Is There An Adrenaline Response To Exercise?

The answer is no- there is not an adrenaline response to exercise. The adrenaline response is also known as the fight or flight response, and it is activated by the amydala, which is part of the limbic system of the brain. The amygdala senses fear, anxiety, and stressors. When the amygdala is triggered by anxiety and stressors, it in turn activates the sympathetic nervous system via the locus coeruleus, and also activates the HPA axis (hypothalamic-pituitary-adrenal axis). The sympathetic nervous system then triggers various body organs, such as the heart, and it increases the heart beat and contraction. The sympathetic nervous system also activates the adrenal medulla, and it subsequently releases epinephrine (adrenaline) into the bloodstream, acting as a circulating hormone in the bloodstream and further adding to the sympathetic nervous system response of increasing heart rate, widening the bronchioles in the lungs, increased sweating, increased muscle tension, and blood shunting from the skin, digestive system, and reproductive system to the muscles.

The sympathetic nervous system innervates organs such as the heart, and the main neurotransmitter is norepinephrine. When the sympathetic nervous system is activated, the sympathetic nerves release norepinephrine into the synaptic cleft, and excess norepinephrine is absorbed into the bloodstream. So circulating norepinephrine is an indication of sympathetic nervous system activation, and circulating epinephrine is an indication of adrenal medulla activation (Kvetnansky et al., 2009).

It has been shown that exercise training is associated with decreased sympathetic nervous system activation (Blanchard et al., 2006) and regular moderate exercise can decrease stress (de Lira et al., 2008). It has also been shown that the enzymes used to produce norepinephrine and epinephrine, tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH), is increased when one is exposed to chronic psychosocial stressors, while TH and DBH are brought back down to normal levels when one is exposed to daily, 20-minute treadmill exercise (Gavrilovic et al., 2012).

In conclusion, daily, moderate exercise is not associated with an adrenaline response- it actually attenuates it, especially when stressors are activating the adrenaline response. The take home message is that daily, moderate exercise can help to reduce stress, which is mediated by the reduction of the adrenaline response.

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Kvetnansky R, Sabban EL, Palkovits M (2009) Catecholaminergic systems in stress: structural and molecular genetic approaches. Physiol Rev 89:535–606. Blanchard BE, Tsongalis GJ, Guidry MA, LaBelle LA, Poulin M, Taylor AL, Maresh CM, Devaney J, Thompson PD, Pescatello LS (2006) RAAS polymorphisms alter the acute blood pressure response to aerobic exercise among men with hypertension. Eur J Appl Physiol 97:26–33. de Lira CA, Vancini RL, Ihara SS, da Silva AC, Aboulafia J, Nouailhetas VL (2008) Aerobic exercise affects C57BL/6 murine intestinal contractile function. Eur J Appl Physiol 103:215–223. Gavrilovic L, Spasojevic N, Dronjak S (2012) Modulation of catecholamine-synthesizing enzymes in adrenal medulla and stellate ganglia by treadmill exercise of stressed rats. Eur J Appl Physiol 112(3):1177-82.

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