Are you returning after a workout hiatus? Be patient and also add strength training!
A longer period of inactivity will cause rapid loss in muscle mass. According to a Danish study (Vigelso et al., 2015), during a 2-week immobilization, a group of young men aged —23 years lost up to a third of their leg strength, which was equivalent to aging 40 or 50 years(!). An older group of men aged —68 years only lost a fourth of their strength.
How do you regain your strength and how long will it take? ”It’ll take you three times the amount of time you were inactive to regain the muscle mass that you’ve lost,” according to Martin Gram in the paper.
Source: Vigelso et al., ”Six weeks’ aerobic retraining after two weeks’ immobilization restores leg lean mass and aerobic capacity but does not fully rehabilitate leg strength in young and older men”, in Journal of Rehabilitation Medicine (2015; doi: 10.2340/16501977–1961), URL: http://www.medicaljournals.se/jrm/content/?doi=10.2340/16501977-1961