The load borne by the Achilles tendon during exercise: A systematic review of normative values.

Researchers searched three major medical databases for studies that measured how much force the Achilles tendon experiences during everyday activities and exercise. They found only 11 studies that met their criteria, most of which looked at walking and running rather than rehabilitation exercises. The tendon load ranged from about 2.7 to 4 times body weight when walking, jumped to 4 to nearly 8 times body weight when running, and varied wildly from less than half to over 7 times body weight depending on which strengthening exercise was being done.

The researchers were able to sketch out a rough framework showing how exercises might be ordered from lighter to heavier loading, and they drew some preliminary connections to everyday movement speeds. However, they found inconsistencies in how tendon load changed with walking or running speed, which suggests the picture is more complicated than it first appears.

Scientists looked at how much stress and strain the Achilles tendon goes through during normal daily activities like walking and running, as well as during exercises that specifically target this tendon. This matters because understanding these forces helps therapists design safer rehabilitation programs for people recovering from Achilles tendon problems.

The research found that walking puts a relatively moderate load on the tendon, running puts considerably more stress on it, and different strengthening exercises create very different levels of demand. What the researchers discovered was somewhat patchy and incomplete.

There is clearly not yet a complete map of which exercises load the tendon lightly, moderately, or heavily, and some of the patterns they found didn't always make perfect sense. More research in both healthy people and those with tendon injuries would fill in important gaps.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This systematic review surveyed the mechanical load literature on the Achilles tendon and found the evidence base to be surprisingly sparse. Only 11 studies met inclusion criteria, and the vast majority focused on walking and running rather than rehabilitation-specific movements.

The tendon loading values themselves ranged considerably even within the same activity type, suggesting variability from measurement method, participant characteristics, or both. The authors extracted enough data to propose a loose exercise progression framework, which may have some practical value for staging interventions, but they candidly noted inconsistencies in the relationship between movement speed and tendon loading that warrant caution.

The gap between what we know about locomotor loading and what we know about rehabilitation exercise loading is particularly notable and represents a genuine knowledge deficit in clinical practice. The authors appropriately concluded that further research is needed both to resolve these inconsistencies and to expand the dataset in both asymptomatic and injured populations.