The immediate effects of open kinetic chain knee extensor exercise at different loads on knee anterior laxity in the uninjured

BackgroundThere is evidence that anterior laxity may be affected by knee extensor open kinetic chain (OKC) exercise with responses being load-dependent. The aim of this study is to evaluate the immediate and short-term changes in passive knee anterior laxity following a single session of OKC knee extensor exercise.MethodsThirty two participants were randomly allocated to perform either high load (20 sets of 2 repetitions) or low load (2 sets of 20 repetitions) knee extensor OKC exercise with knee anterior laxity assessed before exercise, immediately after exercise and 45 and 90 min after exercise with a KT-2000 arthrometer using a 133 N force.ResultsA significant effect of time was observed on knee laxity (p < 0.001). However, a significant interaction of time and group was not found (p = 0.54) and so the results presented here are for the combined (low and high load) group mean ± standard deviation knee anterior laxity (mm) in the exercised leg: 7.2 ± 2.2 (baseline), 8.2 ± 2.3 (immediate post exercise, 14% change from baseline), 8.1 ± 2.3 (45 min post exercise, 12% change from baseline), and 7.7 ± 2.2/0.29 (6.9) (90 min post exercise, 7% change from baseline).ConclusionOKC knee extensor exercise at high loads and low loads causes an immediate increase in knee laxity that begins to decrease within 90 min.