With age, we tend to see an increase in "fatigability" while the capacity for mitochondrial energy production decreases. Logically, this correlation makes sense; diminished mitochondrial function may contribute to higher levels of fatigability the older we get.
To confirm whether this is truly due to mitochondrial function (or dysfunction as we age), researchers investigated the relationship between fatigability and skeletal muscle mitochondrial
function in 30 participants with an average age of 78.5 years. Fatigability was defined using
rating of perceived exertion after a 5-minute
treadmill walk at 0.72 m/s. Phosphocreatine recovery in the quadriceps
was measured using magnetic resonance spectroscopy and
images of the quadriceps were captured to calculate quadriceps volume.
ATPmax (amount of ATP--the energy currency in cells--replenished per second) and oxidative capacity (the capacity to product energy via aerobic respiration in the mitochondria) of the quadriceps
(ATPmax·Quadriceps volume) were calculated. Peak aerobic capacity (VO2peak) was measured using a modified Balke protocol.
ATPmax·Quadriceps volume was associated with VO2peak and was lower in those with high a rating of
perceived exertion (≥10) versus low rating of perceived exertion (≤9). Participants with high fatigability required a
significantly higher proportion of VO2peak to walk at 0.72
m/s compared with those with low fatigability. After adjustment for age and sex, higher ATPmax was
associated with lower odds of having high fatigability.
In plain language, lower capacity for energy production by the mitochondria in the quadriceps (perhaps by contributing to lower VO2peak) is associated with higher fatigability in older adults.
These results would mean nutrients that support mitochondrial health (CoQ10/ubiquinol, magnesium, L-carnitine, PQQ, etc.) are likely of significant benefit to active seniors.
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Source: Skeletal Muscle Mitochondrial Function and Fatigability in Older Adults