The main objective of the study is to study the changes in FEV1 with the introduction of the specific inspiratory muscle training programme in the training programme of the popular athletes included. In addition, the secondary aims are to observe the differences in the respiratory capacities of the patients, in the vital signs, VO2 max, respiratory frequency and cardiac variability, as well as to assess the running performance of the participants.

Participants will be assigned to one of 2 study groups: IMT group (n=20) or not-IMT group (n=20) The IMT group will perform inspiratory muscle training in conjunction with the conventional marathon training plan. The not-IMT group will follow only the conventional marathon training plan. The study will be conducted over a 12 week period.

Inclusion Criteria:

• Individuals willing to follow the 16-week running training plan
• Possibility of combining aerobic training with inspiratory muscle training
• Previous half marathon runner

Exclusion Criteria:

• - Exclusive or professional dedication to athletics
• Previous or current use of respiratory muscle training.
• Inadequate or health risk physical condition
• Significant chronic cardiorespiratory diagnoses (e.g. moderate-severe COPD).
• Neurological, muscular or neuromuscular problems that interfere with the ability to participate in tests and training protocols.
• Discontinuity in the performance of training.
• A terminal illness or any other major medical contraindication
• Lack of informed consent

The evaluators are unaware of the assignment at all times. Outcomes assessor will discover group assigment after data analysis.