During running, each contact between the foot and the ground causes an impact. Ground reaction forces (GRF) are considered as an input into the musculoskeletal system. It involves a sudden deceleration in the lower limb packages (including muscles) which generates Soft-Tissue Vibrations (STV). The body is able to attenuate Soft-Tissue Vibrations (STV) but this capability decreases with fatigue. STV could be minimize by improving shoe midsole hardness.
Only 4 studies have studied Soft-Tissue Vibrations (STV) with a distance not exceeding 10 km and without evaluating the potential influence of the shoe. Thus, the effects of shoe midsole hardness on Soft-Tissue Vibrations (STV) and neuromuscular fatigue at the end of an intense and/or long run remains unknown. The purpose is to compare two shoes whose only midsole hardness differs during a half-marathon on Soft-Tissue Vibrations (STV), neuromuscular fatigue and running kinetics. Maybe the shoe ensuring a better STV damping of the medial gastrocnemius muscle would reduce neuromuscular fatigue and improve comfort.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
20
The "hard shoes" runners get on the treadmill for 21 km at a speed corresponding to 70 percent (%) of their the maximum aerobic speed (MAV) and are evaluated.
The "soft shoes" runners get on the treadmill for 21 km at a speed corresponding to 70 percent (%) of their the maximum aerobic speed (MAV) and are evaluated.
Centre Hospitalier Universitaire de Saint-Etienne
Saint-Etienne, France
Change of the damping coefficient (in percent %).
The main evaluation criterion will be the relative variation (in percent %) of the damping coefficient (in /s) of the medial gastrocnemius muscle measured with an accelerometer, at the beginning (the first five minutes) and at the end (the last five minutes) of 21 km at a speed corresponding to 70% of the maximum aerobic speed (MAS) on a treadmill, carried out by experienced amateurs during two shoe conditions: soft and firm sole.
Time frame: From the beginning to the end of the 21 km race.
Temporal evolution of vibrations measurements.
The relative variation (in percent %) of the damping coefficient (in /s) of the medial gastrocnemius muscle will be measured with an accelerometer every 3 km at a speed corresponding to 70% of the maximum aerobic speed (MAS) on a treadmill, carried out by confirmed amateurs during the two shoe conditions. For this outcome, it is not possible to use an unit of time, because the time of the measurements are define only by the distance covered by the subject.
Time frame: Kilometers : 1st, 3rd, 6th, 9th, 12th, 15th, 18th, 21st
Evaluation of improved vibration damping on neuromuscular fatigue : isometric force
The relative change (in percent %) in the maximum isometric force (in Newton) of the ankle plantar flexors before and after the 21 km
Time frame: From the beginning to the end of the 21 km race.
Evaluation of improved vibration damping on neuromuscular fatigue : jerk amplitude.
The relative change (in percent %) in jerk amplitudes measured by electrically evoked force (in Newton) after isometric contraction of the plantar flexors of the ankle, before and after the 21 km.
Time frame: From the beginning to the end of the 21 km race.
Evaluation of improved vibration damping on neuromuscular fatigue : level of voluntary activation.
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The relative change (percent %) in the maximum level of voluntary activation (percent %) measured in isometric mode of the plantar flexors of the ankle before and after the 21 km
Time frame: From the beginning to the end of the 21 km race.
Evaluation of improved vibration damping on neuromuscular fatigue : plantar flexors.
The relative change (in percent %) in the maximum isometric force (in Newton) of the plantar flexors of the toes before and after the 21 km.
Time frame: From the beginning to the end of the 21 km race.
Biomechanical parameters measurement : Ground reaction forces (Newton)
Ground reaction forces (in Newton, measured by treadmill force platforms). For this outcome, it is not possible to use an unit of time, because the time of the measurements are define only by the distance covered by the subject.
Time frame: Kilometers : 1st, 3rd, 6th, 9th, 12th, 15th, 18th, 21st.
Biomechanical parameters measurement : Spatio-temporal parameters (second)
Spatio-temporal parameters: contact time (CT) and flight time (TV) For this outcome, it is not possible to use an unit of time, because the time of the measurements are define only by the distance covered by the subject.
Time frame: Kilometers : 1st, 3rd, 6th, 9th, 12th, 15th, 18th, 21st.
Temporal evolution of the energy cost measurement
This will be the relative variation (in percent %) of the energy cost (in J/kg/m), measured continuously thanks to a portable gas exchange measurement system (ergo spirometer Metamax 3B®, Cortex Medical, Leipzig, Germany), at a speed corresponding to 70% of the maximum aerobic speed (MAS) on a treadmill, carried out by experienced amateurs during the two shoe conditions.
Time frame: From the beginning to the end of the 21 km race.