Maturity and Physiological questions...

[TRDean]

I was hoping to get some answers to some sports physiology questions here. I am interested in the development of young athletes. Specifically as they progress through puberty. First, does the VO2 max change as one gets older? How about the body's ability to metabolize lactic acid? Do these things change as a person goes through puberty, regardless of whether they are training or not? Lastly, as a person goes through development you would expect to see an increase in power output if training stays constant simply because the muscles are growing correct? But could you notice a substantial jump in watts/kg simply by entering puberty? Thanks for all the help!!

Tim

 

[therealdjamolidineabdoujaparov]

age and physiology changes

Hi,
These are fantastic questions and I would not do justice to them to post a short answer. I imagine you realise that for several reasons these are complex issues. I am a little busy this week, however, I will give what I can contribute to your questions later in the week.

 

[Charles Howe]

I am interested in the development of young athletes. Specifically as they progress through puberty. First, does the VO2 max change as one gets older?

Genetically, (i.e., irrespective of training), I will hazard a guess that it reaches a peak around age 20.

How about the body's ability to metabolize lactic acid?

Dunno, but I believe Lydiard was correct to empahsize aerobic development in young athletes.

Lastly, as a person goes through development you would expect to see an increase in power output if training stays constant simply because the muscles are growing correct?

Yes, but not so much b/c the muscles are growing, but becoming more developed (i.e., vascularized, particularly at the cappilary level, and generating more mitochondria).

But could you notice a substantial jump in watts/kg simply by entering puberty?

Seems logical.

 

[therealdjamolidineabdoujaparov]

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.

 

[TRDean]

Thanks very much for the information. You have explained things that I thought were probably true...but in great detail...it is much appreciated.

I had always hypothesized that if a young person (male or female) were to begin some activity at a prepubescent age then their bodies would compensate to a great extent as the child moved through their development years. It seems this is probably the case.

Once again thanks for the time in answering my question.

Tim