Injury Risk in Strength Training: 5 Myths Put to the Test

Strength training has a reputation problem. In many people’s minds, it’s riskier than running, soccer, or cycling. Squats destroy your knees. Deadlifts ruin your back. Free weights are more dangerous than machines. Heavy training is for lunatics.

The data says otherwise.

The baseline: how safe is strength training really?

Let’s start with the numbers before getting into the individual myths.

Strength training is one of the safest sports there is. The injury rate sits at 0.2–1.0 injuries per 1,000 training hours. For context:

Among college football players, strength-training injuries accounted for only ~1% of total time lost — 99% came from in-game injuries (Kerr et al. 2010).

The most common injuries in strength training: strains and sprains (~46%), mainly in the lower back and shoulder area. Most are mild and heal quickly.

That doesn’t mean injuries are impossible. It means the risk is massively overestimated in public perception.

Myth 1: Deep squats ruin your knees

The most stubborn myth in strength training. It traces back to a single 1959 study — Karl Klein examined 128 weightlifters and concluded that deep squats damage knee ligaments. The problem: the methodology was flawed, and the study was repeatedly refuted over the following decades.

What current research says: A 2024 systematic review evaluated 15 high-quality studies. The result: 14 out of 15 found no negative effect of deep squats on knee health. Several studies even showed that deep squats lead to thicker and stronger cartilage in the knee area.

Deep squats aren’t just safe — with good technique and appropriate loading, they’re protective. → Squat Technique: Individual, Not Dogmatic

Myth 2: Your knees can’t go past your toes

Closely related to Myth 1. In many fitness classes you’ll hear: “Keep your knees behind your toes.” This isn’t just unnecessary — it’s counterproductive.

If you artificially restrict forward knee travel during a squat, the load has to go somewhere else. Straub & Powers (2024) show that the stress shifts to the hips and lower back — with a hip torque increase of over 1,000%.

Your knees travel where they need to go — depending on your limb proportions, stance width, and foot angle. For most people, knees have to go past the toes for the movement to work biomechanically. → Knees Over Toes: The Science

Myth 3: Deadlifts hurt your back

“Deadlifting is the most dangerous exercise in the gym” — a sentence that appears in every other fitness forum. Reality is more nuanced.

What current research says: Trained lifters show natural spinal movement during the deadlift (slight flexion in the lower back) without any elevated injury risk. A 2026 systematic review (Maderas et al., Sports) concludes: the blanket “neutral spine or injury” warning is not supported by the evidence.

That doesn’t mean technique doesn’t matter. What it means:

• Abrupt load jumps are the most consistent risk factor — not the exercise itself.
• Rounding under load during fatigue can be problematic — but slight flexion with clean control is normal and safe.
• Deadlifts activate the spinal erectors more than any other exercise and are deliberately used in physical therapy for rehabilitation.

Dr. Stuart McGill, arguably the most prominent spinal researcher, recommends caution with loaded flexion for people with existing disc problems — his “Big Three” (curl-up, side plank, bird dog) as a foundation. But even McGill’s position refers to pre-existing damage, not healthy backs.

Myth 4: Free weights are more dangerous than machines

Yes — but not for the reason most people assume.

Epidemiological data shows: ~90% of strength-training injuries in emergency rooms came from free-weight training. That sounds alarming. But: 65% of those were accidents — weights that fell on people. It wasn’t the exercise execution that caused injury, but inadequate safety measures (no collars, no spotter, incorrectly set safety pins).

Exercise execution itself shows no systematic difference in injury risk between free weights and machines in controlled studies. What differs: free weights demand more technique and attention. Machines are more forgiving of errors because the movement is guided.

In practice:

• Use a spotter for heavy sets of bench press and squat
• Always use collars
• Set the safety pins in the rack correctly
• If you train alone and are uncertain: use machines for sets close to failure

Myth 5: Heavy training is only for the young

The opposite is true. Older adults in particular benefit enormously from strength training — against sarcopenia (age-related muscle loss), for bone density, fall prevention, and general function. The ACSM 2026 Position Stand explicitly states that strength training is safe and recommended for all age groups.

The adjustments for older trainees are modest: a pain-free range of motion, a more gradual start, more warm-up. But the core principles — progressive overload, compound exercises, sufficient volume — stay the same. → Strength Training After 40

What actually causes injuries

Not the exercise, but the circumstances:

Too-rapid load increases. Adding more than 10% weight at once before technique is solid. This is consistently the strongest risk factor in the research.

Fatigue + form breakdown. Not the exercise itself, but the last few reps with collapsing form. That’s why keeping a buffer of 2–3 reps before failure on compound lifts is worth it.

Muscular imbalances. Too much push, too little pull. Too much quad, not enough hamstring. → Exercise Selection and Balance

Missing warm-up sets. A light warm-up set before each exercise is nearly risk-free and significantly reduces injury risk.

Ego lifting. Weight your technique can’t handle. Everyone knows it, few admit it.

The short version

• Strength training has one of the lowest injury rates of any sport (0.2–1.0 / 1,000 h).
• Deep squats are safe and protect your knees — not the other way around.
• Knees over toes is normal and biomechanically necessary.
• Deadlifts don’t hurt your back with sound technique — they strengthen it.
• Free weights are not inherently more dangerous than machines — but they demand care with safety equipment.
• The real risk factors: too-rapid progression, fatigue, imbalances, missing warm-up sets.

Further reading:

• Squat Technique: Individual, Not Dogmatic
• Knees Over Toes: ATG Science Check
• Training to Failure — How Close Should You Get?
• Exercise Selection and Order
• Warm-Up Protocol for Strength Training

Sources

• Keogh JWL, Winwood PW (2017). The Epidemiology of Injuries Across the Weight-Training Sports. Sports Medicine, 47(3):479–501.
• Kerr ZY, Collins CL, Comstock RD (2010). Epidemiology of Weight Training-Related Injuries. Am J Sports Med. 38(4):765–771.
• Hartmann H, Wirth K, Klusemann M (2013). Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load. Sports Medicine, 43(10):993–1008.
• Maderas B, Pereira G, Machado M (2026). Beyond the Neutral Spine: A Narrative Review and Modern Framework for Low Back Injury Prevention in Deadlifting. Sports, 14(4):151.
• Currier BS, D’Souza AC, Singh MAF et al. (2026). Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. Med Sci Sports Exerc. 58(4):851–872.
• Straub RK, Powers CM (2024). Anterior Knee Displacement during Different Barbell Squat Techniques: A Comprehensive Review. Sports, 11(5):239.