This week for our sports science journal club Chris Brander looked at the paper below, which examined the effects of walking with blood flow restriction (BFR) on cardiovascular endurance in elite athletes.
Park S, Kim JK, Choi HM, Kim HG, Beekley MD, Nho H. Increase in maximal oxygen uptake following 2-week walk training with blood flow occlusion in athletes. European journal of applied physiology. 2010;109(4):591-600.
What was the aim of the paper?
Blood flow restriction (BFR) is a pretty novel exercise technique that is typically used in combination with strength exercise with light loads (20-30% of your predetermined 1 rep max). The benefit to applying a cuff or tourniquet around the limbs and reducing blood flow is an increase in muscle mass and strength similar to lifting much heavier loads (≥ 70% 1 rep max). This has huge implications for healthy populations including athletes, but also for populations that have limited strength capacities due to old age, musculoskeletal injuries, or muscle wasting due to inactivity or disease.
Alternatively, the use of BFR during aerobic modes of exercise such as walking and cycling has also been shown to be beneficial in improving gains in muscle strength and mass in both trained and untrained populations. While the research is not clear, the use of walk exercise with BFR may improve aspects of cardiovascular fitness; such as the maximal rate of oxygen consumption (VO2max), resting heart rate and resting blood pressure. So, the aim of this paper was to assess changes in cardiovascular fitness following a short duration training program in an athletic population.
What did the study involve?
Fourteen college male basketball players were recruited for the study and randomized into 2 training groups; walk training with BFR or walk training without BFR. The walk training consisted of 2 training sessions per day (morning and afternoon), 6 days per week, for 2 weeks (24 training sessions in total). Each training session involved walking for 5 sets of 3-minute bouts, interspersed with a 1-minute recovery period, at approximately 40% of their pre-determined VO2max.
For the BFR group a cuff was placed around the upper most portion of each leg and inflated to a pressure of 160-220 mmHg prior to each training session. The cuff remained inflated for the entire exercise bout including rest periods (22 minutes) and was immediately released at the end of the 5th set.
What were the main results?
The researchers found that following training, walking with BFR improved both VO2max (48.9 to 54.5 ml.kg.min – 11.6%) and VEmax (10.6%), whereas there was no change following walk training without BFR. Interestingly, unlike previous research, this study did not find any changes in either groups in lower body power (determined by a 30 second maximal Wingate sprint on a cycle ergometer), and no change in isokinetic knee extension strength.
What can we take from it?
This was the first study to show that a short period of low-intensity aerobic exercise with BFR improves cardiovascular endurance in elite athletes. What is really interesting about this study is that the improvement shown in VO2max was similar to other studies in athletes following high intensity exercise (i.e. 60-70% VO2max) over similar training periods.
From a coaching and practical point of view, research into the area of BFR is consistently demonstrating that we don’t have to train at high intensities or with heavy loads to induce changes in aerobic capacity and build muscle strength and mass. This doesn’t mean you should stop lifting those heavy weights or completing HIIT sessions, but perhaps provides an alternative stimulus to keep on improving once you reach a performance plateau or could be used as an in-season training modality to reduce the stress placed on you or your athletes’ body.
This study was well written and provided some nice images of the BFR walking if you are interested in how to set it up, as well as the important results in easy to read graphs and tables. One limitation of the study was that there was no reporting of any additional training (skills training, weights etc) that may have been completed during the study. This may have had a huge impact on the results if the athletes were completing any additional exercise. It also would have been a better study design if they directly compared the change in VO2max with a group that completed a similar volume of high intensity aerobic exercise.