دانلود رایگان مقاله تغییرات در تحریک پذیری کورتیکواسپاینال تحت سربالایی مقابل ورزش سراشیبی تردمیل

abstract

An acute bout of aerobic exercise induces neuroplasticity in the motor cortex. Moreover, paired associative stimulation (PAS) is known to induce neuroplasticity in M1. However, the possible influence of the type of exercise on the neuroplastic changes remains unknown. The present study investigated the effects of two different modes of muscle contraction produced during locomotor exercise on changes in corticospinal (CS) excitability. Subjects performed two 30-min treadmill exercises at an intensity corresponding to 60% of their maximal heart rate with either a +10% (uphill) or −10% (downhill) slope. These exercises were followed or not by paired associative stimulation method (PAS25) which consisted of 200 paired stimuli (0.25 Hz, 15 min) of median nerve electrical stimulation followed by transcranial magnetic stimulation of the hand M1 area (ISI 25 ms). Motor evoked potentials (MEP), assessed through abductor pollicis brevis (APB) activity were obtained before exercise, at 5 min, 15 min and 30 min after exercise. A significant (P < 0.05) increase of the MEP amplitude was observed 30 min after both exercises but was not different between the two modes of locomotion. On the contrary, MEP amplitude with PAS25 increased only 30 min after downhill exercise. We conclude that sub-maximal treadmill exercise increases CS excitability within a period of 30 min. However, the predominant mode of muscle contraction during uphill versus downhill locomotion does not influence CS excitability when assessed using a non-exercised muscle. However, results from PAS25 suggest that specific neuroplastic changes occur likely due to homeostatic mechanisms induced by exercise plus a PAS protocol.

5. Conclusion

The present study shows that sub-maximal non-fatiguing locomotor exercise on a treadmill affects CS excitability within a delayed period of 30-min when it is tested in a muscle not directly implicated in the exercise. The predominant mode of muscle contraction of the knee extensors during uphill versus downhill locomotor activities does not influence the CS excitability changes. However, it appears that specific neural changes exist in uphill compared to downhill running exercises as highlighted by different responses when exercises were followed by a facilitating PAS25 protocol. The main limitation of this study was that we did not record the M-wave compound in both the exercised (quadriceps) and non-exercised (APB) muscles. Hence, we cannot speculate as to the neuromuscular changes which could have potentially affected changes in MEP. Further studies should focus on the cortical systems targeting by PAS to explain the different CS changes between these two paradigms: exercise alone and exercise + PAS.