Hemodynamic responses and energy expenditure during blood flow restriction exercise in obese population

Acute effects of blood flow restricted aerobic exercise in type 2 diabetes mellitus

BACKGROUND

This study aimed to compare the acute effects of aerobic exercise performed with blood flow restriction (BFR), a novel method to increase exercise gains, with blood free flow (BFF) conditions in type 2 diabetes mellitus (T2DM).

METHODS

Fifteen individuals with T2DM performed BFF and BFR (40% of arterial occlusion pressure) cycling exercises 48 hours apart, at equal intensity (45% heart rate reserve) and duration (38 minutes). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), blood glucose, heart rate, and muscle oxygen saturation (SmO2) were assessed before-after and during exercise sessions.

RESULTS

SBP, DBP, and MAP in the overload phase were higher in the BFR group than in the BFF group (P = .009, 0.031, and 0.013, respectively). Changes in blood pressure (∆SBP and ∆DBP) were similar between the BFF and BFR groups (P > .05), whereas ∆MAP differed (P = .016). Changes in blood glucose levels and heart rates were not significantly different between the groups. Although SmO2baseline was lower in the BFR group (P = .049), SmO2min and SmO2max did not differ significantly between the BFF and BFR groups.

CONCLUSION

The similar decrease in blood glucose levels between the groups suggests that BFR exercise is favorable in terms of hypoglycemia. The higher blood pressure observed during the BFR exercise remained within safe limits. These results suggest that people with T2DM can safely perform BFR aerobic exercises; however, further studies are required.

Blood flow restriction as a potential therapy to restore physical function following COVID-19 infection

Accumulating evidence indicates that some COVID-19 survivors display reduced muscle mass, muscle strength, and aerobic capacity, which contribute to impairments in physical function that can persist for months after the acute phase of illness. Accordingly, strategies to restore muscle mass, muscle strength, and aerobic capacity following infection are critical to mitigate the long-term consequences of COVID-19. Blood flow restriction (BFR), which involves the application of mechanical compression to the limbs, presents a promising therapy that could be utilized throughout different phases of COVID-19 illness. Specifically, we hypothesize that: 1) use of passive BFR modalities can mitigate losses of muscle mass and muscle strength that occur during acute infection and 2) exercise with BFR can serve as an effective alternative to high-intensity exercise without BFR for regaining muscle mass, muscle strength, and aerobic capacity during convalescence. The various applications of BFR may also serve as a targeted therapy to address the underlying pathophysiology of COVID-19 and provide benefits to the musculoskeletal system as well as other organ systems affected by the disease. Consequently, we present a theoretical framework with which BFR could be implemented throughout the progression from acute illness to outpatient rehabilitation with the goal of improving short- and long-term outcomes in COVID-19 survivors. We envision that this paper will encourage discussion and consideration among researchers and clinicians of the potential therapeutic benefits of BFR to treat not only COVID-19 but similar pathologies and cases of acute critical illness.

Acute Responses to Cycling Exercise With Blood Flow Restriction During Various Intensities

ABSTRACT

Lauver, JD, Moran, A, Guilkey, JP, Johnson, KE, Zanchi, NE, and Rotarius, TR. Acute responses to cycling exercise with blood flow restriction during various intensities. J Strength Cond Res 36(12): 3366-3373, 2022-The purpose of this study was to investigate the acute physiological responses during cycling at various intensities with blood flow restriction (BFR). Subjects ( N = 9; V̇ o2 peak = 36.09 ± 5.80 ml·kg -1 ·min -1 ) performed 5 protocols: high-intensity (HIGH), control (CON-90), 90% of ventilatory threshold (VT) work rate with BFR (90-BFR), 70% of VT with BFR (70-BFR), and 30% V̇ o2 peak with BFR (30-BFR). Protocols consisted of five 2-minute work intervals interspersed with 1-minute recovery intervals. Blood flow restriction pressure was 80% of limb occlusion pressure. V̇ o2 , muscle excitation, tissue oxygen saturation (StO 2 ), discomfort, and level of perceived exertion (RPE) were assessed. Muscle excitation was higher during HIGH (302.9 ± 159.9 %BSL [baseline]) compared with 70-BFR (99.7 ± 76.4 %BSL) and 30-BFR (98.2 ± 70.5 %BSL). StO 2 was greater during 90-BFR (40.7 ± 12.5 ∆BSL), 70-BFR (34.4 ± 15.2 ∆BSL), and 30-BFR (31.9 ± 18.7 ∆BSL) compared with CON-90 (4.4 ± 11.5 ∆BSL). 90-BFR (39.6 ± 12.0 ∆BSL) resulted in a greater StO 2 -Avg compared with HIGH (20.5 ± 13.8 ∆BSL). Also, HIGH (23.68 ± 5.31 ml·kg -1 ·min -1 ) resulted in a greater V̇ o2 compared with 30-BFR (15.43 ± 3.19 ml·kg -1 ·min -1 ), 70-BFR (16.65 ± 3.26 ml·kg -1 ·min -1 ), and 90-BFR (18.28 ± 3.89 ml·kg -1 ·min -1 ); 90-BFR (intervals: 4 = 15.9 ± 2.3; intervals: 5 = 16.4 ± 2.5) resulted in a greater RPE compared with 30-BFR (intervals: 4 = 13.3 ± 1.4; intervals: 5 = 13.7 ± 1.7) during intervals 4 and 5. These results suggest that when adding BFR to various intensities of aerobic exercise, consideration should be given to peak work and VT to provide a balance between high local physiological stress and perceptual responses.

Aerobic exercise with blood flow restriction: energy expenditure, excess post-exercise oxygen consumption, and respiratory exchange ratio

We compared the effects of aerobic exercise with and without blood flow restriction (BFR) to high-intensity aerobic exercise on energy expenditure (EE), excess post-exercise oxygen consumption (EPOC), and respiratory exchange ratio (RER) during and after exercise. Twenty-two recreationally active males randomly completed the following experimental conditions: AE - aerobic exercise without BFR, AE+BFR - aerobic exercise with BFR, HIAE - high-intensity aerobic exercise, CON - non-exercise control condition. EE was significantly (p<0.05) greater during exercise for HIAE compared to all conditions, and for AE+BFR compared to AE and CON during and post-exercise exercise. There were no significant (p>0.05) differences in EPOC between HIAE and AE+BFR at any time point, however, both conditions were significantly (p < 0.05) greater than the AE (d = 1.50 and d = 1.03, respectively) and CON at the first 10 minutes post-exercise. RER during exercise for HIAE was significantly (p<0.05) greater than AE+BFR at the first 6 minutes of exercise (p = 0.003, d = 0.88), however, no significant differences were observed from 9 min up to the end of the exercise. HIAE was also significantly (p<0.05) greater than AE and CON at all time points during exercise, whereas, AE+BFR was significantly (p<0.05) greater than CON at all time points but not significantly (p < 0.05) different than AE (p<0.05); although the overall session RER was significantly (p<0.05) greater during AE+BFR than AE. Altogether, continuous AE+BFR results in greater EE compared to volume matched AE, as well as a similar EPOC compared to HIAE. This article is protected by copyright. All rights reserved.

Physiological and Perceptual Responses to Aerobic Exercise With and Without Blood Flow Restriction

ABSTRACT

Silva, JCG, Domingos-Gomes, JR, Freitas, EDS, Neto, GR, Aniceto, RR, Bemben, MG, Lima-dos-Santos, A, and Cirilo-Sousa, MS. Physiological and perceptual responses to aerobic exercise with and without blood flow restriction. J Strength Cond Res 35(9): 2479-2485, 2021-Although previous studies have demonstrated the potential benefits of aerobic exercise (AE) with blood flow restriction (BFR), these findings have been limited by the approaches used to determine the occlusive pressure. In addition, the physiological and perceptual responses of AE with BFR compared to high-intensity interval exercise (HIIE) remain unclear. Thus, we investigated the physiological and perceptual responses to AE with and without BFR, and HIIE. Twenty-two men were randomly assigned to 4 experimental conditions: AE (40% of maximal oxygen consumption [V˙o2peak]), AE with 50% of BFR (AE-BFR: 40% VV˙o2peak), HIIE (80% V˙o2peak), and a no exercise control condition (CON: 50% of BFR). Each exercise bout lasted 18 minutes, during which oxygen consumption (V˙o2), heart rate (HR), and ratings of perceived exertion (RPE) were measured at rest and at every 3 minutes during exercise. Ratings of discomfort before and after each trial. The HIIE condition induced the greatest increases in V˙o2 and HR (p < 0.05), whereas AE-BFR was significantly (p < 0.05) greater than AE and CON. HIIE and AE-BFR also elicited the greatest (p < 0.05), but similar (p > 0.05), increases in RPE during exercise, although AE-BFR was significantly greater than HIIE immediately after exercise (p < 0.05). AE-BFR and HIIE also induced similar levels of discomfort after exercise (p > 0.05). In conclusion, HIIE induced the greatest increases in V˙o2 and HR, although the perceptual responses were essentially the same compared with AE-BFR. However, albeit inferior to HIIE, V˙o2 was greater during AE-BFR compared with AE, indicating that this training method may be used to replace HIIE and still significantly elevate V˙o2.

The Systemic Effects of Blood Flow Restriction Training: A Systematic Review

BACKGROUND

Blood flow restriction (BFR) training has been reported to have significant benefits on local skeletal muscle including increasing local muscle mass, strength, and endurance while exercising with lower resistance. As a result, patients unable to perform traditional resistance training may benefit from this technique. However, it is unclear what effects BFR may have on other body systems, such as the cardiovascular and pulmonary systems. It is important to explore the systemic effects of BFR training to ensure it is safe for use in physical therapy.

PURPOSE

The purpose of this study was to systematically review the systemic effects of blood flow restriction training when combined with exercise intervention.

STUDY DESIGN

Systematic review.

METHODS

Three literature searches were performed: June 2019, September 2019, and January 2020; using MedLine, ScienceDirect, PubMed, Cochrane Reviews and CINAHL Complete. Inclusion criteria included: at least one outcome measure addressing a cardiovascular, endocrinological, systemic or proximal musculoskeletal, or psychosocial outcome, use of clinically available blood flow restriction equipment, use of either resistance or aerobic training in combination with BFR, and use of quantitative measures. Exclusion criteria for articles included only measuring local or distal musculoskeletal changes due to BFR training, examining only passive BFR or ischemic preconditioning, articles not originating from a scholarly peer-reviewed journal, CEBM level of evidence less than two, or PEDro score less than four. Articles included in this review were analyzed with the CEBM levels of evidence hierarchy and PEDro scale.

RESULTS

Thirty-five articles were included in the review. PEDro scores ranged between 4 and 8, and had CEBM levels of evidence of 1 and 2. Common systems studied included cardiovascular, musculoskeletal, endocrine, and psychosocial. This review found positive or neutral effects of blood flow restriction training on cardiovascular, endocrinological, musculoskeletal, and psychosocial outcomes.

CONCLUSIONS

Although BFR prescription parameters and exercise interventions varied, the majority of included articles reported BFR training to produce favorable or non-detrimental effects to the cardiovascular, endocrine, and musculoskeletal systems. This review also found mixed effects on psychosocial outcomes when using BFR. Additionally, this review found no detrimental outcomes directly attributed to blood flow restriction training on the test subjects or outcomes tested. Thus, BFR training may be an effective intervention for patient populations that are unable to perform traditional exercise training with positive effects other than traditional distal muscle hypertrophy and strength and without significant drawbacks to the individual.

LEVEL OF EVIDENCE

1b.

The impact of low-intensity blood flow restriction endurance training on aerobic capacity, hemodynamics, and arterial stiffness

BACKGROUND

The aim of this study was to determine the effects of short-term low-intensity blood flow restriction (BFR) endurance training (ET) programs on measures of aerobic capacity, hemodynamics, and arterial stiffness in healthy young males.

METHODS

Thirty-nine healthy young recreationally active males participated in this short-term training study. They were randomly assigned to a high-intensity (HI; N.=11; trained at 60-70% of VO<inf>2</inf> reserve [VO<inf>2</inf>R]), low-intensity (LI; N.=8; trained at 30-40% of VO<inf>2</inf>R), low-intensity with BFR (LI-BFR; N.=10; trained at 30-40% of VO<inf>2</inf>R with BFR) or a non-exercising control group (N.=10). The exercising subjects completed a 6-wk training protocol on a treadmill. Assessment of aerobic capacity (VO<inf>2max</inf>), hemodynamics and arterial stiffness were done before and after training.

RESULTS

Statistical analyses revealed a significant condition main effect (P<0.05) for VO<inf>2max</inf>, indicating significant increase (P<0.05) in VO<inf>2max</inf> in LI-BFR group compared to control. There were no significant changes for resting heart rate (RHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), carotid-radial pulse wave velocity (PWV), and carotid-femoral PWV (P>0.05). However, femoral-tibial PWV decreased significantly (P<0.05) from baseline to post-training.

CONCLUSIONS

The results indicate that the application of BFR during ET may cause faster and/or greater adaptations in one or more physiological systems resulting in improved cardiorespiratory fitness.

Acute and Chronic Responses of Aerobic Exercise With Blood Flow Restriction: A Systematic Review

This study systematically reviewed the available scientific evidence pertaining to the acute and chronic changes promoted by aerobic exercise (AE) combined with blood flow restriction (BFR) on neuromuscular, metabolic and hemodynamic variables. PubMed, Web of Science^TM and Scopus databases were searched for the period from January 2000 to June 2019 and the analysis involved a critical content review. A total of 313 articles were identified, of which 271 were excluded and 35 satisfied the inclusion criteria. Twelve studies evaluated the acute effects and eight studies evaluated the chronic metabolic effects of AE + BFR. For the neuromuscular variables, three studies analyzed the acute effects of AE + BFR and nine studies analyzed the chronic effects. Only 15 studies were identified that evaluated the hemodynamic acute effects of AE + BFR. The analysis provided evidence that AE combined with BFR promotes positive acute and chronic changes in neuromuscular and metabolic variables, a greater elevation in hemodynamic variables than exercise alone, and a higher energy demand during and after exercise. Since these alterations were all well-tolerated, this method can be considered to be safe and feasible for populations of athletes, healthy young, obese, and elderly individuals.

Anaerobic metabolism induces greater total energy expenditure during exercise with blood flow restriction

PURPOSE

We investigated the energy system contributions and total energy expenditure during low intensity endurance exercise associated with blood flow restriction (LIE-BFR) and without blood flow restriction (LIE).

METHODS

Twelve males participated in a contra-balanced, cross-over design in which subjects completed a bout of low-intensity endurance exercise (30min cycling at 40% of [Formula: see text]) with or without BFR, separated by at least 72 hours of recovery. Blood lactate accumulation and oxygen uptake during and after exercise were used to estimate the anaerobic lactic metabolism, aerobic metabolism, and anaerobic alactic metabolism contributions, respectively.

RESULTS

There were significant increases in the anaerobic lactic metabolism (P = 0.008), aerobic metabolism (P = 0.020), and total energy expenditure (P = 0.008) in the LIE-BFR. No significant differences between conditions for the anaerobic alactic metabolism were found (P = 0.582). Plasma lactate concentration was significantly higher in the LIE-BFR at 15min and peak post-exercise (all P≤0.008). Heart rate was significantly higher in the LIE-BFR at 10, 15, 20, 25, and 30min during exercise, and 5, 10, and 15min after exercise (all P≤0.03). Ventilation was significantly higher in the LIE-BFR at 10, 15, and 20min during exercise (all P≤0.003).

CONCLUSION

Low-intensity endurance exercise performed with blood flow restriction increases the anaerobic lactic and aerobic metabolisms, total energy expenditure, and cardiorespiratory responses.

Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics

The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual’s submaximal level, understanding influence of obesity on submaximal work is critical.