The easiest way to build leg muscle strength is through short, sharp contractions, according to research published in the Journal of Applied Physiology.
The study, of 43 healthy men in their 20s who had not done any previous lower body strength training, found that ‘explosive’ contractions were the least energy-intensive way of increasing strength and functional capacity of the muscles.
Traditional sustained contractions, which require more effort, are more effective at increasing muscle size but not strength.
Dr Jonathan Folland, who led the study, said: ‘The easiest way to make muscles stronger has been debated by fitness and sports professionals for many years, but this study shows that it doesn’t have to mean lots of pain for any gain.
‘Whereas traditional strength training is made up of slow, grinding contractions using heavy weights which is quite hard work, this study shows that short, sharp contractions are relatively easy to perform and a very beneficial way of building up strength.
‘These short, explosive contractions may also be beneficial to older individuals and patient groups such as those with osteoarthritis, who would benefit from getting stronger, but are reluctant to undergo tiring sustained contractions.’
This small study lasted 12 weeks and looked at three different groups. One did short, ‘explosive’ leg extensions lasting less than a second, another did sustained or slower contractions lasting three seconds. They did sets of ten following a warm-up. The third group was a control group. Muscular function and nerve function was observed pre- and post-exercise.
The clinical challenge is that patients with muscle weakness are not necessarily looking for big muscles. Instead they want to improve movement and quality of life and reduce fatigue. Therefore, traditional ways of increasing strength, such as with rowing machines or leg extensions against static weights, may not be ideal, especially if these regimes are of prolonged duration.
Strength exists in two different ways: the size and power of the muscle, but also how much of the muscle fibre we have recruited to do the work. When we use our muscles, we do not use all of the muscle fibres all the time — the amount varies. This can change according to training, usage and neurology. Sometimes muscle recruitment can be decreased, for instance in elderly people whose muscles are under-used.
The study showed that ‘explosive’ muscular contraction increased muscle recruitment and also strength to a similar degree as sustained muscular contractions. The explosive exercise group had a greater increase in the amount of muscle recruitment; maximum strength was 70 per cent of that of the sustained contraction group. The explosive exercises only took seven per cent of the time to complete, however.
This helps to explain what we already know — that a martial artist who doesn’t weight-train, isn’t muscularly large, can still deliver a powerful blow. (In this case muscle recruitment is likely to be significantly higher due to ‘explosive’-style training.)
What this offers in clinical practicality, is that low-impact, relatively high-intensity exercise regimes could be developed to aid patients who do not follow conventional strength schedules very well — those who fatigue easily, experience pain or have low muscle bulk.
This will help patients improve their quality of life without the necessity of high-cost interventions or the gym. It may be that short and sharp muscle contractions, as part of a back-garden gym routine, might be a good start for an elderly person — for example, short punches with light dumbbells for 10 to 20 seconds.