On a previous post in my blood pressure series, u/OrganicTransistor suggested trying to strengthen my respiratory muscles based on the results in this paper by Seals and co-workers.
The paper, the authors report a pre-registered, sham-controlled, double-blind RCT of whether inspiratory muscle strength training lowers blood pressure. Here’s a quick summary:
- 36 participants, all with blood pressure >120 mmHg systolic and no indication of uncontrolled diabetes, cholesterol, or thyroid disease or severe obesity.
- Participants underwent 6 weeks of IMST using a PowerBreathe K3
- Each week, the experimenters measured the participants max inspiratory pressure
- The experimental group trained daily at 75% of max inspiratory pressure (5 sets of 6 breaths with 1 min. rest in-between)
- The control group trained at very low resistance.
- Results:
- Systolic: experimental group saw a decrease of 9 mmHg systolic vs. 3 mmHg systolic for the sham-training group (P < 0.01 for difference of means).
- Diastolic: experimental group saw a decrease of 2 mmHg systolic vs. 0 mmHg systolic for the sham-training group (P = 0.03 for difference of means).
- Results were similar in magnitude and statistically significant when stratified by sex.
- Effect persisted 6 weeks after training was stopped.
This is a huge effect size for blood pressure reduction. Given that it was pre-registered, blinded, and sham-controlled, I think it’s worth trying to see if it works for me.
Towards that end, I’m pre-registering the following self experiment:
- Approach
- I will replicate the published procedure as much as possible, with the following changes:
- Instead of a PowerBreathe K3, I will use a PowerBreathe HR for training and an AeroFit Pro for measuring my progress
- Reason: The K3 is ~$500, out of my price range for an initial replication
- Instead of setting the resistance to a percentage of my max inspiratory pressure, I will increase the load until it is difficult to maintain steady, high pressure for the full 5 sets. Then I will increase by 0.25 turns of the load setting knob whenever I feel able to do so.
- Reason: The HR does not have the ability to set a specific load force. The procedure I’m using is the one recommended for training in the PowerBreath HR manual
- Instead of a PowerBreathe K3, I will use a PowerBreathe HR for training and an AeroFit Pro for measuring my progress
- I will replicate the published procedure as much as possible, with the following changes:
- Procedure
- Once per day, I will do 5 sets of 6 breaths, with 1 min. rest in-between sets using the PowerBreathe HR.
- If I struggle to complete all sets, I will leave the load setting as-is. If not, I will increase by 0.25 turns of the load setting knob.
- Every 3 days, I will measure my maximum inspiratory pressure, expiratory pressure, and inspiratory volume using an Aerofit Pro
- Each morning at ~6am, I will measure my blood pressure and pulse using an Omron Evolve
- Measurements
- Blood pressure:
- Instrument: Omron Evolve blood pressure meter
- Method:
- For each measurement, I will place the meter on my left arm, ~4 cm above my elbow. Measurements will be taken seated, with my feet on the ground and arms resting on a flat surface at a comfortable height (same every time).
- 5 measurements will be taken with no pause in-between measurements (other than to write down the result) and the average of the 5 measurements will be used.
- Breathing:
- Instrument: AeroFit Pro
- Method:
- I will follow the instructions provided by the AeroFit app
- 3 measurements will be taken with no pause in-between measurements (other than to write down the result) and the average of the 3 measurements will be used.
- Blood pressure:
- Analysis
- Primary endpoints will be systolic and diastolic pressure for the week prior to and immediately after 6 weeks of training.
- Secondary endpoints will be:
- maximum inspiratory pressure, expiratory pressure, and inspiratory volume, and pulse for the week prior to and immediately after 6 weeks of training.
- All primary and secondary endpoints every two weeks during training
- If any significant effects are observed, I will continue tracking for an additional 6 weeks to see if the effect persists.
- Effects will be considered of significant magnitude if a reduction of at least 3 mmHg is observed with a p-value of < 0.05.
These experiments started ~1 week ago, though I haven’t looked at the data. I expect to have the first interim analysis in 2 weeks and the full study results in 7 weeks.
– QD
