RESUMEN
OBJECTIVE: To assess the hypothesis that subjects exposed to intermittent hyperbaric oxygen treatments would recover from signs and symptoms indicative of delayed-onset muscle soreness faster than subjects exposed to normoxic air. DESIGN: Randomized, double-blinded study with a 4-day treatment protocol. SETTING: University-based sports medicine clinic. PARTICIPANTS: Sixteen sedentary female university students. INTERVENTIONS: All subjects performed 300 maximal voluntary eccentric contractions (30 sets of 10 repetitions per minute) of their nondominant leg (110 to 35 degrees of knee flexion) at a slow speed (30 degrees per second) on a dynamometer to elicit muscle damage and injury. Hyperbaric oxygen treatments consisted of 100% oxygen for 60 minutes at 2.0 atmospheres absolute (ATA), while the control group received 21% oxygen at 1.2 ATA for the same amount of time. Both groups received treatment immediately after the induction of delayed-onset muscle soreness and each day thereafter for a period of 4 days (day 1 postexercise through day 4 postexercise). MAIN OUTCOME MEASURES: Dependent variables (perceived muscle soreness, isokinetic strength, quadriceps circumference, creatine kinase, and malondialdehyde) were assessed at baseline (preexercise, day 0), 4 hours postexercise (day 1), 24 hours postexercise (day 2), 48 hours postexercise (day 3), and 72 hours postexercise (day 4). Magnetic resonance images (T2 relaxation time/short tip inversion recovery) were assessed at baseline (day 0), 24 hours postexercise (day 3), and 72 hours postexercise (day 5). RESULTS: Repeated-measures analysis of variance was performed on all of the dependent variables to assess differences between treatment and control groups. Analyses revealed no significant differences between groups for treatment effects for any of the dependent variables (pain, strength, quadriceps circumference, creatine kinase, malondialdehyde, or magnetic resonance images). CONCLUSIONS: The findings of this study suggest that hyperbaric oxygen therapy is not effective in the treatment of exercise-induced muscle injury as indicated by the markers evaluated.