This article is dedicated to all the bros that swear by never even making eye contact with a treadmill, let alone approaching and utilizing one. The necessity of a cardiovascular component to a strength training program has long been a controversy among gym goers of varying goals and skill levels. The reality is that, while cardiovascular health may not significantly impact muscle strength or size, it is a crucial aspect of overall health and well-being and should be treated as such. So, unfortunately for the many eager eyes that may cross this article, we won’t necessarily breakdown any barriers or crush any myths about the necessity of cardio training. You’ve just gotta do it, and here’s why.
Cardiovascular health simply refers to the vitality of both our heart and all of our blood vessels taxed with the job of delivering oxygen-rich blood to our body and returning oxygen-depleted blood to our heart and ultimately, lungs. This system is essentially our personal life line – complications can severely increase risk for cardiac-related events and even premature death. Heart disease is typically one of the top three “killers” around the world alongside cancer and accidents. Honestly I’m bummed that I have to continue writing this article; the above information should be enough for you to hop on some cardio equipment or take a walk once in a while, but let’s forge on since we’re already here.
As a stereotypical gym bro myself, I have no doubt many gym-goers are interested to learn more about how resistance training may affect our cardiovascular system and if we can rely on those effects alone for heart health. While not studied as extensively as endurance training, strength training does seem to have some benefits for cardiovascular health. One of the main benefits of strength training is that it can reduce blood pressure (3,12,17). This phenomenon may be due to the acute increase in systolic blood pressure while lifting heavy loads (8). This acute increase can potentially improve the elasticity of our blood vessels which can lower blood pressure and reduce the risk of stroke and heart attack.
Strength training programs have also shown to be beneficial to those suffering from chronic heart failure, a disease that often results in a severe decrease in muscular strength among other serious side-effects (1,2,4,5,15,17). The benefits are mainly derived from an overall increase in muscular strength (15) but have major implications for heart health. When maximal muscle strength is increased, every submaximal exercise or activity becomes easier. In fact, chronic heart failure patients exposed to resistance training have been shown to improve several facets of cardiovascular fitness and improve their ability to maintain a steady-state workload at a lower heart rate through strength training alone (2,12,15).
Using chronic heart failure patients isn’t exactly a direct comparison for most of our readers, so let’s examine how strength training can affect heart health in healthy populations and even strength athletes.
One study examined the effects of resistance training vs endurance training on common cardiovascular health markers in young, healthy men. While most improvements were specific to prescribed training styles, it’s very interesting to note that after a 6-week detraining period, the group that performed strength training maintained almost all of their gains compared to the endurance group whose performance returned to pre-training levels. The strength training group also significantly lowered blood pressure when compared to the endurance group (17). Both of these factors show the importance of strength training on cardiovascular health, but it’s important to point out that researchers haven’t found strength training to directly improve the hemodynamic qualities (blood pumping abilities) of the heart (1,3,4,5,15,16,17).
Now let’s move on to the hearts of well-trained athletes. The Morganroth Hypothesis is a well-known and well-researched subject when it comes to the long term effects of training. Essentially this hypothesis states that there are two types of hypertrophy or growth that occur in the heart due to training – eccentric and concentric (13). Eccentric hypertrophy occurs when both the left ventricle and left ventricle cavity enlarge. This improves heart strength and the ability to pump blood to the rest of the body, and also increases the amount of blood you can pump per beat. This type of hypertrophy is most commonly seen in endurance trained athletes.
The other type is concentric hypertrophy which occurs when the left ventricle and left ventricle wall enlarge, but the cavity size remains about the same. This increases the strength of the heart, but blood flow doesn’t change much since the ventricle doesn’t fill any better than it used to (13). Originally this type of hypertrophy was thought to be common in strength athletes but in recent times this hypothesis has been challenged by studies refuting the presence of concentric hypertrophy in strength athletes or trainers (6,8,9,10,11,14,17,18). There needs to be more verification on the topic as most heart-related exercise studies are too short-term or only involve endurance training.
What does all of this mean for the typical gym bro, then? Left ventricular hypertrophy and heart growth in general have long been blamed for causing a good portion of cardiac complications but the problem is that the majority of these symptoms are seen in sedentary or obese individuals with high blood pressure (7). High blood pressure may cause a similar concentric increase in heart mass like strength athletes are thought to exhibit (11) but the difference is that there’s no health benefits associated with that increase in mass. Furthermore, the increases in athlete heart size also seem to only be elicited by high level athletes who have consistently trained for several years (18). In addition, these athletes reap the benefits of a much improved cardiovascular system when compared to hypertensive individuals. Novice and intermediate trainers don’t seem to exhibit any heart hypertrophies following training programs (9,10,17).
Ultimately, strength training seems to improve blood pressure, cholesterol levels, and blood glucose levels (2,3,12,15,17), all of which have important implications to overall cardiovascular health and function. But, remember that strength training doesn’t appear to improve things like heart contractility, the amount of blood pumped per beat, or even the percentage of blood in the heart that actually gets pumped out (1,4,5,16).
That’s where the necessity of adding cardio to your training regimen comes in. To fully improve the health and function of your cardiovascular system, you need a combination of strength and endurance training. Yes, cardio is boring and lame. But at the end of the day, your health and well-being are just as important to those around you as they are to you, and you owe it to these people to live a strong and healthy life.
- Adamopoulos, S., et. al. (1993). Physical training improves skeletal muscle metabolism in patients with chronic heart failure. Journal of the American College of Cardiology, 21(5), 1101-1106.
- Beckers, P. J., Denollet, J., Possemiers, N. M., Wuyts, F. L., Vrints, C. J., & Conraads, V. M. (2008). Combined endurance-resistance training vs. endurance training in patients with chronic heart failure: a prospective randomized study. European Heart Journal, 29(15), 1858-1866.
- Cauza, E., Hanusch-Enserer, U., Strasser, B., Ludvik, B., Metz-Schimmerl, S., Pacini, G., … & Dunky, A. (2005). The relative benefits of endurance and strength training on the metabolic factors and muscle function of people with type 2 diabetes mellitus. Archives of Physical Medicine and Rehabilitation, 86(8), 1527-1533.
- Coats, A. J. S. (1993). Exercise rehabilitation in chronic heart failure. Journal of the American College of Cardiology, 22(4 Supplement 1), A172-A177.
- Coats, A. J. S., Adamopoulos, S., Meyer, T. E., Conway, J., & Sleight, P. (1990). Effects of physical training in chronic heart failure. The Lancet, 335(8681), 63-66.
- Falkel, J. E., Fleck, S. J., & Murray, T. F. (1992). Comparison of central hemodynamics between powerlifters and bodybuilders during resistance exercise. The Journal of Strength & Conditioning Research, 6(1), 24-35.
- Ganau, A., et. al. (1992). Patterns of left ventricular hypertrophy and geometric remodeling in essential hypertension. Journal of the American College of Cardiology, 19(7), 1550-1558.
- Haykowsky, M. J., Dressendorfer, R., Taylor, D., Mandic, S., & Humen, D. (2002). Resistance Training and Cardiac Hypertrophy. Sports Medicine, 32(13), 837-849.
- Haykowsky, M., Humen, D., Teo, K., Quinney, A., Souster, M., Bell, G., & Taylor, D. (2000). Effects of 16 weeks of resistance training on left ventricular morphology and systolic function in healthy men> 60 years of age. The American Journal of Cardiology, 85(8), 1002-1006.
- Haykowsky, M., Taylor, D., Teo, K., Quinney, A., & Humen, D. (2001). Left ventricular wall stress during leg-press exercise performed with a brief Valsalva maneuver. Chest, 119(1), 150-154.
- Haykowsky, M. J., & Tomczak, C. R. (2014). LV hypertrophy in resistance or endurance trained athletes: the Morganroth hypothesis is obsolete, most of the time. Heart, 100, 1225-1226
- Kraemer, W. J., Ratamess, N. A., & French, D. N. (2002). Resistance training for health and performance. Current Sports Medicine Reports, 1(3), 165-171.
- Morganroth, J., Maron, B. J., Henry, W. L., & Epstein, S. E. (1975). Comparative left ventricular dimensions in trained athletes. Annals of Internal Medicine, 82(4), 521-524.
- Pelliccia, A., Spataro, A., Caselli, G., & Maron, B. J. (1993). Absence of left ventricular wall thickening in athletes engaged in intense power training. American Journal of Cardiology, 72(14), 1048-1054.
- Pu, C. T., et. al. (2001). Randomized trial of progressive resistance training to counteract the myopathy of chronic heart failure. Journal of Applied Physiology, 90(6), 2341-2350.
- Shephard, R. J. (1997). Exercise for patients with congestive heart failure. Sports Medicine, 23(2), 75-92.
- Spence, A. L., et. al. (2011). A prospective randomised longitudinal MRI study of left ventricular adaptation to endurance and resistance exercise training in humans. The Journal of Physiology, 589(22), 5443-5452.
- Utomi, V., et. al. (2013). Systematic review and meta-analysis of training mode, imaging modality and body size influences on the morphology and function of the male athlete’s heart. Heart, 99(23), 1727-1733.
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