Browsing by Person "Girard, Olivier"

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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 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 custom foot orthoses and sex on mechanical asymmetries during treadmill running
(Taylor & Francis, 2025-10-07) Van Alsenoy, Ken; Santos, Derek; van der Linden, Marietta; Ryu, Joong Hyun; Al Raisi, Lubna; Girard, Olivier
We investigated the influence of custom foot orthoses and sex on mechanical asymmetries during treadmill running. Eighteen injury-free trained individuals (9 females) ran on an instrumented treadmill for six minutes at a speed 10% below their first ventilatory threshold (average: 9.9±1.3 km/h) under four footwear conditions: original shoe liner (control), two custom orthotics (one EVA, one TPU), and a hybrid (EVA heel, TPU forefoot). Vertical and antero-posterior ground reaction forces were recorded after ~5 minutes of running, encompassing 40 steps. Mechanical asymmetry was assessed using the ‘symmetry angle’ (SA) score. There were no significant main effects for condition (all P≥0.302) or sex (P≥0.137), and no significant condition × sex interactions for any variables (P≥0.063). Mean SA scores were less than 2% for contact time (0.39±0.23%), flight time (1.90±1.35%), step frequency (0.34±0.26%), peak vertical force (1.44±1.15%), and mean vertical loading rate (1.79±1.17%). Vertical and leg stiffness had mean SA scores of 3.11±1.73% and 1.86±1.00%, respectively. For braking (1.56±0.78%) and push-off (1.54±0.81%) phases and peak braking (2.94±1.61%) and push-off (2.33±1.17%) forces, mean SA scores ranged from ~1.5% to 3.0%. Overall, both male and female runners showed relatively even strides, and custom foot orthoses did not significantly alter natural stride asymmetries.
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.