Browsing by Person "Van Alsenoy, Ken K."

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Acute intense fatigue does not modify the effect of EVA and TPU custom foot orthoses on running mechanics, running economy and perceived comfort
(Springer, 2022-02-24) Van Alsenoy, Ken K.; Ryu, Joong Hyun; Girard, Olivier
We 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.
Constant low-to-moderate mechanical asymmetries during a treadmill graded exercise test
(Routledge, 2021-06-27) Girard, Olivier; Van Alsenoy, Ken K.; Li, Siu Nam; Ryu, Joong Hyun; Peeling, Peter
This study describes asymmetry in key mechanical variables during a treadmill-based, running graded exercise test (GXT). Twenty-one recreationally trained male runners completed a continuous, maximal GXT on an instrumented treadmill, starting at 9 km.h−1 with speed increases of +0.5 km.h−1 every 30 s, for the determination of ventilatory threshold (VT), respiratory compensation point (RCP), and maximal oxygen uptake (MAX). Ground reaction forces were recorded continuously and subsequently averaged from 10 consecutive steps corresponding to VT, RCP and MAX intensity stages (13.4 ± 1.2 km.h−1, 16.0 ± 1.6 km.h−1 and 18.2 ± 1.5 km.h−1, respectively). Asymmetry scores were assessed from the “symmetry angle” (SA) formulae, where a score of 0%/100% indicates perfect symmetry/asymmetry; these were then compared between the three intensity stages. There was no influence of exercise intensity on SA scores for any of the sixteen biomechanical variables (P > 0.222). The group mean SA scores did not exceed 1.5% for spatio-temporal variables (contact time, aerial time, frequency and step length). There were larger mean SA scores for mean loading rate (3.7 ± 2.7%) and most spring-mass model variables (vertical stiffness: 2.2 ± 1.6% and leg stiffness: 1.7 ± 1.4%). The SA scores were ∼1.0–3.5% for braking and propulsive phase durations, peak forces, and resulting impulses. Lower extremities behave similarly at submaximal and maximal intensities during GXT, indicating that runners maintained relatively even strides as intensity increased. However, practitioners must be careful not to infer the presence of asymmetry during GXT based on a single variable, given the lower SA scores for spatio-temporal parameters.
Custom foot orthoses improve performance, but do not modify the biomechanical manifestation of fatigue, during repeated treadmill sprints
(Springer, 2020-06-30) Girard, Olivier; Morin, Jean-Benoit; Ryu, Joong Hyun; Van Alsenoy, Ken K.; Funder: Qatar National Research Fund; Grant(s): NPRP 4 - 760 - 3 - 217
We 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.
Detecting mechanical breakpoints during treadmill-based graded exercise test: Relationships to ventilatory thresholds
(Routledge, 2021-09-15) Li, Siu Nam; Peeling, Peter; Hansen, Clint; Van Alsenoy, Ken K.; Ryu, Joong Hyun; Girard, Olivier
While changes in cardiorespiratory variables during graded exercise tests (GXTs) are well described, less is known about running mechanical alterations. We determined mechanical breakpoints during GXT and compared their temporal location with thresholds in ventilation. Thirty-one recreational male runners completed continuous GXT on an instrumented treadmill, starting at 2.5 m.s with velocity increases of + 0.14 m.s every 30 s. Subsequently, the first and second ventilatory thresholds (VT1 and VT2) were determined from expired gases. Spatio-temporal and antero-posterior force variables, and spring-mass model characteristics were averaged for each stage. Mechanical breakpoints were detected using a linear fit process that partitioned the timeseries into two regions and minimised the error sum of squares. All measurements were normalised to % GXT duration for subsequent comparisons. Fifteen out of 16 mechanical variables (all except leg stiffness) displayed breakpoints occurring between 61.9% and 82.3% of GXT duration; these occurred significantly later than VT1 (46.9 ± 6.4% of GXT duration, < 0.05). Mechanical breakpoints for eight variables (step frequency, aerial time, step length, peak push-off force, braking impulse, peak vertical force, maximal downward vertical displacement and leg compression) occurred at a time point not different to VT2 (75.3 ± 6.2% of GXT duration; all > 0.05). Relationships between mechanical breakpoints and either VT1 or VT2 were weak (all < 0.25). During treadmill GXT, breakpoints can be detected for the vast majority of mechanical variables (except leg stiffness), yet these are not related with ventilatory thresholds.
The effect of Custom Foot Orthotic Materials on Running Economy, Comfort, Running Mechanics, and Performance
(Queen Margaret University, Edinburgh, 2024-10) Van Alsenoy, Ken K.
Custom foot orthoses (CFOs) possess a unique surface geometry tailored to an individual’s foot, serving as an interface to redirect ground reaction forces. Their effect is defined by altering the orthotic shape in contact with the foot and choosing material characteristics to redirect or dampen these forces. In sports, CFOs have proven effective at mitigating injury risks and are part of a treatment plan for several lower limb and foot injuries. To date, empirical evidence for the impact of CFO materials on running and sprinting-related outcome measures is limited. The overarching aim of this PhD thesis wasto investigate the effect of CFO materials on running mechanics (kinetics and kinematics), running economy (RE), sprint performance, footwear comfort, and fatigue perception in uninjured recreational runners. It comprises one systematic review and meta-analysis, and two double-blinded randomised controlled crossover studies, resulting in five peer-reviewed publications. In the systematic review (article 1), with a meta-analysis of four studies (three weak and one moderate quality) revealed that oxygen consumption during submaximal running is reduced in the most comfortable footwear condition compared with the least comfortable footwear (MD: -2.06 mL.kg−1 .min−1 ; 95%CI: - 3.71, -0.42; P = 0.01). This finding underscored the importance of measuring footwear comfort along other variables such as running mechanics and RE. Article two compared EVA and TPU CFOs on RE, running mechanics and comfort at two different running speeds. CFOs had no statistically significant effect on RE, irrespective of materials or running speed. Peak braking force reduced with EVA by ∼4% compared to CON (P = 0.027). Propulsive loading rate increased with TPU ∼18% compared to CON (P = 0.009). Footwear comfort remained consistent across all conditions. Although these results were associated with moderately low submaximal running speeds in a rested state, examining the effects of CFOs on similar outcome measures when runners are fatigued or engaged in higher intensity exercises like sprinting appeared justified. Article three and four explored fatigue perception after repeated sprint exercises and constant velocity running, respectively. In Article three, both EVA and TPU increased sprint distance by respectively ∼0.6m (P = 0.004) and ∼0.4m (P = 0.018), without altering fatigue-induced mechanical changes. Article fourfound no significant differences in outcome measures between fatigued and fresh conditions, except for a reduction in loading rate (P = 0.046), increased minute ventilation (P = 0.020) and increased breathing frequency (P = 0.019). Further research focused on a hybrid (HYB) CFO, combining EVA in the heel and TPU in the forefoot. Article five showed reduced peak frontal plane angles (ankle eversion: P < 0.001,  2 = 0.72) and angular velocities (ankle eversion: P < 0.001,  2 = 0.64; ankle inversion: P < 0.001,  2 = 0.60) between conditions. Statistical non-parametric mapping revealed that HYB resulted in the largest proportions of significant changes during stance, when compared to control. In conclusion, the studies in this PhD thesis enhances the understanding of EVA, TPU and HYB CFOs in healthy recreational runners. For athletes, the findings could potentially expand the scope of foot orthoses use during sport activity, since it is not affecting RE. The small yet significant changes in running mechanics that were associated with material choice, could help guide clinicians in CFO prescription, whether using single materials or in combination.
The effect of EVA and TPU custom foot orthoses on running economy, running mechanics, and comfort
(Frontiers Media, 2019-09-19) Van Alsenoy, Ken K.; Ryu, Joong Hyun; Girard, Olivier; Hamlin, Michael John
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.
Effects of hybrid custom foot orthoses on running economy, running mechanics and comfort: a double-blinded randomized crossover study
(Elsevier, 2025-02-01) Van Alsenoy, Ken K.; van der Linden, Marietta; Santos, Derek; Girard, Olivier
Objective: This study examined the effects of orthotic materials on running economy, running mechanics, and footwear comfort. Design: A double-blinded randomized crossover study design was used. Method: Eighteen athletes ran on an instrumented treadmill for six minutes at speeds corresponding to 10% below their first ventilatory threshold (average: 9.9 ± 1.3 km/h) in four footwear conditions [control (CON), Ethyl vinyl acetate (EVA), Thermoplastic Polyurethane (TPU), and a combination of EVA and TPU (HYB)]. Results: No differences were found in running economy between conditions (p=0.099). All custom foot orthoses materials reduced peak heel impact force vs CON (p<0.001). TPU reduced hysteresis at heel impact vs CON (-47.8%, p=0.016). Shorter flight time (-3.8%, p=0.016; -3.1%, p=0.021) and lower mean vertical loading rate (-4.0%, p=0.003; -7.1%, p<0.001) occurred for HYB vs TPU and CON, respectively. Higher peak vertical loading rates (+7.4%, p=0.002) and earlier impact peaks (-5.7%, p<0.001) were found for HYB vs TPU. HYB exhibited longer propulsive phase duration (+2.0%, p=0.003) but lower peak propulsive force (-3.3%, p=0.009) vs CON. Reduced ‘overall comfort’ (-26.4%, p=0.004), ‘comfort of heel cushioning’ (-43.3%, p<0.001), and ‘comfort of forefoot cushioning’ (-18.3%, p=0.048) was found for HYB vs TPU, but ‘comfort of forefoot cushioning’ (+48.0%, p=0.032) showed an increase vs EVA. Conclusions: Combining materials could enhance comfort during running causing subtle changes in running mechanics. Overall, neither EVA, TPU nor their combination significantly improved running economy compared to CON.
Effects of Hybrid Custom Foot Orthoses on Running Economy, Running Mechanics and Comfort: A Double-Blinded Randomized Crossover Study
(Elsevier, 2024-10-23) Van Alsenoy, Ken K.; van der Linden, Marietta; Girard, Olivier; Ryu, Joong; Al Raisi, Lubna; Santos, Derek
Objective: This study examined the effects of orthotic materials on running economy (RE), running mechanics, and footwear comfort. Design: A double-blinded randomized crossover study design was used. Method: Eighteen athletes ran on an instrumented treadmill for six minutes at speeds corresponding to 10% below their first ventilatory threshold (average: 9.9 ± 1.3 km/h) in four footwear conditions [control (CON), Ethyl vinyl acetate (EVA), Thermoplastic Polyurethane (TPU), and a combination of EVA and TPU (HYB)]. Results: No differences were found in RE between conditions (p=0.099). All CFO materials reduced peak heel impact force vs CON (p<0.001). TPU reduced hysteresis at heel impact vs CON (-47.8%, p=0.016). Shorter flight time (-3.8%, p=0.016; -3.1%, p=0.021) and lower mean vertical loading rate (-4.0%, p=0.003; -7.1%, p<0.001) occurred for HYB vs TPU and CON, respectively. Higher peak vertical loading rates (+7.4%, p=0.002) and earlier impact peaks (-5.7%, p<0.001) were found for HYB vs TPU. HYB exhibited longer propulsive phase duration (+2.0%, p=0.003) but lower peak propulsive force (-3.3%, p=0.009) vs CON. Reduced ‘overall comfort’ (-26.4%, p=0.004), ‘comfort of heel cushioning’ (-43.3%, p<0.001), and ‘comfort of forefoot cushioning’ (-18.3%, p=0.048) was found for HYB vs TPU, but ‘comfort of forefoot cushioning’ (+48.0%, p=0.032) showed an increase vs EVA. Conclusions: Combining materials could enhance comfort during running causing subtle changes in running mechanics. Overall, neither EVA, TPU nor their combination significantly improved RE compared to CON.
Increased footwear comfort is associated with improved running economy – a systematic review and meta-analysis
(Routledge, 2021-11-21) Van Alsenoy, Ken K.; van der Linden, Marietta; Girard, Olivier; Santos, Derek
Footwear with or without custom foot orthotics have the potential to improve comfort, but the link with running performance needs further investigation. We systematically reviewed the association of footwear comfort on running economy in recreational runners. Nine electronic databases were searched from inception to March 2020. Eligible studies investigated both direct outcome measures of running performance (e.g. running speed) and/or physiological measures (e.g. running economy (RE)) alongside comfort for each footwear condition tested. Methodological quality was assessed using the ‘Effective Public Health Practice Project’ (EPHPP). RE during submaximal running was the most common physiological outcome reported in 4 of the 6 eligible studies. The absolute difference in RE between the most and least comfortable footwear condition was computed, and meta-analysis was conducted using a random effect model. The most comfortable footwear is associated with a reduction in oxygen consumption (MD: -2.06 mL.kg−1.min−1, 95%CI: -3.71, -0.42, P = 0.01) while running at a set submaximal speed. There was no significant heterogeneity (I2=0%, P=0.82). EPHPP quality assessment demonstrated weak quality of the studies, due to reporting bias and failing to disclose the psychometric properties of the outcome measures. It can be concluded with moderate certainty that improved RE in recreational athletes is associated with wearing more comfortable footwear compared to less comfortable footwear.
Isolated and combined effects of EVA and TPU custom foot orthoses on constant speed, treadmill running kinematics
(Frontiers Media, 2023-07-07) Van Alsenoy, Ken K.; van der Linden, Marietta; Girard, Olivier; Al Raisi, Lubna; Ryu, Joong Hyun; Santos, Derek
We investigated the isolated and combined (HYB) effects of ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) custom foot orthoses (CFO), compared to a control condition (CON; shoes only), on constant speed, treadmill running kinematics. Twenty (10 male) well-trained runners performed four, 6-min bouts at the same individualized speed for each bout on a treadmill under four footwear conditions (EVA, TPU, HYB and CON). Twenty markers and four clusters (four markers each) were placed on lower limbs and pelvis. Lower limbs and pelvis movements were tracked using a threedimensional motion capture system with 11 cameras (Vicon MX system, Oxford, UK). Lower limb joint angles and angular velocity were normalized to 100% of the stance phase. Peak ankle eversion (P < 0.001,  2 = 0.72), peak ankle eversion angular velocity (AV) (P < 0.001,  2 = 0.64), peak ankle inversion AV (P < 0.001,  2 = 0.60), and peak ankle internal rotation AV (P < 0.001,  2 = 0.49) demonstrated the largest differences between conditions. Statistical non-parametric mapping analysis revealed that HYB exhibited the largest proportions of change during the total stance phase compared to CON. All CFO materials caused significant reductions in peak angles and peak AVs at the ankle in the frontal plane, with more pronounced effects for harder (EVA) than softer (TPU) materials. These significant reductions occurred during large portions of the total stance phase for the angles and for AVs. While some effects could be found in more proximal joints such as knee and hip, most significant effects were found at the ankle joint. Overall, combining hard EVA material in the heel and soft TPU in the forefoot (HYB) resulted in significant, more favorable changes compared to CON, that lasted for the largest proportion of stance phase when compared to wearing shoes only.
No Effect of EVA and TPU Custom Foot Orthoses on Mechanical Asymmetries during Acute Intense Fatigue
(MDPI AG, 2023-03-11) Van Alsenoy, Ken K.; Ryu, Joong Hyun; Girard, Olivier
This 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.
The subtalar joint axis palpation technique part 2: Reliability and validity results using cadaver feet
(2014-07) Van Alsenoy, Ken K.; D'Aot, Kristiaan; Vereecke, Evie E.; De Schepper, Joris; Santos, Derek
Background: Clinically locating the point of no rotation to determine the subtalar joint axis location by applying pressure on the plantar surface of the foot was described by Kirby in 1987 but was never validated. We sought to extend a previously validated mechanical model to cadaver feet and to examine the intratester and intertester reliability. Methods: Four testers with different levels of experience determined the subtalar joint axis location and moved the subtalar joint through its range of motion, capturing the movement using kinematic analysis. The comparison of the spatial subtalar joint axis location as determined by palpation between and within testers determined the intertester and intratester reliability. The helical axis method was performed to validate the model. Results: The intrarater reliability varied from a high of = 0.96 to a low of = 0.26 for the slope and was, in general, high ( = 0.78-0.95) for the intersection. The interrater reliability scored moderate to high, depending on the specific cadaver specimen. Concerning the exact location of the subtalar joint axis, no significant difference was found between the results determined by different testers and the helical axis method. Conclusions: The palpation technique as part of the subtalar joint axis location and rotational equilibrium theory proposed by Kirby is a reliable and valid clinical tool. Experience in performing the palpation technique has a positive influence on the accuracy of the results. In the context of evidence-based practice, this technique could be a standard tool in the examination of patients with lower-limb-related pathologic disorders.
The Subtalar Joint Axis Palpation Technique-Part 1
(2014-05) Van Alsenoy, Ken K.; De Schepper, Joris; Santos, Derek; Vereecke, Evie E.; D'Aot, Kristiaan
Background: Locating the position of the subtalar joint axis can be a predictive clinical variable in biomechanical analysis and a valuable tool in the design of functional foot orthoses. Before testing Kirby's palpation technique to locate the subtalar joint axis in cadavers, it was important to develop and test the experimental methods in a mechanical model in which the exact location of the hinge joint can be controlled. Methods: Four testers determined the hinge joint location and moved it through its range of motion, capturing the movement of the joint axis using a kinematic model. The joint axis location was determined and validated by comparing the actual hinge joint location on the mechanical model with the location determined by the palpation technique described by Kirby in 1987 and the location determined by the helical joint axis method using three-dimensional kinematic data. Results: The overall angles result in mean slopes and intersections of 87 and 92 mm, 86 and 97 mm, 85 and 92 mm, and 88 and 91 mm for testers 1, 2, 3, and 4, respectively. Testers 1 and 3 were able to determine the location to 1 and 1 mm accuracy, tester 2 to 0 and 4 mm, and tester 4 to 2 and 2 mm compared with the kinematic data. Conclusions: The technique of determining the points of no rotation as described by Kirby could be validated by using a three-dimensional kinematic model to determine the helical axis.