Tag: cardiovascular

An Exploration Into The Growth Of The Heart As A Result Of Certain Exercise

Have you ever wondered what happens to your heart when you begin to consistently exercise? How does the heart change and why? Well, the answer may not be very complicated.

During intense exercise, our heart is put under stress as it has to rapidly pump blood throughout the body. The heart often responds to this by increasing its size, but it does not do this like our other muscles. The heart has to add mass to its existing cells instead of adding new cells as we only have a limited amount of cardiac muscles; the amount we are born with is all we have. The health of our hearts is important. In the US, heart disease and injury are the number 1 cause of death. So, it is in our best interests to learn more about our health so as to minimize our risks of heart-related ailments.

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Work Smarter Not Harder!

We have all likely heard the saying, “Work smarter not harder.” While this is generally referenced in an academic setting, it is also very applicable in athletics! One of the benefits to being a runner is that it’s a sport people can participate in at any age and nearly anywhere. Unfortunately, however, anywhere from 65-80% of runners get injured in a given year. A large portion of these injuries are related to overuse.

Recovery

It’s a common misconception amongst runners that the harder you push during your runs, the faster you will be on race day. As a result, the majority or runners overdo their “easy” days. This leaves their legs fatigued and tired going into workouts and races. The majority of fitness is gained during a “workout” day, so overdoing easy days reduces your ability to push hard on workout days. To truly maximize their potential, an athlete must focus on their recovery. Recovery is a broad term that includes a variety of factors such as sleep quality, nutrition, and post run stretching and rehab exercises. Monitoring your heart rate is one way to manage your recovery, reduce overtraining, and limit bone stress injuries. 

Managing Heart Rate

Photograph of a smartwatch reading heart rate
Photo by Brooke Trossen

Heart rate monitors are used by runners to train smarter and ultimately race faster. Resting heart rate and heart rate recovery measurements are indications of how an athlete’s body is responding to stress and exercise long term. Heart rate measurements can be used to guide what the pace of a run should be. Heart rate measurements are commonly separated into five “zones.” On different days of the week and stages in a training cycle, a run should fall into the different zones. It may be beneficial for an athlete to also have a general idea of what their heart rate is at a given running pace. If their heart rate is more than 7 beats per minute above the usual rate, it may be a sign that the athlete has not fully recovered from their last training session and that they should continue with easy days until having another intense session. This is also important for runners since the weather conditions can greatly affect the difficulty of a run. Rather than having a goal pace for a given day, it is better to have a goal range of heart rates to make sure the run is best serving the athletes body. This will enable an athlete to get the appropriate effort in whether it is 70° and sunny or 30° with 20 mph winds.

Monitoring heart rate after exercise can also accurately indicate whether or not an athlete is fully recovered. It is important to note that your heart rate fluctuates, so it is more valuable to observe general trends than it is to overanalyze specific data points. A morning heart rate 5 beats per minute above your usual heart rate may be indicative that your body needs more rest or that you are getting sick. The image below shows a chart with ranges of resting heart rates depending on gender and age.

Chart of healthy resting heart rates for men and women with varying ages.
Photo by Jeremy on Agelessinvesting.com

Minimizing Bone Stress Injuries

Photograph of a stress reaction in the femur of a female runner
Photo by Brooke Trossen

Building a training plan with runs in a variety of zones will help limit overtraining and make the development of overuse injuries less likely. A bone stress injury (BSI) is defined as the inability of a bone to withstand repetitive loading. There are varying degrees of bone stress injuries from stress reactions to complete bone fracture. When performing repetitive motions such as running, micro-cracks form in your bone. These micro-cracks are actually healthy because loading your bones makes them stronger. In the process of remodeling, the micro-cracks are healed. Generally, additional remodeling units can be recruited in response to increase loads. The increase in remodeling units present, decreases the amount of bone mass. This results in a decrease in the ability for the bone to absorb energy and an increase in the number of cracks formed. When insufficient time is given for remodeling, the micro-cracks will begin to accumulate and stress reactions and fractures will form. A stress reaction in the right femur of a female runner is shown in the image above. The white highlights represent inflammation in the bone. 

Although overuse injuries are very common in runners, research shows that the use of heart rate monitors can help regulate recovery and positively influence training plans to limit overtraining. 

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.

Scleroderma and Raynaud’s Phenomenon: Cold Weather’s Influence on Skin

Anyone who is familiar with winters that are mainly at temperatures in single digit range knows how crucial gloves are to surviving the tough, frigid weather. If one was to go outside without them, their hands become extremely pale (or sometimes almost blue) and, once back inside, take a bit of time to get back to normal. It’s a tough life, I know, but people with a scleroderma have an even harder time surviving the winter. What is scleroderma, you ask? Scleroderma is an autoimmune disease that causes skin and internal organs to thicken, and if that wasn’t tough enough, a good chunk of people with it also experience secondary Raynaud’s phenomenon, which is an exaggerated vasoconstriction of arterioles in response to cold weather and causes a drop in blood flow. The main, visible outcome from this disease is how the skin whitens and swells. Problems must ensue from the combination of thick skin and lack of blood flow to the extremities, right?

Raynaud's Phenomenon in ring finger
Thomas Galvin [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

Modified from Balbir-Gurman, Denton, Nichols, Knight, Nahir, Martin, and Black, Annals of Rheumatic Diseases 2002

With the thickening of skin, certain properties of skin will noticeably alter when a person has scleroderma. In a recent study, researchers from multiple backgrounds used a new suction device to compare mechanical properties of skin of patients with scleroderma and healthy patients. In the experiment, the researchers used a modified Rodnan skin score to observe skin involvement. This way of testing focuses on how easy it is to pinch skin and witness how it folds. The skin was tested on 3 parts of the body including back, forearm, and shoulder in order to see how the skin not only differs between patients, but to see how different areas have different properties due to activity and use of those parts of the body. To test the skin of the patients, the new suction device used, the BTC-2000, also proved beneficial due to its non-invasive nature that could be used more frequently to produce data. The biomechanical properties of skin depend greatly on the dermis, or skin thickness, due to the properties being derived from witnessing skin response to pressure and stress. The study that these researchers performed supported the idea that mechanical properties of skin are altered negatively when a patient has scleroderma. The major properties that were observed were less extensibility, stretchiness, and a larger resistance to stress.

So the struggle to go outside in the winter is even bigger for people with scleroderma. But in their case, the damage brought on by cold weather is greater and typically more permanent. Similarly, if this is how the disease influences the mechanical properties of the outer skin, the potential impact on internal organs is intriguing.

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.