Validation of a Novel Incremental Step Test for Assessment of Cardiopulmonary Fitness and Ventilatory Thresholds in Adults (VALID-IST)

The purpose of this single-group diagnostic validation and test-retest reliability study is to determine whether a novel Incremental Step Test (IST) can accurately assess cardiorespiratory fitness and ventilatory thresholds in healthy adults compared with an established laboratory-based cycle ergometer Cardiopulmonary Exercise Test (CPET). The main questions are whether the step test can elicit reliable physiological responses sufficient to identify the anaerobic threshold and respiratory compensation point, and whether it produces reproducible results when repeated under standardised conditions. The study will compare the incremental step test (IST) with CPET to assess whether the IST provides similar peak and submaximal physiological measures and agreement with CPET comparator. Participants will complete three laboratory exercise tests across separate visits: one maximal CPET on a cycle ergometer, followed by two repeated ISTs performed on a 25 cm step board following the audio metronome.

Study Overview

• Status: Enrolling by invitation
• Conditions: Pulmonary Function; Cardiorespiratory Fitness; Cardiac Function; Exercise Test; Metabolic Health
• Intervention / Treatment: Diagnostic test: Cardiopulmonary Exercise Test; Diagnostic test: Incremental Step Test

Detailed Description

Participants will attend three laboratory visits separated by at least 3 days and conducted at similar times of the day. The first visit will include screening, anthropometric assessment, and a maximal CPET on an electronically braked cycle ergometer using a ramp protocol of 25 W/min for males and 20 W/min for females. Participants will complete 3 minutes of unloaded cycling followed by incremental protocol while maintaining the cadence at least 60 rpm, and the test will be terminated if they can no longer can sustain this cadence. Following CPET, participants will complete a 6-minute familiarisation session to practise the stepping activity, including the up-up-down-down stepping technique and alternation of the leading leg every 2 minutes. The second and third visits will involve repeated IST trials performed on 25 cm step board, with cadence progressed from 20 beats per minute and increased by 4 beats per minute every 20 seconds until volitional exhaustion. The IST will be terminated if the participant is unable to maintain the prescribed stepping rhythm for more than 15 seconds. Continuous breath-by-breath gas exchange, ECG, and heart rate monitoring will be used during testing to characterise peak performance and ventilatory threshold responses. Agreement between the step test and CPET, as well as test-retest reproducibility of the IST, will be evaluated to determine whether the new protocol could support more individualised exercise prescription in stepping-based activities.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Edinburgh, United Kingdom, EH14 4AS
    • Oriam Scotlant Performance Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Healthy adults aged 18 to 55 years.
2. Body mass index between 18.5 and 29.9 kg/m².
3. Non-smoker.
4. No known cardiovascular, respiratory, metabolic, neurological, or musculoskeletal conditions that would contraindicate maximal exercise testing.
5. Able to provide written informed consent.
6. Willing and able to complete one Cardiopulmonary Exercise Test and two Incremental Step Test sessions.

Exclusion Criteria:

1. Age younger than 18 years or older than 55 years.
2. Body mass index below 18.5 kg/m² or above 29.9 kg/m².
3. Current smoker or use of nicotine products.
4. Known cardiovascular, respiratory, metabolic, neurological, or musculoskeletal conditions that may affect exercise performance or make maximal exercise testing unsafe.
5. Any contraindication to maximal exercise testing according to established exercise testing guidelines.
6. Use of medications known to significantly affect cardiovascular, respiratory, or metabolic responses to exercise.
7. Current injury, illness, or infection that may limit participation in exercise testing.
8. Pregnancy.
9. Inability to provide informed consent.

10. Inability to complete study procedures or attend all required study visits.

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Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Incremental Step Test Validation Protocol; Participants will complete one laboratory-based Cardiopulmonary Exercise Test followed by two Incremental Step Test sessions conducted on separate visits. The first visit will include screening, anthropometric measurements, and a maximal incremental CPET on an electronically braked cycle ergometer using an individualised ramp protocol set at 25 W/min for males and 20 W/min for females, after 3 minutes of unloaded cycling. The second and third visits will involve two repeated incremental step tests on a standardised 25 cm step, with cadence starting at 20 beats per minute and increasing by 4 beats per minute every 20 seconds until volitional exhaustion. The CPET will be terminated if participants could not maintain a cadence of at least 60 rpm, and the step test will be terminated if participants could not maintain the prescribed stepping rhythm for 15 consecutive seconds. Exercise ECG, continuous heart rate, and breath-by-breath gas exchange will be recorded during all exercise tests.

Diagnostic test: Cardiopulmonary Exercise Test; A maximal incremental exercise test performed on a cycle ergometer with continuous breath-by-breath gas exchange and heart rate monitoring to assess cardiorespiratory fitness and physiological response; Diagnostic test: Incremental Step Test; A progressive step test using a standardised 25 cm step platform. Participants will complete a 3-minute warm-up at 20 beats per minute before cadence increases by 4 beats per minute every 20 seconds until volitional exhaustion or predefined termination criteria are reached.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Between-method agreement in oxygen uptake at Anaerobic Threshold (AT)	Agreement between the Incremental Step Test and the established laboratory-based cycle ergometer Cardiopulmonary Exercise Test comparator for oxygen uptake at Anaerobic Threshold (mL/min), will be assessed using intraclass correlation coefficients and Bland-Altman analysis.	Baseline (Day 1-CPET) and IST assessments at Visits 2 and 3, scheduled at 3-7-day intervals.
Between-method agreement in oxygen uptake at Respiratory Compensation Point (RCP)	Agreement between the Incremental Step Test and the established laboratory-based cycle ergometer Cardiopulmonary Exercise Test comparator for oxygen uptake at Respiratory Compensation point / Ventilatory Threshold 2 (mL/min), will be assessed using intraclass correlation coefficients and Bland-Altman analysis.	Baseline (Day 1-CPET) and IST assessments at Visits 2 and 3, scheduled at 3-7-day intervals.
Between-method agreement in Peak Oxygen Uptake (VO2peak)	Peak oxygen uptake will be defined as the highest 30-second rolling average value recorded prior to test termination.	Baseline (Day 1-CPET) and IST assessments at Visits 2 and 3, scheduled at 3-7-day intervals.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Test-retest reliability of oxygen uptake at Anaerobic Threshold (AT)	Test-retest reliability of oxygen uptake at AT (mL/min) derived from the Incremental Step Test (IST) between the first and second IST visits.	(Day 3-IST Visit 2) and IST Visit 3, scheduled 3-7 days apart.
Test-retest reliability of oxygen uptake at Respiratory compensation point (RCP)	Test-retest reliability of oxygen uptake at RCP (mL/min) derived from the Incremental Step Test (IST) between the first and second IST visits.	(Day 3-IST Visit 2) and IST Visit 3, scheduled 3-7 days apart.

Collaborators and Investigators

• Sponsor: Heriot-Watt University
• Investigators: Principal Investigator: David King, BSc, MSc, PhD, Heriot-Watt University

Study record dates

Study Major Dates

• Study Start (Actual): July 20, 2026
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): October 30, 2026

Study Registration Dates

• First Submitted: September 8, 2026
• First Submitted That Met QC Criteria: September 14, 2026
• First Posted (Actual): September 18, 2026

Study Record Updates

• Last Update Posted (Actual): September 18, 2026
• Last Update Submitted That Met QC Criteria: September 14, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: reliability; validation; Exercise testing; CPET; gas exchange; anaerobic threshold; Cardiopulmonary Exercise Testing; VO2 peak; Ventilatory threshold; Incremental Step Test
• Additional Relevant MeSH Terms: Investigative Techniques; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Techniques, Respiratory System; Diagnostic Techniques, Cardiovascular; Heart Function Tests; Respiratory Function Tests; Ergometry; Exercise Test
• Other Study ID Numbers: Ref: 2025-12928-16897

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No individual participant data will be shared publicly. The study will report findings using aggregated and de-identified data. Individual participant data will be retained securely by the research team in accordance with Heriot-Watt University research governance and data protection requirements.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No