Age and VO2max
(1) Does VO2max change as one gets older? In a non-training male individual, the VO2max will increase markedly at puberty (to 20-25 nmol/L) due to the effects of testosterone on lean body mass and increased haematocrit. Males undergo a steady decline in serum testosterone from the age of about 25 onwards. Just as with serum testosterone and lean body mass, the active individual will still have a steady decline in VO2max; however the rate of decrease will be lessened. At 85 years old the serum testosterone is likely to be less than 15 nmol/L. There are similar declines in growth hormone, IGF-1 and DHEA.
So with no training, the physiological and psychological effects of variable serum testosterone will exert a significant effect on VO2max. Emotional maturity and mental discipline will also affect measurable VO2max. It will be more difficult to take an 8 year old to volitional failure than a 25 year old. The average VO2max of a 20-24 year old male is around 39 mls/min/kg. This drops to around 23 in the average 60-65 year old male. The drop from (age) 20?s to 60?s in males and females is the same at about 20 mls/min/kg. This is in the average, fairly sedentary male. It will be higher to begin with in the aerobic training male, and the drop with age will be less in the life-long aerobic exerciser.
If you have an male individual who is engaged in regular aerobic training, this will induce adaptive changes specific to aerobic performance, such as increased capillary density, increased cardiac stroke volume, increased mitochondrial density, increased aerobic enzyme activity, lactate buffering capacity, and alterations in muscle phenotype. Three types of muscle fibre are generally described in training articles. In reality there are many more subtle sub-types and the number is increasing. Fast (white/glycolytic), slow (red/aerobic), and a transitional type are adequate to describe training adaptation. The transitional type will begin to behave more like the slow / aerobic type with focused aerobic training. All of these adaptations will increase VO2max and aerobic performance, independent of testosterone. This may take 5-10 years, and this is reflected in the average age of peak performance in endurance events. Taylor Phinney will get faster?terrifying.
(2) Metabolism / buffering of lactate /lactic acid with age ? Not sure if there are age related changes in buffering independent of other variables such as enzyme concentration, muscle fibre type, training status etc. Lactate dehydrogenase activity which is crucial to lactate metabolism responds well to aerobic training in the elderly, so it is likely that the majority of decline in lactate tolerance is due to detraining.
(3) Constant training and jump in watts/kg at puberty ? Yes, this should happen via the mechanism described above in (1).
All of the above is complicated by maturity, school commitments, working etc. Ethics committees would frown on removing kids from elementary / primary school to subject them to an intense training regime for the next 20 years, however, the results would be very interesting.