Sports science has confirmed the link between variation in resting heart rate and overtraining. But this link is neither easily understood nor directly correlated. The problem is that an elevated resting heart rate can indicate training stress... but it can also simply mean that you had a rough day at work. To complicate matters, an elevated pulse may be a sign of sympathetic overtraining, whereas a dramatically lowered pulse may indicate parasympathetic stress. Restwise analyzes resting heart rate variability within the context of both your heart rate history and your other daily inputs. Our algorithm then distills this complexity and adjusts the calculation.

Resting heart rate should ideally be monitored during sleep or first thing in the morning, before getting out of bed. Day-to-day variations in resting heart rate of approximately 5% are common and not usually associated with fatigue or stress. However, increases of greater than 5% are typically reported in fatigued or acutely over-reached (sympathetic) individuals.

Sport nutritionists agree that rapid loss of body mass compromises the body's ability to repair itself during intense training. Rapid reduction in body mass occurs as a result of fluid and/or substrate loss, both of which affect recovery and performance. An acute body mass loss of 2% or greater can adversely affect cognitive and physical performance.

Regular monitoring of pre-breakfast body mass can aid in optimizing fluid and energy balance, lead to more efficient recovery and performance. But simply weighing yourself every morning isn't enough. Why? Because hydration, type of food, regularity, etc. can all influence daily weight. Restwise analyzes the body weight input within the context other variables and of your historical trends to interpret daily variability within the larger picture.

As we all know, there is sleep... and then there is sleep. As athletes, we have experienced the after-effects of a hard race or a heavy block of training: a restless night. We have also experienced that magical feeling which comes after several days of high-quality sleep. Fortunately, sleep is one variable that has been studied extensively relative to recovery.

Although there is no consensus on what an "optimal" amount of sleep is, broad agreement exists on the importance of sleep when it comes to repairing the damage that hard training inflicts. Many sleep specialists gravitate around the 8-hour mark. When an athlete regularly sleeps less than this amount, it is possible that recovery will be negatively influenced. Either, or both, sleep volume and quality can be affected, which in turn can undermine recovery strategies.

Although there is little evidence that blood oxygen saturation provides an indication of overtraining or fatigue, the measurement can be a helpful indicator of a variety of non-training-related issues: an athlete's altitude acclimatization process; diagnosing pre-symptomatic bronchitis; highlighting the risk of anemia; detecting the early stages of chronic over-training fatigue, etc.

Normal healthy oxygen saturation values are between 96% and 99% at sea level (values are lower for non-acclimatized athletes at higher altitude). Oxygen saturation below 95% may indicate any of the above referenced issues, of which anemia (usually associated with weakness or fatigue) is the most common among athletes. The proprietary methodology that Restwise uses to incorporate SPO2 into the recovery score utilizes its value as a predictive tool.

Athletes understand that hydration is important, and that an good indicator of hydration is urine color. Pre-training dehydration can compound the effects of prolonged activity on fluid balance, as dehydration of 2% or more can negatively impact cognitive functions and physical performance. It can also affect immune status, body temperature and cardiac output, all of which undermine efforts to recover from training. A urine "pee chart" can provide a useful indication of fasted hydration status, but for athletes who don't want to obsess on their morning pee, Restwise has developed a simple, three-stage color indicator.

Appetite typically decreases with high training load and fatigue, which can result in negative energy balance. Inadequate carbohydrate intake can lead to earlier onset of overreaching symptoms and impaired performance, while insufficient protein and micronutrient intake can impact on immune function, protein synthesis and recovery from training.

Delayed onset muscle soreness (DOMS) is thought to be a result of microscopic tearing of the muscle fibers, resulting in intra-muscular inflammation. DOMS is therefore a normal reaction to high training intensity, which can increase the risk of injury if followed by insufficient rest. Persistent muscle soreness may indicate an increased risk of overuse injury and overtraining syndrome (OTS).

Of course, the phrase "microscopic tearing of the muscle fibers" should alert you to the importance of monitoring this condition relative to recovery. While in some phases of training (initiating a resistance program, for example), you should expect some DOMS, it should not be a chronic condition.

We have all experienced those days when we didn't want to train, bur forced ourselves out the door and had a fantastic experience. We have also had those days when we didn't want to train, so we took a nap and felt much better afterwards. The trick is to be able to distinguish been low motivation derived from over-reaching and low motivation derived from non-physical factors. Subjective level of energy is related to a number of markers of fatigue, including physiological, immunological and psychological markers. Restwise helps you distinguish between days when you are recovered but may feel tired versus days when you may feel tired ... and need to rest.

Profile of Mood States (POMS) was created to evaluate the efficacy of counseling and psychotherapy. It first gained favor among sports psychologists in the late 1970's to help athletes achieve peak performance. While Restwise does not explicitly use one of the POMS tests, we do rely on the extensive body of research that supports it. More recently, researchers have used a medical model - the Central Nervous System score - to quantify non-exercise related stress. Between the two, research confirms the link between mind and body, and the impact that an athlete's mental state has on recovery.

General apathy, mood swings and feelings of depression or anxiety are often indicative of fatigue, illness or over-reaching. These markers are also commonly associated with periods of underperformance.

You may have read that moderate exercise boosts the immune system. Great news! But then you may also have wondered why, during periods of intense training, you often feel that you are "about to get sick." Serious athletes can push their bodies hard enough to become more susceptible to illness, often riding that fine line between wellness and illness.

Headaches, nausea, diarrhea and sore throat are all common symptoms of stress, fatigue and illness. Symptoms of upper respiratory tract infections are common to athletes and, if prolonged, may indicate overtraining. By tracking the presence of these symptoms and considering them in the context of the other signs of fatigue, Restwise helps you stay on the right side of the fine line.

It is no great insight to observe that performance decline is, ultimately, the most valid indicator of fatigue or over-reaching. While brief periods of underperformance may be expected in a carefully constructed training program, prolonged underperformance is a reliable indicator of over-training. Restwise takes a backwards look at your performance to help you ensure that intentional over-reaching does not cross the line into counterproductive overtraining.