Pick me, Pick me! Rationale for investigating persistent inward currents (PICs) and associated exercise effects in the ageing neuromuscular system

Estimates of persistent inward currents are reduced in upper limb motor units of older adults

“…In the words of Power and colleagues (2016), 'If you don't use it, you'll likely lose it' . Whether this holds true for PICs is unclear at the moment, although Latella (2021) recently made a compelling argument for studying the efficacy of strength training to mitigate the effects of ageing on MU firing behaviour. Indeed, the work of Power and colleagues (2010) suggests that estimates of MU numbers are greater in masters runners compared to their sedentary counterparts, though contrasting evidence has since shown that masters runners may not be spared from MU remodelling (Piasecki et al 2016).…”

“…Furthermore, recent work has called for the investigation of PIC estimates in the ageing neuromuscular system (Latella, 2021). The function of two primary monoaminergic nuclei in the brainstem, the raphe nuclei and locus coeruleus, have been shown to deteriorate with age (Shibata et al 2006;Pagano et al 2017).…”

Estimates of persistent inward currents are reduced in upper limb motor units of older adults

“…In the words of Power and colleagues (Power et al, 2016) -"If you don't use it, you'll likely lose it." Whether this holds true for PICs is unclear at the moment, although Latella (Latella, 2021) recently made a compelling argument for studying the efficacy of strength training to mitigate the effects of aging on MU firing behaviour. Indeed, the work of Power and colleagues (Power et al, 2010) suggests that estimates of MU numbers are greater in masters runners compared to their sedentary counterparts.…”

“…monoamine receptor or ion channel function), and inhibition may alter MU firing patterns, as well as estimates of PICs, with age (Johnson et al, 2017). Furthermore, recent work has called for the investigation of PIC estimates in the aging neuromuscular system (Latella, 2021). The function of two primary monoaminergic nuclei in the brainstem, the raphe nuclei and locus coeruleus, have been shown to deteriorate with age (Shibata et al, 2006;Pagano et al, 2017).…”

Intrinsic motoneuron excitability is reduced in soleus and tibialis anterior of older adults

“…With respect to the monoaminergic system, research using both human and animal models suggests that aging is associated with reduced noradrenaline and serotonin secretions and thus input onto the motoneurons [ 19 – 23 ], which might theoretically underpin PIC amplitude reduction with aging. These findings indicate the possibility that PIC amplitude might be reduced in older adults; however, this hypothesis remains to be tested [ 24 ].…”