Pedro Pérez-Soriano

Plantar pressures determinants in mild Hallux Valgus

While podobarometric techniques have been applied to the study of pressures in Hallux Valgus (HV), little is known about its clinical and radiological determinants. So, the aim of the present study was to determine the plantar pressure pattern in participants with mild HV, comparing to a control group, and their clinical and anthropometric determinants. Biofoot/IBV(®) in-shoe system was used to evaluate 79 participants with mild HV. Computerized measurements of the 1st intermetatarsal angle (IMA) and the hallux abductus angle (HAA) were made on antero-posterior radiographs. The clinical outcome was assessed using the AOFAS score. The dependent baropodometric variables and the independent clinical and anthropometric variables were subjected to a multiple regression analysis. In both groups, the highest average pressure was in the 2nd metatarsal head (MTH). The mean pressure under the Hallux was significantly higher in HV group (controls, 146.5±92.5kPa; HV, 328.5±113.2kPa; p<0.001). An 18.6% of average pressure under the 1st MTH was accounted for pain, first ray alignment and total AOFAS score. Variations of the HAA explained 26.8% of the mean Hallux pressure. Women with mild HV present with pathologically increased pressure under the Hallux, which is caused by the altered alignment of the first ray. Pain and clinical result were associated with the pressure under the 1st MTH and the remaining variables were only moderate predictors of dynamic plantar pressures.

Relationship between skin temperature and muscle activation during incremental cycle exercise.

While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<-0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test.

Effect of overground vs treadmill running on plantar pressure: Influence of fatigue

The differences produced when running on a treadmill vs overground may call into question the use and validity of the treadmill as a piece of equipment commonly used in research, training, and rehabilitation. The aim of the present study was to analyze under pre/post fatigue conditions the effect of treadmill vs overground on plantar pressures. Twenty-seven recreational runners (17 men and 10 women) ran on a treadmill and overground at two speeds: S1=3.33 m/s and S2=4.00 m/s, before and after a fatigue protocol consisting of a 30-min run at 85% of their individual maximal aerobic speed (MAS). Contact time (CT in seconds), peak pressure (PP in kPa), and relative load (RL in %) were analyzed under nine foot zones of the left foot using an in-shoe plantar pressure device. A two-way repeated measures ANOVA showed that running on a treadmill increases CT (7.70% S1 and 9.91% S2), modifies the pressure distribution and reduces PP (25.98% S1 and 31.76% S2), especially under the heel, medial metatarsals, and hallux, compared to running overground. Moreover, on both surfaces, fatigue (S2) led to a reduced stride frequency (2.78%) and reduced PP on the lateral heel and hallux (15.96% and 16.35%, respectively), and (S1) increased relative load on the medial arch (9.53%). There was no significant interaction between the two factors analyzed (surface and fatigue). Therefore, the aforementioned surface effect, which occurs independently of the fatigue state, should be taken into account when interpreting the results of studies that use the treadmill in their experimental protocols, and when prescribing physical exercise on a treadmill.

Effects of graduated compression stockings on skin temperature after running.

High skin temperatures reduce the thermal gradient between the core and the skin and they can lead to a reduction in performance and increased risk of injury. Graduated compression stockings have become popular among runners in the last years and their use may influence the athletes thermoregulation. The aim of this study was to investigate the effects of graduated compression stockings on skin temperature during running in a moderate indoor environment. Forty-four runners performed two running tests lasting 30min (10min of warm-up and 20min at 75% of their maximal aerobic speed) with and without graduated compressive stockings. Skin temperature was measured in 12 regions of interest on the lower limb by infrared thermography before and after running. Heart rate and perception of fatigue were assessed during the last minute of the running test. Compression stockings resulted in greater increase of temperature (p=0.002 and ES=2.2, 95% CI [0.11-0.45°C]) not only in the body regions in contact (tibialis anterior, ankle anterior and gastrocnemius) but also in the body regions that were not in contact with the garment (vastus lateralis, abductor and semitendinosus). No differences were observed between conditions in heart rate and perception of fatigue (p>0.05 and ES<0.8). In conclusion, running with graduated compression stockings produces a greater increase of skin temperature without modifying the athletes heart rate and perception of fatigue.

Effects of treadmill running and fatigue on impact acceleration in distance running

The effects of treadmill running on impact acceleration were examined together with the interaction between running surface and runners fatigue state. Twenty recreational runners (11 men and 9 women) ran overground and on a treadmill (at 4.0 m/s) before and after a fatigue protocol consisting of a 30-minute run at 85% of individual maximal aerobic speed. Impact accelerations were analysed using two lightweight capacitive uniaxial accelerometers. A two-way repeated-measure analysis of variance showed that, in the pre-fatigue condition, the treadmill running decreased head and tibial peak impact accelerations and impact rates (the rate of change of acceleration), but no significant difference was observed between the two surfaces in shock attenuation. There was no significant difference in acceleration parameters between the two surfaces in the post-fatigue condition. There was a significant interaction between surface (treadmill and overground) and fatigue state (pre-fatigue and post-fatigue). In particular, fatigue when running overground decreased impact acceleration severity, but it had no such effect when running on the treadmill. The effects of treadmill running and the interaction need to be taken into account when interpreting the results of studies that use a treadmill in their experimental protocols, and when prescribing physical exercise.

Nordic Walking Practice Might Improve Plantar Pressure Distribution

Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred and 20% faster), and under two walking conditions (NW vs. normal walking). In comparison to normal walking, NW experience led to a significant (p < .05) pressure reduction of about 50% on the central metatarsals. No significant increases were detected in other foot regions. The differences between experienced and beginners during normal walking, including a 40% pressure reduction on the metatarsal area, suggests that regular NW practice might also have a beneficial effect on plantar pressure when walking without poles.

Effect of custom-made and prefabricated insoles on plantar loading parameters during running with and without fatigue

Abstract Controversy exists whether custom-made insoles are more effective in reducing plantar loading compared to prefabricated insoles. Forty recreational athletes ran using custom-made, prefabricated, and the original insoles of their running shoes, at rest and after a fatigue run. Contact time, stride rate, and plantar loading parameters were measured. Neither the insole conditions nor the fatigue state modified contact time and stride rate. Addressing prevention of running injuries, post-fatigue loading values are of great interest. Custom-made insoles reduced the post-fatigue loading under the hallux (92 vs. 130 kPa, P < 0.05), medial midfoot (70 vs. 105 kPa, P < 0.01), and lateral midfoot (62 vs 96 kPa, P < 0.01). Prefabricated insoles provoked reductions in post-fatigue loading under the toes (120 vs. 175 kPa, P < 0.05), medial midfoot (71 vs. 105 kPa, P < 0.01), and lateral midfoot (68 vs. 96 kPa, P < 0.01). Regarding both study insoles, custom-made insoles reduced by 31% and 54% plantar loading under the medial and lateral heel compared to the prefabricated insoles. Finally, fatigue state did not influence plantar loading regardless the insole condition. In long-distance races, even a slight reduction in plantar loading at each foot strike may suppose a significant decrease in the overall stress experienced by the foot, and therefore the use of insoles may be an important protective mechanism for plantar overloading.

Handgrip strength and hand dimensions in high-level inter-university judoists

Background Handgrip strength plays a major role in many sports. In Judo, a single grasp allows the judoka to attack, defend and counter-attack through different movements in a span of four to six directions. Some general and hand-specific anthropometric measurements have been positively related to handgrip strength. Therefore, the aim of this study was the influence of general and hand anthropometric parameters in handgrip strength and sport achievement. Material & Methods: Fifty four judokas aged 19–25 years participants of the Inter-University Championship of Spain 2009 took part in this study. Body height and body mass were measured and body mass index was calculated as general anthropometric parameters. Three groups of hand specific parameters were measured: finger spans, finger lengths and hand perimeters. The handgrip strength was measured by digital dynamometer in both hands. Results: The general and some hand-specific (finger lengths, hand perimeters) measurements were significantly different among the weight groups (p<0.05) and positively correlated with handgrip strength for the whole group. However, only a few measurements – IFL,MFL,P4,P5 – were positively correlated among weight groups. Poor correlations were found between hand-specific variables – TL,IFL,MFL,P4 – and sport achievement. Only P3 was highly correlated with sport achievement and together with FS1 explained 44.4% of its variance. Conclusions: The results indicate that the handgrip strength is mostly dependent on the basic (body height) and hand-specific (IFL, MFL, and P4) anthropometric parameters in judokas. Sport achievement was related to hand perimeter (P3), but its variability was weakly explained and thus hand-specific measurements may not be good predictors for judo performance.

Supination control increases performance in sideward cutting movements in tennis

The objective of this study was to explore the effects of tennis shoe characteristics on performance during sideward cutting movements followed by direction changes. Five tennis players (age = 21.5 ± 0.8 years, mass = 75.2 ± 2.8 kg, and height = 1.78 ± 0.05 m) participated in the study and 10 tennis shoes were tested. Several footwear mechanical parameters were analyzed: Shore A hardness, longitudinal and transverse flexibility, midsole height at heel, presence of heel counters, and weight. A force plate was used to measure the kinetic variables, and two video cameras were used to perform a three-dimensional photogrammetric analysis. Results revealed that subject–footwear interaction was statistically not significant (p>0.05) for the kinetic and kinematic variables. Only contact time (p = 0.008) and supination movement (p = 0.009) were footwear dependent. Positive correlations between contact time and first supination peak (r = 0.783, p = 0.007) and second supination peak (r = 0.730, p = 0.016) were observed. Impulse was not changed, which means shoes limiting supination allowed tennis players to perform faster sideward cutting movements.

The location of the tibial accelerometer does influence impact acceleration parameters during running

ABSTRACT Tibial accelerations have been associated with a number of running injuries. However, studies attaching the tibial accelerometer on the proximal section are as numerous as those attaching the accelerometer on the distal section. This study aimed to investigate whether accelerometer location influences acceleration parameters commonly reported in running literature. To fulfil this purpose, 30 athletes ran at 2.22, 2.78 and 3.33 m · s–1 with three accelerometers attached with double-sided tape and tightened to the participants’ tolerance on the forehead, the proximal section of the tibia and the distal section of the tibia. Time-domain (peak acceleration, shock attenuation) and frequency-domain parameters (peak frequency, peak power, signal magnitude and shock attenuation in both the low and high frequency ranges) were calculated for each of the tibial locations. The distal accelerometer registered greater tibial acceleration peak and shock attenuation compared to the proximal accelerometer. With respect to the frequency-domain analysis, the distal accelerometer provided greater values of all the low-frequency parameters, whereas no difference was observed for the high-frequency parameters. These findings suggest that the location of the tibial accelerometer does influence the acceleration signal parameters, and thus, researchers should carefully consider the location they choose to place the accelerometer so that equivalent comparisons across studies can be made.