Author(s): MAUDRICH, T., DEGENER, S., RAGERT, P., KENVILLE, R., Institution: LEIPZIG UNIVERSITY, FACULTY OF SPORTS SCIENCE, Country: GERMANY, Abstract-ID: 1154

INTRODUCTION:
Blood Flow Restriction Training (BFRT) is an emerging method to stimulate strength and hypertrophy1. In BFRT, arterial inflow and venous outflow in the target muscle is restricted by proximally applying a tourniquet. In this context, it has been shown that the complete deafferentation of the median nerve by ischemic nerve blockade leads to a reduced response of the somatosensory evoked potentials (SEP)2. Arguably, with BFRT, using a proximally applied cuff and consequent attenuated compression of the target limb, similar modulations of SEP components might be observed. This study aimed at investigating the acute effects of BFRT on the excitability of the somatosensory system, by focusing on modulational capacities of SEP.
METHODS:
In total, 12 healthy adults (mean age: 23.0 ± 3.2 yrs) were enrolled in this randomized crossover study consisting of 3 experimental sessions. During each of the experimental sessions, participants underwent one of three conditions: application of blood flow restriction (BFR) without strength training (CUFF), strength training (unilateral biceps curls) without BFR (TRAIN), strength training with BFR (BFRT). One BFR cuff was attached to the upper arm being trained (ACTIVE) to the most proximal region just below the m. deltoideus. The opposite arm (PASSIVE) served as the intraindividual control limb. Bilateral median nerve SEP were applied at the wrist (5 Hz, 300 pulses, 0.2 ms square wave pulse) before, during and after BFR. SEP responses after right median nerve stimulation were recorded peripherally and at the scalp with the following montage according to the international 10-20 system: right Erb’s point – (A1+A2) for N9; C3’ – (A1+A2) for P14; C3’ – Fz for N20. The opposite montage was used for left median nerve stimulation. Amplitudes and latencies of short-latency components (N9, P14, N20) were calculated.
RESULTS:
No differences in SEP amplitudes between conditions could be revealed for ACTIVE or PASSIVE (all p > 0.05). With respect to N9 latencies of ACTIVE, a significant difference between conditions CUFF and TRAIN could be observed (mean difference: 0.26 ms, SE = 0.06 ms, p = 0.001, d = 0.348). No such difference could be observed for PASSIVE.
CONCLUSION:
In conclusion, our study provides evidence for the safety of blood flow restriction training (BFRT) within the somatosensory domain, according to current guidelines for both recreational and rehabilitative purposes. The observed negligible difference in N9 latencies between CUFF and TRAIN may not be of practical significance in healthy adults.

REFERENCES:
1 Patterson, S. D. et al. Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. Front Physiol 10, 533 (2019).
2 Hayashi, R., Ogata, K., Nakazono, H. & Tobimatsu, S. Modified ischaemic nerve block of the forearm: use for the induction of cortical plasticity in distal hand muscles. The Journal of Physiology 597, 3457-3471 (2019).