Metabolic and endocrine response to exercise: sympathoadrenal integration with skeletal muscle

Abstract

Skeletal muscle has the capacity to increase energy turnover by w1000 times its resting rate when contracting at the maximum force/power output. Since ATP is not stored in any appreciable quantity, the muscle requires a coordinated metabolic response to maintain an adequate supply of ATP to sustain contractile activity. The integration of intracellular metabolic pathways is dependent upon the cross-bridge cycling rate of myosin and actin, substrate availability and the accumulation of metabolic byproducts, all of which can influence the maintenance of contractile activity or result in the onset of fatigue. In addition, the mobilisation of extracellular substrates is dependent upon the integration of both the autonomic nervous system and endocrine systems to coordinate an increase in both carbohydrate and fat availability. The current review examines the evidence for skeletal muscle to generate power over short and long durations and discusses the metabolic response to sustain these processes. The review also considers the endocrine response from the perspective of the sympathoadrenal system to integrate extracellular substrate availability with the increased energy demands made by contracting skeletal muscle. Finally, the review briefly discusses the evidence that muscle acts in an endocrine manner during exercise and what role this might play in mobilising extracellular substrates to augment the effects of the sympathoadrenal system.

Immunometabolic Responses after Short and Moderate Rest Intervals to Strength Exercise with and without Similar Total Volume

“…Metabolic stressors associated with resistance exercise result in an acute increase in systemic anabolic hormone concentrations and an inflammatory response (Ball, 2015). Acute bouts of moderate intensity exercise (70% of 1 repetition maximum—RM) have been shown to elevate post-exercise testosterone concentrations (Rietjens et al, 2015), stimulating protein synthesis, inhibiting protein degradation, and potentially promoting muscle hypertrophy (Vingren et al, 2010).…”

Experience of a Tertiary-Level Urology Center in the Clinical Urological Events of Rare and Very Rare Incidence. III. Psychourological Events: 1. Psychic Anuria

“…This latter assumption based on that the kidney is an organ of known endocrine functions [22], where there are newly discovered hormone-like proteins that exert multi-organ regulatory and protective functions involving the brain [23-25]. So, proposed reflexes or feedback pathways to the kidney based on the integrations among the body systems and functions could be warranted [18, 19]. Explanation of the normal blood biochemical values could be attributed to a hepatic function of consumption and elimination of these wastes.…”

The sedentary (r)evolution: Have we lost our metabolic flexibility?

“…Cortisol levels increase autonomously in the morning before awakening to provide preferentially glucose for the brain and fatty acids for skeletal muscles to support foraging behavior, mainly based on fat-consuming type 1 muscle fiber activity. Glucose represents the energy substrate for type 2 muscle fibers, necessary for survival in lethal fight-flight-situations 29, 68, 69 . While this can be considered a seldom event in Paleolithic times, today´s long-lasting psychosocial stress in an economically growth-driven sedentary environment leads to prolonged cortisol release, stimulating gluconeogenesis but without subsequent glucose clearance by skeletal muscles 70 .…”

“…Blood flow in muscles can increase from 1200 to 22,000 ml/min. In contrast, blood flow to organs such as the kidneys or the viscera, which are energetically neglected in acute danger situations, decreases significantly 69 . The interplay of SNS-derived catecholamines and the secretion of cortisol, delivered by the HPA-axis, mobilizes glycogen and fatty acids from storage organs (muscles, liver, fat tissue) to provide fuel for the locomotor system.…”