You make the most strength gains when you lift a weight that’s 80 to 90% of your one-rep max. Lifting light weights and more reps won’t lead to significant gains in strength. Does this mean high-rep resistance workouts using less challenging weights are worthless? Not necessarily. You’ll still get benefits from high-rep workouts, although they’re not ideal for building muscle strength.
What Benefits Do You Get from High-Rep Resistance Workouts?
First, what do we mean by high-rep workouts? For a high-rep workout, you would choose a resistance that’s 40 to 60% of your one-rep max, a weight you can lift at least 15 times with good form. This is what most trainers call a muscle endurance workout – you’re training your muscles to contract against resistance for a sustained period of time without becoming fatigued.
What are the benefits of improving muscle endurance using lighter weights and more reps? For one, muscle endurance is important if you participate in certain sports or if you swim or cycle. Without good muscle endurance, your arms or legs will fatigue more quickly.
Can You Increase Lean Body Mass Using Lighter Weights?
Even though you’ll build more muscle mass by lifting heavier weights, a study published in the Journal of Applied Physiology showed it’s possible to build lean body mass using lighter weights. Researchers compared gains in muscle size using heavy weights (80% one-rep max) and light weights (30% of one-rep max). One group of men in the heavy weight group did a single set to failure while the other group did three sets to fatigue. The group lifting lighter weights did three sets to fatigue.
After training three times a week for ten weeks, all three groups experienced gains in lean body mass with little difference between the groups. The groups that did three sets had slightly greater protein synthesis, so three sets may be better than one if you’re using lighter weights. This suggests that you CAN build lean body mass using lighter weights if you lift until your muscles are fatigued.
Still, most experts will tell you you’ll ultimately get more gains in lean body mass if you lift heavier most of the time. It’s possible that over time your muscles will adapt to using lighter weights and you’ll stop getting the full benefits. If you use lighter weights to build mass, you’ll get the best results if you lift to failure. There are some drawbacks. Using lighter weights requires more repetitions, adding time to your workout.
Lighter Weights: A Plateau Buster?
One benefit of using lighter weights occasionally is to work your muscles in a different way. Your muscles adapt to even the most challenging workout over time. Adding in a few muscle endurance workouts helps to prevent plateaus. You can enhance the benefits of high-rep workouts by choosing a weight that’s not TOO light. You’re not going to get benefits using weights that are 20% of your one-rep max. Choose a weight that fatigues you after 20 or 30 reps max.
You can also increase the benefits by slowing down the speed of each exercise to hold muscle tension longer. Try doing the concentric or lifting movement at the normal speed and the eccentric or lowering phase as slowly as possible. Even if you’re using a lighter weight, don’t be surprised if you feel sore over the next few days.
High-Rep Resistance Workouts Help to Prevent Overtraining
High-rep resistance training, like my High Reps DVD, using lighter weights is a good training option when you’ve done several sessions of heavy strength training and your muscles could use a break. They’re an opportunity to let your muscles rest and recover from strength workouts.
You can also alternate lighter weight sets with cardio in a circuit-style manner to burn fat, boost muscle endurance and improve cardiovascular endurance when you’re short on time. Lighter weights work best for circuit workouts in many cases anyway.
The Bottom Line?
High-rep resistance training does little to build strength but that doesn’t mean it doesn’t offer benefits. There is some evidence that you can build lean body mass using lighter weights if you lift to near failure, but you’ll likely get better results if you combine lighter weights during some sessions with heavier weights you can only lift for 8 to 10 reps. At the very least, working with lighter weights improves muscle endurance and helps to prevent training plateaus. If you train with lighter weights, choose your weight carefully. You’re going to need more than 2-pound weights to get benefits.
WebMD. “High Reps With Low Weights Builds Muscle, Too”
Journal of Applied Physiology July 1, 2012 vol. 113 no. 1 71-77
Men’s Health. “Build Muscle with Light Weights”
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