Wednesday, June 2, 2010

VO2 Max: What do we know, and what do we still need to know

VO2 Max: What do we know, and what do we still need to know
By Benjamin D. Levine
Institute For Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, and the University of Texas Southwestern Medical Center at Dallas,TX, USA
From J Physiol 586.1 (2008) pp 25–34
Maximal oxygen uptake ( ˙VO2,max) is a physiological characteristic bounded by the parametric limits of the Fick equation: (left ventricular (LV) end-diastolic volume−LV end-systolic volume)×heart rate×arterio-venous oxygen difference. ‘Classical’ views of ˙VO2,max emphasize its critical dependence on convective oxygen transport to working skeletal muscle, and recent data are dispositive, proving convincingly that such limits must and do exist. ‘Contemporary’ investigations into the mechanisms underlying peripheral muscle fatigue due to energetic supply/demand mismatch are clarifying the local mediators of fatigue at the skeletalmuscle level, though the afferent signalling pathways that communicate these environmental conditions to the brain and the sites of central integration of cardiovascular and neuromotor control are still being worked out. Elite endurance athletes have a high ˙VO2,max due primarily to a high cardiac output from a large compliant cardiac chamber (including the myocardium and pericardium) which relaxes quickly and fills to a large end-diastolic volume. This large capacity for LV filling and ejection allows preservation of blood pressure during extraordinary rates of muscle blood flow and oxygen transport which support high rates of sustained oxidative metabolism. The magnitude and mechanisms of cardiac phenotype plasticity remain uncertain and probably involve underlying genetic factors, as well as the length, duration, type, intensity and age of initiation of the training stimulus

All that is gold does not glitter,
Not all those who wander are lost.
The old that is strong does not wither,
Deep roots are not reached by the frost.
(J. R. R. Tolkein, 1955)

A piece of string is twice as long as it is from one end to the middle

A piece of string is twice as long as it is from one end to the middle
By Wayne Goldsmith
Have you ever asked someone an open question and had them answer, “how long is a piece of string?”

Guess what?

There is an answer to this question….

And that answer is “A Piece of String is Twice as Long as it is from one end to the middle”.

And so it goes with coaching.

Experienced coaches are often asked “piece of string” questions by young coaches desperate to learn the secrets of the sport and the mysteries of the “masters”.