Does more lean mass mean more strength?
Those are different outcomes. A 2017 systematic review of placebo-controlled trials in healthy young adults found body-composition changes without improved muscle strength over weeks to months. Its findings do not establish HGH as a routine strength-building treatment.
Promotional claims and approved uses
The FDA states that HGH is not approved for bodybuilding or anti-aging. Being older, training intensely or wanting more muscle does not itself establish a growth hormone deficiency.
If you are concerned about loss of strength
Discuss the change and possible causes with a licensed clinician. See the adult deficiency overview for a separate discussion of diagnosis. This article provides no HGH cycle, dose or performance-enhancement plan.