1,5-year course of quadriceps muscle strength following mild-to-critical Covid-19

ABSTRACT

Background: Muscle weakness is prevalent among post-Covid-19 patients, but longitudinal studies quantifying muscle strength following Covid-19 are lacking. Aim(s) To describe the course of quadriceps muscle strength over ~1,5 year following Covid-19. Method(s) A prospective analysis of 63 hospitalized (age 60+/-9y, 68% male) and 31 non-hospitalized (age 52+/-15y, 36% male) post-Covid-19 patients with persisting symptoms ('long covid') was performed. Isometric quadriceps maximal voluntary contraction (MVC) was evaluated using a computerized dynamometer at a knee angle of 60degree during 3 visits in hospitalized (89 [80-104], 215 [198-233], 434 [416-478] days after Covid-19) and non-hospitalized (138 [114-176], 282 [249-347], 540 [486-596] days after Covid-19) patients. MVC was expressed as percentage predicted and muscle weakness was defined as MVC <lower limits of normal. Result(s) Over the 3 visits, hospitalized patients had a MVC of 65+/-18, 70+/-17, and 68+/-16 %pred, and muscle weakness was present in 54, 49, 51% of cases, respectively. Similarly, non-hospitalized patients had a MVC of 70+/-16, 76+/-17, and 74+/-19 %pred, and a muscle weakness prevalence of 65, 52, and 52% was found. In both groups, MVC improved between visit 1 and 2 (p<0,05) whereas no change was observed between visit 2 and 3. The prevalence of muscle weakness in both groups did not change significantly. Conclusion(s) Quadriceps muscle strength modestly improves during the first 7-9 months following acute Covid-19 in both hospitalized and non-hospitalized 'long covid' patients. However, still half of the patients in both groups had long-term muscle weakness. Further investigation is needed into the aetiology of muscle weakness in post-Covid-19 patients.