The running injury prevention app

Around 50% of runners experience an injury each year, and the majority of running disorders are overuse injuries (Kakouris et al., 2021). Injury risk is multifactorial: training load, footwear, biomechanics, strength, sleep, and nutrition all play a role.

Two factors stand out in the evidence. First, training load: increasing mileage or intensity faster than the body can structurally adapt is one of the most consistently reported modifiable risk factors. Second, strength training: a meta-analysis by Lauersen et al. (2014) found that strength training reduced overuse injuries by approximately half across sports populations, although evidence specifically in endurance runners is more limited.

myTF focuses on the training load side of the equation, applying peer-reviewed models (including the acute-to-chronic workload ratio, ACR) and our own science-based models (e.g. cumulative overload) to your actual activity data. This gives you a continuous, data-driven view of where your load sits relative to your training history, rather than relying on generic guidelines like "don't increase more than 10% per week". It complements rather than replaces strength work and other prevention strategies.

Shin splints (medial tibial stress syndrome, or MTSS) are one of the most common running injuries, accounting for a substantial share of running and lower-limb overuse injuries (Deshmukh & Phansopkar, 2022).

What are shin splints?

MTSS involves repetitive microtrauma to the muscles and tissues that attach to the inner edge of the shinbone (tibia), particularly the tibialis posterior, soleus, and flexor digitorum longus, along with irritation of the periosteum, the outer layer of bone. This causes exercise-induced pain along the medial tibial border, usually in the middle to lower third of the shin. The pain typically starts as a dull ache during or after running and eases with rest, but if training continues without modification it can become persistent and may progress to a tibial stress fracture.

What causes shin splints in runners?

Rapid increases in training volume are consistently identified as a primary risk factor: the tibial bone and surrounding tissues need time to remodel under load, and increasing mileage faster than these structures can adapt is a common trigger. Other contributing factors include poor or worn footwear, muscular imbalances at the ankle, tight or weak calf muscles, higher body mass index, and running on hard surfaces (Bhusari & Deshmukh, 2023). Female runners and those with a history of previous shin splints are also at elevated risk.

How myTF helps

Because training load spikes are one of the most consistently reported modifiable risk factors, monitoring your acute-to-chronic workload ratio (ACR) is a practical, evidence-informed way to manage your risk alongside other measures such as calf strengthening, sensible footwear, and gradual surface progression. myTF continuously tracks how your weekly mileage compares to your recent training history, so when your load drifts beyond the zones associated with safer progression, you see it before shin pain sets in. This is especially relevant for new runners, runners returning from a break, or anyone ramping up mileage for a race.

Patellofemoral pain ("runner's knee") is the single most prevalent running and cycling overuse injury. A systematic review and meta-analysis by Smith et al. (2018) reported an annual prevalence of 22.7% in the general population, with particularly high rates in amateur runners and adolescent female athletes, making it by far the most common cause of knee pain in active adults.

What is runner's knee?

Patellofemoral pain presents as diffuse pain around or behind the kneecap, typically worsened by running, squatting, using stairs, or prolonged sitting. It is widely accepted to be multifactorial: contributing factors include hip and quadriceps strength, lower-limb biomechanics, foot mechanics, and load-related tissue stress. Among modifiable factors, training errors (sharp week-on-week increases in volume or intensity that outpace tissue adaptation) are commonly implicated, alongside strength deficits at the hip and knee.

How myTF helps

myTF addresses one piece of the puzzle: load progression. It monitors your training across multiple dimensions (distance, longest run, and elevation gain) and flags when your progression exceeds the thresholds that published research associates with elevated injury risk. Because runner's knee tends to develop from cumulative overload rather than a single session, the multi-week view in the planner is particularly useful for spotting gradual drift into higher-risk zones before knee symptoms develop. For best results, combine this with hip and quadriceps strengthening as recommended by current physiotherapy guidance.

Overtraining occurs when cumulative training stress consistently outpaces the body's capacity to recover. The result can be a downward spiral: persistent fatigue, declining performance, disrupted sleep, and an increased risk of injury.

The acute-to-chronic workload ratio (ACR), as described by Blanch & Gabbett (2015), provides one objective way to track this balance. An ACR sustained in the 80–130% range has been associated with lower reported injury risk in several studies; sustained spikes above 150% have been associated with elevated risk.

By calculating your ACR daily and plotting it over time, myTF gives you an early signal that complements how you feel. This is particularly relevant for runners who feel fine during a ramp-up: aerobic fitness adapts in days, but tendons and bone remodel over weeks to months, and overload there often goes unnoticed until damage is already done.

Tendon and ligament injuries (Achilles tendinopathy, patellar tendinopathy, plantar fasciitis, tibial stress fractures) account for a disproportionate share of overuse running injuries and are notoriously slow to heal. Connective tissue has limited blood supply and a slower repair capacity than muscle, which means a tendon injury can sideline a runner for months rather than weeks.

Why they're easy to miss until it's too late

Tendons and ligaments are less richly innervated than muscle, so structural overload often goes unnoticed until damage is accumulating. You can be training hard and feeling good aerobically while your connective tissue is being stressed beyond its current adaptive capacity. By the time pain appears, the structural deficit has often been building for weeks.

How myTF's cumulative overload model helps

myTF's 'Cumulative overload' chart estimates whether your connective tissue has had enough time to structurally adapt to your training. Because it compares the past month of running to the past three months, rather than just the past week, it moves slowly and reflects the gradual drift that can lead to tendon injury before symptoms develop. Many running apps focus on short-term load spikes; myTF's unique cumulative overload model looks at whether your tendons are keeping up with your training over the longer arc of a season.

It is particularly useful in three situations: during a progressive training build towards a goal race, when returning after a break or injury, and after a period of reduced training when fitness has recovered faster than structural readiness. In all three, the aerobic feeling of being “ready” can outpace actual connective tissue adaptation.

Practical guidance

Aim to keep your cumulative overload in the green zone during sustained training blocks. Passing through the orange zone during a deliberate build is normal, but treat persistent time in that zone as a signal to slow the rate of progression. The red zone warrants a planned easy week, not necessarily rest, but enough of a reduction to let adaptation catch up.

For a full explanation of how the metric is calculated and what the zones mean, see What is the 'Cumulative overload risk' chart?

The return-to-running phase carries some of the highest re-injury risk. After time off, your chronic load drops, meaning even a modest run can spike your ACR into the red zone. The evidence supports a graduated, load-monitored return rather than jumping back to pre-injury volume (Taberner et al., 2019).

myTF's planner lets you map out a week-by-week return and instantly see how each session affects your projected ACR. This makes it straightforward to build back progressively while staying within zones associated with lower injury risk in the published literature. We recommend coordinating return-to-running plans with a physiotherapist or qualified clinician where appropriate.

myTF is a training load monitoring and injury risk tool for runners, with support for cycling and swimming. It connects to Strava and applies published sports science models, including the acute-to-chronic workload ratio (ACR), multivariable risk factors, and population-level injury data, to your actual training history.

The goal is to give you an objective, data-informed view of your injury risk that goes beyond generic rules of thumb such as the "10% rule". Thousands of runners use it to manage training load, plan safe mileage progression, and reduce avoidable injury risk. myTF is not a substitute for clinical advice, strength training, or other prevention strategies.