Achilles tendon pain is a common obstacle for many runners, often developing into a persistent issue that questions the ability to maintain a training schedule. This discomfort signifies Achilles tendinopathy, a condition resulting from the tendon’s inability to adapt to physical demands. The challenge is balancing rest, which causes the tendon to lose capacity, and continued activity, which risks further irritation. Returning to running requires a strategic approach focused on rebuilding strength rather than masking symptoms.
The Immediate Decision: Should You Run Today?
The decision to run with Achilles tendon discomfort is managed by closely monitoring pain levels using a Pain Monitoring Model. This model guides activity based on the tendon’s reaction. Running is generally permissible if the pain remains tolerable, typically rated below a five out of ten on a numerical pain scale during the activity itself.
The tendon’s response in the 24 hours following the run is the most informative metric. If pain or morning stiffness has not increased the day after your run, the load was appropriate, and you can attempt the same activity level again. Conversely, if pain spikes the next morning, it indicates the tendon was overloaded, and running volume or intensity must be reduced. This model allows for continued, pain-guided loading, which is beneficial for long-term tendon health.
Understanding Achilles Tendinopathy
The term Achilles tendinitis refers to an acute injury characterized primarily by inflammation, often seen following a sudden overload. However, the chronic pain experienced by many runners is more accurately described as Achilles tendinopathy or tendinosis. This long-term condition involves structural changes within the tendon, including the disorganization and degeneration of collagen fibers.
This degenerative process is caused by repeated microtrauma and a failed healing response. The tendon tissue develops a haphazard structure and may exhibit neovascularization (the growth of new blood vessels and nerves). Recognizing the issue is primarily degenerative shifts the focus from simple rest and anti-inflammatory drugs to stimulating tendon repair through controlled loading. Common symptoms include localized pain, thickening of the tendon, and marked stiffness, especially first thing in the morning.
Acute Management and Pain Reduction
When the tendon is highly sensitive, the immediate goal is to reduce irritation without resorting to complete rest, which weakens the tendon. Relative rest, or activity modification, is advised, meaning you temporarily stop activities that aggravate the pain most, such as high-intensity sprints or jumping. Wearing a heel lift provides immediate relief by slightly shortening the calf muscle-tendon unit. This elevation decreases tensile strain and reduces compression of the tendon against the heel bone, which is especially helpful for insertional tendinopathy.
These heel lifts must be used bilaterally, in both shoes, to prevent creating a functional leg length discrepancy. Since chronic tendinopathy lacks significant inflammation, ice and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) offer limited therapeutic benefit beyond temporary pain relief. Choosing supportive footwear and avoiding walking barefoot, which causes maximum tendon stretch, are effective ways to manage load throughout the day.
Structured Rehabilitation and Safe Return to Running
The long-term resolution for Achilles tendinopathy relies on a progressive loading program designed to stimulate collagen fibers to remodel into a stronger, more functional structure. Exercise therapy is the treatment modality with the highest level of evidence, and it must be consistent and challenging to be effective. The initial focus often involves eccentric exercises, such as the Alfredson protocol, which strengthens the tendon as the muscle lengthens under load.
The Alfredson protocol involves standing on a step, pushing up with both feet, and slowly lowering the heel with only the injured leg. This is typically performed in three sets of fifteen repetitions, twice daily. As pain allows, these heel drops are progressed by adding external load, such as holding weights.
A newer, equally effective approach is Heavy Slow Resistance (HSR) training. HSR uses high weight loads with a slow tempo for both the lifting (concentric) and lowering (eccentric) phases of the movement. HSR often involves three sessions per week and gradually increases the load while decreasing the repetitions, moving from about fifteen-rep maximum down to six-rep maximum over twelve weeks.
Once a baseline of strength is established and pain is well-controlled, the return to running must be gradual to prevent relapse. The ten percent rule suggests not increasing weekly running volume by more than ten percent, providing a safe framework for progression. This conservative increase allows the tendon’s structure time to adapt to the increasing demands of running, which subjects the Achilles to forces six to eight times body weight. Incorporating cross-training, such as cycling or swimming, helps maintain cardiovascular fitness without excessively overloading the recovering tendon.