Tag Archives: cardiovascular

Not Everyone Breathes While they Sleep: The Dangers of Sleep Apnea

You might think that breathing in our sleep should come naturally – if breathing and sleeping are both physiologically necessary, then we must be able to do them simultaneously right? Unfortunately, almost a quarter of middle-aged American men and nearly 10% of women suffer from sleep apnea, a chronic condition characterized by repeatedly stopping breathing while sleeping. The clinical symptoms seem rather benign – snoring, sleepiness, fatigue during the day or other issues sleeping. However, by far the most dangerous aspect of this disease is that it puts patients at increased risk of high blood pressure, stroke, coronary heart disease, as well as occupational and/or automobile accidents. Over the last several decades, a variety of therapy options have been studied to treat this condition, ranging from drugs to masks to surgery.

One of the earliest documented therapy options is using protriptyline to treat obstructive sleep apnea. Protriptyline is an anti-depressant drug that was used for its ability to clear airway obstructions during sleep; however, it did not gain significant popularity due to its adverse effects including cardiac complications and limited demographics for whom it would be an appropriate treatment.

The next treatment discussed was altering sleep positions for patients suffering from sleep apnea. A seemingly simple idea, a study determined that laying on the back significantly increased the severity of sleep apnea. Interestingly, the difference in severity between back and side sleeping positions was most noticeable in healthy, non-obese patients. The authors believe that lying on the back causes tissues of the throat to obstruct the trachea and prevent smooth airflow during breathing, as shown in the image below, which would explain why obesity can exacerbate sleep apnea.

Diagram of airflow obstruction through mouth and throat
Photo by Habib M’Henni on Wikimedia Commons.

Multiple non-invasive devices were also studied, including oral appliances, sleep posture alarms, and positive airway pressure devices. Oral appliances can either protrude the lower jaw or restrain the tongue; both aim to restructure the upper airway (mouth, trachea, etc.). Sleep posture alarms were suggested to train patients to sleep on either side, rather than on their backs. Positive airway pressure devices (Bi-PAP, CPAP) are the most commonly used treatment for sleep apnea currently; they maintain a consistent air pressure flowing into the mouth to ensure the airways do not collapse during sleep.

Man sleeping while using CPAP machine
Photo by ApneaMed

The final treatment studied was nocturnal supplemental oxygen (NSO), which involves increasing the concentration of oxygen in the air inhaled while sleeping. However, a study comparing use of a CPAP with use of NSO found that CPAP treatment was far more effective at decreasing the patients’ blood pressure and still proved effective in patients already taking blood pressure medication.

Overall, the best method for treating sleep apnea is dependent on the patient and his or her underlying conditions. Changes in sleep posture could greatly enhance the sleep quality of a moderate case of sleep apnea; CPAP would be ideal for someone who can easily tolerate the mask and does not frequently move in his or her sleep. Each of these demographics makes it difficult to define one optimal solution for treating sleep apnea, but the variety of available treatment options provides hope for those patients who suffer from this chronic illness.

Walk [Under] Water: The Benefits of Underwater Running

Just because you can’t walk on water doesn’t mean you shouldn’t run under it!

Aqua-jogging. Hydro-running. Water-treadmills. Have you ever heard some combination of these terms and wondered what the hype is?

Running underwater offers benefits for people throughout their fitness journey. Underwater running has proven useful for a variety of focuses, including recovery after injury, cross training, and even improved gait. This article includes a video showing a Runner’s World coach tries out a Hydrotrack and discusses some of the benefits!

So, why does it work?

Three basic water properties: hydrostatic pressure, buoyancy, and viscosity.

Hydrostatic pressure is the force that the water exerts on a submerged point. Hydrostatic pressure acts all around the point. However, since hydrostatic pressure is proportional to the weight of liquid above the point, it increases with increased water depth. This means that your feet would experience greater hydrostatic pressures than your knees. While running, this pressure helps support your body and decrease impact forces. In addition to helping prevent injuries through a decreased risk of falling, it also helps decrease swelling and promote cardiovascular health. This article talks about the specifics of pressure with swelling and the cardiovascular system.

Diagram showing hydrostatic forces. Magnitude of the hydrostatic force is larger as it goes deeper below the surface.
Hydrostatic pressure acts on all sides of a point. The pressure increases with depth. Created in Microsoft PowerPoint.

Buoyancy is the hydrostatic force applied to an object with volume (rather than just a point). Since they are at the same depth, all the horizontal forces cancel out. Since the bottom of the object is deeper than the top, the net buoyant force on the object pushes up. The difference between the buoyant force and the weight of the object submerged determines if the object will rise, sink, or stay in place. Thus, the more submerged a person is, the more of their weight is supported. This research article explains how this support can help make gait analysis more effective to further prevent injury. When water reaches the person’s navel, 50% of their weight is supported. This weight bearing capability of water decreases forces on joints and can even help improve range of motion. This allows physical therapy to begin sooner and, overall, take less time out of the patient’s normal routine. This allows shorter rehabilitation times without sacrificing quality of care or recovery.

 

Diagrams showing how the hydrostatic force varies around the submerged object due to depth. The side forces cancel out at equal depth leaving a net buoyant force acting upward against the downward force of the object weight.
Buoyant forces cancel out on the sides leading to the second image showing the net buoyant force and the weight of the object. Created in Microsoft PowerPoint.

Viscosity is a fluid property that affects the resistance that an object encounters during motion. In the case of underwater running, viscosity explains why you move significantly slower in water than on land. It also can offer resistance up to 15 times the amount of resistance on land. Forcing your limbs through the water strengthens muscles that are not typically used out of the water and even burns more calories!

As noted above, viscosity can help strengthen muscles as shown in this study on deep water running (DWR) in a community of elderly women shows how viscosity affects overall strength training. It showed that the women who participated in DWR increased their muscle strength (measured through power) and performed better in various tests, including ones that involved sitting down and getting up. The study showed that deep water running helped to mitigate some of the negative muscular effects of aging.

Overall, running underwater offers some great benefits. The basic properties of water (hydrostatic pressure, buoyancy, and viscosity) provide scientific background for why hydro-running provides benefits for all.