To all you men out there, I have a simple question for you……. How sexually fatigued are you? Or to phrase it another way; Think back over the past month, how’s your libido been?

In a previous blog post I talked about Relative Energy Deficiency in Sport (RED-S) syndrome which, in a very overly simplistic explanation, is the extension of the female athlete triad. For those who haven’t heard about the triad, it is a condition that we see in females (typically athletes) where low food intake results in the loss of the female menstrual cycle and reproductive hormones. The loss of these hormones, in particular oestrogen, is highly problematic for the female athlete and her physiology, cardiovascular function and bone health. As a result of low oestrogen levels, there is often reduced bone density and an increased risk of stress fractures.

Research on the female athlete triad is quite extensive but then again, we don’t tend to see a lot of research in ‘female athletes and exercise performance’. Guys, you usually hog this research space. Most of the performance, training and supplement studies have been done in men, with less than 10% of this research being specific to females. Although you men dominate the performance research space, the topic of RED-S and male athlete health is an area that is lacking even though RED-S is recognised to not only occur in females but in men too! So, let’s talk about male athlete health and well-being.

RED-S in men is not too different to the RED-S we see in females; the underlying cause is the same (i.e low energy availability). Or to put it another way, there is an imbalance between energy from food (input) and energy required for exercise and normal physiological functioning (output). The symptoms associated with RED-S are seen in most body systems (gastro, bone, cardiovascular),  which is detrimental to  performance and training effects. We also see impact on an athlete’s mental health. Men’s mental health has historically been a bit of a taboo topic, a bit like females talking about their period/ menstrual cycle. But both topics are regularly occurring natural psychological and physiological processes that occur and, in my opinion, should be topics that should be discussed without any stigma or judgement. So, if you are a guy that is regularly checking in on your mate/s, then I must give you massive kudos.

Physically, male athletes are typically perceived as being incredibly robust, so will often take on large training loads and volumes. It is possible that these large training loads without increased food intake or well managed nutritional/fuel intake can result in large training blocks in low energy availability. Or to get to ‘race weight’ there may be cyclical changes in body weight that may create disordered eating behaviours or unintentional prolonged periods in low energy availability. Male athletes that are most at risk of RED-S are those involved in cycling, rowing, runners, endurance athletes (triathletes), jockeys and weight class combat sports.

Like the female athlete triad, men in a chronic state of low energy availability (whether intentional or not) may present with similar symptoms, now coined the male athlete triad. Yes, there may be a male triad with disorder reproductive function and declines in bone health. Like females, the male reproductive system appears to be sensitive to the stress of exercise and training. In fact, well-trained endurance male athletes could present with 60-80% lower baseline testosterone levels compared to men of a similar age that do not exercise. Research that has taken healthy males and trained them for 6 months has shown a decline in testosterone ranging from 20-40%, but this research was not done with the additional stress of an energy deficit or in a state of low energy availability. In instances where we have both large training loads and inadequate nutritional intake, we may see exaggerated declines in testosterone, known as exercise induced hypogonadal (EIH) syndrome. In EIH, male athletes will present with low testosterone levels, sometimes in the sub clinical ranges (below blood form cut off ranges) and sometimes at the very lower end of the normal. In some cases of EIH, lower pulses of a hormone known as luteinizing hormone, that stimulates testosterone formation in the testes is reported. These research findings would indicate that in EIH in athletic males there is a disruption in the brain-gonad (for men this is the testes) axis like there is in females when they are in an energy deficit and they lose their menstrual cycle.

Now what effect does lower testosterone have on male health. Well testosterone is probably most well-known for its anabolic (muscle building) effects and how it supports muscle growth, maintenance and neuromuscular adaptations. With adequate testosterone levels there will typically be improved size and performance of the skeletal muscles (those muscles that contract during exercise). Testosterone also blunts the hormone hepcidin which lowers the risk of iron deficiency and ensures adequate delivery of iron to the bone marrow for the formation of red blood cells. There are several compelling research studies in males with EIH that have also demonstrated reduced bone mineral density. Let me put it this way, guys if you have a stress fracture or have had more than 2 in your sporting life, then we seriously need to have a talk about your training, nutrition and physiology right now!

There is common belief that males will not show a physical sign when they enter the spectrum of RED-S (females have a key physical sign, being that they lose their menstrual cycle). This suggests that you will not be able to detect RED-S or EIH until the inevitable stress fracture or burnout/overtraining occurs.  But what if I told you there is a simple question and physical sign that you can use to help check in on yourself or your mates or partner? Just like when we check in on mental health, we ask a simple question of how are you going? The simple question you may need to ask is…… over the last month how has your libido been? Or to put it incredibly bluntly (and for a physical symptom) has the frequency of morning erections reduced?

Does this scenario sound familiar…. Guy commits to endurance event and starts training, loves the training and starts to see the fitness gains. Partner is highly supportive. Months go by and race day draws nearer, and people start throwing around jokes of endurance sports being a recipe for ending a romantic relationship. You may hear that guy say he is just tired from training and stressed from work and just not feeling it lately. His partner will probably be telling you about how things are a bit stressed or strained between them. Race day comes, guy races, then follows the post-race recovery period with lots of rest and food. Now ask that partner how they are feeling 1-2 weeks after race day and home life is suddenly great again. Let’s explain this with some physiology, the guy starts training and the consistent training reduces his testosterone levels, albeit quite marginally at first. His training ramps up and nutrition doesn’t change or increase to compensate for the increased exercise demand, and the result is a prolonged period of low energy availability in the lead up to race day. The guy physiologically enters EIH and is tired, stressed, doesn’t feel as recovered from training but puts this down to poor sleep, work life and increase training load. He makes it to race day, does his best and then afterwards he has a break from exercise and as a result the food he is eating is enough to support his normal physiological functioning and the minimal exercise he is doing. Getting the balance right reverses the fatigue, stress and other subjective feelings he was presenting with in the lead up to race day.

Research has suggested that in men with EIH a common subjective response is a reduction in male libido. Large training loads, high workplace stress and lack of sleep, may just be the perfect storm for reduced libido. And yes, I am presenting this quite simply here and I will be the first to recognise that it is not as straight forward as this, but regardless we need to start initiating this conversation before a male athlete reaches the state of burnout or are over-trained. I am aware that this may seem like a very confronting thing to talk about. But if it is something that will benefit your health and performance in the long term, then as an athlete there really should be no stigma attached to this conversation.

So, here are my take home messages;

  • Men can present with RED-S that can affect numerous areas of their physiology that will then affect their health and exercise performance.
  • Key areas affected would be iron regulation, bone health and reproductive function.
  • While men may not have a physical symptom for RED-S they tend to have a very strong subjective response. One that is not only noted by them but may be noted by their partner or significant other.
  • If you are a guy and you are training regularly, especially in the endurance space, then ask yourself this: in the last month have I been sexually fatigued, or have I noticed a change in my libido?

If you cannot associate this change with an increase in work or other life stressors and it has been low for a month or more, then it may be worth having a chat with your coach, physiologist or nutritionist about how you can adjust your training for improved recovery or increase your food intake to help support you during your training.


Dr Claire Badenhorst

Every clinic needs a doctor, at Sports Lab, Claire is ours. Dr Claire Badenhorst  is our physiologist (PhD Exercise Physiology, Academic at Massey University in Auckland) with research focus areas currently in female health, iron deficiency and endurance athletes.