Project Title: Influence of Experience and Attentional focus on the Kinetics, Kinematics, and Ground Reaction Force of a Barbell Back Squat.
Part 1 - Press Summary
Describe your proposed research project using language that a non-specialist will be able to understand. You will be evaluated here exclusively on your ability to provide a comprehensive and clear description of your proposed project that someone outside of your field can understand. Avoid disciplinary jargon! Please see the guidelines for proper faculty mentor roles in helping prepare this, and other all pieces of the application.
- What question(s) are you trying to address?
How do lower back and limb joint angles (kinematics) and joint forces (kinetics) in a barbell back squat (BBS) differ under control, external, and internal focus conditions in experienced and novice weightlifters?
How does an internal versus an external attentional focus impact the force a lifter’s feet exert on the ground (ground reaction force) in a BBSin novice and experienced populations?
- How is your project important to your field and the broader community?
The proposed research will address whether attentional focus impacts the kinematics, kinetics, and ground reaction force in a BBS. Since the BBS is widely used to increase lower body strength, the impact of attentional focus on the above-mentioned variables is important in helping individuals reach resistance training goals. Gaining insight into the proper instruction of individuals will also help prevent injury.
- How will you address the question(s) that you pose above in question (a.)? What will your methodology be?
The impact of an external focus (pushing the floor away from the body) vs and internal focus (putting pressure on the outside of the foot and heel) on ground reaction force (GRF)will be measured using force plates for groups with less than six months and more than three years of weight training experience. The joint kinetics and kinematics of the squat will be assessed for both groups using the software Motion Monitor.
- What would you predict will be the outcomes of your research? What are the possible alternate outcomes? How will you interpret the results?
Previous research found an external focus to yield significantly higher force output over an internal focus for experienced populations, but this was not seen in novices. I expect the same resultto be seen in GRF.
Improved jumping kinetics accompanied increased maximum jump height due to an external focus. Proper kinetics are correlated with proper kinematics; thus, I expect both variables to improve in both groups when an external focus is adopted.
Given that previous research was done on a single joint movement, an external focus may yield significantly higher force output for both groups. Additionally, novices may not see improved kinematics and kinetics with an external focus given that literature has focused on experienced populations.
Statistical analysis will be done in order interpret whether focus conditions and experience impact outcome variables.
- How will you disseminate the results of your research? If applicable, please describe how your research is part of a broader project designed for publication and/or presentation at a major academic meeting.
I will present at the Inquiry at UST and submit my research to the American College of Sports Medicine annual meeting in the spring 2018. Furthermore, I will pursue publication in a sports medicine journal.
- What do you think will be the impact of your research on your academic and intellectual development? How will conducting this research contribute to your longer-term academic and professional goals?
As a pre-chiropractic exercise science major, this study is applicable to my undergraduate education. Additionally, this study has potential to give insight into proper exercise instructionin novices and will be helpful when instructing future patients.
PART 2 - Project Narrative(
1. Research Question
What question(s) are you planning to address in your research?
How do lower back and limb joint kinetics and kinematics in a standardized barbell back squat (BBS) differ under control, external focus, and internal focus conditions in experienced and novice weightlifters?
How does an internal versus an external attentional focus impact ground reaction force output in a barbell back squat in novice and experienced performers?
2. Background and Literature Review
What is the background of your project? Why is your project important to your discipline and to the general community? What have scholars written about your project/question(s) in the past? Who are the most important researchers relating to your project? How does your project fit in with the existing literature?
Whether climbing stairs, throwing a ball or a performing a squat, complex human body movementsrequire combinations of motor skills. A motor skill is a sequence of intentional muscular contractions and joint movements intended to effectively perform a movement and achieve a goal. In carrying out motor skills, the performer can direct his (or her) attention externally towards the task outcome or internally towards the movement used to achieve a goal. For instance, a basketball player can focus attention on the basketball hoopor the movement of his arm while shooting free throw. Which focus is adopted may importantly impact the performance of the skill.
Research has shown that directing attention to the movement (i.e., external focus), rather than to an individual’s own body (i.e., internal focus) positively affects performance (Wulf, Hob, and Prinz, 1998). With regards to sport skills, evidence suggests directing attentionalfocus externally toward the outcome of the movement is positively associated with motor performance accuracyand skill acquisition.When accuracy is important, several studies have shown adopting an external focus (i.e., focusing on the target rather than the arm muscles performing the action) results in improved motor skill learning and performance in dart throwing, basketball free throw shooting, and golfers’ putting (Lohse et al., 2010; Zachry et al., 2005; Land et al., 2014). While it appears that an external focus may be beneficial for performance of a motor skill, little is known of the impact shifts in attentional focus have on how the body moves and generates muscle force to perform the motor skill.
Shifts in attentional focusmay also influence movementjointkinematicsand kinetics. Joint kinematics are the movements of the joint and joint kinetics are the forces acting on the joint which cause it to move. Unlike learningand performance of motor skills, attentional focused-based differencesin joint kinematics appear to vary from movement to movement.For example,the elbow kinematics of dart throwing (anaccuracy-based movement skill) are not impacted by shifts in attentional focus (Lohse et al., 2010),but this does not appear to be true of primal movement (i.e., squatting, running, jumping)kinematics. Gokeler et al. (2015) found that an external focus improvedknee joint kinematics in a single-leg jump performed by patients following ACL reconstruction surgery. Similarly,thelower body kinetics of jumping are positively impacted by an external focus (Wulf and Dufek, 2009). In conclusion, the impact of attentional focus on joint kinetics and kinematics in performance accuracy tasks is variable; while, changes in attentional focus significantly impact the same variables in activities based on primal movements.
Attentional focus should play an important role when performing activitiessuch as weight lifting, where increased force output is a goal. For example, Marchant et al (2009) found significantly greater bicep brachiimuscle force production during an external compared to internal focus condition a single arm elbow flexion movement among physically-trained participants. Lower body ground reaction force(GRF; the force the ground exerts on a bodypart) is positively impacted by adopting an external focus. For example, Wulf et al. (2010) found greater jump-and-reach height, a measure ofGRF, among participantswho externally focused attention on the object they were jumping to reach, rather than focusing internally on the body movements used to jump.These studies suggest that force output in weight lifting movements may be positively impacted by an external focus. What remains unknownis howattentional focus and participant experience level affectjoint movements and muscle force output duringcomplex weight-lifting movements.Thus, the aim of this study is to determine the influence of attentional focus on GRF and lower body joint kinetics and kinematics during a barbell back squat among novice and experienced weight lifters.
3. Research Design and Methodology
How will you address the question(s) that you pose? What methodologies will you employ? How do you plan to analyze your results?
In this cross-sectional study, 40 male participants (18-64 years or age) will be recruited from Northwestern Health Sciences University (Bloomington, MN) and the surrounding metro area and divided into two groups: Novice (n=20) with less than six months of resistance training experience and Experienced (n=20) with more than three years of resistance training experience focusing on muscle hypertrophy.Participants will be excluded in they have a current orprevious injury that results in the inability to painlessly perform a weighted squat motion. Participants will be asked to abstain from maximum effort training involving a squat movement 48 hours prior to data collection and maintain caffeine consumption at a consistent level.
Dependent Variables:
- Ground reaction force (Newtons)will be obtained usingBertecforce plates.
- Joint kinematics (degrees), kinetic moment (Newton meters/kilogram), and kinetic power (Watts/kilogram)for the ankles, knees, hips, pelvis, and lower back will be obtained using the software Motion monitor.
Conditions:
Participants will perform a 5-10 minutewarmup consisting of walking on a treadmill at a self-selected pass and a series of bodyweight squats to prepare them for exercise and acclimate them to the focus condition. The amount of weight individuals will lift will be based on individual one repetition maximum. Participants will perform one set ofeight repetitions of a BBS at 70% of their one repetition maximum. They will visit the laboratory for three separate visits: a control (only task goal provided) followed by counterbalanced internal(putting pressure on the outside of the foot and heel) and external (pushing the floor away from the body) focus conditions; a minimum of 48 hours will separate each visit.
A two-way analysis of variance (ANOVA) statistical test will be used to compare the mean differences of the dependent variables between the novice and experienced groups and between study conditions.
4. Results and Interpretation
What would you predict will be the outcomes of your research and what are some possible alternate outcomes? How will you interpret the results?
Previous research found an external focus to yield significantly higher force output over an internal focus for experienced populations, but this was not seen in novices. I expect the same result to be seen in GRF.
Improved jumping kinetics accompanied increased maximum jump height due to an external focus. Proper kinetics are correlated with proper kinematics; thus, I expect both variables to improve in both groups when an external focus is adopted.
Given that previous research was done on a single joint movement, an external focus may yield significantly higher force output for both groups. Additionally, novices may not see improved kinematics and kinetics with an external focus given that literature has focused on experienced populations.
A two-way ANOVA will be done in order interpret whether focus conditions and experience impact outcome variables.
5. Anticipated Impact
What do you think will be the impact of your research on your discipline, the general community, and your own intellectual development?
The squat is widely used in sports, recreational resistance training, and injury rehabilitation. Thus, learning to better instruct novice and experienced populations to perform this exercise is important. As a pre-chiropractic exercise science major, this study is applicable to my undergraduate education. Additionally, gaining insight into proper exercise instruction will be helpful when educatingmy future patients.
.
6. Dissemination Plan
How will you share the results of your research? What specific conferences might you attend? What audiences do you hope to reach?
I will present at the Inquiry at UST and submit my research to the American College of Sports Medicine annual meeting in the spring 2018. Furthermore, I will pursue publication in a sports medicine journal.
Part 3 - Project Timeline
June 7- June 21: Recruitment and scheduling of participants
June 14- July 26: Data collection
July 26 – August 2: Data analysis
August 2- August 16: Gathering materials and creating poster
Part 4 - Additional Appendices
Appendix A: Glossary
Kinematics: pertaining to how points on an object move with no consideration for the force acting on them.
Kinetics: pertaining to how forces impact the movement of points on an object.
Ground reaction force: The force the ground exerts on any body part in contact with the ground. The ground reaction force is equal to the force the body part is exerting into the ground.
Appendix B: References
Gokeler, A., Benjaminse, A., Welling, W., Alferink, M., Eppinga, P., & Otten, B. (2015). The effects of attentional focus on jump performance and knee joint kinematics in patients after ACL reconstruction. Physical Therapy In Sport, 16(2), 114-120.
Land, W. M., Frank, C., & Schack, T. (2014).The influence of attentional focus on the …… development of skill representation in a complex action.Psychology Of Sport & Exercise, 15(1), 30-38.
Lohse, K.R, Sherwood, D.E, Healy, A.F., (2010). How changing the focus of attention affects performance, kinematics, and electromyography in dart throwing, HumMovSci,29(4), 542–555.
Marchant, D.C, Greig, M., Scott, C.(2009). Attentionalfocusinginstructionsinfluenceforce production and muscularactivity during isokineticelbowflexions.J Strength Cond Res, 23(8).
Wulf, G., Dufek, J., Lozano, L., Pettigrew, C. (2010) Increased jump height and reduced EMG activity with an external focus, Hum MovSci, 29(3), 440-8.
Wulf, G., Prinz, W., & Hob, M. (1998). Instructions for motor learning: Differential effects of.. Journal Of Motor Behavior, 30(2), 169.
Wulf, G., & Dufek, J. S. (2009). Increased Jump Height with an External Focus Due to Enhanced Lower Extremity Joint Kinetics. Journal Of Motor Behavior, 41(5), 401-409.