Effects of bilateral or unilateral lower body resistance exercises on markers of skeletal muscle damage.
Level 3 - non-randomized controlled study
Within-subject comparative study; randomization of condition order is not specified in the abstract.
PubMed 30709578 · doi:10.1016/j.bj.2018.10.003
What was done
Participants performed both bilateral and unilateral lower body resistance exercise sessions. One-repetition maximum (1RM) strength was estimated using the Brzycki Formula for each limb and movement. Blood samples were drawn before exercise, immediately after exercise, and 30 minutes post-exercise to measure creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Data were analyzed with a two-way repeated measures ANOVA.
What was found
No numerical values, baseline measurements, effect sizes, or variances were reported in the abstract. A statistically significant change across time points was observed for CK, AST, and ALT (p < 0.05). A statistically significant difference between exercise types was observed for LDH (p < 0.05), leading authors to conclude that unilateral exercise resulted in greater skeletal muscle damage.
Why it matters
Understanding the physiological recovery demands of unilateral versus bilateral movements can assist practitioners in programming exercise selection and training frequency.
Limits
The abstract omits the sample size, participant characteristics (age, sex, training experience), exercise modalities, and load parameters. It is not stated whether the order of exercise sessions was randomized. Measuring muscle damage markers only up to 30 minutes post-exercise is a major limitation, as enzymatic markers such as CK typically peak 24–72 hours after exercise.
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