The term ‘tempo’ is used to define the speed of movement of weight-training exercises. More specifically, it is the rate of movement of the weight or limb involved in any strength-training exercise. Most bodybuilders might change their exercise selection, sets, reps and rest periods, but the one variable that has been largely overlooked— and which may significantly impact training results— is the tempo or speed at which the exercise is performed.
For years, the standard repetition speed has been to lift ‘up’ or concentrically in 2 seconds and lower the weight eccentrically in 4 seconds in a slow, controlled manner for optimal muscle mass. Some top trainers have even taken this type of training a step further and developed SuperSlow training. The interesting fact is that there is no research to validate that this tempo is the optimal pace for increasing muscle hypertrophy.
According to a study published in the European Journal of Applied Physiology, lowering the weight slowly may not be the best way to increase muscle mass and strength. In the study, male and female subjects were assigned to train for 10 weeks using either slow- or fast-velocity eccentric training while lowering the weight. At the end of the study, the group who trained with fast eccentric contractions had the greatest increase in muscle hypertrophy. Muscle hypertrophy of the type IIB fibers (fast-twitch fibers) increased from 6 percent to 13 percent in those subjects. The ‘slow’ group did not experience any gain in muscle mass.1
This was not the only study to show that training with fast eccentric contractions is best for increasing muscle mass. In a follow-up study by the same research group, researchers compared fast and slow training in a group of 12 untrained men who exercised both arms, three days per week for eight weeks. The men trained one arm using a fast velocity, while they did the same number of repetitions for the other arm at a slow velocity. At the end of the study, type I muscle fibers (slow-twitch, aerobic fibers) increased in size by an average of 9 percent, with no significant difference between fast or slow training. The change in fiber area after training for the type II fibers was greater in the fast-trained versus the slow-trained arm. In addition to greater increases in type IIB fibers, the fast eccentric contractions group increased strength more than the slow contractions group.2These studies demonstrate that lifting explosively can enhance the recruitment of type II muscle fibers, which are more prone to muscle hypertrophy. What about explosive lifting, concentrically?
New Study: Explosive Weightlifting Induces Muscle Hypertrophy Greater Than Traditional Weightlifting
Researchers from Brazil conducted a new study that should raise awareness that bodybuilders need to incorporate some explosive lifting into their routine. Researchers took two groups of men and had them perform all exercises with an equal work output. The exercises were performed with rest intervals of 90 seconds between sets. The men were divided into a fast, explosive concentric group with a normal eccentric phase, or traditional weight training with 2-3 seconds ‘up’ and the weight lowered in 2-3 seconds.The explosive group performed all exercises moving the weights as fast as possible in the concentric phase, and took 2-3 seconds to complete the eccentric phase. The concentric action was performed in approximately 1 second. The traditional weight-training group spent 2-3 seconds in the concentric phase and 2-3 seconds in the eccentric phase. Here are the results of the study after 10 weeks of training: Strength: Training-induced gains in strength were similar between groups; however,explosive lifting induced significantly greater development in muscle power.
Muscle Size: Explosive lifting was more effective than traditional weight training for increasing muscle size. Both training regimens led to significant increase in arm muscle thickness; however, the results obtained by the explosive lifting group were greater than traditional weight training. Additionally, only explosive lifting was effective for improving leg muscle size.
The protocols used in the study involved the same resistance training exercises with an equal work output, and the only difference between the two methods was the speed at which the exercises were performed. It was demonstrated that a high-velocity power training program appears to be more effective in improving muscular hypertrophy than traditional resistance training.13This seems to contradict the current practice of many trainers, especially bodybuilders, who typically employ low-velocity contractions in their training.
Why Lift Fast And Explosive for Muscle Hypertrophy?
In order to induce hypertrophy, either the exercise intensity or volume must be increased. Most bodybuilders perform enough sets, but may have difficulty increasing training intensity to make additional gains in strength and size. Since the amount of weight cannot be increased, an alternative to increasing the intensity must be implemented.
Moving the weight at a higher speed implies using more power, and more power translates directly to a higher intensity. Speed training provides an alternative path to the progressive resistance principle, which states that in order to induce muscle hypertrophy, one has to constantly keep increasing the weight used. Muscle hypertrophy is defined as an increase in muscle mass that is related to two factors: the amount of workload employed and the tension developed during muscle contraction.3 Most bodybuilders focus mainly on workload or the amount of sets utilized during their training routine to increase muscle hypertrophy, seldom changing repetition speed. Speed training may develop motor unit recruitment patterns different from traditional weight training, thus potentiating better gains with subsequent regular training cycles. According to world-renowned strength coach Dr. Verkhoshansky, the tempo of resistance exercise has a significant effect on the development of muscular strength (because of fast-twitch fiber enhancement). Dr. Verkhoshansky reported that a combination of different movement tempos produce superior gains in strength, compared to a set tempo. In that 10-week study, men who trained with a combination of tempos produced a 48-pound increase in strength, but using a standard tempo pace only resulted in a 36-pound increase in strength.4 The results of the study demonstrate the importance of changing repetition speed during a training cycle.
The amount of weight lifted depends on the laws of physics. Simply, FORCE = MASS X ACCELERATION. This means the amount of force you generate during weightlifting can be increased by lifting more weight or lifting the same amount of weight at a faster speed. If you are performing the same number of reps with the same amount of weight but lifting with more acceleration, you are producing more force— and this means larger central nervous system activation. This is not a new concept. A study in 1954 by Bigland-Ritchie and Lippold demonstrated that the faster a weight is accelerated through a lift, the more nervous system activation is required for the movement.5 The more motor units or muscle fibers that are activated in a repetition, the greater the activation in the central nervous system. This represents an increase in training intensity.
During muscle contraction, motor units or muscle fibers are recruited in relation to the force generated by the muscle. For example, during slow muscle contractions, type I fibers are recruited, but as workload increases, more type IIA and finally, IIB fibers are recruited. This is a basic tenet of motor unit recruitment. What is unique about eccentric contractions is there some evidence that the size principle could be altered or even reversed during certain types of movements— specifically those that contain an eccentric (muscle-lengthening) component— such that fast-twitch motor units are recruited before slow-twitch motor units. It is possible that a preferential recruitment of fast-twitch motor units is influenced by the speed of the eccentric contraction, and can only occur using moderate to fast speeds.
When examining the potential for hypertrophy between muscle fibers (i.e., slow type I and fast type II), there are differences. In general, type IIB muscle fibers have the greatest potential for muscle hypertrophy, yet are the last fibers recruited during a lift. This is a basic flaw in the SuperSlow training principles. With low force or slow activities, type I fibers are activated first and as the exercise becomes more fatiguing, type IIA and then type IIB fibers are recruited later. When using fast explosive exercises, faster-twitch motor units are activated and more hypertrophy can occur. Hypertrophy will only occur in those muscle fibers that are overloaded, so that fast-twitch fibers must be recruited during training for hypertrophy to occur.6
Most bodybuilders do not train explosively and can benefit from incorporating explosive multi-component plyometric or speed resistance movements into their training regimen. For example, most bodybuilders experience increases in type IIA fibers during resistance training studies, with no changes in type IIB fibers.7 This may be partially due to using high-volume (i.e., 5-8 sets) and high-repetition (i.e., 10-15 reps) training. However, incorporating plyometrics and other explosive lifts may cause additional muscle growth of IIB fibers.
There have been numerous studies that have documented increases in type IIB fibers after explosive weight training8, 9and plyometrics.10, 11 When male subjects performed plyometric training for three days a week for eight weeks, this resulted in significant increases in type IIB fiber hypertrophy and peak power production. The plyometric training consisted of vertical jumping, bounding, and depth jumping.12
Type IIB fibers are utilized during high force-generating movements. Just remember, at any given speed, the force production of the muscle increases with the percentage of fast-twitch fibers and, conversely, at any given force output, the velocity increases with the percentage of fast-twitch fibers. For example, look at the thighs of 100-meter sprinters compared to distance runners. World-class sprinters have legs that would make some bodybuilders jealous. Sprinters train fast and explosively, utilizing a lot of type IIA and type IIB fibers during training, compared to distance runners— who rely mainly on type I fibers. Sprinters train in the gym the way they run… fast and explosive.
A typical sprinter trains with explosive squatting, lots of plyometric jumps, and bounding exercises. Training specificity states that you should weight train like you perform in your competitions. For example, basketball players were assigned to either train with traditional weight training or traditional weight training plus explosive, eccentric plyometrics for six weeks. While both groups had increases in their vertical jump at the end of the study, the group that trained with weight training and plyometrics increased their mean overall vertical jump by 8 percent. Thus, high-force eccentric training can possibly increase gains and muscle power by increasing muscle size.
In conclusion, many bodybuilders and fitness-oriented athletes would benefit from adding a few explosive exercises such as plyometrics to their training regimen. In competitive athletics, when all other factors are equal, power is the deciding factor between winning and losing. The ability to generate concentric and eccentric force over a range of contraction velocities is often a critical determinant of athletic success. For years, weight training was considered to slow an athlete down and make him inflexible. Fifteen years ago, the University of Nebraska started training their football team using only explosive Olympic lifts and squats. Performing explosive lifts such as power cleans, jump squats, and depth jumps recruits entirely fast-twitch motor units. The training effect produced a stronger, faster and more mobile athlete— and a winning record. Now, virtually all football teams incorporate Olympic lifts for explosive strength and power. Incorporating these movements into your training routine will increase size and strength beyond traditional weight training.
References: 1. Paddon-Jones D, Leveritt M, Lonergan A, Abernethy P. Adaptation to chronic eccentric exercise in humans: the influence of contraction velocity. Eur J Appl Physiol, 2001 Sep;85(5):466-71. 2. Farthing JP, Chilibeck PD. The effect of eccentric training at different velocities on cross-education. Eur J Appl Physiol, 2003 Aug;89(6):570-7. 3. Glass DJ. Skeletal muscle hypertrophy and atrophy signaling pathways. Int J Biochem Cell Biol, 2005 Oct;37(10):1974-84. 4. Verkhoshanskii IuV, Biru AA. Patterns in the long-term body adaptation of the athlete to physical loads] Fiziol Cheloveka, 1987 Sep-Oct;13(5):811-8. 5. Bigland-Ritchie B./Lippold O. 1954 The Relation Between Force, Velocity, and Integrated Electrical Activity in Human Muscles. J Physiol,123, 214-224. 6. Shoepe TC, Stelzer JE, Garner DP, Widrick JJ. Functional adaptability of muscle fibers to long-term resistance exercise.Med Sci Sports Exerc, 2003 Jun;35(6):944-51. 7. Jurimae J, Abernethy PJ, Quigley BM, Blake K, McEniery MT. Differences in muscle contractile characteristics among bodybuilders, endurance trainers and control subjects. Eur J Appl Physiol Occup Physiol, 1997;75(4):357-62.