Objective : To investigate vascular adaptations to eight weeks of resistance exercise, with and without different pressures of blood flow restriction (BFR), in the upper and lower body. Approach : Forty individuals (men = 20, women = 20) completed eight weeks of resistance exercise at very low loads (15% of one-repetition maximum (1RM)), with two levels of BFR (40% arterial occlusion pressure (AOP), 80% AOP), without BFR, and 70% of 1RM. Vascular conductance and venous compliance were measured via plethysmography before and following training in the forearms and in the calves. Main results : Values reported as means (95% confidence intervals). Pre to post changes in vascular conductance occurred only in the high-pressure conditions (upper body: +8.29 (3.01–13.57) ml · mmHg ⁻¹ ; lower body: +7.86 (3.37–12.35) ml · mmHg ⁻¹ ) and high-load conditions (upper body: +8.60 (3.45–13.74) ml · mmHg ⁻¹ ); lower body: +7.20 (2.71–11.69) ml · mmHg ⁻¹ ) only. In the upper body, the change was significantly greater in the high-pressure and high-load conditions compared to the change observed in the low-pressure condition (−0.41 (−5.56, 4.73) ml · mmHg ⁻¹ ). These changes were not greater than the change observed in the low-load condition without pressure (+1.81 (−3.47, 7.09) ml · mmHg ⁻¹ ). In the lower body, the change in the high-pressure and high-load conditions were significantly greater than the changes observed with low-load training with (−0.86 (−5.60, 3.87) ml · mmHg ⁻¹ ) and without (−1.22 (−5.71, 3.27) ml · mmHg ⁻¹ ) a low pressure. Venous compliance increased in all groups in the upper body (+0.003 (.000 08, 0.006) ml · 100 ml ⁻¹ · mmHg ⁻¹ ) only, with no changes in the lower body. Significance : High-pressure BFR causes adaptations in vascular function following eight weeks of training at mechanical loads not typically associated with such adaptations.

The purpose was to examine changes in the perceptual responses to lifting a very low load (15% one repetition maximum (1RM)) with and without (15/0) different pressures [40% (15/40) and 80% (15/80) arterial occlusion pressure] and compare that to traditional high load (70/0) resistance exercise. Ratings of perceived exertion (RPE) and discomfort were measured following each set of exercise. In addition, resting arterial occlusion pressure was measured prior to exercise. Assessments were made in training sessions 1, 9, and 16 for the upper and lower body. Data are presented as means and 95% CI. There were changes in RPE in the upper body with condition 15/40 [−2.1 (−3.4, −0.850)] and 15/80 [−2.4 (−3.6, −1.1)] decreasing by the end of training. In the lower body, RPE decreased in condition 15/40 [−1.4 (−2.3, −0.431)] by the end of the training study. There was a main effect of time in the upper body with all conditions decreasing discomfort. In the lower body, all conditions decreased except for 15/80. For arterial occlusion pressure, there were differences across time in the 15/40 condition and the 15/80 condition in the upper body. Repeated exposure to blood flow restriction may dampen the perceptual responses over time.

Low‐load exercise performed to or near task failure appears to result in similar skeletal muscle adaptations as low‐load exercise with the addition of blood flow restriction (BFR). However, there may be a point where the training load becomes too low to stimulate an anabolic response without BFR. This study examined skeletal muscle adaptions to very low‐load resistance exercise with and without BFR. Changes in muscle thickness (MTH), strength, and endurance were examined following 8‐weeks of training with a traditional high‐load [70% 1RM,(7000)], low‐load [15% 1RM,(1500)], low‐load with moderate BFR [15%1RM + 40%BFR(1540)], or low‐load with greater BFR [15% 1RM + 80%BFR(1580)]. 1RM strength changes were greater in the 7000 condition [2.09 (95% CI = 1.35–2.83) kg] compared to all low‐load conditions. For isometric and isokinetic strength, there were no changes. For endurance, there was a main effect for time [mean pre to post change = 7.9 (4.3–11.6) repetitions]. At the 50% site, the mean change in MTH in the 7000 condition [0.16 (0.10–0.22) cm] was greater than all low‐load conditions. For the 60% site, the mean change in MTH [0.15 (0.08–0.22)] was greater than all low‐load conditions. For the 70% site there was a main effect for time [mean pre to post change = 0.09 (0.05–0.14 cm]. All groups increased muscle size; however, this response was less in all very low training conditions compared to high‐load training. 1RM strength increased in the 7000 condition only, with no other changes in strength observed.

Maximal strength testing is often performed to assess the efficacy of training programs or as a way to prescribe exercise load. Generally, it is believed that high load exercise is superior to low load exercise at increasing absolute strength, however this is not always the case (i.e. strength increases similarly between groups). We hypothesized that some of the discrepancy in the literature may be related to performing the strength test itself. To investigate this further we reviewed the literature looking for studies comparing high load and low load exercise. The included studies were separated into ‘no extra practice’ and ‘practice’. No extra practice means the strength test was only performed at pre and post whereas practice refers to additional strength tests performed throughout the training intervention. Our results indicated that the differences between high load and low load exercise can be reduced when the group training with a low load is allowed additional exposure to the maximal strength test. This suggests that repeated exposure to strength tests may augment low load training adaptations and influence the outcomes. We discuss potential moderators of this relationship (e.g. how low is the low load, complexity of the skill) and offer considerations for future research. Based on this it would be recommended that when investigating the effects of low load training strength tests should be limited to pre and post intervention or if a control group is utilized then the control group should receive the same number of exposures to the strength test.