by Joe Giandonato, MBA, MS, CSCS
Myths involving strength training still circulate like small faced US denominations. In order to eliminate the negative stigma associated with strength training, the medical and allied health communities need to be educated on its wide ranging benefits and practical applications. The multimodal practice of strength training comprises the incorporation of exercises performed with one’s bodyweight, which include calisthenics and isometrics; external resistance utilizing free weights, such as barbells, dumbbells, and kettlebells; plate-loaded, selectorized, hydraulic machinery, and resistance bands. Strength training yields marked improvements in body composition, increases lean body mass, including gains in muscle and bone mass, optimizes endogenous hormonal secretion and sensitivity, improves components critical to survival, activities of daily living, and sport, which include: strength, strength-endurance, power, agility, and speed.
However, there is considerable evidence showing that strength training yields cardioprotective effects. Chronic adaptations to strength training include: reductions in systolic blood pressure (1,7), diastolic blood pressure (1,5), and mean arterial pressure (1,5). In conjunction with cardiorespiratory fitness training, strength training elicits improvements in skeletal muscle metabolism, increases capillary and mitochondrial density, improves angiogenesis (3), vascularization (4), and reduces oxidative stress. Long term strength training has been shown to lessen aortic stiffness (6). Consequent to the enlargement of capillary and mitochondrial structures is a greater capacity to generate and transport ATP, in turn enhancing the body’s bioenergetic capacity to meet biomechanical demands. Strength trained individuals possess streamlined myocardial functioning evidenced by higher stroke volumes and proportionally lower heart rates stemming from increased plasma volume, an adaptation of vigorous exercise. Strength training has also been shown to boost high density lipoprotein (HDL) cholesterol levels (8), a chief negative risk factor in the development of cardiovascular disease.
To better understand the adaptations which occur as a result of strength training, the process and subsequent responses of cardiovascular functioning need to be analyzed.
During activity, the cardiovascular system undergoes two distinct changes. First, the cardiovascular system must provide sufficient oxygen enriched blood to working muscles to meet the demands of the activity. Blood is shunted away from visceral organs and driven to the skeletal muscles which are performing mechanical work. In high intensity exercise, such as strength training, as much as 80% of all blood ejected from the heart is delivered to skeletal muscle. Second, the demands of activity evoke a vasodillatory response leading to reduced peripheral resistance, thus enhancing blood flow to working muscles. In spite of these hemodynamic processes, rising cardiac output causes an increase in systolic blood pressure. Exercise conducted at circa maximal intensities, such as vigorous strength training, may cause systolic pressure to approach and/or exceed values of 200-300mm Hg or greater. As many are led to believe, the benefactor of strength training isn’t just the musculoskeletal system, the heart is working Strength training activities elevate blood pressure as muscular contractions impede intramuscular blood flow, consequently increasing peripheral resistance. As such, intensive strength training is generally contraindicated for elderly individuals and those suspected having or suffering from cardiovascular disease.
A study involving bodybuilders and non-bodybuilder college students revealed similar resting systolic and diastolic blood pressures and comparable peri exercise values (2). Studies involving isotonic and isometric strength training exercise have shown decreases in blood pressure, however, it has been suggested that dynamic strength training exercise conducted at moderate intensities elicit favorable cardiovascular responses, both acutely and chronically (2,3,4,6). Strength training is an appropriate option for those with functional movement capacity which disallows longer duration cardiorespiratory fitness training from being conducted. It is also far more time efficient, a perfect alternative for those with hectic schedules.
In spite of the volumes of scientific literature and countless studies which support strength training as a viable modality in preventing and treating cardiovascular disease, it remains in the shadow of cardiorespiratory fitness programs based on endurance training protocols. A majority of medical and allied health professionals as well as the general public shortsightedly embrace endurance training protocols, which include jogging, walking, and biking as the preferred, if not the sole option in addressing cardiovascular health.
Individuals who are new to strength training may be deficient in motor control and relative strength. Overweight individuals may be better suited for machine based training in order to provide a rich metabolic stimulus, one that is not interfered with a lack balance or proprioception, which is common in novice exercisers. A strength training program needs to be designed based on the specifications, goals, and needs of the individual and should entail progressions in load, volume, intensity, frequency, and movement complexity. The generic recommendation calls for two non-consecutive strength training sessions per week, however, they may be performed more frequently if time and recovery permits and as goals and needs warrant.
- Carlson, D.J., Dieberg, G., Hess, N.C., Millar, P.J., & Smart, N.A. (2014). Isometric exercise training for blood pressure management: A systematic review and meta-analysis. Mayo Clinic Proceedings, 89, 327-334.
- Colliander, E.B., Tesch, P.A. (1988). Blood pressure in resistance-trained athletes. Canadian Journal of Sport Science, 13, 31-34.
- Gasiorowski, A., Dutkiewicz, J. (2013). Comprehensive rehabilitation in chronic heart failure. Annals of Agricultural and Environmental Medicine, 20, 606-612.
- Longhurst, J.C., Stebbins, C.L. (1997). The power athlete. Cardiology Clinics, 15, 413-429.
- Millar, P.J., McGowan, C.L., Cornelissen, V.A., Araujo, C.G., & Swaine, I.L. (2014). Evidence for the role of isometric exercise training in reducing blood pressure: potential mechanisms and future directions. Sports Medicine, 44, 345-366.
- Morra, E.A., Zanigueli, D., Rodrigues, S.L., El-Aouar, L.M., Lunz, W., Mill, J.G., & Carletti, L. (2014). Long-term intense resistance training in men is associated with preserved cardiac structure/function, decreased aortic stiffness, and lower central augmentation pressure. Journal of Hypertension, 32, 286-293.
- Mostarda, C.T., Rodrigues, B., de Cxu Moraes, O.A., Moraes-Silva, I.C., Arruda, P.B., Cardoso, R., Scapini, K.B., Dos Santos, F., De Angelis, K., & Irigoyen, M.C. (2013). Low intensity resistance training improves systolic function and cardiovascular autonomic control in diabetic rats. Journal of Diabetes and its Complications. [Epub ahead of print].
- Rossow, L.M., Fahs, C.A., Thiebaud, R.S., Loenneke, J.P., Kim, D., Mouser, J.G., Shore, E.A., Beck, T.W., Bemben, D.A., & Bemben, M.G. (2014). Arterial stiffness and blood flow adaptations following eight weeks of resistance exercise training in young and older women. Experimental Gerontology, 53, 48-56.
- Ullrich, I.H., Reid, C.M., & Yeater, R.A. (1987). Increased HDL-cholesterol levels with a weight lifting program. Southern Medical Journal, 80, 328-331.
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