Overground Running Research Articles

Running Gait Complexity During an Overground, Mass-Participation Five-Kilometre Run

Human locomotion contains innate variability which may provide health insights. Detrended fluctuation analysis (DFA) has been used to quantify the temporal structure of variability for treadmill running, although it has been less commonly applied to uncontrolled overground running. This study aimed to determine how running gait complexity changes in response to gradient and elapsed exercise duration during uncontrolled overground running. Sixty-eight participants completed an overground, mass-participation five-kilometre run (a parkrun). Stride times were recorded using an inertial measurement unit mounted on the distal shank. Data were divided into four consecutive intervals (uphill lap 1, downhill lap 1, uphill lap 2, downhill lap 2). The magnitude (SD) and structure (DFA) of stride time variability were compared across elapsed exercise duration and gradient using a repeated-measures ANOVA. Participants maintained consistent stride times throughout the run. Stride time DFA-α displayed a moderate decrease (d = |0.39| ± 0.13) during downhill running compared to uphill running. DFA-α did not change in response to elapsed exercise duration, although a greater stride time SD was found during the first section of lap 1 (d = |0.30| ± 0.12). These findings suggest that inter- and intra-run changes in gait complexity should be interpreted in the context of course elevation profiles before conclusions on human health are drawn.

Ankle Taping Does Not Affect Running Kinematics During a Treadmill Protocol in Well-Trained Runners: A Secondary Analysis from a Randomized Cross-Over Controlled Trial

Background: The purpose of this randomized cross-over controlled trial was to evaluate the biomechanical effects of ankle taping using rigid tape (RT) or kinesiotape (KT) compared to no taping during treadmill running in well-trained amateur runners. Methods: A total of 22 participants (15 men and 7 women) completed three running sessions on a treadmill, each lasting 30 min, under different conditions: no taping (CG), RT, and KT. Sagittal and frontal plane kinematics were analyzed using the Kinovea software to assess the ankle dorsiflexion, knee flexion, hip extension, tibial angle, foot strike pattern, heel eversion, and pelvic drop across three intervals (0–10, 10–20, and 20–30 min). Results: The results demonstrated no significant differences in sagittal plane variables (ankle dorsiflexion, knee flexion, hip extension, and cadence) or frontal plane variables (heel eversion and pelvic drop) between the CG, RT and KT groups at any time point. Although heel eversion significantly increased over time due to fatigue, the taping conditions did not affect running kinematics. Conclusions: These findings suggest that neither RT nor KT alters running biomechanics in well-trained runners over prolonged treadmill running. The study highlights that taping, commonly used to prevent ankle injuries, does not significantly modify lower limb kinematics in the absence of injury. Further research is needed to evaluate the effects of taping in novice or injured runners and under more demanding conditions, such as overground running.

The effect of femoral strapping on hip internal rotation and pain response in females with patellofemoral pain

BackgroundHip internal rotation has been reported to affect patellofemoral joint mechanics and contribute to patellofemoral pain (PFP). The SERF (Stability through External Rotation of the Femur) strap was designed to provide hip stability by pulling the thigh into external rotation during weight-bearing activities. Research questionWhat are the effects of the SERF strap on hip internal rotation and pain response in females with PFP who present with hip internal rotation during weight-bearing activities? MethodsNineteen females between the ages of 18 and 45 with a diagnosis of PFP participated. Lower extremity kinematics were obtained during three tasks (drop-jump, unilateral step-down, over-ground running) under strap and no-strap conditions. A 10-cm visual analog scale (VAS) was used to assess pain response during each task and strap condition. Participants who exhibited at least 5 degrees of hip internal rotation during at least one of the 3 tasks were included in the final analysis. Peak hip internal rotation and mean VAS score were compared separately between strap conditions across tasks using 2 ×3 (strap condition x task) repeated-measures ANOVAs. ResultsEighteen of the 19 females with PFP met the criteria for the presence of hip internal rotation. There was a significant reduction in peak hip internal rotation across tasks when wearing the SERF strap (mean ± sd = 7.4 ± 2.3, p<0.001). Additionally, the change in mean VAS pain score was significantly lower across tasks when wearing the SERF strap (1.0 ± 1.0, p=0.03). SignificanceThe SERF strap was effective in reducing hip internal rotation and PFP during dynamic weight-bearing activities in symptomatic females. The SERF strap may be a useful treatment adjunct for persons with PFP who present with poor transverse plane control of the hip.

Running Economy Benefits Of Advanced Footwear Technology Are Similar For Treadmill And Overground Running

Running Economy Benefits Of Advanced Footwear Technology Are Similar For Treadmill And Overground Running

Validity and Test-Retest Reliability of Spatiotemporal Running Parameter Measurement Using Embedded Inertial Measurement Unit Insoles.

Running is the basis of many sports and has highly beneficial effects on health. To increase the understanding of running, DSPro® insoles were developed to collect running parameters during tasks. However, no validation has been carried out for running gait analysis. The aims of this study were to assess the test-retest reliability and criterion validity of running gait parameters from DSPro® insoles compared to a motion-capture system. Equipped with DSPro® insoles, a running gait analysis was performed on 30 healthy participants during overground and treadmill running using a motion-capture system. Using an intraclass correlation coefficient (ICC), the criterion validity and test-retest reliability of spatiotemporal parameters were calculated. The test-retest reliability shows moderate to excellent ICC values (ICC > 0.50) except for propulsion time during overground running at a fast speed with the motion-capture system. The criterion validity highlights a validation of running parameters regardless of speeds (ICC > 0.70). This present study validates the good criterion validity and test-retest reliability of DSPro® insoles for measuring spatiotemporal running gait parameters. Without the constraints of a 3D motion-capture system, such insoles seem to be helpful and relevant for improving the care management of active patients or following running performance in sports contexts.

Consistency of sex-based differences between treadmill and overground running using an inertial measurement unit (IMU)

Differences in running gait between treadmill and overground running has been subject of study, while consistency of group differences between running surfaces has not been previously analysed. This study examined both the differences between running surfaces and the consistency of sex-based differences between surfaces in some spatiotemporal and kinematic variables measured by an inertial measurement unit fastened over the lumbar spine. Thirty-two (sixteen females) endurance runners firstly performed overground and then treadmill (1 % inclination) runs at speeds between 9–21 km∙h−1. Males showed lower flight time (FT) [moderate effect size (ES)] during treadmill running compared to overground, while females showed greater stride frequency (SF) (moderate ES), lower stride length (SL) (moderate ES), FT (moderate ES), and vertical (VT) trunk displacement (moderate ES), as well as greater medio-lateral (ML) trunk displacement (moderate ES). No differences in CT between surfaces were found (trivial to small). Furthermore, all the sex-differences were consistent between treadmill and overground running: Males showed lower SF (large and moderate ES, respectively), greater SL (large and moderate ES) and CT (moderate and large ES), lower FT (large ES), greater VT displacement (moderate to large ES), and lower ML displacement (moderate ES) than females. These results may be of interest to carefully transfer the running gait analyses between surfaces depending on sex.

Role of midsole hollow structure in energy storage and return in running shoes

Understanding the relationship between footwear features and their potential influence on running performance can inform the ongoing innovation of running footwear, aimed at pushing the limits of humans. A notable shoe feature is hollow structures, where an empty space is created in the midsole. Presently, the potential biomechanical effect of the hollow structures on running performance remains unknown. We investigated the role of hollow structures through quantifying the magnitude and timing of foot and footwear work. Sixteen male rearfoot runners participated in an overground running study in three shoe conditions: (a) a shoe with a hollow structure in the forefoot midsole (FFHS), (b) the same shoe without any hollow structure (Filled-FFHS) and (c) a shoe with a hollow structure in the midfoot midsole (MFHS). Distal rearfoot power was used to quantify the net power generated by foot and footwear together. The magnitude and timing of distal rearfoot work and ankle joint work were compared across shoe conditions. The results indicated that MFHS can significantly (p = 0.024) delay distal rearfoot energy return (3.4 % of stance) when compared to Filled-FFHS. Additionally, FFHS had the greatest positive (0.425 J/kg) and negative (−0.383 J/kg) distal rearfoot work, and the smallest positive (0.503 J/kg) and negative (−0.477 J/kg) ankle joint work among the three conditions. This showed that the size and location of the midsole hollow structure can affect timing and magnitude of energy storage and return. The forefoot hollow shoe feature can effectively increase distal rearfoot work and reduce ankle joint work during running.

3D motion analysis dataset of healthy young adult volunteers walking and running on overground and treadmill

Used on clinical and sportive context, three-dimensional motion analysis is considered as the gold standard in the biomechanics field. The proposed dataset has been established on 30 asymptomatic young participants. Volunteers were asked to walk at slow, comfortable and fast speeds, and to run at comfortable and fast speeds on overground and treadmill using shoes. Three dimensional trajectories of 63 reflective markers, 3D ground reaction forces and moments were simultaneously recorded. A total of 4840 and 18159 gait cycles were measured for overground and treadmill walking, respectively. Additionally, 2931 and 18945 cycles were measured for overground and treadmill running, respectively. The dataset is presented in C3D and CSV files either in raw or pre-processed format. The aim of this dataset is to provide a complete set of data that will help for the gait characterization during clinical gait analysis and in a sportive context. This data could be used for the creation of a baseline database for clinical purposes to research activities exploring the gait and the run.

Effects of running-induced fatigue on joint kinematics and kinetics during overground running: a systematic review and meta-analysis.

This study evaluated the acute fatigue-inducing effect of distance running on kinematics and kinetics during overground running. Standardised mean differences (SMD) with 95% confidence intervals (95% CI) were used to pool data across 16 studies. Effects during consistent (pre- and post-fatigue running speed within ± 5%) versus varied speed running (difference of >5% between running speeds) were analysed separately. There was strong evidence that running-induced fatigue significantly increases ground contact times at consistent running speeds (SMD 0.52 [95% CI 0.22, 0.82]) and moderate evidence that step length shortens at varied running speeds (SMD -1.27 [95% CI -1.79, -0.75]). There was strong evidence that fatigue does not change peak: hip and knee flexion angles, hip adduction angle, hip and knee internal rotation angles, hip and knee extension moments, hip and knee abduction moments, knee abduction angle, knee flexion and extension moments, knee adduction moment, rearfoot eversion angle, and plantarflexion moments, or knee flexion and plantarflexion range of motion during stance. Running-induced fatigue increases contact times and reduces step length, whereas lower-body joint angles and moments are unchanged. Minimising changes in stride parameters could provide a mechanism for reducing the effects of fatigue on running performance.

Learning effects in over-ground running gait retraining: A six-month follow-up of a quasi-randomized controlled trial

ABSTRACT This study evaluated learning and recall effects following a feedback-based retraining program. A 6-month follow-up of a quasi-randomized controlled trial was performed with and without recall. Twenty runners were assigned to experimental or control groups and completed a 3-week running program. A body-worn system collected axial tibial acceleration and provided real-time feedback on peak tibial acceleration for six running sessions in an athletic training facility. The experimental group received music-based biofeedback in a faded feedback scheme. The controls received tempo-synchronized music as a placebo for blinding purposes. The peak tibial acceleration and vertical loading rate of the ground reaction force were determined in a lab at baseline and six months following the intervention to assess retention and recall. The impacts of the experimental group substantially decreased at follow-up following a simple verbal recall (i.e., run as at the end of the program): peak tibial acceleration:-32%, p = 0.018; vertical loading rate:-34%, p = 0.006. No statistically significant changes were found regarding the retention of the impact variables. The impact magnitudes did not change over time in the control group. The biofeedback-based intervention did not induce clear learning at follow-up, however, a substantial impact reduction was recallable through simple cueing in the absence of biofeedback.

Comparison of muscle activity of the lower limbs while running on different treadmill models.

Treadmill running is a common method of exercise and to study human locomotion. Research has examined the kinematics and kinetics of overground and treadmill running, but there has been less focus on the levels of muscle activity during treadmill running. We investigated if muscle activity is different while running overground compared to running on a variety of treadmills. A total of 11 healthy individuals ran at 3 speeds (2.6, 3.6, 4.5 m/s) under 4 different running conditions (3 treadmills, overground). The three treadmills included a typical home exercise treadmill, a midsize commercial research treadmill, and a large, instrumented research treadmill. Surface EMG of the tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF) and biceps femoris (BF) muscles were measured for each running condition. The integrated EMG was computed for each running condition for the stance and swing phase, as well as 100 ms before and after the heel-strike. Friedman analysis revealed significant effects during the stance phase for GM and RF at all speeds, such that muscle activation was lower on the treadmills relative to overground. During the stance phase at faster speeds, the muscle activity was higher for the TA and lower for the BF while running on the different treadmills compared to overground running. Before heel-strike, the TA was significantly less active during treadmill compared to overground running at 2.6 m/s and the RF showed significantly higher activity at 3.6 m/s and 4.5 m/s while running on the different treadmills. Summarizing, differences were mainly observed between the different treadmill conditions relative to overground running. Muscle activation differences between the different treadmill conditions were observed at faster running speeds for RF during the pre-heel-strike phase only. Different types of treadmills with different mechanical properties affects the muscle activity during stance phase as well as in preparation to heel-strike. Additionally, the muscle activity is greater during overground compared to treadmill running during the stance phase for the GM, BF, and RF.

Predicting overstriding with wearable IMUs during treadmill and overground running

Running injuries are prevalent, but their exact mechanisms remain unknown largely due to limited real-world biomechanical analysis. Reducing overstriding, the horizontal distance that the foot lands ahead of the body, may be relevant to reducing injury risk. Here, we leverage the geometric relationship between overstriding and lower extremity sagittal segment angles to demonstrate that wearable inertial measurement units (IMUs) can predict overstriding during treadmill and overground running in the laboratory. Ten recreational runners matched their strides to a metronome to systematically vary overstriding during constant-speed treadmill running and showed similar overstriding variation during comfortable-speed overground running. Linear mixed models were used to analyze repeated measures of overstriding and sagittal segment angles measured with motion capture and IMUs. Sagittal segment angles measured with IMUs explained 95% and 98% of the variance in overstriding during treadmill and overground running, respectively. We also found that sagittal segment angles measured with IMUs correlated with peak braking force and explained 88% and 80% of the variance during treadmill and overground running, respectively. This study highlights the potential for IMUs to provide insights into landing and loading patterns over time in real-world running environments, and motivates future research on feedback to modify form and prevent injury.

Ankle and hindfoot motion of healthy adults during running revealed by dynamic biplane radiography: Side-to-side symmetry, sex-specific differences, and comparison with walking

This study aimed to characterize ankle and hindfoot kinematics of healthy men and women during overground running using biplane radiography, and to compare these data to those previously obtained in the same cohort during overground walking. Participants ran across an elevated platform at a self-selected pace while synchronized biplane radiographs of their ankle and hindfoot were acquired. Motion of the tibia, talus, and calcaneus was tracked using a validated volumetric model-based tracking process. Tibiotalar and subtalar 6DOF kinematics were obtained. Absolute side-to-side differences in ROM and kinematics waveforms were calculated. Side-to-side and sex-specific differences were evaluated at 10 % increments of stance phase with mixed model analysis. Pearson correlation coefficients were used to assess the relationship between stance-phase running and walking kinematics. 20 participants comprised the study cohort (10 men, mean age 30.8 ± 6.3 years, mean BMI 24.1 ± 3.1). Average absolute side-to-side differences in running kinematics waveforms were 5.6°/2.0 mm or less at the tibiotalar joint and 5.2°/3.2 mm or less at the subtalar joint. No differences in running kinematics waveforms between sides or between men and women were detected. Correlations were stronger at the tibiotalar joint (42/66 [64 %] of correlations were p < 0.05), than at the tibiotalar joint (38/66 [58 %] of correlations were p < 0.05). These results provide a normative reference for evaluating native ankle and hindfoot kinematics which may be informative in surgical or rehabilitation contexts. Sex-specific differences in ankle kinematics during overground running are likely not clinically or etiologically significant. Associations seen between walking and running kinematics suggest one could be used to predict the other.

Knee Offloading by Patients During Walking and Running After Meniscectomy.

Changes in knee loading have been reported after meniscectomy. Knee loading has previously been assessed during jogging and treadmill running rather than overground running, which could give altered results. The purpose of this study was to evaluate knee function during overground running and walking after meniscectomy. It was hypothesized that the affected limb would demonstrate higher external knee adduction moment, lower knee flexion moment (KFM), and lower knee rotation moment (KRM) compared with the contralateral limb and with healthy individuals. Controlled laboratory study. Kinematic and kinetic data were collected during running and walking in individuals after a meniscectomy and healthy individuals. Total knee joint moments (TKJM) were calculated from the sagittal, frontal, and transverse knee moments. Isometric quadriceps strength, perceived knee function, and kinesiophobia were also assessed. A mixed linear model compared differences between the affected leg, the contralateral leg, and the healthy leg. Data were collected on 20 healthy individuals and 30 individuals after a meniscectomy (mean ± SD, 5.7 ± 2.9 months postsurgery), with 12, 16, and 2 individuals who had medial, lateral, and both medial and lateral meniscectomy, respectively. The affected limb demonstrated lower TKJM (P < .001), KFM (P = .004), and KRM (P < .001) during late stance of walking compared with the healthy group. Lower TKJM and KFM were observed during running in the affected limb compared with the contralateral limb and healthy group. No significant differences were observed between contralateral and healthy limbs except for KRM during late stance of walking. Lower quadriceps strength was observed in the affected (P < .001) and contralateral limbs (P = .001) compared with the healthy group. Individuals after a meniscectomy also reported greater kinesiophobia (P = .006) and lower perceived knee function (31.1%; P < .001) compared with the healthy group. After meniscectomy, individuals who sustained a traumatic meniscal injury showed lower TKJM in the affected limb compared with the contralateral limb and healthy individuals. This decrease in TKJM can be attributed to altered knee-loading strategies in the sagittal and transverse planes. Improving movement strategies, quadriceps strength, and kinesiophobia through rehabilitation approaches will allow individuals to load their knee appropriately when returning to sport. NCT03379415 (ClinicalTrials.gov identifier).

Should a 1% gradient be used to equate the metabolic cost between treadmill and overground running?

Introduction&#x0D; Running on a motorized treadmill offers the possibility of precise adjustments in speed as well as more complex monitoring of athletes. On the other hand, the lack of wind resistance compared with outdoor running introduces a possible significant deviation from the expected metabolic cost of running at higher speeds. The literature offers contrasting views on the topic, with older studies suggesting a lower metabolic cost for treadmill running and vice-versa for newer investigations. Nonetheless, a recommendation that treadmills use a 1% inclination gradient to account for the lack of wind resistance remains very influential in the field. We therefore investigated whether cardiorespiratory responses differ between running on a motorized treadmill with a 1% incline compared with running outdoors on a running track at a similar speed.&#x0D; Methods&#x0D; Fourteen highly trained male athletes (age 28 ± 5 years, height 180 ± 6 cm, body mass 70 ± 6 kg and peak oxygen consumption, V̇O2peak, 64 ± 4 mL kg-1･min-1) visited the laboratory on three different occasions, separated at least by 72 h. On the first day, participants performed an incremental running test to determine V̇O2peak and to familiarize themselves with the laboratory settings and equipment. On each of the two subsequent testing days, participants performed, after standardized warm-up, a 5-min run at 14 km･h-1 on either the treadmill (Pulsar It 3P, H/P Cosmos, Germany) or the track, in randomized order. Feedback regarding pacing on the track was given every 200 m. Gas exchange and heart rate were monitored throughout the runs using a portable metabolic cart (Metamax 3B, Cortex, Germany) and a connected heart rate monitor (Polar H10, Polar, Finland). In both conditions, the metabolic cart was carried by the participants using a vest provided by the manufacturer. Comparisons between conditions were performed using paired t-tests. A separate group of 4 individuals performed a set of two runs on the treadmill at 14 km･h-1 (in balanced order), once with 1% incline and once with 0% incline, to investigate the effect of the gradient on V̇O2.&#x0D; Results&#x0D; The results revealed a significant increase in the cardiorespiratory response on the treadmill compared with the track for V̇O2 (+12.6 ± 5.5%, p &lt; 0.001, Dz = 2.6), heart rate (+5.5 ± 3.7%, p &lt; 0.001, Dz = 1.5), and minute ventilation (+15.0 ± 0.1%, p &lt; 0.001, Dz = 2.6). Data from the additional four participants showed that a 1% gradient increased V̇O2 by 4.4 ± 2.4% (p = 0.026) compared with a 0% gradient.&#x0D; Discussion/Conclusion&#x0D; This study shows that running on this particular treadmill model induces significantly higher cardiorespiratory responses compared with outdoor running, and that setting the incline to 1% significantly adds to this difference, instead of dampening it. These findings challenge the widely held assumption that treadmills should be set at 1% incline to yield equivalent cardiorespiratory responses to overground running. Each laboratory should test their unique settings to ascertain whether corrections based on incline are necessary.

Impact of midsole thickness on physiological responses during running in well-trained athletes

Introduction Modern running shoes have revolutionized long-distance performances by decreasing the amount of oxygen athletes need when running at a given speed, which is termed running economy. In 2022, World Athletics imposed an upper limit of 40 mm for midsole thickness, possibly to prevent shoes from having an overemphasized role in performance. This ceiling, however, seems arbitrary, and a better understanding of whether midsole thickness affects running economy is needed. This study therefore investigated if midsole thickness affects oxygen consumption both indoors and outdoors, as early findings from treadmill studies may not translate to overground running. Methods Following a familiarization trial including an incremental test, 16 well-trained male runners (weight 70 ± 6 kg, age 28 ± 5 years, peak oxygen uptake, V̇O2peak 64 ± 4 ml O2･kg-1･min-1, peak running speed 20.0 ± 0.8 km･h-1) completed two testing visits, once on a treadmill and once on a track, each consisting of twelve 5-min runs at submaximal speed (16 km･h-1) alternating three different footwear conditions: an entry-level running shoe (EL, 30 mm midsole thickness) and two carbon-plated modern running shoes with midsole thickness of 40 and 50 mm, respectively. The shoe order was randomized and balanced between each of the four replicates. Gas exchange and heart rate were continuously measured throughout the runs. Results Running with 40 mm shoes reduced V̇O2 compared with EL shoes by 2.4 ± 1.1% on the treadmill and 4.0 ± 1.2% when running overground (both p &lt; 0.001). Running with 50mm shoes also decreased V̇O2 compared with EL shoes both on the treadmill (-2.7 ± 1.6%, p &lt; 0.001) and overground (-4.6 ± 1.8%, p &lt; 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3 ± 1.3%, p = 0.586; overground: +0.6 ± 1.4%, p = 0.189). Similarly, heart rate was lower compared with the EL shoes in both the 40 mm shoes (treadmill -1.3 ± 0.6%; overground -2.0 ± 0.6%; both p &lt; 0.001) and 50 mm shoes (treadmill -1.6 ± 0.7%; overground -2.3 ± 0.6%, both p &lt; 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3% ± 0.6%, p = 0.106; overground: +0.4 ± 0.6%, p = 0.090). Interestingly when running overground V̇O2 decreased over time for the 50 mm shoes, reaching significance between replicates 1 and 4 (p = 0.017), which was not the case for the 40 mm shoes (p = 0.817). The V̇O2 ratio between the 50 mm and 40 mm shoes was 1.003 in replicate 1 and 0.987 in replicate 4 (p = 0.108). Discussion/Conclusion Our data suggests that a 50 mm midsole does not offer significant benefits compared with race-legal 40 mm midsole shoes when tested over short durations. The 50 mm shoes cause a noticeable decrease in V̇O2 over time when used outdoors, which may reflect a learning effect to this unfamiliar midsole thickness. Longer test sessions may be necessary to reveal the actual impact on running economy of shoes with over 40 mm midsoles.

Curved non-motorized treadmills do not biomechanically replicate overground running better than motorized treadmills

ABSTRACT The purpose of this study was to determine if curved non-motorized treadmills can reproduce overground running better than motorized treadmills by analysing the differences in joint kinematics (hip, knee, and ankle) using SPM. Nineteen recreational runners completed three randomized running tests on these surfaces. Kinematic data from the hip, knee, and ankle joints were collected. Two-tailed SPM t-tests were performed to analyse time-continuous gait cycles in three anatomical planes of each joint. Higher within-subject variability was observed in the frontal and transverse planes during curved non-motorized treadmill running. SPM analysis showed more significant differences (p < 0.05) between curved non-motorized treadmill and overground than between motorized treadmill and overground, mainly in knee (from 12% to 30% and 93% to 99% of the gait cycle) and ankle (from 19% to 23% of the gait cycle) in the sagittal plane. Therefore, running on curved non-motorized treadmills is more biomechanically different compared to overground than motorized treadmills, and might not be the best strategy to replicate overground running in terms of joint kinematics during highly controlled research studies. However, they could be an interesting tool in rehabilitation or training environments since the changes observed in joint kinematics were likely not functionally relevant.

Four Sessions of Repeated-Sprint Cycling Training With or Without Severe Hypoxia Do Not Modify Overground Running Sprint Force-Velocity Profile.

To investigate the effect of cycling-based repeated-sprint training in hypoxia versus in normoxia on single overground running sprint performance and associated force-velocity (F-V) profile in world-class female rugby sevens players. Eighteen world-class female rugby sevens players were randomly assigned to repeated-sprint cycling training in normobaric hypoxia (n = 9) or normoxia (n = 9) groups. Training consisted of 4 sessions ofrepeated-sprint cycling training in normobaric hypoxiaor in normoxia (4 × 5 × 5-s cycle sprints-25-s intersprint recovery performed in simulated altitude of ∼5000m or in normoxia with 3-min interset rest in normoxia for both groups) in addition to rugby sevens training and strength and conditioning sessions within a 9-day intervention period before an international competition. Before and 1day after the intervention, single 50-m overground running "all-out" sprint performance and associated F-V-related mechanical output were assessed. No interaction (group × time; all P > .088), time effect(before vs 1d after; all P > .296), or group effect(repeated-sprint cycling training in normobaric hypoxia vs in normoxia; all P > .325) was detected for 50-m overground running sprint performance and any derived F-V profiling variables. Four sessions ofrepeated-sprint training either in hypoxia or in normoxia performed over 9days had no influence on single 50-m overground running sprint performance and associated F-V profile. In world-class female rugby sevens players, the intervention (training camp before an international competition) might have been too short to induce measurable changes. It is also plausible that implementing a similar program in players with likely different F-V profile may result in negligible mechanical effect.

Gender differences on the age-related distal-to-proximal shift in joint kinetics during running.

The increased running participation in women and men over 40 years has contributed to scientific interest on the age-related and gender differences in running performance and biomechanics over the last decade. Gender differences in running biomechanics have been studied extensively in young runners, with inconsistent results. Understanding how gender influences the age-related differences in running mechanics could help develop population-specific training interventions or footwear to address any potential different mechanical demands. The purpose of this study was to assess gender and age effects on lower limb joint mechanics while running. Middle-aged men (57 ± 5 years) and women (57 ± 8 years) and young men (28 ± 6 years) and women (30 ± 6 years) completed five overground running trials at a set speed of 2.7 m/s while lower limb kinematics and ground reaction forces were collected. Lower limb joint kinetics were computed, normalized to body mass and compared between age and gender groups using two-factor analyses of variance. Women reported slower average running paces than men and middle-aged runners reported slower running paces than young runners. We confirmed that young runners run with more ankle, but less hip positive work and peak positive power compared to middle-aged runners (i.e., age-related distal-to-proximal shift in joint kinetics). We also present a novel finding that women run with more ankle, but less hip peak positive power compared to men suggesting an ankle dominant strategy in women at a preferred and comfortable running pace. However, the age-related distal-to-proximal shift in joint kinetics was not different between genders.

Exploring running styles in the field through cadence and duty factor modulation

According to the dual-axis model, running styles can be defined by cadence and duty factor, variables that have been associated with running performance, economy and injury risk. To guide runners in exploring different running styles, effective instructions to modulate cadence and duty factor are needed. Such instructions have been established for treadmill running, but not for overground running, during which speed can be varied. In this study, five participants completed eight field training sessions over a 4-week training period with acoustic instructions to modulate cadence, duty factor, and, in combination, running style. Instructions were provided via audio files. Running data were collected with sports watches. Participants’ experiences with guided-exploration training were evaluated with the user experience questionnaire. Data analysis revealed acoustic pacing and verbal instructions to be effective in respectively modulating cadence and duty factor, albeit with co-varying effects on speed and the non-targeted variable (i.e. duty factor or cadence). Combining acoustic pacing and verbal instructions mitigated these co-varying effects considerably, allowing for running-style modulations in intended directions (particularly towards the styles with increased cadence and increased duty factor). User experience of this form of guided-exploration training was overall positive, but could be improved in terms of autonomy (dependability). In conclusion, combining acoustic pacing and verbal instructions for running-style modulation is effective in overground running.