Trainer Tips: What Weights Should I Use?

Trainer Tips - What Weights Should I Use? Confused about where to start picking weights at the gym? This simple, common sense guide to choosing weights for your strength training workout makes it easy.

Last time I gave you some trainer tips, we were talking about how many sets and how many reps you should be doing in the gym. Today, I’m going to share some advice and tips for another common question about strength training – what weights should I use?

If you’re a beginner to strength training, you might take a look at the racks of dumbbells, plates and bars and have no idea where to even begin guessing at weight you should try. And even if you’ve been working out with weights for a while, you may feel like you’re not getting much training effect from the weights you’re using, or you are constantly choosing something you can’t complete your sets with.

I work with some clients online, so I can’t assess their form or strength in person. I tell those clients to use the heaviest weight they can lift for the amount of prescribed reps. That’s the simplest way of explaining something that can definitely become confusing fast.

For example, you may have seen online training plans where to the weight is listed as “70% of 1RM,” or something similar. The “1RM” is referring to the heaviest weight you can lift for 1 repetition max. If you can lift 150 pounds in a deadlift for one repetition with good form, but you fail on your second attempt (without rest), then that would be your 1RM. The idea behind this percentage based training is to work out your 1RM for major exercises like squat, deadlift and bench press, then do between 70 – 80% of that weight for endurance training, or 80 – 90% for strength training.

I don’t use that model. Here’s why:

First, it doesn’t account for range of motion. Show me ten people performing a bench press and I’ll see ten wildly different angles of their elbows from their body, as well as how far down in the range of motion their elbows bend . Range of motion will affect your 1RM greatly.

It doesn’t account for speed of lifting. How quickly you are pressing or lifting the weight will also affect your ability to maintain form throughout your exercise, as well as how much weight you can use.

Finally, it doesn’t account for genetic and psychological differences between people. Let’s say you work out your 1RM. That’s a pretty concrete stat right there – but if someone says you have to lift 75% of that weight for 15 repetitions, will you unfailingly be able to do it? The math says you will, but we humans are complex creatures and often our minds get in the way, or our muscle fibers hinder us.

Trainer Tips - What Weights Should I Use? Confused about where to start picking weights at the gym? This simple, common sense guide to choosing weights for your strength training workout makes it easy.

Here’s what I use instead – a rep scheme model. 

When I start with a client, the first couple of sessions are a little bit of feeling out strengths and challenges; trial and error when it comes to weights and load. I assess form in basic movements, as well as their ability to handle certain weights. Then I program for them based on my assessments – movements that seem challenging, or those where form needs to be corrected, I will use lighter weights than perhaps they could conceivably lift, until that form is perfected. And if a weight in an exercise seems almost too heavy, then it’s probably almost perfect. You are not going to gain strength, endurance, or training effect unless you are breaking your muscles down. It’s the repairing stage (you know, when it hurts to move) in which your muscles are actually getting stronger.

If a client can perform 10 repetitions with good form at a certain weight and to do an 11th repetition would be very difficult, or nearly impossible, then to progress the workout you would either want to lift that same weight for 11 or 12 reps the next time you train, or you would go to a slightly heavier weight and try for 10 perfect reps again.

What I think many people who are strength training don’t consider is that they should always be striving to do more, whether the ‘more’ is weight or repetitions. Just like in a marathon training plan where your long run, weekly mileage and intensity goes up every week incrementally, so should your strength training plan. Your muscles will not get stronger without a continual challenge by way of progressing your workout, either through weight or intensity.

So, what can you do to work out the right weights for you?

  • Have a plan. Write out your workouts, with your exercises and sets/reps scheme. Leave a big blank space next to those, so you can write down what weights you tried and how many reps you were able to complete.
  • Review your plan and adjust your next workout accordingly. You did a back squat with 85 pounds total for 10 reps? Next time try the same weight with 12 reps, or try 95 pounds for 10 reps.
  • Use a warm up set. If you truly don’t know what weights to try, your first set (or even your second set too) should be a warm up set. Make a guess at what you can lift, try it for the reps you want to do, then adjust the weight based on how hard or easy it was. So if you want to do three sets of deadlifts, do a ‘pre game’ set just to find out what weight is right, then do three sets at that optimal weight you’ve established.
  • Don’t compare or show off. Hopefully you already know comparison is never a good idea, but when you’re lifting heavy weights, it’s also potentially dangerous. Just because the woman next to you is lifting way more than you doesn’t mean you should try it too. Or when you feel like you need to demonstrate you belong on the weights floor – please don’t feel you need to go heavier than necessary to prove a point. 
  • Work on your form first and foremost. It doesn’t matter how heavy you can lift in a certain exercise if your form sucks. All you’re doing then is teaching your body to get stronger at sucking. Use the mirrors, get help from qualified trainers if you have access to them, check out reputable training websites’ videos and make sure you have your form perfected. Once you do, that’s when it’s time to work on increasing your weight load.
  • Listen to your body. Your body will tell you your limits and they may change depending on the time; the day; your mood; or how much rest or nutrition or stress you’ve had. Your mental game definitely plays a part in strength training, just like in running, but the sweet spot is when your mind is saying you can do one more rep, you attempt it and your muscles literally cannot push or pull the weight. 

Is this something you think about when you strength train? Do you keep progressing in your strength workouts, or do you have your set weights you use for certain exercises? I’d love to hear how you choose your weights for your workout and what has worked for you.

If you have any strength training questions, please leave a comment below or contact me via social media – I’d love to answer questions as future installments of these trainer tips posts.


  1. I remember getting this question all the time when I was a trainer. I think in all my years I lost two clan because they were disappointed after that first section ā€“ ā€“ the one evaluating strengths and figuring out challenges–they didn’t wake up unbelievably sore (?!)
    Carla recently posted…Are you sound or silence?My Profile

  2. Form is so important. It doesn’t matter how much you can lift if you are not doing it correctly. recently posted…It’s Fit HouseMy Profile

  3. So interesting!! Love this post Carly. I always thought the 1RM really was a little narrow sighted.
    Britt@MyOwnBalance recently posted…Professional Q&A: A Dermatologist’s TakeMy Profile

  4. This awesome and so helpful Carly! I always wonder if I’m lifting the right weight and how I should progress. And now I know šŸ™‚
    Christine @ Love, Life, Surf recently posted…Mirror, Mirror: On Photos and Social MediaMy Profile

  5. So helpful, Carly! I’ve been contemplating whether to up my reps or just replace my kettlebell. Now I know I should definitely aim for a few more reps at the very least – thank you!
    Laura @ This Runner’s Recipes recently posted…High Five Friday: The Mountains Are CallingMy Profile


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