What is the central question of this study? This study sought to determine whether prior upper limb aerobic training can attenuate the vascular dysfunction resulting from negative alteration of blood flow patterns. What is the main finding and its importance? We demonstrated that the microvasculature of young men with prior upper limb aerobic training (rowing) was equally susceptible to negatively altered blood flow patterns when compared with untrained control subjects. This finding reveals that aerobic training does not provide adequate protection against this type of vascular insult, highlighting the importance of reducing known vascular insults regardless of training status.

Vascular function and blood flow responses to upper limb exercise are differentially altered in response to different exercise training modalities. Rowing is a unique exercise modality that incorporates the upper limbs and can significantly augment upper limb endurance, strength, and power capacity. PURPOSE:This study sought to determine whether vascular function and blood flow regulation during handgrip exercise are altered in row-trained males. METHODS:Nine young row-trained males (ROW, 20 ± 1 yr; V˙O2peak = 51 ± 2 mL·kg·min) and 14 recreationally active male controls (C: 22 ± 1 yr; V˙O2peak = 37 ± 2 mL·kg·min) were recruited for this study. Subjects performed multiple bouts of progressive rhythmic handgrip exercise. Brachial artery (BA) diameter, blood flow, shear rate, and mean arterial pressure were measured at rest and during the last minute of each exercise workload. RESULTS:Resting values for BA diameter, blood flow, shear rate, and mean arterial pressure were not different between groups. During handgrip exercise, the ROW group reported significantly lower BA blood flow (ROW vs C: 4 kg [146 ± 21 vs 243 ± 13 mL·min], 8 kg [248 ± 29 vs 375 ± 17 mL·min], 12 kg [352 ± 43 vs 490 ± 22 mL·min]) across all workloads when compared with controls. The examination of BA dilation, when controlled for the shear rate stimulus and evaluated across all workloads, was revealed to be significantly greater in ROW group versus controls. CONCLUSION:This study revealed that vascular function and blood flow regulation were significantly different in row-trained males when compared with untrained controls evidenced by greater shear-induced BA dilation and lower arm blood flow during progressive handgrip exercise.

PURPOSE: This study sought to examine the role of oxidative stress in sitting-induced vascular dysfunction across genders. METHODS: On two separate occasions, ten males (25±5 yrs) and eleven females (23±3 yrs) had leg vascular function assessed using passive leg movement (PLM) technique before and after 1.5 hours of sitting. Superficial femoral artery (SFA) blood flow and shear rate patterns, heart rate, mean arterial pressure (MAP), and calf circumference (CC) were measured throughout sitting. One gram of vitamin C (VC) or placebo (PL) was consumed 1.5 hours prior to each sitting trial. RESULTS: All subjects (n=21), regardless of condition (PL or VC), reported significantly decreased SFA blood flow (-28.6±41.8 ml/min; p<0.01) and shear rate (−11.3±15.5 s−1; p<0.01) as well as a significant increase in MAP (3.6±5.1 mmHg; p<0.01) and CC (1.2±0.3 cm; p<0.01) after 1.5 hours of sitting. In the PL trial, a significant decline in leg vascular function, evaluated as ΔPLMPEAK, was evident in males, but not females [(-210±51 Δml/min) v. (-43±46 Δml/min); p=0.02] after 1.5 hours of sitting. In the VC trial, both groups revealed no significant declines in ΔPLMPEAK [(-17±51 Δml/min) v. (-81±46 Δml/min); p=0.33]. CONCLUSION: This study revealed that females, but not males, display a resistance to sitting-induced lower limb vascular dysfunction. The vascular dysfunction was significantly attenuated with antioxidant supplementation in males, but not females, which implies a greater inherent antioxidant defense and vascular protection in the lower limb vasculature of females.

Prolonged sitting has been reported to have deleterious effects on lower limb vascular function. High amounts of aerobic fitness are associated with positive vascular adaptations that could potentially provide a protective effect on this sitting-induced vascular insult. PURPOSE: This study examined the effect of aerobic capacity on vascular function after a bout of prolonged sitting. METHODS: Ten young (25 ±3 yrs) aerobically trained subjects (VO2max: 52 ±7 ml/kg –1min –1) and ten young (23 ±2 yrs) sedentary (VO2max: 38 ±5ml/kg –1min –1) subjects matched for age and gender were recruited for the study. During the prolonged sitting session, vascular function, via passive leg movement (PLM), was measured at baseline, 1.5 hours and 3 hours with Doppler ultrasonography. RESULTS: Vascular function data obtained prior to sitting revealed no significant difference between the high (HAC) and low (LAC) aerobic capacity groups. Independent of group, vascular function was significantly reduced after 1.5 and 3 hours of prolonged sitting, determined by Δ Peak LBF and LBF AUC. Interestingly, no significant between–group differences were revealed in Δ Peak LBF or LBF AUC at 1.5 hours [Δ Peak LBF (LAC: –370 ±317 ml[BULLET OPERATOR]min-1; HAC: –167 ±258 ml[BULLET OPERATOR]min –1; p>0.05), LBF AUC (LAC: -149 ±201 ml[BULLET OPERATOR]min –1; HAC: –94.7 ±90 ml[BULLET OPERATOR]min –1; p>0.05), or at 3 hours [Δ Peak LBF (LAC: –373 ±268 ml[BULLET OPERATOR]min –1; HAC: -243 ±299 ml[BULLET OPERATOR]min –1; p>0.05), LBF AUC (LAC: –119 ±202 ml[BULLET OPERATOR]min –1; HAC: -91 ±132 ml[BULLET OPERATOR]min –1); p>0.05]. CONCLUSION: This study found that aerobic capacity did not mitigate the vascular dysfunction resulting from prolonged sitting.

This study examined if the degree of aerobic training protects against the lower limb vascular dysfunction associated with a prolonged sitting bout. Ten young, aerobically trained (AT) and 10 young, untrained (UT) individuals completed a prolonged (3 h) sitting bout. Leg vascular function was measured prior to and at 1.5 and 3 h into the prolonged sitting bout using the passive leg movement (PLM) technique. PLM-induced hyperemia was significantly reduced from baseline at 1.5 and 3 h into the prolonged sitting bout in both groups when evaluated as peak change in leg blood flow from baseline (Δ LBF) (UT: 956 ± 140, 586 ± 80, and 599 ± 96 mL·min-1 at baseline, 1.5 h, and 3 h, respectively; AT: 955 ± 183, 789 ± 193, and 712 ± 131 mL·min-1 at baseline, 1.5 h, and 3 h, respectively) and LBF area under the curve (UT: 283 ± 73, 134 ± 31, and 164 ± 42 mL·min-1 at baseline, 1.5 h, and 3 h, respectively; AT: 336 ± 86, 242 ± 86, and 245 ± 73 mL·min-1 at baseline, 1.5 h, and 3 h, respectively), but no significant differences between groups were revealed. No significant correlations were observed when examining the relationship between maximal oxygen uptake (relative and absolute) and reductions in leg vascular function at 1.5 and 3 h into the prolonged sitting bout. This study revealed that aerobic training did not provide a protective effect against prolonged sitting-induced lower limb vascular dysfunction and further highlights the importance of reducing excessive sitting in all populations.

PURPOSE: This study sought to examine the impact of upper arm aerobic training on peripheral hemodynamics during exercise. METHODS: Seven young male trained rowers (20±1 yrs) and seven male recreationally active controls (24±1 yrs) with no history of upper limb aerobic training were recruited for this study. Subjects performed three minute bouts of progressive rhythmic handgrip exercise (4, 8, and 12 kg). Brachial artery diameter and velocity (Doppler ultrasound), heart rate (ECG), and blood pressure (Tango M2) were continuously measured at rest and during each workload. RESULTS: Resting values for brachial artery diameter, blood flow, mean arterial pressure, and heart rate were not different between rowers and controls (p>0.05). During exercise, the rowers reported significantly reduced brachial artery blood flow [4 kg (146 vs 243 ml/ min); 8 kg (249 vs 417 ml/min); 12 kg (356 v 536 ml/min) p<0.05] and shear rate [4 kg (289 v 470 s-1); 8 kg (439 v 720 s-1); 12 kg (478 v 797 s-1) p<0.05] across all workloads when compared to controls. Brachial artery dilation, when normalized for shear rate, was significantly greater in rowers than controls during 8 and 12 kg workloads (p<0.05). Exercising heart rate and mean arterial pressure were not different between groups (p>0.05). CONCLUSIONS: The results from this study revealed rowers have improved vasoreactivity to a given shear rate stimulus when compared to untrained controls. These findings suggest that upper limb aerobic training results in improved efficiency of blood flow regulation during exercise.