The present study aims to investigate the acute effects of inspiratory muscle warm-up (IWU) on 1RM performance in professional natural bodybuilders. The hypothesis is that IWU will lead to an increase in the pressure-generating capacity of the inspiratory muscles, thereby resulting in improved 1RM strength performance. The anticipated findings are expected to contribute not only to the enhancement of maximal strength performance but also to the improvement of exercise efficiency through increased respiratory muscle endurance. It is submitted that these outcomes may ultimately provide insights into the long-term sustainability of professional athletes' performance.

Twenty male athletes who had competed in national and international professional natural bodybuilding competitions were recruited for this study. The participants had an average experience in natural bodybuilding of 3.21 years, with a standard deviation of ± 1.44 years, and trained for more than five hours per week. The data collection period commenced in July 2025. The study was designed as a randomized controlled experimental trial. Participants were randomly assigned to two groups by a computerized program at three visits after the trial, based on their first measurement: inspiratory warm-up (IWU) group or control (CON) group.

The data collection period occurred between the 1st and 6th of July 2025. Prior to their involvement in the study, all subjects provided both verbal and written informed consent. Participants were invited to visit the laboratory on three separate occasions. During the preliminary visit, the subjects underwent a series of pulmonary function tests (PFTs). These included measurements of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). The participants were also subjected to 1RM testing and three practice trials of both the inspiratory warm-up and general training warm-up procedures [14]. On the second occasion, the PFT and MIP-MEP tests were conducted without any warm-up protocols, followed by the assessment of 1RM performance. On the third occasion, the participants were divided into two groups: the experimental group (IWU), which performed both inspiratory muscle and general warm-up exercises, and the control group (CON), which performed only the general warm-up. Each group comprised ten professional male natural bodybuilders. PFT and MIP-MEP tests were reassessed, and 1RM performance was measured immediately following the IWU intervention. In order to control for circadian variations, all laboratory visits were conducted at the same time of day (between 09:00 and 12:00). Participants were notified 72 hours in advance of each visit and were instructed to refrain from high-intensity physical activity during that period. It was determined that a recovery period of 72 hours should be observed between each testing session.

Inclusion Criteria:

• They were professional natural bodybuilders with less than three years of experience. ,

• Male professional natural bodybuilders aged 18-35 years

  --Full participation in training and matches during the previous 6 months,

• Ability to perform maximal exercise testing

Exclusion Criteria:

• Individuals were deemed ineligible on the basis of a medical history that included any chronic or acute respiratory disease.
• Individuals were considered ineligible if they were taking any prescription medication that could affect their response to exercise.
• In accordance with the stipulated criteria, individuals were deemed to be ineligible for participation in the study if they had a history of current smoking or had smoked within the past year.
• Individuals were considered ineligible for participation in the study if they had participated in similar studies within the previous six months.
• Prior to participation, all individuals were required to sign a formal waiver, thereby affirming their adherence to the World Anti-Doping Agency Code.

Male

Individual participant data (IPD) will not be shared because the dataset consists of a small sample of elite athletes, and sharing de-identified data could still pose a risk of participant re-identification. In addition, no data-sharing agreement or participant consent for IPD sharing was established at the time of study design. Aggregate data supporting the findings are reported within the published article.