ABSTRACT
Objective To compare the knee function recovery at different times of returning to sport after anterior cruciate ligament reconstruction(ACLR) among elite athletes using knee isokinetic muscle strength test and various hop test.Methods Forty-one elite athletes(14 males,27 females,mean age 22.6 ± 4.1 years) undergoing ACLR between January 2013 and September 2014 were chosen from the database of the National Institute of Sports Medicine and Shanghai Huashan Hospital.Rehabilitation was performed using the same protocol by professional physiotherapists and trainers,who recorded the time of returning to sport of each athlete.One week prior to the scheduled return,bilateral knee isokinetic muscle strength test(test value:peak torque;angle velocity:60°/s,180°/s;motion:flexion,extension) and four hop tests(single hop for distance,side-to-side hop,up-down hop and 8 hop) were applied with the limb symmetry index(LSI) calculated.The athletes were then grouped by their returntime referring to surgery into the premature group(6～8 months),timely return group(9～12 months) and delayed group(over 12 months).The tests results were recorded and compared among the three groups.Results Fourteen athletes were selected into the premature group,with 19 in the timely group and 8 in the delayed group.The average LSI of 60°/s flexion peak torque of the premature group (87.4％ ± 7.5％) was significantly lower than the timely group(95.8％ ± 6.6％) and the delayed group(96.0％ ± 2.4％) (P＜0.01).Significant differences were observed between the premature group and delayed group regarding the 60° extension peak torque(85.8％ ± 9.4％ and 94.8％ ± 4.8％,P＜0.05),180°/s flexion peak torque(90.7％ ± 8.7％ and 101.4％ ± 6.8％,P＜0.05),and 180°/s extension peak torque (90.6％ ± 5.2％ and 97.8％ ± 5.6％,P＜0.05).The average LSL of the premature group at single hop for distance,side-to-side hop and up-down hop(93.A％ ± 8.5％,84.7％ ± 7.3％ and 112.5％ ± 5.7％) was significantly lower than that of the timely group(95.7％ ± 6.0％,104.2％ ± 4.3％ and 105.3％ ± 7.9％) and the delayed group regarding(98.1％ ± 1.9％,104.7％ ± 4.0％ and 106.3％ ± 7.4％) (P＜0.01 for all).The relative peak torque of 60°/s extension of the premature group(2.48 ± 0.58 Nm/kg) was significantly lower than the delayed group(3.21 ± 0.51 Nm/kg) (P＜0.01).Conclusions For elite athletes,returning to sport within 9 months after ACLR results in insufficient restoration of the knee function.Delayed return to sport doesn't improve the outcomes of hop tests,but can enhance the maximum extension torque peak,which needs further study.
ABSTRACT
The purpose of this study was to clarify physical characteristics related to low back pain (LBP) in collegiate track and field athletes. We particularly focused on the nature of the track and field. The subjects were 21 male collegiate track and field athletes including only sprinters, hurdlers, long jumpers and triple jumpers. The examined parameters were physical characteristics, isokinetic flexor and extensor strength in the knee and trunk regions. The evaluation of LBP was estimated by a questionnaire test and orthopedic surgeons' diagnosis. According to these evaluations, we divided all track and field athletes into two groups ; LBP group (n＝11, 52.4%) and no LBP group (n＝10, 47.6%). As a result, a take-off leg of knee flexor/extensor strength ratio in the LBP group was significantly lower than that in the no LBP group (<i>P</i>＜0.05). The LBP group showed a significant difference between a take-off leg and a lead leg in knee flexor strength compared with the no LBP group (<i>P</i>＜0.05). The LBP group has been short engaged in the track and field than the no LBP group (<i>P</i>＜0.05). In the trunk flexor and extensor strength, there was no significant difference between the LBP and the no LBP group in this study. These results suggest that the imbalanced knee muscle strength may be one of some factors related to chronic low back pain in collegiate track and field athletes.