Corticomotor Function During Blood Flow Restricted Arm Crank Ergometry

M.L. Frechette; A-M Vallence; B.R. Scott; S.B. Cook

doi:10.1249/01.mss.0000536031.73986.97

Meeting Abstract Low-intensity exercise with blood flow restriction (BFR-LI) may be used as an alternative to high-intensity (HI) exercise. The underlying neurophysiological mechanisms of adaptation remain elusive. PURPOSE: To examine corticomotor and metabolic function during HI and BFR-LI arm ergometry. METHODS: Twelve males (age: 23.9±3.75 yrs, BMI: 25.3±4.26 kg•m-2) completed three 15-minute arm ergometry conditions: HI, low-intensity (LI), and BFR-LI. HI was completed at 60% of maximal power output, while LI and BFR-LI were completed at 30% of maximal power output. In the BFR-LI condition, cuff pressure to the proximal biceps brachii was set to 70% of occlusion pressure. Single-pulse transcranial magnetic stimulation was delivered to the left primary motor cortex to measure motor evoked potentials (MEPs) in the right biceps brachii at baseline, 1, 10, and 15 minutes post-exercise. Blood lactate (BL) was measured at baseline, immediately and 5-minutes post-exercise. Relative VO2 and HR were recorded at 2 minute intervals during the exercise protocol. Each dependent variable was analyzed using within-subject repeated-measures ANOVA to evaluate condition x time interactions. RESULTS: MEP amplitudes throughout exercise were not different between conditions (p = 0.883). A significant main effect of time indicated an overall elevation in all conditions in MEP compared to baseline (0.80±0.51 mV), 10 minutes (1.16±0.74 mV), and 15 minutes (1.04±0.47 mV; p < 0.001). BL following HI was 45% greater (p = 0.03) and 50% greater (p < 0.001) than the BFR-LI and LI conditions, respectively. A similar trend was seen at 5-minutes post-exercise. The HI condition resulted in HR values of (162 bpm±4 bpm) at the completion of exercise. This was higher than LI (117±5 bpm) and BFR-LI (125±5 bpm; p < 0.001). VO2 values were significantly higher with HI (24.0±1.1 ml•kg•min-1) when compared to LI (11.4±1.2ml•kg-1•min-1) and BFR-LI (13.7±0.8ml•kg-1•min-1) (p < 0.001). CONCLUSION: High intensity arm ergometry elicited the highest VO2, HR, and BL values, suggesting greater metabolic demands. Despite higher physical demands, MEP amplitudes increased for all conditions, suggesting similar responses in corticospinal excitability.

Corticomotor Function During Blood Flow Restricted Arm Crank Ergometry

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