Motor imagery (MI) and action observation (AO) are techniques that have been shown to enhance motor skill learning. While both techniques have been used independently, recent research has demonstrated that combining action observation and motor imagery (AOMI) promotes better outcomes. However, little is known about the most effective way to combine these techniques. This study examined the effects of simultaneous (i.e., observing an action whilst imagining carrying out the action concurrently) and alternate (i.e., observing an action and then doing imagery related to that action consecutively) AOMI combinations on the learning of a dart throwing task. Participants (n=50) were randomly allocated to one of five training groups: action observation (AO), motor imagery (MI), simultaneous action observation and motor imagery (S-AOMI), alternate action observation and motor imagery (A-AOMI) and a control group. Interventions were conducted three times per week for six weeks and pre-and post-measures of total score were collected. Results revealed that all intervention groups, with the exception of the AO and control groups, significantly improved performance following the intervention. Posthoc analyses showed that S-AOMI group improved to a significantly greater degree than the MI and AO groups, and participants in the A-AOMI group improved to a significantly greater degree than the AO group. Participants in the A-AOMI group did not improve to a significantly greater degree than the S-AOMI group (p =1.00). These findings suggest that combining AOMI, regardless of how it's combined, may be the beneficial method for improving the learning and performance of aiming skills.

23The PETTLEP model of motor imagery (Holmes & Collins, 2001) has been shown 24 to be effective in enhancing strength performance. With recent literature discussing 25 the shared neural substrates between imagery and action observation, this study 26 investigated whether PETTLEP imagery would improve bicep strength both with 27 and without an additional observational aid. Using a single-case design, four 28 participants completed a baseline phase followed by PETTLEP imagery with and 29 without an observation aid in a counterbalanced manner. Weekly bicep curl 1 30 repetition maximum (1 R.M.) was used as the performance measure. Results 31 indicated that using an observational aid in conjunction with PETTLEP imagery 32 can aid performance, but not to a greater degree than PETTLEP imagery alone. This 33 indicates that observational aids may not be an essential addition to imagery 34 interventions, but their inclusion is not detrimental. The study highlights further the 35 benefit of using PETTLEP imagery for enhancing strength performance, which 36 should be considered by practitioners delivering resistance training programs. 37 Future research could further explore the role of observation when combined with 38 imagery to assess the effect on strength in an athletic population.39 40 41 42 43 3Motor imagery is the act of producing an internal representation of movement, typically 44 without generating any physical output (Mulder, 2007). Improvements in strength performance 45 following the use of motor imagery are well documented in the literature (see Slimani, Tod, 46 Chaabene, Miarka, & Charmari, 2016 for a review). For example, Yue and Cole (1992) found 47 that a four-week training program using either maximal isometric contractions or imagined 48 maximal isometric contractions produced strength gains of 29.8% and 22% respectively in the 49 abductor digiti minimi muscle. A more recent study (Wright & Smith, 2009) on a larger muscle 50 group (elbow flexors) also showed a strength gain of 23% through imagery training. 51Such findings are potentially of great value to those involved in strength training. 52However, the question of how to conduct imagery to produce optimal strength gains also needs 53 to be considered. The PETTLEP model (Holmes & Collins, 2001) has recently been used to 54 guide imagery interventions with strength tasks (for example, see Wakefield & Smith, 2011). 55This model was derived from a mix of cognitive psychology, sport psychology and 56 neuroscience research, the latter indicating that imagery produces activity in similar areas of 57 the brain to those active during movement execution. Consequently, the model proposed that a 58 'functional equivalence' exists between imagery and physical performance of a motor skill. 59PETTLEP is an acronym, with each letter standing for a practical consideration when designing 60 and constructing an imagery intervention. These are Physical, Environment, Task, Timing. 61

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