Adaptation of Perceptual Responses to Low-Load Blood Flow Restriction Training

Abstract

Martín-Hernández, J, Ruiz-Aguado, J, Herrero, AJ, Loenneke, JP, Aagaard, P, Cristi-Montero, C, Menéndez, H, and Marín, PJ. Adaptation of perceptual responses to low-load blood flow restriction training. J Strength Cond Res 31(3): 765-772, 2017-The purpose of this study was to determine the adaptive response of ratings of perceived exertion (RPE) and pain over 6 consecutive training sessions. Thirty subjects were assigned to either a blood flow restriction training (BFRT) group or a high-intensity resistance training (HIT) group. Blood flow-restricted training group performed 4 sets (30 + 15 + 15 + 15, respectively) of unilateral leg extension at an intensity of 20% one repetition maximum (1RM) while a restrictive cuff was applied to the most proximal part of the leg. The HIT group performed 3 sets of 8 repetitions with 85% 1RM. Ratings of perceived exertion and pain were assessed immediately after each exercise set along the 6 training sessions and were then averaged to obtain the overall RPE and pain per session. Statistical analyses showed significant main effects for group (p ≤ 0.05) and time (p < 0.001). Ratings of perceived exertion values dropped from session 1 to session 6 in both BFRT (8.12 ± 1.3 to 5.7 ± 1.1, p < 0.001) and HIT (8.5 ± 1.2 to 6.40 ± 1.2, p < 0.001). Similar results were observed regarding pain ratings (BFRT: 8.12 ± 1.3 to 5.90 ± 1.55, p < 0.001; HIT: 6.22 ± 1.7 to 5.14 ± 1.42, p < 0.01). Our results indicate that RPE was higher after HIT, whereas differences did not reach significance regarding pain. These perceptual responses were attenuated over time, and the time course of this adaptive response was similar between BFRT and HIT. In summary, BFRT induces a marked perceptual response to training, comparable with that observed with HIT. However, this response becomes attenuated with continuous practice, leading to moderate values of RPE and pain. Perceptual responses may not limit the application of BFRT to highly motivated individuals.

Interface pressure, perceptual, and mean arterial pressure responses to different blood flow restriction systems

“…When implementing tourniquet occlusion clinically, patients should be monitored continuously for pain and hypertension 8 which may dictate work volume and patient adherence. 25 In the present study, pain was significantly higher in the RI and HS systems compared to the PT system in sets 3 and 4, when cuffs were set at the same relative pressure of 80% LOP. The RI and HS systems were found to elicit pressures that were 9-11 mm Hg and 37-62 mm Hg higher than the set pressure, respectively, which may contribute to the exacerbated pain response in the load and repetition-matched conditions.…”

“…When implementing tourniquet occlusion clinically, patients should be monitored continuously for pain and hypertension which may dictate work volume and patient adherence . In the present study, pain was significantly higher in the RI and HS systems compared to the PT system in sets 3 and 4, when cuffs were set at the same relative pressure of 80% LOP.…”

“…It should be acknowledged that these ratings are not particularly high, and that perceptual responses to light load (30% 1RM) BFR exercise are lower compared to an equivalent form of exercise at heavier loads (70%1RM) . Together with demonstration of a similar time course of adaptation to perceptual responses between light load BFR and heavy load exercise, this supports the feasibility of BFR as a clinical rehabilitation tool.…”

“…Interface pressure between the cuff and the limb in different BFR systems, and the influence on perceptual and MAP responses, has not been examined to date. It is important to examine interface pressure during passive BFR and dynamic BFR exercise as excessive pressures may increase the risk of tourniquet‐induced injury, and may also influence perceptual and MAP responses to BFR exercise which in turn may influence exercise tolerance and adherence to a clinical BFR rehabilitation program . In this study, we examined the interface pressure during passive BFR and BFR exercise in three different BFR systems commonly used in the literature.…”

“…It is important to examine interface pressure during passive BFR and dynamic BFR exercise as excessive pressures may increase the risk of tourniquet-induced injury, 8,9 and may also influence perceptual and MAP responses to BFR exercise which in turn may influence exercise tolerance and adherence to a clinical BFR rehabilitation program. 25 In this study, we examined the interface pressure during passive BFR and BFR exercise in three different BFR systems commonly used in the literature. Interface pressure appears to be lower than the set pressure in all systems when BFR is applied passively, which we hypothesize may be a result of pressure control and cuff properties within the BFR systems.…”