Identify & Fix Muscle Imbalances & Injury Risks

Galpin highlights that plyometrics are one of the most studied interventions in the asymmetry literature. A review of eight randomized controlled trials with about 150 participants found that unilateral plyometrics (jumping and landing on the same leg) almost always significantly decreased asymmetry, whereas bilateral plyometrics were less effective. The key difference is that unilateral landings force the athlete to control the entire body—hip, shoulder, neck, posture—through the torso, creating a balance and stability challenge that goes beyond local muscle strengthening. This engages more of the nervous system, enhancing coordination and reducing the bilateral force deficit. In contrast, slow, light corrective exercises or traditional strength training often fail to address the neurological and coordinative aspects of asymmetry. Galpin also notes that this approach is particularly relevant for symmetrical sports where even small asymmetries in force production or ground contact time can significantly increase metabolic cost.

Galpin prefaces this 5-step program by stating there are zero high-quality RCTs showing that correcting a specific asymmetry percentage reliably prevents injury. Thus, this protocol is his synthesis of conversations with D1 strength coaches, physical therapists, and scientists, combined with his own coaching practice. Step 1 (pre-exercise) involves foam rolling or mobility work to ensure the joint can achieve a symmetrical position, followed by activation drills specifically on the weaker side to 'turn on' the muscle. Step 2 (exercise selection) recommends swapping barbells for dumbbells to allow independent limb work, and individualizing exercises—if a standard glute bridge doesn't activate someone's glutes, find a variation that does. Step 3 (technique) emphasizes removing distractions (no music/podcasts), using verbal cues, and incorporating slow tempos or isometrics to expose and correct compensations. Step 4 (programming order) starts with heavy bilateral compounds to build overall strength, then moves to unilateral work beginning with the weaker side, and optionally finishes with isolation work. Step 5 (volume) is the 'big kicker'—accumulating more work for the lagging side through extra reps, sets, or a dedicated finisher set to failure. He also recommends doing mobility work during rest intervals rather than dedicated long stretching sessions.

Galpin dedicates a significant portion of the episode to hand grip asymmetry, noting he found over 25 studies on the topic in the last 5 years alone, many from Ryan McGrath's lab. Around 50% of the general population has >10% grip asymmetry, and this climbs to 75% in older adults. The asymmetry is predictive independent of absolute grip strength. Specific findings: a 0.1 increase in asymmetry ratio is associated with a 26% increased likelihood of falling; >10% asymmetry is linked to 2–3x increased risk of sarcopenia; and it predicts cognitive disorders, walking speed, cardiovascular disease, respiratory disease, cancers, COPD, and multi-morbidity. Mechanistically, grip asymmetry may reflect underlying neurological health—one study found that plasma neural cell adhesion molecules (a marker of neural damage) were 20% higher in those with >10% asymmetry. Galpin argues that while grip strength is sometimes overhyped, grip asymmetry is a distinct, underappreciated signal that is easy and cheap to measure. He recommends using it as a screening tool, not as the sole focus of training.

Galpin notes that among functional tests, unilateral jumping has some of the strongest evidence for predicting injury. In his review, five of six studies found a positive association between single-leg hop asymmetry and future lower-body injury. He contrasts this with movement screens like the FMS, which have mixed evidence. The hop test is valuable because it involves high force, speed, and coordination, exposing asymmetries that might not appear in slower or lighter tests. However, he cautions that athletes who specialize in unilateral jumping (e.g., basketball players who always jump off one leg) will naturally have larger asymmetries, and those may be sport-specific adaptations rather than injury risks. For symmetrical sport athletes (runners, cyclists, powerlifters), asymmetries in hopping should be taken more seriously.

Galpin explains that the FMS has mixed research support: some studies show it predicts injury, others do not. He argues that when you contextualize the research, it makes sense—if someone scores very poorly (a 'D' or lower), they likely have movement quality issues that increase injury risk. But moving from average to excellent on the FMS probably doesn't change injury risk because the test doesn't challenge the system enough to reveal subtle asymmetries. Highly trained athletes often score well on the FMS because they can compensate for asymmetries with skill and strength. Therefore, Galpin uses the FMS as a low-level screen to catch major problems, not as a precise asymmetry tool. For more detailed asymmetry assessment, he prefers morphology imaging or loaded functional tests.

Galpin shares that he has used this strategy for years with athletes and non-athletes. He finds dedicated 20–30 minute mobility routines less effective and harder to adhere to. By inserting mobility work into rest intervals, the athlete gets frequent, low-dose exposure to the desired range of motion without adding time to the workout. He acknowledges it might cost a bit of strength or power on the next set, but if the primary goal is correcting an asymmetry, that trade-off is worth it.

Galpin explains that fat infiltration compromises contractile tissue—where myosin and actin should be, fat sits instead, so the muscle cannot produce force even if it looks large. This fat accumulation is often a consequence of a previous injury that wasn't fully rehabilitated. He shares the story of Doug Larson, who had a 45% smaller hip muscle on one side with 25% fat infiltration versus <5% on the other, traced back to a hip dislocation a decade earlier. The muscle had never properly reattached, lost neural activation, and filled with fat. Galpin's team now does baseline MRI scans on healthy athletes to catch such issues early. He also notes that penation angle (the orientation of muscle fibers relative to bone) can be altered by fat infiltration, affecting whether a muscle is optimized for force or velocity. This quality metric is becoming central in aging research because it predicts walking speed, balance, and strength in older adults.

Galpin states that his lab has shifted heavily toward morphology (muscle size via MRI) and quality (fat infiltration) because these metrics are stable and reproducible. He acknowledges that morphology doesn't tell you how a muscle functions, but argues that the noise in functional testing often makes it impractical. He cites the example of bench press asymmetry: at 50% of max, trained lifters show no asymmetry in muscle activation, but at 90%, asymmetries 'start flying off the chart.' Similarly, a test done at body weight may miss issues that appear under heavy load or fatigue. Because of this, he sets a lower threshold for action on muscle size asymmetries (5–10%) than on functional ones (10–20%). He also notes that many perceived muscle size asymmetries are actually postural compensations from an injury, not true morphological differences, so imaging is key.

Galpin references a meta-analysis from February of the prior year that examined upper body asymmetries across nearly 90 studies. It provided joint-by-joint charts showing typical asymmetry magnitudes. Shoulder internal/external rotation, adduction/abduction, and flexion/extension commonly show 15–20% side-to-side differences, whereas elbow and wrist asymmetries cluster around 5%. This suggests that what is 'normal' is joint-specific. He also distinguishes between thresholds for injury risk and for peak performance: you might tolerate a higher asymmetry for injury prevention, but to maximize efficiency (e.g., running economy), even smaller asymmetries matter. For example, a 10% asymmetry in ground contact time can increase metabolic cost by 4–8%. He concludes that any asymmetry over 20% is almost certainly problematic regardless of context.

Galpin acknowledges that BFD exists and has research support, but his own published work found it is about twice as common in untrained or weaker individuals compared to age-matched stronger cohorts. In contrast, athletes who train and compete bilaterally (e.g., powerlifters) often show bilateral facilitation—producing more force with two limbs than the sum of their unilateral maxes. Thus, BFD is not a fixed trait; it can be a sign of general weakness or lack of bilateral coordination. For some, it's informative; for others, simply getting stronger eliminates it. This nuance is important when interpreting asymmetry data from unilateral vs bilateral tests.

Galpin notes that while the evidence is not yet overwhelming, there is a signal that early specialization leads to more asymmetries, which in turn are associated with higher injury rates. He ties this to the concept of 'sporting asymmetries'—repeated movement-induced adaptations. If a young athlete performs thousands of asymmetrical movements (e.g., swinging a golf club, throwing, kicking), the body adapts asymmetrically. These adaptations may be beneficial for the sport but can become problematic when they exceed a threshold or when the athlete stops the sport and the asymmetry remains uncorrected. He recommends avoiding specialization before age 14–15, with gymnastics as a possible exception.