High reps or low reps - which should I be doing?

It is time, yet again, to settle another age-old debate.

Which should I be doing - high reps or low reps? Let's first dive into the physiological mechanisms of each.

High reps

When we perform exercises with high reps, it results in a build up of what we call 'metabolic stress'. In simple terms, this means there is a build up of chemical compounds in our body as the reps continue, which is a response from continuous contractions of the muscles  (Schoenfeld et al, 2021). One of them being lactic acid (which we've all heard of), which is a strong acid that actually dissociates into lactate and hydrogen ions (H+). The accumulation of H+ makes the surrounding environment acidic, which is actually the cause of that burning feeling and fatigue you feel when you're on your 15th rep! High reps can help promote strength endurance (the ability to buffer H+ and continue reps) as well as enhanced capillarisation, which allows greater blood flow to the working muscles (Campos et al, 2002). Higher reps will incur high muscle damage, which is needed in order to adapt and grow.

If you are a beginner, starting out with high reps and low load is a great way to get more practice of a certain movement/skill to build technical proficiency. It is simply more exposure, which is likely going to accelerate achieving more coordination of the movement. If you're new to squatting, it may be worth starting out with a dumbbell goblet squat at 10-15 reps, rather than risking technical breakdown, high stress on the joints (that you're not accustomed to) and potentially hurting yourself going straight to sets of 1-4 rep barbell squats near failure.

Keep in mind high reps closer to failure - a technique favoured by bodybuilders - can take a while to recover from. It will often leave you quite sore and promote peripheral (muscular) fatigue. Again, if your recovery is on point, it's a great way to build muscle. (Weakley et al, 2023)

Low reps

Low reps, conversely, are great for creating mechanical tension and increasing neural drive. 

Heavier weights close to failure recruit what are called high-threshold motor units. For example, if my max squat is 100kg and I'm squatting 40kg, my brain doesn't need to recruit all the motor units within my muscle to lift it. If I start to squat 100kg however, I have to use EVERYTHING available in my muscles, so my brain calls on ALL motor units, those last ones to be called on we call high-threshold motor units (Herda, 2022). As you can see, strength gains clearly have a high neurological component. Low rep and high load training can be quite taxing on the joints and nervous system, so it needs to be programmed intelligently to avoid risking losses in performance, or worse, injury. Maxing out every day, for example, is a great way to cook yourself! 

In terms of which exercises are suited to higher or lower reps, we recommend to hit lower reps + higher weight on big heavy compound lifts. Lifts that require a lot of joints and muscles will naturally spread the forces throughout all those joints and muscles, so you can handle more overall load safely. Examples of this would include deadlifts/back squats/barbell bench press. We generally err towards 1-6 rep efforts on these lifts (not to say you can't go more on these, but it's not that common in our programming).

Supplementary lifts and accessory exercises will be better targeted to the higher rep range. Generally speaking, they recruit smaller muscles, it's not as taxing, and in isolation the forces aren't spread among many joints, so it may not be appropriate to go super heavy (low rep). For examples of this, think single leg calf raises, bicep curls, tricep skull crushers.

Whether you choose high reps or low reps, an important thing to consider if you're trying to make strength or muscle gains is the proximity to failure. You will not increase muscle mass or gain much strength if it isn't providing stress or challenging you!  You can measure and progress this using things like reps in reserve (RIR) or rate of perceived exertion (RPE). The more trained you are, the better idea you will have of where your max is, but it is still effective for beginners. (Helms et al, 2016)

Predictably, we have concluded that neither is better or worse than the other, but some exercises will be suited to higher or lower reps depending on their joint/muscle contribution. Also, from a practical standpoint, you should probably do most of your training in the rep range that allows you to get in the most hard sets per session, per week, for each exercise you use.  This generally coincides with a moderate intensity and rep range for most exercises.

Furthermore, since different rep ranges trigger physiological responses in slightly different ways, you’re probably better off training with a full spectrum of rep ranges instead of only ever using one single rep range and intensity.

In other words, both are good, so DO BOTH!