A rested development
This week, physiotherapist LT Rob Orr looks at maximising rest periods for muscle strength, endurance and growth.

Volume 48, No. 12, July 13, 2006

Muscle mania: Looking after your body when using weights will assist in achieving desired goals and ensure the long-term health of your muscles.

Weight training is like baking a cake; if you miss some ingredients, the results may not be all that you had hoped for.

Many muscle conditioning programs cover sets and reps, but fail to cover the key parameters which dictate the effectiveness of the sets and reps: the amount of rest between sets.

Failure to employ the correct rest time between sets impacts on the metabolic (energy) system and the nervous system. This in turn impacts on the outcomes expected when performing the given repetition range.

For example, lower repetitions are used to stimulate the large muscle fibres, through an increased activation of the nervous system. If the nervous system has not fully recovered, the purpose of the lower repetitions is diminished.
With this in mind, this article will focus on the rest times required between sets in order to optimise your gains, be they muscle mass and strength or increased muscle endurance for push-ups or a flexed -arm hang.

Some key points first. To increase basic strength there is a need to use the strongest of the energy systems and activate the largest muscle fibres by activating the nervous system to a higher degree.

For endurance, there is a need to develop buffering capacity (to counter increased H+ ions and lactic acid) and to increase the metabolic efficiency of the muscles.

For muscle mass, you need a combination of both large muscle fibre activation and a longer period of stimulation.

This means you need to determine what your training goal is, if you are to correctly apply the rest periods. Chances are you have already done this in order to select the correct repetition range. There is a strong correlation between the repetitions performed and the amount of rest required.

Strength

To gain absolute strength, low repetitions are performed, between 1–8 repetitions. The repetitions are low to allow a heavy weight to be lifted.

This means that in order to allow rest of the appropriate energy and nervous system, around 3–6 minutes rest is needed between each set. This time-frame needs to be set at rest with no super-setting (or training another muscle group while waiting) and needs to be adhered to if the desired effect is to be achieved.

Muscle Endurance

Muscle endurance training is the ability to work muscles for a longer period in the presence of increased fatigue, typically using repetition ranges of above 15 reps per set.

In order to work the nervous and energy systems appropriate to high muscular repetitions, the rest periods must be short, between 30 seconds to two minutes. This time-frame prevents full recovery of the nervous system and components of the energy system.

By limiting recovery time, training in the ‘fatigued’ zone is optimised. It is this training parameter that usually utilises super-setting.

Muscle growth

Training to increase muscle size requires both the use of the stronger energy and nervous systems in order to activate the bigger fibres which have a 40 per cent higher growth potential than the smaller fibres.

Unfortunately, unlike strength training, to grow muscle these fibres need to be kept under tension for longer. With this in mind, the repetition range typically selected for increasing muscle size is between 6–15 repetitions per set. It is for this training goal that rest must be more carefully selected.

If a training range between 6–10 is selected to focus on larger muscle fibre recruitment, then the rest period should be longer, between 2–3 minutes.

If a higher range of 10–15 repetitions is selected, to increase the duration of stimulus, then the shorter rest periods of 30 seconds to 2 minutes should be used. Again, as with the muscular endurance profile, it is here that super-setting two exercises becomes most effective.

So, in essence, just like sets and reps, the amount of rest between each set must be factored into your training protocol. Use a clock, watch or stopwatch and take control of your systems in order to maximise your potential.