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This study aimed to describe changes in forelimb grip strength and ex vivo muscle force production in adult (Ad) and aged (Ag, 75% lifespan) male (M) and female (F) F344/BN hybrid rats. We hypothesized that differences in M vs. F would be explained by muscle mass, but that age differences would persist after normalizing to mass in fast, but not slow muscles. Forelimb grip was expressed in absolute terms (Grip) and relative to body mass (NGrip). Ex vivo forces of the extensor digitorum longus (EDL) and Soleus (Sol) were assessed at 3 stimulation frequencies and 2 pulse durations, and expressed as absolute muscle force (AMF) and muscle quality (MQ; force/anatomical cross‐sectional area). We also assessed sarcoplasmic reticulum (SR) Ca2+ release and reuptake from homogenates of both muscles. Body mass was higher in Ag vs. Ad and M vs. F (both p < 0.001), while EDL and Sol mass were smaller in F …