Inspiratory Muscle Activation and Post-Exercise Recovery in Professional Football Players

Sierra Varona SL

Status: Not yet enrolling

Conditions: Sports Physical Therapy; Injury;Sports

Treatments: Device: Inspiratory muscle activation via threshold device; Device: Inspiratory muscle activation via phrenic nerve modulation

Study type: Interventional

Funder types: Other

Identifiers

NCT07373158

021

Details and patient eligibility

About

Respiratory muscles play a fundamental role in sports performance. Fatigue of these muscles induces changes in maximal inspiratory pressure and autonomic nervous system activity, thereby compromising the athlete's recovery process. The primary aim of this study is to evaluate the specific effects of different inspiratory muscle activation modalities on post-exercise recovery in professional male football players. The study seeks to determine which of the three modalities-bilateral phrenic nerve electrical stimulation, a threshold loading device protocol, or inactivity-provides greater benefits for recovery. The effectiveness of these interventions will be assessed using two key outcome variables: maximal inspiratory pressure (MIP) and heart rate variability (HRV).

This study is designed as a randomized clinical trial (RCT) in which participants will be allocated into three intervention groups: a bilateral phrenic nerve electrical stimulation group (EG1), in which involuntary diaphragmatic contractions will be induced using an electrotherapy device with current applied to the phrenic nerves; a threshold device group (EG2), in which participants will perform breathing against submaximal inspiratory loads equivalent to 40% of their MIP; and a control group (CG), which will remain seated for a period equivalent to the duration of the other interventions. Group allocation will be ensured through randomization using Microsoft Excel.

Regarding statistical analysis, data normality will be assessed using the Shapiro-Wilk test. Comparisons of quantitative variables will be performed using Student's t test when normality assumptions are met, or the Mann-Whitney U test otherwise. A p value < 0.05 will be considered statistically significant.

Enrollment: 30 estimated patients

Sex: Male

Ages: 18 to 40 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Male professional football player.
• Currently under an active professional contract and participating in regular competition.
• Aged between 18 and 40 years.
• No participation in inspiratory muscle training (IMT) programs in the past 12 months.
• Signed informed consent provided by the participant.

Exclusion criteria

• Musculoskeletal injuries or surgical interventions within the past 6 months.
• Use of medications affecting cardiac or respiratory function (e.g., beta-blockers, beta-adrenergic inhibitors).
• Presence of any acute and/or chronic disease (cardiorespiratory, neurological, metabolic, oncological, etc.).
• Use of tobacco, recreational drugs, or stimulant substances.
• Metallic implants in the cervical region.
• Presence of a pacemaker.
• Current participation in other inspiratory muscle training programs.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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30 participants in 3 patient groups

Phrenic Electrostimulation

Experimental group

Description:

The participant will be placed in the supine position, and the intervention will be performed using a pen-type electrode. Bilateral stimulation of the phrenic nerves will be applied below the sternal portion of the sternocleidomastoid muscle at the C3-C5 level. The electrical stimulators will be set to a mean frequency of 50 Hz and a pulse width of 300 μs. Stimulation intensity will be progressively increased until a visible diaphragmatic contraction (abdominal movement) is observed and reaches the maximum level tolerable for the player. The stimulation protocol will consist of two sets of 30 repetitions, delivered in bilateral cycles of 6 s ON (stimulation) and 10 s OFF (rest), including a 2-minute rest period between sets. Concurrently with the perception of the involuntary contraction, the participant will perform a voluntary contraction through diaphragmatic inspiration.

Treatment:

Device: Inspiratory muscle activation via phrenic nerve modulation

Inspiratory muscle warm-up group

Active Comparator group

Description:

Participants will breathe against submaximal inspiratory loads following a protocol consisting of two sets of 30 breaths, equivalent to 40% of their MIP, using the Breathcare MIP/MEP device (Big Breathe®, GH Innotek Co., Ltd., Busan, Republic of Korea). Breathing will be performed using a self-paced pattern, provided that a ratio of approximately 1 s of inspiration to 2 s of expiration is maintained to avoid hyperventilation. The session duration will correspond to the exact time required to complete the two sets of breaths, including a 2-minute rest period between sets, with an estimated total duration of approximately 15 minutes.

Treatment:

Device: Inspiratory muscle activation via threshold device

Control group

No Intervention group

Description:

Participants in this group will remain seated at rest in a quiet and controlled environment. During this period, they will breathe normally. The rest duration for this group will be identical to that of the other interventions.