■神经肌肉疲劳会导致肌肉力量短暂减少,并改变电机控制的机制。这些改变是否会增加前交叉韧带(ACL)损伤的风险仍存在争议。在这里,我们比较了在进行疲劳运动之前和之后单腿跳伞的生物力学,评估这项运动是否会导致生物力学改变,通常与ACL病变风险增加相关。疲劳协议的强度是根据每个参与者的有氧能力量身定制的,最大限度地减少由于个体间适应性差异而产生的潜在差异效应。
■24名健康男性志愿者进行单腿跳伞,在自行车测功机上进行单组疲劳试验之前和之后,直到精疲力竭(节奏:每分钟65-70转)。对于每个参与者,疲劳运动的强度设置为无氧阈值所达到的功率的110%,先前通过心肺运动测试确定。关节角度和力矩,比较了优势腿和非优势腿的疲劳运动前后的地面反作用力(GRF)。
■疲劳练习后,髋关节更伸展(着陆:Δ=-2.17°,p=0.005;推进力:Δ=-1.83°,p=0.032)和更多的被绑架(着陆:Δ=-0.72°,p=0.01;推进力:Δ=-1.12°,p=0.009)。同样,着陆时膝关节更加伸展(非优势腿:Δ=-2.67°,p<0.001;优势:Δ=-1.4°,p=0.023),更多的是在推进时被绑架(两条腿:Δ=-0.99°,p<0.001)和稳定(双腿:Δ=-1.71°,p<0.001),因此增加了膝关节外翻。疲劳还导致着陆时垂直GRF显著降低(Δ=-0.21N/kg,p=0.003),但不是在推进期间。疲劳并未显着影响关节力矩。
■臀部和膝盖伸展增加,以及我们在进行疲劳运动后观察到的膝关节外展增加,先前已被确定为ACL损伤的危险因素。因此,这些结果表明,在执行此处提出的参与者量身定制的疲劳协议后,ACL损伤的风险增加。然而,着陆时降低的垂直GRF和关节力矩的保留是有趣的,因为他们可能建议在疲劳状况下采取保护性策略,以便在未来的研究中进行评估。
UNASSIGNED: Neuromuscular fatigue causes a transient reduction of muscle force, and alters the mechanisms of motor control. Whether these alterations increase the risk of anterior cruciate ligament (ACL) injury is still debated. Here we compare the biomechanics of single-leg drop jumps before and after the execution of a fatiguing exercise, evaluating whether this exercise causes biomechanical alterations typically associated with an increased risk of ACL lesion. The intensity of the fatiguing protocol was tailored to the aerobic capacity of each participant, minimizing potential differential effects due to inter-individual variability in fitness.
UNASSIGNED: Twenty-four healthy male volunteers performed single leg drop jumps, before and after a single-set fatiguing session on a cycle ergometer until exhaustion (cadence: 65-70 revolutions per minute). For each participant, the intensity of the fatiguing exercise was set to 110% of the power achieved at their anaerobic threshold, previously identified by means of a cardiopulmonary exercise test. Joint angles and moments, as well as ground reaction forces (GRF) before and after the fatiguing exercise were compared for both the dominant and the non-dominant leg.
UNASSIGNED: Following the fatiguing exercise, the hip joint was more extended (
landing: Δ=-2.17°, p = 0.005; propulsion: Δ=-1.83°, p = 0.032) and more abducted (
landing: Δ=-0.72°, p = 0.01; propulsion: Δ=-1.12°, p = 0.009). Similarly, the knee joint was more extended at
landing (non-dominant leg: Δ=-2.67°, p < 0.001; dominant: Δ=-1.4°, p = 0.023), and more abducted at propulsion (both legs: Δ=-0.99°, p < 0.001) and stabilization (both legs: Δ=-1.71°, p < 0.001) hence increasing knee valgus. Fatigue also caused a significant reduction of vertical GRF upon
landing (Δ=-0.21 N/kg, p = 0.003), but not during propulsion. Fatigue did not affect joint moments significantly.
UNASSIGNED: The increased hip and knee extension, as well as the increased knee abduction we observed after the execution of the fatiguing exercise have been previously identified as risk factors for ACL injury. These results therefore suggest an increased risk of ACL injury after the execution of the participant-tailored fatiguing protocol proposed here. However, the reduced vertical GRF upon
landing and the preservation of joint moments are intriguing, as they may suggest the adoption of protective strategies in the fatigued condition to be evaluated in future studied.