A muscle strain—also called a pulled muscle—occurs when a muscle is stretched beyond its normal capacity, causing the muscle fibers to tear from the tendon. It is one of the most common injuries in sports and physical training, so it would behoove us to learn what causes a muscle strain and how we can prevent them from happening.
To get a good understanding of how muscle strains occur, we should familiarize ourselves with the structure of a muscle. Every muscle is surrounded by an outer sheath that contains bundles of muscle fibers, which in turn are surrounded by an internal inner sheath. When the fibers link and slide together, the muscle shortens and contracts. When they slide apart, the muscle lengthens and it relaxes. Contraction causes the joint the muscle is attached to to move in one direction, lengthening causes it to move in the opposing direction. Our central nervous system tells the motor units within a muscle whether to contract or relax, which is what allows us to perform complex movements such as a clean and jerk.
How muscle strains occur
When muscles become overloaded and are asked to perform more than their capable of (as a result of fatigue, inflexibility, tightness, weakness, sudden movement or poor mechanics), the muscle fibers tear from the tendons that attach to the muscle. For example, calf strains occur when the foot quickly bends upward, stretching the muscle and causing a tear. This is typical in sports like sprinting (coming out of the blocks), long and high jump and sports that require sudden change of direction. Strains can also occur during sustained eccentric contractions. The eccentric portion of a movement is the period where the muscle lengthens, such as the lowering phase in a squat or deadlift. This is why athletes are susceptible to muscle strains towards the end of workouts, as the muscle is fatigued and therefore doesn’t have the ability to produce enough force to stop the fibers tearing from the tendon.
Muscles that are susceptible to strains
The hamstrings are at risk of strains in sprinting when the foot is about to make contact with the ground, as this is the point where the muscle is most stretched. The same is true for the deadlifts as the bar passes the knees on its descent to the ground. Hip flexor strains are common on the opposite side of the stride, where the foot is leaving the ground to move forward. Muscles in the back are at high risk of straining and tearing when they lose their static tension (also known as isometric contraction, when the muscle length doesn’t change) during squats and deadlifts as they become fatigued, causing the lower back to round.
Depending on their severity, muscle strains are placed into three different categories:
Grade 1 Strain
Some damage to a small number of fibers, requires up to three weeks of rest and recovery. Symptoms for a Grade 1 strain include pain in the soft tissue, typically during the eccentric portion of movement. There is minimal swelling and no bruising.
Grade 2 Strain
More muscle fibers are damaged, but the muscle is not completely ruptured. The recovery period typically lasts between 3 -6 weeks. Expect to experience some swelling and bruising, as well as pain during concentric and eccentric movement. Range of motion will also suffer.
Grade 3 Strain
This is a complete rupture of the muscle that will most likely require surgery to fix, with rehabilitation time around 3 months. Swelling, bruising and pain are all symptoms of a Grade 3 strain—as well as a visible gap in the muscle where it tore in two (lovely). If you’re unfortunate enough to have this happen to you, ice the injury, keep it elevated and get to an emergency room as soon as possible.
It’s important to recognize when you have a muscle strain and take the necessary steps to allow the muscle to heal. If ignored and left untreated, a Grade 1 strain can develop into a Grade 2, or possibly even rupture.
Preventing muscle strains
Some muscle strains can’t be prevented, but you can take steps to lower the chances of getting one during a workout.
Warm up properly and perform dynamic stretching
Dynamic stretching involves stretching muscles while moving, gradually increasing reach, speed or both. Unlike static stretching, where there is a neuromuscular inhibitory response and muscles actually become less responsive, dynamic stretching actually activates the muscle and increases body heat and blood flow in preparation for an activity. Increased muscle temperature allows muscles to contract and relax more quickly, allowing for enhanced speed and strength gains. Increased blood flow increases the amount of oxygen available for working muscles, allowing for greater endurance and performance gains. Examples of dynamic stretching include leg and arm swings that gradually increase in range of motion.
Perform eccentric strength training
If the eccentric portions of a lift or movement are when the muscle is most likely to become strained, then we should train our muscles to maintain their strength and tension while they are lengthening. You can do this by altering the tempo in certain portions of a lift to strengthen the muscle throughout the eccentric phase. For example, during a deadlift lift the bar from the ground at normal speed. But take three seconds to lower the barbell, and feel how much your hamstrings and lower back are working to maintain tension and keep your body in mechanically efficient positions. Perform tempo lifts at weights that are well below your 1-rep-max to avoid injuring yourself. You can also negative weight training. Negative weight training is traditionally done by power lifters who are accompanied by spotters to help them with the concentric portion of the lift. Since you’re capable of lowering far more weight than you lift, the idea behind this method of training is to overload a bar with more weight than you can lift for two or three reps of the movement, and perform the eccentric portion of the lift. When you reach the bottom position, your spotters step in to help you lift the bar through the concentric phase. Negative reps promote increased control over the weight, which will benefit technique, as well as increasing muscle strength and size.
Always prioritize form
CrossFitters have a tendency to forgo mechanics when racing against the clock and approaching the end of a metcon. But since most of us are not competitive athletes looking to make it to the Games, it’s not worth allowing our lower backs to round or our chests to cave forwards in the name of shaving a few seconds off of our times. When you start to feel like you are losing good body position during a workout, drop the bar and rest. If this happens continually, then lower the weight until you’re confident that you can handle heavier loads with proper mechanics for longer periods and when you’re fatigued. Moving smoothly with control is the best way to prevent a muscle strain, as a sudden jerking motion (which usually happens when other muscles have to compensate for ones that are weak or fatigued) can easily lead to excessive muscle fiber tears.
Photo courtesy of Josefina Casals/CC BY NC ND 2.0