Effect of training volume on footstrike patterns over an exhaustive run

Running-Related Achilles Tendon Injury: A Prospective Biomechanical Study in Recreational Runners

There are relatively few running studies that have attempted to prospectively identify biomechanical risk factors associated with Achilles tendon (AT) injuries. Therefore, the aim was to prospectively determine potential running biomechanical risk factors associated with the development of AT injuries in recreational, healthy runners. At study entry, 108 participants completed a set of questionnaires. They underwent an analysis of their running biomechanics at self-selected running speed. The incidence of AT running-related injuries (RRI) was assessed after 1-year using a weekly questionnaire standardized for RRI. Potential biomechanical risk factors for the development of AT RRI injury were identified using multivariable logistic regression. Of the 103 participants, 25% of the sample (15 males and 11 females) reported an AT RRI on the right lower limb during the 1-year evaluation period. A more flexed knee at initial contact (odds ratio = 1.146, P = .034) and at the midstance phase (odds ratio = 1.143, P = .037) were significant predictors for developing AT RRI. The results suggested that a 1-degree increase in knee flexion at initial contact and midstance was associated with a 15% increase in the risk of an AT RRI, thus causing a limitation of training or a stoppage of running in runners.

Achilles tendon dimensions, ankle stiffness and footfall patterns in recreational runners

The main purpose of this study was to investigate the relationship among Achilles tendon (AT) dimensions, ankle joint stiffness, and footfall patterns in recreational rearfoot and non-rearfoot runners. Based on the foot strike index, a total of 107 runners were divided into rearfoot (47 females/40 males) and non-rearfoot runners (14 females/6 males). All participants had theirs AT dimensions (AT length, AT thickness, and AT moment arm) measured using a combination of ultrasound and motion capture systems. In addition, all performed running trials measured at self-selected speed in laboratory-neutral shoes. A partial correlation coefficient was used for correlations between the selected variables. The results revealed a significant relationship between ankle joint stiffness and level of footfall pattern in rearfoot (r = 0.232, p = 0.032) and non-rearfoot runners (r = -0.811, p < 0.001). The results also suggest a relationship between AT thickness and foot strike index (r = -0.486) in non-rearfoot runners. Runners whose footfall pattern is closer to the heel have greater ankle joint stiffness. Non-rearfoot runners whose footfall pattern is closer to the toe have a thinner AT. Non-rearfoot runners with thicker AT had greater ankle joint stiffness.

The effect of fatigue on the ankle and knee kinematics and kinetics in moderately and highly trained healthy non-rearfoot runners

The aim of this study was to compare selected ankle and knee kinematic and kinetic parameters before and a fter a prolonged exhaustive treadmill run between two groups of non-rearfoot footstrike pattern (NRFP) runners with different training volumes. Twenty-eight habitual NRFP runners were assigned to two groups based on their weekly training volume (Highly-trained (HT)/Moderately-trained (MT)). Participants underwent the VO2max test, and the exhaustive treadmill ran with biomechanical analysis at the beginning and the end. The two-way RMANOVA was used to assess differences between the groups and the phase of the run. A paired t-test was used for post-hoc analysis in case of significant interaction effect. Kinetic results showed significant group effect for ankle plantarflexion moment and hip external rotation moment (end-phase: both greater in MT group). Kinematic results showed significant group×phase interaction for ankle dorsiflexion angle (end-phase: greater in MT group) at initial contact (IC), peak knee flexion angle (end-phase: greater in MT group), and peak ankle eversion angle during the stance phase (end-phase: greater in HT group). Additionally, a group effect was found for knee flexion angle at IC (end-phase: greater in HT group). This study suggests that HT healthy NRFP runners may have less potential for increased biomechanical risk of AT overload during an exhaustive run.

Does the Achilles Tendon Influence Foot Strike Patterns During an Exhaustive Run?

The study purpose was to investigate whether there is a relationship between the Achilles tendon (AT) length, moment arm length, and the foot strike pattern (FP) change during an exhaustive run (EXR) in nonrearfoot FP runners. Twenty-eight runners were recruited and divided into 2 groups (highly trained/moderately trained) according to their weekly training volume. Participants underwent the graded exercise test, the EXR with biomechanical analysis at the beginning, and at the end, and the magnetic resonance imaging scan of the AT. Correlations were used to assess associations between FP change (value of the difference between end and beginning) and the selected performance and AT variables. AT length significantly correlated with the FP change according to foot strike angle (r = -.265, P = .049). The AT moment arm length significantly correlated with the FP change according to strike index during EXR (r = -.536, P = .003). Multiple regression showed that AT length was a significant predictor for the FP change according to foot strike angle if the second predictor was the graded exercise test duration and the third predictor was training group association. These results suggest that a runner's training volume, along with a longer AT and AT moment arm appear to be associated with the ability to maintain a consistent FP during EXR by nonrearfoot FP runners.