A loyal (and well-informed) reader had a fairly simple #AskAmanda for me this week, but I think it’s one that bears repeating given that I consider myself a back-to-basics style of trainer.
I’ve written a few posts on the basics of weight training, where to start if you’re just coming back to exercise, and even how to train just your upper body for maximum results.
I will return time and again to the importance of fundamental movement skills – squat, lunge, deadlift, bench press, push-up, pull-up, and plank – and remind everyone to pick up the heaviest weights you can handle with good form to get the most out of each workout.

Pushups, rows, squats, and deadlifts – do ’em.
That said, one thing I’ve never addressed is what exactly makes for a “heavy” weight (sidenote: it’s also based on your age, weight, gender, body type, history, and overall goals, besides what I’m going to tell you below) and how much you should actually be lifting for the type of physique and fitness level you’re looking to achieve.

Dude on the left does LOTS of aerobic endurance work and probably does not lift. Dude on the right lifts heavy things and does lots of anaerobic work. Different types, different needs on the iron.
The short answer for “how heavy should I be lifting?” is this: for general fitness, you should lift whatever weight you can maintain for 8-10 repetitions without failure or form breakdown. If you are looking to build mass, you should lift whatever weight you can maintain for 3-5 reps without failure or form breakdown. If you are looking to build muscular endurance (say, cross-training a hamstring for running efficiency, or training your abdominal muscles to carry your posture through a long-distance cycling event), you should lift whatever weight you can maintain until muscle failure (for most people, about 30-50 reps) without form breakdown.
The longer (and more scientific, if you’re into that sort of thing) answer is to figure out your 1-rep maximum (trainer shorthand for this is 1RM) and use percentages of that maximum to train in different ways. For example:
(let’s assume your 1RM for a back squat is 50KG, or about 100 pounds)
General Fitness – 3 x 10 repetitions @ 75% (37.5 KG; 75#) with 30-60 seconds rest between sets
Muscle Build – 2 x 5 repetitions @ 85% (42.5 KG; 85#) with 2-3 minutes rest between sets
Endurance – 1 x 30-50 (to failure) @ 30% (15 KG; 30#) – one set only per exercise

A sample hypertrophy (gainz) set, working up to 1RM
Not complicated enough? Let’s go further into the dynamics of anterior/posterior chain movements. Anterior muscles are the “vanity muscles” – the ones you see on a daily basis in the mirror, such as chest, biceps, shoulders, abdominals, and quads. Posterior muscles are the “balancers” – the stuff that holds our bodies upright, such as lats, triceps, glutes, hamstrings, and calves.
Typically folks tend to overtrain our anterior (front) muscles and undertrain our posterior (back) muscles, leading to imbalances in posture, strength, coordination, and sometimes even injury. That said, our posterior-chain muscles can often carry a lot more weight than our anterior-chain (for example, right now, you can probably deadlift more than you can bench, assuming you can maintain proper form for both movements).

2 Chainz (anterior/posterior)
You can figure out your proper weight for posterior-chain movements using the same process outlined above (using 1RM), or you can use an even simpler process called ratio training. Olympic lifters (and yes, some regular people that WISH they were Olympians) use a 3:4:5 ratio in regards to bench, squat, and deadlift weights. In this example:
(assuming again that the 1RM on the back squat is 50KG, or about 100 pounds)
1RM: BENCH 37.5KG or 75# : SQUAT 50KG or 100# : DEADLIFT 62.5KG or 125#
5-REP SETS: BENCH 32KG or 56#: SQUAT 42.5KG or 85# : DEADLIFT 47 KG or 75#
10-REP SETS: BENCH 28 KG or : SQUAT 37.5 KG or 75#: DEADLIFT 47KG or 100#
Even after all this technical math, some practical advice: if your deadlift looks like crap, even if you’re using 25% of your 1RM, it’s too heavy. Similarly, if you have strong form and a commitment to actually getting stronger, lifting the same weight forever (I’ve had to talk many a female lifter out of the “baby weights brigade” to actually get their bodies to change and lose fat) won’t get you any real fitness gains.

Real talk.
And one more thing – if you’re unsure about any of this, or you simply don’t have time to take a calculator down to your workouts, bite the bullet and hire a certified personal trainer. They do all the dirty work for you, keep track of the weight you’re lifting, teach and monitor your form, and motivate you to stay accountable to a progressive program. In my (professional and of course personal) opinion, that’s worth every penny.
What are your favorite – and most effective – strength training movements? Are you confident in the weight room?