Why cardio?

Like many things in life, fitness trends swing in roundabouts and no one is ever sure which is the right form of exercise to be doing. Some people fear lifting weights because they’ll be bulky, whilst others neglect cardiovascular exercise as they’re concerned that their muscles will disappear. Ultimately, both forms of exercise are vital to your health, and it’s beneficial if you can incorporate both into your training. This blog post focusses on cardiovascular exercise and will be followed in the upcoming weeks by a sister post on resistance training so that you can understand why it’s good to use both methods of training.

Cardiovascular exercise, often referred to as cardio, is anything that gets your heart rate up with the purpose of improving your health and fitness. Whilst resistance training can do this, its purpose is to train muscles, whereas cardio trains your heart and lungs as it were. The types of activities covered by cardio are typically those which are dynamic, have a low-resistance and involve repetitive movements; think things like running, cycling, swimming and walking. Cardio can be split into two categories depending on the intensity and therefore the energy systems that your body uses to carry out the activity. Aerobic exercise uses oxygen to produce ATP, which is broken down to release energy. Aerobic exercise doesn’t produce any lactate, which is the substance that is responsible for the achy feeling you get when you exercise. With aerobic exercise, your heart rate won’t exceed 60% of it’s maximum, so you don’t fatigue quickly and can keep going for much longer periods of time. Anaerobic exercise uses either the lactate or phosphate energy systems and occurs at a higher intensity. These systems are used for much shorter bursts of exercise and cause fatigue very quickly but are beneficial to use sometimes as they challenge your heart and lungs to work much harder. Both aerobic and anaerobic forms of exercise are beneficial, and it’s recommended by the NHS for individuals to get in 150 minutes of moderate (think walking) or 75 minutes of intense (e.g. running) cardiovascular exercise each week.

Unsurprisingly, given its name, cardiovascular exercise has huge benefits on the cardiovascular system, which comprises your heart and circulation. Studies have shown that 75% of individuals with high blood pressure (hypertension) achieved a beneficial decrease in blood pressure with exercise, and low-intensity aerobic exercise was the most helpful form of exercise in enabling this (Hagberg et al., 2000). Reducing high blood pressure is enormously beneficial, with reductions in the risk of stroke, heart attacks and cardiovascular deaths achieved as blood pressure is lowered (Katsanos et al., 2016). Anaerobic, higher intensity exercise is also beneficial as it produces a substance called CNP which acts on the blood vessels to reduce blood pressure (Lumsden et al., 2010). Low intensity exercise can be beneficial into old age through reducing the risk of death from cardiovascular disease (CVD); elderly men who walked less than 0.25 miles every day had a 2-fold greater risk of dying from CVD compared to those who walked 1.5 miles each day (Hakim et al., 1999). Furthermore, being able to walk or jog a total of 15-20 miles each week led to an increase in the amount of HDL and a decrease in the amount of triglycerides in the bloodstream, which is beneficial as HDL protects the artery walls from inflammation and transports cholesterol to the liver to allow it to be removed from the body, whilst high triglycerides can contribute to atherosclerosis and blocking of the arteries (Durstine et al., 2001).

Cardio has positive impacts that extend beyond the cardiovascular system, however. It has plentiful metabolic benefits, meaning that it helps the way in which our bodies process substances to produce the energy required for everyday function. Exercise induces mitochondrial biogenesis, which is produces mitochondria, the organelles which enable us to carry out aerobic respiration to produce ATP from the food that we consume. As the quality and number of mitochondria decreases with age, it’s vital that older adults in particular carry out regular cardiovascular exercise with increasing intensity over time, as this has been found to increase the function of mitochondria by up to 50% (Menshikova et al., 2006). When it comes to fat loss, aerobic exercise has been found to have greater effects than calorie restriction through increasing your total daily energy expenditure, in particular the energy expended by the thermal activity of exercise (Donnelly et al., 2013). This type of exercise can also be highly beneficial in helping type 2 diabetics to control their blood sugars, as one low intensity exercise session can increase insulin sensitivity and glycaemic control, with these benefits lasting until the next day (Newsom et al., 2013). Combined with the opportunity to increase weight loss, this makes exercise extremely beneficial for diabetics, as the skeletal muscle is the primary site of glucose uptake, and this uptake is greater in muscles that are actively contracting (Richter et al., 2001).

The effects of cardiovascular exercise are not only physical; there are multiple psychological benefits as well. Studies have found that the effects of regular cardiovascular exercise are comparable to psychotherapy and medication for mild-moderate depression, and 12 weeks of aerobic training had benefits on individuals’ self-esteem, mental health, anxiety and insomnia (Craft et al., 2012). These effects are attributed to many theories, including the endorphin and monoamine hypotheses. The endorphin hypothesis proposes that exercise causes the release of chemicals caused endorphins which help promote a feeling of positivity, whilst the monoamine hypothesis states that exercise causes the release of neurotransmitters such as serotonin and dopamine in the brain. This is beneficial in improving depressive symptoms, as these neurotransmitters are typically depleted in those suffering with depression (Craft & Perma, 2004). As such, mild exercise could be considered a valuable tool for helping individuals manage mental health conditions.

Why Cardio?

The above benefits are by no means an exhaustive list of the positive effects that cardiovascular exercise can have on our health, but I hope that it goes some way to convincing you that cardio is good for a huge variety of reasons and individuals. However, you should always check with your doctor before you start introducing any form of exercise into your regime, particularly if you have or someone in your family has any pre-existing health conditions. If you’re new to cardiovascular exercise, make sure to build up gently, perhaps by incorporating intervals of light jogging into a walk. To progress your fitness you can increase the intensity or the duration of the exercise each week and you’re bound to notice improvements soon. Cardio is certainly something that I recommend AtHome GetFit clients, and, like everything else, it’s tailored to each client’s individual requirements. With so many different forms of cardiovascular activity, you’re bound to find something that suits you.

References:

Craft, L. L., & Perna, F. M. (2004). The benefits of exercise for the clinically depressed. Primary Care Companion to the Journal of Clinical Psychiatry, 6(3), 104-111. doi:10.4088/pcc.v06n0301

Craft, L. L., Vaniterson, E. H., Helenowski, I. B., Rademaker, A. W., & Courneya, K. S. (2012). Exercise effects on depressive symptoms in cancer survivors: A systematic review and meta-analysis. Cancer Epidemiology, Biomarkers & Prevention : A Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology, 21(1), 3-19. doi:10.1158/1055-9965.EPI-11-0634 [doi]

Donnelly, J. E., Honas, J. J., Smith, B. K., Mayo, M. S., Gibson, C. A., Sullivan, D. K., et al. (2013). Aerobic exercise alone results in clinically significant weight loss for men and women: Midwest exercise trial 2. Obesity (Silver Spring, Md.), 21(3), E219-E228. doi:10.1002/oby.20145

Durstine, J. L., Grandjean, P. W., Davis, P. G., Ferguson, M. A., Alderson, N. L., & DuBose, K. D. (2001). Blood lipid and lipoprotein adaptations to exercise: A quantitative analysis. Sports Medicine (Auckland, N.Z.), 31(15), 1033-1062. doi:311502 [pii]

Hagberg, J. M., Park, J. J., & Brown, M. D. (2000). The role of exercise training in the treatment of hypertension: An update. Sports Medicine (Auckland, N.Z.), 30(3), 193-206. doi:10.2165/00007256-200030030-00004 [doi]

Hakim, A. A., Curb, J. D., Petrovitch, H., Rodriguez, B. L., Yano, K., Ross, G. W., et al. (1999). Effects of walking on coronary heart disease in elderly men: The honolulu heart program. Circulation, 100(1), 9-13. doi:10.1161/01.cir.100.1.9 [doi]

Katsanos Aristeidis, H., Angeliki, F., Efstathios, M., Spyridon, D., John, P., Alexandra, F., et al. (2017). Blood pressure reduction and secondary stroke prevention. Hypertension, 69(1), 171-179. doi:10.1161/HYPERTENSIONAHA.116.08485

Lumsden, N. G., Khambata, R. S., & Hobbs, A. J. (2010). C-type natriuretic peptide (CNP): Cardiovascular roles and potential as a therapeutic target. Current Pharmaceutical Design, 16(37), 4080-4088. doi:10.2174/138161210794519237

Menshikova, E. V., Ritov, V. B., Fairfull, L., Ferrell, R. E., Kelley, D. E., & Goodpaster, B. H. (2006). Effects of exercise on mitochondrial content and function in aging human skeletal muscle. The Journals of Gerontology.Series A, Biological Sciences and Medical Sciences, 61(6), 534-540. doi:10.1093/gerona/61.6.534

Newsom, S. A., Everett, A. C., Hinko, A., & Horowitz, J. F. (2013). A single session of low-intensity exercise is sufficient to enhance insulin sensitivity into the next day in obese adults. Diabetes Care, 36(9), 2516-2522. doi:10.2337/dc12-2606

Richter, E. A., Derave, W., & Wojtaszewski, J. F. (2001). Glucose, exercise and insulin: Emerging concepts. The Journal of Physiology, 535, 313-322. doi:10.1111/j.1469-7793.2001.t01-2-00313.x