Attentional Focusing Instructions Influence Force Characteristics During Knee Extension Exercise

Attentional focusing instructions (either internally or externally focused) can have a significant influence on the muscular activity during exercise type movements (e.g., (Vance, et al., 2004; Marchant, et al., 2008). Specifically, externally focused instructions (direct attention towards the movements being carried out and the object through which force is being exerted) result in lower EMG values when compared to internally focused instructions (directing attention to the movements of the limb involved in the movement). Recently (Marchant, et al., in press), externally focused instructions resulted in increased force production during elbow flexions when compared to internally focused instructions. The present research further addresses the nature of these force production characteristics during instructed exercise movements. Methods 15 healthy participants completed 10 isokinetic knee extension repetitions on a Biodex System 3 dynamometer under two counterbalanced conditions: production of maximal force using verbal internally (focusing attention onto the movements of the leg) and externally (focusing attention onto exerting force through the leg pad) focused instructions. Measures were the integral of the torque-time curve (iT), force variability (fV – SD in iT) and a fatigue index (FI - % decline in iT). A 2 (Attentional Focus Type) X 8 (Repetition) Repeated Measures ANOVA analysed differences in iT. Paired samples t-tests were used to assess differences in fV and FI. Results iT was significantly (p < 0.05) greater when external focus was adopted (126.88, SE = 8.59 N m) compared to an internal focus (119.20, SE = 9.67 N m). An external focus was also associated with significantly (p < 0.05) greater fV (10.17 N m) compared to an internal focus (8.00 N m), but there were no differences in observed fatigue over the course of repetitions in either internal (88.72%) or external (85.55%) focus condition. Discussion/Conclusion Supporting recent previous research, an external focus of attention increased force production in an exercise task when compared to an internal focus. Attentional focus did not influence fatigue characteristics effects over the course of this exercise, but requires further research. These findings have significant implications for the instruction of exercise and rehabilitation exercises.