THE RELATIONSHIP BETWEEN VERTICAL STIFFNESS IN MAXIMAL AND SUBMAXIMAL HOPPING TESTS AND RUNNING PERFORMANCE IN YOUNG MIDDLEDISTANCE RUNNERS: A PILOT STUDY

This study investigated the relationship between vertical stiffness in the sub-maximal and maximal bilateral hopping test and middle-distance running performance in young middle distance runners. The longer distance running performance was more correlated with normalized vertical stiffness in sub-maximal hopping, Wile the sprint performance was statistically linked to vertical stiffness in maximal hopping. Vertical stiffness measured in combination of the sub-maximal and maximal hopping tests might be utilized as a useful indicator for middle-distance running performance. Accordingly, incorporating plyometric exercises, especially involving vertical motions, might benefit middle-distance running performance

No Effect of EVA and TPU Custom Foot Orthoses on Mechanical Asymmetries during Acute Intense Fatigue

From Crossref journal articles via Jisc Publications RouterHistory: epub 2023-03-11, issued 2023-03-11Article version: VoRPublication status: PublishedFunder: QNRF; FundRef: 10.13039/100008982; Grant(s): NPRP 4-760-3-217This study examined the impact of custom foot orthoses made of ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to a control condition (CON; shoes only), on mechanical asymmetries during repeated treadmill sprints. Eighteen well-trained male runners executed eight, 5-s sprints (rest: 25 s) on an instrumented motorized treadmill in three footwear conditions (EVA, TPU, and CON). We evaluated the group mean asymmetry scores using the ‘symmetry angle’ (SA) formula, which assigns a score of 0% for perfect symmetry and a score of 100% for perfect asymmetry. There was no condition (all p ≥ 0.053) or time (p ≥ 0.074) main effects, nor were there any significant time × condition interactions on SA scores for any variables (p ≥ 0.640). Mean vertical, horizontal, and total forces presented mean SA values (pooled values for the three conditions) of 2.6 ± 1.9%, 2.9 ± 1.6%, and 2.4 ± 1.8%, respectively. Mean SA scores were ~1–3% for contact time (1.5 ± 0.5%), flight time (3.0 ± 0.3%), step frequency (1.1 ± 0.5%), step length (1.9 ± 0.7%), vertical stiffness (2.1 ± 0.9%), and leg stiffness (2.4 ± 1.1%). Mean SA scores were ~2–6.5% for duration of braking (4.1 ± 1.6%) and propulsive (2.4 ± 1.0%) phases, and peak braking (6.2 ± 2.9%) and propulsive (2.1 ± 1.4%) forces. In well-trained runners facing intense fatigue, wearing custom foot orthoses did not modify the observed low-to-moderate natural stride mechanical asymmetries.pubpu

KINETIC ANALYSIS OF THE BLOCK START AND FIRST TWO CONTACTS IN SPRINTING

The purpose of this study was to examine the force production characteristics of the arms and each leg in the block start and in the first two contacts of the acceleration phase in sprinting. The set-up consisted of six force platforms embedded in an indoor running track. A total of 61 starts from 19 male international level athletes were collected during maximal effort starts and accelerations between 10m and 40m. The average time over 10m was 1.648 ±0.048 seconds, measured using a Laveg speed gun. Results indicated that the arms accounted for 13.9% of the vertical impulse and -2% to horizontal impulse, the front leg 69% and 60% and the rear leg 25 and 33% respectively. Peak vertical and horizontal forces (relative to BW) in the front leg and their associated RFD’s produced the strongest correlations with time over 10m (all p\u3c0.001)

Custom foot orthoses improve performance, but do not modify the biomechanical manifestation of fatigue, during repeated treadmill sprints

From PubMed via Jisc Publications RouterWe determined the effect of custom foot orthotics manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to a control condition (CON; shoes only) during repeated sprints on running mechanical alterations. Eighteen males performed eight, 5-s sprints with 25-s recovery on an instrumented sprint treadmill in three footwear conditions (EVA, TPU and CON). Mechanical data consisted of continuous (step-by-step) measurement of running kinetics and kinematics, which were averaged for each sprint for further analysis. Distance ran in 5 s decreased from first to last sprint (P < 0.001), yet with higher sprints 1-8 values for both EVA (P = 0.004) and TPU (P = 0.018) versus CON. Regardless of footwear condition, mean horizontal forces, step frequency, vertical and leg stiffness decreased from sprint 1 to sprint 8 (all P < 0.001). Duration of the propulsive phase was globally shorter for both EVA (P = 0.002) and TPU (P = 0.021) versus CON, while braking phase duration was similar (P = 0.919). In the horizontal direction, peak propulsive (P < 0.001), but not braking (P = 0.172), forces also decreased from sprint 1 to sprint 8, independently of conditions. Compared to shoe only, wearing EVA or TPU custom foot orthotics improved repeated treadmill sprint ability, yet provided similar fatigue-induced changes in mechanical outcomes.120inpressinpres

KINETIC COMPARISON OF THE SPRINT STARTS BETWEEN YOUTH AND SENIOR ELITE ATHLETES

The purpose of this study was to identify differences in force, impulse and power characteristics in block starts and first two contacts between youth academy (n=20) and elite senior male sprinters (n=17). Senior sprinters were significantly faster out of the blocks with a horizontal velocity of 3.35m/s ±0.15 compared to 3.14 ±0.16m/s, leading to 10m times of 1.64±0.045s and 1.706±0.06s respectively. Force application time of the arms, rear leg and front leg were significantly lower in the senior athletes (all

Acute intense fatigue does not modify the effect of EVA and TPU custom foot orthoses on running mechanics, running economy and perceived comfort

Ken Van Alsenoy - ORCID: Ken Van Alsenoy https://orcid.org/0000-0002-0430-965XWe determined whether fatigue modifies the effect of custom foot orthoses manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to standardized footwear (CON), on running mechanics, running economy, and perceived comfort. Eighteen well-trained, males ran on an instrumented treadmill for 6 min at the speed corresponding to their first ventilatory threshold (13.8 ± 1.1 km/h) in three footwear conditions (CON, EVA, and TPU). Immediately after completion of a repeated-sprints exercise (8 × 5 s treadmill sprints, rest = 25 s), these run tests were replicated. Running mechanics, running economy and perceived comfort were determined. Two-way repeated measures ANOVA [condition (CON, EVA, and TPU) × fatigue (fresh and fatigued)] were conducted. Flight time shortened (P = 0.026), peak braking (P = 0.016) and push-off (P = 0.032) forces decreased and vertical stiffness increased (P = 0.014) from before to after the repeated-sprint exercise, independent of footwear condition. There was a global fatigue-induced deterioration in running economy (− 1.6 ± 0.4%; P < 0.001). There was no significant condition × fatigue [except mean loading rate (P = 0.046)] for the large majority of biomechanical, cardio-respiratory [except minute ventilation (P = 0.020) and breathing frequency (P = 0.019)] and perceived comfort variables. Acute intense fatigue does not modify the effect of custom foot orthoses with different resilience characteristics on running mechanics, running economy and perceived comfort.https://doi.org/10.1007/s00421-022-04903-9122pubpu

The effect of EVA and TPU custom foot orthoses on running economy, running mechanics, and comfort

Custom made foot orthoses (CFO) with specific material properties have the potential to alter ground reaction forces but their effect on running mechanics and comfort remains to be investigated. We determined if CFO manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to standardized footwear (CON), improve running economy (RE), running mechanics, and comfort at two running speeds. Eighteen well-trained, male athletes ran on an instrumented treadmill for 6min at high (HS) and low (LS) speeds corresponding to and 15% lower than their first ventilatory threshold (13.8 ± 1.1 and 11.7 ± 0.9 km.h−1, respectively) in three footwear conditions (CON, EVA, and TPU). RE, running mechanics and comfort were determined. Albeit not reaching statistical significance (P = 0.11, ! 2 = 0.12), RE on average improved in EVA (+2.1 ± 4.8 and +2.9 ± 4.9%) and TPU (+0.9 ± 5.9 and +0.9 ± 5.3%) compared to CON at LS and HS, respectively. Braking force was decreased by 3.4±9.1%at LS and by 2.7 ± 9.8% at HS for EVA compared to CON (P = 0.03, ! 2 = 0.20). TPU increased propulsive loading rate by 20.2 ± 24 and 16.4 ± 23.1% for LS and HS, respectively compared to CON (P = 0.01, ! 2 = 0.25). Both arch height (P = 0.06, ! 2 = 0.19) and medio-lateral control (P = 0.06, ! 2 = 0.16) showed a trend toward improved comfort for EVA and TPU vs. CON. Compared to shoes only, mainly EVA tended to improve RE and comfort at submaximal running speeds. Specific CFO-related running mechanical adjustments included a reduced braking impulse occurring in the first 25% of contact time with EVA, whereas wearing TPU increased propulsive loading rate.This project was conducted using an instrumented treadmill that was funded by QNRF (NPRP 4-760-3-217).https://doi.org/10.3389/fspor.2019.000341pubpu

Newly Standing Infants Increase Postural Stability When Performing a Supra-Postural Task.

Independent stance is one of the most difficult motor milestones to achieve. Newly standing infants exhibit exaggerated body movements and can only stand for a brief amount of time. Given the difficult nature of bipedal stance, these unstable characteristics are slow to improve. However, we demonstrate that infants can increase their stability when engaged in a standing goal-directed task. Infants\u27 balance was measured while standing and while standing and holding a visually attractive toy. When holding the toy, infants stood for a longer period of time, exhibited less body sway, and more mature postural dynamics. These results demonstrate that even with limited standing experience, infants can stabilize posture to facilitate performance of a concurrent task

RELlABlLlTY AND VALIDATION OF AN INERTIAL SENSOR USED TO MEASURE ORIENTATION ANGLE

This study examined the reliability and validity of an inertial measurement unit (IMU) for measuring orientation angle. An IMU was mounted onto a goniometer and moved through 0-90' with data collected at 10' increments. The process was repeated 10 times for all 3 axes. Reliability was measured via a typical error (TE) analysis from the 10 repeated trials. Validity was determined via a Pearson correlation and an ordinary least products (OLP) regression. The lMU was very reliable for all 3 axes (TE: x=0.03", y=0.03", z=0.02").T he Pearson correlation between the IMU and goniometer was large and significant for all 3 axes (r = 1.00,95%CI = 1 .O-1.0). The OLP regression showed no proportional bias for the 3 axes and only small fixed blas for the x and z axes. Overall the IMU tested was very reliably and accurate at measuring orientation angle