Effects of deceptive footwear condition on subjective comfort and running biomechanics

Comfort is a major criterion for footwear selection. Previous studies have suggested that physical properties were not enough to predict comfort and psychological factors could also affect the perception. To understand comfort, this study examined the effect of controlled shoe description and price cue on the perception of comfort. Furthermore, this study also examined the running biomechanics in response to footwear conditions of differing comfort. Fifteen runners completed treadmill running tests in two conditions: Shoe A and Shoe B. The same pair of neutral running shoes was used in both conditions, yet, Shoe B was described to be the “latest model designed to maximize comfort” and more expensive than Shoe A. Comfort assessment was conducted after the running trial of each condition. Participants reported significantly greater comfort in Shoe B than Shoe A (p=0.011, Cohen’s d=0.70). There were no significant differences found among the temporal-spatial parameters (p>0.916) and the vertical loading rates (p>0.161) when comparing the more and less comfortable conditions. In conclusion, runners exhibited a biased perception of footwear comfort when presented with different shoe description and price information. However, such a difference in perceived comfort alone is not likely to affect running biomechanics

Measurement agreement between a newly developed sensing insole and traditional laboratory-based method for footstrike pattern detection in runners

This study introduced a novel but simple method to continuously measure footstrike patterns in runners using inexpensive force sensors. Two force sensing resistors were firmly affixed at the heel and second toe of both insoles to collect the time signal of foot contact. A total of 109 healthy young adults (42 males and 67 females) were recruited in this study. They ran on an instrumented treadmill at 0˚, +10˚, and -10˚ inclinations and attempted rearfoot, midfoot, and forefoot landings using real time visual biofeedback. Intra-step strike index and onset time difference between two force sensors were measured and analyzed with univariate linear regression. We analyzed 25,655 footfalls and found that onset time difference between two sensors explained 80–84% of variation in the prediction model of strike index (R-squared = 0.799–0.836, p<0.001). However, the time windows to detect footstrike patterns on different surface inclinations were not consistent. These findings may allow laboratory-based gait retraining to be implemented in natural running environments to aid in both injury prevention and performance enhancement

Gait Retraining for the Reduction of Injury Occurrence in Novice Distance Runners: 1-Year Follow-up of a Randomized Controlled Trial

Background: The increasing popularity of distance running has been accompanied by an increase in running-related injuries, such that up to 85% of novice runners incur an injury in a given year. Previous studies have used a gait retraining program to successfully lower impact loading, which has been associated with many running ailments. However, softer footfalls may not necessarily prevent running injury. Purpose: To examine vertical loading rates before and after a gait retraining program and assess the effectiveness of the program in reducing the occurrence of running-related injury across a 12-month observation period. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 320 novice runners from the local running club completed this study. All the participants underwent a baseline running biomechanics evaluation on an instrumented treadmill with their usual running shoes at 8 and 12 km/h. Participants were then randomly assigned to either the gait retraining group or the control group. In the gait retraining group (n = 166), participants received 2 weeks of gait retraining with real-time visual feedback. In the control group (n = 154), participants received treadmill running exercise but without visual feedback on their performance. The training time was identical between the 2 groups. Participants’ running mechanics were reassessed after the training, and their 12-month posttraining injury profiles were tracked by use of an online surveillance platform. Results: A significant reduction was found in the vertical loading rates at both testing speeds in the gait retraining group (P 0.99), whereas the loading rates were either similar or slightly increased in the control group after training (P = .001 to 0.461, Cohen’s d = 0.03 to −0.14). At 12-month follow-up, the occurrence of running-related musculoskeletal injury was 16% and 38% in the gait retraining and control groups, respectively. The hazard ratio between gait retraining and control groups was 0.38 (95% CI, 0.25-0.59), indicating a 62% lower injury risk in gait-retrained runners compared with controls. Conclusion: A 2-week gait retraining program is effective in lowering impact loading in novice runners. More important, the occurrence of injury is 62% lower after 2 weeks of running gait modification. Registration: HKUCTR-1996 (University of Hong Kong Clinical Trials Registry)

Cyclists with patellofemoral pain do not demonstrate altered hip and knee kinematics

Background: Cycling is a popular sport but overuse injury, especially patellofemoral pain, is a very common musculoskeletal disorder among cyclists. Faulty kinematics at the hip and knee joints in runners with patellofemoral pain has been extensively investigated. Previous studies reported that a greater peak hip adduction, femoral internal rotation, knee adduction, and knee tibial internal rotation are associated with the development of patellofemoral pain in this cohort. Relatively, little work has been done to examine the relationship between patellofemoral pain and the lower extremities kinematics in cyclists. Purpose: This study examined the difference between the 3-dimensional kinematics on the coronal and transverse plane of the hip and knee joints between cyclists with and without patellofemoral pain. Methods: Fourteen cyclists participated in the study. Seven of them were patients with patellofemoral pain with proper diagnosis. Another seven cyclists were healthy characteristic-matched controls. During the experiment, all the subjects rode with their usual bike mounting on a trainer at standardized cadence, speed, and power. Motion analysis system was used to capture the three-dimensional movements of the affected lower limbs and the side-matched limbs in the experimental and control group respectively. Mann Whitney U tests were used to test the dependent variables between two groups. Results: In the coronal plane movement, no statistical significance was found in peak hip and knee adduction between the cyclists with and without PFP (p ranged from 0.259 to 0.456). In the transverse plane movement, we also failed to detect any difference in peak hip and knee internal rotation between two groups (p ranged from 0.259 to 0.966). Conclusion(s): Cyclists with patellofemoral pain did not demonstrate any kinematics difference at hip and knee joints when compared with healthy cyclists. Our findings indicated that the theory explaining the development of PFP during weight bearing exercises e.g. running, may not be applicable to cycling

Facilitatory and inhibitory effects of Kinesio tape : fact or fad?

Objectives: Kinesio tape (KT) is a commonly used intervention in sports. It claims to be able to alter the muscle activity, in terms of both facilitation and inhibition, by certain application methods. This study compared the neuromuscular activity of the wrist extensor muscles and maximal grip strength with facilitatory, inhibitory KT, and tapeless condition in healthy adults who were ignorant about KT. Potential placebo effects were eliminated by deception. Design: Randomized deceptive trial. Methods: 33 participants performed maximal grip assessment in a randomly assigned order of three taping conditions: true facilitatory KT, inhibitory KT, and no tape. The participants were blindfolded during the evaluation. Under the pretense of applying a series of adhesive muscle sensors, KT was applied to their wrist extensor muscles of the dominant forearm in the first two conditions. Within-subject comparisons of normalized root mean square of the wrist extensors electromyographic activity and maximal grip strength were conducted across three taping conditions. Results: 31 out of 33 enlisted participants were confirmed to be ignorant about KT. No significant differences were found in the maximum grip strength (p = 0.394), electromyographic activity (p = 0.276), and self-perceived performance (p = 0.825) between facilitatory KT, inhibitory KT, and tapeless conditions. Conclusions: Neither facilitatory nor inhibitory effects were observed between different application techniques of KT in healthy participants. Clinically, alternative method should be used for muscle activity modulation

Can runners maintain a newly learned gait pattern outside a laboratory environment following gait retraining?

Background: Previous peak tibial shock gait retraining programs, which were usually conducted on a treadmill, were reported to be effective on impact loading reduction in runners. However, whether the trained runners can translate the training effect at different running modes (treadmill/overground), or running slopes (uphill/ downhill), remains unknown. Research question: Is the training effect from a treadmill-based gait retraining translatable to unconstrained running conditions, including overground and uphill/downhill running? Methods: The peak tibial shock was measured during treadmill/overground running, as well as level/uphill/ downhill running before and after a course of treadmill-based gait retraining. The 8-session training aimed to soften footfalls using real-time biofeedback of tibial shock data. Repeated measures ANOVA was used to examine the effect of training, running mode, and running slope, on a group level. Reliable change index of each participant was used to assess the individual response to the training protocol used in this study. Results: Eighty percent of the participants were responsive to the gait retraining and managed to reduce their peak tibial shock following training. They managed to translate the training effect to treadmill slope running (Level: p < 0.05, Cohen’s d = 1.65; Uphill: p = 0.001, Cohen’s d = 0.91; Downhill: p < 0.05; Cohen’s d = 1.29) and overground level running (p = 0.014, Cohen’s d = 0.85). However, their peak tibial shock were not reduced during overground slope running (Uphill: p = 0.054; Cohen’s d = 0.62; Downhill p = 0.12; Cohen’s d = 0.48). Significance: Our findings indicated that a newly learned gait pattern may not fully translate to running outside of the laboratory environment

Transfer of the learning effect in outdoor conditions with varied surface inclinations upon completion of an indoor gait retraining program

Rational & Objective Running retraining using kinetic biofeedback (e.g., tibial shock) has been shown to be effective in impact loading control and injury prevention. Previous training program was usually conducted indoor to enable continuous feedback of peak tibial shock. However, it is not known if the training could benefit running in outdoor conditions across various surface inclinations (e.g., uphill or downhill). This study aimed to compare the reduction in peak tibial shock following running retraining during indoor and outdoor running across varying surface inclinations. Methods Fourteen runners underwent a running retraining program as described by Crowell and Davis in 2011. Before and after the program, participants were asked to perform indoor treadmill running and outdoor overground running at three inclination surfaces (level, 10% uphill and - 10% downhill). During all the six conditions, their peak acceleration from right distal tibia were measured using wireless accelerometers. Results The effect of training depended on running environment (F(1,13) = 11.179, p = 0.005) as well as surface inclinations (F(2,13) = 4.322, p = 0.024). During indoor running, participants managed to reduce the peak tibial shock during level and downhill running (p 0.137, Cohen’s d = 0.32-0.47). Conclusions The learning effect of the current running gait retraining program may not transfer to a reduced peak tibial shock during various inclination surfaces and outdoor running conditions

Bilateral Corticomotor Reorganization and Symptom Development in Response to Acute Unilateral Hamstring Pain: A Randomized, Controlled Study

Accumulating evidence demonstrates that pain induces adaptations in the corticomotor representations of affected muscles. However, previous work has primarily investigated the upper limb, with few studies examining corticomotor reorganization in response to lower limb pain. This is important to consider, given the significant functional, anatomical, and neurophysiological differences between upper and lower limb musculature. Previous work has also focused on unilateral corticomotor changes in response to muscle pain, despite an abundance of literature demonstrating that unilateral pain conditions are commonly associated with bilateral motor dysfunction. For the first time, this study investigated the effect of unilateral acute hamstring pain on bilateral corticomotor organization using transcranial magnetic stimulation (TMS) mapping. Corticomotor outcomes (TMS maps), pain, mechanical sensitivity (pressure pain thresholds), and function (maximal voluntary contractions) were recorded from 28 healthy participants at baseline. An injection of pain-inducing hypertonic (n = 14) or pain-free isotonic (n = 14) saline was then administered to the right hamstring muscle, and pain ratings were collected every 30 seconds until pain resolution. Follow-up measures were taken immediately following pain resolution and at 25, 50, and 75 minutes post-pain resolution. Unilateral acute hamstring pain induced bilateral symptom development and changes in corticomotor reorganization. Two patterns of reorganization were observed—corticomotor facilitation and corticomotor depression. Corticomotor facilitation was associated with increased mechanical sensitivity and decreased function bilaterally (all P < .05). These effects persisted for at least 75 minutes after pain resolution. Perspectives: These findings suggest that individual patterns of corticomotor reorganization may contribute to ongoing functional deficits of either limb following acute unilateral lower limb pain. Further research is required to assess these adaptations and the possible long-term implications for rehabilitation and reinjury risk in cohorts with acute hamstring injury.</p

Comparison of the correlations between impact loading rates and peak accelerations measured at two different body sites : intra- and inter-subject analysis

Background: High average (VALR) and instantaneous vertical loading rates (VILR) during impact have been associated with many running-related injuries. Peak acceleration (PA), measured with an accelerometer, has provided an alternative method to estimate impact loading during outdoor running. This study sought to compare both intra- and inter-subject correlations between vertical loading rates and PA measured at two body sites during running. Methods: Ground reaction force data were collected from 10 healthy adults (age = 23.6 3.8 years) during treadmill running at different speeds and inclination surfaces. Concurrently, PAs at the lateral malleoli and the distal tibia were measured using synchronized accelerometers. Results: We found significant positive intra-subject correlation between loading rates and PA at the lateral malleoli (r = 0.561–0.950, p < 0.001) and the distal tibia (r = 0.486–0.913, p < 0.001). PA measured at the lateral malleoli showed stronger correlation with loading rates (p = 0.004) than the measurement at the distal tibia. On the other hand, inter-subject variances were observed in the association between PA and vertical loading rates. The inter-subject variances at the distal tibia were 3.88±3.09 BW/s and 5.69±3.05 BW/s in VALR and VLIR respectively. Similarly, the inter-subject variances in the measurement at lateral malleoli were 5.24±2.85 BW/s and 6.67±2.83 BW/s in VALR and VLIR respectively. Conclusions: PA measured at lateral malleoli has stronger correlation with VALR or VILR than the measurement at distal tibia. Caution is advised when using PA to conduct inter-subject comparisons of vertical loading rates during running