Purpose Adults with subjective cognitive decline (SCD), the self-reported concern of reduced cognitive function, are recommended to do physical activity for its brain health benefits. US adults aged ≥45 with SCD are less likely to meet the American College of Sports Medicine (ACSM) aerobic activity recommendations. Their engagement in muscle-strengthening activities is unknown. We aimed to identify if US adults aged ≥45 with SCD are less likely to do twice-weekly muscle-strengthening activities compared to those without SCD. Design Secondary analysis of the 2019 Behavioral Risk Factor Surveillance System (BRFSS) data. Sample 114 164 respondents, representing approximately 59 million US adults aged ≥45. Measures SCD was indicated if the respondent reported confusion or memory loss during the past 12 months (yes/no). Respondents reported the frequency of muscle-strengthening activities, which we categorized as meeting the ACSM’s recommendations (2+ times per week) or not (<2 times per week). Analysis Crude and adjusted logistic regression models controlling for variables associated with SCD and muscle-strengthening activities. The models used sample weights to represent US adults in the included 31 states and Washington D.C. Results US adults aged ≥45 with SCD were less likely to do twice-weekly muscle-strengthening activities than those without SCD (28.6% [SE: .8%] vs 33.5% [SE: .3%], adjusted OR, .9; 95% CI: .9-1.0). Conclusion Primary care providers should encourage middle-aged and older patients to engage in muscle-strengthening and aerobic activities.