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Christian A. Clermont, Lauren C. Benson, W. Brent Edwards, Blayne A. Hettinga and Reed Ferber

Running has become one of the most common sports and recreational activities around the world. The sport is also growing each year, where more people than ever are beginning to explore running trails for the first time due to the increased interest in more recreational, unorganized, and lighter

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Katherine A. Boyer, Julia Freedman Silvernail and Joseph Hamill

Injury rates among runners are high, with the knee injured most frequently. The interaction of running experience and running mechanics is not well understood but may be important for understanding relative injury risk in low vs higher mileage runners. The study aim was to apply a principal component analysis (PCA) to test the hypothesis that differences exist in kinematic waveforms and coordination between higher and low mileage groups. Gait data were collected for 50 subjects running at 3.5 m/s assigned to either a low (< 15 miles/wk) or higher (> 20 miles/wk, 1 year experience) mileage group. A PCA was performed on a matrix of trial vectors of all force, joint kinematic, and center of pressure data. The projection of the subjects’ trial vectors onto the linear combination of PC7, PC10, PC13, and PC19 was significantly different between the higher and lower mileage groups (d = 0.63, P = .012). This resultant PC represented variation in transverse plane pelvic rotation, hip internal rotation, and hip and knee abduction and adduction angles. These results suggest the coordination of lower extremity segment kinematics is different for lower and higher mileage runners. The adopted patterns of coordinated motion may explain the lower incidence of overuse knee injuries for higher mileage runners.

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Sam T. Johnson, Grace M. Golden, John A. Mercer, Brent C. Mangus and Mark A. Hoffman

Context:

Form skipping has been used to help injured athletes progress to running. Because little research has been done on form-skipping mechanics, its justification as a progression to running exercises is unclear.

Objective:

To compare ground-reaction forces (GRF) during form skipping and running in healthy subjects at clinically relevant speeds, 1.75 m/s and 3.83 m/s, respectively.

Design:

Dependent t tests (α = .05).

Setting:

Sports-injury research center.

Participants:

9 male college athletes (age 20 ± 1.33 years, mass 848.4 ± 43.24 N, height 1.80 ± 0.07 m).

Main Outcome Measures:

Average (Fz avg) and maximum (Fz max) vertical GRF and (Fy) braking impulse were compared.

Results:

Fz avg and Fz max were greater during running than during form skipping (P < .05). Braking impulses were not different (P > .05).

Conclusions:

It appears that Fz, but not the Fy, GRF might explain why form skipping might be an appropriate progression to running.

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Oleg Verbitsky, Joseph Mizrahi, Arkady Voloshin, July Treiger and Eli Isakov

The goal of this research was to analyze the effects of fatigue on the shock waves generated by foot strike. Twenty-two subjects were instrumented with an externally attached, lightweight accelerometer placed over the tibial tuberosity. The subjects ran on a treadmill for 30 min at a speed near their anaerobic threshold. Fatigue was established when the end-tidal CO2 pressure decreased. The results indicated that approximately half of the subjects reached the fatigue state toward the end of the test. Whenever fatigue occurred, the peak acceleration was found to increase. It was thus concluded that there is a clear association between fatigue and increased heel strike–induced shock waves. These results have a significant implication for the etiology of running injuries, since shock wave attenuation has been previously reported to play an important role in preventing such injuries.

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Christopher L. MacLean, Irene S. Davis and Joseph Hamill

The purpose of this study was to analyze the influence of varying running shoe midsole composition on lower extremity dynamics with and without a custom foot orthotic intervention. Three-dimensional dynamics were collected on 12 female runners who had completed 6 weeks of custom foot orthotic therapy. Participants completed running trials in 3 running shoe midsole conditions—with and without a custom foot orthotic intervention. Results from the current study revealed that only maximum rearfoot eversion velocity was influenced by the midsole durometer of the shoe. Maximum rearfoot eversion velocity was significantly decreased for the hard shoe compared with the soft shoe. However, the orthotic intervention in the footwear led to significant decreases in several dynamic variables. The results suggest that the major component influencing the rearfoot dynamics was the orthotic device and not the shoe composition. In addition, data suggest that the foot orthoses appear to compensate for the lesser shoe stability enabling it to function in a way similar to that of a shoe of greater stability.

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Ping Xiang, Ron McBride and April Bruene

Using achievement goal theory and the expectancy-value model of achievement choice as theoretical frameworks, this study examined relationships between parents’ beliefs and their children’s motivation in an elementary physical education running program. Participants included 102 parents and their children (49 boys; 53 girls) in the third and fourth grades. The parents completed questionnaires assessing their achievement goals, competence beliefs, task values, and gender stereotypic beliefs about running. Children’s persistence/effort was assessed by the number of laps run/walked over the year-long running program. Performance was measured by the timed mile run. Results indicated that only parents’ competence/value beliefs were predictive of their children’s persistence/effort and mile run performance. Gender stereotypic beliefs influenced achievement goals the parents adopted for their children. Findings provided empirical support for the importance of parental beliefs for children’s motivation in physical activity.

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Jonathan Sinclair, Sarah J. Hobbs, Paul J. Taylor, Graham Currigan and Andrew Greenhalgh

In running analyses where both kinetic and kinematic information is recorded, participants are required to make foot contact with a force and/or pressure measuring transducer. Problems arise if participants modify their gait patterns to ensure contact with the device. There is currently a paucity of research investigating the influence of different underfoot kinetic measuring devices on 3-dimensional kinematics of running. Fifteen participants ran at 4.0 m/s in four different conditions: over a floor embedded force plate, Footscan, Matscan, and with no device. Three-dimensional angular kinematic parameters were collected using an eight camera motion analysis system. Hip, knee, and ankle joint kinematics were contrasted using repeated-measures ANOVAs. Participants also rated their subjective comfort in striking each of the three force measuring devices. Significant differences from the uninhibited condition were observed using the Footscan and Matscan in all three planes of rotation, whereas participants subjectively rated the force plate significantly more comfortable than either the Footscan/Matscan devices. The findings of the current investigation therefore suggest that the disguised floor embedded force plate offers the most natural running condition. It is recommended that analyses using devices such as the Footscan/Matscan mats overlying the laboratory surface during running should be interpreted with caution.

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Brigit De Wit and Dirk De Clercq

This study investigates the timing differences between subtalar and knee joint movement of 9 male subjects while running barefoot and shod at three velocities. An alternative approach is used by dividing the pronation curve into 3 phases. Consequently, the timing of the maximum pronation phase was evaluated, not just the event of the maximum pronation value. Statistical differences were tested using the General Linear Method and paired t tests (p £.05), The extension of the knee starts both barefoot and shod significantly earlier than the resupination phase. Individual analysis shows that a larger time discrepancy between knee extension and the end of pronation mainly depends on the presence of bimodal pronation curves. The relative time differences significantly diminish with increased running velocity. Results suggest that by using this alternative approach, more detailed and useful information is available to describe the lime relationship between flexion-extension of the knee and pro-supination.

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Brigid Byrd and Jeffrey J. Martin

The purpose of this cross sectional study was to predict feelings of belonging and social responsibility based on climate perceptions of youth participating in a middle school running program. Method: Seventy-four youth from a middle school track and cross country program in the Midwest participated. Results: Based on multiple regression analyses we predicted 52% of the variance in feelings of belonging largely due to perceptions of leadership emotional support and task climate and 25% of the variance in feelings of social responsibility largely due to perceptions of a caring climate. Conclusions: Our findings support the importance of middle school running programs which offered an environment allowing multiple psychosocial benefits, such as nurturing feelings of belonging and social responsibility.

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Adam C. Clansey, Mark J. Lake, Eric S. Wallace, Tom Feehally and Michael Hanlon

The purpose of this study was to investigate the effects of prolonged high-intensity running on impact accelerations in trained runners. Thirteen male distance runners completed two 20-minute treadmill runs at speeds corresponding to 95% of onset of blood lactate accumulation. Leg and head accelerations were collected for 20 s every fourth minute. Rating of perceived exertion (RPE) scores were recorded during the third and last minute of each run. RPE responses increased (P < .001) from the start (11.8 ± 0.9, moderate intensity) of the first run to the end (17.7 ± 1.5, very hard) of the second run. Runners maintained their leg impact acceleration, impact attenuation, stride length, and stride frequency characteristics with prolonged run duration. However, a small (0.11–0.14g) but significant increase (P < .001) in head impact accelerations were observed at the end of both first and second runs. It was concluded that trained runners are able to control leg impact accelerations during sustained high-intensity running. Alongside the substantial increases in perceived exertion levels, running mechanics and frequency domain impact attenuation levels remained constant. This suggests that the present trained runners are able to cope from a mechanical perspective despite an increased physiological demand.