Acute Alterations of Scapular Upward Rotation following a Functional Fatiguing Protocol in Male Tennis Players
Context: Alterations in scapular kinematics, specifically upward rotation, are associated with a variety of chronic shoulder conditions. Fatigue may exacerbate the mechanisms potentially resulting in microtrauma and impingement syndrome. Objective: To identify acute alterations of scapular upward rotation following a functional fatigue protocol. Design: Prospective longitudinal. Setting: Biomechanics research laboratory. Patients or Other Participants: Twenty healthy, male competitive tennis players with no history of shoulder injury participated in this study: 10 experimental subjects(19.4 ± 1.07 yrs., 180.09 + 8.92 cm 72 + 11.56 kg) and 10 control subjects (19.6 ± 1.17 yrs., 181.1 + 6.56 cm 81.56 + 13.51 kg). Interventions: Scapular upward rotation was measured three times per session on the dominant arm while at rest, 60˚, 90˚ and 120˚ of humeral elevation in the scapular plane. Participants in the experimental group performed a tennis serving protocol and maintained at least 90% maximal exertion of the tennis serve. Fatigue was defined as reaching a rating of 15 using Borg’s rate of perceived exertion scale as well as 70% HR max. Upward rotation measurements were taken before and immediately following the fatigue protocol, and 24, 48, and 72 hours post exercise. Control participants were tested at the same time intervals without the fatiguing protocol. Main Outcome Measures: Four 2 x 5 (group x session) repeated measures ANOVA’s were performed followed by simple contrasts as appropriate. Results: Significant group by time interaction for scapular upward rotation was found at all testing positions (rest, 60˚, 90˚ and 120˚). Contrasts revealed differences between the experimental group’s pre fatigue and post fatigue values at all testing positions (pre fatigue rest: 1.48 + 2.66 post fatigue rest: -.68+ 2.66 p<.001; pre fatigue 60˚: 7.87+ 4.46 post fatigue 60˚: 5.67+ 4.72 p=.010; pre fatigue 90˚: 22.51+ 5.40 post fatigue 90˚: 19.29+ 5.16 p<.001; pre fatigue 120˚: 37.34+ 6.91 post fatigue 120˚: 33.35+ 6.49 p<.001; as well as at 60˚ pre fatigue and day four measurements(pre fatigue 60˚: 7.87+ 4.46 day 4 60˚: 7.67+ 4.55 p=.031) Conclusions: Fatigue appears to affect, specifically impairs, scapular upward rotation in male tennis players but returns to baseline values within twenty-four hours. Further research should identify when it returns to baseline to provide guidance for rest intervals for healthy male tennis players as well as if these changes are similar in a pathologic group of players.
ETD, Tennis, Scapula Kinematics, Upward rotation, Fatigue, Kinesiology
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