I’ve long recommended working out your muscles eccentrically (doing negative work) in rehabbing from a muscle or tendon injury.  Briefly, eccentric contraction means focusing on lowering the weight slowly instead of on lifting it. (Check out “muscle injury recovery and eccentric workouts” if you need a review.)

But eccentric loading of a muscle does create more stress on the tendon.  Some experts worry that, if done injudiciously, eccentric exercise can lead to injury.

Now researchers have studied the risk for muscle injury with eccentric contractions compared to concentric contractions.  Instead of waiting for athletes to injure their muscles,  the scientists tested the subjects’ urine for the metabolic breakdown products that are a sign of muscle damage.

If subjects tried a single exercise session at which they maxed out their eccentric load – going for the heaviest weight stack they could manage right from the get-go – there was an increased level of muscle breakdown, potentially indicating a higher risk for injury.

But if the subjects built up their exercise capacity, beginning with 70 – 80% of their maximal load and progressing upward from there, the strength gains from eccentric loading outstripped those from concentric loading, with no increased risk of muscle injury.

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Tendonitis symptoms and eccentric workouts

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