How Long Should Rests Between Sets Be?
The Forgotten Training Variable
Out of exercise selection, exercise order, sets, reps, tempo; rest period, and load the rest period is probably the least cool of the bunch! How come? Many people don't realise this requires any consideration at all.
How much you rest has MASSIVE implications on how effective your resistance e training is. You really can’t just say: increase the rest period to increase the weight. What you're aiming to achieve with your training will mean that specific rest intervals will be required to attain your desired outcome.
Rest Periods 101: The Science
Scientifically...
Long rest intervals (2-3 min) improve bulk and strength gain, especially with compound exercises. Long rest intervals enhance stress and tissue damage, improving development.
Short rest intervals (1 min+) improve GH and IGF-1 secretion. Lactate production rises, which helps grow muscle by increasing follistatin, myogenin, and reducing myostatin. Muscles release myostatin, which inhibits growth. Lower output boosts growth.
Higher repetitions (12-25+) and shorter rest periods enhance lactate secretion.
Growth hormone (and presumably IGF-1) only rose during the first month of resistance training, then returned to rest period values. Short-rest interval training blocks may be beneficial.
Shorter rest periods raise cortisol and adrenaline. Limiting your slumber might initially energise you. This might assist you start your exercises and warmup sets, but too much can burn you out.
When nearing your one-rep max, longer rest periods lessen mental fatigue and cortisol production. When exercising near-max or max effort for sets of 1, 1 minute rest is enough for performance, but 3-5 minutes respite reduced cortisol better.
Shorter rest times enhanced strength-endurance (the ability to execute more repetitions with a moderate weight or recover quicker between sets).
This is related to set reps. Higher reps/shorter rest improved resistance in studies. Shorter rest and higher repetitions (12-25+) may improve muscular resistance more than low-moderate reps (1-8ish) with extended rest intervals.
Muscle Growths Two Pathways
I want to take a quick tour on how we apply rest intervals to your training. The two predominant pathways of hypertrophy are:
The Mechanical Pathway
The mechanical pathway refers mechanical stress which is imposed on the muscle fibres by lifting as heavy as possible for a given amount of reps. This is about creating a high amount of tension via stretching muscle fibres to create micro-tears and mTOR responses.
You achieve greater amount of micro-tears and MTOR activation when you maximize tension and lengthen the muscle simultaneously. When looking to achieve growth this is deemed as the most efficient way to conduct a rep.
You also require adequate amount of reps in your set to achieve maximum effectiveness. Low reps per set from 1-4 produce a significant amount of damage per rep by way of the high amount tension, however there are not enough reps per set to stimulate maximal growth .
The mechanical pathway is best suited to going for sets of 5-12 reps. It creates enough tension via having enough load required to cause muscle trauma but allows you get enough reps due to not being as heavy at the 1-4 reps range.
Remember that while you keep tension on the muscle you need to move through as much range of motion as possible. You'll only ruin the effectiveness of your training by releasing the tension through your rep (eg lowering the weight too fast)
The Metabolic Pathway
When we lift weights and exert our muscles we secrete chemicals like growth hormone, IGF-1, MGF, and lactate which have anabolic properties, and this is the basis of the metabolic pathway to muscle growth.
Lactate accumulation is a fundamental element of this pathway. That pesky muscle growth limiter myostatin is actually lowered by lactate. GH and IGF-1. also get boosted my lactate build up.
You start to accumulate significant amounts of lactate when your sets run for about 40 to 70 secs. With this method don't think of the load and full range of motion as such an important factor so long as the set is significantly challenging all the way through to the end. In fact, to keep the muscle under constant tension shortening your range of motion can be helpful in many instances.
to put this in practice the lower third of a dumbbell lateral fly has nearly no tension. To increase lactate build up Its actually optimal to avoid lowering the dumbbells all the way down. Lactate accumulation is stifled when muscles relax, as it then can depart the muscle (and be brought to the liver).
Hypertrophy Pathways and Rest Intervals
The mechanical pathway is tied to the amount of weight you use. Provided you keep full range of motion is the set the more weight you us means more tension and more muscle damage. Which that in mind longer rests between sets are the best way forward. Longer rests allow you to fully recover and maintain more weight from set to set. If you don't fully recover it will make you reduce the load from set to set, decrease the effectiveness of the following sets in regards to muscle damage/mTOR activation.
While using the mechanical pathway, you must…
Use multi-joint movements, or the exercise that allows you to use the most weight.
Use the fullest range of motion possible.
Keep the eccentric/negative under control to maintain the tension throughout the whole range.
Use longer rest intervals. Three minutes is the norm. Go up to 4 minutes for more demanding exercises (squats). Decrease the rest interval a bit for less stressful movements (pulley or machine exercises).
For the METABOLIC pathway, the load used is not as crucial. Here you are trying to build up as much lactate as possible with each set.
When you use this pathway, you must…
Use more isolated exercises where you can really focus on flexing a specific muscle.
Keep the tension. If you release tension, blood can come out of the muscle, bringing lactate with it and making it harder to accumulate.
Use shorter rest intervals. If you rest only 30-60 seconds, you won’t clear out all of the lactate produced in the preceding set, making it easier to accumulate it on your next set.
You usually use more isolated movements with the metabolic pathway, this circumvents the impacts of higher cortisol secretion from the lower rest intervals.
The use of isolation or machine exercises also works around the problem to under recovering from shorter rests which impede motor control.
The Positives and Negatives
Positives of Extended Breaks
Enable you to perform heavier lifts
Reduced levels of the stress hormone cortisol
There will be less mental fatigue
Reduced potential for skill deterioration and harm
Negatives of Extended Breaks
Cause a loss of drive or pull you out of the flow state
Possibility of elongating time spent exercising
Reduced metabolic hypertrophy pathway efficiency
Positives of Having Shorter Breaks
Promotes the buildup of lactate and the synthesis of more growth hormone and insulin-like growth factor 1.
A further increase in resistance may be possible.
Gets you pumped up; improves your focus.
Keeps your workouts concise and efficient
Possible fat loss benefits from elevated GH production and cortisol/adrenaline levels.
Negatives of Taking Short Breaks
Makes it harder to keep going from one set to the next, especially in the middle range of reps (5-12)
Increase the accumulation of mental fatigue
Accidents and a decline in skill level are more probable.
It raises cortisol, which might be problematic during high-volume exercise.
