The acute training variables that may be manipulated to reach the specific goals in each phase of training are comprised of repetitions, sets, training intensity, training volume, repetition tempo, rest interval, exercise selection, exercise order, training duration and training frequency. (NASM) Because the body is very adaptive and will increase its efficiency when faced with the same stimulus over and over again, these variables must be changed on a regular basis in order to keep the body stimulated and improving.
Repetition tempo refers to the speed at which a repetition is performed. Understanding that functional movement occurs in all planes of motion and includes a deceleration (eccentric), stabilization (isometric), and acceleration (concentric) phase is important. The total time the muscle is contracting is called time under tension and can be manipulated for specific results. Manipulation of these phases of tempo for goal specific results is known as the Repetition Tempo Continuum. For endurance training repetition tempo should be slow with an eccentric (negative) of 4 seconds, a isometric phase of 2 seconds, and a concentric (positive) of 1-2 seconds. For Hypertrophy training tempo should start slow and work to a moderate tempo with eccentric (negative) of 3-1 seconds, isometric of 2-1 seconds, and concentric of 1 second. Strength should include a moderate tempo of 1 second for all phases of contraction working into a power tempo which is as fast as safely possible, as power incorporates a component of speed. In order to safely and efficiently progress with minimal risk of injury, “one must utilize the entire repetition tempo continuum to achieve results.” (NASM)
Rest interval is another of the training variables that can be manipulated for specific results. Rest interval refers to the time between exercises. The amount of time between sets/exercises can have a dramatic effect on the outcome of a training program because it can alter the bioenergetic continuum (type of energy being used). For example, a 30 second rest interval will replenish about 50% of the ATP/CP stores, the energy the muscles use to perform work. This means that shorter recovery intervals between sets will leave you with less energy available for the next set, leading to increased lactic acid accumulation (from anaerobic metabolism) causing “fatigue and loss of neuromuscular control.” (NASM) It is easy to understand how inadequate recovery can decrease performance and lead to increased risk of injury. Conversely, a recovery period that is too long can decrease body temperature and neuromuscular activity increasing the risk of injury. Appropriate recovery periods are dependent on the goal of the training program. Part of the adaptive process that occurs when someone exercises includes improvement in the efficiency of the systems that allow one to recover after performing work. This means people who have been working out longer typically recover faster, however individuals with larger muscle mass will require longer rest intervals, as they consume a larger percentage of their energy stores. A recovery period of 1:2 (work:rest) is typical for cellular change (endurance/hypertrophy) and a rest period of 1:5-1:12 (work:rest) is common maximal strength and power. If time frames are confusing, consider using heart rate recovery as an indicator of when to perform your next set. Typically adequate energy store replenishment has occurred by the time ones heart rate has returned to 110-120 beats per minute.
To summarize, there are many variables that may be manipulated to achieve specific goals and keep your body challenged and attaining results. Tempo and rest interval are two of those variables and provide powerful tools for program design and composition. If you find yourself doing the same number of sets, reps, at the same speed with the same recovery in between sets, chances are you find yourself achieving fewer results.
Tags: Body Change, Rest Interval, Tempo, Workout
