How much is enough?

As a physiotherapist one of the most commonly asked questions asked in relation to exercises is: “How many should I do, and how often?”

Good exercise prescription is not just about providing suitable and appropriate exercise to address an issue or prevent a problem, but also the correct advice on frequency and duration of exercises. Despite what some may think, or how it may appear, there is actually a science and reason behind how many and how often in regard to repetitions (reps) provided. In the same way that a doctor may decide on how many tablets and how often they prescribe you to take them.

Following an assessment, a physiotherapist will advise you on whether the issue is around building strength for power, or stamina and endurance. This will relate to the role and action of the muscles needed to develop.

So what is the difference?

Strength is in the ability to perform activities that require physical (or mental) effort. In relation to muscles, strength relates to the amount of force a muscle can produce with a single maximal effort.

Power is proportional to the speed that maximal contraction or force can occur. i.e that which we see as a quick blast. In other words on one rep what is the fastest, hardest contraction one can achieve.

eg: A Sprinter out of the blocks

Endurance is a specific form of strength. This is also known as stamina and is the muscles ability to repeat the contraction for long periods of time before it becomes fatigued (or exhausted).

What would be required for a marathon runner

Why is there a difference?

Muscle fibres within the muscle govern the action of a muscle and how effective a muscle is, or can be, at its job. Muscle fibres are broadly based into slow twitch and fast twitch. These are what govern the ability of a muscle to create a quick powerful bursting action (fast twitch) or to provide a longer lasting endurance (slow twitch) of activity

Fast twitch fibres are those which are able to contract quickly and rapidly but will also tire quickly. The “speed” activators. The muscles which contain large amounts of fast twitch fibres are those which help us move quickly. eg jumping to catch a ball, running to the bus, reacting to a trip or fall. These muscles are the ones that are able to support us to stabilise and balance.

Slow twitch muscle fibres are those are able to contract develop their force and then relax slowly and repeatedly, thus allowing the body to continue an activity for long periods of time. These muscle actions require combined training with breathing control to achieve maximum benefit, to ensure a good rich oxygenated blood supply to these muscles.

The reality is that most muscles combine fibres of both types and as a result are able to develop the ability to work in either form, especially when trained. However with poor utilisation of fast twitch fibres they will convert to become slow twitch, more endurance based fibres, therefore reducing the reactionary power function. This can be reverted with correct training though!

How do I know which to train?

Your physiotherapist will, after assessing you will be able to ascertain which muscles require training and in which way, although you probably know whether you are a sprinter or an endurance athlete yourself! How many reps and how often should I train?

As in a lot of research, there is no one direct answer and part of the judgement around correct number of reps and frequency will be determined by your physiotherapist. In relation to the research, your current level of ability,injury, goals, and other life factors!

The general principles and research data however suggest that if you are training muscles for power then 8-12 reps is the ideal with 2-3 sets using the appropriate level of resistance, until the muscle is fatigued. This may be using body weight, gravity, weights, or rep band as your resistance. This does not mean 30 reps straight off, but 3 sets of 10 with pauses in between, to allow muscles to work at their maximal force. For endurance training the current data ranges suggest that 2-4 sets of between 12-25 reps is the ideal, working muscles to fatigue (this is difference to pain!).

Don’t forget though muscle training is not a quick process! Muscles do not develop and produce super-duper highly functioning muscles overnight. Strengthening muscles relies on not just the muscle fibres but the neuromuscular system working and increased neural recruitment and neuroplasticity (getting the brain to change as well and send the correct message to the muscles about what to do too!). For this reason it is usually around 6-12 weeks to see real, true gains in strength training.

So whether you are looking at training to be the next Mo or Usain, or simply want to correct any underlying muscle inactivity, or merely prevent future injury it is worth being assessed by your local friendly physiotherapist who can assess your power, strength and endurance and therefore provide you with the programme most appropriate to you and your muscle's requirements.