If you're looking to forge some major strength gains in your lower body, traditional weightlifting may not be the answer, according to research from Loughborough University. Instead, they say quick, explosive exercise is more effective.
For the study, researchers pulled together 43 healthy men in their 20s who weren't undergoing any type of physical training and hadn't completed any lower-body strength training for 18 months. The participants were split into three groups:
Group 1 (13 men): 40 1-second reps of explosive isometric (one leg at a time) knee extensions. Participants were instructed to contract their quads as hard and fast as possible.
Group 2 (16 men): 40 3-second reps of sustained isometric knee extensions. Participants were instructed to gradually increase their maximum voluntary torque* to 75% before holding the extended position for 3 seconds.
Group 3 (14 men): Control group
All participants worked out three times a week for a total of 12 weeks. Researchers monitored the participants to make sure their contractions were really explosive or sustained. They performed a range of performance and physiological measurements before and after the training to see how different contractions affected participants' quadriceps muscles. At all phases, explosive contraction work improved explosive torque* from 17-34% by boosting neural drive (17-28%); meanwhile sustained-contraction work only improved explosive torque in the late phase of the movement and increased neural drive by 18%.
*Weightlifting and strength training have more in common with physics than you’d imagine. Torque is the force that causes an object to rotate; when it comes to lifting, explosive torque is all about producing force through your muscles to support your joints and then you exert a force on an object (e.g., a barbell or piece of machinery). Think of a snatch, screwing your feet into the ground before a lift, and (in this case) making sure your muscles and joints are working together to produce the most impactful and efficient leg extension. What's more, a big part of improving torque is neural drive. This refers to how your nerves are responding to exercise to stimulate a muscle contraction. Someone untrained and inexperienced can have a huge increase in strength just by learning how to engage and use a muscle.
"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," lead study author Jonathan Folland, Ph.D., said in a press release.
The explosive contractions were less tiring and more efficient in increasing strength and functional capacity of the thigh muscles because they flip your nervous system "on," activating and engaging your trained muscles, the researchers explain.
"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," Folland adds.
However, if mass is your end game then traditional sustained exercises are best. Because slow, heavy loads put such a high stress on your body, the effort taxes your muscles and triggers hypertrophy.