Background/Objectives: A major importance is now accorded to respiratory muscle weakness resulting from exposure to invasive mechanical ventilation (IMV) in intensive care unit patients. Some authors suggested that Inspiratory Muscle Training (IMT) could increase the chances of weaning off IMV. This systematic review examined the efficacy of IMT on weaning success in mechanically ventilated patients. Methods: A literature search was conducted on PubMed, Cochrane, and PEDro until June 2023. Weaning success, maximum inspiratory pressure (MIP), and Rapid Shallow Breathing Index (RSBI) were the outcome measures included. Results: Seven randomized controlled trials, including 517 participants under IMV for at least 48 h, were included in the review. From a qualitative point of view, a significant increase in MIP and a significant decrease in RSBI were found in the intervention group during the analysis. However, weaning success was the same between the intervention and control groups. No significant association was found between weaning success and the increase of MIP or the decrease of RSBI. Furthermore, it could not be demonstrated that a positive change in MIP or RSBI would increase the weaning success rates. Conclusions: From a qualitative point of view, IMT is effective in increasing MIP and decreasing RSBI. However, IMT has no significant impact on weaning success. Further research is recommended to analyze the effect of IMT on weaning success.

Introduction: Exercise-induced hypoalgesia is a phenomenon in which exercise bouts induce a reduction in pain sensitivity. Apnea training involves similar characteristics that could potentially induce hypoalgesia. Objectives: The objectives of this study are to explore the effect of apnea training on hypoalgesia; assess the correlation between conditioned pain modulation (CPM) response and apnea-induced hypoalgesia; and examine the association between hypoalgesia with hypoxemia, and heart rate (HR) during apnea. Methods: A randomized controlled trial was conducted comparing a walking protocol employing intermittent apnea compared with normal breathing in healthy volunteers. Hypoalgesia was tested with pressure pain thresholds (PPTs) and CPM. Oxygen saturation (SpO₂) and HR were also tested. Results: Relevant but not significant changes were detected in the thumb (MD = 0.678 kg/cm²), and tibialis (MD = 0.718 kg/cm²) in favor of the apnea group. No significant differences were detected in CPM. The apnea group presented lower SpO₂, but HR values similar to those of the control group during the intervention. Basal CPM and intrasession hypoxemia significantly correlated with the PPT response. However, HR did not correlate with the PPT response. Conclusions: The current results suggest a trend, though not statistically significant, toward an improvement in the PPT in favor of apnea training compared to normal breathing. Nevertheless, subjects who presented greater basal CPM and lower oxygen saturation during the session presented a greater PPT response, suggesting the possibility of mediators of response. Future investigations should clarify this phenomenon.