Acute Muscular Responses to Practical Low-Load Blood Flow Restriction Exercise Versus Traditional Low-Load Blood Flow Restriction and High-/Low-Load Exercise.
CONTEXT
Blood flow restriction (BFR) increases muscle size and strength when combined with low loads, but various methods are used to produce this stimulus. It is unclear how using elastic knee wraps can impact acute muscular responses compared with using nylon cuffs, where the pressure can be standardized.


OBJECTIVE
Investigate how elastic knee wraps compare with nylon cuffs and high-load (HL)/low-load (LL) resistance exercise.


DESIGN
A randomized cross-over experimental design using 6 conditions combined with unilateral knee extension.


SETTING
Human Performance Laboratory.


PARTICIPANTS
A total of 9 healthy participants (males = 7 and females = 2) and had an average age of 22 (4) years.


INTERVENTION
LL (30% of 1-repetition maximum [1-RM]), HL (70% 1-RM), BFR at 40% of arterial occlusion pressure (BFR-LOW), BFR at 80% of arterial occlusion pressure (BFR-HIGH), elastic knee wraps stretched by 2 in (PRACTICAL-LOW), and elastic knee wraps stretched to a new length equivalent to 85% of thigh circumference (PRACTICAL-HIGH). BFR and practical conditions used 30% 1-RM.


MAIN OUTCOME MEASURES
Muscle thickness, maximum voluntary isometric contraction, and electromyography amplitude. Bayesian statistics evaluated differences in changes between conditions using the Bayes factor (BF10), and median and 95% credible intervals were reported from the posterior distribution.


RESULTS
Total repetitions completed were greater for BFR-LOW versus PRACTICAL-HIGH (BF10 = 3.2, 48.6 vs 44 repetitions) and greater for PRACTICAL-LOW versus BFR-HIGH (BF10 = 717, 51.8 vs 36.3 repetitions). Greater decreases in changes in maximum voluntary isometric contraction were found in PRACTICAL-HIGH versus HL (BF10 = 1035, ∼103 N) and LL (BF10 = 45, ∼66 N). No differences in changes in muscle thickness were found between LL versus PRACTICAL-LOW/PRACTICAL-HIGH conditions (BF10 = 0.32). Greater changes in electromyography amplitude were also found for BFR-LOW versus PRACTICAL-HIGH condition (BF10 = 6.13, ∼12%), but no differences were noted between the other BFR conditions.


CONCLUSIONS
Overall, elastic knee wraps produce a more fatiguing stimulus than LL or HL conditions and might be used as an alternative to pneumatic cuffs that are traditionally used for BFR exercise.
['Thiebaud|Robert S|RS|', 'Abe|Takashi|T|', 'Loenneke|Jeremy P|JP|', 'Garcia|Tyler|T|', 'Shirazi|Yohan|Y|', 'McArthur|Ross|R|']
D000328:Adult D018592:Cross-Over Studies D004576:Electromyography D005260:Female D006801:Humans D008297:Male D053580:Muscle Strength D052097:Quadriceps Muscle D012039:Regional Blood Flow D055070:Resistance Training D014111:Tourniquets D055815:Young Adult
elastic knee wraps muscle thickness vascular occlusion