Hypoxic Environment on EIB and Performance in Race Walkers

We invite you to participate in this research study. Your participation is entirely voluntary, and you may refuse to participate or withdraw from the experiment at any time without any penalty.

Before deciding whether to participate, you need to understand the content of this study, the potential risks and benefits of participation, and what you will be asked to do in this study. You may also consult with your family, friends, or doctor about this study and this consent form. If you have any questions about this study or this consent form, please contact the principal investigator and collaborating researchers. If you decide to participate in this study, you must sign this consent form. We will provide you with a signed copy of this consent form for your records.

• What are the objectives of this study? Objective 1: To diagnose whether you have exercise-induced bronchoconstriction (EIB).

Objective 2: To investigate whether EIB is induced or aggravated at different stages of your altitude training period.

Objective 3: To investigate the impact of having or not having EIB on your specific athletic performance during altitude training.

• What will you need to do in this study?

Over the next 2 to 4 months, you are required to follow and cooperate with the researchers' instructions. If you have any questions or feel unwell, please communicate with the research team promptly. The specific details are as follows:

• Complete a total of 4 early morning fasting blood draws (with an interval of 2 weeks between each collection). Blood will be drawn from the elbow vein, with approximately 4 ml of blood collected each time. It is important to note that these blood draws are routine monitoring tests routinely conducted for the sports team.
• Complete a total of 4 laboratory exercise-induced bronchoconstriction tests (with an interval of at least 2 weeks between each test). This test follows the standard procedures recommended by the American Thoracic Society (ATS) guidelines. It is important to note that this test is a routine monitoring test routinely conducted for the sports team. Avoid vigorous exercise for 24 hours prior to each test. Perform a brief warm-up before the test, wear a Polar heart rate monitor and a nose clip, and then run on a treadmill. This is a high-intensity exercise protocol: during the first 2-3 minutes, the treadmill speed and/or incline will be progressively increased until your heart rate reaches 85% of your HRmax (HRmax is calculated using the Nex formula: HRmax = 211 - 0.64 × age). Subsequently, you will maintain the current intensity/incline and continue exercising for 6-8 minutes. A pulmonary function test will be performed immediately before exercise, as well as at 1, 3, 5, 7, 10, 15, and 30 minutes after exercise (a total of 8 tests).
• Complete a total of 4 standardized maximal oxygen uptake (VO2max) tests (with an interval of at least 2 weeks between each test). Avoid vigorous exercise for 24 hours prior to each test. On the test day, arrive early at the testing site, wear a breathing mask and check for airtightness, and wear a Polar watch to test the stability of the contact signal. Once ready, you will warm up by walking on the treadmill at a speed of 4-6 km/h with a 0° incline for 3-5 minutes. Then, the test begins. You will exercise at a speed of 8 km/h for 5 minutes, after which the speed will be increased linearly at an average rate of 2 km/h every 3 minutes. For female athletes, when the speed reaches 14-16 km/h, the speed will stop increasing, and the incline will be increased at a rate of 1° per minute. For male athletes, when the speed reaches 16-19 km/h, the speed will stop increasing, and the incline will be increased at a rate of 1° per minute until exhaustion. Exhaustion is considered to have been reached when any two of the following criteria are met:

• The athlete is unable to maintain the predetermined speed of the protocol or voluntarily requests to stop; 2. VO2 no longer increases, showing a plateau phenomenon for more than 30 seconds; 3. The exercise heart rate exceeds 10% of the calculated maximum heart rate [(211 - 0.64 × age) - 10 bpm].

• Wear a Polar heart rate monitor before each specialized training session and remove it after the session. Complete the RPE (Rating of Perceived Exertion) and exercise-related respiratory symptom questionnaires.

• How long will it take to participate in this study?

The entire process will take approximately 2 to 4 months (depending on actual progress) and includes two phases: plains training and altitude training. The time commitments are as follows:

Each blood draw will take approximately 3 to 5 minutes. Each exercise-induced bronchoconstriction test, including a brief warm-up and wearing a Polar heart rate monitor, will take approximately 40 to 50 minutes.

Each VO2max test will take approximately 20 to 30 minutes. Each fitting and calibration of the Polar watch will take approximately 5 to 10 minutes.

Each post-training questionnaire will take approximately 2 to 5 minutes.

• What are the potential risks or discomforts?

Known risks associated with this type of research include:

Blood collection: You may feel dizzy during the blood draw. If this occurs, please inform the researcher immediately. Additionally, the collection site may sometimes become red, painful, bruised, bleed, or become infected.

Pulmonary function test: Due to the forceful exhalation required, you may experience temporary dizziness for approximately 20 seconds or respiratory muscle fatigue, which are normal physiological responses and will typically recover within 0.5 to 1 minute after each test. There is a very low probability of experiencing chest pain. If this occurs, you must inform the researcher immediately and indicate your willingness and ability to continue with the test.

Laboratory exercise-induced bronchoconstriction test and VO2max test: These may result in exercise-induced fatigue (100% likelihood) and delayed onset muscle soreness (moderate likelihood). If you have EIB, you may experience respiratory discomfort during the test, such as difficulty breathing, excessive wheezing, or chest tightness. In principle, to ensure the accuracy of the study, we hope you will persist as much as possible. However, if you feel you cannot continue, please signal to us immediately, and we will terminate the test promptly. If necessary, we may provide 400 µg of salbutamol aerosol (200 µg × 2 puffs) to alleviate your symptoms.

Note: Salbutamol is a standard medication (bronchodilator) used to treat acute EIB episodes. According to the latest policies of the IOC Medical Committee and the World Anti-Doping Agency (2024), inhaled salbutamol in aerosol form, with a single dose ≤400 µg and a cumulative dose over 24 hours ≤800 µg, falls within the therapeutic use exemption range and does not constitute a doping violation. Therefore, in the event of such a situation, the decision to use it will be made jointly based on the opinions of you, your head coach, and the medical officer responsible.

• What are the potential benefits of participating in this study? If you do not have EIB: You will receive a simplified version of the "EIB Prevention and Management Handbook" compiled by us, which will help you properly understand the mechanisms, hazards, and protective measures related to EIB, and prevent the occurrence of EIB.

If you have EIB: After the experiment concludes, we will provide the coaching staff with a detailed report on your specific condition and work together with them to develop intervention strategies and conduct periodic evaluations. You will be added to our EIB athlete registry, and we will provide follow-up (1-2 times per year) as well as EIB consultation services to help you mitigate the negative effects of EIB.

• Will you receive compensation for participating in this study? Upon completing the entire experiment, you will receive a reward: one commemorative gift.

If you withdraw from the study, whether voluntarily or involuntarily, you will not receive the reward.

• What if you get injured while participating in this research? For any organic injuries you may suffer as a result of participating in this research, Shanghai Sports University will not cover your medical expenses or provide any other form of financial compensation. You will not waive any of your legal rights by signing this consent form.

• Can one leave the study halfway? You can withdraw at any time without any penalty.

• How will this research protect your personal privacy? The experimental data and informed consent forms will be encrypted using codes and pseudonyms, ensuring that your personal information is not disclosed or directly identifiable from the relevant data.

• The Research Ethics Committee of Shanghai University of Sport and how it protects you? This committee will review all studies involving human subjects, such as the study you are considering participating in. The committee is responsible for protecting the rights and welfare of research participants. The committee complies with national laws and guidelines, reviews each study to ensure that the risks of all research projects are minimized as much as possible.

If you have any doubts about the rights of the subjects, or if you think you have been treated unfairly, or if you have any questions about this study, you can contact the committee. The contact information is provided below.

• Who can you contact if you have any questions? If you have any questions, confusion, complaints regarding participation in this research, or any doubts about your rights as a research subject, you can contact the main researcher and contact person listed on the first page of this consent form. You can also directly contact the Shanghai Sports University Research Ethics Committee at the email address [email protected].

Inclusion criteria

Only athletes who meet the following conditions simultaneously can be included in this study:

• Engaged in race walking specialized training;
• The athlete's technical grade reaches the national first-class standard or above (the athlete's level level is ≥ Tier 3);
• Regular professional training is still maintained at present.

Exclusion criteria

• Presence of chronic cardiopulmonary diseases (e.g., chronic obstructive pulmonary disease, pulmonary heart disease, known structural heart disease) or other significant medical conditions (e.g., uncontrolled hypertension, depression) that could confound respiratory test results or pose a risk during intense exercise;
• Known hypersensitivity to hypoxia or history of severe altitude sickness (e.g., high-altitude pulmonary edema [HAPE], high-altitude cerebral edema [HACE]);
• Sickle cell trait or disease;
• History of chest surgery within the preceding 6 months;
• Any active lung infection (e.g., pneumonia, bronchitis) or systemic infection within 3 weeks before the examination;
• Cessation of regular training for 2 or more weeks immediately before the examination, to ensure participants were in their typical training state;
• Experience of a moderate or severe upper respiratory tract infection (e.g., common cold) within the week preceding the examination;
• Individuals who reported chest pain or experienced syncope (fainting) during the spirometry maneuver;
• Individuals who were unable to understand the test instructions or unwilling to cooperate fully with the testing procedures, as determined by the research staff.