Rest Intervals – The Forgotten Secret to Success
One of the most neglected training variables considered when designing weight training programs is rest. Reps and sets? Check! Weight? Check! But when was the last time you saw someone in the gym looking at their watch or smartphone to determine when to start their next set? This is a shame, especially when you consider how rest periods can influence your results.
Consider the following exercise prescription: Lunge: 5-8 reps x 5 sets, 3011. What is the purpose of this workout? Is this designed to increase strength, muscle mass, or muscular endurance? We don’t know because the rest intervals are not shown that determine if we have complete or incomplete recovery between sets. Expanding on this idea, here is the same workout designed with rest intervals and the specific fitness quality they develop:
Lunge: 5-8 reps x 5 sets, 3011, rest 240 seconds
Lunge: 5-8 reps x 5 sets, 3011, rest 90 seconds
Lunge: 5-8 reps x 5 sets, 3011, rest 30 seconds
The reason each of these protocols have a different training stimulus is that the longer rest intervals enable you to use more weight, thus increasing the intensity. If your best lunge for 8 reps is 100 pounds, for example, if you only had 30 seconds rest between sets you might only be able to use 70-80 pounds due to fatigue. With 240 seconds rest, you should be able to stay within the 5-8 rep range for several sets equaling (or slightly less than) 100 pounds. However, the plus side of shorter rest intervals is that they produce a hormonal response that can more strongly influence fat loss. This is why programs such as German Body Comp use shorter rest intervals, usually 30 seconds or less between sets.
Getting more specific, here is what you need to know about how rest intervals affect your training.
For developing maximum strength, which generally involves using weights that are 80 to 100 percent of the 1-repetition maximum, you want to rest long enough to allow the nervous system to achieve near complete recovery, but not so long that you reduce neural activity (which will reduce the amount of weight you can use on your next set).
Depending on the exercise, complete recovery between sets takes about four to five minutes. For isolation exercises, such as a preacher curl or dumbbell lateral raise, three minutes is usually enough. For compound movements, such as a squat or deadlift, every second of a five-minute rest period is appreciated. In fact, in the sport of weightlifting, often coaches make several changes in their athlete’s competition attempts. The clock has to stop when a change occurs, and this short break gives their athletes a few precious seconds to recover from their previous attempt.
Another factor influencing rest periods is the level of strength. Someone who bench presses 500 pounds would need more rest time between sets than someone who only bench presses 150 pounds. Associated with strength is the muscle fiber composition of the individual. Someone with a higher percentage of slow twitch fibers may be able to get by with less rest than someone with fast twitch fibers. How do you determine your muscle fiber type (without subjecting yourself to painful muscle biopsies)?
A practical way to determine if you are fast or slow twitch for an exercise is to perform as many reps as possible with 80 percent of your 1-repetition maximum. If you do 7 or fewer reps, you are predominately fast twitch for that exercise; if you do 12 or more, you are predominately slow twitch: and reps of 8-11 would indicate an even split. One of the most dramatic differences for this test can be experienced by comparing a leg press with a leg curl. It’s not uncommon to perform twice as many reps with submaximal weights with the leg press (as the quads have a higher percentage of slow twitch fibers compared to the hamstrings).
One downside of needing additional rest time to allow for adequate recovery is that it can make workouts exceptionally long. There is a way to get around this issue by using a type of circuit training called supersets. With supersets, you alternate two exercises for opposing muscle groups, provided you keep the total rest time between sets (which includes the time it takes to perform the exercises) for the same movement the same. Take the following two examples:
A. Seated Military Press: 6 x 4, 3010, rest 240 seconds
B. Wide-Grip Lat Pulldown: 6 x 4, 4010, rest 240 seconds
A1. Seated Military Press: 6 x 4, 3010, rest 90 seconds
A2. Wide-Grip Lat Pulldown: 6 x 4, 4010, rest 90 seconds
To be clear, the superset workout would proceed as follows: set 1 of A1, rest 90 seconds; set 1 of A2, rest 90 seconds; set 2 of A1, rest 90 seconds, set 2 of A2, rest 90 seconds, etc. This protocol was examined in a research paper published in the September 2011 issue of the Journal of Strength and Conditioning Research.
The study lasted eight weeks, had 33 subjects, and involved one group using traditional weight training protocols and the other using circuits. The circuit training group finished their first workout in 55 minutes compared to 105 minutes when performing 3 sets, and in 78 minutes compared to 125 minutes when performing 6 sets. The researchers found that both training groups achieved the same results in maximal strength and increases in muscle mass, but there was a bonus with the circuit training group as they experienced significant decreases in bodyfat.
Unfortunately, many of the workouts that appear in fitness magazines don’t address the issue of rest intervals. Don’t make this mistake! Determine your training goals and prescribe the appropriate rest intervals to help you get the most out of your training.