The Proximal and Distal Effects of Blood Flow Restriction Therapy on Upper and Lower Extremity Strengthening: A Randomized Controlled Trial

Abstract

Objectives:

Blood flow restriction (BFR) therapy consists of low-intensity exercise performed under reduced venous return due to an inflatable tourniquet. This produces similar physiologic and clinical effects to high-intensity routines with less joint and tissue stress. Postoperative patients may benefit from more efficient rehabilitation. Proximal and distal effects of BFR have been evaluated, however, minimal literature exists on its use in orthopaedic conditions. The purpose of this study was to determine the effects of low-intensity BFR therapy both proximal and distal, in the upper and lower extremities.

Methods:

This was a prospective, randomized controlled trial of healthy subjects completing a standardized 6-week course of BFR therapy. Subjects were randomized to BFR therapy on one extremity or to a control group. Subjects were excluded for cardiac, pulmonary, or hematologic disease, pregnancy, or previous surgery in the extremity. Data collected at baseline and completion included: limb circumferences, isokinetic, and manual strength testing.

Results:

Forty subjects completed the protocol. Average age was 27.7 years; 54% were female. For both upper and lower extremity groups, a statistically significant increase was observed in manual and isokinetic strength both proximal and distal to the BFR tourniquet when compared to both the non-tourniquet extremity and the control group (p<0.05). Limb circumference significantly increased in the upper (p<0.01) and lower extremities (p=0.02). A significant increase in manual strength was noted in shoulder abduction and scaption, and hip extension and abduction even in the non-tourniquet BFR extremity compared to the control group (p<0.05).

Conclusion:

Low-intensity BFR therapy led to greater increases in muscle strength and hypertrophy. Similar strengthening effects were seen in proximal and distal muscle groups. Strength increases in the contralateral BFR extremity may corroborate a systemic effect. This study provides data to further evaluate the efficacy and safety of BFR therapy in operative and non-operative orthopaedic conditions.

The mean percent increase and comparison between the BFR tourniquet limb and control group with p-values.

LOWER EXTREMITY	Controln=20	BFR limbn=16	p	UPPER EXTREMITY	Controln=20	BFR Limbn=14	p
Circumference				Circumference
Thigh	0.8	3.5	<0.001	Arm	2.5	5.2	<0.001
Leg	0.4	2.8	0.001	Forearm	1.4	4.2	<0.001
Strength				Strength
Knee extension				Shoulder IR
Total work	6	15	0.046	Total work	0.1	12	0.043
Peak torque	3	11	0.018	Peak torque	7	16	0.018
Power	4	12	0.015	Avg Power	2	20	0.078
Knee flexion				Shoulder ER
Total work	14	27	0.044	Total work	12	15	0.389
Peak torque	5	11	0.173	Peak torque	2	10	0.041
Power	7	13	0.135	Avg Power	15	24	0.188
Hip abduction	27	46	0.021	Shoulder Scaption	18	48	0.021
Hip extension	42	60	0.046	Shoulder Flexion	16	39	0.001
Plantar flexion	18	33	0.018	Shoulder Abd	8	33	0.001
Heel raises	4	28	<0.001	Elbow Flexion	29	52	0.047
				Elbow Extension	35	43	0.242
				Grip Strength	0.4	9	0.002