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Increase the Weight or the Reps?

Q. I am about six months post RNY gastric bypass.

lifting weightsI used to be a couch potato. Now I do cardio five to six times a week and weight lifting (machines) every other gym visit. In addition to weight loss, I am trying to tone and build strength. As a general rule, is it better to increase the amount of weight lifted or to increase the number of repetitions, or both?
- Carolann

Derek Walczak, Exercise Physiologist:
This is a great question and one that confuses many gym goers. To answer it, we must first understand the relationship between training load (weight), repetitions and the training goal. First, let’s get a little technical.

Basically, the heavier the weight = the fewer repetitions one can perform in a given set. The heaviest weight one can lift for a single repetition maximum is referred to as a 1 rep max or 1RM.

lifting weightsAccording to the National Strength and Conditioning Association’s (NSCA) repetition maximum continuum, the closer you get to 1RM (lifting a heavier amount of weight), the training becomes geared more toward strength. The further away you get from a 1RM (lifting a lighter amount of weight), the training focus shifts more toward muscular endurance.

Muscular Growth
Muscular Endurance
More weight/fewer reps:
Perform 6 or fewer reps at an intensity of 85% or greater of 1RM*
Keep it about even:
Perform 6 to 12 reps at an intensity of 67 to 85% of 1RM 
Less weight/more reps:
Perform 12+ repetitions at an intensity of 67% or less of 1RM 

(Note that these are optimal guidelines and the training goals do overlap. All three training goals will still be achieved on some level no matter the load and repetitions.)

So, how does this translate to your exercise program?

Whenever you try a new exercise, you should always learn the proper form by beginning with light weight and a higher number of reps. Once this has been mastered, you can increase the weight (2.5 to 5 lb. increments are recommended) and lower the reps until this becomes comfortable. Then, repeat.

Example — Seated Row Machine

Week  Sets Reps Weight 
Week 1 10  60 lbs.
Week 2 10 to 12 60 lbs.
Week 3 12 to 15 60 lbs.
Week 4 10 65 lbs. 

The key in training for any goal is program variation. For example, if resistance training is performed three times a week, you can vary the load and repetitions in each workout. On Monday you may focus your goal on strength by performing 8 to 10 reps, while on Thursday focus on muscular endurance by lessening the weight and performing 15+ reps; on Saturday, repeat the process. This will keep your workouts fresh, and lessen the strain on joints and connective tissues while reducing the risk of an overuse injury.

lifting weightsIt is recommended to allow a day in between resistance training workouts for rest and recuperation. It is also worth noting that as you become stronger, it takes longer to recover: sore muscles groups will need up to 48 hours to recover.

So as you can see, weight and repetitions are inversely related — as the weight increases, the repetitions will decrease. Start with light weight and higher reps to master your form, and then slowly increase the weight while decreasing the reps. Be sure to vary your workouts and always give your body adequate time to rest and recover.

The NSCA recommends to never go below 8 reps for assistance exercises (single joint or isolation movements, such as the biceps curl), and fewer than 6 reps should only be attempted by those with proper training under a qualified fitness professional.

* This load and repetition assignment should only be performed with primary compound exercises (multi joint), such as the bench press and squat. Never with assistance exercises (single joint) such as biceps curl and machines.

Please consult a physician before starting any exercise program.

Derek Walczak is an Exercise Physiologist at BIDMC's Tanger Be Well Center. He holds a BS in Kinesiology from UMASS Amherst and is a Certified Strength and Conditioning Specialist through the National Strength and Conditioning Association.

Above content provided by the Weight Loss Surgery Center at Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted October 2013

Contact Information

Tanger Be Well Center
Beth Israel Deaconess Medical Center
Shapiro Clinical Center
Ground Level
330 Brookline Avenue
Boston, MA 02215

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