INCREASED CEREBRAL BLOOD VELOCITY DURING ACUTE RESISTANCE EXERCISE IS SIMILAR BETWEEN YOUNG AND OLDER ADULTS
Authors: Lima Natalia S. , Rosenberg Alexander J. , Schroeder Elizabeth C. , Lefferts Wesley K. , Sherman Sara R. , Grigoriadis Georgios , Baynard Tracy 
Published: April 2020

Aging may be accompanied by a reduction in cerebral vascular regulation, especially during increases in blood pressure. Resistance exercise (RE) acutely imposes large increases in blood pressure, but is recommended to combat sarcopenia and promote independent living in older adults. The effects of increased blood pressure during acute RE on cerebral blood velocity in older adults remains unknown.

Purpose

Compare cerebral blood velocity responses during acute RE in young and older adults.

Methods

Twenty‐nine young (25 ± 4 years; 23.9 ± 3.3 kg/m2) and 22 healthy older (60 ± 6 years; 29.6 ± 5.6 kg/m2) adults completed three sets of 10 repetitions of maximal isokinetic concentric/concentric knee extension/flexion contractions. Right middle cerebral artery (MCA) mean blood velocity (mv) was measured at baseline and during exercise using a 2‐MHz transcranial Doppler probe at the temporal window. MCA pulsatility index (PI) was calculated as systolic velocity ‐ diastolic velocity / mv. Beat‐to‐beat systolic, diastolic, and mean blood pressure (SBP, DBP, MAP) were collected at baseline and during the exercise using non‐invasive finger photoplethysmography. Pulse pressure (PP) was calculated as SBP – DBP using a software. Data was averaged over the last 30s of baseline and over a 10s average during the third set of RE. Cerebral vascular conductance (CVC) was calculated as MCA mv/MAP.

Results

MAP increased during RE in both groups, however values were higher and increased more in older compared to young adults (p for interaction <0.05). Older adults had greater overall PP and lower CVC than young adults (see table
, p<0.05). RE increased PP and MCA mv and decreased CVC (p<0.05) in both young and older adults. MCA PI was unaltered during RE in either group (p>0.05).

Conclusion

We observed similar cerebral hemodynamic responses during acute RE in young and older adults, demonstrated by increases in MCA mv, reductions in CVC, and maintained MCA PI. This data suggests that healthy aging may not alter the cerebral blood velocity response to acute increases in blood pressure during RE.

Blood pressure responses and cerebral blood flow velocity of middle cerebral artery at rest and during third set of resistance exercise.

Young

Old

Age

Time

Interaction

Baseline

RE Set 3

Baseline

RE Set 3

MAP (mmHg)

94 ± 7

129 ± 16
§

99 ± 8
*

147 ± 23
*
§

<0.01

<0.01

0.03

PP (mmHg)

50 ± 6

70 ± 12

69 ± 16

96 ± 23

<0.01

<0.01

0.11

MCA mv (cm/s)

61 ± 13

71 ± 22

53 ± 1

65 ± 22

0.08

<0.01

0.73

MCA PI

0.86 ± 0.15

0.81 ± 0.20

0.90 ± 0.20

0.95 ± 0.24

0.65

0.99

0.11

CVC (cm/s/mmHg)

0.65 ± 0.14

0.55 ± 0.17

0.52 ± 0.17

0.45 ± 0.17

<0.01

<0.01

0.63

*Significant differences between age groups, p <0.05;

§Significant differences from baseline, p <0.05.

MAP – mean arterial pressure; PP – pulse pressure; MCA mv – middle cerebral artery mean velocity; MCA PI – middle cerebral artery pulsatility index; CVC – cerebral vascular conductance.