Effect of a five-toed minimal protection shoe on static and dynamic ankle position sense.

AIM: The main aim of this study was to test the hypothesis that the VibramFivefingers model, with its minimal structure, cushioning and finger separation, allows a more accurate estimate of static and dynamic foot position compared to wearing a standard cushioned running shoe. METHODS: Static ankle joint position sense was assessed in the sagittal and frontal plane by asking fourteen healthy experienced amateur runners to estimate the perceived direction and amplitude of a support slope surface board placed under their right foot while standing. The dynamic measures were performed with the subjects running on a treadmill at 12 km/h and asking them to evaluate the treadmill surface slope. Two footwear (Fivefingers and a cushioned protective running shoe) and the barefoot condition were compared. RESULTS: Plantarflexion, dorsiflexion, eversion and inversion movements were underestimated in all the experimental conditions. In the static trials there was significantly more angle error underestimation (P<0.05) with the running shoe, while no significant differences were found between Fivefingers and barefoot condition. While running, the treadmill surface slope was significantly better estimated with Fivefingers than in the other two conditions (P<0.05). CONCLUSION: The data support the assumption that with Fivefingers is more likely to get a more correct estimation of the surface slope while standing and running compared to using a standard cushioned running shoe. The finding that the cushioned shoes significantly impair foot position awareness compared to less structured shoes is consistent with the results of some previous studies on healthy and unhealthy subjects.

Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners.

AIM: The first aim of this study was to assess how changes in the mechanical characteristics of the foot/shoe-ground interface affect spatio-temporal variables, ground pressure distribution, sagittal plane kinematics, and running economy in 8 experienced barefoot runners. The second aim was to assess if a special lightweight shoe (Vibram Fivefingers) was effective in mimic the experience of barefoot running. METHODS: By using an instrumented treadmill, barefoot running, running with the Fivefingers, and running with standard running shoe were compared, analyzing a large numbers of consecutive steps. Foot/shoe-ground interface pressure distribution, lower limb kinematics, V.O(2) and heart rate data were simultaneously collected. RESULTS: Compared to the standard shod condition when running barefoot the athletes landed in more plantarflexion at the ankle. This caused reduced impact forces and changes in stride kinematics. In particular, significantly shorter stride length and contact times and higher stride frequency were observed (P<0.05). Compared to standard shod condition, V.O(2) and peak impact forces were significantly lower with Fivefingers (P<0.05) and much closer to barefoot running. Lower limb kinematics with Fivefingers was similar to barefoot running with a foot position which was significantly more plantarflexed than in control shoe (P<0.05). CONCLUSIONS: The data of this study support the assumption that changes in the foot-ground interface led to changes in running pattern in a group of experienced barefoot runners. The Fivefingers model seems to be effective in imitating the barefoot conditions while providing a small amount of protection.

Pulmonary gas exchange in athletes with exercise-induced hypoxaemia.

Hypoxaemia that is induced by physical exercise (EIH) in some athletes, who are however capable of enduring intense muscolar work, is a phenomenon that has been known for some time. However, assumptions such as alveolar hypoventilation, veno-arterial shunt, limitation of diffusion, or mismarch of the VA/Q ratio, have not to date been able to exhaustively explain this phenomenon. In this study five athletes displaying exercise-induced hypoxaemia were evaluated by increasing-load exercise tests, as proposed by other authors, and by means of intermittent tests with supermaximal exercise steps (130% VO2 max) with breaks for incomplete recovery (3 min). The fundamental fact arising from our study is that the intermittent tests did not bring about hypoxaemia in the tests subjects. Analysis of the ventilator and metabolic parameters, of the alveolar pressure of the O2, and of the partial pressures of the CO2 in the arterial blood, all measured during the two different types of muscular exercise, lead to the belief that the different distribution of the pulmonary blood flow, which has been documented in highly trained athletes, plays a very important role in inducing EIH.