Günther Schlee

Foot sole skin temperature affects plantar foot sensitivity

OBJECTIVE Factors like age and polyneuropathic diseases are known to influence foot sensitivity and are considered when applying quantitative sensory testing. However, the effects of temperature on foot sensitivity are controversial. Therefore, the aim of this study was to investigate the influence of different foot sole temperature on vibration sensitivity of healthy subjects. METHODS Forty healthy subjects (20 male, 20 female) were analyzed. Vibration thresholds were measured at three anatomical locations (Heel, 1st Metatarsal Head and Hallux) of both feet at 200Hz. Thresholds were measured at initial baseline temperature and after cooling/warming of the foot skin 5-6 degrees C. Comparisons between baseline and cooled/warmed thresholds as well as between genders were performed. RESULTS There were no significant differences in vibration thresholds when comparing men and women. Thresholds were significantly higher after skin cooling for at all anatomical locations. After skin warming, thresholds were significantly lower at all measured anatomical locations. CONCLUSIONS Small temperature changes significantly influence vibration sensitivity of healthy subjects and should be controlled during collection of foot sensitivity data. SIGNIFICANCE The control of temperature is an important factor to enhance the quality of data acquired with quantitative sensory testing.

Whole body vibration training reduces plantar foot sensitivity but improves balance control of healthy subjects

The goal of this study was to investigate the effects of short-time whole body vibration (WBV) training on foot vibration sensitivity of healthy subjects. Furthermore, the effects of WBV on a balance task (one-leg stand) were also evaluated. 30 young healthy subjects participated in the study. Vibration perception thresholds and balance were measured prior and after a single session of a 4-min WBV training (27Hz, 2mm horizontal amplitude). Thresholds were measured at 200Hz at three anatomical locations of the plantar foot area (first and fifth metatarsal heads and heel). Body balance was quantified using the length as well as the area described by the center of pressure (COP) at quiet, one-leg standing. Whereas vibration thresholds significantly increased after WBV training at all measured locations, there was a significant decrease in the balance related parameters after WBV exercise. The results indicate that the above-threshold, sinusoidal vibration used during WBV training is not an adequate strategy to stimulate/improve vibration sensitivity. The improvements seen in balance after WBV are likely to have neuromuscular mechanisms as their main component rather than increased foot sensitivity.

Short-time lower leg ischemia reduces plantar foot sensitivity

The aim of this study was to investigate the effects of short-time blood flow occlusion on plantar foot vibration sensitivity of healthy young adults. 39 subjects (20 female; 19 male) participated in the study. Blood flow reduction was evoked with a pneumatic tourniquet, placed about 10 cm above the popliteus cavity. Vibration thresholds (200 Hz) were measured at three anatomical locations of the plantar foot (heel, first metatarsal head and hallux) in three different cuff pressure conditions: baseline (0 mmHg), low (50 mmHg) and high (150 mmHg). Each pressure condition was held for 4 min prior to vibration threshold measurements. No reperfusion time was allowed between conditions. The results show a significant increase in vibration thresholds measured at all anatomical locations in the high pressure condition (150 mmHg), whereas low pressure (50 mmHg) caused a significant threshold increase only at the hallux, compared to baseline (0 mmHg) measurements. Short-time blood flow occlusion seems to affect the afferent transmission of vibration stimuli from Vater-Pacini corpuscles, resulting in decreased plantar foot sensitivity. The present study provides an insight into initial adaptations caused by reduced blood flow in plantar foot sensitivity of healthy young adults.

Children with ADHD Show No Deficits in Plantar Foot Sensitivity and Static Balance Compared to Healthy Controls.

The goal of this study was to investigate plantar foot sensitivity and balance control of ADHD (n=21) impaired children compared to age-matched healthy controls (n=25). Thresholds were measured at 200 Hz at three anatomical locations of the plantar foot area of both feet (hallux, first metatarsal head (METI) and heel). Body balance was quantified using the length, area and velocity described by the center of pressure (COP) during two-legged as well as one-legged stand (right and left legs). The comparison of vibration thresholds showed no differences between ADHD and healthy children at all anatomical locations of both feet. Whereas COP excursion and area were significantly lower in ADHD subjects compared to the healthy controls during two-legged stand, no differences were found in those variables when balancing on one leg. No differences in COP velocity between ADHD and healthy children were found in any analyzed conditions. The results indicate that the unusual and simple test situation may have increased the perception of vibration stimuli by the ADHD children. Furthermore, ADHD subjects seem to be less variable when performing simple tasks than healthy controls.

Balance control and muscle activity in various unstable shoes compared to barefoot during one-leg standing

The purpose of this study was to compare muscle activity and balance control of young healthy subjects during one-leg standing using various unstable shoes, a stable reference running shoe and barefoot condition. Twenty athletic female subjects participated in this study. The protocol consisted of quiet one-leg standing measured in six randomized conditions: four different unstable shoes, reference shoe and barefoot. The data were measured using the Pedar-X® insole system and a surface electromyography (EMG) system. Activity of eight muscles of the right leg was measured and integrated EMG (IEMG) and root mean square (RMS) values were calculated. For the balance control analysis, centre of pressure (CoP) total, medial–lateral and anterior–posterior excursions were calculated. A descriptive analysis and also one-way repeated-measures ANOVA (α = 0.05) and post-hoc tests were performed. The results indicate larger CoP total excursion as well as CoP medial–lateral excursion in barefoot compared to all shoe conditions (p < 0.05), whereas no differences were observed within the shoe conditions. Higher muscle activity (IEMG) was identified for the lateral gastrocnemius, vastus medialis and rectus femoris during barefoot standing with no difference between shoe conditions. No differences in RMS values could be observed for all analysed conditions. In conclusion, this study could not find any relevant differences between the shoe conditions for any of the analysed variables. Surprisingly, the barefoot condition showed the greatest instability (CoP excursions) and the highest muscle activity compared to all shoes analysed in the study. Further studies with unstable shoes are needed to investigate their instability effects.

Plantar pressure distribution, rearfoot motion and ground reaction force after long distance running

The objective of this study was to investigate ground reaction forces (GRF), rearfoot motion and plantar pressure distribution (PPD) variables before and after long distance treadmill running in a commercially available running shoe in a standardized laboratory condition. Sample was composed of 19 subjects of both genders. Data collection was performed in two phases: (1) physiological test, in order to determine the speed in which the long distance running protocol was performed and (2) biomechanical test: PPD, rearfoot motion and ground reaction force parameters were measured before and after a 45-min treadmill run. A paired sample ‘t-test’ was used to compare the data between the pre and post-measurements (α = 0.05). The values of maximum pronation velocity showed a significant increase (P < 0.01). No significant changes were observed in the remaining parameters. There seem to be a hierarchical control of biomechanical parameters during long distance running, in which impact reduction is more important than the precise control of rearfoot motion.

Effect of cooling foot sole skin receptors on achilles tendon reflex

Introduction: This study investigated whether a controlled reduction of foot sole temperature affects the Achilles tendon stretch reflex and plantar flexion. Methods Five stretch reflexes in 52 healthy subjects were evoked by Achilles tendon taps. Short latency responses of 3 muscles of the lower limb and maximal force of plantar flexion were analyzed. Foot sole hypothermia was induced by a thermal platform at various foot temperature conditions: Stage I (25°C), Stage II (12°C), Stage IIIa (0°C), and Stage IIIb (0°C). Results Reduction of plantar cutaneous inputs resulted in a decrease in amplitude of medial gastrocnemius and soleus as well as delays in time to maximal force of plantar flexion. Medial gastrocnemius, lateral gastrocnemius, and soleus were affected differently by induced cooling. No inhibition effects in reflexes were observed at 12°C. Conclusions The results suggest that input on the plantar foot sole participates complementarily in the Achilles stretch reflex Muscle Nerve, 2015. Muscle Nerve 53: 965–971, 2016

Long term whole body vibration training has no effects on plantar foot sensitivity and balance control

Background Below-threshold vibration together with low-level mechanical noise (stochastic resonance) is known to have positive effects on plantar foot sensitivity and balance control [1]. However, the effects of abovethreshold stimulation on both variables are still not proved. The goal of this study was to investigate the effects of whole body vibration (WBV) training, characterized by above threshold stimulation, on plantar foot sensitivity and balance control of young healthy subjects. Materials and methods 38 subjects of both genders were divided in training (WBV, n=27) and control (CG, n=11) groups. Plantar foot vibration sensitivity and balance were measured before and after a 6-week WBV training, in which subjects were exposed weekly to three bouts of vibration stimuli (27 Hz vibration frequency; 2 mm horizontal amplitude), with duration from 5.30 up to 8.30 min. Vibration sensitivity was measured at the heel, first and fifth metatarsal heads and hallux of both feet. Balance was measured with subjects standing on one leg (right and left legs) during 20 s with eyes open. Vibration thresholds [μm] and CoP excursion [mm] before and

Golf footwear: foot dimensions and functional fit

The personalised insole was more comfortable over short and medium term use, especially in the midfoot, heel and fit aspects. Most of the biomechanical differences between the two insoles occurred at the ankle joint and during the impact phase of ground contact, with the personalised insole showing reduced impact peak, mean loading rate, ankle dorsiflexion at foot strike and maximum rearfoot eversion. These results support the potential benefits of using personalised insoles for running over sustained periods of at least 3 months.

Proprioceptive deficit after total elbow arthroplasty: an observational study

BACKGROUND During total elbow arthroplasty (TEA), most of the joint capsule is removed, including many mechanoreceptors important for proprioception, which potentially limits the patients postoperative functional recovery. We quantified proprioceptive loss by measuring the threshold to detection of passive motion (TTDPM) in patients after unilateral TEA compared with the contralateral side. METHODS A continuous passive motion device moving the elbow at 0.5°/s was used to evaluate TTDPM in 8 patients (mean ± standard deviation age, 69.1 ± 9.93 years) at least 1 year after unilateral semiconstricted linked TEA for a range of diagnoses. Elbow function after TEA was assessed using the Mayo Elbow Performance Scale. RESULTS Postsurgical Mayo scores revealed 4 excellent results, 2 good, and 2 poor. The TTDPM in the elbows undergoing arthroplasty was still significantly higher compared with the contralateral elbow at 4.2° (15.6  ± 6.9 seconds vs. 7.2  ± 2.6 seconds; D = 3.23, P = .01) equivalent to 8.4 seconds. CONCLUSIONS Patients who have had severe joint disease requiring semiconstrained TEA have long-term proprioception deficits. A more conservative technique that maximally preserves insertions and soft tissues, might minimize upper limb proprioceptive deficit.