Matching Items (4)
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- All Subjects: kinesiology
- Creators: Hinrichs, Richard
- Resource Type: Text
Description
During the downswing all golfers must roll their forearms and twist the club handle in order to square the club face into impact. Anecdotally some instructors say that rapidly twisting the handle and quickly closing the club face is the best technique while others disagree and suggest the opposite. World class golfers have swings with a range of club handle twist velocities (HTV) from very slow to very fast and either method appears to create a successful swing. The purpose of this research was to discover the relationship between HTV at impact and selected body and club biomechanical characteristics during a driver swing. Three-dimensional motion analysis methods were used to capture the swings of 94 tour professionals. Pearson product-moment correlation was used to determine if a correlation existed between HTV and selected biomechanical characteristics. The total group was also divided into two sub-groups of 32, one group with the fastest HTV (Hi-HTV) and the other with the slowest HTV (Lo-HTV). Single factor ANOVAs were completed for HTV and each selected biomechanical parameter. No significant differences were found between the Hi-HTV and Lo-HTV groups for both clubhead speed and driving accuracy. Lead forearm supination velocity at impact was found to be significantly different between groups with the Hi-HTV group having a higher velocity. Lead wrist extension velocity at impact, while not being significantly different between groups was found to be positive in both groups, meaning that the lead wrist is extending at impact. Lead wrist ulnar deviation, lead wrist release and trail elbow extension velocities at maximum were not significantly different between groups. Pelvis rotation, thorax rotation, pelvis side bend and pelvis rotation at impact were all significantly different between groups, with the Lo-HTV group being more side bent tor the trail side and more open at impact. These results suggest that world class golfers can successfully use either the low or high HTV technique for a successful swing. From an instructional perspective it is important to be aware of the body posture and wrist/forearm motion differences between the two techniques so as to be consistent when teaching either method.
ContributorsCheetham, Phillip (Author) / Hinrichs, Richard (Thesis advisor) / Ringenbach, Shannon (Committee member) / Dounskaia, Natalia (Committee member) / Crews, Debra (Committee member) / Arizona State University (Publisher)
Created2014
Description
Humans moving in the environment must frequently change walking speed and direction to negotiate obstacles and maintain balance. Maneuverability and stability requirements account for a significant part of daily life. While constant-average-velocity (CAV) human locomotion in walking and running has been studied extensively unsteady locomotion has received far less attention. Although some studies have described the biomechanics and neurophysiology of maneuvers, the underlying mechanisms that humans employ to control unsteady running are still not clear. My dissertation research investigated some of the biomechanical and behavioral strategies used for stable unsteady locomotion. First, I studied the behavioral level control of human sagittal plane running. I tested whether humans could control running using strategies consistent with simple and independent control laws that have been successfully used to control monopod robots. I found that humans use strategies that are consistent with the distributed feedback control strategies used by bouncing robots. Humans changed leg force rather than stance duration to control center of mass (COM) height. Humans adjusted foot placement relative to a "neutral point" to change running speed increment between consecutive flight phases, i.e. a "pogo-stick" rather than a "unicycle" strategy was adopted to change running speed. Body pitch angle was correlated by hip moments if a proportional-derivative relationship with time lags corresponding to pre-programmed reaction (87 ± 19 ms) was assumed. To better understand the mechanisms of performing successful maneuvers, I studied the functions of joints in the lower extremities to control COM speed and height. I found that during stance, the hip functioned as a power generator to change speed. The ankle switched between roles as a damper and torsional spring to contributing both to speed and elevation changes. The knee facilitated both speed and elevation control by absorbing mechanical energy, although its contribution was less than hip or ankle. Finally, I studied human turning in the horizontal plane. I used a morphological perturbation (increased body rotational inertia) to elicit compensational strategies used to control sidestep cutting turns. Humans use changes to initial body angular speed and body pre-rotation to prevent changes in braking forces.
ContributorsQiao, Mu, 1981- (Author) / Jindrich, Devin L (Thesis advisor) / Dounskaia, Natalia (Committee member) / Abbas, James (Committee member) / Hinrichs, Richard (Committee member) / Santello, Marco (Committee member) / Arizona State University (Publisher)
Created2012
Description
Dancers tend to injure the anterior cruciate ligament in their left leg more often than the right. It is unclear whether this trend is due to biased choreography or if leg dominance and left versus right asymmetries are contributing factors. The purpose of this study was to investigate asymmetries between the left and right leg, in knee abduction during landing, hip external rotation (ER) and internal rotation (IR) strength, and hip ER and IR range of motion in dancers compared to non-dancers. This study aimed to determine whether these asymmetries can be linked to leg dominance, and if this puts one leg at higher risk for ACL injury. Ten dancers and eleven non-dancers performed three maximal effort countermovement vertical jumps off of two feet, as well as three maximal effort single leg jumps on each leg. Knee abduction angles during the landing phase of the jumps were calculated using motion capture data. Maximum isometric hip ER and IR strength was measured at 15, 30, 45, 60, and 90 of knee flexion, and hip ER and IR range of motion was measured at 90 of knee flexion. Contrary to the hypothesis, few significant differences were found between the left and right leg, as well as between dancers and non-dancers. Dancers exhibited significantly greater IR range of motion than non-dancers, and knee abduction angles were greater on the right than left leg during double leg jumps. This opposes the hypothesis that knee abduction angles would be greater in dancers on the left leg. However, significant positive correlations were found
between IR strength and knee abduction angles during single leg jumps on the left leg, suggesting that IR strength may be a contributing factor to knee valgus. Further studies may want to utilize qualitative analyses, more relevant jumping tasks, and a different marker set to elucidate asymmetries of the lower limbs that may truly be present.
between IR strength and knee abduction angles during single leg jumps on the left leg, suggesting that IR strength may be a contributing factor to knee valgus. Further studies may want to utilize qualitative analyses, more relevant jumping tasks, and a different marker set to elucidate asymmetries of the lower limbs that may truly be present.
ContributorsOberbillig, Megan (Author) / Wiley, Alexander (Committee member) / Hinrichs, Richard (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2013-05
Description
Most athletic or daily activities require the use of force production at a given velocity, in other words, power is needed to complete these activities. There are different methods for how this can be done, but the main two are heavy resistance training and plyometric training (Kawamori and Haff, 2004). However, resistance bands are another option of training that is available at a low cost and equipment needs. Resistance bands can also be used by athletes and elderly alike, but so far the benefits have barely been studied. Two participants were recruited to be followed as a case study. Both were of college age and were currently recreationally active with no health or musculoskeletal problems. Both participants were given a 35 lb. resistance band and instructed to do four different lower extremity exercises (three sets of four repetitions each) that were designed to target the muscles used for jumping. The study ran for five weeks, requiring three workouts per week separated by at least 24 hours. Participants were tested at three points; initial, halfway, and after all 15 workouts had been completed. Tests included measuring for changes in maximal vertical jump height as well as maximal broad jump. Results showed that both participants were able to increase their vertical jump and broad jump measurements from the initial testing day. Participant one had a 22.95% and 39.40% increase in broad jump and vertical jump respectively. Participant two had a 7.84% and 11.72% increase in broad jump and vertical jump respectively. Based on this study, it would appear that the power training program is effective in producing an increase in power based off the measured performance variables. There may be some effect from familiarity with testing protocol but most likely increased were caused by neural adaptation from speed aspect of program, as well as some increase in force production.
ContributorsBrown, Eric Preston (Author) / Harper, Erin (Thesis director) / Hinrichs, Richard (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2014-05