Impact of sedentarism due to the COVID‐19 home confinement on neuromuscular, cardiovascular and metabolic health: Physiological and pathophysiological implications and recommendations for physical and nutritional countermeasures

Abstract

The COVID-19 pandemic is an unprecedented health crisis as entire populations have been asked to self-isolate and live in home-confinement for several weeks to months, which in itself represents a physiological challenge with significant health risks. This paper describes the impact of sedentarism on the human body at the level of the muscular, cardiovascular, metabolic, endocrine and nervous systems and is based on evidence from several models of inactivity, including bed rest, unilateral limb suspension, and step-reduction. Data form these studies show that muscle wasting occurs rapidly, being detectable within two days of inactivity. This loss of muscle mass is associated with fibre denervation, neuromuscular junction damage and upregulation of protein breakdown, but is mostly explained by the suppression of muscle protein synthesis. Inactivity also affects glucose homeostasis as just few days of step reduction or bed rest, reduce insulin sensitivity, principally in muscle. Additionally, aerobic capacity is impaired at all levels of the O 2 cascade, from the cardiovascular system, including peripheral circulation, to skeletal muscle oxidative function. Positive energy balance during physical inactivity is associated with fat deposition, associated with systemic inflammation and activation of antioxidant defences, exacerbating muscle loss. Importantly, these deleterious effects of inactivity can be diminished by routine exercise practice, but the exercise dose-response relationship is currently unknown. Nevertheless, low to mediumintensity high volume resistive exercise, easily implementable in home-settings, will have positive effects, particularly if combined with a 15-25% reduction in daily energy intake. This combined regimen seems ideal for preserving neuromuscular, metabolic and cardiovascular health.. Just few days of sedentary lifestyle are sufficient to induce muscle loss, neuromuscular junction damage and fibre denervation, insulin resistance, decreased aerobic capacity, fat deposition and low-grade systemic inflammation. . Regular low/medium intensity high volume exercise, together with a 15-25% reduction in caloric intake are recommended for preserving neuromuscular, cardiovascular, metabolic and endocrine health.2 M. Narici et al.

“I am terrified of something happening to me” The lived experience of people with obesity during the COVID‐19 pandemic

“…Overall, these barriers and the lack of accessibility to resources during the pandemic are having a profound impact on the nature of patient engagement in treatment. COVID‐19 associated sedentariness may have a negative impact on health, regardless of weight status 39 . Our findings reveal a negative impact of the pandemic on sustaining exercise due to temporospatial, musculoskeletal and psychosocial factors.…”

Sedentary Behaviors and Physical Activity of Italian Undergraduate Students during Lockdown at the Time of CoViD−19 Pandemic

“…Inactivity and sedentary behavior have numerous negative effects on human health at muscular, cardiovascular, metabolic and endocrine levels, also affecting psychological wellbeing [ 6 , 9 , 10 ]. These effects are mediated by mechanisms such as the development of muscle atrophy, the reduction of muscle insulin sensitivity and aerobic capacity and changes in body composition, which may occur even after limited periods of inactivity [ 4 , 5 ]. University students in particular are exposed to unhealthy sedentary and dietary habits also in the non-pandemic period, especially if living away from home [ 11 ].…”

The Effects of COVID-19 and Quarantine Measures on the Lifestyles and Mental Health of People Over 60 at Increased Risk of Dementia

“…Also a decrease in the amount of time spent being physically active might have negative consequence on cognition and mental health. In a recent literature review, Narici et al ( 19 ) described the impact of sedentariness potentially associated to COVID-19 on human body at the level of muscular, cardiovascular, metabolic, endocrine, and nervous systems and on the basis of several models of inactivity, including bed or couch rest, and reduced number of steps. A few days of sedentary life are enough to induce muscular loss, damage to neuromuscular junction and fibers' denervation (neuromuscular integrity is strictly binded to mitochondrial function), insulin resistance, reduction in aerobic capacity, fat deposition and low-grade systemic inflammation.…”