Publications by authors named "Haiko B Zimmermann"
The force-length relationship is usually obtained for isometric contractions with maximal activation, but less is known about how sarcomere length affects force during submaximal activation. During submaximal activation, length-dependent alterations in calcium sensitivity, owing to changes in cross-bridge kinetics (rate of attachment and/or detachment), result in an activation-dependent shift in optimal length to longer sarcomere lengths. It is known that sarcomere length, as well as temperature and phosphorylation of the regulatory light chains of myosin, can modify Ca⁺ sensitivity by altering the probability of cross-bridge interaction.
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- The study aimed to assess the reliability of swimming performance tests in both dry-land and water scenarios, and to examine the occurrence of significant differences between limbs in swimmers.
- Twenty-eight swimmers completed various physical tests twice, a week apart, and researchers measured how consistent the results were over time using specific statistical methods.
- Most tests showed good reliability, except for shoulder range of motion, and some athletes had meaningful limb asymmetries, indicating potential areas for improvement in their training.
: The objective of this study was to evaluate a plyometric conditioning activity (3 sets of 5 countermovement jumps, [CA]) for twitch properties and voluntary knee extension. : After a familiarization session, fourteen highly trained sprint athletes, 12 men (23.25 ± 7.
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- Landing is crucial for injury prevention, where equal use of lower limbs helps absorb shock, but fatigue may cause imbalances.
- The study involved 15 active men who performed a fatigue protocol with vertical jumps and assessed lower limb asymmetry through ground reaction force, leg stiffness, and coordination during a landing task.
- Results showed that while fatigue did not significantly impact asymmetry indexes overall, moderate effects were noted on peak ground reaction force and leg stiffness immediately after the fatigue protocol.
Purpose: The objective of this study was to analyze the effects of a conditioning activity (CA) composed of continuous countermovement jumps on twitch torque production and 30-m sprint times.
Methods: A total of 12 sprint athletes, 10 men (23.5 [7.
Does postactivation potentiation (PAP) increase voluntary performance?
Appl Physiol Nutr Metab
April 2020
The transient increase in torque of an electrically evoked twitch following a voluntary contraction is called postactivation potentiation (PAP). Phosphorylation of myosin regulatory light chains is the most accepted mechanism explaining the enhanced electrically evoked twitch torque. While many authors attribute voluntary postactivation performance enhancement (PAPE) to the positive effects of PAP, few actually confirmed that contraction was indeed potentiated using electrical stimulation (twitch response) at the time that PAPE was measured.
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