UMIN-ICDS Clinical Trial

Public title

Effects of breathing low-oxygen air during recovery periods on exercise power and physiological responses during repeated high-intensity cycling

Acronym

IEH Cycling Study

Scientific Title

Effects of Exercise and Training under Hypoxic Conditions on the Human Body

Scientific Title:Acronym

IEH Cycling Study

Region

Japan

Condition

Healthy adults

Classification by specialty

Adult

Classification by malignancy

Others

Genomic information

NO

Narrative objectives1

This study aims to investigate the effects of inter-effort hypoxic exposure (IEH) on mean power output and acute physiological responses during repeated-sprint cycling exercise in healthy adult males who engage in regular physical exercise. A randomized crossover design will be used, in which each participant completes three experimental conditions: normoxia (NOR), continuous hypoxia (HYP), and inter-effort hypoxic exposure (IEH). The primary outcome will be mean power output across 16 sprints, with the comparison between IEH and HYP designated as the primary contrast. Secondary outcomes will include peripheral oxygen saturation, peak power output, blood lactate concentration, and rating of perceived exertion.

Basic objectives2

Efficacy

Basic objectives -Others

Trial characteristics_1

Exploratory

Trial characteristics_2

Explanatory

Developmental phase

Not applicable

Primary outcomes

Mean power output (MPO, W) during repeated-sprint cycling exercise. Under each experimental condition, participants will perform four sets of four 10-s all-out cycling sprints (16 sprints in total) against a resistance equivalent to 7.5% of body mass. MPO will be calculated for each 10-s sprint, and the arithmetic mean of all 16 sprint values will be used as the representative MPO for each condition. MPO will be assessed under normoxic (NOR), continuous hypoxic (HYP), and inter-effort hypoxic exposure (IEH) conditions, with IEH versus HYP designated as the primary contrast.

Key secondary outcomes

1. Peripheral oxygen saturation (SpO2, %): Measured before warm-up and at 0, 30, 60, 90, 120, 150, 180, 210, and 240 s after each set. Mean observed SpO2, minimum observed SpO2, and time-dependent changes during each recovery period will be evaluated.
2. Peak power output (PPO, W): Measured during each 10-s sprint and compared across experimental conditions and sets.
3. Blood lactate concentration (mmol/L): Measured using fingertip capillary blood samples collected before warm-up and 120 s after each set.
4. Rating of perceived exertion (RPE): Assessed immediately after each set using the modified Borg CR10 scale.

Study type

Interventional

Basic design

Cross-over

Randomization

Randomized

Randomization unit

Individual

Blinding

Open -no one is blinded

Control

Active

Stratification

NO

Dynamic allocation

NO

Institution consideration

Institution is not considered as adjustment factor.

Blocking

YES

Concealment

Numbered container method

No. of arms

6

Purpose of intervention

Educational,Counseling,Training

Type of intervention

Behavior,custom

Interventions/Control_1

Participants will complete three repeated-sprint cycling trials in the following order: NOR, HYP, and IEH, with at least 72 h between trials.
In each trial, participants will perform four sets of four 10-s all-out cycling sprints (16 sprints in total) at a resistance equivalent to 7.5% of body mass. Passive recovery will be 20 s between sprints and 5 min between sets.
In the NOR condition, participants will breathe ambient room air throughout exercise and recovery. In the HYP condition, participants will breathe hypoxic gas (FiO2 = 13.5%) continuously from the start of the first set until the end of the 5-min recovery after the fourth set.
In the IEH condition, all sprints and 20-s intra-set recovery periods will be performed under normoxia. During the 5-min recovery periods after sets 1-3, participants will breathe hypoxic gas (FiO2 = 13.5%) for the first 4 min 30 s, followed by normoxia for the final 30 s. After the fourth set, hypoxic exposure will continue throughout the entire 5-min recovery period.

Interventions/Control_2

Participants will complete the three repeated-sprint cycling conditions in the following order: NOR, IEH, HYP. The exercise protocol and oxygen exposure conditions will be identical to those described in Intervention 1, with at least 72 h between trials.

Interventions/Control_3

Participants will complete the three repeated-sprint cycling conditions in the following order: HYP, NOR, IEH. The exercise protocol and oxygen exposure conditions will be identical to those described in Intervention 1, with at least 72 h between trials.

Interventions/Control_4

Participants will complete the three repeated-sprint cycling conditions in the following order: HYP, IEH, NOR. The exercise protocol and oxygen exposure conditions will be identical to those described in Intervention 1, with at least 72 h between trials.

Interventions/Control_5

Participants will complete the three repeated-sprint cycling conditions in the following order: IEH, NOR, HYP. The exercise protocol and oxygen exposure conditions will be identical to those described in Intervention 1, with at least 72 h between trials.

Interventions/Control_6

Participants will complete the three repeated-sprint cycling conditions in the following order: IEH, HYP, NOR. The exercise protocol and oxygen exposure conditions will be identical to those described in Intervention 1, with at least 72 h between trials.

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

18

years-old

<=

Age-upper limit

Not applicable

Gender

Male

Key inclusion criteria

1. Healthy males aged 18 years or older.
2. Individuals who regularly engage in physical exercise at least twice per week for at least 30 minutes per session.
3. Individuals who are considered suitable for high-intensity cycling exercise and hypoxic exposure based on a health questionnaire and interview.
4. Individuals who have received sufficient information about the study objectives, procedures, and potential risks and have provided written informed consent.
5. Individuals who are able to participate in all experimental conditions specified in the study protocol.

Key exclusion criteria

1. Individuals with cardiovascular, respiratory, metabolic, or other medical conditions that may interfere with or contraindicate high-intensity exercise or hypoxic exposure.
2. Individuals with a history of chest pain, severe dyspnea, dizziness, syncope, or other concerning symptoms during high-intensity exercise.
3. Individuals with musculoskeletal disorders that prevent safe performance of high-intensity cycling exercise.
4. Individuals taking medications that may affect exercise performance, cardiovascular or respiratory responses, or oxygen saturation, when such medications are considered to compromise participant safety or study outcomes.
5. Individuals considered unsuitable for hypoxic exposure or high-intensity exercise based on a health questionnaire, interview, or resting oxygen saturation.
6. Individuals otherwise deemed unsuitable for participation by the principal investigator for safety-related or study-related reasons.

Target sample size

18

Name of lead principal investigator

1st name	Toshihiro
Middle name
Last name	Yasuda

Organization

Fukushima University

Division name

Faculty of Human Development and Culture

Zip code

960-1296

Address

1 Kanayagawa, Fukushima 960-1296, Japan

TEL

024-548-8209

Email

yasuda@educ.fukushima-u.ac.jp

Name of contact person

1st name	Toshihiro
Middle name
Last name	Yasuda

Organization

Fukushima University

Division name

Faculty of Human Development and Culture

Zip code

960-1296

Address

1 Kanayagawa, Fukushima, Japan

TEL

024-548-8209

Homepage URL

Email

yasuda@educ.fukushima-u.ac.jp

Institute

Fukushima University

Institute

Department

Personal name

Organization

Fukushima University

Organization

Division

Category of Funding Organization

Self funding

Nationality of Funding Organization

Japan

Co-sponsor

Name of secondary funder(s)

Japan Society for the Promotion of Science (JSPS KAKENHI, Grant Number 25K14687)

Organization

Fukushima University Research Ethics Committee

Address

1 Kanayagawa, Fukushima, Japan

Tel

024-548-5298

Email

kyoudo@adb.fukushima-u.ac.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

福島大学 保健体育棟107号室 生理学実験室（福島県）

Date of disclosure of the study information

2026

Year

11

Month

11

Day

URL releasing protocol

Publication of results

Unpublished

URL related to results and publications

Number of participants that the trial has enrolled

Results

Results date posted

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

Participant flow

Adverse events

Outcome measures

Plan to share IPD

Yes (conditional sharing upon reasonable request)

IPD sharing Plan description

De-identified individual participant data will not be made publicly available in an open repository. Data may be shared by the principal investigator upon reasonable request, subject to evaluation of the research purpose, ethical appropriateness, and protection of participant confidentiality.

Recruitment status

Preinitiation

Date of protocol fixation

2026

Year

11

Month

11

Day

Date of IRB

2025

Year

03

Month

27

Day

Anticipated trial start date

2026

Year

11

Month

16

Day

Last follow-up date

2026

Year

12

Month

31

Day

Date of closure to data entry

Date trial data considered complete

Date analysis concluded

Other related information

This study is an independent intervention trial conducted under the broader research protocol entitled "Effects of Exercise and Training under Hypoxic Conditions on the Human Body," approved by the Fukushima University Research Ethics Committee (approval number 2024-40; March 27, 2025). This trial is distinct from the previous VHL-RST study conducted under the same ethics approval and will be prospectively registered in UMIN-CTR before enrollment of the first participant.

Registered date

2026

Year

11

Month

11

Day

Last modified on

2026

Year

11

Month

11

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000072780