College dissertation from Stockholm. Gymnastik och idrottshgskolan, GIH

Abstract: Introduction: Acute enhancements of muscle contractile qualities and gratifaction after a maximal or near maximal conditioning contraction are frequently termed publish activation potentiation (PAP). Although still questionable, PAP is generally associated with enhancements within the myosin regulatory light chain phosphorylation, resulting in enhancements within the excitation–contraction coupling. The PAP seen following a conditioning task frequently coexists with fatigue and may rely on strength level, muscle fiber type and age. Less is famous about how exactly factors for example dynamic and static alterations in muscle length affect PAP, as well as on the relative contribution of contractile and tensile components to PAP.Aim: To boost our knowledge of how, and under what conditions, just one maximal isometric contraction affects plantar flexor muscle contractile performance, along with other muscle tendon qualities, in power athletes.Methods: Supramaximal twitches were evoked via electrical stimulation from the tibial nerve of athletes before as well as on several occasions following a 6-second maximal voluntary isometric contraction (6-s MVIC) both in static muscle, and through passive muscle lengthening and shorting at different angular velocities. Several contractile variables were measured in the twitches. The results of the 6-s MVIC on Calf msucles stiffness was calculated from torque and ultrasonography based measurements of tendon length at two submaximal contraction intensities. Overall stiffness index was calculated by analyzing the passive lengthening torque/position curve.Results: Just one MVIC enhanced muscle contractile qualities and electromechanical delay for approximately a few minutes.

Plantar flexor twitch variables for example peak twitch, rate of torque development and rate of torque relaxation were enhanced during shortening when compared with lengthening muscle actions, as well as in a long when compared with a flexed knee position. Calf msucles stiffness and overall stiffness index weren’t considerably modulated with a single 6-s MVIC.Conclusion: The outcomes of the thesis imply functional enhancements from the 6-s conditioning MVIC would mainly originate from enhancements in contractile instead of tensile components. Stiffness changes ought to be monitored later on PAP-related studies given that they can always occur after more extensive conditioning protocols compared to current one. Enhancements in contractile components subserving muscle strength following a conditioning MVIC shows that enhancements in muscle power following a conditioning task ought to be finest in fast concentric muscle actions, though still contained in muscle lengthening. Conditioning ought to be performed ready where full activation is simple to attain and tailored to mach a sports athlete or number of athlete’s current status and characteristics, maximizing performance inside a specific sport event.

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