Is Lactic Acid Related to Delayed-Onset Muscle Soreness?

Area of Science:

• Exercise Physiology
• Sports Medicine
• Biochemistry

Background:

• Delayed-onset muscle soreness (DOMS) is a common post-exercise phenomenon.
• The role of lactic acid in DOMS has been a long-standing hypothesis.
• Understanding DOMS triggers is crucial for athlete recovery and performance.

Purpose of the Study:

• To investigate the relationship between blood lactic acid concentration and DOMS following running exercise.
• To differentiate the effects of level versus downhill running on lactic acid production and subsequent muscle soreness.

Main Methods:

• Participants ran on a treadmill for 45 minutes, once on a level surface and once on a -10% incline.
• Blood lactic acid levels were measured before, during, and up to 72 hours post-exercise.
• Subjective muscle soreness was also recorded at regular intervals over the 72-hour period.

Main Results:

• Lactic acid significantly increased during level running, yet no significant DOMS was reported.
• Downhill running did not elevate lactic acid levels, but participants experienced significant DOMS.
• A clear dissociation between elevated blood lactic acid and the onset of muscle soreness was observed.

Conclusions:

• The study concludes that lactic acid accumulation is not the cause of exercise-induced DOMS.
• These findings challenge the traditional hypothesis linking lactic acid to muscle soreness.
• Further research should explore other biochemical or mechanical factors contributing to DOMS.