Alicia N. Abbey

Hamstring muscle kinematics and activation during overground sprinting

Hamstring muscle strain injury is one of the most commonly seen injuries in sports such as track and field, soccer, football, and rugby. The purpose of this study was to advance our understanding of the mechanisms of hamstring muscle strain injuries during over ground sprinting by investigating hamstring muscle-tendon kinematics and muscle activation. Three-dimensional videographic and electromyographic (EMG) data were collected for 20 male runners, soccer or lacrosse players performing overground sprinting at their maximum effort. Hamstring muscle-tendon lengths, elongation velocities, and linear envelop EMG data were analyzed for a running gait cycle of the dominant leg. Hamstring muscles exhibited eccentric contractions during the late stance phase as well as during the late swing phase of overground sprinting. The peak eccentric contraction speeds of the hamstring muscles were significantly greater during the late swing phase than during the late stance phase (p=0.001) while the hamstring muscle-tendon lengths at the peak eccentric contraction speeds were significantly greater during the late stance phase than during the late swing phase (p=0.001). No significant differences existed in the maximum hamstring muscle-tendon lengths between the two eccentric contractions. The potential for hamstring muscle strain injury exists during the late stance phase as well as during the late swing phases of overground sprinting.

Isokinetic Strength, Endurance, and Subjective Outcomes After Biceps Tenotomy Versus Tenodesis A Postoperative Study

Background: Similar subjective outcomes have been reported for tenotomy or tenodesis of the long head of the biceps. Few studies have reported on postoperative strength and endurance. Hypothesis: Biceps tenodesis results in superior subjective outcomes, strength, and endurance compared with tenotomy. Study Design: Cohort study; Level of evidence, 3. Methods: Participants completed isokinetic strength and endurance testing for elbow flexion and supination on the operative and nonoperative sides a minimum of 2 years after biceps tenotomy or tenodesis. Modified American Shoulder and Elbow Surgeons (MASES) and Single Assessment Numeric Evaluation (SANE) scores were obtained. The operative/nonoperative strength and endurance scores were compared for the tenotomy and tenodesis groups, with the nonoperative shoulder serving as the control for each participant’s operative shoulder. Change scores for strength and endurance were reported as percentage increase or decrease as compared with the nonoperative side. Change scores and MASES and SANE scores were compared between the 2 groups. The presence of a “popeye” deformity or pain at the tenodesis site was noted. Results: Thirty-five patients (19 tenotomy, 16 tenodesis) were studied. No significant difference was noted in postoperative MASES and SANE scores. Operative-side peak supination torque was significantly decreased relative to the nonoperative side in the tenotomy group, which had a significantly larger decrease in supination peak torque than did the tenodesis group on comparison of change scores. No significant difference was noted for peak flexion torque or flexion/supination endurance between operative and nonoperative sides in either group or between change scores for peak flexion torque or flexion/supination endurance in the tenotomy and tenodesis groups. Four tenotomy patients had a popeye deformity, 2 of whom reported painful cramping. Two patients had pain at the tenodesis site. Conclusion: Subjective outcomes are similar for patients treated with tenotomy and tenodesis. Tenotomy decreases supination peak torque relative to the nonoperative side and tenodesis.

Differences in plantar loading between training shoes and racing flats at a self-selected running speed

The purpose of this study was to examine the difference in plantar loading between two different running shoe types. We hypothesized that a higher maximum force, peak pressure, and contact area would exist beneath the entire foot while running in a racing flat when compared to a training shoe. 37 athletes (17 male and 20 female) were recruited for this study. Subjects had no history of lower extremity injuries in the past six months, no history of foot or ankle surgery within the past 3 years, and no history of metatarsal stress fractures. Subjects had to be physically active and run at least 10 miles per week. Each subject ran on a 10m runway 7 times wearing two different running shoe types, the Nike Air Pegasus (training shoe) and the Nike Air Zoom Katana IV (racing flat). A Pedar-X in-shoe pressure measurement system sampling at 50Hz was used to collect plantar pressure data. Peak pressure, maximum force, and contact area beneath eight different anatomical regions of the foot as well as beneath the total foot were obtained. The results of this study demonstrated a significant difference between training shoes and racing flats in terms of peak pressure, maximum force, and contact area. The significant differences measured between the two shoes can be of importance when examining the influence of shoe type on the occurrence of stress fractures in runners.

Effect of shoe type on plantar pressure: a gender comparison.

Despite the differences in materials, racing flats have begun to be used not only for racing, but also for daily training. As there are data suggesting a gender difference in overuse injuries in runners, shoe choice may affect loading patterns during running. The purpose was to determine differences in plantar pressure between genders when running in training shoes and racing flats. In-shoe plantar pressure data were collected from 34 subjects (17m, 17f) who ran over-ground in both a racing flat and training shoe. Contact area (CA), maximum force (MF), and contact time under the entire foot and beneath eight foot regions were collected. Each variable was analyzed using a shoe by gender repeated measures ANOVA (alpha=0.05). In men, MF was increased in the racing flats (p=0.016) beneath the medial midfoot (MMF), yet was increased beneath the medial forefoot (MFF) in the training shoe (p=0.018). Independent of gender, CA was decreased in the racing flats beneath the entire foot (p=0.029), the MMF (p=0.013), and the MFF (p=0.030), and increased beneath the lateral forefoot (LFF) (p=0.023). In the racing flats, MF was increased beneath the entire foot (p<0.001) and the LFF (p<0.001). Independent of the shoe, CA was decreased in men beneath the MFF (p=0.007) and middle forefoot (p<0.001), while MF was increased in the LFF (p=0.002). The LFF is an area of increased stress fracture risk in men. Based on the gender differences in loading, running shoe design should be gender specific in an attempt to prevent injuries.

Isokinetic testing of biceps strength and endurance in dominant versus nondominant upper extremities

BACKGROUND The strength and endurance of the contralateral biceps muscle can serve as a useful comparison for the operative limb following distal biceps repairs, mid-substance repairs, or tenotomy or tenodesis of the long head. There are limited data available on the effect of handedness on biceps strength and endurance. HYPOTHESIS The dominant upper extremity has greater elbow flexion and supination peak torque and endurance. MATERIALS AND METHODS Subjects with no history of prior upper extremity injury or limitations completed isokinetic testing of biceps flexion and supination peak torque and endurance on a Biodex machine. A paired student t test was used to compare peak torque and endurance for both supination and flexion for the dominant and nondominant upper extremities. The results were analyzed for the entire group, and for male and female subjects separately as well. RESULTS A power analysis revealed that 5 subjects were needed to achieve 80% power. Twenty subjects (10 male, 10 female) were tested. No significant difference was detected for peak torque or endurance for supination or flexion between the dominant and nondominant upper extremities. No difference was detected when the group was analyzed as a whole, nor when men and women were analyzed separately. CONCLUSIONS The dominant and nondominant upper extremities demonstrate similar peak torque and endurance for supination and flexion. The normal contralateral upper extremity can be used as a matched control in the evaluation of post operative biceps isokinetic strength and endurance without adjusting results for handedness.

Plantar Loading Comparisons Between Women With a History of Second Metatarsal Stress Fractures and Normal Controls

Background Stress fractures are common in athletics and are more prevalent in women. The current literature has not identified a reason for this gender difference. Hypothesis Women with a history of a second/third metatarsal stress fracture will demonstrate differences in loading in the middle forefoot. Study Design Controlled laboratory study. Methods Fifteen men, 15 control women, and 9 women with a history of a second/third metatarsal stress fracture were asked to run at 3.3 m/s ± 5% along a 10-m runway. Plantar loading parameters were recorded using a Pedar-X system. Results The women with fractures demonstrated a decrease in contact area and maximum force beneath the middle forefoot when compared with the female controls. Men demonstrated a decreased contact area in the medial and middle forefoot when compared with the control women. In addition, the women with fractures had decreased maximum force in the middle forefoot when compared with the control women. Conclusions The decrease in maximum force in the middle forefoot in patients with a previous stress fracture could have resulted from gait alterations after the fracture. Therefore, prospective studies need to be completed to better understand the loading differences that could be used to predict stress-fracture injury risk. Clinical Relevance It is unclear whether plantar loading can be used as a predictor of stress-fracture injury risk as these patients were tested after a stress fracture.

Gait Symmetry: A Comparison of Hip Resurfacing and Jumbo Head Total Hip Arthroplasty Patients

Proponents of large femoral head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) have touted the potential for restoration of more normal hip kinematics. This study examined 20 patients (10 THA and 10 HRA patients) approximately 18 months after surgery. Subjects were evaluated at a self-selected pace, while bilateral spatial-temporal gait variables, hip flexion/extension kinematics, and ground reaction forces were collected. For both groups, swing time was increased on the surgical side, whereas peak hip flexion, peak extension, and flexion at heel strike were decreased. Peak hip extension and peak vertical ground reaction forces were decreased in THA subjects compared with HRA subjects. After a large-diameter THA or HRA, subjects do not display symmetric gait approximately 18 months postoperatively. Total hip arthroplasty subjects demonstrated restricted hip extension and reduced limb loading when compared with HRA subjects.

Differences in wrist mechanics during the golf swing based on golf handicap

OBJECTIVES Variation in swing mechanics between golfers of different skill levels has been previously reported. To investigate if differences in three-dimensional wrist kinematics and the angle of golf club descent between low and high handicap golfers. DESIGN A descriptive laboratory study was performed with twenty-eight male golfers divided into two groups, low handicap golfers (handicap = 0-5, n = 15) and high handicap golfers (handicap ≥ 10, n = 13). METHODS Bilateral peak three-dimensional wrist mechanics, bilateral wrist mechanics at ball contact (BC), peak angle of descent from the end of the backswing to ball contact, and the angle of descent when the forearm was parallel to the ground (DEC-PAR) were determined using an 8 camera motion capture system. Independent t-tests were completed for each study variable (α = 0.05). Pearson correlation coefficients were determined between golf handicap and each of the study variables. RESULTS The peak lead arm radial deviation (5.7 degrees, p = 0.008), lead arm radial deviation at ball contact (7.1 degrees, p = 0.001), and DEC-PAR (15.8 degrees, p = 0.002) were significantly greater in the high handicap group. CONCLUSION In comparison with golfers with a low handicap, golfers with a high handicap have increased radial deviation during the golf swing and at ball contact.

Three-dimensional ankle kinematics and kinetics during running in women

Stress fractures are common in athletics and are more prevalent in women. The current literature has not identified a reason for this gender difference. We hypothesized that females with a history of a second/third metatarsal stress fracture will demonstrate differences in ankle kinematics, kinetics and ground reaction forces when compared with a group of age-matched females with no stress fracture history. A total of 15 control females and nine females with a history of a second/third metatarsal stress fracture were asked to run at 3.3m/s+/-5% along a 10-m runway. Kinematics and kinetics were obtained using an 8-camera motion analysis system (240Hz) and two force plates (1200Hz). Significant differences existed in height and weight between the groups. No other statistically significant differences existed between the fracture group and the control group. Kinematic measurements do not differ significantly between women with a history of second/third metatarsal stress fracture and female control subjects. The reported kinematic and kinetic measurements do not appear to be influenced in subjects with metatarsal stress fractures, which likely result from the complex relationships between the joints in the foot and ankle. The development of second/third metatarsal stress fractures could result more from over training or changes in plantar loading instead of changes in lower extremity joint kinematics while running.

Stair Ascending and Descending in Hip Resurfacing and Large Head Total Hip Arthroplasty Patients

Large head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) are alternatives to standard THA that generally have head sizes larger than 36mm. This study examined 20 patients (10 large head THA and 10 HRA), at an average of 18months postoperatively, and 15 healthy control subjects during stair negotiation. Hip kinetic and kinematic variables and ground reaction forces were measured. The THA and HRA groups ascended the stairs with increased peak hip flexion angles and decreased hip extension angles as compared with controls. The operative groups also descended the stairs with decreased hip flexion moments. No differences between the operative groups were observed. Eighteen months postoperatively, patients with large head THA or HRA display abnormal flexion and extension during a physically-demanding task.