The purpose of this study was to investigate the effects of LI-BFR on metabolic stress, muscle swelling, skeletal muscle activation, and indices of muscle damage. The second purpose of this study was to validate a practical alternative to BFR. The primary findings of this research were that moderate pBFR resulted in greater indices of metabolic stress, muscle swelling, and muscle activation than did a work-matched control, without increasing indices of muscle damage. In addition, moderate pBFR resulted in venous, but not arterial occlusion in all the participants.
Previous research using a pneumatic cuff has demonstrated that using a 30% 1RM load resulted in similar metabolic stress to high-intensity (65% 1RM) non-BFR resistance exercise (33). However, pneumatic cuffs may not be practical for the majority of the population. For this reason, Loenneke and Pujol (22) suggested the use of knee wraps, which are similar in width to the well-studied KAATSU device. Specifically, these researchers applied knee wraps proximally around participants' thigh until they were snug, but the wraps did not cause pain. However, these researchers did not quantify the tightness of the wrap. Additionally, they did not verify if wrapping resulted in venous and arterial BFR. For this reason, we chose to wrap the participants at a moderate perceived pressure (7/10), and we verified venous but not arterial occlusion in all the participants examined. Low-intensity resistance exercise with moderate LI-pBFR resulted in greater metabolic stress than in the control condition. This metabolic accumulation with LI-BFR is likely produced from the reduction in oxygen from applying the wraps. Mechanistically speaking, metabolic accumulation may increase the recruitment of higher threshold (type II) fibers through the stimulation of group III and IV afferent fibers (37). This increased activation is important for muscle hypertrophy because it is thought that there is a close relationship between increased activation and muscle protein synthesis (20). In addition, that accumulation of metabolites may also facilitate the increase in growth hormone observed after resistance exercise with BFR (34), although the muscle anabolic effect of growth hormone in adults is largely unfounded (29).
Recruitment of higher threshold motor units is important for the stimulation of muscle hypertrophy (7). It is commonly suggested that external load dictates changes in motor unit recruitment (2). However, results from LI-BFR training suggests that intensity determined by external load is of less importance than changes in the intramuscular environment (1). Through the application of blood flow restriction, the intensity of exercise can be increased, without altering the external load (1). Our results indicated that LI-pBFR increased skeletal muscle activation. These findings agreed with those of Yasuda et al. (38) who reported increases in EMG activity with LI-BFR using the KAATSU device and a similar protocol to our own. However, it should be noted that the Yasuda et al. (38) study investigated the elbow flexors. Regardless, the mechanism underlying increased motor unit recruitment is likely tied to the accumulation of metabolites, which can increase muscle fiber recruitment through the stimulation of group III and group IV afferents (37).
Our results suggest that moderate pBFR can acutely increase hypertrophic stimuli such as metabolic stress, skeletal muscle swelling, and EMG determined muscle activation. We also found that a perceived pressure of 7 out of 10 consistently resulted in complete occlusion of the veins, but not arteries. Therefore, the use of pBFR may serve as a less expensive alternative to pneumatic cuffs in resistance trained populations when wrapping at a moderate pressure. Future research should investigate the long-term effects of pBFR on skeletal muscle strength and hypertrophy.
All the authors contributed to the study design, data collection, and article preparation.
1. Abe T, Loenneke JP, Fahs CA, Rossow LM, Thiebaud RS, Bemben MG. Exercise intensity and muscle hypertrophy in blood flow-restricted limbs and non-restricted muscles: a brief review. Clin Physiol Funct Imaging 32: 247–252, 2012.
2. ACSM. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports Exerc 41: 687–708, 2009.
3. Armstrong LE, Whittlesey MJ, Casa DJ, Elliott TA, Kavouras SA, Keith NR, Maresh CM. No effect of 5% hypohydration on running economy of competitive runners at 23 degrees C. Med Sci Sports Exerc 38: 1762–1769, 2006.
4. Baechle TR, Earle RW, and National Strength & Conditioning Association (U.S.). Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics, 2008.
5. Clarkson PM, Hubal MJ. Exercise-induced muscle damage in humans. Am J Phys Med Rehabil 81: S52–S69, 2002.
6. Cook SB, Clark BC, Ploutz-Snyder LL. Effects of exercise load and blood-flow restriction on skeletal muscle function. Med Sci Sports Exerc 39: 1708–1713, 2007.
7. Doessing S, Heinemeier KM, Holm L, Mackey AL, Schjerling P, Rennie M, Smith K, Reitelseder S, Kappelgaard AM, Rasmussen MH, Flyvbjerg A, Kjaer M. Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis. J Physiol 588: 341–351, 2010.
8. Fahs CA, Rossow LM, Seo DI, Loenneke JP, Sherk VD, Kim E, Bemben DA, Bemben MG. Effect of different types of resistance exercise on arterial compliance and calf blood flow. Eur J Appl Physiol 111: 2969–2975, 2011.
9. Fry AC, Kraemer WJ, Van Borselen F, Lynch JM, Triplett NT, Koziris LP, Fleck SJ. Catecholamine responses to short-term high-intensity resistance exercise overtraining. J Appl Physiol 77: 941–946, 1994.
10. Fry CS, Glynn EL, Drummond MJ, Timmerman KL, Fujita S, Abe T, Dhanani S, Volpi E, Rasmussen BB. Blood flow restriction exercise stimulates mTORC1 signaling and muscle protein synthesis in older men. J Appl Physiol 108: 1199–1209, 2010.
11. Fujita S, Abe T, Drummond MJ, Cadenas JG, Dreyer HC, Sato Y, Volpi E, Rasmussen BB. Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis. J Appl Physiol 103: 903–910, 2007.
12. Green S, Salkind N, Akey T. Using SPSS for Windows: Analyzing and Understanding Data. (2nd ed.). Upper Saddle River, NJ: Prentice Hall, 2000.
13. Gundermann DM, Fry CS, Dickinson JM, Walker DK, Timmerman KL, Drummond MJ, Volpi E, Rasmussen BB. Reactive hyperemia is not responsible for stimulating muscle protein synthesis following blood flow restriction exercise. J Appl Physiol 112: 1520–1528, 2012.
14. Haussinger D, Hallbrucker C, vom Dahl S, Lang F, Gerok W. Cell swelling inhibits proteolysis in perfused rat liver. Biochem J 272: 239–242, 1990.
15. Karabulut M, Abe T, Sato Y, Bemben MG. The effects of low-intensity resistance training with vascular restriction on leg muscle strength in older men. Eur J Appl Physiol 108: 147–155, 2010.
16. Loenneke JP, Abe T, Wilson JM, Thiebaud RS, Fahs CA, Rossow LM, Bemben MG. Blood flow restriction: An evidence based progressive model. Acta Physiol Hung 99: 235–250, 2012.
17. Loenneke JP, Balapur A, Thrower AD, Barnes JT, Pujol TJ. The perceptual responses to occluded exercise. Int J Sports Med 32: 181–184, 2011.
18. Loenneke JP, Fahs CA, Rossow LM, Abe T, Bemben MG. The anabolic benefits of venous blood flow restriction training may be induced by muscle cell swelling. Med Hypotheses 78: 151–154, 2012.
19. Loenneke JP, Fahs CA, Thiebaud RS, Rossow LM, Abe T, Ye X, Kim D, Bemben MG. The acute muscle swelling
effects of blood flow restriction. Acta Physiol Hung 99: 400–410, 2012.
20. Loenneke JP, Fahs CA, Wilson JM, Bemben MG. Blood flow restriction: The metabolite/volume threshold theory. Med Hypotheses 77: 748–752, 2011.
21. Loenneke JP, Kearney ML, Thrower AD, Collins S, Pujol TJ. The acute response of practical occlusion
in the knee extensors. J Strength Cond Res 24: 2831–2834, 2010.
22. Loenneke JP, Pujol TJ. The use of occlusion
training to produce muscle hypertrophy. Strength Cond J 31: 77–84, 2009.
23. Loenneke JP, Thiebaud RS, Fahs CA, Rossow LM, Abe T, Bemben MG. Blood flow restriction does not result in prolonged decrements in torque. Eur J Appl Physiol 112: 3445–3446, 2012.
24. Loenneke JP, Thrower AD, Balapur A, Barnes JT, Pujol TJ. Blood flow-restricted walking does not result in an accumulation of metabolites. Clin Physiol Funct Imaging 32: 80–82, 2012.
25. Loenneke JP, Wilson GJ, Wilson JM. A mechanistic approach to blood flow occlusion
. Int J Sports Med 31: 1–4, 2010.
26. Loenneke JP, Wilson JM, Wilson GJ, Pujol TJ, Bemben MG. Potential safety issues with blood flow restriction training. Scand J Med Sci Sports 21: 510–518, 2011.
27. Madarame H, Neya M, Ochi E, Nakazato K, Sato Y, Ishii N. Cross-transfer effects of resistance training with blood flow restriction. Med Sci Sports Exerc 40: 258–263, 2008.
28. Price DD, McGrath PA, Rafii A, Buckingham B. The validation of visual analogue scales as ratio scale measures for chronic and experimental pain. Pain 17: 45–56, 1983.
29. Rennie MJ, Wackerhage H, Spangenburg EE, Booth FW. Control of the size of the human muscle mass. Annu Rev Physiol 66: 799–828, 2004.
30. Rossow LM, Fahs CA, Sherk VD, Seo DI, Bemben DA, Bemben MG. The effect of acute blood-flow-restricted resistance exercise on postexercise blood pressure. Clin Physiol Funct Imaging 31: 429–434, 2011.
31. Schoenfeld BJ. Does exercise-induced muscle damage play a role in skeletal muscle hypertrophy? J Strength Cond Res 26: 1441–1453, 2012.
32. Suga T, Okita K, Morita N, Yokota T, Hirabayashi K, Horiuchi M, Takada S, Omokawa M, Kinugawa S, Tsutsui H. Dose effect on intramuscular metabolic stress during low-intensity resistance exercise with blood flow restriction. J Appl Physiol 108: 1563–1567, 2010.
33. Suga T, Okita K, Morita N, Yokota T, Hirabayashi K, Horiuchi M, Takada S, Takahashi T, Omokawa M, Kinugawa S, Tsutsui H. Intramuscular metabolism during low-intensity resistance exercise with blood flow restriction. J Appl Physiol 106: 1119–1124, 2009.
34. Takarada Y, Nakamura Y, Aruga S, Onda T, Miyazaki S, Ishii N. Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion
. J Appl Physiol 88: 61–65, 2000.
35. Takarada Y, Sato Y, Ishii N. Effects of resistance exercise combined with vascular occlusion
on muscle function in athletes. Eur J Appl Physiol 86: 308–314, 2002.
36. Takarada Y, Tsuruta T, Ishii N. Cooperative effects of exercise and occlusive stimuli on muscular function in low-intensity resistance exercise with moderate vascular occlusion
. Jpn J Physiol 54: 585–592, 2004.
37. Yasuda T, Abe T, Brechue WF, Iida H, Takano H, Meguro K, Kurano M, Fujita S, Nakajima T. Venous blood gas and metabolite response to low-intensity muscle contractions with external limb compression. Metabolism 59: 1510–1519, 2010.
38. Yasuda T, Brechue WF, Fujita T, Shirakawa J, Sato Y, Abe T. Muscle activation
during low-intensity muscle contractions with restricted blood flow. J Sports Sci 27: 479–489, 2009.