Comparison of longitudinal biomechanical adaptation to shoe degradation between the dominant and non-dominant legs during running.

This study compared the biomechanical adaptation to running shoe degradation between the dominant (D) and non-dominant (ND) leg. Twenty-four runners performed a pre-test in the laboratory, completed 200 miles of road running in a pair of assigned shoes and then returned for a post-test. Kinetic and kinematic data of running in new and worn shoes were collected. Repeated measures ANOVA (Shoe×Leg) were used to analyze temporal, kinetic and kinematic variables (α=.05). A symmetry index (SI) was calculated for the temporal and kinetic variables and paired t-tests were used to compare the SI between shoe conditions. Stance time increased by approximately 7 ms in worn shoes (p=.027). Bilateral differences in the kinematic change (Shoe×Leg interaction) were seen in the torso (p<.05), knee (p<.05), marginally at the hip (p<.10) but not the ankle. No difference in kinetic variables or SI was observed. When running in worn shoes, the torso displayed reduced forward lean for both sides and to a greater extent during the D leg strike. The D hip and knee showed a more extended position for the worn shoe condition while an increased flexion was observed in the ND leg. Most of the kinematic differences observed were small and within the intra-subject variability measured during the same session. Future studies may consider performing a three-dimensional analysis at a higher sample rate and further explore whether asymmetrical adaptation is related to running injuries.

Spanning set may not be appropriate for measuring knee kinematic variability for the entire gait cycle during over-ground barefoot running.

This study aimed to 1) determine the suitability of using spanning set (SS) to measure knee angle variability in the entire gait cycle and 2) assess the sensitivity of SS magnitude to the order of polynomial fitted to the standard deviation (SD) curves of the mean ensemble curves. Eight runners performed 10 over-ground barefoot running trials, followed by 8 min of accommodation, and then another 10 trials. Knee angle variabilities before and after accommodation were assessed using the SS and two conventional methods: mean coefficient of variation and mean SD. The sensitivity of the SS magnitude was assessed by calculating SS using (n-2), (n-1), (n+1), and (n+2)th orders of polynomials, where nth is the best fit order. Variability decreased after accommodation using the conventional methods (p < .05) but not the SS. The SS magnitude was sensitive to the order of polynomial. It is concluded that the SS may not be appropriate for measuring knee kinematic variability in the entire gait cycle during over-ground barefoot running.

Effects of manual resistance training on fitness in adolescents.

Manual resistance training (MRT), an alternative to traditional resistance training, requires minimal equipment and may be effective when applied in school-based physical education (PE) classes. The purpose of this study was to document the physical changes in adolescents (n = 222) using MRT in school-based PE settings. Six fitness tests from the Fitnessgram assessment tool were selected to assess students' cardiovascular and muscular fitness, and skinfold tests were used to assess body composition. One control and 2 experimental groups were defined. The control group of students (n = 129) attended regular PE classes. One experimental group (n = 63) attended PE that was complemented by the MRT system. A second experimental group (n = 30) attended PE complemented by MRT and cardiovascular endurance training. With use of the selected Fitnessgram tests, post-test measurements were performed after 9 and 18 weeks of PE. At baseline, there were no significant differences among the 3 groups for most measures. Compared with baseline, the experimental groups improved significantly in all 6 fitness measures and showed more improvements than the control group in most fitness measures both at 9 and 18 weeks. None of the groups showed significant improvement in body composition. The results documented that an MRT-complemented PE program was effective in improving adolescents' muscular fitness. An 18-week combined MRT and cardiovascular endurance training program effectively improved cardiovascular and muscular fitness but was ineffective in improving adolescent body composition. An MRT-based exercise session requires minimal equipment and set-up and can be performed in a short period of time, and therefore it is suitable for application in regular PE settings.

Perception of self-selected running speed is influenced by the treadmill but not footwear.

In this study, we examined whether self-selected overground running speed was consistent (1) with perceived overground speed on the treadmill and (2) among barefoot and three footwear conditions. Participants ran across a 20-m runway 10 times for each overground condition, with running speed calculated from kinematic data. For the treadmill condition, the participants were instructed to run at a speed that felt similar to their overground speed. This treadmill speed was chosen upon perception, with the display covered from the participant's view. Repeated-measures analysis of variance was used to detect differences in speed between overground and treadmill running, and also among barefoot and footwear conditions. Coefficient alpha (alpha) was calculated to determine repeatability of observations in each overground condition. The speed was higher during overground (3.65 +/- 0.40 m/s) than treadmill (2.25 +/- 0.75 m/s) running but did not differ among the barefoot and the three footwear conditions. Overall, overground speed was highly repeatable within an individual (alpha = 0.96-0.98). Researchers might consider using self-selected speed when investigating overground running mechanics with different foot-ground interface conditions. The influence of treadmill on the perception of speed may be related to shear force, running duration, joint load control, and/or other psychological factors.