Blood flow–restricted walking does not result in an accumulation of metabolites

Abstract

The American College of Sports Medicine recommends lifting a weight of at least 70% of one's concentric one repetition maximum to achieve muscular hypertrophy as it is believed that anything below this intensity does not produce significant muscle growth. Recent studies have found muscle hypertrophy to occur with low-intensity 'aerobic-like' exercise with the application of blood flow restriction (BFR) to the limbs. Previous research with low load resistance training has shown that elastic knee wraps provide a practical means to induce elevations in whole blood lactate (WBL), which has been hypothesized to result in many of the adaptations observed with this type of exercise. However, this has yet to be investigated with low-intensity walking. Thus, the purpose of this paper was to determine the degree to which WBL increases with practical BFR walking. Exercise consisted of five 2-min bouts of walking at 75 m per min on a motor-driven treadmill with a 1-min rest period following each exercise bout. Participants completed the walking with (BFR) and without [control (CON)] restriction to the upper thigh in a randomized order. Practical BFR with elastic knee wraps did statistically increase WBL compared with CON; however, this was not considered a real change because the minimal difference between conditions was not exceeded. In conclusion, metabolic stress is not increased following practical BFR walking exercise. This study may provide an explanation for the lower hormone response observed with BFR walking and provide further evidence that mechanisms other than metabolic accumulation exist with BFR.

The acute muscular effects of cycling with and without different degrees of blood flow restriction

“…In contrast, the increase observed with cycling under BFR was small and suggests that lactate accumulation is not occurring to a great degree with this type of exercise. This corroborates previous findings observed following slow walking in combination with BFR (24).…”

“…To illustrate, acute muscle swelling has been observed with slow (56 m/min) and fast BFR walking (87 m/min) without a significant decrease in torque (31), suggesting that muscle fatigue may not be a prominent mechanism with low intensity aerobic exercise. Further, walking at slow speeds does not result in an accumulation of metabolites in the blood (75 m/min) (24), although cycling at 40% of VO2 max does increase lactate levels over baseline values (~2 mmol/L increase) (13), albeit to a lesser extent than that observed with resistance training (26). Therefore, it appears that the predominant mechanism behind the benefits observed with BFR aerobic exercise at low intensities may be the acute increase in muscle cell volume and this increase in cell volume may also be responsible for the increased ERK ½ and p38 phosphorylation and for the decreased phosphorylation of eEF2 observed in young men walking under BFR at 55% VO2 max (32).…”

The Effects of a 7-Week Practical Blood Flow Restriction Program on Well-Trained Collegiate Athletes

“…However, few studies have used elastic knee wraps (17,21,23,24,36), and even fewer have used them outside of a laboratory setting with an athletic population (36). Additional research in this area will provide further insight into the use of practical BFR in those who are already well trained.…”

“…Abe et al (4) observed increased muscular strength and hypertrophy by using BFR in combination with slow treadmill walking. Although Abe did not measure metabolites, Loenneke et al (23) conducted comparable research in which lactate was assessed. Analysis revealed that slow treadmill walking using BFR did not result in metabolite accumulation.…”

Metabolic cost of locomotion during treadmill walking with blood flow restriction

“…The overall characteristics of the training protocol, combining walking and BFR, have been considerably consistent among the existent research examining both chronic (Abe et al ., , ) and acute physiological (Renzi et al ., ; Loenneke et al ., b; Ogawa et al ., ) adaptations in healthy young men. Generally, this protocol has been structured for five bouts of 2–5‐min treadmill walking, at a variable speed between 50 and 87 m min −1 , with a 1‐min rest between each bout.…”