So before the guest post by Rakhee (which spread like wildfire) my last article looked at time under tension (TUT) as our first weight training variable. If you've had a chance to go hulk style at your gym since learning about rep tempo and TUT, then you know first-hand how it can completely revolutionize your workouts. It's a weight training variable you need to consider if you want to maximize your potential. Today we'll look at a variable that most of us ignore because bro-sets and selfies get in the way, but has night and day ability to alter our progress: rest intervals.
Once again, we have varying lengths for rest intervals depending on your goals. For strength and endurance training, rest intervals are not needed to be as specific as they are for hypertrophy (muscle growth). For power and strength (between 1-5 reps), you need adequate rest for ATP (energy) regeneration and total power output, so rest intervals between 2-5 minutes are common. For endurance training (normally 15+ reps), it all comes down to trying to minimizeize rest intervals as much as possible, so 30 seconds or less is a quite common. For hypertrophy, you can probably guess, it's nestled right in the middle, 30-90 seconds.
We're after a few things when trying to build muscle: lactic acid, mechanical damage, and a hormonal response are the main ones. A rest period that ranges between 30-90 seconds allows this beautiful triage to align perfectly. Lactic acid is a precursor to muscle growth and a spark for the release of growth hormone (GH). This hormone provides a plethora of benefits outside of muscle building properties; most notably, anti-aging characteristics (ladies, I thought you might appreciate that), connective tissue building, and immune system boosting. If we allow our bodies to completely flush out the lactic acid from our muscles before continuing with the next set (a prolonged rest period), this puts one big bitch of a wrench in our potential for muscle growth. A rest period between 30-90 seconds is long enough to allow some flushing out of lactic acid (more specifically, hydrogen ions / protons) yet short enough to still have some linger for a GH response. Mechanical damage is what causes reconstruction to the muscle proteins, which allows your body to build up your muscle tissue to adapt to the stress of kicking ass and working out. A rest interval between 30-90 seconds is not necessarily required for this to take place, although anything below 30 seconds becomes difficult to lift a load heavy enough to elicit this response. The hormonal response is when we refer to badass little messengers like IGF-1, GH and testosterone. Do not worry about the acronyms, just know these little chicos are released when weight training and they just want to throw a party and help you build some lean strong muscle. The concentrations of these guys can be manipulated (increased) when controlling certain weight training variables, rest intervals being one. A hormone like GH is released primarily with hypertrophic training (8-12 reps with roughly 60 second rest intervals) while strength training (3-5 reps with rest intervals of over 2 minutes) has a higher affinity for testosterone. IGF-1 appears to be released with both training protocols if done correctly. Ladies! I need you to trust me when I say do not be afraid of the word testosterone or the role it plays in the female body.
So why does rest have anything to do with you reaching your goals? It's about the weights, not the rest … right? I've touched on why we need longer breaks (generally) for strength or power training – if you're going to do a one rep max snatch or bench press, you sure as hell better muster every ounce of energy you can. Longer rest intervals allow for 'mosting' of energy (ATP) to occur – think setting some new personal records in the gym. For endurance, our primary goal is to better recycle the lactate that's built up in our muscles, our buffering capacity, and increase tolerance of it. So it makes sense you have shorter rest intervals to try and better deal with lactic acid – think Crossfit. Those are pretty simple and straight forward, nothing too confusing about that. But what about building muscle in that hypertrophy range, why do rest intervals matter? Well, with all variables considered, this rest range turns out to be a gaping hole in a program for most individuals looking to take their bodies to air-brushed status. Assuming the rep range of 8-12 for your hypertrophy goals, a set length between 40-70 seconds, highlighting appropriate phrases of the exercise (see my last article explaining this variable here), and a 'true load' for that rep range I'll be expanding on this in my next article), these weight training variables provide a prime breeding ground for muscle growth which could have hindered if you f * ck up your rest interval.
So what rest interval should you use? Well daaaaamn boiiiii, you better be acting like fat kid in the candy store and mixing and matching all you can. But, your goals do play the primary role in determining which candy isle you should stick to the majority of the time. A good starting point is 30 second rest intervals if you're training for endurance, 60 seconds if you're training for hypertrophy (muscle growth), and 3 minutes if you're training for power or raw strength. Now let's all STFU and go build ourselves the body we've always wanted!