You open your workout, see three sets of eight goblet squats. But which weight should you grab?
You want to challenge yourself, move well, and finish the workout feeling like you trained with purpose. Maybe you’ve been using the same dumbbells for months. Or maybe you grab something heavier, get halfway through a set, and realize you’ve made a very ambitious decision.
The right weight challenges you within the prescribed reps while allowing you to maintain control and the intended technique.
That weight depends on the exercise, the workout, your experience, and how you feel that day. Here’s how to find it.
Start With the Rep Target
Your prescribed reps give you a starting point.
For the same exercise, you’ll generally be able to use more weight for six reps than for fifteen. Different exercises will also need different loads. Your squats, rows, shoulder raises, and curls probably won’t all use the same dumbbells.
If your workout calls for eight to ten reps, choose a weight that makes those reps challenging while keeping your movement controlled.
You don’t need to know your maximum lift to choose an effective working weight. Your reps, technique, and effort can guide you.
Reps in Reserve
A practical starting point for many working sets is to finish with approximately 1 to 3 good reps left in the tank.
That means you could complete a few more repetitions with the same technique, but the set already feels challenging. This is called reps in reserve, or RIR.
Here’s your weight check:
• You could do 5+ additional reps: Go heavier.
• You cannot complete the prescribed reps without swinging, excessive arching, or shortening your range: Go lighter or reduce the number of repetitions so you can maintain control.
• You finish the prescribed reps with solid technique and approximately 1 to 3 reps remaining: That is an appropriate working weight for that set.
Count the additional reps you could complete with good technique, rather than the reps you could force through.
This is a coaching guideline, rather than a requirement for every exercise. Beginners can leave more room while learning. Warmups, mobility, power exercises, and conditioning sessions may have different purposes, so follow the workout’s instructions.
Estimating your remaining reps takes practice. You don’t need to get it exactly right to start making more informed choices.
Do You Need to Reach Failure?
For this guide, think of failure as the point where you cannot complete another repetition through the intended range of motion with the required technique.
You do not need to reach that point on every set to make progress.
A systematic review and meta analysis by Grgic and colleagues found no significant overall difference in strength or muscle growth between training to failure and training without reaching failure. The findings support using challenging sets without making every set an attempt to reach your limit.
That does not mean effort is unimportant or that every approach produces identical results. How close you train to failure is one part of the program, alongside load, total training volume, exercise selection, and recovery.
Aim for purposeful effort you can control and recover from.
Challenging Can Still Look Controlled
The final repetitions may slow down. Your breathing may become heavier, and you may need to concentrate more.
That can be part of a challenging set.
Pay attention when the movement starts changing substantially:
• You swing your body to move the weight.
• Your range of motion gets shorter with each repetition.
• You lose your balance or the position the exercise requires.
• You rush through the movement to finish the set.
A challenging final repetition does not need to look effortless. It should still resemble the exercise you started.
Sharp, sudden, or increasing pain is different from muscular effort. Stop and reassess rather than trying to complete the set through it.
Use Your Warmup to Find Your Working Weight
You don’t have to guess perfectly before your first set.
For a larger movement, such as a squat, deadlift, or press, begin with a lighter practice set. Gradually increase the load as needed until you reach a weight that feels appropriate for the prescribed reps.
Warmup sets should prepare you without exhausting you.
If the exercise is unfamiliar, start conservatively. Get comfortable with the setup, range of motion, and rhythm before making load your main focus.
Your first working set gives you information too. If it is clearly too easy or too difficult, adjust the next set.
Give Yourself Enough Rest
Sometimes a weight feels too heavy because you haven’t recovered enough from the previous set.
Follow the prescribed rest periods. Before starting again, give yourself enough time to regain your breathing and feel ready to perform the movement with control.
If your repetitions drop sharply between sets, consider whether you rushed the recovery, chose too much weight, or pushed the first set harder than intended.
You may still need to adjust the load. Rest gives you a fairer opportunity to judge it.
When Should You Increase Your Weights?
Look for a repeatable pattern.
Say your workout calls for three sets of eight to ten reps. With an appropriate weight, you might initially complete:
• Set one: ten reps.
• Set two: nine reps.
• Set three: eight reps.
Over time, you build toward ten controlled repetitions across all three sets.
When you can consistently reach the top of the range with the intended technique and effort, try the next manageable weight increase. Your repetitions may return toward the bottom of the range.
That is a practical way to apply progressive overload, gradually increasing the demands of training as your ability develops.
You don’t need to increase the load every workout. Give yourself time to become more capable with the weight you’re using.
What if the Next Weight Feels Too Heavy?
Dumbbell jumps can be surprisingly large, especially for smaller exercises. If the next pair causes you to fall below the prescribed rep range or lose control, continue building with your current weight. Use smaller increments when available.
If you have limited equipment, other options may include:
• Adding repetitions within the prescribed range.
• Developing better control through the intended range of motion.
• Using a programmed pause or slower lowering phase.
• Progressing to a more demanding variation when appropriate.
Choose adjustments that fit the program. Changing the repetitions, tempo, rest, and exercise all at once makes progress harder to track.
Slowing a movement can make a lighter weight more challenging, but it does not replace heavier loading for every training goal.
Some Exercises Need Lighter Weights
A lateral raise will usually need less weight than a row. A single leg exercise may challenge your balance before the load feels particularly heavy.
Muscle size, leverage, range of motion, and stability demands all influence how much weight you can use.
Mobility and stability exercises may prioritize a controlled position or range. Power exercises prioritize quick, high quality movement and often require stopping well before fatigue changes your execution.
Choose the weight for the exercise and its purpose.
What if You’re a Runner?
Strength work can help you build & maintain strength, support running performance, and support longevity in the sport.
A systematic review by Blagrove, Howatson, and Hayes found that strength training can improve running economy and performance in distance runners. Running economy refers to the energy required to maintain a given running speed.
That gives runners a reason to progressively challenge themselves in the weight room. You don’t need, nor want, to keep every exercise light simply because you also run.
Depending on your experience and program, you might begin with a progressively loaded compound exercise, such as a squat, romanian deadlift, or rear foot elevated split squat. Then include complementary & run-specific work for your calves, hips, trunk, and other muscle groups.
Choose loads that fit each exercise’s purpose and your ability to recover.
Your strength training also needs to fit alongside your running demands, not work against it. During a demanding running week, maintaining a familiar load can be a productive choice. If your legs are unusually fatigued, use your warmup to assess readiness and adjust the session as needed.
Leaving a few repetitions in reserve is one practical way to keep sets challenging while managing fatigue. As your running demands ease and recovery allows, you may have more room to progress your strength training. View your training as different seasons, where sometimes it may be more running focused, while other times a bit more lifting focus, and sometimes right in the middle.
The goal is to build strength you can keep developing alongside your running.
Log What You Lift
Recording your weights and repetitions makes your next session easier to approach.
A useful note might look like this:
Goblet squat: 40 pounds, three sets of eight. Controlled, heavy with approximately two reps in reserve.
Now you have a reference. You can repeat it, build on it, or adjust based on how you feel.
Progress shows up differently. It may show up as more weight, more range of motion, more repetitions within the prescribed range, or better control with a load that once felt difficult.
You don’t need to leave every workout exhausted to know you trained effectively. Aim for challenging work you can recover from and repeat consistently.
Inside Commit, use the prescribed repetitions, rest periods, and coaching notes together. They help you choose a weight that fits the purpose of the session.
Choose a weight you can move well, let the set challenge you, and build from what you can repeat.
Research References
Grgic J, Schoenfeld BJ, Orazem J, Sabol F. Effects of resistance training performed to repetition failure or nonfailure on muscular strength and hypertrophy: A systematic review and meta analysis. Journal of Sport and Health Science.2022;11(2):202 to 211. Read the study.
Blagrove RC, Howatson G, Hayes PR. Effects of strength training on the physiological determinants of middle and long distance running performance: A systematic review. Sports Medicine. 2018;48:1117 to 1149. Read the study.