When athletes first get involved with resistance training, they get sore, really sore. However, they progressively adapt to the training stimulus and eventually experience less soreness. This is largely due to the repeated bout effect. The repeated bout effect simply states that after performing an exercise once, there is a protective effect against muscle damage in subsequent bouts of similar exercise. This may explain why we get less sore with greater familiarity of an exercise stimulus.
The repeated bout effect is important to consider when designing in-season resistance training programs for your athletes. During this time, we want to maximize our return in the gym by maintaining or increasing strength and power. However, we also wish to accomplish this task without the burden of excess delayed onset muscle soreness. Too much soreness can interfere with practice quality and even worse, competition performance.
A recent study in the Journal of Strength and Conditioning Research tested whether the repeated bout effect worked for different, but similar exercises. In other words, will the protective effects that come from doing incline biceps curls also protect against damage caused by preacher curls; a similar but slightly different exercise. To answer this, twenty untrained males were divided into two groups. One group performed two identical workouts of incline biceps curls separated by 7 days. The other group performed the first workout with incline biceps curls and the second workout with preacher curls. Maximal torque production, range of motion, muscle soreness and creatine kinase (a marker of muscle damage) were measured before, immediately after and at 24, 48, 72 and 96 hours following each workout. No differences were found between groups for any of the measured markers.
The results of this study suggest that the repeated bout effect protects against muscle damage from similar exercise movements. In a practical sense, this is useful for varying exercise selection with athletes when we want to limit muscle damage and soreness, like during in-season training. Too much variation in exercise selection is likely to cause more soreness and muscle damage due to the novelty factor. For example, having athletes do weighted forward lunges when they have only been doing bilateral squats will likely create a great deal of soreness and therefore may not be ideal near competition. Therefore we should familiarize our athletes with exercises that we wish to perform in-season during preparatory phases to allow the repeated bout effect to take place.
Zourdos, MC., et al. Repeated bout effect in muscle-specific exercise variations. Journal of Strength and Conditioning Research, In press.