Feeling worn out after a long run or a tough match is completely normal. Your body is doing exactly what it should — working hard and asking for rest. But when fatigue becomes a constant companion that doesn't lift even after days off, or when your performance starts slipping despite putting in the work, something more may be going on.

Excessive fatigue in athletes is more common than most people realise, and it can have many different causes. The good news is that a sports and exercise physician is specifically trained to investigate, diagnose, and treat this kind of problem — helping you get back to doing what you love.

What Does "Excessive Fatigue" Actually Mean?

There's a difference between normal tiredness and the kind of fatigue that starts to affect your daily life and athletic performance. Excessive fatigue in athletes often looks like:

If several of these resonate with you, it's worth seeking a proper assessment rather than simply pushing through or training harder — which can often make things worse.

What Could Be Causing It?

Fatigue rarely has just one cause. In athletes, it's often a combination of factors that build up over time. Some of the most common culprits include:

Overtraining and Under-recovery

When the demands of training outpace your body's ability to recover, fatigue accumulates. This is sometimes called overreaching (short-term) or, in more serious cases, overtraining syndrome. It's not just about doing too much — it's about the balance between load and rest.

Nutritional Deficiencies

Athletes have higher nutritional demands than the general population. Low iron levels (including iron deficiency without anaemia), vitamin D deficiency, and not eating enough overall (which might be part of Relative Energy Deficiency in Sport [RED-S] ) are very common contributors to fatigue and poor performance.

Sleep Disturbance

Poor sleep quality, irregular sleep schedules, or conditions like sleep apnoea can significantly affect how well your body recovers and how energised you feel during the day.

Underlying Medical Conditions

Sometimes fatigue is a sign that something else is going on in the body — such as thyroid problems, anaemia, coeliac disease, or viral illnesses like glandular fever (Epstein-Barr virus). These conditions need to be properly investigated and treated.

Mental Health and Psychological Load

Stress, anxiety, burnout, and low mood all have real, physical effects on energy levels and performance. The mental and emotional side of athletic life — including performance pressure, identity challenges, and life outside sport — plays a bigger role than many people expect.

How Can a Sports and Exercise Physician Help?

A sports and exercise physician is a medical doctor who has completed specialist training in exercise science, sports medicine, and the unique health needs of active people. They are different from a general practitioner, physiotherapist, or personal trainer — though they work closely with all of these health professionals.

When you see a sports and exercise physician for fatigue, here's what you can typically expect:

A Thorough Conversation

Your doctor will want to understand your full picture — your training history and load, your nutrition and sleep habits, your performance concerns, your overall health, and what's been happening in your life more broadly. Nothing is too small to mention.

A Physical Examination

A hands-on examination helps identify any signs of illness, nutritional issues, or other underlying conditions that might be contributing to how you're feeling.

Targeted Testing

Blood tests are often a key part of the workup. Your physician will check for things like iron stores, vitamin D, thyroid function, blood counts, and markers of inflammation. They may also organise other investigations if needed. Importantly, they'll interpret these results in the context of your sport and your body — not just general population reference ranges, which aren't always appropriate for athletes.

A Personalised Management Plan

Once there's a clearer picture of what's driving your fatigue, your sports and exercise physician will work with you to create a plan. This might include adjustments to your training load, nutritional support (sometimes alongside a sports dietitian), targeted supplementation or medical treatment, and referral to other specialists if needed — such as a psychologist, sleep physician, or endocrinologist.

Importantly, the goal isn't just to feel less tired — it's to help you perform at your best sustainably, without compromising your long-term health.

When Should You See Someone?

You don't need to wait until you're completely burnt out before seeking help. In fact, the earlier excessive fatigue is addressed, the faster the recovery tends to be. Consider booking an appointment if:

You Deserve to Feel Your Best

Athletes often feel pressure to push through fatigue — to toughen up, train harder, or simply cope. But your body sends these signals for a reason. Excessive fatigue is not a character flaw or a sign of weakness. It's information, and it deserves to be taken seriously.

With the right support, most athletes are able to identify the cause of their fatigue, address it effectively, and return to training and competition feeling strong, energised, and motivated.

A sports and exercise physician is your partner in that process — bringing medical expertise, a genuine understanding of athletic life, and a commitment to helping you thrive in your sport for the long term.