Lanza2019_Article_ExplosiveStrengthEffectOfKnee-.pdf (930.1 kB)
Explosive strength: effect of knee-joint angle on functional, neural, and intrinsic contractile properties
journal contribution
posted on 2019-06-03, 09:47 authored by Marcel Bahia Lanza, Tom BalshawTom Balshaw, Jonathan FollandJonathan FollandPURPOSE: The present study compared knee extension explosive isometric torque, neuromuscular activation, and intrinsic contractile properties at five different knee-joint angles (35°, 50°, 65°, 80°, and 95°; 0° = full knee extension). METHODS: Twenty-eight young healthy males performed two experimental sessions each involving: 2 maximum, and 6-8 explosive voluntary contractions at each angle; to measure maximum voluntary torque (MVT), explosive voluntary torque (EVT; 50-150 ms after contraction onset) and quadriceps surface EMG (QEMG, 0-50, 0-100, and 0-150 ms after EMG onset during the explosive contractions). Maximum twitch and M-wave (MMAX) responses as well as octet contractions were evoked with femoral nerve stimulation at each angle. RESULTS: Absolute MVT and EVT showed an inverted 'U' relationship with higher torque at intermediate angles. There were no differences between knee-joint angles for relative EVT (%MVT) during the early phase (≤ 75 ms) of contraction and only subtle differences during the late phase (≥ 75 ms) of contraction (≤ 11%). Neuromuscular activation during explosive contractions was greater at more flexed than extended positions, and this was also the case during MVT. Whilst relative twitch torque (%MVT) was higher at knee flexed positions (P ≤ 0.001), relative octet torque (%MVT) was higher at knee extended positions (P ≤ 0.001). CONCLUSION: Relative EVT was broadly similar between joint angles, likely because neuromuscular activation during both explosive and plateau (maximum) phases of contraction changed proportionally, and due to the opposing changes in twitch and octet evoked responses with joint angle.
History
School
- Sport, Exercise and Health Sciences
Published in
European Journal of Applied PhysiologyVolume
119Issue
8Pages
1735–1746Citation
LANZA, M.B., BALSHAW, T.G. and FOLLAND, J.P., 2019. Explosive strength: effect of knee-joint angle on functional, neural, and intrinsic contractile properties. European Journal of Applied Physiology, 119 (8), pp.1735–1746.Publisher
Springer (© the authors)Version
- VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/Acceptance date
2019-05-13Publication date
2019-05-21Notes
This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/eISSN
1439-6327Publisher version
Language
- en