Results (continued)

Results

Abstract

Methods

The motor imagery group was read a detailed script and in summary asked to do the following during rest intervals:1.Picture their form2.Visualize the internal changes occurring 3.Kinesthetically feel the bench press execution.

Methods (continued)

Purpose

Conclusions

Janet Pacheco The University of Texas at Arlington: Kinesiology Research Laboratory. Spring 2014

The Benefits of Motor Imagery on Upper Limb The Benefits of Motor Imagery on Upper Limb StrengthStrength

The purpose of this study was to determine the effects of motor imagery on upper limb strength.

Eleven college males (ages: 22.1± 0.3yrs), accepted to participate in this study, but only ten completed the entire study. There were two groups a motor imagery group (MI) and a control group; both of which adhered to an exact training protocol with the only exception of either a neutral rest or motor imagery rest in between bench press sets. Participants had a total of 7 sessions each. Each subject had anthropomorphic measurements assessed on their first visit. Circumferences of the upper/lower chest and right arm were recorded. Their demographic data (Table 1) was also collected in the initial visit. Each subject performed two-baseline test prior to the three training sessions. The four variables assessed were MVC, MR, circumference, and a questionnaire. The statistical analysis used to analyze the difference amongst the two groups was determined by the t test.

INTRODUCTION: Motor Imagery (MI) is a dynamic state in which an individual mentally stimulates a given action, without an actual motor output. The primary function is to allow the individual to generate a specific predetermined and possible outcome based on past experiences. A generous portion of MI research is primarily focused on rehabilitation rather than a strength training setting. In many cases when a patient is unable to execute a physical movement, the next most relevant scenario is to visualize the execution of that specific movement. Research suggests an increase in strength may be due to an improvement of the motor skill and their neural adaptations when using MI in junction with physical practice. MI for the purposes of this study will consist of having the participants visualize themselves bench-pressing in between their sets. They are prompted to not only imagine the given sets but to also be kinesthetically aware of their body during their rest intervals.  PURPOSE: The purpose of this study was to determine the effects of motor imagery on upper limb strength.  METHODS: Ten college males (age 22.1± 0.3yrs), volunteered to participate in this study. Each subject had anthropomorphic measurements assessed by circumferences of the upper/lower chest and right arm. Each subject performed two-baseline test prior to the three training sessions. The first was a maximal voluntary contraction (MVC), followed by a maximal repetitions (MR) session at 80% of their MVC. These values were both recorded and after 3 training sessions, the posttest values were acquired by using the same baseline test.  RESULTS: The circumferences for the three sites were as follows: upper chest (41 ± 1.2 in), lower chest (39 ± 1.2 in), and right arm (13.8 ± 0.72 in). The height of (70.4 ± 1.12 in) and weight of (182 ± 15.6 lbs.) are all values for the control group. For the experimental group the values were as follows: upper chest (41.8 ± 2.16 in), lower chest (40 ± 2.4in), and right arm (15 ± 0.8 in); height (69.8 ± 2.64 in) and weight (184.6 ± 23.12lbs). No significant difference was observed in any of these values( p > 0.05) . The difference between the control group’s pre and post testing was not statistically significant (p > 0.05). No change was seen in pre and post testing for MR (p> 0.05). The same occurred with the pre and post testing of the control group. However, there was a statistically significant difference (p = 0.0001) between the changes of the two groups (p < 0.05).CONCLUSION: The results of this study indicate that strength gains (primarily MVC) may be seen when incorporating MI training during rest time in between physical training sets.  

Table 1. Subject Demographics

Although there was a slight increase of maximal reps for the control group when compared to the MI group; there was no statistical significant difference (p > 0.05). The control group increased their MR by (3 ± 2lbs), and the experimental group by (1.8 ± 0.64lbs). There was also no change seen in the anthropomorphic measures taken pre and post test for neither group (p > 0.05).

Figure 1: MI Subject Performing Post Maximal Voluntary Contraction

Age (yrs.) Weight (lbs.) Height (in)

Experimental 22.4 ± 0.48 182 ± 15.6 70.4 ± 1.12

Control21.8 ± 1.04 184.6 ± 23.12 60.8 ± 2.64

Upper Chest (in.) Lower Chest (in.) Right Arm (in.)

Experimental41.8 ± 2.16

40 ± 2.4 15 ± 0.8

Control41± 1.2 39 ± 1.2 13.8 ± 0.72

Table 2: Subject Circumferences (Pre-test)

The primary objective of this study was to investigate the effects of MI training on strength of the upper body. The main result established was that by incorporating MI training during the rest in between sets, will improve MVC of bench press. Previous literature argues the efficacy of MI training being due to increase activation of the pre-frontal cortex. This theory states that by continuously rehearsing a motor skill will allow for neural pathways of the brain to the muscle to be fortified. An exclusive selection of participants were recruited for the purposes of this study. All participants were required to have a minimum of 2 years of experience in weight training. The requirement was placed to avoid improvement of strength resulting from a learning curve perspective. It should also be noted that this study spanned under a 6 week period; thus not allowing sufficient time for drastic morphological changes. The MI subjects all increased their MVC in less than 20 days. Therefore, making strength gains being due to hypertrophy improbable. To ensure the absence of hypertrophy, body circumferences were taken and confirmed no significant change in body structure. Based on the findings of this study and with the selected population; the data indicates that strength gains (primarily MVC) of bench press may be seen when incorporating MI training during rest time in between physical sets.

Each participant in the MI group increased their MVC by (17 ± 3.6 lbs.). This was a drastic increase when compared to the control group, which actually decreased by (2 ± 2.4 lbs.). The fact that this was observed in only 3 training sessions was a substantial outcome.

Session 1: MVC assessmentSession 2: MR at 80% of MVCSession 3: 4x3 at 90% of MVC; M.I group in addition integrates: 7x3 mental sets in between rest. Session 4: 4x3 at 95% of MVC; M.I. group in addition integrates: 8x3 mental sets during rest.Session 5: (1x95%, 2x90%, 3x85%, 5x80%, and 7x75% of MVC); M.I. group in addition integrates: 15x1, 10x2, 8x3, 4x5, and 3x7 mental sets during rest. Session 6: Post MVCSession 7: Post MR