Standing curls: trained lifters differ in trunk timing

Standing curls involve the trunk as well as the elbow flexors. A Neuroscience Letters study published on October 29, 2026 found a narrower timing gap between the onset of erector spinae and biceps activity in trained men during a visual-cued task. The trained group comprised 15 men with at least three years of strength training; the comparison group comprised 15 untrained men. The outcome was when activation began, rather than how large the muscles were.

How were the curl conditions compared?

Participants stood and performed rapid bilateral curls with 35% of their individual one-repetition maximum. Researchers recorded EMG from the right biceps brachii and erector spinae while changing the signal that initiated the movement. This was a laboratory reaction task, not a multiweek comparison of bodybuilding programmes. The load therefore describes the test; it does not establish an optimal training intensity.

Does earlier activation mean more muscle growth?

Muscle growth was not measured. The relative shortening of biceps onset produced by the startling signal was smaller in trained men, whereas the erector spinae response did not show that group difference. The authors interpreted the pattern as consistent with muscle-specific differences in reticulospinal contributions. That is an indirect interpretation of the response, not a direct recording of a neural pathway or evidence that trained lifters are superior on every reaction measure.

What should go into a workout log?

Because the groups were compared at one point in time, training cannot be isolated as the cause of their coordination difference. A useful editorial application is to keep the conditions behind a curl record comparable. The following logging suggestions are not a technique intervention validated by this experiment; they help distinguish a change in performance from a change in how a repetition was executed.

1. Distinguish standing curls from seated curl conditions.
2. Record load and repetitions, and note whether body swing was used.
3. When load rises, check whether trunk movement also changed.

In fairlift, keep curl loads and repetitions as accessory-work records rather than treating them as an increase in the Big 3 score. The Muscle Index calculator uses squat, bench press and deadlift one-repetition maximums. For a separate question about the magnitude of the EMG signal, read the comparison of biceps activation across curl variations. Signal magnitude and activation timing should not be read as interchangeable outcomes.