Does internal mental imagery help maintain muscle strength and force steadiness during immobilization?

Research has shown that immobilization such as that which occurs during treatment to an injury can results in significant muscle strength and force steadiness loss within the first week (Lundbye-Jensen & Nielsen, 2008; Newsom, Knight, & Balnave, 2003). Research has examined the efficacy of imagery in minimizing strength-loss during a period of immobilization (Newsom, Knight, & Balnave, 2003; Stenekes, Geertzen, Nicolai, De Jong, & Mulder, 2009). While promising, limitations remain with regards to type of imagery used and structures immobilized. This study assessed the effectiveness of using internal kinesthetic mental imagery to maintain thenar muscle group strength during immobilization of the thumb. Participants' thenar muscle group strength was measured pre- and post-immobilization period in adduction, abduction, opposition and flexion. Force steadiness was also evaluated pre- and post-immobilization at 5%, 25% and 50% of maximum thumb flexion force. All participants were immobilized for seven days on their non-dominant hand in a thumb spica cast. During the immobilization period, both the control and experimental groups were instructed to limit the use of their non-dominant hand. The experimental group completed a daily 8-minute imagery script. Results of separate repeated measure 2 (group) x2 (pre/post) ANOVAs failed to support the effect of imagery to maintain muscle strength or force steadiness following 7-days of immobilization. Future research should add a familiarization session to the protocol to allow participants to become more accustomed to the unique testing procedures