Frequently Asked Questions

Why do we sometimes shake during training?

There are several reasons for the ‘shaking’ experienced during training.

The shaking that you sometimes see when someone is learning an exercise is due to the brain trying to work out how to do something new.  Just as you were wobbly on your first bike ride (as your brain worked out which muscles to use, how much, and when), you will be when learning new movements.  The more complex and unique the movement to you, the more shaky you’ll be.

You will see this when you teach people an exercise like the bench press for the first time.  It’s a relatively simple exercise once learnt but the first time you do it your brain has no real idea of what lying on your back, with a weight wavering over your face is all about.

The other reason you shake is due to energy system fatigue.  That is the nervous system is sending messages down to the motor units to contract but some of those motor units aren’t able to complete the contraction due to energy system fatigue. 

The brain quickly works this out and sends messages to other motor units to help out.  This is usually a smooth process where the demands of the exercise can always be met by the available motor units but when a large number of motor units are energy system fatigued and the brain is struggling to find help, shaking can become more and more frequent.

Note - for more information on energy system fatigue check out the energy systam folder at ptdirect.

Why do muscles hurt for days after intense training sessions?

Intense exercise that places a heavy load on the muscular system can induce what is known as ‘DOMS’, which stands for ‘delayed-onset muscle soreness’. 

DOMS is caused by lots of micro-tears in the muscle that result from the training stimulus.  Heavy repetitive loading of muscle (i.e. lots of heavy repetitions in the gym) and/or a focus on eccentric loading (downhill running with the quadriceps ‘braking’ eccentrically to resist momentum) typically produces the greatest DOMS.  DOMS normally occurs 24 to 72 hours after exercise and diminishes as muscle repair is completed.

What happens to muscle as we get older?

Muscle strength tends to peak at around 20-30 years of age after which strength tends to decline.  The decline in strength is primarily due to a reduction in muscle size caused by a loss of protein (protein builds muscle tissue and the body synthesizes less protein as we get older).

It must be noted however that the reduction in muscle size and strength with age is minimal.  The reduction in muscle strength and size with inactivity however is very large.  Have you ever noticed the wastage in muscle tissue when someone breaks a limb and has it immobilised in a cast?  Muscle tissue wastes away very quickly when it is not used.

Unfortunately as many people get older they reduce their physical activity levels.  It is this reduction in physical activity (and hence stimulus provided to the muscular system to stay strong) that is far more problematic than the loss of function associated with aging.  Essentially the old adage is true; ‘use it or lose it’!