Acute muscle swelling is a purported mechanism for muscle hypertrophy following blood flow restriction (BFR) training. Currently there are numerous cuff widths used within the lower body BFR literature. However, studies suggest that growth may be attenuated with a wider cuff. Whether this is related to a differential acute swelling response has not been previously shown. PURPOSE: To examine the acute changes in muscle swelling following low load BFR exercise in the lower body, in response to different cuff widths inflated to the same relative pressure. METHODS: Ninety-six (43 men, 53 women) participants completed two conditions (one each leg). Participants completed four sets of unilateral knee extension exercise to failure using 30% of their one repetition maximum (1RM) with BFR applied with either a narrow (5 cm) or a wide (12 cm) cuff inflated to 40% of their arterial occlusion pressure. Muscle thickness and echo intensity were measured at two sites (proximal and distal) before and after each exercise bout as surrogate markers of swelling. A repeated measures analysis with a between subject factor of sex was used to assess changes. Bayes Factors (BF₁₀) were used to quantify evidence. RESULTS: The difference in acute changes in muscle thickness (BF₁₀: 0.43) and echo intensity (BF₁₀: 0.87) between cuff widths was not different between the proximal (i.e. wide cuff covered this site) and distal (no cuff was over this site) location. Further, changes in muscle thickness at the proximal [5cm: 0.58 cm vs. 12 cm: 0.57 cm; median difference (95% credible interval) of 0.009 (-0.04, 0.06) cm] and distal [5 cm: 0.63 cm vs. 12 cm: 0.63 cm; median difference (95% credible interval) of 0.00002 (-0.03, 0.04) cm] site did not differ based on cuff width or sex (Men: 0.58 cm vs. Women: 0.57 cm and Men: 0.64 cm vs. Women: 0.63 cm for proximal and distal sites, respectively). Echo intensity appeared to decrease at the proximal and distal sites with no differences between cuff widths. However, there was some evidence that this change at the distal site may be different between sexes [BF₁₀: 49.8; Men: -1.9 vs. Women: -4.2 AU). CONCLUSIONS: Acute muscle swelling occurs in men and women, even when using a wider cuff. Thus, if there is to be attenuation in growth with a wider cuff, it is unlikely to be due to differences in acute swelling.