High intensity exercising has continued to grow in popularity in recent years due to its fat-burning, muscle-building effects. But whilst this form of exercise is great for those who don't have a lot of time or space, with such an intense workout comes a lot of stress on the body, and more and more people are injuring themselves during their HIIT training.
If carried out correctly, most people will normally be able to cope with this type of training, but some won't - and often find out once it's too late after the damage has already been done. I see a lot of people in the clinic with knee pain that has developed after high intensity workouts. Pumped up on endorphins from the burn of the exercise, many people only notice a slight twinge at first. However, afterwards they might develop pain, some swelling and stiffness in the joint. The cardinal sign that there could be an actual issue inside a joint is if the joint itself swells up.
The high intensity bit is exactly that: 'high intensity'. Exercises such as squats, lunges, burpees and squat thrusts all put large forces across the knee with the knee in a bent position. Specifically, when you land on one knee with the knee in a bent position, the forces between the back of the kneecap and the front of the knee can be as high as seven times your body-weight, which is massive.
The range of knee injuries caused by HIIT workouts can be varied and also serious. The most common knee injuries that I see in the clinic are tears of the meniscal cartilage shock absorbers in the knee, and damage to the articular cartilage layer that covers the surface of the bones in the joint - particularly affecting the cartilage on the back of the kneecap.
If you have any minor knee symptoms, you should seek medical advice and if knee symptoms fail to settle, or if you're getting significant pain in the knee or any actual swelling in the joint, then this could be a 'red flag'. The best person to see when this occurs is an appropriate knee specialist - specifically a Consultant Orthopaedic Surgeon who specialises in 'soft tissue' knee injuries.
HIIT workouts are effective and a genuinely sensible approach to finding the most intense, time-efficient and effective way to keep fit and strong. But what's good for your muscles, heart and general health isn't necessarily good for your joints, and it becomes a balancing act between the two. The macho approach of 'no pain, no gain' is fine for younger people and people without joint problems; however, if you've got any kind of damage in your knee joint then it can be dangerous. Instead, you should listen carefully to your knees, be gentle with your joints and avoid anything that hurts or aggravates any knee symptoms in any way.