This question on how often should someone run to maintain ability got me thinking how often one would need to strength train to maintain their current level of strength. The answer to this post about alternating emphasis would make me think that 2x a week is sufficient for maintenance, but the 1/3 volume for vo2 max preservation in running got me thinking what is truly the minimum volume &/or intensity that one would need to train for maintain their strength.
Strength can be maintained with as little as one-ninth original volume.
Bickel et al examined this with a 16 week training intervention, followed by a 32 week detraining/reduced volume maintenance protocol.1 As expected, specific strength deteriorated after cessation of training, but still remained above baseline after 32 weeks of detraining. In the one-third and one-ninth volume groups, we see further increases in strength beyond the initial intervention. Not only is maintenance possible with only one-ninth the original volume, this study observed further strength gains. The interesting thing is that these gains in strength seem to be independent of hypertrophy adaptations, which were found to be somewhat less resilient to reduced volume, especially in the older group.
It should be noted, of course, that this study is reporting group level averages, and there is typically a great deal of individual variation within strength and hypertrophy studies. So you will need to do some experimentation to figure out what works for you, and I would generally recommend staying on the safe side by getting closer to one-third volume, rather than one-ninth.
Greg Nuckols goes into much greater detail about preserving gains while detraining or reducing training volume in his article "A Guide To Detraining: What To Expect, How To Mitigate Losses, And How To Get Back To Full Strength".
1 Bickel CS, Cross JM, Bamman MM. Exercise dosing to retain resistance training adaptations in young and older adults. Med Sci Sports Exerc. 2011 Jul;43(7):1177-87. doi: 10.1249/MSS.0b013e318207c15d. PMID: 21131862.
Further reading, featuring similar findings:
Spiering BA, Mujika I, Sharp MA, Foulis SA. Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time. J Strength Cond Res. 2021 May 1;35(5):1449-1458. doi: 10.1519/JSC.0000000000003964. PMID: 33629972.
Trappe S, Williamson D, Godard M. Maintenance of whole muscle strength and size following resistance training in older men. J Gerontol A Biol Sci Med Sci. 2002 Apr;57(4):B138-43. doi: 10.1093/gerona/57.4.b138. PMID: 11909878.
Rønnestad BR, Nymark BS, Raastad T. Effects of in-season strength maintenance training frequency in professional soccer players. J Strength Cond Res. 2011 Oct;25(10):2653-60. doi: 10.1519/JSC.0b013e31822dcd96. PMID: 21873897.