Warm-ups before exercise serve many purposes. At the most basic level, they prepare your body for physical activity and “knock the rust off.” Certain types of warm-ups also work as injury prevention programs, which are common in sports with relatively high injury rates. There are a few different ways to design a warm-up, each based on the priorities of the person (or group) creating it.
One of the main ways this works is by increasing the temperature of your muscles. The increased muscle temperature leads to an improved ability to use creatine phosphate and oxygen to produce energy. It also helps your muscles fire faster, allowing you to generate force quickly.
Universal warm-up vs. activity-specific warm-up
One of the first things to consider when designing your warm-up is whether you want to use one set of exercises for every physical activity you do, or have a different set for specific activities. There are pros and cons for each.
Universal programs are good when their primary purpose is for injury prevention. You’re doing the same set of exercises every time, and improve your ability to do them. Since it’s a universal program, you’re doing those exercises frequently, which gives you a better result. It’s also easier to design a universal program for a group. It creates a culture of “this is what we do before we work out” that everybody is familiar with. Over time, everyone will learn it, and it can speed up the process because you don’t need to teach something new every time. The downside is that universal warm-ups can be either fairly long or miss certain body parts. For example, you can do a thorough warm-up that covers your trunk, upper extremity (shoulders to hands), and lower extremity (hips to feet). But that can take 20+ minutes, and it might include parts that aren’t relevant to your activity (for instance, upper-extremity exercises when it’s deadlift day in the gym). Or you can have a shorter program that focuses on one body segment (for example, an injury prevention warm-up that focuses on the lower extremity). This can be for a short duration (7–10 minutes) and will probably reduce injury rates over time, but it ends up not being a great warm-up for upper-extremity dominant activities.
Activity-specific warm-ups are good for more experienced exercisers, people whose exercise programs cover different types of physical fitness throughout a week, or those who have a professional designing their workout. They can focus on the specific component of fitness to best optimize the workout. For example, a warm-up that focuses on improving hip, knee, and ankle mobility is great for lower-extremity resistance training. It’ll help you move through a full range of motion to get the most out of your lifts. Activity-specific warm-ups also can help you prepare for a 1-repetition max (1RM) test. The goal is to “wake up” your muscles that you’re about to test.
However, there are a few downsides to activity-specific warm-ups. Since they aren’t a catchall program, it’s important to plan each warm-up exercise list based on the type of exercise you’re going to be doing. Still, this can be time-consuming and challenging for beginners who aren’t familiar with exercise principles. It’s also hard to say if these types of warm-ups are effective injury prevention programs. Most of the programs in research are universal and done before most physical activities. They also have a high weekly volume of these exercises. Depending on the exercises you choose for each activity-specific warm-up, it might not be a high enough volume, or the right kind to be an effective injury prevention program.
Injury prevention
Warm-ups designed as injury prevention programs have the main purpose of improving neuromuscular control and balance. Neuromuscular control is how you coordinate your muscles during movement. It’s how well you perform the movement, not how much weight you move or how many times you can move it. Most injury-prevention warm-ups focus on lower-extremity neuromuscular control because most injuries involve the lower extremity. These warm-ups are most often universal programs—as opposed to activity-specific—and are especially common in sports such as soccer and basketball.
Muscle activation
Warming up before activity helps improve muscle activation. Muscles are made up of groups of muscle fibers that use electricity from your nervous system to contract. When you contract a muscle, only a portion of your muscle fibers fire. Resistance training—either with bodyweight exercise or with weights—improves muscle fiber activation, meaning you use a higher percentage of muscle fibers, which coordinates the movement better and makes you a little bit stronger. In addition, it helps your muscles contract faster, which means you can move more explosively. This is beneficial for power exercises such as the bench press, squat, and deadlift, as well as Olympic lifts such as the clean and snatch.
Any warm-up—activity-specific or universal—can improve muscle activation. But for heavy resistance training with loads close to 1RM (or when you’re preparing for performance tests), an activity-specific warm-up might be most effective. For example, if you’re warming up for the maximum deadlift for the ACFT, you could start off with a few sets of progressively heavier deadlifts. When you use heavy resistance training as a warm-up, it’s important to build in enough rest time to allow your body to recover its energy stores before your actual workout begins. Five minutes or so is usually plenty of time for recovery.
Ideally, your warm-up will focus on the same muscle groups that your workout will target. Progressive exercise and foam rolling your target muscle groups have both been shown to help with muscle activation and lead to slight performance increases on strength and power tests.
Improve mobility
Dynamic stretching can help improve mobility and have small performance benefits for speed and power tests. The increases in range of motion after dynamic stretching—or moving a muscle through, then slightly past a full range of motion—allow you to essentially use “more” of the muscle during exercise.
Static stretching (where you stretch a muscle slightly past a full range of motion and hold it) is effective in improving flexibility, but can actually hurt performance if done as part of a warm-up. It stretches the muscle, but doesn’t cause the temperature or activation increases that dynamic warm-ups do. The additional range of motion—without the added benefits of increased muscle temperature and activation—seems to provide no benefit to strength and power generation. In some cases, it might even decrease them.
Dynamic stretch before your workout. Static stretch after.
Bottom line
Warming up before you work out is a critical (and often overlooked) part of an exercise program. Not only will it help improve your performance during the workout, helping you get the most out of it, but it can also help reduce your injury risk over time. Be sure to do some type of active warm-up to get the blood flowing and muscles warm before any physical activity.