Modification of the locomotor pattern when deviating from the characteristic heel-to-toe rolling pattern during walking.

PURPOSE: Humans are amongst few animals that step first on the heel, and then roll on the ball of the foot and toes. While this heel-to-toe rolling pattern has been shown to render an energetic advantage during walking, the effect of different foot contact strategies, on the neuromuscular control of adult walking gaits has received less attention. We hypothesised that deviating from heel-to-toe rolling pattern affects the energy transduction and weight acceptance and re-propulsive phases in gait along with the modification of spinal motor activity. METHODS: Ten subjects walked on a treadmill normally, then placed their feet flat on the ground at each step and finally walked on the balls of the feet. RESULTS: Our results show that when participants deviate from heel-to-toe rolling pattern strategy, the mechanical work increases on average 85% higher (F = 15.5; p < 0.001), mainly linked to a lack of propulsion at late stance. This modification of the mechanical power is related to a differential involvement of lumbar and sacral segment activation. Particularly, the delay between the major bursts of activation is on average 65% smaller, as compared to normal walking (F = 43.2; p < 0.001). CONCLUSION: Similar results are observable in walking plantigrade animals, but also at the onset of independent stepping in toddlers, where the heel-to-toe rolling pattern is not yet established. These indications seem to bring arguments to the fact that the rolling of the foot during human locomotion has evolved to optimise gait, following selective pressures from the evolution of bipedal posture.

The Single Leg Heel Rise Test-A Helpful Tool for Dance Science?: A Systematic Review.

BACKGROUND: Foot and ankle injuries are the most prevalent injuries in dance. The single leg heel-rise (SLHR) test is a simple tool to assess muscular endurance of the plantar flexors of the foot and is an increasingly popular manual muscle test in various areas of dance. Although the SLHR test has shown high reliability and validity in the medical field, no uniform description of this test exists in dance. OBJECTIVE: This systematic review aimed to identify parameters, outcome measures, purposes, and existing normative values of the SLHR test in the dance field. METHODS: Following the PRISMA guidelines, the electronic databases Scopus, PubMed, SPORTDiscus, EMBASE, CINAHL, and Cochrane were searched using a predefined search strategy up to June 2022. Studies were included if they reported screening, testing, or evaluation of either muscular endurance or strength of the calf muscle-tendon unit (MUT) in dancers using the SLHR test. The methodological quality of the studies was evaluated using a modified version of the Downs and Black Quality Index. RESULTS: A total of 180 studies were identified. Twelve studies comprising a total of 427 dancers met the inclusion criteria. Key testing parameters of the SLHR test varied widely or were not reported. The average quality rating of the reviewed studies was 12.9 (range 8 to 17) out of a possible 20 points. DISCUSSION: Although commonly used in test batteries, there are no standardized parameters of the SLHR test used in the dance field. Therefore, no generally applicable normative values could be established. CONCLUSION: Key parameters such as the precise execution of the heel rises should be reported in testing protocols. For the SLHR test to be a useful tool in dance, further research on the influence of dance style, age, and injuries to the calf MTU on this test is needed.

Sex differences in heel pad stiffness during in vivo loading and unloading.

Due to conflicting data from previous studies a new methodological approach to evaluate heel pad stiffness and soft tissue deformation has been developed. The purpose of this study was to compare heel pad (HP) stiffness in both limbs between males and females during a dynamic unloading and loading activity. Ten males and 10 females volunteered to perform three dynamic trials to unload and load the HP. The dynamic protocol consisted of three continuous phases: foot flat (baseline phase), bilateral heel raise (unloading phase) and foot flat (loading phase) with each phase lasting two seconds. Six retroreflective markers (3 mm) were attached to the skin of the left and right heels using a customised marker set. Three-dimensional motion analysis cameras synchronised with force plates collected the kinematic and kinetic data throughout the trials. Three-way repeated measures ANOVA together with a Bonferroni post hoc test were applied to the stiffness and marker displacement datasets. On average, HP stiffness was higher in males than females during the loading and unloading phases. ANOVA results revealed no significant differences for the stiffness and displacement outputs with respect to sex, sidedness or phase interactions (p > .05) in the X, Y and Z directions. Irrespective of direction, there were significant differences in stiffness between the baseline and unloading conditions (p < .001) but no significant differences between the baseline and loaded conditions (p = 1.000). Post hoc analyses for the marker displacement showed significant differences between phases for the X and Z directions (p < .032) but no significant differences in the Y direction (p > .116). Finally, females portrayed lower levels of mean HP stiffness whereas males had stiffer heels particularly in the vertical direction (Z) when the HP was both unloaded and loaded. High HP stiffness values and very small marker displacements could be valuable indicators for the risk of pathological foot conditions.

The effect of elevating the heels on spinal kinematics and kinetics during the back squat in trained and novice weight trainers.

This research assessed the influence of various heel elevation conditions on spinal kinematic and kinetic data during loaded (25% and 50% of body weight) high-bar back squats. Ten novice (mass 67.6 ± 12.4 kg, height 1.73 ± 0.10 m) and ten regular weight trainers (mass 66.0 ± 10.7 kg, height 1.71 ± 0.09 m) completed eight repetitions at each load wearing conventional training shoes standing on the flat level floor (LF) and on an inclined board (EH). The regular weight training group performed an additional eight repetitions wearing weightlifting shoes (WS). Statistical parametric mapping (SPM1D) and repeated measures analysis of variance were used to assess differences in spinal curvature and kinetics across the shoe/floor conditions and loads. SPM1D analyses indicated that during the LF condition the novice weight trainers had greater moments around L4/L5 than the regular weight trainers during the last 20% of the lift (P < 0.05), with this difference becoming non-significant during the EH condition. This study indicates that from a perspective of spinal safety, it appears advantageous for novice weight trainers to perform back squats with their heels slightly elevated, while regular weight trainers appear to realize only limited benefits performing back squats with either EH or WS.

Minimally invasive reconstruction technique for chronic Achilles tendon tears allows rapid return to walking and leads to good functional recovery.

PURPOSE: Chronic Achilles tendon tears, including chronic ruptures with end gap over 6 cm making end-to-end suturing impossible, can be treated with autologous hamstring graft reconstruction. The primary goal of this study was to present the biomechanical and long-term clinical results of recently developed minimally invasive Achilles tendon reconstruction technique. METHODS: Minimally invasive Achilles tendon reconstruction was applied to 8 foot and ankle cadaveric specimens as well as 18 patients with chronic Achilles tendon tears. Repaired cadavers were subjected to the biomechanical testing using a cyclic loading protocol. Patients with reconstructed Achilles tendon were subjected to the clinical, functional and isokinetic tests at 12 months after the treatment. RESULTS: All of tested Achilles cadaveric specimens survived 2 loading blocks (250 cycles of 10-100 N load followed by additional 250 cycles of 10-200 N load). With three specimens, it was possible to perform the third cyclic loading block with 20-300 N load and two specimens survived the fourth block with 20-400 N load. Therefore, a mean number of 838 cycles (±178) within the range of 509-1000 was recorded. Two specimens which survived all 1000 cycles were pulled to failure at 25 mm/s rate. The results obtained in the load to failure testing were as follows: 398 N and 608 N of maximum load. The results of functional heel rise endurance test and single leg hop for distance test indicated a decrease in the endurance and strength of the injured limb. However, the results of the weight-bearing lunge tests indicated no tendency for elongation of the Achilles tendon. A comparative analysis of the isokinetic test results for the non-injured and injured limb was revealed no statistically significant differences for every isokinetic test (n. s.), with significant difference for isometric strength parameters (p = 0.0006). CONCLUSIONS: The results of the biomechanical tests as well as 1-year extensive functional, clinical and isokinetic results of the minimally invasive technique for chronic Achilles tendon tears are encouraging. Patients returned to their normal physical activity, including sport pre-injury level in most cases. LEVEL OF EVIDENCE: III.

Analysis of Differences in the Degree of Biomechanical Adaptation according to Habituation to Different Heel Heights.

This study aims to comprehensively investigate whether there are any differences in the degree of biomechanical adaptation according to habituation to different heel heights. The biomechanical characteristics of 54 subjects in 3 groups habituated to three heel heights (low, medium-high, and high heels) were evaluated by the measurement of surface EMG, myotonometer (e.g., measurement of muscle tension), foot pressure, and lumbosacral angle, and comparative analysis was carried out to find out whether they showed differences in the comfort visual analog scale (comfort VAS). Wearers of high-heeled shoes (6 cm or more in heel height), in foot pressure comparison, showed significantly high peak pressure in the mask of the hallux, high maximum peak EMG in the gastrocnemius medius (GM), and a high percentage of maximum voluntary isometric contraction (%MVIC) in the plantar flexor. Wearers of low-heeled shoes (3 cm and below in heel height) showed the highest plantar peak pressure in the lateral forefoot and midfoot, the highest contact area in midfoot, the highest %MVIC in the plantar flexion and dorsiflexion of the tibialis anterior (TA), and the highest stiffness in the TA, and they showed the lowest static balance ability with eyes open (EO) among the three groups. It was found that there were significant differences between those habituated to high-heeled shoes and those not habituated to high-heeled shoes and that longtime wearing of high-heeled shoes brings about biomechanical adaptive changes in the human body.

Alternating Modulation of Subthalamic Nucleus Beta Oscillations during Stepping.

Gait disturbances in Parkinson's disease are commonly refractory to current treatment options and majorly impair patient's quality of life. Auditory cues facilitate gait and prevent motor blocks. We investigated how neural dynamics in the human subthalamic nucleus of Parkinsons's disease patients (14 male, 2 female) vary during stepping and whether rhythmic auditory cues enhance the observed modulation. Oscillations in the beta band were suppressed after ipsilateral heel strikes, when the contralateral foot had to be raised, and reappeared after contralateral heel strikes, when the contralateral foot rested on the floor. The timing of this 20-30 Hz beta modulation was clearly distinct between the left and right subthalamic nucleus, and was alternating within each stepping cycle. This modulation was similar, whether stepping movements were made while sitting, standing, or during gait, confirming the utility of the stepping in place paradigm. During stepping in place, beta modulation increased with auditory cues that assisted patients in timing their steps more regularly. Our results suggest a link between the degree of power modulation within high beta frequency bands and stepping performance. These findings raise the possibility that alternating deep brain stimulation patterns may be superior to constant stimulation for improving parkinsonian gait.SIGNIFICANCE STATEMENT Gait disturbances in Parkinson's disease majorly reduce patients' quality of life and are often refractory to current treatment options. We investigated how neural activity in the subthalamic nucleus of patients who received deep brain stimulation surgery covaries with the stepping cycle. 20-30 Hz beta activity was modulated relative to each step, alternating between the left and right STN. The stepping performance of patients improved when auditory cues were provided, which went along with enhanced beta modulation. This raises the possibility that alternating stimulation patterns may also enhance beta modulation and may be more beneficial for gait control than continuous stimulation, which needs to be tested in future studies.

Lower leg morphology in runners: forefoot strikers have longer heels but not bigger muscles than rearfoot strikers.

Foot strike pattern used during running may relate to lower leg morphology. We tested the hypotheses that forefoot strike (FFS) runners have longer plantarflexor moment arms (r) and larger plantarflexor muscles than rearfoot strike (RFS) runners. FFS runners had 17% longer r than RFS runners, but all runners had similarly sized medial and lateral gastrocnemius (MG and LG) muscles. Because muscle size also depends on activation pattern ( Ahn et al., 2011), we compared MG:LG activation bias during walking in 24 runners and 23 sedentary subjects. Half of all subjects activated their MG and LG muscles equally ('unbiased') while walking, while the other half activated their MG more strongly than their LG muscles ('MG-biased'). Unbiased sedentary subjects had 16-23% smaller MG muscles compared with MG-biased sedentary subjects, unbiased runners and MG-biased runners. Muscle contraction dynamics during FFS running may balance the effects of longer plantarflexor moment arms in determining MG and LG muscle size.

Forefoot and heel take-off strategies result in different distribution of lower extremity work during landings.

Previous research suggests that landing mechanics may be affected by the mechanics of the preceding jump take-off. The purpose of the present study was to investigate whether jump take-off mechanics influence the subsequent landing mechanics. Female volleyball (n = 17) and ice hockey (n = 19) players performed maximal vertical jumps with forefoot and heel take-off strategies. During forefoot and heel jumps, participants were instructed to shift their weight to their forefoot or heel, respectively, and push through this portion of the foot throughout the jump. Jump mechanics were examined using 3D motion analysis, where lower extremity net joint moment (NJM) work, NJM, and segment angles were compared between forefoot and heel jumps using multivariate ANOVA. During jump take-off, participants performed more positive ankle plantar flexor and knee extensor NJM work in forefoot compared to heel jumps (P < 0.05). From initial foot contact to foot flat, participants performed more negative ankle plantar flexor and hip extensor NJM work during heel compared to forefoot jumps (P < 0.05). The present results demonstrate that using a heel take-off strategy results in a different distribution of lower extremity NJM work and NJM during landing compared to landings following forefoot jumps.

Biomechanical differences in double poling between sexes and level of performance during a classical cross-country skiing competition.

Biomechanical differences in double poling (DP) between sex and performance level were investigated in female and male cross-country skiers during a classical race (10/15 km). Skiers were divided into faster and slower on basis of race performance: females faster (n=20), females slower (n=20), males faster (n=20), and males slower (n=20). Based on video analysis while DP in a flat section of the track, joint and pole angles at pole plant (PP) and pole-off, cycle characteristics and the use and coordination pattern of heel-raise (raise of heels from the ground to have a higher body position at PP) were analysed. Faster females and males had 4.3% and 7.8% higher DP velocity than their slower counterparts (both P<0.001). Faster males had 6.5% longer cycles than slower males (P<0.001). Faster skiers stopped heel-raise later than slower skiers (females: 2.0±3.4% vs. -1.0±3.5%, P<0.05; males: 3.9±2.4% vs. 0.8±3.2% of cycle time in relation to PP, P<0.001). At PP, faster skiers and male skiers had a smaller pole angle and greater ankle to hip and ankle to shoulder angle with respect to vertical, resulting in a more distinct forward body lean. However, the majority of the differences are likely due to higher DP velocity.

Heel-Raised Foot Posture Does Not Affect Trunk and Lower Extremity Biomechanics During a Barbell Back Squat in Recreational Weight lifters.

Lee, S-P, Gillis, CB, Ibarra, JJ, Oldroyd, DF, and Zane, RS. Heel-raised foot posture does not affect trunk and lower extremity biomechanics during a barbell back squat in recreational weight lifters. J Strength Cond Res 33(3): 606-614, 2019-It is claimed that weightlifting shoes with a raised heel may lead to a more upright trunk posture, and thus reduce the risk of back injuries during a barbell back squat. These proclaimed biomechanical effects have not been thoroughly investigated. The purpose of this study was to compare trunk and lower extremity biomechanics during barbell back squats in three foot postures. Fourteen recreational weight lifters (7 men and 7 women) between the ages of 18 and 50 years performed barbell back squats in three conditions (barefoot on a flat surface, barefoot on a heel-raised platform, and wearing heel-raised weightlifting shoes) at 80% of their 1 repetition maximum. Surface electromyography was used to assess the activation of the knee extensors and paraspinal muscles at L3 and T12 spinal levels. A 3D motion capture system and an electrogoniometer recorded the kinematics of the thoracic spine, lumbar spine, and knee during the back squat to a depth where the hip was at least at the same level to the knee. Results indicated that none of the heel-raised foot postures significantly affected trunk and lower extremity muscle activation (thoracolumbar paraspinal [p = 0.52], lumbar paraspinal [p = 0.179], knee extensor [p = 0.507]) or the trunk angles (thoracolumbar spine [p = 0.348], lumbar spine [p = 0.283]) during the squat. Our results demonstrated that during barbell back squats, heel-raised foot postures do not significantly affect spinal and knee extensor muscle activations, and trunk and knee kinematics. Heel-raised weightlifting shoes are unlikely to provide significant protection against back injuries for recreational weight lifters during the barbell back squat.

Younger Total Knee Replacement Patients Do Not Demonstrate Gait Asymmetry for Heel Strike Transient or Knee Joint Moments That Are Observed in Older Patients.

Gait asymmetry is observed after total knee replacement, often leading to excessive forces at the contralateral limb. The number of total knee replacement procedures has increased substantially over the past 2 decades, particularly among younger patients. Relatively little is known regarding these younger patients (<65 y), specifically, with respect to gait asymmetry. The purpose of this study was to investigate if age affects gait asymmetry after unilateral total knee replacement. Three-dimensional analysis of 10 walking trials was collected from the following 4 groups: younger patient (age: 54.3 [7.9] y), younger control (age: 55.2 [4.0] y), older patient (age: 76.9 [4.7] y), and older control (age: 77.7 [4.1] y). The older patients, but not any of the other groups, demonstrated a significantly larger heel strike transient and peak knee adduction moment at the nonsurgical compared with the surgical limb. The observed gait pattern of the younger patients resembled that of the younger controls, rather than the older patients. The greater loading of the nonsurgical limb for the older patients could contribute to the initiation or further progression of osteoarthritic degeneration in the contralateral knee; these asymmetries were not observed for the younger patients.

The effect of Aloe Vera gel on prevention of pressure ulcers in patients hospitalized in the orthopedic wards: a randomized triple-blind clinical trial.

BACKGROUND: One of the most common orthopedic problems is the incidence of pressure ulcer followed by immobility. This study aimed to investigate the effect of Aloe Vera gel on the prevention of pressure ulcer in patients hospitalized in the orthopedic ward. METHOD: This study is a randomized, triple-blind clinical trial which was done on 80 purposefully selected patients in orthopedic ward in Arak town, Iran, 2016. Patients were randomly assigned into two intervention and control groups based on blocking sampling method. In each group the routine daily cares to prevent bed sores were performed by nurses. In the intervention group in addition to routine nursing care to prevent bed sores, twice a day (hours of 9 and 21) pure Aloe Vera gel on the areas of hip, sacrum and heel were rubbed, but in the control group placebo (gel of water and starch) were used. Then sacral, hip and heel of both groups on days 3, 7 and 10 for of signs of pressure ulcers was evaluated. RESULTS: The mean age of patients in the control group was (42.34 ± 12.19) and in the intervention group Was (41.71 ± 11.50) years, respectively. In the intervention group 1 patient afflicted with sore of hip and two people with sacral pressure ulcer. In the control group 3 patients affiliated with sore of hip, 8 people with sacral pressure ulcer, and 1 person had pressure sore of heel. Analysis of the data showed that both groups had statistically significant differences in the incidence of pressure ulcers (P = 0.047). This means that Aloe Vera gel could prevent the occurrence of pressure ulcers in the intervention group. CONCLUSION: Due to the effect of Aloe Vera gel to prevent a rise in temperature, non-blanchable redness, swelling and pain of the skin of regions under study in hospitalized patients in the orthopedic ward, applying of it toward the prevention of pressure ulcers in patients at risk of pressure ulcer development is recommended. TRIAL REGISTRATION: This study was registered in Iranian Registry of Clinical. Trials in 07/09/2016 with the IRCT ID: IRCT2016051027825N1 .

Altered stiffness of microchamber and macrochamber layers in the aged heel pad: Shear wave ultrasound elastography evaluation.

BACKGROUND/PURPOSE: To compare shear modulus of heel pad microchamber and macrochamber layers between young and elderly people using shear wave ultrasound elastography (SWUE), with the intent to clarify age-related changes. METHODS: This single-center prospective cross-sectional study was conducted between March, 2014 and March, 2016. Shear modulus of entire heel pad (Gentire), macrochamber layer (Gmac), and microchamber layer (Gmic) were measured with SWUE. RESULTS: Elderly participants (15 men, 15 women; age = 66.9 ± 6.2 years) had significantly higher Gmic (103.8 ± 20.7 vs. 60.1 ± 9.8 kPa; p < 0.001) and Gentire (39.4 ± 10.5 vs. 34.1 ± 5.4 kPa; p = 0.005), but a significantly lower Gmac (21.7 ± 7.5 vs. 27.9 ± 4.9 kPa; p < 0.001) compared with those of young participants (15 men, 15 women; age = 26.4 ± 2.9 years). Positive correlations were observed between age and Gmic (r = 0.79, p < 0.001) and between age and Gentire (r = 0.28, p = 0.03), and negative correlation between age and Gmac (r = -0.46, p = 0.001). CONCLUSION: SWUE revealed that the heel pad macrochamber layer was slightly softer but the microchamber layer was exaggeratedly stiffer, making the entire heel pad stiffer in the elderly group than in the younger group, implying age-related compensation in heel pad layers to retain foot function.

Effect of Compression Garments on Controlled Force Output After Heel-Rise Exercise.

Kato, E, Nakamura, M, and Takahashi, H. Effect of compression garments on controlled force output after heel-rise exercise. J Strength Cond Res 32(4): 1174-1179, 2018-The purpose of this study was to elucidate the effects of compression garments (CG) on controlled force output after strenuous exercise. Sixteen healthy volunteers completed trials both with CG and without CG (control trial: CON) on 2 separate, random days which were at least 1 month apart. Both trials required participants to perform heel-rise exercises from maximal dorsiflexion to maximal plantar flexion 20 times with a single leg. The subjects repeated 3 sets of the exercise and took a rest for 2 minutes between sets. Before and after the heel-rise exercise, mechanical (stiffness) and architectural properties of the gastrocnemius medialis muscle were evaluated using the ultrasound method. Also, isometric maximal voluntary contraction (MVC) of plantar flexion was measured, and the subjects maintained 20% MVC of plantar flexion torque for 20 seconds as steadily as possible (steadiness task) as an index of force control. Repeated 2-way analysis of variance analysis (CG/CON × time) indicated that all the parameters declined immediately after heel-rise exercise in both CG and CON trials. Maximal voluntary contraction did not show different tendencies between CG and CON trials, but muscle stiffness and steadiness declined less in CG than CON (p < 0.05). In conclusion, CG are considered to positively benefit controlled force output after strenuous exercise.

Characteristics of Plantar Loads During Walking in Patients with Knee Osteoarthritis.

BACKGROUND Knee osteoarthritis (KOA) is a common disease that can change the load on lower limbs during walking. Plantar loads in patients with KOA may provide a basis for clinical decisions regarding footwear and foot orthoses. This study aimed to compare plantar loads in females with and without KOA during gait. MATERIAL AND METHODS Plantar pressure during walking was recorded in 23 females with KOA and 23 females without KOA. Maximum force (MF), contact area (CA), and peak pressure (PP) were measured at 7 different regions underneath the foot, named heel (M1), midfoot (M2), first metatarsophalangeal joint (MPJ) (M3), second MPJ (M4), third to fifth MPJ (M5), hallux (M6), and lesser toes (M7). RESULTS PPs for M2 and (M3) in females with KOA were higher than those in females without KOA. High PPs were also found in females with KOA for M2, M3, and M4. CONCLUSIONS Increased plantar loading in females with KOA may lead to foot pronation and gait changes during walking. Plantar loading may be offered to patients with KOA when considering footwear and foot orthoses.

In vivo skin moisturizing measurement by high-resolution 3 Tesla magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) is rarely used for the exploration of skin, even if studies have validated both feasibility of skin MRI and its interest for anatomical, physiological, and biochemical study of the skin. The purpose of this study is to explore moisturizing of the different skin layers using 3-T scan. METHODS: An MRI of the heel's skin was performed using a 23 mm coil diameter on a 3T scan with a FFE (Fast Field Echo) 3D T1-weighted sequence and a TSE (Turbo Spin Echo) calculation T2-weighted sequence (pixels size of respectively 60 and 70 µm). This study was conducted on 35 healthy volunteers, who were scanned before applying moisturizer topic and 1 h after applying it. Region of interest in the stratum corneum, the epidermis and the dermis were generated on the T2 mapping. The thickness of each layer was measured. The T1 sequence allowed accurate cross-examination repositioning to ensure the comparability of the measurements. RESULTS: Among the 35 cases, two were excluded from the analysis because of movement artifacts. Measurements before and after moisturizer topic application displayed a T2 increase of 48.94% (P < 0.0001) in the stratum corneum and of 5.45% (P < 0.0001) in the epidermis yet without significant difference in the dermis. There was no significant link between the thickness of the stratum corneum and the T2 increase. However, there was a strong correlation between the thickness of the stratum corneum and the thickness of the epidermis (P < 0.001; rhô=0.72). CONCLUSION: High-resolution MRI allows fine exploration of anatomical and physiological properties of the skin and can further be used to extend the studies of skin hydration.

Joint stiffness and running economy during imposed forefoot strike before and after a long run in rearfoot strike runners.

Research has focused on the effects of acute strike pattern modifications on lower extremity joint stiffness and running economy (RE). Strike pattern modifications on running biomechanics have mostly been studied while runners complete short running bouts. This study examined the effects of an imposed forefoot strike (FFS) on RE and ankle and knee joint stiffness before and after a long run in habitual rearfoot strike (RFS) runners. Joint kinetics and RE were collected before and after a long run. Sagittal joint kinetics were computed from kinematic and ground reaction force data that were collected during over-ground running trials in 13 male runners. RE was measured during treadmill running. Knee flexion range of motion, knee extensor moment and ankle joint stiffness were lower while plantarflexor moment and knee joint stiffness were greater during imposed FFS compared with RFS. The long run did not influence the difference in ankle and knee joint stiffness between strike patterns. Runners were more economical during RFS than imposed FFS and RE was not influenced by the long run. These findings suggest that using a FFS pattern towards the end of a long run may not be mechanically or metabolically beneficial for well-trained male RFS runners.

Changes in hindfoot alignment after total knee arthroplasty in knee osteoarthritic patients with varus deformity.

PURPOSE: Hindfoot alignment can affect the weight-bearing kinematics of the knee joint in patients undergoing total knee arthroplasty (TKA). This study evaluated the change in hindfoot alignment after TKA by prospectively analysing the correlation between the knee joint and the hindfoot deformity, the post-operative improvement in the hindfoot deformity, and the long-term post-operative changes in hindfoot alignment. METHODS: This study included 195 knees from 117 patients with osteoarthritis who underwent TKA between 2012 and 2013. The mechanical alignment angle of the knee joint and the hindfoot alignment angle were measured preoperatively and 6 weeks, 1, and 2 years post-operatively. The patients were divided into two groups according to the severity of the preoperative knee joint deformity: <10° varus (group 1, N = 81) and ≥10° varus (group 2, N = 114). The preoperative and post-operative radiologic parameters of the axis of the knee joint and hindfoot were evaluated, and the results were compared. A Spearman correlation analysis was used to assess the differences in both the mechanical alignment and the hindfoot alignment pre- and post-operatively. RESULTS: After TKA, the hindfoot valgus deformity improved from 5.2° (±3.8) valgus to 2.1° (±3.9) valgus. At 6 weeks post-operatively, the hindfoot alignment angle was 1.4° (±3.5) valgus and 2.5° (±4.1) valgus in group 1 and group 2, respectively; the difference between the two groups was not statistically significant. Hindfoot alignment showed greater valgus with increasing varus of the mechanical alignment of the knee joint preoperatively (-0.484, p < 0.001) and post-operatively (-0.147, p = 0.040). The post-operative 1- and 2-year hindfoot alignment angles were 2.2° (±4.2) valgus and 2.2° (±4.1) valgus, respectively. None of the differences between the post-operative hindfoot alignment angles were statistically significant. CONCLUSIONS: The stable improvement in the hindfoot deformity after TKA demonstrates that a valgus deformity of the hindfoot in a patient with a varus knee joint deformity does not require preoperative correction. In patients with a residual hindfoot deformity and pain 6 weeks after TKA, active treatment should be considered because no further improvement can be expected. LEVEL OF EVIDENCE: Prospective cohort study, Level II.

The Effects of a Heel Wedge on Hip, Pelvis and Trunk Biomechanics During Squatting in Resistance Trained Individuals.

Barbell back squats are a popular exercise for developing lower extremity strength and power. However, this exercise has potential injury risks, particularly to the lumbar spine, pelvis, and hip joint. Previous literature suggests heel wedges as a means of favorably adjusting trunk and pelvis kinematics with the intention of reducing such injury risks. Yet no direct biomechanical research exists to support these recommendations. Therefore, the purpose of this study was to examine the effects of heel wedges compared with barefoot on minimally loaded barbell back squats. Fourteen trained male participants performed a barbell back squat in bare feet or with their feet raised bilaterally with a 2.5-cm wooden block while 3-dimensional kinematics, kinetics, and electromyograms were collected. The heel wedge condition elicited significantly less forward trunk flexion angles at peak knee flexion, and peak external hip joint moments (p ≤ 0.05) compared with barefoot conditions. However, no significant differences were observed between conditions for trunk and pelvis angle differences at peak knee flexion (p > 0.05). Lastly, no peak or root mean square differences in muscle activity were elicited between conditions (p > 0.05). Our results lend support for the suggestions provided in literature aimed at using heel wedges as a means of reducing excessive forward trunk flexion. However, the maintenance of a neutral spine, another important safety factor, is not affected by the use of heel wedges. Therefore, heel wedges may be a viable modification for reduction of excessive forward trunk flexion but not for reduction in relative trunk-pelvis flexion during barbell back squats.