Front Load Carriage Has Sex-Specific and Perhaps Occupational Risk Implications for Cardiovascular Health

Background: Load carriage is an essential part of the occupational work of many jobs, yet there is little research on the hemodynamic responses to load carriage. It is known that front load carriage elicits larger increases in arterial stiffness than load carried on the side of the body. However, the hemodynamic forward and reflected pulse wave responses to load carriage are unknown and could relate to cardiac risk. Methods: We compared responses to 30 s front load carriage between 45 females and 23 males, with pre- and post-carry hemodynamics assessed using pulse wave analysis. Results: We found increases (p < 0.001) in arterial stiffness (24.8% females; 32.4% males), forward pulse wave (5.8 mmHg females; 5.7 mmHg males), and reflected pulse wave (6.8 mmHg females; 9.9 mmHg males). Pre- and post-carriage forward and reflected pulse waves were lower in females (p < 0.05). Compared to males, females overall had more relationships between the change in vascular measurements and other variables. We found an inverse relationship between changes in myocardial supply–demand (SEVR) and changes in forward pulse wave in females (r = −0.37, p < 0.001) but not males. Also, a direct relationship between changes in SEVR and changes in aortic DBP (r = 0.30, p = 0.04) and changes in resting DBP (r = 0.35, p = 0.02) existed in females. Conclusions: The data suggest that sex-related differences in hemodynamic responses exist. Females may experience a larger drop in estimated myocardial supply–demand balance accompanied by lower diastolic filling. Employers should be aware of these inherent cardiac risks with load carriage in their female employees.