What's The Science Behind It?

BFR is applied during both voluntary resistance exercise (BFR-RE) and aerobic exercise (BFR-AE), and also passively without exercise (P-BFR).

Protocols for Enhanced Muscle Strength and Hypertrophy
In the following section, an overview of the BFR literature aiming at increasing maximal skeletal muscle strength and muscle mass will be provided. Tables 1, 2 provide an overview of the recommendations for the application of BFR-RE and BFR-AE, respectively.
BFR-RE
Increases in muscle hypertrophy and strength with BFR-RE are extensively documented. In recent years, a number of systematic reviews and meta-analyses have demonstrated BFR-RE to effectively increase skeletal muscle strength and/or hypertrophy in healthy young (Loenneke et al., 2012d; Slysz et al., 2016; Lixandrão et al., 2018) and older (Centner et al., 2018a; Lixandrão et al., 2018) populations, as well as load compromised populations in need of rehabilitation (Hughes et al., 2017). Various measures of muscle strength have been shown to improve in response to BFR-RE interventions, including dynamic isotonic (Burgomaster et al., 2003; Moore et al., 2004), isometric (Takarada et al., 2000a; Moore et al., 2004) and isokinetic strength (Takarada et al., 2000c, 2004 Burgomaster et al., 2003; Moore et al., 2004), as well as rate of force development/explosive strength capacity (Nielsen et al., 2017b). It is well documented that muscle hypertrophy and strength adaptations with BFR-RE are significantly greater than those achieved with low-load resistance exercise (LL-RE) alone in most (Takarada et al., 2002, 2004; Abe et al., 2005a,b,c; Yasuda et al., 2005) but not all studies (Farup et al., 2015). Such adaptations have been observed after only 1–3 weeks (Abe et al., 2005a,b, 2006; Fujita et al., 2008; Nielsen et al., 2012; Yasuda et al., 2005). These timescales for early increases in strength are mirrored in high-load resistance exercise (HL-RE) research (Blazevich et al., 2017), however, this is not typically the case for muscle mass where adaptations are not usually observed in 1–3 weeks following HL-RE (Damas et al., 2016).



TABLE 1 | Model of exercise prescription with BFR-RE. Guidelines
Frequency
Load Restriction time
Type
Sets
Cuff
Repetitions Pressure
Rest between sets Restriction form Execution speed Execution
2–3 times a week (>3 weeks) or 1–2 times per day (1–3 weeks)
20–40% 1RM
5–10 min per exercise (reperfusion between exercises)
Small and large muscle groups (arms and legs/uni or bilateral)
2–4
5 (small), 10 or 12 (medium), 17 or 18 cm (large) (75reps)–30×15×15×15,orsetstofailure 40–80% AOP
30–60 s
Continuous or intermittent
1–2 s (concentric and eccentric)
Until concentric failure or when planned rep scheme is completed
Frontiers in Physiology | www.frontiersin.org 2
May 2019 | Volume 10 | Article 533

 

Exercise Load, Volume, Rest Periods, Duration, and Frequency
Exercise Load
The pressure applied during exercise may also be dictated to some degree by the relative load lifted during resistance exercise. For the majority of individuals exercising with loads corresponding to 20–40% of an individual’s maximum strength level (e.g., 1-RM) will likely maximize muscle growth and strength (Lixandrao et al., 2015; Counts et al., 2016). When loads used are at the bottom end of this recommendation (e.g., ∼20% of 1-RM), a higher pressure (∼80% AOP) may be required necessary to elicit muscle growth (Lixandrao et al., 2015), however, further study is warranted to confirm this.
In conclusion, we suggest that exercise loads between 20 and 40% 1RM be used because this range of loads has consistently produced muscle adaptations when combined with BFR.

Volume
In the BFR-RE literature, a common and frequently used set and repetition scheme exists that involves 75 repetitions across four sets of exercises, with 30 repetitions in the first set and 15 repetitions in each subsequent set (Yasuda et al., 2006, 2010a,b, 2011a,b, 2012; Madarame et al., 2008; Rossow et al., 2012; Ozaki et al., 2013; Loenneke et al., 2016; May et al., 2017). It is also common to complete 3–5 sets to concentric failure during BFR- RE (Takarada et al., 2002; Cook et al., 2007, 2013; Loenneke et al., 2012a; Manini et al., 2012; Nielsen et al., 2012; Ogasawara et al., 2013; Fahs et al., 2015). Furthermore, repetitions to failure may not be needed in practical settings, such as post-surgery rehabilitation of clinical populations. For example, doubling this volume of load lifted does not appear to augment any adaptations (Loenneke et al., 2011b; Martín-Hernández et al., 2013), although the dose-response relationship between volume and adaptation
still needs further clarity. Therefore, it is suggested 75 repetitions, across four sets (30, 15, 15, 15) is sufficient volume to lead to adaptations in most people. Working to failure is another possibility to induce adaptations but may not always be required.


Rest Periods
Inter-set rest periods used during BFR-RE are generally short and typically the restriction is maintained throughout this period. For example, Loenneke et al. (2012d) conducted a meta-analysis that demonstrated strength adaptations with both 30 and 60 s inter-set rest periods. Some acute research has used rest periods as long as 150 s (Loenneke et al., 2010), but this was not found to increase metabolic stress any more than LL-RE, and thus may not provide training benefits. However, rest periods of both 30 s (Yasuda et al., 2010a, 2015b; Loenneke et al., 2011a) and 30–60 s (Madarame et al., 2010; Patterson and Ferguson, 2010, 2011; Yasuda et al., 2015b; Loenneke et al., 2016; Ladlow et al., 2018) are common within the BFR literature, which reflects the recommendations for achieving skeletal muscle hypertrophy (Kraemer and Ratamess, 2004). On occasions it is not always required to maintain pressure during rest periods. For example, Yasuda et al. (2013) demonstrated similar muscle activation with both continuous and intermittent pressure during rest periods, but only when a high cuff pressure was applied. Overall we recommend rest periods should constitute 30–60 s, however, intermittent BFR may reduce swelling/metabolic stress compared with continuous, which could limit the stress for adaptation.


Frequency
Traditionally, it is recommended to perform resistance training 2–4 times per week to stimulate skeletal muscle hypertrophy and strength adaptations (Fleck and Kraemer, 2004; Kraemer and Ratamess, 2004). Increases in muscle hypertrophy and strength have been reported with BFR-RE twice weekly (Takarada et al., 2000b, 2002; Laurentino et al., 2008; Madarame et al., 2008), with a recent review advocating that 2–3 BFR-RE sessions per week with progressive overload is sufficient for enhanced strength and hypertrophy adaptations (Scott et al., 2015). Some BFR research has implemented training twice daily (Abe et al., 2005b; Yasuda et al., 2005, 2010b; Nielsen et al., 2012), which may be used to accelerate recovery.

In conclusion, high frequency approaches (1–2 times per day) may be used for short periods of time (1–3 weeks), however, under periods of normal programming, 2–3 sessions per week are ideal.

Duration of Training Programmes
Regarding duration of BFR-RE programmes, muscle hypertrophy and strength adaptations have been observed in short time frames, such as 1–3 weeks (Abe et al., 2005b,c; Yasuda et al., 2005; Fujita et al., 2008; Nielsen et al., 2012). Most studies have examined muscle hypertrophy and strength adaptations over time frames >3 weeks duration (Burgomaster et al., 2003; Moore et al., 2004; Abe et al., 2006; Iida et al., 2011; Nielsen et al., 2012; Yasuda et

 

Adapted from

Blood Flow Restriction Exercise Position Stand: Considerations of Methodology, Application,
and Safety
Stephen D. Patterson1*, Luke Hughes1, Stuart Warmington2, Jamie Burr3, Brendan R. Scott4, Johnny Owens5, Takashi Abe6, Jakob L. Nielsen7, Cleiton Augusto Libardi8, Gilberto Laurentino9, Gabriel Rodrigues Neto10, Christopher Brandner11, Juan Martin-Hernandez12 and Jeremy Loenneke6

 

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