A strain is a tear in muscle fibres, usually sudden and felt mid-thigh during sprinting. Tendinopathy is a gradual change in the tendon, most often where the hamstring attaches to the sit bone, and it builds over weeks. They need different loading. Strains progress through lengthened strength work and sprint retraining, while tendinopathy usually starts with isometric holds and avoids deep hip-bend positions early on.

Deep pain under the sit bone when sitting is typical of proximal hamstring tendinopathy. Sitting compresses the tendon against the bone, so pain rises the longer you stay there and eases once you stand. Long drives, hard chairs and cycling often flare it. Softer seating, regular position changes and a graded strength program are usually part of the approach.

Nordic curls are one of the better-studied exercises for hamstring strength, and research in football populations links regular use to lower injury rates. They load the muscle while it lengthens, which is the position most strains occur in. They are demanding, so they are introduced gradually, often starting with assisted or partial-range versions rather than the full movement.

Bruising means small blood vessels have torn, and gravity often carries it down toward the knee or calf over a few days. On its own it does not tell you the grade of injury. What matters more is whether you can bear weight, whether there is a visible gap in the muscle, and how much strength you have lost. Have significant bruising assessed.

Fatigue reduces the muscle’s ability to absorb force and changes your running mechanics, so stride length and control drop off. Studies of match data show a cluster of hamstring injuries in the closing stages of each half. Building sprint conditioning, so late-game running feels closer to early-game running, is a practical part of reducing that risk.

Stretching alone has not been shown to prevent hamstring injuries. Long static stretches before sprinting can briefly reduce force output. A better warm-up combines gradual pace increases, dynamic leg swings and a few build-up runs at close to full speed. Strength work carried out across the week does far more for prevention than anything done in the ten minutes beforehand.