Effects of a Low Volume Injury Prevention Program on the Hamstring Torque Angle Relationship

Abstract

The effects of a 4-week lower body injury prevention program on knee muscle torque-angle relationship were examined in soccer players. Twenty men were randomly allocated to either a control (n = 10) or training group (n = 10). The training group underwent three training sessions per week, comprising 3 sets of 8 repetitions of one open-chain exercise (Nordic curl) and two closed-chain exercises-forward lunges on a Bosu balance trainer and eccentric single leg dead lifts. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100° pre- and post-intervention. Significant improvements were observed only at 80° (p = .001; d = .94) along with a nonsignificant trend at 35° (p = .081; d = .43). As these modifications might protect athletes against muscle and joint injuries, the use of both stable-open and unstable-closed kinetic chain exercises emphasizing eccentric hamstring and knee stabilization actions should be integrated into injury prevention programs in team sports athletes.

The effectiveness of different exercises protocols to prevent the incidence of hamstring injury in athletes

“…Different eccentric exercises using a fly wheel eccentric leg curl 19 , Nordic Curl alone 8,20 combined with other strengthening 21 or stretching exercises 21,22 have been successfully applied for reducing the incidence of hamstring injuries, enhancing hamstring eccentric strength 23 or shifting the optimal peak torque in non-previous injured a thletes [24][25][26] . However, the loading patterns and the appropriate training protocols continue to be determined.…”

“…In addition, to the active lengthening observed during sprints or kicking, the hamstring acts as knee stabilisers counteracting and balancing the actions of the quadriceps during sportspecific activities, such as landing, deceleration or change of direction. Therefore, specific drills involving, repeated sprints, jumps, hops combined with unstable coreexercises, namely one-leg squat or lunges unstable surfaces have been proposed as effective methods for preventing hamstring injuries 24,27,28 . Verral et al 28 reported a significant reduction of hamstring injuries in Australian football players after a four-year high-intensity intervaltraining programme combined with passive isometric hamstring stretching.…”

“…Conversely, Daneshjoo et al 27 observed no effect of two typically recommended specific injury prevention programmes (FIFA 11 + and Harmo Knee) to enhance hamstring strength in professional football players. More recently, Naclerio et al 24 reported that four weeks (12 sessions) of an injury prevention programme comprising three sets of eight repetitions of the Nordic curl, forward lunges on a Bosu ® , balance trainer and eccentric single-leg dead lifts was effective in improving the maximal isometric force at both closed (80°) and open (35°) knee angles. Figure 3, depicts the torque-angle profiles determined before (for all participants n = 20) and after the training programme differentiating the training (n = 10) and control group (n = 10).…”

“…When performing lunges, a more quasiisometric action of the hamstring will be required and therefore, a predominant strengthening at closer knee angles would be elicited. The single-leg dead lifts involves both an active stretch and a knee stabiliser co-contraction actions of the hamstrings that in turn will be stimulating an strength enhancement of the hamstring at both the closer and the open knee angles positions 24 .…”

“…Key point for designing a hamstring injury prevention programme • The positive effects of a low-volume injury prevention programme could be obtained over a four-week period, with only two sessions per week ivolving three sets of six to eight repetitions of three open and closed kinetic chain exercises 24,25 . • The selected exercises should involve eccentric and quasi-isometric hamstring muscle actions 24 .…”