You can change your resistance training workout by modifying a number of variables – and it’s important to do so. If you keep doing the same workout week after week and then month after month, your muscles will stop growing and your strength gains will slow.
How often should you “shake things up?” Most fitness trainers will tell you to change your routine every four to six weeks. That doesn’t mean you have to completely overhaul your workout. Simply changing a training variable will expose your muscles to a new form of stress. With new stress come adaptations and that leads to greater strength and size.
One of the many variables you can manipulate in your resistance workouts is the number of reps you do. High-rep resistance training often takes a back seat to lower rep training when you’re trying to build muscle size and strength, yet high-rep training has benefits too. Depending upon your goals, high-rep training could make up a significant part of your strategy or you could make high-rep resistance training part of a periodization scheme to help you achieve multiple fitness goals.
What is High-Rep Resistance Training?
High-rep resistance training is working with a lighter load, between 40 to 60% of your one-rep max, and doing a higher number of reps, usually more than 15 reps. With a high-rep workout, you do 15 or more reps with the load you’re lifting decreasing as the number of reps goes up. The goal is to completely fatigue the muscles. Since you’re using a lighter weight, it takes more reps to achieve this.
Lifting in this manner improves muscle endurance, the ability of your muscles to do more contractions before fatiguing. When you lift a lighter weight for more reps, you initially slow-twitch muscle fibers, also known as type 1 fibers. Slow-twitch fibers have a low activation threshold, meaning they’re recruited first when you lift a lighter weight. This is related to the size principle of muscle fiber recruitment. The fast-twitch muscle fibers are called in if the load is higher and your slow-twitch muscle fibers can’t handle the load.
Slow-twitch muscle fibers are ideally suited for light loads and high reps. That’s because they have lots of ATP-generating mitochondria to give them endurance and staying power. These fibers use aerobic metabolism, oxygen-requiring pathways to make ATP. You primarily activate slow-twitch fibers when you do low-intensity activities, like walking as well as high-rep resistance training. On the downside, slow-twitch fibers don’t have the same capacity as fast-twitch muscle fibers to generate lots of force. That’s why you need fast-twitch fibers to help you lift heavy loads or do explosive, power movements where you need to generate lots of force quickly.
So, why would you want to target your slow-twitch muscle fibers? For one, certain muscles in your body have a high ratio of slow-twitch to fast-twitch muscle fibers. For example, your gluteal muscles have more slow-twitch fibers than fast-twitch ones. To target these slow-twitch fibers, you need to do higher reps. Because slow-twitch fibers have less capacity for growth, you need to work the fast-twitch fibers in your glutes as well if you want to hypertrophy the muscle. Yet, slow-twitch fibers can also grow, so they need to be recruited through targeted training. If you never do high-rep glute work, you’re missing out on an opportunity to enhance the growth of your glutes.
High-Rep Training Can Still Increase Muscle Size
Low-rep, high load training is optimal for building strength but high-rep training can still be effective for muscle hypertrophy. A 2012 study found that lifting weights as light as 30% of one-rep max can lead to muscle growth if you do enough reps to thoroughly fatigue the muscle. It’s not just the load that counts when you’re trying to hypertrophy the muscle, volume counts too. Plus, fast-twitch muscle fibers get recruited after the slow-twitch fibers fatigue.
High reps are not completely ineffective for building strength either. You’ll get the most strength gains by doing low-rep, high load training but you can still achieve strength gains with higher reps than the standard 6 or fewer repetitions often prescribed for strength training. Strength gains diminish as you decrease the load and increase the number of reps, so you don’t want to go too light.
Muscle Endurance is Important Too
High-rep training is ideal for building muscle endurance. By lifting heavy, a high percentage of your one-rep max, you develop strength but what good is it if you can only sustain it for a few reps? That’s where endurance training comes in. Most of the activities you do, whether it’s around the house or playing sports, requires not just strength but a sustained effort. High-rep training makes your muscles capable of exerting themselves for longer periods of time. Endurance gives you more stamina when you train as well. Unless you’re doing a higher number of reps, you won’t develop muscular endurance.
Other Ways to Increase Muscle Endurance
If you’re trying to lose body fat, a circuit workout using lighter weights and high reps will increase your heart rate and boost fat burning, assuming that you move quickly from exercises to exercise with little or no rest. Another way to build muscle endurance is with isometric exercises where you hold the muscle in a state of contraction without actually moving it. An example is a plank and its variations.
High-Rep Training Helps You Avoid Overtraining
Imagine if you were to lift heavy weights every time you worked out. Using this approach, especially if you’re lifting frequently, can quickly lead to overtraining. Plus, you would eventually reach a plateau since you’re not varying the stimulus on your muscles. Periodic high-rep workouts, possibly in the context of periodized training, is a way to give your muscles a break from ultra-heavy lifting. High-rep training is not a waste of time. It’s another approach to working your muscles. Take advantage of it!
J Strength Cond Res. 2014 Oct;28(10):2909-18. doi: 10.1519/JSC.0000000000000480
Applied Physiology, Nutrition, and Metabolism, 2012. “Bigger weights may not beget bigger muscles: evidence from acute muscle protein synthetic responses after resistance exercise”
Journal of Applied Physiology, Nov 2008, 105:1454-1461.
American Council on Exercise. “Slow-Twitch vs. Fast-Twitch Training”
Related Articles By Cathe:
Related Cathe Friedrich Workout DVDs: