exercise-validation evidence rather than described as directly CST-validated.

3. Finger pulse oximeters

Finger pulse oximeters are common in occupational-health and clinical environments.

Because they display a pulse rate, it can seem logical to use that number as the Chester Step Test heart rate.

There are several reasons to be cautious.

What a pulse oximeter measures

A pulse oximeter is primarily designed to estimate arterial oxygen saturation.

It also derives a pulse rate from the pulsatile optical signal.

That is not the same measurement principle as detecting electrical cardiac activity with a chest strap.

Under stable conditions, pulse rate and electrical heart rate will often match closely.

Exercise is less stable.

Motion artefact

Motion has long been recognised as a source of pulse-oximeter error.

Experimental studies have shown that movement can produce invalid readings, loss of data and reduced accuracy.

Exercise adds several challenges:

• finger movement
• probe movement
• sweating
• vibration
• changing peripheral blood flow
• reduced peripheral perfusion
• signal averaging
• delay while the device determines a stable pulse

What happens during exercise?

A study comparing pulse-oximeter pulse rate with simultaneous ECG during incremental treadmill and cycle exercise found good overall correlation but significant underestimation at heart rates above approximately 155 bpm. The authors concluded that using pulse oximeters as heart-rate monitors during strenuous exercise was questionable.

Another exercise study found that finger pulse-oximeter performance could be affected by exercise and altered perfusion, with sensor location materially influencing accuracy.

This should not be interpreted as saying that every modern pulse oximeter is inaccurate.

Technology has improved substantially.

The important principle is:

Pulse oximeter performance is device-specific, sensor-specific and vulnerable to movement.

You cannot assume that because a pulse oximeter gives an accurate resting pulse, it will provide an equally reliable exercise heart rate.

Why this matters during the Chester Step Test

The Chester Step Test involves continuous stepping.

If the assessor needs to stabilise the participant’s finger, wait for the pulse signal to settle or interpret a fluctuating reading during the final seconds of a stage, the measurement process becomes less straightforward.

A device may also display a smoothed or slightly delayed pulse rate rather than the instantaneous exercise heart rate the assessor expects.

That becomes relevant when heart rate contributes to stage progression and the estimated aerobic-capacity result.

Pulse oximetry can still have a role

A pulse oximeter may be appropriate when oxygen saturation is itself clinically required.

For example, exercise testing in respiratory populations may legitimately include SpO₂ measurement.

But that is a different use case from selecting the best device specifically to measure heart rate during a Chester Step Test.

Overall view

We would not choose a finger pulse oximeter as the preferred primary heart-rate monitor for routine Chester Step Testing where a validated chest strap or well-validated upper-arm monitor is available.

That is a different statement from saying pulse oximeters are unsuitable for clinical practice generally.

Their principal purpose and measurement characteristics simply make them less attractive for this particular task.

4. Wrist-worn optical heart-rate monitors

Modern sports watches have improved enormously.

Some provide excellent heart-rate readings during many types of exercise.

But wrist PPG has particular limitations.

The wrist is a mechanically challenging site because the sensor moves with the hand and arm.

Research on wearable optical sensors has shown that repetitive motion can create false or missing beats and can even cause an optical sensor to lock onto movement frequency rather than the true cardiovascular signal.

More recent work continues to show substantial variation in wrist-device accuracy depending on device and exercise type.

The tactical study is particularly instructive.

The chest straps and upper-arm Verity generally demonstrated the strongest agreement with ECG, whereas the two wrist devices showed more variable performance.

Likewise, the 2025 multi-activity study found greater variability with wrist-worn monitoring than with the upper-arm Verity Sense.

Does that mean a Garmin or Apple Watch cannot be used?

No.

It means that:

Professional assessment should not treat all wrist watches as equivalent merely because they display heart rate.

Accuracy is dependent on:

• the specific device
• fit
• wrist position
• exercise mode
• intensity
• movement pattern
• individual characteristics

For recreational exercise that may be acceptable.

For an occupational test where the result can inform formal fitness decisions, a more purpose-specific sensor is easier to defend.

Overall view

A high-quality wrist device may provide useful heart-rate data, but wrist optical monitoring would not currently be our first choice for formal Chester Step Testing.

5. Manual pulse measurement

Manual pulse measurement requires no electronic equipment.

The assessor identifies a radial or carotid pulse, counts beats over a defined period and converts the count into beats per minute.

It is simple, but there are obvious limitations during exercise.

For example, if heart rate is counted for 10 seconds and multiplied by six:

one missed beat = six beats per minute error.

There is also the problem of recovery.

If measurement begins after stepping stops, heart rate may already be falling.

The process can therefore produce both counting error and timing error.

Overall view

Manual pulse measurement is useful as a backup or cross-check, but continuous electronic monitoring is preferable for professional Chester Step Testing.

6. Clinical ECG

Electrocardiography remains the reference method for measuring electrical cardiac activity.

For research validation, ECG is extremely useful because consumer devices can be compared against it.

But routine Chester Step Testing is not a diagnostic exercise ECG.

Using a clinical ECG system would add:

• equipment
• electrodes
• setup time
• clinical expertise
• interpretation requirements
• cost

without normally improving the practical purpose of a routine occupational CST enough to justify that complexity.

Overall view

ECG is the scientific reference method, but it is unnecessary for routine Chester Step Test administration unless there is a separate clinical reason for cardiac monitoring.

Heart-rate monitoring methods compared

Polar H10 vs Polar Verity Sense for Chester Step Testing

For many organisations, this is the practical decision.

Polar H10

Strengths

• electrical signal
• extensively validated
• excellent agreement with ECG
• rapid response
• established professional exercise use
• strong historical fit with Chester Step Test methodology

Weaknesses

• requires chest fitting
• potential privacy/dignity concerns
• slower to fit
• needs appropriate skin contact
• cleaning between participants
• potential participant discomfort

Polar Verity Sense

Strengths

• easy upper-arm fitting
• less intrusive
• strong published exercise-validation evidence
• easier occupational workflow
• good participant acceptance
• no chest access required

Weaknesses

• optical rather than electrical
• potentially more vulnerable to movement/signal artefact
• CST-specific validation not yet identified
• exact interchangeability with H10 for CST outcomes has not been demonstrated

Practical interpretation

If your priority is the strongest existing measurement evidence, choose the H10.

If your priority includes high-throughput occupational usability, privacy and ease of fitting, while still requiring a device with a strong exercise-validation base, the Verity Sense has a compelling case.

That does not mean one should casually declare them identical.

It means the decision can legitimately take both measurement science and operational reality into account.

Why occupational-health services may prefer an upper-arm device

In a physiology laboratory, putting on a chest strap is straightforward.

A workplace medical programme is different.

An occupational-health technician may assess many employees in one day, potentially in mobile or temporary testing environments.

Participants may be wearing work clothing.

The technician and participant may be different sexes.

Some participants may simply dislike exposing the torso or positioning a chest strap.

The most scientifically accurate system becomes less useful if:

• it is frequently fitted incorrectly
• staff avoid using it correctly
• participants resist it
• it significantly slows the assessment
• hygiene procedures are inconsistent

This is why device choice should consider:

validity + reliability + usability + consistency.

A well-validated upper-arm optical monitor fitted correctly on every participant may be operationally preferable to a theoretically superior chest strap that is repeatedly fitted poorly.

That is an implementation judgement rather than a claim that optical measurement is inherently superior.

Hygiene: chest strap vs upper-arm sensor

Hygiene is another frequent concern.

Any reusable device that contacts the body should be cleaned according to the manufacturer’s instructions and local infection-control procedures.

A chest strap typically has a larger area in contact with the body and can absorb sweat.

An upper-arm sensor has a smaller and more accessible contact area, although the fabric armband itself still requires appropriate cleaning.

The advantage is therefore not that an armband is automatically hygienic.

It is that it may be easier to build a fast and repeatable cleaning process around it.

Organisations should document their cleaning procedure regardless of device.

Does skin colour affect optical heart-rate monitors?

This is an important question with PPG technology.

Optical sensing depends on light interacting with tissue, and researchers have investigated whether skin pigmentation, tattoos and other characteristics affect measurements.

The wider evidence suggests that optical device accuracy can vary according to device design, conditions and participant characteristics.

Recent research continues to examine factors such as skin tone and tattoos in devices including the Verity Sense.

This is another reason organisations should avoid assuming that every PPG device performs identically.

It also reinforces the value of selecting devices with independent validation across diverse participants and activities.

What if the heart-rate reading looks wrong?

No heart-rate monitor is infallible.

The assessor should not blindly accept an obviously implausible reading.

For example, if a participant’s heart rate has progressed:

105 → 118 → 132 bpm

and the next reading suddenly shows:

72 bpm

while the participant is still stepping at a higher workload, the value should be questioned.

Similarly:

195 bpm

appearing suddenly in a comfortable participant whose previous heart rate was 120 bpm may represent artefact rather than a real physiological response.

Check the following

Device position

Has the strap or armband moved?

Contact

Is the sensor firmly positioned?

Chest strap electrodes

Are they sufficiently moist and in contact with the skin?

Optical sensor

Is it fitted tightly enough without being excessively tight?

Signal stability

Has the reading been stable or is it fluctuating rapidly?

Participant response

Does the displayed heart rate broadly make sense alongside workload and perceived exertion?

Symptoms

Does the participant have any concerning signs or symptoms?

If there is any clinical concern, safety takes priority over obtaining a test result.

Heart rate should not be considered in isolation

The Chester Step Test incorporates rating of perceived exertion as well as heart rate.

Descriptions of the test specify progression and termination using both exercise heart rate and Borg RPE.

That provides an important second piece of information.

If the monitor displays a surprisingly low heart rate but the participant reports very high exertion, the assessor should not simply assume the participant can safely continue because the device says so.

Similarly, an unexpected physiological response should prompt clinical judgement.

Wearable technology informs the assessment. It does not replace competent test administration.

Should organisations use the same device every time?

Where possible, yes.

For longitudinal assessment, consistency is important.

If an employee is tested annually, it is preferable to standardise:

• monitor type
• sensor position
• fitting method
• assessment protocol
• step height
• software methodology
• stage measurement timing

Changing from one measurement technology to another introduces another variable.

That does not mean equipment can never be changed.

It means a service should document the change and understand that small differences between devices may contribute to differences between assessments.

This is particularly relevant where results sit close to an occupational fitness threshold.

Should a heart-rate monitor itself determine pass or fail?

No.

A monitor measures heart rate.

It does not define the occupational standard.

The test protocol, interpretation method and employer’s fitness requirements should determine how the result is used.

This distinction is especially important in firefighter and other safety-critical testing.

A device may be entirely suitable for measuring heart rate while the overall fitness decision still requires an appropriately governed testing process.

Our current recommendation

Based on the available evidence, our practical hierarchy for professional Chester Step Testing is:

1. Validated electrical chest strap

A device such as the Polar H10 remains the strongest practical benchmark where fitting is straightforward.

2. Well-validated upper-arm optical monitor

The Polar Verity Sense has a substantial and growing evidence base and is a credible alternative where chest straps create practical problems.

3. Wrist optical device

Potentially useful, but more dependent on the exact device and activity.

4. Finger pulse oximeter as primary heart-rate monitor

Not our preferred method for CST heart-rate measurement during active stepping.

5. Manual pulse

Useful as a backup or plausibility check.

Can the Polar Verity Sense reasonably replace the H10 for occupational Chester Step Testing?

The answer needs to be precise.

There is sufficient evidence to take the Verity Sense seriously as an accurate exercise heart-rate monitor. Multiple studies show strong agreement with reference measurements across different activities.

There are genuine operational advantages to upper-arm measurement in occupational health.

But:

we have not identified direct published CST-specific validation demonstrating that Verity Sense and H10 produce interchangeable Chester Step Test outcomes.

Therefore the strongest evidence-based position is:

A Polar Verity Sense can reasonably be considered a credible alternative for exercise heart-rate monitoring where its operational advantages are important, but organisations should not claim that it has been specifically validated as interchangeable with a Polar H10 for the Chester Step Test unless direct CST validation is available.

This position reflects the current evidence without dismissing modern optical technology or overstating CST-specific validation.

The study that would answer the question properly

There is an obvious opportunity for further research.

Participants could undertake the Chester Step Test while wearing:

Polar H10 + Polar Verity Sense simultaneously.

Researchers could compare:

• second-by-second heart rate
• stage-end heart rate
• mean absolute error
• mean absolute percentage error
• agreement using Bland-Altman analysis
• measurement lag
• abnormal readings
• test termination stage
• predicted VO₂max
• resulting fitness classification

A second test could assess repeatability.

This would answer the question that occupational-health teams actually need answered:

Does changing the heart-rate sensor materially change the Chester Step Test result?

That would be more useful for CST users than another general wearable validation study.

Frequently asked questions

What is the best heart-rate monitor for the Chester Step Test?

A validated electrical chest strap such as the Polar H10 currently has the strongest combination of exercise accuracy and scientific validation.

For organisations where chest fitting is impractical, a well-validated upper-arm optical monitor such as the Polar Verity Sense is a credible alternative.

Can I use the Polar Verity Sense for the Chester Step Test?

The Verity Sense has strong validation evidence for heart-rate measurement across multiple exercise settings.

However, we have not found a published study directly validating the device during the Chester Step Test itself.

Its use should therefore be described as supported by broader exercise-validation evidence rather than directly CST-validated.

Is the Polar Verity Sense as accurate as the Polar H10?

It can agree very closely with the H10 or ECG during many activities, and some recent studies report very low error when the Verity Sense is worn on the upper arm.

However, the devices use different technologies.

The H10 detects electrical cardiac signals.

The Verity Sense uses optical PPG.

Their performance should therefore not be assumed to be identical under every exercise condition.

Can I use a pulse oximeter to measure heart rate during the Chester Step Test?

It can display pulse rate, but that does not make it our preferred primary heart-rate monitoring method during active exercise.

Finger optical measurements can be affected by movement, perfusion and probe stability, and older exercise validation work demonstrated discrepancies compared with ECG during higher-intensity exercise.

Is a finger pulse oximeter inaccurate?

Not necessarily.

Many modern pulse oximeters provide excellent clinical measurements when used appropriately.

The issue is specifically whether finger pulse rate is the best method for continuous or stage-specific heart-rate measurement during repetitive stepping.

That is a different question.

Can I use my Garmin or Apple Watch?

Potentially, but the accuracy of wrist-based optical devices varies by model and activity.

For professional testing, a validated chest or upper-arm monitor is easier to justify.

Does the participant have to remove their shirt for a chest strap?

The strap needs suitable contact with the skin around the chest.

In occupational-health environments this can create privacy and dignity considerations, which is one reason upper-arm devices are attractive.

Does chest hair need to be shaved?

Routine shaving should not normally be necessary simply to use a heart-rate chest strap.

Correct positioning, tension and electrode contact are generally the first things to address.

Is ECG required?

No.

Routine Chester Step Testing is not a diagnostic exercise ECG.

Clinical ECG remains the reference measurement for validation research but would normally be disproportionate for routine CST administration.

What happens if the monitor loses signal during the test?

The assessor should not invent or estimate a heart rate.

Check the device, positioning and signal. Follow the appropriate test procedure and repeat or discontinue the assessment where necessary.

Should the same heart-rate monitor be used at retest?

Where practical, using the same device type and measurement method improves standardisation.

Final conclusion

Heart-rate monitor choice for the Chester Step Test should be based on more than convenience.

The device should provide measurements that are:

accurate
stable
repeatable
responsive
practical
appropriate for exercise

Electrical chest straps such as the Polar H10 remain the strongest practical benchmark, supported by excellent agreement with ECG and a long history of use in exercise testing.

The Polar Verity Sense is now a credible alternative rather than simply a convenience device. Independent evidence demonstrates strong performance across several exercise settings, and upper-arm placement can offer substantial practical advantages in occupational-health testing.

However, those findings should not be overstated.

At present, we have not identified direct published evidence demonstrating that Verity Sense and H10 are completely interchangeable within the Chester Step Test itself.

Finger pulse oximeters and wrist optical devices should be treated more cautiously as the primary heart-rate source for formal Chester Step Testing, particularly where occupational decisions may depend on the result.

The objective should not be loyalty to a specific device.

It should be:

high-quality, defensible exercise heart-rate measurement within a standardised Chester Step Test protocol.

References

1. Sykes K, Roberts A. The Chester step test—a simple yet effective tool for the prediction of aerobic capacity. Physiotherapy. 2004;90(4):183–188. doi:10.1016/j.physio.2004.03.008. The original validation paper describes continuous Polar heart-rate monitoring during the CST and reports the test’s validity and repeatability.

2. Sykes K. Chester Step Test. Occupational Medicine. 2018;68(1):70–71. doi:10.1093/occmed/kqx180. Describes practical CST administration, including heart-rate monitoring and RPE.

3. Schaffarczyk M, Rogers B, Reer R, Gronwald T. Validity of the Polar H10 Sensor for Heart Rate Variability Analysis during Resting State and Incremental Exercise in Recreational Men and Women. Sensors. 2022;22(17):6536. doi:10.3390/s22176536. Found strong agreement between H10 and ECG during incremental exercise.

4. Merrigan JJ, Stovall JH, Stone JD, Stephenson M, Finomore VS, Hagen JA. Validation of Garmin and Polar Devices for Continuous Heart Rate Monitoring During Common Training Movements in Tactical Populations. Measurement in Physical Education and Exercise Science. 2023;27(3):234–247. doi:10.1080/1091367X.2022.2161820. Compared H10, Verity and other devices with ECG during several exercise modes.

5. Navalta JW, Davis DW, Malek EM, et al. Heart rate processing algorithms and exercise duration on reliability and validity decisions in biceps-worn Polar Verity Sense and OH1 wearables. Scientific Reports. 2023;13:11736. doi:10.1038/s41598-023-38329-w. Reported Verity Sense as valid and reliable during trail running.

6. López-Belmonte O, Febles-Castro A, Gay A, Cuenca-Fernández F, Arellano R, Ruiz-Navarro JJ. Validity of the Polar Verity Sense during swimming at different locations and intensities. Scandinavian Journal of Medicine & Science in Sports. 2023;33(12):2623–2625. doi:10.1111/sms.14494.

7. Neudorfer B, et al. Validity of Four Consumer-Grade Optical Heart Rate Sensors for Assessing Volume and Intensity Distribution of Physical Activity. Scandinavian Journal of Medicine & Science in Sports. 2024. doi:10.1111/sms.14756. Compared upper-arm and wrist PPG sensors with medical-grade ECG across laboratory and free-living activities.

8. Liu Y, Barker AR, Li M, Gu Y, Williams CA. Validation of Polar Verity Sense for heart rate monitoring during school-based high-intensity interval training in adolescents. Journal of Sports Sciences. 2025;43(11):1076–1084. doi:10.1080/02640414.2025.2491163. Reported strong agreement with Polar H10 during HIIT.

9. Wrist-Worn and Arm-Worn Wearables for Monitoring Heart Rate During Sedentary and Light-to-Vigorous Physical Activities: Device Validation Study. JMIR Cardio. 2025;9. doi:10.2196/67110. Upper-arm Verity Sense showed very low error and high agreement across multiple activities.

10. Bent B, Goldstein BA, Kibbe WA, Dunn JP. Investigating sources of inaccuracy in wearable optical heart rate sensors. npj Digital Medicine. 2020;3:18. Discusses motion artefact and other sources of PPG measurement error.

11. Accuracy of pulse oximeters in estimating heart rate at rest and during exercise. Exercise comparison of pulse-oximeter pulse rate with ECG found underestimation at higher exercise heart rates.

12. Barker SJ, Shah NK. Effects of motion on the performance of pulse oximeters in volunteers. Demonstrated that motion can materially affect pulse-oximeter performance.

13. Effect of motion artefact on pulse oximeters: evaluation of four instruments and finger probes. Reported device- and probe-dependent effects of motion on pulse oximetry and pulse-rate registration.

14. The effect of motion on pulse oximetry and its clinical significance. Reviews the impact of motion on pulse-oximeter data quality and accuracy.

15. Validity of pulse oximetry during maximal exercise in normoxia, hypoxia and hyperoxia. Demonstrated exercise-related limitations in finger sensor performance and the effect of sensor location.