Influence of Absolute Force on Augmented Exercise Blood Pressure During Isometric Hand-gripping with Female Aging

PURPOSE: Post-menopausal females exhibit the highest exercising blood pressure (BP) of any age and sex group. Such responses are associated with elevated risk for adverse cardiovascular events. Recent work indicates that absolute handgrip (HG) force influences exercise BP responses. However, the role of absolute handgrip (HG) force on BP responses in female aging has yet to be addressed. Therefore, we sought to determine whether there would be differential relations between absolute HG load and BP in younger and older female participants. METHODS: We analyzed data from older (OF; n = 9; age: 66 ± 6 years, body mass index (BMI): 23 ± 3 kg/m2) and younger (YF; n = 14; age: 24 ± 5 years, BMI: 22 ± 3 kg/m2) females. We measured beat-to-beat BP (photoplethysmography; Finometer) while participants lay supine. Participants performed isometric HG exercise at 30% of their maximal voluntary contraction for two minutes. We employed a mixed-effects model to assess the effects of HG and age on systolic (SBP) and diastolic (DBP) BP. We also used linear regression to evaluate the impact of age and absolute HG loads on BP responses. RESULTS: Across baseline and minute 2 of HG exercise we found a significant effect of age on BP (SBP p < 0.001, DBP p = 0.048). OF had higher SBP at baseline (OF: 146 ± 22 vs. YF: 107 ± 7, p < 0.001) and during minute two of HG exercise (OF: 168 ± 32 vs. YF: 125 ± 9 p < 0.001) compared with YF. OF had an exaggerated ΔSBP during HG exercise (OF: Δ27 ± 12 vs. YF: Δ18 ± 7 mmHg, p = 0.026), but there was no age difference for exercising ΔDBP (p = 0.885). HG load was not related to BP responses in OF (R2 = 0.28, p = 0.1746) or YF (R2 = 0.05, p = 0.4372) and there was no between group difference in the relation between HG load and BP responses (p = 0.1615). CONCLUSIONS: In line with previous findings, we found that older females had augmented BP during HG exercise. However, BP responses were not related to HG load in either age group of female participants. Future investigations are needed to elucidate the relations between absolute load and BP responses among females across the life span.