Having spent a lot of time in and around a variety of weight-rooms over the last 14 years there are several mistakes that seem to be universal. First, it’s always chest, shoulders, arms and ab day, no matter what day of the week it is, secondly, there are probably more barbell curls done in the squat rack than full-range squats and thirdly, most athletes and coaches neglect a simple, but complex, training parameter that can quickly improve strength gains: lifting tempo, or lifting speed.
The human body is an extremely adaptive organism and responds very well to periodically altering training variables: sets, reps, tempo and rest intervals. Changing these variables forces the body to adapt, and thus grow stronger. No change in training variables decreases the stimulation needed for muscles to grow stronger. Similar to reps and sets, the speed at which a lift is executed is often overlooked. Regardless of whether you’re training for strength or size, to maximize the training effect each phase of a lift should be appropriately manipulated and reflect the training goal of the sub-phase of training.
The training variables for each sub-phase of training should reflect the goal of that phase. Muscles need to be loaded for a specific length of time that corresponds to the training goal: 1-20 seconds for strength with little gains in muscle mass, 20-40 seconds for comparable increases in size and strength and 40-70 seconds for the best gains in muscle size with little increases in strength. Depending on the muscle group, time under tension between 50-120 seconds increases muscular endurance.
How to Read a Tempo Prescription
Before we get into why tempo is important let me explain how a lifting tempo is read. The first number of a tempo prescription is the number of seconds taken in the eccentric (lowering) phase of a lift, which is when the resistance is being lowered in exercises like the squat or bench press. This can be slightly confusing for exercises like the chin-up or curl variations because in order to lower the resistance it first has to be raised.
The second number in a tempo is the number of seconds of the pause in the stretched position, or between the lowering phase and the lifting phase of a lift. This would occur at the bottom position of a squat or when the bar touches the chest in a bench press, but would occur at the bottom position of a chin-up when the arms are straight.
The third number is the concentric phase of a lift, or when the resistance is being raised, such as when rising to the top position of a squat or when pressing the bar back to the starting position in a bench press. This is when the muscle is beginning to shorten, or contract.
The fourth number in a tempo prescription is the number of seconds spent in the fully contracted position of a lift. This would occur at the top, or lockout, of a bench press or squat before lowering the resistance for the next rep.
A 5110 tempo in an incline bench press would mean to lower the bar to the chest for a count of 5 seconds, pause the bar on the chest for 1 second (a pause does NOT mean relax, keep tension on the muscles at all times), press the bar back to the starting position for 1 second and rest 0 seconds before beginning the next rep.
The Science of Tempo
The amount of time a muscle is under tension dictates the training response just as reps and sets do. Time under tension, or TUT, affects the training response by placing different levels of tension on a muscle for a specific amount of time. The level of tension and the length of time a muscle is under tension are key factors in determining the training response. Different times under tension affect the type of muscle fibers targeted: shorter time under tension with heavy loads targets the powerful Type IIx fibers, a longer time under tension with moderately heavy loads targets the Type IIa fibers and light loads with longer times under tension target the Type I fibers (see the previous article for a quick explanation of each fiber type). Each muscle has a blend of these fibers, which is why periodically changing training variables is important for maximizing the effectiveness of a strength-training program.
For an example of how tempo can affect the training response lets say two athletes are performing a bench press with the same load for 10 reps and the training goal is to increase muscle size. The first athlete controls the weight down for 4 seconds to the chest, pauses for 1 second when the bar touches the chest, takes 1 second to press the bar forcibly back to the starting position and takes no rest before immediately beginning the next rep (a 4110 tempo). The other athlete basically drops the bar to his chest with just enough control not to crush his ribcage, taking 1 second then bounces the bar off of the chest to press the bar back to the starting position taking 1 second.
The first athlete completed the set with a total time under tension of 60 seconds (4sec + 1sec + 1sec x 10reps = 60 seconds). The second athlete took only 20 seconds to complete the set (1sec + 0sec + 1sec x 10reps = 20 seconds). Although both sets were done for the same amount of reps, the differences in the time under tension completely changes the training effect because, due to different physiological reasons that I won’t bore you with, the muscles must be loaded between 40-70 seconds in order to place enough stress on them so they will grow bigger. The load used by the second athlete is likely too heavy to control for the proper time under tension that’s required to increase muscular size and may be more suitable for this athlete to increase strength.
When training to increase strength the amount of time a muscle is under tension should typically fall between 5-20 seconds (see Table 1). This time under tension activates the high-threshold motor units, which control the powerful Type II muscle fibers. The heavy loads associated with developing strength (85-100% of the 1 rep max of a lift) increase the level of intramuscular tension, which is what stimulates strength and size gains in these fibers.
When strength levels increase through the use of heavy loads at slow velocities there is also a subsequent increase in power development due to something known as “neuromuscular efficiency.” The use of heavy loads at slow velocities teaches the central nervous system to recruit more muscle fibers in order to produce the force needed to move heavier weights, which makes subsequent phases more effective because more weight can be handled. This improvement in the communication between the nervous system and the muscles results in more muscle mass being activated to produce force. This enhanced muscle fiber activation can then carryover to produce more power: the more muscles activated, the greater the power output. The take home point is that if an athlete needs to become more powerful they first have to build a base level of strength using heavy weights at slow velocities because an increase in strength precipitates an increase in power.
Example Loading Parameters with Varying Tempos
In order to increase strength levels the muscles must be loaded for 5-20 seconds. There are many combinations of sets, reps and tempos that can be programmed to increase strength levels. While there are a number of permutations that can be followed the following chart provides just a few examples.
When training for functional hypertrophy (an increase in muscular size that correlates to an increase in strength) the optimal time under tension is between 20-40 seconds (see Table 2). There are also many combinations of sets, reps and tempos that can be used when functional hypertrophy is the training goal. The following chart provides some examples.
In order to increase muscular size the muscles must be loaded for 40-70 seconds (see Table 3). There are also many combinations of sets, reps and tempos that can be used to increase muscle size (hypertrophy). The following chart provides a couple of examples.
Like reps and sets the speed in which a lift is executed often is an often overlooked training variable. A training program is only as good as the time it takes for the body to adapt to it. Periodically altering training variables can be a very useful tool to coax the body to grow bigger and stronger. Manipulating the length of time it takes to complete each phase of a lift can be very effective at maximizing the desired training effect. Whether training for strength or size each phase of a lift should be appropriately manipulated to reflect the training goal.
For more information on program design or how to properly adjust tempos contact me at cdellasega@darisports.com.
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