Strength athletes, who because of injury or sickness can only train with light weights, can still get a decent training stimulus out of their workouts if they make their movements with light weights slower than they would normally. A human study that researchers at the University of Tokyo suggests this.
The Japanese are looking for a training method that can help elderly people to fight sarcopaenia – loss of muscle mass and strength due to aging. Strength training with heavy weights is still the best method to build up muscle mass, but for one group of elderly people this kind of training is too risky. The Japanese want to know whether you can still build up muscle mass by using light weights.
The researchers got 40 subjects aged between 59 and 76 to train their leg muscles by using leg-extension and leg-curl machines for 12 weeks. All the subjects trained twice a week.
They used weights that were about fifty percent of the weight at which they could just manage 1 rep [1RM]. Each workout they did three sets of 8 reps, with one minute of rest between sets.
Half of the subjects trained at normal speed, which meant that both concentric and eccentric movements took one second to perform. A complete rep, including the isometric phase [where the muscles are held statically in a tensed position] after the concentric phase, lasted three seconds [LN; Normal speed training].
The other half of the subjects performed the movements at an exaggeratedly slow pace. Both concentric and eccentric movements took three seconds to perform. A complete repetition, including the isometric phase, lasted seven seconds [LST; Slow speed training].
At the end of the 12 weeks, the subjects that had trained slowly had built up more muscle mass and muscle strength than the subjects that had trained in the normal way.
How it is that slowly performed reps with light weights can have so much more effect than reps carried out at normal speed the researchers don’t understand.
They discovered that slow reps result in slightly more growth hormone being produced, and slightly less cortisol. The muscles also used slightly more oxygen when they performed slow reps.
But the effects were so small that they can’t account for the added value of doing exaggeratedly slow reps.
“Low-intensity slow-movement resistance training is effective in increasing muscle size and strength, even for older individuals”, the researchers conclude. “Since low-intensity slow-movement resistance training bears lower risk for orthopedic injury and cardiac events, this should be useful as a countermeasure against sarcopenia.”
