The influence of 'Slacklining' on quadriceps rehabilitation, activation and intensity

To determine and compare the level of quadriceps activation for knee injured participants during kinetic open-chain, closed-chain and composite-chain (Slackline) clinical exercises. Quadriceps activation is a critical component of lower limb movement and subsequently, rehabilitation. However, selective activation can be difficult due to pain, loss of function and impaired neuro-motor activation.

Repeated measures (within-subjects) ANOVA.

Consecutive physiotherapy outpatients (n=49, 41.8±16.8 years, range 13-72 years, 57% female) with an acute (<2 weeks) knee injury were recruited. Participants were assessed for quadriceps activation using skin mounted electromyography during five separate clinical quadriceps activation exercises: two open-chain, inner range quads and straight leg raise; two closed-chain, step down and step up; and a composite-chain, slacklining step-up. Outcome measures were: median score on electromyography as measured in microvolts (μV); and perceived exertion on an 11-point numerical rating scale.

Median scores of the open- and closed-chain exercises showed no statistical difference, while composite-chain Slackline exercise showed significantly (p<0.0001) higher quadriceps activation (F(2.52, 121.00)=21.53, p<0.0001) at significantly lower exertion (F(1.62, 77.70)=26.88, p<0.0001).

The use of Slackline rehabilitation training can provide significant increases in activation and recruitment of the quadriceps for composite-chain exercises in the clinical setting. This activation occurs spontaneously at significantly lower levels of perceived exertion. This spontaneous quadriceps activation in a selective and simple manner is a valuable adjunct exercise for lower limb rehabilitation programmes. This is of particular relevance for the outpatient setting and circumstances where the quadriceps is inhibited and activation is required.