How fast should you move the iron when you’re weightlifting?
You can find experts suggesting everything from explosive movement to very slow movement. Years ago, a famous bodybuilder, whose name escapes me at the moment, was a huge proponent of slow lifting, but as is often the case, these assertions were just anecdotal rather than based on scientific testing protocols. More recently, however, Japanese researchers have shown that slow lifting can give great gains with less risk.
Comparing weightlifting speeds scientifically.
The Japanese researchers originally did an experiment where they had subjects do leg extensions either slowly, normally or not at all. They found that that those who slowly lifted about 55–60% of their max had similar gains in mass and strength as those who lifted 80–90% of their max at a more normal pace.
Based on that result, they decided to do a broader study that would look at exercises more like people might actually do as part of a strength training program. In this case they had subjects do squats, chest press, lat pull downs, ab crunches and back extensions using Cybex and Nautilus machines (boo hiss! We don’t like machines).
Subjects did their exercises to a metronome to ensure consistent timing. In all cases, strength gains were similar among the slow lifters and the fast lifters, with one exception. In the case of back extensions, the fast lifters had a statistically significant advantage over the slow lifters. They also had better numbers in some other categories, but not to a statistically significant level.
Both groups of lifters had statistically similar gains in muscle mass and both gained significantly more muscle mass than the non-lifting control group. In other words, doing something is better than doing nothing, and fast and slow programs gave similar results.
How slow is slow?
The researchers had their slow lifters take three seconds during the eccentric phase (that is the lifting portion in most cases) and three seconds in the concentric phase, with no rest in between reps. The fast lifters lifted at a more standard speed of one second for the concentric phase, one second for the eccentric phase, and one second pause between reps.
They note that lifting at speeds of five seconds or slower would result in lifting with weights too light to restrict blood volume and to cause lactate buildup and other factors that signal for muscle growth. So there is a point where slow becomes too slow, unless you’re working pure endurance.
The other key point is that in this context, “fast” lifting (the researchers using the term “high intensity”) is not about power generation as in the case of Olympic lifts or plyometrics. We’re talking more about standard cadence, bodybuilding style lifts versus extra-slow lifts. Neither of these is a power-building protocol.
Some key points to pay attention to
- The slow workouts are not easy. In both protocols, subjects lift to failure in eight repetitions, so they are lifting very hard, just changing the way they reach exhaustion.
- The weights are not that light. These are not the little rubber weights from the aerobics room. Again, this is a hard workout. Charts showing muscle activity in each protocol were obtained with the slow lifter squatting 75kg (165 pounds) and the fast lifter squatting 102kg (225 pounds). Granted these are not huge numbers, but they’re not that light for 8 reps either.
- These results were for untrained males. It’s not clear how well-trained athletes would respond. In general though, the body adapts to new stresses, so an athlete using a standard training program might see greater gains using a slow method because it presents a new challenge, or possibly less effect because their muscles are already trained and would not respond to lower weights. That remains to be tested.
Who should try slow lifting?
This is an open question, but some groups are definitely good candidates.
- Elderly people and people with orthopedic issues. The slow lifting program, because of the lower weights, places less stress on the joints. This makes it good for anyone with orthopedic weakness or injuries. That includes people with prior injuries and the elderly. Elderly people experience a high incidence of injury when lifting at their one-rep max because of orthopedic instability.
- People with heart conditions or arterial weakness, again including the elderly. Lifting lighter weights more slowly results in similar muscle oxygenation and lactate buildup, but dramatically lower blood pressure. The blood pressure spike caused by lifting heavy weights puts some people at risk, making the slower but lighter program safer for them.
- Athletes. As I say, there is no evidence yet about how this applies to trained athletes. We can look forward to more experiments for a definitive answer, but athletes coming off injury or who have otherwise stressed their joints might be able to use slow lifting to maintain good strength while healing their joints.
Source: Michiya Tanimoto et alia, “Effects of whole-body low-intensity resistance training with slow movement and tonic force generation on muscular size and strength in young men,” Journal of Strength and Conditioning Research, 22(6)/1926–1938