Helen Lavelle and Rob Baker
Introduction: Rib stress fractures result from a nutcracker action on the ribs as the load on the blade is counteracted by the posterior scapular muscles. One of many factors is the proportion of force production from the arms in relation to the legs. If the arms give more the load on the ribs is greater.
Methods: This study sought to find a simple rowing ergometer test which is functional but accurately reflects the ratio of force contribution between the arms and the rest of the body. The new test was used to establish normative data for the protocol and a re-test study was conducted to investigate the reliability of the test protocol.
Results: The results were gender specific with men having a higher arm contribution percentage than women. Both groups were tested at two ratings 18 strokes/min and 26 strokes/min (s/m). Both groups had a lower arm contribution at the faster rating. At 18 strokes per min, the women averaged 21.85% of their power from their arms compared with 27.8% in the men. At 26 s/m the women averaged 18.35% and the men 23.2%. However, these figures are contrasted with an average from the cohort of normal (no history of rib issues) elite rowers who produced only 10% of their power from their arms at 18 s/m and 7.47% at the higher rating of 26 s/m. Test re-test validity showed the test is reliable to 1.8%.
Conclusion: This test could be used as a training aid to modify technique and a screen to look for subjects at risk. The recommendation of the co-author and experienced coach, Rob Baker, is that using results from this test at 18 s/m; the arm contribution of non-elite rowers should aim not to exceed 20% in women and 25% in men. Elite rowers should aim for 10%.
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