A rest length is the time spent recovering until another set. Rest lengths should last long enough that tension, or the squeezing of the muscles you feel during heavy lifting, is the main factor that limits you.
If you take too little rest between sets, feeling out-of-breath and the burn caused by lactic acid may hold you back instead. These factors associate with endurance and get addressed better through intervals. Too much rest though will reduce the effect of a warm-up, decreasing muscle temperature and hurting your performance.
You should rest 1-5 minutes between exercises. You can lower this as you get in better shape but never forget the goal of creating tension. Strength and endurance do require different rest lengths. Blending them, while appealing from an efficiency point of view, can reduce the results for each.
Possible Set Rest Lengths
The rest periods you choose do affect the possible force, lactate buildup, and hormonal responses from exercise among other changes. The possible rest lengths draw upon energy systems and divide loosely into the following categories:
- Short (0-60 seconds)
- Moderate (1-3 minutes)
- Long (3+ minutes)
When using warm-up sets, you can use rest lengths within the short to moderate range. These sets aim to prepare you without feeling exhausting, so the low effort will prevent endurance from interfering with strength. Between your final warm-up set and work set for the same exercise though, stick to a moderate to long rest range. 3 minutes or more allows the phosphagen stores of the ATP-PC system, a main energy system used for heavy lifting, to recover as much as possible during the workout.
With my advice though, you will move on to another exercise after a single work set. You can therefore take a short rest period between exercises if desired, since you will proceed into the warm-up set for the next exercise after you finish working hard. This would be a more important consideration if you used multiple work sets.
Some experts suggest short rest periods for certain goals. Short rests associate with endurance though, which by nature limits tension and therefore size and strength. Short rest periods may emphasize sarcoplasmic hypertrophy but this remains unproven. Brief rest periods may trigger hormonal responses, although this effect on results is limited.
I would suggest viewing intensity on an exercise basis as opposed to a workout basis. This means you judge your success on how well you perform each lift and not on how demanding the workout feels as a whole. The body does adapt though, and some argue that once you get in shape, you can create enough tension without the other factors disrupting you. In theory, this would allow the most efficient workout. In practice, a relentless pace will limit your weights.
Strength training should be specific and separate from your endurance. Include intervals after your lifting or on other days to address endurance. This will allow each to develop best.
Use the Right Rest Lengths
Use 3-5 minutes between the last warm-up and work set but consider as low as a minute as you get in better shape if your weights stay the same. Strike a balance between too slow and too fast of a pace. Use your progress log to determine your ideal length and once you find it, stick to it.