Leg Blood Flow Following Acute Exercise In Adults With A History Of COVID-19

Individuals with a history of COVID-19 have vascular dysfunction that has been implicated in reduced exercise capacity. In response to small muscle mass handgrip exercise, individuals with a history of COVID-19 have a blunted vasodilatory and hyperemic response. Whether this vascular dysfunction in response to exercise is systemic in nature is unknown. The blood flow response to exercise is heterogenous across limbs and exercise modalities. PURPOSE: To determine whether the leg blood flow response to acute large muscle mass leg (cycling) exercise is lower in adults with versus without a history of COVID-19. METHODS: Twenty adults with a past diagnosis of COVID-19 (mean age = 22 ± 4 years, BMI = 25 ± 3 kg/m2, n = 14 women) and 15 controls without a COVID-19 history (mean age 24 ± 6 years, BMI = 25 ± 4 kg/m2, n = 9 women) completed 30-minutes of moderate intensity cycling exercise (65-75% of age-predicted maximal heart rate). Mean arterial pressure (MAP) was measured using a brachial oscillometric cuff before, 5-min, and 30-min after exercise. Superficial femoral artery (SFA) diameter and blood velocity were acquired with Doppler-ultrasound at the same time points and used to derive SFA blood flow conductance. SFA pulsatility index (PI) was additionally calculated using peak systolic (Vs), diastolic (Vd), and mean velocities (MnV) as PI = (Vs - Vd)/MnV. Data were analyzed using a 2-group x 3-time point analysis of variance with repeated measures. RESULTS: Quantitative experimental data are presented in the Table. No group effects or group-by-time interactions were detected for any of the outcome variables (p > 0.05 for all). Time effects were noted for all outcome variables (p < 0.001 for all). Both groups experienced similar increases in diameter and conductance concomitant with reductions in PI at 5-min post followed by recovery toward resting values at 30-min post. CONCLUSIONS: COVID-19 may not affect the lower limb blood flow response to dynamic cycling exercise. - SFA blood flow response to acute exercise. *Significantly different from Pre (p < 0.05). SFA Variable Group Pre 5-min Post 30-min Post P-value for Interaction (Effect Size) Diameter, mm CONTROL 5.02 ± 0.79 5.38 ± 0.72* 5.04 ± 0.85 0.55 (0.04) COVID-19 4.74 ± 0.73 5.02 ± 0.63* 4.83 ± 0.78 Conductance, ml/min/mmHg CONTROL 1.66 ± 0.74 2.80 ± 0.98* 1.90 ± 1.30 0.74 (0.02) COVID-19 1.54 ± 0.74 2.60 ± 1.16* 1.93 ± 1.11 Pulsatility Index, aU CONTROL 8.65 ± 5.14 5.41 ± 2.25* 7.77 ± 3.05 0.73 (0.02) COVID-19 9.36 ± 7.64 5.27 ± 2.30* 7.29 ± 3.70