Time course of changes in bilateral arm power of swimmers during recovery from injury using a swim bench.

OBJECTIVES There has been little research on the time course of recovery from injury in athletes. This is especially the case for recovery in arm power in injured swimmers. The purpose of this study was to compare the power output of the injured and non-injured arms of swimmers during recovery from injury by use of a maximal exercise test on a computer interfaced isokinetic swim bench. METHODS Thirteen swimmers (five men and eight women; age 18.8 (3.2) years; stature 1.76 (0.05) m; body mass 61.7 (5.9) kg; mean (SD)) gave written informed consent and were recruited to this study throughout a three year period. All subjects had experienced non-aquatic soft tissue injury to their dominant-side shoulder or upper arm in the three months before participation, but had been allowed to return to swimming training. All of the subjects had injured their dominant arm and the mean time for absence from training was 3.7 (1.1) weeks. At return to training and at four, eight, and twelve weeks thereafter, subjects performed two all-out 30 second tests on the swim bench by simulating the swimming arm action. From these tests, peak power output (PPO), mean power output (MPO), and power decay (PD) for each arm during the 30 seconds of exercise could be determined by averaging the two tests. The differences between return to training and the four, eight, and twelve week periods were analysed using repeated measures analysis of variance with Tukey b post hoc test. RESULTS The repeated testing showed 95% confidence intervals of +/- 11.4 W for PPO, +/- 9.5 W for MPO and +/- 0.5 for PD. When the swimmers returned to training the results showed that PPO was 179 (21.9) v 111 (18.1) W (P = 0.02), MPO was 122 (9.8) v 101 (8.8) W (P = 0.01), and PD was 2.5 (0.6) v 5.2 (1.9) (P = 0.001) for non-injured and injured arms respectively (all values mean (SEM)). There were similar differences at four weeks which disappeared after eight weeks, except for that of PPO which was still evident (187.3 (21.9) v 156.8 (18.1) W; P = 0.01). At 12 weeks there were no differences between the non-injured and injured arm on any of the indices of arm power (P > 0.05). CONCLUSIONS These results suggest that, using the swim bench power test, differences in bilateral arm power output after injury persist for at least eight weeks after return to swimming training. These findings support the need for prolonged rehabilitation after such injury. This would best include physiotherapy and a training programme within which special consideration is given to the recuperation process.