Physical inactivity induced neuromuscular impairment: comparison of younger and older adults

ARIS Code: J5-4593

Project duration: 1. 10. 2022–30. 9. 2025

Project leader: Boštjan Šimunić, PhD

Participating institute at ZRS Koper: Institute for Kinesiology Research

Physical inactivity (PI) is independent and already a 2nd mortality risk factor, causing >5 million deaths per year. It can be considered a pandemic because it reduces exercise tolerance and dramatically increases the risk of disease. The main phenomena occur at the level of muscle (loss of mass and strength), nervous system (impaired central and peripheral motor control), and metabolism (impaired oxidative metabolism and insulin resistance). Most studies focused only on muscle, on young people and few also on older people. Few studies addressed the interactions between muscles and neural control through sensorimotor loops and neuromuscular junctions (NMJ) that lead to exercise intolerance and whole-body metabolic impairments. PI affects all age groups, and little is known about the effects of PI on function in middle-aged adults (55-65). In addition, the recent outbreak of COVID -19 has triggered PI in millions of people of all ages worldwide and highlighted its deleterious consequences.

Project activities will focus on neuromuscular and metabolic deterioration during PI and recovery thereafter. The effects of PI will be studied using highly controlled bed rest (BR), which is considered the gold standard for studying PI, in 10 younger (18-30 years) and 10 older (55-65 years) male adults for 21 and 10 days, respectively. All participants will undergo 21 days of retraining. Because short-term (7-15 days) offloading is common in both the young and elderly, in bedridden patients after injury or surgery, and in critically ill, investigating the possible determinants of disproportionate reductions in muscle function compared with reductions in muscle size and structure is of great importance.

Although disuse is a major project goal, we will equally important study recovery part too. We will address 3 objectives using 10 interrelated tasks in young and middle-aged adults in PI models of bed rest (BR).