• Trine Øhlenschlæger
  • Mathias Mondrup Pedersen
4. semester, Sports Science, Master (Master Programme)
Ischemic preconditioning (IPC) refers to a technique that includes brief rounds of ischemia and reperfusion and which has recently emerged as an intervention to improve muscle activity. IPC can be applied either locally to the tissue of interest (LIPC) or on the tissue of a remote limb (RIPC). The underlying mechanisms of IPC are still not fully understood, but it is suggested that IPC inhibits the ischemia sensitive group III/IV muscle afferents, which leads to an increase of the excitability of the spinal motor neurons. The effects from IPC on motor unit properties has only been investigated in chronic stroke survivors, and the study showed that LIPC increased muscle strength through improved muscle activation.
The objective for the present study proposal is to investigate if IPC has an effect on the discharge rate and recruitment threshold for motor units in healthy adults when performing a submaximal isometric muscle contraction. An additional objective is to investigate whether the effect of LIPC and RIPC respectively differ.
It is hypothesized that LIPC increases the discharge rate and decreases the recruitment threshold for the motor units to a larger extent than RIPC, and that both of these interventions will lead to a higher discharge rate and lower recruitment threshold of the motor units compared to a sham intervention.
The proposed study will be carried out as a randomized counterbalanced crossover study with a required sample size of 16 healthy adults. During the proposed study, subjects will undergo three interventions: LIPC, RIPC and sham. Each intervention will consist of four cycles of 5x5 min occlusion/reperfusion, with a pressure of 225 mmHg for both LIPC and RIPC, and 25 mmHg for sham. Before and after each intervention, the subjects will perform three maximal voluntary contractions (MVC) and two submaximal isometric ramp contractions at 40% MVC with the dorsiflexors. During the experimental protocol, measurements of central motor drive (motor unit discharge rate and recruitment threshold) from the right tibialis anterior muscle will be conducted using high-density surface electromyography.
Carrying out the study in practice can contribute with a unique perspective on the central motor drive after an IPC intervention and knowledge of the possible effects on motor unit properties.
Publication date2 Jun 2020
Number of pages58
ID: 333385979