When rats do low-frequency weightlifting, their blood doesn't show signs of muscle soreness or energy stress, meaning this kind of exercise doesn't hurt or tire their muscles.

A randomized controlled trial in rats where subjects are assigned to either low-frequency resistance training or a no-exercise control group, with serum creatine kinase and lactate measured before and after a standardized training period (e.g., 4–8 weeks, 2 sessions/week), using blinded lab analysis to ensure outcome reliability.

A prospective cohort study tracking multiple groups of rats exposed to different resistance training frequencies (including low-frequency) over time, measuring serum creatine kinase and lactate at regular intervals to compare changes across groups without randomization.

A cross-sectional comparison of rats currently undergoing low-frequency resistance training versus sedentary rats, measuring serum creatine kinase and lactate at a single time point to assess differences.

A case-control study comparing rats identified as having 'no muscle damage' (normal creatine kinase and lactate) with those showing elevated levels, retrospectively assessing whether they performed low-frequency resistance training.

An in vitro study using rat muscle cell cultures exposed to simulated low-frequency mechanical stress to observe lactate and creatine kinase release patterns.