The niggle index

Knee pain in wall balls, shin splints, sore shoulders overhead, a back that folds mid-race: what commonly causes each, which movements provoke it, what you can keep training, and the signs that mean get it assessed. General information, not medical advice.

Read this first: This is general training information, not medical advice, and nothing here is a diagnosis. The same pain can have very different causes, and only a qualified professional who can assess you in person can tell which one is yours. If pain is severe, getting worse, or not settling, get it looked at.

Knee

The joint that pays for every wall ball, lunge and kilometre, and the one most often blamed for a hip's shortcomings.

Knee pain in wall balls and squats: A dull ache around or just behind the kneecap that shows up in repeated squatting (wall balls, air squats, lunges) and often lingers on stairs and after sitting. It is the single most common complaint in high-rep functional training.
Pain just below the kneecap: A sharp, pinpoint pain on the tendon between the kneecap and the shin bone, provoked by jumping and deep loaded squatting. Unlike a diffuse kneecap ache, you can usually put one finger on the exact spot.

Lower leg, ankle & foot

Shins, calves, Achilles and heel, where a gym athlete's new running volume lands first.

Shin splints: An ache along the inside edge of the shin bone that builds through a run and eases with rest. It is the classic complaint of anyone adding running volume to a training week that was previously all gym.
Achilles pain and stiffness: Stiffness and pain in the tendon above the heel, worst in the first steps of the morning and after sitting. It builds slowly over weeks and responds to loading, not to rest alone.
Calf strain and cramping: A sudden grab or tear in the back of the lower leg, usually mid-run or on an acceleration. Distinct from a slow-building ache: you almost always know the exact moment it happened.
Heel and arch pain: Sharp pain under the heel or along the arch, at its worst in the first steps of the morning. It is stubborn, it responds slowly, and it rarely needs anything dramatic to settle.

Hip, groin & hamstring

Sleds, lunges and speed work all converge here, and it is the region most often mistaken for tightness.

Hip flexor pain and tightness: A pulling ache at the front of the hip that shows up in the sled push, lunges and knee drive. It usually reflects a hip flexor doing more work than it has been trained for, not a tight muscle that needs stretching.
Pinching in the front of the hip when squatting: A sharp pinch deep in the front of the hip as you approach the bottom of a squat. It is a blocking sensation rather than a muscular one, and it usually shows the squat needs adjusting to the hip you have.
Groin and adductor pain: Pain along the inner thigh or where it meets the pelvis, provoked by lateral movement, wide stances and the sled pull. Often builds gradually, occasionally arrives all at once.
Hamstring pain and strain: Either a sudden grab in the back of the thigh at speed, or a slow-building ache right under the sit bone that hurts most when sitting. The two behave very differently and need to be told apart.

Lower back

The two backs of hybrid training: the one that hurts after heavy pulling, and the one that folds in the second half of a race.

Lower back pain after deadlifts: A stiff, sore lower back in the day or two after heavy pulling. Extremely common, usually far less serious than it feels, and rarely a reason to stop lifting entirely.
Lower back pain during a race: A back that locks up mid-race, usually somewhere between the farmers carry and the sandbag lunges, and turns the last stations into damage limitation. This is nearly always an endurance problem, not a strength one.

Shoulder

Overhead volume, kipping volume and pressing that outgrew its pulling: the three ways shoulders get sore.

Shoulder pain going overhead: A pinching ache on the outside or front of the shoulder in a specific overhead range: wall balls, ski erg, thrusters. Typically a load-tolerance problem in the cuff rather than damage to the joint.
Front-of-shoulder pain in pull-ups and dips: A localised ache at the front of the shoulder, where the biceps tendon runs, provoked by hanging, kipping and dipping. Common in anyone building gymnastics volume quickly.

Elbow & wrist

Grip and rack positions accumulate load across every session of the week and get trained directly in almost none of them.

Elbow pain from grip work: Pain on the inside or outside of the elbow that shows up after grip-heavy blocks: farmers carries, sled pulls, pull-ups. It builds quietly for weeks and then makes carrying a shopping bag hurt.
Wrist pain in the front rack: Pain at the back of the wrist when the bar sits in the front rack: front squats, cleans, thrusters. Usually a combination of range, position and a wrist that has never been loaded in that shape.

Sweatlas is not a medical provider. Everything in the niggle index is general information about training, written for healthy adults, and it is not medical advice, diagnosis or treatment. Do not use it to self-diagnose or to delay getting care. If you have pain that is severe, worsening, or not settling, or you have any of the warning signs listed on the page, see a doctor or a qualified physiotherapist.