Aging increases metabolic capacity and reduces work efficiency during handgrip exercise in males

Area of Science:

• Exercise Physiology
• Aging Research
• Vascular Function

Background:

• Maximal oxygen uptake and exercise performance typically decrease with age.
• Previous studies suggest preserved vascular function and blood flow regulation during arm exercise in older adults.
• The impact of aging on peripheral metabolic capacity and oxygen uptake per work unit (V̇o₂/W) in the arms remains unclear.

Purpose of the Study:

• To investigate the effects of aging on metabolic and vascular responses during dynamic handgrip exercise in males.
• To compare peripheral metabolic capacity and V̇o₂/W ratio between young and old males during arm exercise.

Main Methods:

• Measured metabolic and vascular responses during 6-minute handgrip exercise at 40% and 80% of maximal work rate (WR_max).
• Studied 11 young (26±2 yr) and 12 old (80±6 yr) males.
• Utilized Doppler-ultrasound and blood sampling from a deep forearm vein.

Main Results:

• Older males exhibited higher V̇o₂, blood flow, and oxygen supply at both exercise intensities compared to young males.
• Older males had a lower arteriovenous oxygen difference at 80% WR_max and a higher oxygen excess.
• Young males showed intensity-induced arterial dilation, while older males had a higher mean arterial pressure at 80% WR_max; V̇o₂/W was reduced in older males.

Conclusions:

• Older males demonstrate increased forearm metabolic capacity during handgrip exercise, mediated by enhanced forearm blood flow.
• Despite a higher V̇o₂/W ratio, older adults can achieve similar maximal work rates in arm exercise as younger individuals.
• Preserved arm exercise capacity in aging may be attributed to available cardiac output reserve, compensating for reduced work efficiency.